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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * n_gsm.c GSM 0710 tty multiplexor
4 * Copyright (c) 2009/10 Intel Corporation
5 * Copyright (c) 2022/23 Siemens Mobility GmbH
6 *
7 * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
8 *
9 * Outgoing path:
10 * tty -> DLCI fifo -> scheduler -> GSM MUX data queue ---o-> ldisc
11 * control message -> GSM MUX control queue --ยด
12 *
13 * Incoming path:
14 * ldisc -> gsm_queue() -o--> tty
15 * `-> gsm_control_response()
16 *
17 * TO DO:
18 * Mostly done: ioctls for setting modes/timing
19 * Partly done: hooks so you can pull off frames to non tty devs
20 * Restart DLCI 0 when it closes ?
21 * Improve the tx engine
22 * Resolve tx side locking by adding a queue_head and routing
23 * all control traffic via it
24 * General tidy/document
25 * Review the locking/move to refcounts more (mux now moved to an
26 * alloc/free model ready)
27 * Use newest tty open/close port helpers and install hooks
28 * What to do about power functions ?
29 * Termios setting and negotiation
30 * Do we need a 'which mux are you' ioctl to correlate mux and tty sets
31 *
32 */
33
34#include <linux/types.h>
35#include <linux/major.h>
36#include <linux/errno.h>
37#include <linux/signal.h>
38#include <linux/fcntl.h>
39#include <linux/sched/signal.h>
40#include <linux/interrupt.h>
41#include <linux/tty.h>
42#include <linux/bitfield.h>
43#include <linux/ctype.h>
44#include <linux/mm.h>
45#include <linux/math.h>
46#include <linux/nospec.h>
47#include <linux/string.h>
48#include <linux/slab.h>
49#include <linux/poll.h>
50#include <linux/bitops.h>
51#include <linux/file.h>
52#include <linux/uaccess.h>
53#include <linux/module.h>
54#include <linux/timer.h>
55#include <linux/tty_flip.h>
56#include <linux/tty_driver.h>
57#include <linux/serial.h>
58#include <linux/kfifo.h>
59#include <linux/skbuff.h>
60#include <net/arp.h>
61#include <linux/ip.h>
62#include <linux/netdevice.h>
63#include <linux/etherdevice.h>
64#include <linux/gsmmux.h>
65#include "tty.h"
66
67static int debug;
68module_param(debug, int, 0600);
69
70/* Module debug bits */
71#define DBG_DUMP BIT(0) /* Data transmission dump. */
72#define DBG_CD_ON BIT(1) /* Always assume CD line on. */
73#define DBG_DATA BIT(2) /* Data transmission details. */
74#define DBG_ERRORS BIT(3) /* Details for fail conditions. */
75#define DBG_TTY BIT(4) /* Transmission statistics for DLCI TTYs. */
76#define DBG_PAYLOAD BIT(5) /* Limits DBG_DUMP to payload frames. */
77
78/* Defaults: these are from the specification */
79
80#define T1 10 /* 100mS */
81#define T2 34 /* 333mS */
82#define T3 10 /* 10s */
83#define N2 3 /* Retry 3 times */
84#define K 2 /* outstanding I frames */
85
86#define MAX_T3 255 /* In seconds. */
87#define MAX_WINDOW_SIZE 7 /* Limit of K in error recovery mode. */
88
89/* Use long timers for testing at low speed with debug on */
90#ifdef DEBUG_TIMING
91#define T1 100
92#define T2 200
93#endif
94
95/*
96 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
97 * limits so this is plenty
98 */
99#define MAX_MRU 1500
100#define MAX_MTU 1500
101#define MIN_MTU (PROT_OVERHEAD + 1)
102/* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */
103#define PROT_OVERHEAD 7
104#define GSM_NET_TX_TIMEOUT (HZ*10)
105
106/*
107 * struct gsm_mux_net - network interface
108 *
109 * Created when net interface is initialized.
110 */
111struct gsm_mux_net {
112 struct kref ref;
113 struct gsm_dlci *dlci;
114};
115
116/*
117 * Each block of data we have queued to go out is in the form of
118 * a gsm_msg which holds everything we need in a link layer independent
119 * format
120 */
121
122struct gsm_msg {
123 struct list_head list;
124 u8 addr; /* DLCI address + flags */
125 u8 ctrl; /* Control byte + flags */
126 unsigned int len; /* Length of data block (can be zero) */
127 u8 *data; /* Points into buffer but not at the start */
128 u8 buffer[];
129};
130
131enum gsm_dlci_state {
132 DLCI_CLOSED,
133 DLCI_WAITING_CONFIG, /* Waiting for DLCI configuration from user */
134 DLCI_CONFIGURE, /* Sending PN (for adaption > 1) */
135 DLCI_OPENING, /* Sending SABM not seen UA */
136 DLCI_OPEN, /* SABM/UA complete */
137 DLCI_CLOSING, /* Sending DISC not seen UA/DM */
138};
139
140enum gsm_dlci_mode {
141 DLCI_MODE_ABM, /* Normal Asynchronous Balanced Mode */
142 DLCI_MODE_ADM, /* Asynchronous Disconnected Mode */
143};
144
145/*
146 * Each active data link has a gsm_dlci structure associated which ties
147 * the link layer to an optional tty (if the tty side is open). To avoid
148 * complexity right now these are only ever freed up when the mux is
149 * shut down.
150 *
151 * At the moment we don't free DLCI objects until the mux is torn down
152 * this avoid object life time issues but might be worth review later.
153 */
154
155struct gsm_dlci {
156 struct gsm_mux *gsm;
157 int addr;
158 enum gsm_dlci_state state;
159 struct mutex mutex;
160
161 /* Link layer */
162 enum gsm_dlci_mode mode;
163 spinlock_t lock; /* Protects the internal state */
164 struct timer_list t1; /* Retransmit timer for SABM and UA */
165 int retries;
166 /* Uplink tty if active */
167 struct tty_port port; /* The tty bound to this DLCI if there is one */
168#define TX_SIZE 4096 /* Must be power of 2. */
169 struct kfifo fifo; /* Queue fifo for the DLCI */
170 int adaption; /* Adaption layer in use */
171 int prev_adaption;
172 u32 modem_rx; /* Our incoming virtual modem lines */
173 u32 modem_tx; /* Our outgoing modem lines */
174 unsigned int mtu;
175 bool dead; /* Refuse re-open */
176 /* Configuration */
177 u8 prio; /* Priority */
178 u8 ftype; /* Frame type */
179 u8 k; /* Window size */
180 /* Flow control */
181 bool throttled; /* Private copy of throttle state */
182 bool constipated; /* Throttle status for outgoing */
183 /* Packetised I/O */
184 struct sk_buff *skb; /* Frame being sent */
185 struct sk_buff_head skb_list; /* Queued frames */
186 /* Data handling callback */
187 void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
188 void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
189 struct net_device *net; /* network interface, if created */
190};
191
192/*
193 * Parameter bits used for parameter negotiation according to 3GPP 27.010
194 * chapter 5.4.6.3.1.
195 */
196
197struct gsm_dlci_param_bits {
198 u8 d_bits;
199 u8 i_cl_bits;
200 u8 p_bits;
201 u8 t_bits;
202 __le16 n_bits;
203 u8 na_bits;
204 u8 k_bits;
205};
206
207static_assert(sizeof(struct gsm_dlci_param_bits) == 8);
208
209#define PN_D_FIELD_DLCI GENMASK(5, 0)
210#define PN_I_CL_FIELD_FTYPE GENMASK(3, 0)
211#define PN_I_CL_FIELD_ADAPTION GENMASK(7, 4)
212#define PN_P_FIELD_PRIO GENMASK(5, 0)
213#define PN_T_FIELD_T1 GENMASK(7, 0)
214#define PN_N_FIELD_N1 GENMASK(15, 0)
215#define PN_NA_FIELD_N2 GENMASK(7, 0)
216#define PN_K_FIELD_K GENMASK(2, 0)
217
218/* Total number of supported devices */
219#define GSM_TTY_MINORS 256
220
221/* DLCI 0, 62/63 are special or reserved see gsmtty_open */
222
223#define NUM_DLCI 64
224
225/*
226 * DLCI 0 is used to pass control blocks out of band of the data
227 * flow (and with a higher link priority). One command can be outstanding
228 * at a time and we use this structure to manage them. They are created
229 * and destroyed by the user context, and updated by the receive paths
230 * and timers
231 */
232
233struct gsm_control {
234 u8 cmd; /* Command we are issuing */
235 u8 *data; /* Data for the command in case we retransmit */
236 int len; /* Length of block for retransmission */
237 int done; /* Done flag */
238 int error; /* Error if any */
239};
240
241enum gsm_encoding {
242 GSM_BASIC_OPT,
243 GSM_ADV_OPT,
244};
245
246enum gsm_mux_state {
247 GSM_SEARCH,
248 GSM0_ADDRESS,
249 GSM0_CONTROL,
250 GSM0_LEN0,
251 GSM0_LEN1,
252 GSM0_DATA,
253 GSM0_FCS,
254 GSM0_SSOF,
255 GSM1_START,
256 GSM1_ADDRESS,
257 GSM1_CONTROL,
258 GSM1_DATA,
259 GSM1_OVERRUN,
260};
261
262/*
263 * Each GSM mux we have is represented by this structure. If we are
264 * operating as an ldisc then we use this structure as our ldisc
265 * state. We need to sort out lifetimes and locking with respect
266 * to the gsm mux array. For now we don't free DLCI objects that
267 * have been instantiated until the mux itself is terminated.
268 *
269 * To consider further: tty open versus mux shutdown.
270 */
271
272struct gsm_mux {
273 struct tty_struct *tty; /* The tty our ldisc is bound to */
274 spinlock_t lock;
275 struct mutex mutex;
276 unsigned int num;
277 struct kref ref;
278
279 /* Events on the GSM channel */
280 wait_queue_head_t event;
281
282 /* ldisc send work */
283 struct work_struct tx_work;
284
285 /* Bits for GSM mode decoding */
286
287 /* Framing Layer */
288 u8 *buf;
289 enum gsm_mux_state state;
290 unsigned int len;
291 unsigned int address;
292 unsigned int count;
293 bool escape;
294 enum gsm_encoding encoding;
295 u8 control;
296 u8 fcs;
297 u8 *txframe; /* TX framing buffer */
298
299 /* Method for the receiver side */
300 void (*receive)(struct gsm_mux *gsm, u8 ch);
301
302 /* Link Layer */
303 unsigned int mru;
304 unsigned int mtu;
305 int initiator; /* Did we initiate connection */
306 bool dead; /* Has the mux been shut down */
307 struct gsm_dlci *dlci[NUM_DLCI];
308 int old_c_iflag; /* termios c_iflag value before attach */
309 bool constipated; /* Asked by remote to shut up */
310 bool has_devices; /* Devices were registered */
311
312 spinlock_t tx_lock;
313 unsigned int tx_bytes; /* TX data outstanding */
314#define TX_THRESH_HI 8192
315#define TX_THRESH_LO 2048
316 struct list_head tx_ctrl_list; /* Pending control packets */
317 struct list_head tx_data_list; /* Pending data packets */
318
319 /* Control messages */
320 struct timer_list kick_timer; /* Kick TX queuing on timeout */
321 struct timer_list t2_timer; /* Retransmit timer for commands */
322 int cretries; /* Command retry counter */
323 struct gsm_control *pending_cmd;/* Our current pending command */
324 spinlock_t control_lock; /* Protects the pending command */
325
326 /* Keep-alive */
327 struct timer_list ka_timer; /* Keep-alive response timer */
328 u8 ka_num; /* Keep-alive match pattern */
329 signed int ka_retries; /* Keep-alive retry counter, -1 if not yet initialized */
330
331 /* Configuration */
332 int adaption; /* 1 or 2 supported */
333 u8 ftype; /* UI or UIH */
334 int t1, t2; /* Timers in 1/100th of a sec */
335 unsigned int t3; /* Power wake-up timer in seconds. */
336 int n2; /* Retry count */
337 u8 k; /* Window size */
338 bool wait_config; /* Wait for configuration by ioctl before DLCI open */
339 u32 keep_alive; /* Control channel keep-alive in 10ms */
340
341 /* Statistics (not currently exposed) */
342 unsigned long bad_fcs;
343 unsigned long malformed;
344 unsigned long io_error;
345 unsigned long open_error;
346 unsigned long bad_size;
347 unsigned long unsupported;
348};
349
350
351/*
352 * Mux objects - needed so that we can translate a tty index into the
353 * relevant mux and DLCI.
354 */
355
356#define MAX_MUX 4 /* 256 minors */
357static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */
358static DEFINE_SPINLOCK(gsm_mux_lock);
359
360static struct tty_driver *gsm_tty_driver;
361
362/*
363 * This section of the driver logic implements the GSM encodings
364 * both the basic and the 'advanced'. Reliable transport is not
365 * supported.
366 */
367
368#define CR 0x02
369#define EA 0x01
370#define PF 0x10
371
372/* I is special: the rest are ..*/
373#define RR 0x01
374#define UI 0x03
375#define RNR 0x05
376#define REJ 0x09
377#define DM 0x0F
378#define SABM 0x2F
379#define DISC 0x43
380#define UA 0x63
381#define UIH 0xEF
382
383/* Channel commands */
384#define CMD_NSC 0x09
385#define CMD_TEST 0x11
386#define CMD_PSC 0x21
387#define CMD_RLS 0x29
388#define CMD_FCOFF 0x31
389#define CMD_PN 0x41
390#define CMD_RPN 0x49
391#define CMD_FCON 0x51
392#define CMD_CLD 0x61
393#define CMD_SNC 0x69
394#define CMD_MSC 0x71
395
396/* Virtual modem bits */
397#define MDM_FC 0x01
398#define MDM_RTC 0x02
399#define MDM_RTR 0x04
400#define MDM_IC 0x20
401#define MDM_DV 0x40
402
403#define GSM0_SOF 0xF9
404#define GSM1_SOF 0x7E
405#define GSM1_ESCAPE 0x7D
406#define GSM1_ESCAPE_BITS 0x20
407#define XON 0x11
408#define XOFF 0x13
409#define ISO_IEC_646_MASK 0x7F
410
411static const struct tty_port_operations gsm_port_ops;
412
413/*
414 * CRC table for GSM 0710
415 */
416
417static const u8 gsm_fcs8[256] = {
418 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
419 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
420 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
421 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
422 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
423 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
424 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
425 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
426 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
427 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
428 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
429 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
430 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
431 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
432 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
433 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
434 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
435 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
436 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
437 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
438 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
439 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
440 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
441 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
442 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
443 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
444 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
445 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
446 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
447 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
448 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
449 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
450};
451
452#define INIT_FCS 0xFF
453#define GOOD_FCS 0xCF
454
455static void gsm_dlci_close(struct gsm_dlci *dlci);
456static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
457static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
458static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
459 u8 ctrl);
460static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg);
461static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr);
462static void gsmld_write_trigger(struct gsm_mux *gsm);
463static void gsmld_write_task(struct work_struct *work);
464
465/**
466 * gsm_fcs_add - update FCS
467 * @fcs: Current FCS
468 * @c: Next data
469 *
470 * Update the FCS to include c. Uses the algorithm in the specification
471 * notes.
472 */
473
474static inline u8 gsm_fcs_add(u8 fcs, u8 c)
475{
476 return gsm_fcs8[fcs ^ c];
477}
478
479/**
480 * gsm_fcs_add_block - update FCS for a block
481 * @fcs: Current FCS
482 * @c: buffer of data
483 * @len: length of buffer
484 *
485 * Update the FCS to include c. Uses the algorithm in the specification
486 * notes.
487 */
488
489static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
490{
491 while (len--)
492 fcs = gsm_fcs8[fcs ^ *c++];
493 return fcs;
494}
495
496/**
497 * gsm_read_ea - read a byte into an EA
498 * @val: variable holding value
499 * @c: byte going into the EA
500 *
501 * Processes one byte of an EA. Updates the passed variable
502 * and returns 1 if the EA is now completely read
503 */
504
505static int gsm_read_ea(unsigned int *val, u8 c)
506{
507 /* Add the next 7 bits into the value */
508 *val <<= 7;
509 *val |= c >> 1;
510 /* Was this the last byte of the EA 1 = yes*/
511 return c & EA;
512}
513
514/**
515 * gsm_read_ea_val - read a value until EA
516 * @val: variable holding value
517 * @data: buffer of data
518 * @dlen: length of data
519 *
520 * Processes an EA value. Updates the passed variable and
521 * returns the processed data length.
522 */
523static unsigned int gsm_read_ea_val(unsigned int *val, const u8 *data, int dlen)
524{
525 unsigned int len = 0;
526
527 for (; dlen > 0; dlen--) {
528 len++;
529 if (gsm_read_ea(val, *data++))
530 break;
531 }
532 return len;
533}
534
535/**
536 * gsm_encode_modem - encode modem data bits
537 * @dlci: DLCI to encode from
538 *
539 * Returns the correct GSM encoded modem status bits (6 bit field) for
540 * the current status of the DLCI and attached tty object
541 */
542
543static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
544{
545 u8 modembits = 0;
546 /* FC is true flow control not modem bits */
547 if (dlci->throttled)
548 modembits |= MDM_FC;
549 if (dlci->modem_tx & TIOCM_DTR)
550 modembits |= MDM_RTC;
551 if (dlci->modem_tx & TIOCM_RTS)
552 modembits |= MDM_RTR;
553 if (dlci->modem_tx & TIOCM_RI)
554 modembits |= MDM_IC;
555 if (dlci->modem_tx & TIOCM_CD || dlci->gsm->initiator)
556 modembits |= MDM_DV;
557 /* special mappings for passive side to operate as UE */
558 if (dlci->modem_tx & TIOCM_OUT1)
559 modembits |= MDM_IC;
560 if (dlci->modem_tx & TIOCM_OUT2)
561 modembits |= MDM_DV;
562 return modembits;
563}
564
565static void gsm_hex_dump_bytes(const char *fname, const u8 *data,
566 unsigned long len)
567{
568 char *prefix;
569
570 if (!fname) {
571 print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, data, len,
572 true);
573 return;
574 }
575
576 prefix = kasprintf(GFP_ATOMIC, "%s: ", fname);
577 if (!prefix)
578 return;
579 print_hex_dump(KERN_INFO, prefix, DUMP_PREFIX_OFFSET, 16, 1, data, len,
580 true);
581 kfree(prefix);
582}
583
584/**
585 * gsm_encode_params - encode DLCI parameters
586 * @dlci: DLCI to encode from
587 * @params: buffer to fill with the encoded parameters
588 *
589 * Encodes the parameters according to GSM 07.10 section 5.4.6.3.1
590 * table 3.
591 */
592static int gsm_encode_params(const struct gsm_dlci *dlci,
593 struct gsm_dlci_param_bits *params)
594{
595 const struct gsm_mux *gsm = dlci->gsm;
596 unsigned int i, cl;
597
598 switch (dlci->ftype) {
599 case UIH:
600 i = 0; /* UIH */
601 break;
602 case UI:
603 i = 1; /* UI */
604 break;
605 default:
606 pr_debug("unsupported frame type %d\n", dlci->ftype);
607 return -EINVAL;
608 }
609
610 switch (dlci->adaption) {
611 case 1: /* Unstructured */
612 cl = 0; /* convergence layer type 1 */
613 break;
614 case 2: /* Unstructured with modem bits. */
615 cl = 1; /* convergence layer type 2 */
616 break;
617 default:
618 pr_debug("unsupported adaption %d\n", dlci->adaption);
619 return -EINVAL;
620 }
621
622 params->d_bits = FIELD_PREP(PN_D_FIELD_DLCI, dlci->addr);
623 /* UIH, convergence layer type 1 */
624 params->i_cl_bits = FIELD_PREP(PN_I_CL_FIELD_FTYPE, i) |
625 FIELD_PREP(PN_I_CL_FIELD_ADAPTION, cl);
626 params->p_bits = FIELD_PREP(PN_P_FIELD_PRIO, dlci->prio);
627 params->t_bits = FIELD_PREP(PN_T_FIELD_T1, gsm->t1);
628 params->n_bits = cpu_to_le16(FIELD_PREP(PN_N_FIELD_N1, dlci->mtu));
629 params->na_bits = FIELD_PREP(PN_NA_FIELD_N2, gsm->n2);
630 params->k_bits = FIELD_PREP(PN_K_FIELD_K, dlci->k);
631
632 return 0;
633}
634
635/**
636 * gsm_register_devices - register all tty devices for a given mux index
637 *
638 * @driver: the tty driver that describes the tty devices
639 * @index: the mux number is used to calculate the minor numbers of the
640 * ttys for this mux and may differ from the position in the
641 * mux array.
642 */
643static int gsm_register_devices(struct tty_driver *driver, unsigned int index)
644{
645 struct device *dev;
646 int i;
647 unsigned int base;
648
649 if (!driver || index >= MAX_MUX)
650 return -EINVAL;
651
652 base = index * NUM_DLCI; /* first minor for this index */
653 for (i = 1; i < NUM_DLCI; i++) {
654 /* Don't register device 0 - this is the control channel
655 * and not a usable tty interface
656 */
657 dev = tty_register_device(gsm_tty_driver, base + i, NULL);
658 if (IS_ERR(dev)) {
659 if (debug & DBG_ERRORS)
660 pr_info("%s failed to register device minor %u",
661 __func__, base + i);
662 for (i--; i >= 1; i--)
663 tty_unregister_device(gsm_tty_driver, base + i);
664 return PTR_ERR(dev);
665 }
666 }
667
668 return 0;
669}
670
671/**
672 * gsm_unregister_devices - unregister all tty devices for a given mux index
673 *
674 * @driver: the tty driver that describes the tty devices
675 * @index: the mux number is used to calculate the minor numbers of the
676 * ttys for this mux and may differ from the position in the
677 * mux array.
678 */
679static void gsm_unregister_devices(struct tty_driver *driver,
680 unsigned int index)
681{
682 int i;
683 unsigned int base;
684
685 if (!driver || index >= MAX_MUX)
686 return;
687
688 base = index * NUM_DLCI; /* first minor for this index */
689 for (i = 1; i < NUM_DLCI; i++) {
690 /* Don't unregister device 0 - this is the control
691 * channel and not a usable tty interface
692 */
693 tty_unregister_device(gsm_tty_driver, base + i);
694 }
695}
696
697/**
698 * gsm_print_packet - display a frame for debug
699 * @hdr: header to print before decode
700 * @addr: address EA from the frame
701 * @cr: C/R bit seen as initiator
702 * @control: control including PF bit
703 * @data: following data bytes
704 * @dlen: length of data
705 *
706 * Displays a packet in human readable format for debugging purposes. The
707 * style is based on amateur radio LAP-B dump display.
708 */
709
710static void gsm_print_packet(const char *hdr, int addr, int cr,
711 u8 control, const u8 *data, int dlen)
712{
713 if (!(debug & DBG_DUMP))
714 return;
715 /* Only show user payload frames if debug & DBG_PAYLOAD */
716 if (!(debug & DBG_PAYLOAD) && addr != 0)
717 if ((control & ~PF) == UI || (control & ~PF) == UIH)
718 return;
719
720 pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
721
722 switch (control & ~PF) {
723 case SABM:
724 pr_cont("SABM");
725 break;
726 case UA:
727 pr_cont("UA");
728 break;
729 case DISC:
730 pr_cont("DISC");
731 break;
732 case DM:
733 pr_cont("DM");
734 break;
735 case UI:
736 pr_cont("UI");
737 break;
738 case UIH:
739 pr_cont("UIH");
740 break;
741 default:
742 if (!(control & 0x01)) {
743 pr_cont("I N(S)%d N(R)%d",
744 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
745 } else switch (control & 0x0F) {
746 case RR:
747 pr_cont("RR(%d)", (control & 0xE0) >> 5);
748 break;
749 case RNR:
750 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
751 break;
752 case REJ:
753 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
754 break;
755 default:
756 pr_cont("[%02X]", control);
757 }
758 }
759
760 if (control & PF)
761 pr_cont("(P)");
762 else
763 pr_cont("(F)");
764
765 gsm_hex_dump_bytes(NULL, data, dlen);
766}
767
768
769/*
770 * Link level transmission side
771 */
772
773/**
774 * gsm_stuff_frame - bytestuff a packet
775 * @input: input buffer
776 * @output: output buffer
777 * @len: length of input
778 *
779 * Expand a buffer by bytestuffing it. The worst case size change
780 * is doubling and the caller is responsible for handing out
781 * suitable sized buffers.
782 */
783
784static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
785{
786 int olen = 0;
787 while (len--) {
788 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
789 || (*input & ISO_IEC_646_MASK) == XON
790 || (*input & ISO_IEC_646_MASK) == XOFF) {
791 *output++ = GSM1_ESCAPE;
792 *output++ = *input++ ^ GSM1_ESCAPE_BITS;
793 olen++;
794 } else
795 *output++ = *input++;
796 olen++;
797 }
798 return olen;
799}
800
801/**
802 * gsm_send - send a control frame
803 * @gsm: our GSM mux
804 * @addr: address for control frame
805 * @cr: command/response bit seen as initiator
806 * @control: control byte including PF bit
807 *
808 * Format up and transmit a control frame. These should be transmitted
809 * ahead of data when they are needed.
810 */
811static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
812{
813 struct gsm_msg *msg;
814 u8 *dp;
815 int ocr;
816 unsigned long flags;
817
818 msg = gsm_data_alloc(gsm, addr, 0, control);
819 if (!msg)
820 return -ENOMEM;
821
822 /* toggle C/R coding if not initiator */
823 ocr = cr ^ (gsm->initiator ? 0 : 1);
824
825 msg->data -= 3;
826 dp = msg->data;
827 *dp++ = (addr << 2) | (ocr << 1) | EA;
828 *dp++ = control;
829
830 if (gsm->encoding == GSM_BASIC_OPT)
831 *dp++ = EA; /* Length of data = 0 */
832
833 *dp = 0xFF - gsm_fcs_add_block(INIT_FCS, msg->data, dp - msg->data);
834 msg->len = (dp - msg->data) + 1;
835
836 gsm_print_packet("Q->", addr, cr, control, NULL, 0);
837
838 spin_lock_irqsave(&gsm->tx_lock, flags);
839 list_add_tail(&msg->list, &gsm->tx_ctrl_list);
840 gsm->tx_bytes += msg->len;
841 spin_unlock_irqrestore(&gsm->tx_lock, flags);
842 gsmld_write_trigger(gsm);
843
844 return 0;
845}
846
847/**
848 * gsm_dlci_clear_queues - remove outstanding data for a DLCI
849 * @gsm: mux
850 * @dlci: clear for this DLCI
851 *
852 * Clears the data queues for a given DLCI.
853 */
854static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci)
855{
856 struct gsm_msg *msg, *nmsg;
857 int addr = dlci->addr;
858 unsigned long flags;
859
860 /* Clear DLCI write fifo first */
861 spin_lock_irqsave(&dlci->lock, flags);
862 kfifo_reset(&dlci->fifo);
863 spin_unlock_irqrestore(&dlci->lock, flags);
864
865 /* Clear data packets in MUX write queue */
866 spin_lock_irqsave(&gsm->tx_lock, flags);
867 list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
868 if (msg->addr != addr)
869 continue;
870 gsm->tx_bytes -= msg->len;
871 list_del(&msg->list);
872 kfree(msg);
873 }
874 spin_unlock_irqrestore(&gsm->tx_lock, flags);
875}
876
877/**
878 * gsm_response - send a control response
879 * @gsm: our GSM mux
880 * @addr: address for control frame
881 * @control: control byte including PF bit
882 *
883 * Format up and transmit a link level response frame.
884 */
885
886static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
887{
888 gsm_send(gsm, addr, 0, control);
889}
890
891/**
892 * gsm_command - send a control command
893 * @gsm: our GSM mux
894 * @addr: address for control frame
895 * @control: control byte including PF bit
896 *
897 * Format up and transmit a link level command frame.
898 */
899
900static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
901{
902 gsm_send(gsm, addr, 1, control);
903}
904
905/* Data transmission */
906
907#define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
908
909/**
910 * gsm_data_alloc - allocate data frame
911 * @gsm: GSM mux
912 * @addr: DLCI address
913 * @len: length excluding header and FCS
914 * @ctrl: control byte
915 *
916 * Allocate a new data buffer for sending frames with data. Space is left
917 * at the front for header bytes but that is treated as an implementation
918 * detail and not for the high level code to use
919 */
920
921static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
922 u8 ctrl)
923{
924 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
925 GFP_ATOMIC);
926 if (m == NULL)
927 return NULL;
928 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */
929 m->len = len;
930 m->addr = addr;
931 m->ctrl = ctrl;
932 INIT_LIST_HEAD(&m->list);
933 return m;
934}
935
936/**
937 * gsm_send_packet - sends a single packet
938 * @gsm: GSM Mux
939 * @msg: packet to send
940 *
941 * The given packet is encoded and sent out. No memory is freed.
942 * The caller must hold the gsm tx lock.
943 */
944static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
945{
946 int len, ret;
947
948
949 if (gsm->encoding == GSM_BASIC_OPT) {
950 gsm->txframe[0] = GSM0_SOF;
951 memcpy(gsm->txframe + 1, msg->data, msg->len);
952 gsm->txframe[msg->len + 1] = GSM0_SOF;
953 len = msg->len + 2;
954 } else {
955 gsm->txframe[0] = GSM1_SOF;
956 len = gsm_stuff_frame(msg->data, gsm->txframe + 1, msg->len);
957 gsm->txframe[len + 1] = GSM1_SOF;
958 len += 2;
959 }
960
961 if (debug & DBG_DATA)
962 gsm_hex_dump_bytes(__func__, gsm->txframe, len);
963 gsm_print_packet("-->", msg->addr, gsm->initiator, msg->ctrl, msg->data,
964 msg->len);
965
966 ret = gsmld_output(gsm, gsm->txframe, len);
967 if (ret <= 0)
968 return ret;
969 /* FIXME: Can eliminate one SOF in many more cases */
970 gsm->tx_bytes -= msg->len;
971
972 return 0;
973}
974
975/**
976 * gsm_is_flow_ctrl_msg - checks if flow control message
977 * @msg: message to check
978 *
979 * Returns true if the given message is a flow control command of the
980 * control channel. False is returned in any other case.
981 */
982static bool gsm_is_flow_ctrl_msg(struct gsm_msg *msg)
983{
984 unsigned int cmd;
985
986 if (msg->addr > 0)
987 return false;
988
989 switch (msg->ctrl & ~PF) {
990 case UI:
991 case UIH:
992 cmd = 0;
993 if (gsm_read_ea_val(&cmd, msg->data + 2, msg->len - 2) < 1)
994 break;
995 switch (cmd & ~PF) {
996 case CMD_FCOFF:
997 case CMD_FCON:
998 return true;
999 }
1000 break;
1001 }
1002
1003 return false;
1004}
1005
1006/**
1007 * gsm_data_kick - poke the queue
1008 * @gsm: GSM Mux
1009 *
1010 * The tty device has called us to indicate that room has appeared in
1011 * the transmit queue. Ram more data into the pipe if we have any.
1012 * If we have been flow-stopped by a CMD_FCOFF, then we can only
1013 * send messages on DLCI0 until CMD_FCON. The caller must hold
1014 * the gsm tx lock.
1015 */
1016static int gsm_data_kick(struct gsm_mux *gsm)
1017{
1018 struct gsm_msg *msg, *nmsg;
1019 struct gsm_dlci *dlci;
1020 int ret;
1021
1022 clear_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
1023
1024 /* Serialize control messages and control channel messages first */
1025 list_for_each_entry_safe(msg, nmsg, &gsm->tx_ctrl_list, list) {
1026 if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg))
1027 continue;
1028 ret = gsm_send_packet(gsm, msg);
1029 switch (ret) {
1030 case -ENOSPC:
1031 return -ENOSPC;
1032 case -ENODEV:
1033 /* ldisc not open */
1034 gsm->tx_bytes -= msg->len;
1035 list_del(&msg->list);
1036 kfree(msg);
1037 continue;
1038 default:
1039 if (ret >= 0) {
1040 list_del(&msg->list);
1041 kfree(msg);
1042 }
1043 break;
1044 }
1045 }
1046
1047 if (gsm->constipated)
1048 return -EAGAIN;
1049
1050 /* Serialize other channels */
1051 if (list_empty(&gsm->tx_data_list))
1052 return 0;
1053 list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
1054 dlci = gsm->dlci[msg->addr];
1055 /* Send only messages for DLCIs with valid state */
1056 if (dlci->state != DLCI_OPEN) {
1057 gsm->tx_bytes -= msg->len;
1058 list_del(&msg->list);
1059 kfree(msg);
1060 continue;
1061 }
1062 ret = gsm_send_packet(gsm, msg);
1063 switch (ret) {
1064 case -ENOSPC:
1065 return -ENOSPC;
1066 case -ENODEV:
1067 /* ldisc not open */
1068 gsm->tx_bytes -= msg->len;
1069 list_del(&msg->list);
1070 kfree(msg);
1071 continue;
1072 default:
1073 if (ret >= 0) {
1074 list_del(&msg->list);
1075 kfree(msg);
1076 }
1077 break;
1078 }
1079 }
1080
1081 return 1;
1082}
1083
1084/**
1085 * __gsm_data_queue - queue a UI or UIH frame
1086 * @dlci: DLCI sending the data
1087 * @msg: message queued
1088 *
1089 * Add data to the transmit queue and try and get stuff moving
1090 * out of the mux tty if not already doing so. The Caller must hold
1091 * the gsm tx lock.
1092 */
1093
1094static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
1095{
1096 struct gsm_mux *gsm = dlci->gsm;
1097 u8 *dp = msg->data;
1098 u8 *fcs = dp + msg->len;
1099
1100 /* Fill in the header */
1101 if (gsm->encoding == GSM_BASIC_OPT) {
1102 if (msg->len < 128)
1103 *--dp = (msg->len << 1) | EA;
1104 else {
1105 *--dp = (msg->len >> 7); /* bits 7 - 15 */
1106 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
1107 }
1108 }
1109
1110 *--dp = msg->ctrl;
1111 if (gsm->initiator)
1112 *--dp = (msg->addr << 2) | CR | EA;
1113 else
1114 *--dp = (msg->addr << 2) | EA;
1115 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
1116 /* Ugly protocol layering violation */
1117 if (msg->ctrl == UI || msg->ctrl == (UI|PF))
1118 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
1119 *fcs = 0xFF - *fcs;
1120
1121 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
1122 msg->data, msg->len);
1123
1124 /* Move the header back and adjust the length, also allow for the FCS
1125 now tacked on the end */
1126 msg->len += (msg->data - dp) + 1;
1127 msg->data = dp;
1128
1129 /* Add to the actual output queue */
1130 switch (msg->ctrl & ~PF) {
1131 case UI:
1132 case UIH:
1133 if (msg->addr > 0) {
1134 list_add_tail(&msg->list, &gsm->tx_data_list);
1135 break;
1136 }
1137 fallthrough;
1138 default:
1139 list_add_tail(&msg->list, &gsm->tx_ctrl_list);
1140 break;
1141 }
1142 gsm->tx_bytes += msg->len;
1143
1144 gsmld_write_trigger(gsm);
1145 mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
1146}
1147
1148/**
1149 * gsm_data_queue - queue a UI or UIH frame
1150 * @dlci: DLCI sending the data
1151 * @msg: message queued
1152 *
1153 * Add data to the transmit queue and try and get stuff moving
1154 * out of the mux tty if not already doing so. Take the
1155 * the gsm tx lock and dlci lock.
1156 */
1157
1158static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
1159{
1160 unsigned long flags;
1161 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
1162 __gsm_data_queue(dlci, msg);
1163 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
1164}
1165
1166/**
1167 * gsm_dlci_data_output - try and push data out of a DLCI
1168 * @gsm: mux
1169 * @dlci: the DLCI to pull data from
1170 *
1171 * Pull data from a DLCI and send it into the transmit queue if there
1172 * is data. Keep to the MRU of the mux. This path handles the usual tty
1173 * interface which is a byte stream with optional modem data.
1174 *
1175 * Caller must hold the tx_lock of the mux.
1176 */
1177
1178static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
1179{
1180 struct gsm_msg *msg;
1181 u8 *dp;
1182 int h, len, size;
1183
1184 /* for modem bits without break data */
1185 h = ((dlci->adaption == 1) ? 0 : 1);
1186
1187 len = kfifo_len(&dlci->fifo);
1188 if (len == 0)
1189 return 0;
1190
1191 /* MTU/MRU count only the data bits but watch adaption mode */
1192 if ((len + h) > dlci->mtu)
1193 len = dlci->mtu - h;
1194
1195 size = len + h;
1196
1197 msg = gsm_data_alloc(gsm, dlci->addr, size, dlci->ftype);
1198 if (!msg)
1199 return -ENOMEM;
1200 dp = msg->data;
1201 switch (dlci->adaption) {
1202 case 1: /* Unstructured */
1203 break;
1204 case 2: /* Unstructured with modem bits.
1205 * Always one byte as we never send inline break data
1206 */
1207 *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
1208 break;
1209 default:
1210 pr_err("%s: unsupported adaption %d\n", __func__,
1211 dlci->adaption);
1212 break;
1213 }
1214
1215 WARN_ON(len != kfifo_out_locked(&dlci->fifo, dp, len,
1216 &dlci->lock));
1217
1218 /* Notify upper layer about available send space. */
1219 tty_port_tty_wakeup(&dlci->port);
1220
1221 __gsm_data_queue(dlci, msg);
1222 /* Bytes of data we used up */
1223 return size;
1224}
1225
1226/**
1227 * gsm_dlci_data_output_framed - try and push data out of a DLCI
1228 * @gsm: mux
1229 * @dlci: the DLCI to pull data from
1230 *
1231 * Pull data from a DLCI and send it into the transmit queue if there
1232 * is data. Keep to the MRU of the mux. This path handles framed data
1233 * queued as skbuffs to the DLCI.
1234 *
1235 * Caller must hold the tx_lock of the mux.
1236 */
1237
1238static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
1239 struct gsm_dlci *dlci)
1240{
1241 struct gsm_msg *msg;
1242 u8 *dp;
1243 int len, size;
1244 int last = 0, first = 0;
1245 int overhead = 0;
1246
1247 /* One byte per frame is used for B/F flags */
1248 if (dlci->adaption == 4)
1249 overhead = 1;
1250
1251 /* dlci->skb is locked by tx_lock */
1252 if (dlci->skb == NULL) {
1253 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
1254 if (dlci->skb == NULL)
1255 return 0;
1256 first = 1;
1257 }
1258 len = dlci->skb->len + overhead;
1259
1260 /* MTU/MRU count only the data bits */
1261 if (len > dlci->mtu) {
1262 if (dlci->adaption == 3) {
1263 /* Over long frame, bin it */
1264 dev_kfree_skb_any(dlci->skb);
1265 dlci->skb = NULL;
1266 return 0;
1267 }
1268 len = dlci->mtu;
1269 } else
1270 last = 1;
1271
1272 size = len + overhead;
1273 msg = gsm_data_alloc(gsm, dlci->addr, size, dlci->ftype);
1274 if (msg == NULL) {
1275 skb_queue_tail(&dlci->skb_list, dlci->skb);
1276 dlci->skb = NULL;
1277 return -ENOMEM;
1278 }
1279 dp = msg->data;
1280
1281 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
1282 /* Flag byte to carry the start/end info */
1283 *dp++ = last << 7 | first << 6 | 1; /* EA */
1284 len--;
1285 }
1286 memcpy(dp, dlci->skb->data, len);
1287 skb_pull(dlci->skb, len);
1288 __gsm_data_queue(dlci, msg);
1289 if (last) {
1290 dev_kfree_skb_any(dlci->skb);
1291 dlci->skb = NULL;
1292 }
1293 return size;
1294}
1295
1296/**
1297 * gsm_dlci_modem_output - try and push modem status out of a DLCI
1298 * @gsm: mux
1299 * @dlci: the DLCI to pull modem status from
1300 * @brk: break signal
1301 *
1302 * Push an empty frame in to the transmit queue to update the modem status
1303 * bits and to transmit an optional break.
1304 *
1305 * Caller must hold the tx_lock of the mux.
1306 */
1307
1308static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
1309 u8 brk)
1310{
1311 u8 *dp = NULL;
1312 struct gsm_msg *msg;
1313 int size = 0;
1314
1315 /* for modem bits without break data */
1316 switch (dlci->adaption) {
1317 case 1: /* Unstructured */
1318 break;
1319 case 2: /* Unstructured with modem bits. */
1320 size++;
1321 if (brk > 0)
1322 size++;
1323 break;
1324 default:
1325 pr_err("%s: unsupported adaption %d\n", __func__,
1326 dlci->adaption);
1327 return -EINVAL;
1328 }
1329
1330 msg = gsm_data_alloc(gsm, dlci->addr, size, dlci->ftype);
1331 if (!msg) {
1332 pr_err("%s: gsm_data_alloc error", __func__);
1333 return -ENOMEM;
1334 }
1335 dp = msg->data;
1336 switch (dlci->adaption) {
1337 case 1: /* Unstructured */
1338 break;
1339 case 2: /* Unstructured with modem bits. */
1340 if (brk == 0) {
1341 *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
1342 } else {
1343 *dp++ = gsm_encode_modem(dlci) << 1;
1344 *dp++ = (brk << 4) | 2 | EA; /* Length, Break, EA */
1345 }
1346 break;
1347 default:
1348 /* Handled above */
1349 break;
1350 }
1351
1352 __gsm_data_queue(dlci, msg);
1353 return size;
1354}
1355
1356/**
1357 * gsm_dlci_data_sweep - look for data to send
1358 * @gsm: the GSM mux
1359 *
1360 * Sweep the GSM mux channels in priority order looking for ones with
1361 * data to send. We could do with optimising this scan a bit. We aim
1362 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
1363 * TX_THRESH_LO we get called again
1364 *
1365 * FIXME: We should round robin between groups and in theory you can
1366 * renegotiate DLCI priorities with optional stuff. Needs optimising.
1367 */
1368
1369static int gsm_dlci_data_sweep(struct gsm_mux *gsm)
1370{
1371 /* Priority ordering: We should do priority with RR of the groups */
1372 int i, len, ret = 0;
1373 bool sent;
1374 struct gsm_dlci *dlci;
1375
1376 while (gsm->tx_bytes < TX_THRESH_HI) {
1377 for (sent = false, i = 1; i < NUM_DLCI; i++) {
1378 dlci = gsm->dlci[i];
1379 /* skip unused or blocked channel */
1380 if (!dlci || dlci->constipated)
1381 continue;
1382 /* skip channels with invalid state */
1383 if (dlci->state != DLCI_OPEN)
1384 continue;
1385 /* count the sent data per adaption */
1386 if (dlci->adaption < 3 && !dlci->net)
1387 len = gsm_dlci_data_output(gsm, dlci);
1388 else
1389 len = gsm_dlci_data_output_framed(gsm, dlci);
1390 /* on error exit */
1391 if (len < 0)
1392 return ret;
1393 if (len > 0) {
1394 ret++;
1395 sent = true;
1396 /* The lower DLCs can starve the higher DLCs! */
1397 break;
1398 }
1399 /* try next */
1400 }
1401 if (!sent)
1402 break;
1403 }
1404
1405 return ret;
1406}
1407
1408/**
1409 * gsm_dlci_data_kick - transmit if possible
1410 * @dlci: DLCI to kick
1411 *
1412 * Transmit data from this DLCI if the queue is empty. We can't rely on
1413 * a tty wakeup except when we filled the pipe so we need to fire off
1414 * new data ourselves in other cases.
1415 */
1416
1417static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
1418{
1419 unsigned long flags;
1420 int sweep;
1421
1422 if (dlci->constipated)
1423 return;
1424
1425 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
1426 /* If we have nothing running then we need to fire up */
1427 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
1428 if (dlci->gsm->tx_bytes == 0) {
1429 if (dlci->net)
1430 gsm_dlci_data_output_framed(dlci->gsm, dlci);
1431 else
1432 gsm_dlci_data_output(dlci->gsm, dlci);
1433 }
1434 if (sweep)
1435 gsm_dlci_data_sweep(dlci->gsm);
1436 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
1437}
1438
1439/*
1440 * Control message processing
1441 */
1442
1443
1444/**
1445 * gsm_control_command - send a command frame to a control
1446 * @gsm: gsm channel
1447 * @cmd: the command to use
1448 * @data: data to follow encoded info
1449 * @dlen: length of data
1450 *
1451 * Encode up and queue a UI/UIH frame containing our command.
1452 */
1453static int gsm_control_command(struct gsm_mux *gsm, int cmd, const u8 *data,
1454 int dlen)
1455{
1456 struct gsm_msg *msg;
1457 struct gsm_dlci *dlci = gsm->dlci[0];
1458
1459 msg = gsm_data_alloc(gsm, 0, dlen + 2, dlci->ftype);
1460 if (msg == NULL)
1461 return -ENOMEM;
1462
1463 msg->data[0] = (cmd << 1) | CR | EA; /* Set C/R */
1464 msg->data[1] = (dlen << 1) | EA;
1465 memcpy(msg->data + 2, data, dlen);
1466 gsm_data_queue(dlci, msg);
1467
1468 return 0;
1469}
1470
1471/**
1472 * gsm_control_reply - send a response frame to a control
1473 * @gsm: gsm channel
1474 * @cmd: the command to use
1475 * @data: data to follow encoded info
1476 * @dlen: length of data
1477 *
1478 * Encode up and queue a UI/UIH frame containing our response.
1479 */
1480
1481static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
1482 int dlen)
1483{
1484 struct gsm_msg *msg;
1485 struct gsm_dlci *dlci = gsm->dlci[0];
1486
1487 msg = gsm_data_alloc(gsm, 0, dlen + 2, dlci->ftype);
1488 if (msg == NULL)
1489 return;
1490 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
1491 msg->data[1] = (dlen << 1) | EA;
1492 memcpy(msg->data + 2, data, dlen);
1493 gsm_data_queue(dlci, msg);
1494}
1495
1496/**
1497 * gsm_process_modem - process received modem status
1498 * @tty: virtual tty bound to the DLCI
1499 * @dlci: DLCI to affect
1500 * @modem: modem bits (full EA)
1501 * @slen: number of signal octets
1502 *
1503 * Used when a modem control message or line state inline in adaption
1504 * layer 2 is processed. Sort out the local modem state and throttles
1505 */
1506
1507static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1508 u32 modem, int slen)
1509{
1510 int mlines = 0;
1511 u8 brk = 0;
1512 int fc;
1513
1514 /* The modem status command can either contain one octet (V.24 signals)
1515 * or two octets (V.24 signals + break signals). This is specified in
1516 * section 5.4.6.3.7 of the 07.10 mux spec.
1517 */
1518
1519 if (slen == 1)
1520 modem = modem & 0x7f;
1521 else {
1522 brk = modem & 0x7f;
1523 modem = (modem >> 7) & 0x7f;
1524 }
1525
1526 /* Flow control/ready to communicate */
1527 fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1528 if (fc && !dlci->constipated) {
1529 /* Need to throttle our output on this device */
1530 dlci->constipated = true;
1531 } else if (!fc && dlci->constipated) {
1532 dlci->constipated = false;
1533 gsm_dlci_data_kick(dlci);
1534 }
1535
1536 /* Map modem bits */
1537 if (modem & MDM_RTC)
1538 mlines |= TIOCM_DSR | TIOCM_DTR;
1539 if (modem & MDM_RTR)
1540 mlines |= TIOCM_RTS | TIOCM_CTS;
1541 if (modem & MDM_IC)
1542 mlines |= TIOCM_RI;
1543 if (modem & MDM_DV)
1544 mlines |= TIOCM_CD;
1545
1546 /* Carrier drop -> hangup */
1547 if (tty) {
1548 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1549 if (!C_CLOCAL(tty))
1550 tty_hangup(tty);
1551 }
1552 if (brk & 0x01)
1553 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1554 dlci->modem_rx = mlines;
1555 wake_up_interruptible(&dlci->gsm->event);
1556}
1557
1558/**
1559 * gsm_process_negotiation - process received parameters
1560 * @gsm: GSM channel
1561 * @addr: DLCI address
1562 * @cr: command/response
1563 * @params: encoded parameters from the parameter negotiation message
1564 *
1565 * Used when the response for our parameter negotiation command was
1566 * received.
1567 */
1568static int gsm_process_negotiation(struct gsm_mux *gsm, unsigned int addr,
1569 unsigned int cr,
1570 const struct gsm_dlci_param_bits *params)
1571{
1572 struct gsm_dlci *dlci = gsm->dlci[addr];
1573 unsigned int ftype, i, adaption, prio, n1, k;
1574
1575 i = FIELD_GET(PN_I_CL_FIELD_FTYPE, params->i_cl_bits);
1576 adaption = FIELD_GET(PN_I_CL_FIELD_ADAPTION, params->i_cl_bits) + 1;
1577 prio = FIELD_GET(PN_P_FIELD_PRIO, params->p_bits);
1578 n1 = FIELD_GET(PN_N_FIELD_N1, get_unaligned_le16(¶ms->n_bits));
1579 k = FIELD_GET(PN_K_FIELD_K, params->k_bits);
1580
1581 if (n1 < MIN_MTU) {
1582 if (debug & DBG_ERRORS)
1583 pr_info("%s N1 out of range in PN\n", __func__);
1584 return -EINVAL;
1585 }
1586
1587 switch (i) {
1588 case 0x00:
1589 ftype = UIH;
1590 break;
1591 case 0x01:
1592 ftype = UI;
1593 break;
1594 case 0x02: /* I frames are not supported */
1595 if (debug & DBG_ERRORS)
1596 pr_info("%s unsupported I frame request in PN\n",
1597 __func__);
1598 gsm->unsupported++;
1599 return -EINVAL;
1600 default:
1601 if (debug & DBG_ERRORS)
1602 pr_info("%s i out of range in PN\n", __func__);
1603 return -EINVAL;
1604 }
1605
1606 if (!cr && gsm->initiator) {
1607 if (adaption != dlci->adaption) {
1608 if (debug & DBG_ERRORS)
1609 pr_info("%s invalid adaption %d in PN\n",
1610 __func__, adaption);
1611 return -EINVAL;
1612 }
1613 if (prio != dlci->prio) {
1614 if (debug & DBG_ERRORS)
1615 pr_info("%s invalid priority %d in PN",
1616 __func__, prio);
1617 return -EINVAL;
1618 }
1619 if (n1 > gsm->mru || n1 > dlci->mtu) {
1620 /* We requested a frame size but the other party wants
1621 * to send larger frames. The standard allows only a
1622 * smaller response value than requested (5.4.6.3.1).
1623 */
1624 if (debug & DBG_ERRORS)
1625 pr_info("%s invalid N1 %d in PN\n", __func__,
1626 n1);
1627 return -EINVAL;
1628 }
1629 dlci->mtu = n1;
1630 if (ftype != dlci->ftype) {
1631 if (debug & DBG_ERRORS)
1632 pr_info("%s invalid i %d in PN\n", __func__, i);
1633 return -EINVAL;
1634 }
1635 if (ftype != UI && ftype != UIH && k > dlci->k) {
1636 if (debug & DBG_ERRORS)
1637 pr_info("%s invalid k %d in PN\n", __func__, k);
1638 return -EINVAL;
1639 }
1640 dlci->k = k;
1641 } else if (cr && !gsm->initiator) {
1642 /* Only convergence layer type 1 and 2 are supported. */
1643 if (adaption != 1 && adaption != 2) {
1644 if (debug & DBG_ERRORS)
1645 pr_info("%s invalid adaption %d in PN\n",
1646 __func__, adaption);
1647 return -EINVAL;
1648 }
1649 dlci->adaption = adaption;
1650 if (n1 > gsm->mru) {
1651 /* Propose a smaller value */
1652 dlci->mtu = gsm->mru;
1653 } else if (n1 > MAX_MTU) {
1654 /* Propose a smaller value */
1655 dlci->mtu = MAX_MTU;
1656 } else {
1657 dlci->mtu = n1;
1658 }
1659 dlci->prio = prio;
1660 dlci->ftype = ftype;
1661 dlci->k = k;
1662 } else {
1663 return -EINVAL;
1664 }
1665
1666 return 0;
1667}
1668
1669/**
1670 * gsm_control_modem - modem status received
1671 * @gsm: GSM channel
1672 * @data: data following command
1673 * @clen: command length
1674 *
1675 * We have received a modem status control message. This is used by
1676 * the GSM mux protocol to pass virtual modem line status and optionally
1677 * to indicate break signals. Unpack it, convert to Linux representation
1678 * and if need be stuff a break message down the tty.
1679 */
1680
1681static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1682{
1683 unsigned int addr = 0;
1684 unsigned int modem = 0;
1685 struct gsm_dlci *dlci;
1686 int len = clen;
1687 int cl = clen;
1688 const u8 *dp = data;
1689 struct tty_struct *tty;
1690
1691 len = gsm_read_ea_val(&addr, data, cl);
1692 if (len < 1)
1693 return;
1694
1695 addr >>= 1;
1696 /* Closed port, or invalid ? */
1697 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1698 return;
1699 dlci = gsm->dlci[addr];
1700
1701 /* Must be at least one byte following the EA */
1702 if ((cl - len) < 1)
1703 return;
1704
1705 dp += len;
1706 cl -= len;
1707
1708 /* get the modem status */
1709 len = gsm_read_ea_val(&modem, dp, cl);
1710 if (len < 1)
1711 return;
1712
1713 tty = tty_port_tty_get(&dlci->port);
1714 gsm_process_modem(tty, dlci, modem, cl);
1715 if (tty) {
1716 tty_wakeup(tty);
1717 tty_kref_put(tty);
1718 }
1719 gsm_control_reply(gsm, CMD_MSC, data, clen);
1720}
1721
1722/**
1723 * gsm_control_negotiation - parameter negotiation received
1724 * @gsm: GSM channel
1725 * @cr: command/response flag
1726 * @data: data following command
1727 * @dlen: data length
1728 *
1729 * We have received a parameter negotiation message. This is used by
1730 * the GSM mux protocol to configure protocol parameters for a new DLCI.
1731 */
1732static void gsm_control_negotiation(struct gsm_mux *gsm, unsigned int cr,
1733 const u8 *data, unsigned int dlen)
1734{
1735 unsigned int addr;
1736 struct gsm_dlci_param_bits pn_reply;
1737 struct gsm_dlci *dlci;
1738 struct gsm_dlci_param_bits *params;
1739
1740 if (dlen < sizeof(struct gsm_dlci_param_bits)) {
1741 gsm->open_error++;
1742 return;
1743 }
1744
1745 /* Invalid DLCI? */
1746 params = (struct gsm_dlci_param_bits *)data;
1747 addr = FIELD_GET(PN_D_FIELD_DLCI, params->d_bits);
1748 if (addr == 0 || addr >= NUM_DLCI || !gsm->dlci[addr]) {
1749 gsm->open_error++;
1750 return;
1751 }
1752 dlci = gsm->dlci[addr];
1753
1754 /* Too late for parameter negotiation? */
1755 if ((!cr && dlci->state == DLCI_OPENING) || dlci->state == DLCI_OPEN) {
1756 gsm->open_error++;
1757 return;
1758 }
1759
1760 /* Process the received parameters */
1761 if (gsm_process_negotiation(gsm, addr, cr, params) != 0) {
1762 /* Negotiation failed. Close the link. */
1763 if (debug & DBG_ERRORS)
1764 pr_info("%s PN failed\n", __func__);
1765 gsm->open_error++;
1766 gsm_dlci_close(dlci);
1767 return;
1768 }
1769
1770 if (cr) {
1771 /* Reply command with accepted parameters. */
1772 if (gsm_encode_params(dlci, &pn_reply) == 0)
1773 gsm_control_reply(gsm, CMD_PN, (const u8 *)&pn_reply,
1774 sizeof(pn_reply));
1775 else if (debug & DBG_ERRORS)
1776 pr_info("%s PN invalid\n", __func__);
1777 } else if (dlci->state == DLCI_CONFIGURE) {
1778 /* Proceed with link setup by sending SABM before UA */
1779 dlci->state = DLCI_OPENING;
1780 gsm_command(gsm, dlci->addr, SABM|PF);
1781 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1782 } else {
1783 if (debug & DBG_ERRORS)
1784 pr_info("%s PN in invalid state\n", __func__);
1785 gsm->open_error++;
1786 }
1787}
1788
1789/**
1790 * gsm_control_rls - remote line status
1791 * @gsm: GSM channel
1792 * @data: data bytes
1793 * @clen: data length
1794 *
1795 * The modem sends us a two byte message on the control channel whenever
1796 * it wishes to send us an error state from the virtual link. Stuff
1797 * this into the uplink tty if present
1798 */
1799
1800static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1801{
1802 struct tty_port *port;
1803 unsigned int addr = 0;
1804 u8 bits;
1805 int len = clen;
1806 const u8 *dp = data;
1807
1808 while (gsm_read_ea(&addr, *dp++) == 0) {
1809 len--;
1810 if (len == 0)
1811 return;
1812 }
1813 /* Must be at least one byte following ea */
1814 len--;
1815 if (len <= 0)
1816 return;
1817 addr >>= 1;
1818 /* Closed port, or invalid ? */
1819 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1820 return;
1821 /* No error ? */
1822 bits = *dp;
1823 if ((bits & 1) == 0)
1824 return;
1825
1826 port = &gsm->dlci[addr]->port;
1827
1828 if (bits & 2)
1829 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1830 if (bits & 4)
1831 tty_insert_flip_char(port, 0, TTY_PARITY);
1832 if (bits & 8)
1833 tty_insert_flip_char(port, 0, TTY_FRAME);
1834
1835 tty_flip_buffer_push(port);
1836
1837 gsm_control_reply(gsm, CMD_RLS, data, clen);
1838}
1839
1840static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1841
1842/**
1843 * gsm_control_message - DLCI 0 control processing
1844 * @gsm: our GSM mux
1845 * @command: the command EA
1846 * @data: data beyond the command/length EAs
1847 * @clen: length
1848 *
1849 * Input processor for control messages from the other end of the link.
1850 * Processes the incoming request and queues a response frame or an
1851 * NSC response if not supported
1852 */
1853
1854static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1855 const u8 *data, int clen)
1856{
1857 u8 buf[1];
1858
1859 switch (command) {
1860 case CMD_CLD: {
1861 struct gsm_dlci *dlci = gsm->dlci[0];
1862 /* Modem wishes to close down */
1863 if (dlci) {
1864 dlci->dead = true;
1865 gsm->dead = true;
1866 gsm_dlci_begin_close(dlci);
1867 }
1868 }
1869 break;
1870 case CMD_TEST:
1871 /* Modem wishes to test, reply with the data */
1872 gsm_control_reply(gsm, CMD_TEST, data, clen);
1873 break;
1874 case CMD_FCON:
1875 /* Modem can accept data again */
1876 gsm->constipated = false;
1877 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1878 /* Kick the link in case it is idling */
1879 gsmld_write_trigger(gsm);
1880 break;
1881 case CMD_FCOFF:
1882 /* Modem wants us to STFU */
1883 gsm->constipated = true;
1884 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1885 break;
1886 case CMD_MSC:
1887 /* Out of band modem line change indicator for a DLCI */
1888 gsm_control_modem(gsm, data, clen);
1889 break;
1890 case CMD_RLS:
1891 /* Out of band error reception for a DLCI */
1892 gsm_control_rls(gsm, data, clen);
1893 break;
1894 case CMD_PSC:
1895 /* Modem wishes to enter power saving state */
1896 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1897 break;
1898 /* Optional commands */
1899 case CMD_PN:
1900 /* Modem sends a parameter negotiation command */
1901 gsm_control_negotiation(gsm, 1, data, clen);
1902 break;
1903 /* Optional unsupported commands */
1904 case CMD_RPN: /* Remote port negotiation */
1905 case CMD_SNC: /* Service negotiation command */
1906 gsm->unsupported++;
1907 fallthrough;
1908 default:
1909 /* Reply to bad commands with an NSC */
1910 buf[0] = command;
1911 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1912 break;
1913 }
1914}
1915
1916/**
1917 * gsm_control_response - process a response to our control
1918 * @gsm: our GSM mux
1919 * @command: the command (response) EA
1920 * @data: data beyond the command/length EA
1921 * @clen: length
1922 *
1923 * Process a response to an outstanding command. We only allow a single
1924 * control message in flight so this is fairly easy. All the clean up
1925 * is done by the caller, we just update the fields, flag it as done
1926 * and return
1927 */
1928
1929static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1930 const u8 *data, int clen)
1931{
1932 struct gsm_control *ctrl;
1933 struct gsm_dlci *dlci;
1934 unsigned long flags;
1935
1936 spin_lock_irqsave(&gsm->control_lock, flags);
1937
1938 ctrl = gsm->pending_cmd;
1939 dlci = gsm->dlci[0];
1940 command |= 1;
1941 /* Does the reply match our command */
1942 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1943 /* Our command was replied to, kill the retry timer */
1944 del_timer(&gsm->t2_timer);
1945 gsm->pending_cmd = NULL;
1946 /* Rejected by the other end */
1947 if (command == CMD_NSC)
1948 ctrl->error = -EOPNOTSUPP;
1949 ctrl->done = 1;
1950 wake_up(&gsm->event);
1951 /* Or did we receive the PN response to our PN command */
1952 } else if (command == CMD_PN) {
1953 gsm_control_negotiation(gsm, 0, data, clen);
1954 /* Or did we receive the TEST response to our TEST command */
1955 } else if (command == CMD_TEST && clen == 1 && *data == gsm->ka_num) {
1956 gsm->ka_retries = -1; /* trigger new keep-alive message */
1957 if (dlci && !dlci->dead)
1958 mod_timer(&gsm->ka_timer, jiffies + gsm->keep_alive * HZ / 100);
1959 }
1960 spin_unlock_irqrestore(&gsm->control_lock, flags);
1961}
1962
1963/**
1964 * gsm_control_keep_alive - check timeout or start keep-alive
1965 * @t: timer contained in our gsm object
1966 *
1967 * Called off the keep-alive timer expiry signaling that our link
1968 * partner is not responding anymore. Link will be closed.
1969 * This is also called to startup our timer.
1970 */
1971
1972static void gsm_control_keep_alive(struct timer_list *t)
1973{
1974 struct gsm_mux *gsm = from_timer(gsm, t, ka_timer);
1975 unsigned long flags;
1976
1977 spin_lock_irqsave(&gsm->control_lock, flags);
1978 if (gsm->ka_num && gsm->ka_retries == 0) {
1979 /* Keep-alive expired -> close the link */
1980 if (debug & DBG_ERRORS)
1981 pr_debug("%s keep-alive timed out\n", __func__);
1982 spin_unlock_irqrestore(&gsm->control_lock, flags);
1983 if (gsm->dlci[0])
1984 gsm_dlci_begin_close(gsm->dlci[0]);
1985 return;
1986 } else if (gsm->keep_alive && gsm->dlci[0] && !gsm->dlci[0]->dead) {
1987 if (gsm->ka_retries > 0) {
1988 /* T2 expired for keep-alive -> resend */
1989 gsm->ka_retries--;
1990 } else {
1991 /* Start keep-alive timer */
1992 gsm->ka_num++;
1993 if (!gsm->ka_num)
1994 gsm->ka_num++;
1995 gsm->ka_retries = (signed int)gsm->n2;
1996 }
1997 gsm_control_command(gsm, CMD_TEST, &gsm->ka_num,
1998 sizeof(gsm->ka_num));
1999 mod_timer(&gsm->ka_timer,
2000 jiffies + gsm->t2 * HZ / 100);
2001 }
2002 spin_unlock_irqrestore(&gsm->control_lock, flags);
2003}
2004
2005/**
2006 * gsm_control_transmit - send control packet
2007 * @gsm: gsm mux
2008 * @ctrl: frame to send
2009 *
2010 * Send out a pending control command (called under control lock)
2011 */
2012
2013static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
2014{
2015 gsm_control_command(gsm, ctrl->cmd, ctrl->data, ctrl->len);
2016}
2017
2018/**
2019 * gsm_control_retransmit - retransmit a control frame
2020 * @t: timer contained in our gsm object
2021 *
2022 * Called off the T2 timer expiry in order to retransmit control frames
2023 * that have been lost in the system somewhere. The control_lock protects
2024 * us from colliding with another sender or a receive completion event.
2025 * In that situation the timer may still occur in a small window but
2026 * gsm->pending_cmd will be NULL and we just let the timer expire.
2027 */
2028
2029static void gsm_control_retransmit(struct timer_list *t)
2030{
2031 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
2032 struct gsm_control *ctrl;
2033 unsigned long flags;
2034 spin_lock_irqsave(&gsm->control_lock, flags);
2035 ctrl = gsm->pending_cmd;
2036 if (ctrl) {
2037 if (gsm->cretries == 0 || !gsm->dlci[0] || gsm->dlci[0]->dead) {
2038 gsm->pending_cmd = NULL;
2039 ctrl->error = -ETIMEDOUT;
2040 ctrl->done = 1;
2041 spin_unlock_irqrestore(&gsm->control_lock, flags);
2042 wake_up(&gsm->event);
2043 return;
2044 }
2045 gsm->cretries--;
2046 gsm_control_transmit(gsm, ctrl);
2047 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
2048 }
2049 spin_unlock_irqrestore(&gsm->control_lock, flags);
2050}
2051
2052/**
2053 * gsm_control_send - send a control frame on DLCI 0
2054 * @gsm: the GSM channel
2055 * @command: command to send including CR bit
2056 * @data: bytes of data (must be kmalloced)
2057 * @clen: length of the block to send
2058 *
2059 * Queue and dispatch a control command. Only one command can be
2060 * active at a time. In theory more can be outstanding but the matching
2061 * gets really complicated so for now stick to one outstanding.
2062 */
2063
2064static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
2065 unsigned int command, u8 *data, int clen)
2066{
2067 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
2068 GFP_ATOMIC);
2069 unsigned long flags;
2070 if (ctrl == NULL)
2071 return NULL;
2072retry:
2073 wait_event(gsm->event, gsm->pending_cmd == NULL);
2074 spin_lock_irqsave(&gsm->control_lock, flags);
2075 if (gsm->pending_cmd != NULL) {
2076 spin_unlock_irqrestore(&gsm->control_lock, flags);
2077 goto retry;
2078 }
2079 ctrl->cmd = command;
2080 ctrl->data = data;
2081 ctrl->len = clen;
2082 gsm->pending_cmd = ctrl;
2083
2084 /* If DLCI0 is in ADM mode skip retries, it won't respond */
2085 if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
2086 gsm->cretries = 0;
2087 else
2088 gsm->cretries = gsm->n2;
2089
2090 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
2091 gsm_control_transmit(gsm, ctrl);
2092 spin_unlock_irqrestore(&gsm->control_lock, flags);
2093 return ctrl;
2094}
2095
2096/**
2097 * gsm_control_wait - wait for a control to finish
2098 * @gsm: GSM mux
2099 * @control: control we are waiting on
2100 *
2101 * Waits for the control to complete or time out. Frees any used
2102 * resources and returns 0 for success, or an error if the remote
2103 * rejected or ignored the request.
2104 */
2105
2106static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
2107{
2108 int err;
2109 wait_event(gsm->event, control->done == 1);
2110 err = control->error;
2111 kfree(control);
2112 return err;
2113}
2114
2115
2116/*
2117 * DLCI level handling: Needs krefs
2118 */
2119
2120/*
2121 * State transitions and timers
2122 */
2123
2124/**
2125 * gsm_dlci_close - a DLCI has closed
2126 * @dlci: DLCI that closed
2127 *
2128 * Perform processing when moving a DLCI into closed state. If there
2129 * is an attached tty this is hung up
2130 */
2131
2132static void gsm_dlci_close(struct gsm_dlci *dlci)
2133{
2134 del_timer(&dlci->t1);
2135 if (debug & DBG_ERRORS)
2136 pr_debug("DLCI %d goes closed.\n", dlci->addr);
2137 dlci->state = DLCI_CLOSED;
2138 /* Prevent us from sending data before the link is up again */
2139 dlci->constipated = true;
2140 if (dlci->addr != 0) {
2141 tty_port_tty_hangup(&dlci->port, false);
2142 gsm_dlci_clear_queues(dlci->gsm, dlci);
2143 /* Ensure that gsmtty_open() can return. */
2144 tty_port_set_initialized(&dlci->port, false);
2145 wake_up_interruptible(&dlci->port.open_wait);
2146 } else {
2147 del_timer(&dlci->gsm->ka_timer);
2148 dlci->gsm->dead = true;
2149 }
2150 /* A DLCI 0 close is a MUX termination so we need to kick that
2151 back to userspace somehow */
2152 gsm_dlci_data_kick(dlci);
2153 wake_up_all(&dlci->gsm->event);
2154}
2155
2156/**
2157 * gsm_dlci_open - a DLCI has opened
2158 * @dlci: DLCI that opened
2159 *
2160 * Perform processing when moving a DLCI into open state.
2161 */
2162
2163static void gsm_dlci_open(struct gsm_dlci *dlci)
2164{
2165 struct gsm_mux *gsm = dlci->gsm;
2166
2167 /* Note that SABM UA .. SABM UA first UA lost can mean that we go
2168 open -> open */
2169 del_timer(&dlci->t1);
2170 /* This will let a tty open continue */
2171 dlci->state = DLCI_OPEN;
2172 dlci->constipated = false;
2173 if (debug & DBG_ERRORS)
2174 pr_debug("DLCI %d goes open.\n", dlci->addr);
2175 /* Send current modem state */
2176 if (dlci->addr) {
2177 gsm_modem_update(dlci, 0);
2178 } else {
2179 /* Start keep-alive control */
2180 gsm->ka_num = 0;
2181 gsm->ka_retries = -1;
2182 mod_timer(&gsm->ka_timer,
2183 jiffies + gsm->keep_alive * HZ / 100);
2184 }
2185 gsm_dlci_data_kick(dlci);
2186 wake_up(&dlci->gsm->event);
2187}
2188
2189/**
2190 * gsm_dlci_negotiate - start parameter negotiation
2191 * @dlci: DLCI to open
2192 *
2193 * Starts the parameter negotiation for the new DLCI. This needs to be done
2194 * before the DLCI initialized the channel via SABM.
2195 */
2196static int gsm_dlci_negotiate(struct gsm_dlci *dlci)
2197{
2198 struct gsm_mux *gsm = dlci->gsm;
2199 struct gsm_dlci_param_bits params;
2200 int ret;
2201
2202 ret = gsm_encode_params(dlci, ¶ms);
2203 if (ret != 0)
2204 return ret;
2205
2206 /* We cannot asynchronous wait for the command response with
2207 * gsm_command() and gsm_control_wait() at this point.
2208 */
2209 ret = gsm_control_command(gsm, CMD_PN, (const u8 *)¶ms,
2210 sizeof(params));
2211
2212 return ret;
2213}
2214
2215/**
2216 * gsm_dlci_t1 - T1 timer expiry
2217 * @t: timer contained in the DLCI that opened
2218 *
2219 * The T1 timer handles retransmits of control frames (essentially of
2220 * SABM and DISC). We resend the command until the retry count runs out
2221 * in which case an opening port goes back to closed and a closing port
2222 * is simply put into closed state (any further frames from the other
2223 * end will get a DM response)
2224 *
2225 * Some control dlci can stay in ADM mode with other dlci working just
2226 * fine. In that case we can just keep the control dlci open after the
2227 * DLCI_OPENING retries time out.
2228 */
2229
2230static void gsm_dlci_t1(struct timer_list *t)
2231{
2232 struct gsm_dlci *dlci = from_timer(dlci, t, t1);
2233 struct gsm_mux *gsm = dlci->gsm;
2234
2235 switch (dlci->state) {
2236 case DLCI_CONFIGURE:
2237 if (dlci->retries && gsm_dlci_negotiate(dlci) == 0) {
2238 dlci->retries--;
2239 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2240 } else {
2241 gsm->open_error++;
2242 gsm_dlci_begin_close(dlci); /* prevent half open link */
2243 }
2244 break;
2245 case DLCI_OPENING:
2246 if (dlci->retries) {
2247 dlci->retries--;
2248 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
2249 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2250 } else if (!dlci->addr && gsm->control == (DM | PF)) {
2251 if (debug & DBG_ERRORS)
2252 pr_info("DLCI %d opening in ADM mode.\n",
2253 dlci->addr);
2254 dlci->mode = DLCI_MODE_ADM;
2255 gsm_dlci_open(dlci);
2256 } else {
2257 gsm->open_error++;
2258 gsm_dlci_begin_close(dlci); /* prevent half open link */
2259 }
2260
2261 break;
2262 case DLCI_CLOSING:
2263 if (dlci->retries) {
2264 dlci->retries--;
2265 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
2266 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2267 } else
2268 gsm_dlci_close(dlci);
2269 break;
2270 default:
2271 pr_debug("%s: unhandled state: %d\n", __func__, dlci->state);
2272 break;
2273 }
2274}
2275
2276/**
2277 * gsm_dlci_begin_open - start channel open procedure
2278 * @dlci: DLCI to open
2279 *
2280 * Commence opening a DLCI from the Linux side. We issue SABM messages
2281 * to the modem which should then reply with a UA or ADM, at which point
2282 * we will move into open state. Opening is done asynchronously with retry
2283 * running off timers and the responses.
2284 * Parameter negotiation is performed before SABM if required.
2285 */
2286
2287static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
2288{
2289 struct gsm_mux *gsm = dlci ? dlci->gsm : NULL;
2290 bool need_pn = false;
2291
2292 if (!gsm)
2293 return;
2294
2295 if (dlci->addr != 0) {
2296 if (gsm->adaption != 1 || gsm->adaption != dlci->adaption)
2297 need_pn = true;
2298 if (dlci->prio != (roundup(dlci->addr + 1, 8) - 1))
2299 need_pn = true;
2300 if (gsm->ftype != dlci->ftype)
2301 need_pn = true;
2302 }
2303
2304 switch (dlci->state) {
2305 case DLCI_CLOSED:
2306 case DLCI_WAITING_CONFIG:
2307 case DLCI_CLOSING:
2308 dlci->retries = gsm->n2;
2309 if (!need_pn) {
2310 dlci->state = DLCI_OPENING;
2311 gsm_command(gsm, dlci->addr, SABM|PF);
2312 } else {
2313 /* Configure DLCI before setup */
2314 dlci->state = DLCI_CONFIGURE;
2315 if (gsm_dlci_negotiate(dlci) != 0) {
2316 gsm_dlci_close(dlci);
2317 return;
2318 }
2319 }
2320 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2321 break;
2322 default:
2323 break;
2324 }
2325}
2326
2327/**
2328 * gsm_dlci_set_opening - change state to opening
2329 * @dlci: DLCI to open
2330 *
2331 * Change internal state to wait for DLCI open from initiator side.
2332 * We set off timers and responses upon reception of an SABM.
2333 */
2334static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
2335{
2336 switch (dlci->state) {
2337 case DLCI_CLOSED:
2338 case DLCI_WAITING_CONFIG:
2339 case DLCI_CLOSING:
2340 dlci->state = DLCI_OPENING;
2341 break;
2342 default:
2343 break;
2344 }
2345}
2346
2347/**
2348 * gsm_dlci_set_wait_config - wait for channel configuration
2349 * @dlci: DLCI to configure
2350 *
2351 * Wait for a DLCI configuration from the application.
2352 */
2353static void gsm_dlci_set_wait_config(struct gsm_dlci *dlci)
2354{
2355 switch (dlci->state) {
2356 case DLCI_CLOSED:
2357 case DLCI_CLOSING:
2358 dlci->state = DLCI_WAITING_CONFIG;
2359 break;
2360 default:
2361 break;
2362 }
2363}
2364
2365/**
2366 * gsm_dlci_begin_close - start channel open procedure
2367 * @dlci: DLCI to open
2368 *
2369 * Commence closing a DLCI from the Linux side. We issue DISC messages
2370 * to the modem which should then reply with a UA, at which point we
2371 * will move into closed state. Closing is done asynchronously with retry
2372 * off timers. We may also receive a DM reply from the other end which
2373 * indicates the channel was already closed.
2374 */
2375
2376static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
2377{
2378 struct gsm_mux *gsm = dlci->gsm;
2379 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
2380 return;
2381 dlci->retries = gsm->n2;
2382 dlci->state = DLCI_CLOSING;
2383 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
2384 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2385 wake_up_interruptible(&gsm->event);
2386}
2387
2388/**
2389 * gsm_dlci_data - data arrived
2390 * @dlci: channel
2391 * @data: block of bytes received
2392 * @clen: length of received block
2393 *
2394 * A UI or UIH frame has arrived which contains data for a channel
2395 * other than the control channel. If the relevant virtual tty is
2396 * open we shovel the bits down it, if not we drop them.
2397 */
2398
2399static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
2400{
2401 /* krefs .. */
2402 struct tty_port *port = &dlci->port;
2403 struct tty_struct *tty;
2404 unsigned int modem = 0;
2405 int len;
2406
2407 if (debug & DBG_TTY)
2408 pr_debug("%d bytes for tty\n", clen);
2409 switch (dlci->adaption) {
2410 /* Unsupported types */
2411 case 4: /* Packetised interruptible data */
2412 break;
2413 case 3: /* Packetised uininterruptible voice/data */
2414 break;
2415 case 2: /* Asynchronous serial with line state in each frame */
2416 len = gsm_read_ea_val(&modem, data, clen);
2417 if (len < 1)
2418 return;
2419 tty = tty_port_tty_get(port);
2420 if (tty) {
2421 gsm_process_modem(tty, dlci, modem, len);
2422 tty_wakeup(tty);
2423 tty_kref_put(tty);
2424 }
2425 /* Skip processed modem data */
2426 data += len;
2427 clen -= len;
2428 fallthrough;
2429 case 1: /* Line state will go via DLCI 0 controls only */
2430 default:
2431 tty_insert_flip_string(port, data, clen);
2432 tty_flip_buffer_push(port);
2433 }
2434}
2435
2436/**
2437 * gsm_dlci_command - data arrived on control channel
2438 * @dlci: channel
2439 * @data: block of bytes received
2440 * @len: length of received block
2441 *
2442 * A UI or UIH frame has arrived which contains data for DLCI 0 the
2443 * control channel. This should contain a command EA followed by
2444 * control data bytes. The command EA contains a command/response bit
2445 * and we divide up the work accordingly.
2446 */
2447
2448static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
2449{
2450 /* See what command is involved */
2451 unsigned int command = 0;
2452 unsigned int clen = 0;
2453 unsigned int dlen;
2454
2455 /* read the command */
2456 dlen = gsm_read_ea_val(&command, data, len);
2457 len -= dlen;
2458 data += dlen;
2459
2460 /* read any control data */
2461 dlen = gsm_read_ea_val(&clen, data, len);
2462 len -= dlen;
2463 data += dlen;
2464
2465 /* Malformed command? */
2466 if (clen > len) {
2467 dlci->gsm->malformed++;
2468 return;
2469 }
2470
2471 if (command & 1)
2472 gsm_control_message(dlci->gsm, command, data, clen);
2473 else
2474 gsm_control_response(dlci->gsm, command, data, clen);
2475}
2476
2477/**
2478 * gsm_kick_timer - transmit if possible
2479 * @t: timer contained in our gsm object
2480 *
2481 * Transmit data from DLCIs if the queue is empty. We can't rely on
2482 * a tty wakeup except when we filled the pipe so we need to fire off
2483 * new data ourselves in other cases.
2484 */
2485static void gsm_kick_timer(struct timer_list *t)
2486{
2487 struct gsm_mux *gsm = from_timer(gsm, t, kick_timer);
2488 unsigned long flags;
2489 int sent = 0;
2490
2491 spin_lock_irqsave(&gsm->tx_lock, flags);
2492 /* If we have nothing running then we need to fire up */
2493 if (gsm->tx_bytes < TX_THRESH_LO)
2494 sent = gsm_dlci_data_sweep(gsm);
2495 spin_unlock_irqrestore(&gsm->tx_lock, flags);
2496
2497 if (sent && debug & DBG_DATA)
2498 pr_info("%s TX queue stalled\n", __func__);
2499}
2500
2501/**
2502 * gsm_dlci_copy_config_values - copy DLCI configuration
2503 * @dlci: source DLCI
2504 * @dc: configuration structure to fill
2505 */
2506static void gsm_dlci_copy_config_values(struct gsm_dlci *dlci, struct gsm_dlci_config *dc)
2507{
2508 memset(dc, 0, sizeof(*dc));
2509 dc->channel = (u32)dlci->addr;
2510 dc->adaption = (u32)dlci->adaption;
2511 dc->mtu = (u32)dlci->mtu;
2512 dc->priority = (u32)dlci->prio;
2513 if (dlci->ftype == UIH)
2514 dc->i = 1;
2515 else
2516 dc->i = 2;
2517 dc->k = (u32)dlci->k;
2518}
2519
2520/**
2521 * gsm_dlci_config - configure DLCI from configuration
2522 * @dlci: DLCI to configure
2523 * @dc: DLCI configuration
2524 * @open: open DLCI after configuration?
2525 */
2526static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, int open)
2527{
2528 struct gsm_mux *gsm;
2529 bool need_restart = false;
2530 bool need_open = false;
2531 unsigned int i;
2532
2533 /*
2534 * Check that userspace doesn't put stuff in here to prevent breakages
2535 * in the future.
2536 */
2537 for (i = 0; i < ARRAY_SIZE(dc->reserved); i++)
2538 if (dc->reserved[i])
2539 return -EINVAL;
2540
2541 if (!dlci)
2542 return -EINVAL;
2543 gsm = dlci->gsm;
2544
2545 /* Stuff we don't support yet - I frame transport */
2546 if (dc->adaption != 1 && dc->adaption != 2)
2547 return -EOPNOTSUPP;
2548 if (dc->mtu > MAX_MTU || dc->mtu < MIN_MTU || dc->mtu > gsm->mru)
2549 return -EINVAL;
2550 if (dc->priority >= 64)
2551 return -EINVAL;
2552 if (dc->i == 0 || dc->i > 2) /* UIH and UI only */
2553 return -EINVAL;
2554 if (dc->k > 7)
2555 return -EINVAL;
2556 if (dc->flags & ~GSM_FL_RESTART) /* allow future extensions */
2557 return -EINVAL;
2558
2559 /*
2560 * See what is needed for reconfiguration
2561 */
2562 /* Framing fields */
2563 if (dc->adaption != dlci->adaption)
2564 need_restart = true;
2565 if (dc->mtu != dlci->mtu)
2566 need_restart = true;
2567 if (dc->i != dlci->ftype)
2568 need_restart = true;
2569 /* Requires care */
2570 if (dc->priority != dlci->prio)
2571 need_restart = true;
2572 if (dc->flags & GSM_FL_RESTART)
2573 need_restart = true;
2574
2575 if ((open && gsm->wait_config) || need_restart)
2576 need_open = true;
2577 if (dlci->state == DLCI_WAITING_CONFIG) {
2578 need_restart = false;
2579 need_open = true;
2580 }
2581
2582 /*
2583 * Close down what is needed, restart and initiate the new
2584 * configuration.
2585 */
2586 if (need_restart) {
2587 gsm_dlci_begin_close(dlci);
2588 wait_event_interruptible(gsm->event, dlci->state == DLCI_CLOSED);
2589 if (signal_pending(current))
2590 return -EINTR;
2591 }
2592 /*
2593 * Setup the new configuration values
2594 */
2595 dlci->adaption = (int)dc->adaption;
2596
2597 if (dc->mtu)
2598 dlci->mtu = (unsigned int)dc->mtu;
2599 else
2600 dlci->mtu = gsm->mtu;
2601
2602 if (dc->priority)
2603 dlci->prio = (u8)dc->priority;
2604 else
2605 dlci->prio = roundup(dlci->addr + 1, 8) - 1;
2606
2607 if (dc->i == 1)
2608 dlci->ftype = UIH;
2609 else if (dc->i == 2)
2610 dlci->ftype = UI;
2611
2612 if (dc->k)
2613 dlci->k = (u8)dc->k;
2614 else
2615 dlci->k = gsm->k;
2616
2617 if (need_open) {
2618 if (gsm->initiator)
2619 gsm_dlci_begin_open(dlci);
2620 else
2621 gsm_dlci_set_opening(dlci);
2622 }
2623
2624 return 0;
2625}
2626
2627/*
2628 * Allocate/Free DLCI channels
2629 */
2630
2631/**
2632 * gsm_dlci_alloc - allocate a DLCI
2633 * @gsm: GSM mux
2634 * @addr: address of the DLCI
2635 *
2636 * Allocate and install a new DLCI object into the GSM mux.
2637 *
2638 * FIXME: review locking races
2639 */
2640
2641static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
2642{
2643 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
2644 if (dlci == NULL)
2645 return NULL;
2646 spin_lock_init(&dlci->lock);
2647 mutex_init(&dlci->mutex);
2648 if (kfifo_alloc(&dlci->fifo, TX_SIZE, GFP_KERNEL) < 0) {
2649 kfree(dlci);
2650 return NULL;
2651 }
2652
2653 skb_queue_head_init(&dlci->skb_list);
2654 timer_setup(&dlci->t1, gsm_dlci_t1, 0);
2655 tty_port_init(&dlci->port);
2656 dlci->port.ops = &gsm_port_ops;
2657 dlci->gsm = gsm;
2658 dlci->addr = addr;
2659 dlci->adaption = gsm->adaption;
2660 dlci->mtu = gsm->mtu;
2661 if (addr == 0)
2662 dlci->prio = 0;
2663 else
2664 dlci->prio = roundup(addr + 1, 8) - 1;
2665 dlci->ftype = gsm->ftype;
2666 dlci->k = gsm->k;
2667 dlci->state = DLCI_CLOSED;
2668 if (addr) {
2669 dlci->data = gsm_dlci_data;
2670 /* Prevent us from sending data before the link is up */
2671 dlci->constipated = true;
2672 } else {
2673 dlci->data = gsm_dlci_command;
2674 }
2675 gsm->dlci[addr] = dlci;
2676 return dlci;
2677}
2678
2679/**
2680 * gsm_dlci_free - free DLCI
2681 * @port: tty port for DLCI to free
2682 *
2683 * Free up a DLCI.
2684 *
2685 * Can sleep.
2686 */
2687static void gsm_dlci_free(struct tty_port *port)
2688{
2689 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2690
2691 timer_shutdown_sync(&dlci->t1);
2692 dlci->gsm->dlci[dlci->addr] = NULL;
2693 kfifo_free(&dlci->fifo);
2694 while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
2695 dev_kfree_skb(dlci->skb);
2696 kfree(dlci);
2697}
2698
2699static inline void dlci_get(struct gsm_dlci *dlci)
2700{
2701 tty_port_get(&dlci->port);
2702}
2703
2704static inline void dlci_put(struct gsm_dlci *dlci)
2705{
2706 tty_port_put(&dlci->port);
2707}
2708
2709static void gsm_destroy_network(struct gsm_dlci *dlci);
2710
2711/**
2712 * gsm_dlci_release - release DLCI
2713 * @dlci: DLCI to destroy
2714 *
2715 * Release a DLCI. Actual free is deferred until either
2716 * mux is closed or tty is closed - whichever is last.
2717 *
2718 * Can sleep.
2719 */
2720static void gsm_dlci_release(struct gsm_dlci *dlci)
2721{
2722 struct tty_struct *tty = tty_port_tty_get(&dlci->port);
2723 if (tty) {
2724 mutex_lock(&dlci->mutex);
2725 gsm_destroy_network(dlci);
2726 mutex_unlock(&dlci->mutex);
2727
2728 /* We cannot use tty_hangup() because in tty_kref_put() the tty
2729 * driver assumes that the hangup queue is free and reuses it to
2730 * queue release_one_tty() -> NULL pointer panic in
2731 * process_one_work().
2732 */
2733 tty_vhangup(tty);
2734
2735 tty_port_tty_set(&dlci->port, NULL);
2736 tty_kref_put(tty);
2737 }
2738 dlci->state = DLCI_CLOSED;
2739 dlci_put(dlci);
2740}
2741
2742/*
2743 * LAPBish link layer logic
2744 */
2745
2746/**
2747 * gsm_queue - a GSM frame is ready to process
2748 * @gsm: pointer to our gsm mux
2749 *
2750 * At this point in time a frame has arrived and been demangled from
2751 * the line encoding. All the differences between the encodings have
2752 * been handled below us and the frame is unpacked into the structures.
2753 * The fcs holds the header FCS but any data FCS must be added here.
2754 */
2755
2756static void gsm_queue(struct gsm_mux *gsm)
2757{
2758 struct gsm_dlci *dlci;
2759 u8 cr;
2760 int address;
2761
2762 if (gsm->fcs != GOOD_FCS) {
2763 gsm->bad_fcs++;
2764 if (debug & DBG_DATA)
2765 pr_debug("BAD FCS %02x\n", gsm->fcs);
2766 return;
2767 }
2768 address = gsm->address >> 1;
2769 if (address >= NUM_DLCI)
2770 goto invalid;
2771
2772 cr = gsm->address & 1; /* C/R bit */
2773 cr ^= gsm->initiator ? 0 : 1; /* Flip so 1 always means command */
2774
2775 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
2776
2777 dlci = gsm->dlci[address];
2778
2779 switch (gsm->control) {
2780 case SABM|PF:
2781 if (cr == 1) {
2782 gsm->open_error++;
2783 goto invalid;
2784 }
2785 if (dlci == NULL)
2786 dlci = gsm_dlci_alloc(gsm, address);
2787 if (dlci == NULL) {
2788 gsm->open_error++;
2789 return;
2790 }
2791 if (dlci->dead)
2792 gsm_response(gsm, address, DM|PF);
2793 else {
2794 gsm_response(gsm, address, UA|PF);
2795 gsm_dlci_open(dlci);
2796 }
2797 break;
2798 case DISC|PF:
2799 if (cr == 1)
2800 goto invalid;
2801 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
2802 gsm_response(gsm, address, DM|PF);
2803 return;
2804 }
2805 /* Real close complete */
2806 gsm_response(gsm, address, UA|PF);
2807 gsm_dlci_close(dlci);
2808 break;
2809 case UA|PF:
2810 if (cr == 0 || dlci == NULL)
2811 break;
2812 switch (dlci->state) {
2813 case DLCI_CLOSING:
2814 gsm_dlci_close(dlci);
2815 break;
2816 case DLCI_OPENING:
2817 gsm_dlci_open(dlci);
2818 break;
2819 default:
2820 pr_debug("%s: unhandled state: %d\n", __func__,
2821 dlci->state);
2822 break;
2823 }
2824 break;
2825 case DM: /* DM can be valid unsolicited */
2826 case DM|PF:
2827 if (cr)
2828 goto invalid;
2829 if (dlci == NULL)
2830 return;
2831 gsm_dlci_close(dlci);
2832 break;
2833 case UI:
2834 case UI|PF:
2835 case UIH:
2836 case UIH|PF:
2837 if (dlci == NULL || dlci->state != DLCI_OPEN) {
2838 gsm_response(gsm, address, DM|PF);
2839 return;
2840 }
2841 dlci->data(dlci, gsm->buf, gsm->len);
2842 break;
2843 default:
2844 goto invalid;
2845 }
2846 return;
2847invalid:
2848 gsm->malformed++;
2849 return;
2850}
2851
2852/**
2853 * gsm0_receive_state_check_and_fix - check and correct receive state
2854 * @gsm: gsm data for this ldisc instance
2855 *
2856 * Ensures that the current receive state is valid for basic option mode.
2857 */
2858
2859static void gsm0_receive_state_check_and_fix(struct gsm_mux *gsm)
2860{
2861 switch (gsm->state) {
2862 case GSM_SEARCH:
2863 case GSM0_ADDRESS:
2864 case GSM0_CONTROL:
2865 case GSM0_LEN0:
2866 case GSM0_LEN1:
2867 case GSM0_DATA:
2868 case GSM0_FCS:
2869 case GSM0_SSOF:
2870 break;
2871 default:
2872 gsm->state = GSM_SEARCH;
2873 break;
2874 }
2875}
2876
2877/**
2878 * gsm0_receive - perform processing for non-transparency
2879 * @gsm: gsm data for this ldisc instance
2880 * @c: character
2881 *
2882 * Receive bytes in gsm mode 0
2883 */
2884
2885static void gsm0_receive(struct gsm_mux *gsm, u8 c)
2886{
2887 unsigned int len;
2888
2889 gsm0_receive_state_check_and_fix(gsm);
2890 switch (gsm->state) {
2891 case GSM_SEARCH: /* SOF marker */
2892 if (c == GSM0_SOF) {
2893 gsm->state = GSM0_ADDRESS;
2894 gsm->address = 0;
2895 gsm->len = 0;
2896 gsm->fcs = INIT_FCS;
2897 }
2898 break;
2899 case GSM0_ADDRESS: /* Address EA */
2900 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2901 if (gsm_read_ea(&gsm->address, c))
2902 gsm->state = GSM0_CONTROL;
2903 break;
2904 case GSM0_CONTROL: /* Control Byte */
2905 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2906 gsm->control = c;
2907 gsm->state = GSM0_LEN0;
2908 break;
2909 case GSM0_LEN0: /* Length EA */
2910 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2911 if (gsm_read_ea(&gsm->len, c)) {
2912 if (gsm->len > gsm->mru) {
2913 gsm->bad_size++;
2914 gsm->state = GSM_SEARCH;
2915 break;
2916 }
2917 gsm->count = 0;
2918 if (!gsm->len)
2919 gsm->state = GSM0_FCS;
2920 else
2921 gsm->state = GSM0_DATA;
2922 break;
2923 }
2924 gsm->state = GSM0_LEN1;
2925 break;
2926 case GSM0_LEN1:
2927 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2928 len = c;
2929 gsm->len |= len << 7;
2930 if (gsm->len > gsm->mru) {
2931 gsm->bad_size++;
2932 gsm->state = GSM_SEARCH;
2933 break;
2934 }
2935 gsm->count = 0;
2936 if (!gsm->len)
2937 gsm->state = GSM0_FCS;
2938 else
2939 gsm->state = GSM0_DATA;
2940 break;
2941 case GSM0_DATA: /* Data */
2942 gsm->buf[gsm->count++] = c;
2943 if (gsm->count >= MAX_MRU) {
2944 gsm->bad_size++;
2945 gsm->state = GSM_SEARCH;
2946 } else if (gsm->count >= gsm->len) {
2947 /* Calculate final FCS for UI frames over all data */
2948 if ((gsm->control & ~PF) != UIH) {
2949 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
2950 gsm->count);
2951 }
2952 gsm->state = GSM0_FCS;
2953 }
2954 break;
2955 case GSM0_FCS: /* FCS follows the packet */
2956 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2957 gsm->state = GSM0_SSOF;
2958 break;
2959 case GSM0_SSOF:
2960 gsm->state = GSM_SEARCH;
2961 if (c == GSM0_SOF)
2962 gsm_queue(gsm);
2963 else
2964 gsm->bad_size++;
2965 break;
2966 default:
2967 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2968 break;
2969 }
2970}
2971
2972/**
2973 * gsm1_receive_state_check_and_fix - check and correct receive state
2974 * @gsm: gsm data for this ldisc instance
2975 *
2976 * Ensures that the current receive state is valid for advanced option mode.
2977 */
2978
2979static void gsm1_receive_state_check_and_fix(struct gsm_mux *gsm)
2980{
2981 switch (gsm->state) {
2982 case GSM_SEARCH:
2983 case GSM1_START:
2984 case GSM1_ADDRESS:
2985 case GSM1_CONTROL:
2986 case GSM1_DATA:
2987 case GSM1_OVERRUN:
2988 break;
2989 default:
2990 gsm->state = GSM_SEARCH;
2991 break;
2992 }
2993}
2994
2995/**
2996 * gsm1_receive - perform processing for non-transparency
2997 * @gsm: gsm data for this ldisc instance
2998 * @c: character
2999 *
3000 * Receive bytes in mode 1 (Advanced option)
3001 */
3002
3003static void gsm1_receive(struct gsm_mux *gsm, u8 c)
3004{
3005 gsm1_receive_state_check_and_fix(gsm);
3006 /* handle XON/XOFF */
3007 if ((c & ISO_IEC_646_MASK) == XON) {
3008 gsm->constipated = true;
3009 return;
3010 } else if ((c & ISO_IEC_646_MASK) == XOFF) {
3011 gsm->constipated = false;
3012 /* Kick the link in case it is idling */
3013 gsmld_write_trigger(gsm);
3014 return;
3015 }
3016 if (c == GSM1_SOF) {
3017 /* EOF is only valid in frame if we have got to the data state */
3018 if (gsm->state == GSM1_DATA) {
3019 if (gsm->count < 1) {
3020 /* Missing FSC */
3021 gsm->malformed++;
3022 gsm->state = GSM1_START;
3023 return;
3024 }
3025 /* Remove the FCS from data */
3026 gsm->count--;
3027 if ((gsm->control & ~PF) != UIH) {
3028 /* Calculate final FCS for UI frames over all
3029 * data but FCS
3030 */
3031 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
3032 gsm->count);
3033 }
3034 /* Add the FCS itself to test against GOOD_FCS */
3035 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
3036 gsm->len = gsm->count;
3037 gsm_queue(gsm);
3038 gsm->state = GSM1_START;
3039 return;
3040 }
3041 /* Any partial frame was a runt so go back to start */
3042 if (gsm->state != GSM1_START) {
3043 if (gsm->state != GSM_SEARCH)
3044 gsm->malformed++;
3045 gsm->state = GSM1_START;
3046 }
3047 /* A SOF in GSM_START means we are still reading idling or
3048 framing bytes */
3049 return;
3050 }
3051
3052 if (c == GSM1_ESCAPE) {
3053 gsm->escape = true;
3054 return;
3055 }
3056
3057 /* Only an unescaped SOF gets us out of GSM search */
3058 if (gsm->state == GSM_SEARCH)
3059 return;
3060
3061 if (gsm->escape) {
3062 c ^= GSM1_ESCAPE_BITS;
3063 gsm->escape = false;
3064 }
3065 switch (gsm->state) {
3066 case GSM1_START: /* First byte after SOF */
3067 gsm->address = 0;
3068 gsm->state = GSM1_ADDRESS;
3069 gsm->fcs = INIT_FCS;
3070 fallthrough;
3071 case GSM1_ADDRESS: /* Address continuation */
3072 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
3073 if (gsm_read_ea(&gsm->address, c))
3074 gsm->state = GSM1_CONTROL;
3075 break;
3076 case GSM1_CONTROL: /* Control Byte */
3077 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
3078 gsm->control = c;
3079 gsm->count = 0;
3080 gsm->state = GSM1_DATA;
3081 break;
3082 case GSM1_DATA: /* Data */
3083 if (gsm->count > gsm->mru || gsm->count > MAX_MRU) { /* Allow one for the FCS */
3084 gsm->state = GSM1_OVERRUN;
3085 gsm->bad_size++;
3086 } else
3087 gsm->buf[gsm->count++] = c;
3088 break;
3089 case GSM1_OVERRUN: /* Over-long - eg a dropped SOF */
3090 break;
3091 default:
3092 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
3093 break;
3094 }
3095}
3096
3097/**
3098 * gsm_error - handle tty error
3099 * @gsm: ldisc data
3100 *
3101 * Handle an error in the receipt of data for a frame. Currently we just
3102 * go back to hunting for a SOF.
3103 *
3104 * FIXME: better diagnostics ?
3105 */
3106
3107static void gsm_error(struct gsm_mux *gsm)
3108{
3109 gsm->state = GSM_SEARCH;
3110 gsm->io_error++;
3111}
3112
3113/**
3114 * gsm_cleanup_mux - generic GSM protocol cleanup
3115 * @gsm: our mux
3116 * @disc: disconnect link?
3117 *
3118 * Clean up the bits of the mux which are the same for all framing
3119 * protocols. Remove the mux from the mux table, stop all the timers
3120 * and then shut down each device hanging up the channels as we go.
3121 */
3122
3123static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
3124{
3125 int i;
3126 struct gsm_dlci *dlci;
3127 struct gsm_msg *txq, *ntxq;
3128
3129 gsm->dead = true;
3130 mutex_lock(&gsm->mutex);
3131
3132 dlci = gsm->dlci[0];
3133 if (dlci) {
3134 if (disc && dlci->state != DLCI_CLOSED) {
3135 gsm_dlci_begin_close(dlci);
3136 wait_event(gsm->event, dlci->state == DLCI_CLOSED);
3137 }
3138 dlci->dead = true;
3139 }
3140
3141 /* Finish outstanding timers, making sure they are done */
3142 del_timer_sync(&gsm->kick_timer);
3143 del_timer_sync(&gsm->t2_timer);
3144 del_timer_sync(&gsm->ka_timer);
3145
3146 /* Finish writing to ldisc */
3147 flush_work(&gsm->tx_work);
3148
3149 /* Free up any link layer users and finally the control channel */
3150 if (gsm->has_devices) {
3151 gsm_unregister_devices(gsm_tty_driver, gsm->num);
3152 gsm->has_devices = false;
3153 }
3154 for (i = NUM_DLCI - 1; i >= 0; i--)
3155 if (gsm->dlci[i])
3156 gsm_dlci_release(gsm->dlci[i]);
3157 mutex_unlock(&gsm->mutex);
3158 /* Now wipe the queues */
3159 tty_ldisc_flush(gsm->tty);
3160
3161 guard(spinlock_irqsave)(&gsm->tx_lock);
3162 list_for_each_entry_safe(txq, ntxq, &gsm->tx_ctrl_list, list)
3163 kfree(txq);
3164 INIT_LIST_HEAD(&gsm->tx_ctrl_list);
3165 list_for_each_entry_safe(txq, ntxq, &gsm->tx_data_list, list)
3166 kfree(txq);
3167 INIT_LIST_HEAD(&gsm->tx_data_list);
3168}
3169
3170/**
3171 * gsm_activate_mux - generic GSM setup
3172 * @gsm: our mux
3173 *
3174 * Set up the bits of the mux which are the same for all framing
3175 * protocols. Add the mux to the mux table so it can be opened and
3176 * finally kick off connecting to DLCI 0 on the modem.
3177 */
3178
3179static int gsm_activate_mux(struct gsm_mux *gsm)
3180{
3181 struct gsm_dlci *dlci;
3182 int ret;
3183
3184 dlci = gsm_dlci_alloc(gsm, 0);
3185 if (dlci == NULL)
3186 return -ENOMEM;
3187
3188 if (gsm->encoding == GSM_BASIC_OPT)
3189 gsm->receive = gsm0_receive;
3190 else
3191 gsm->receive = gsm1_receive;
3192
3193 ret = gsm_register_devices(gsm_tty_driver, gsm->num);
3194 if (ret)
3195 return ret;
3196
3197 gsm->has_devices = true;
3198 gsm->dead = false; /* Tty opens are now permissible */
3199 return 0;
3200}
3201
3202/**
3203 * gsm_free_mux - free up a mux
3204 * @gsm: mux to free
3205 *
3206 * Dispose of allocated resources for a dead mux
3207 */
3208static void gsm_free_mux(struct gsm_mux *gsm)
3209{
3210 int i;
3211
3212 for (i = 0; i < MAX_MUX; i++) {
3213 if (gsm == gsm_mux[i]) {
3214 gsm_mux[i] = NULL;
3215 break;
3216 }
3217 }
3218 mutex_destroy(&gsm->mutex);
3219 kfree(gsm->txframe);
3220 kfree(gsm->buf);
3221 kfree(gsm);
3222}
3223
3224/**
3225 * gsm_free_muxr - free up a mux
3226 * @ref: kreference to the mux to free
3227 *
3228 * Dispose of allocated resources for a dead mux
3229 */
3230static void gsm_free_muxr(struct kref *ref)
3231{
3232 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
3233 gsm_free_mux(gsm);
3234}
3235
3236static inline void mux_get(struct gsm_mux *gsm)
3237{
3238 unsigned long flags;
3239
3240 spin_lock_irqsave(&gsm_mux_lock, flags);
3241 kref_get(&gsm->ref);
3242 spin_unlock_irqrestore(&gsm_mux_lock, flags);
3243}
3244
3245static inline void mux_put(struct gsm_mux *gsm)
3246{
3247 unsigned long flags;
3248
3249 spin_lock_irqsave(&gsm_mux_lock, flags);
3250 kref_put(&gsm->ref, gsm_free_muxr);
3251 spin_unlock_irqrestore(&gsm_mux_lock, flags);
3252}
3253
3254static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
3255{
3256 return gsm->num * NUM_DLCI;
3257}
3258
3259static inline unsigned int mux_line_to_num(unsigned int line)
3260{
3261 return line / NUM_DLCI;
3262}
3263
3264/**
3265 * gsm_alloc_mux - allocate a mux
3266 *
3267 * Creates a new mux ready for activation.
3268 */
3269
3270static struct gsm_mux *gsm_alloc_mux(void)
3271{
3272 int i;
3273 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
3274 if (gsm == NULL)
3275 return NULL;
3276 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
3277 if (gsm->buf == NULL) {
3278 kfree(gsm);
3279 return NULL;
3280 }
3281 gsm->txframe = kmalloc(2 * (MAX_MTU + PROT_OVERHEAD - 1), GFP_KERNEL);
3282 if (gsm->txframe == NULL) {
3283 kfree(gsm->buf);
3284 kfree(gsm);
3285 return NULL;
3286 }
3287 spin_lock_init(&gsm->lock);
3288 mutex_init(&gsm->mutex);
3289 kref_init(&gsm->ref);
3290 INIT_LIST_HEAD(&gsm->tx_ctrl_list);
3291 INIT_LIST_HEAD(&gsm->tx_data_list);
3292 timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
3293 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
3294 timer_setup(&gsm->ka_timer, gsm_control_keep_alive, 0);
3295 INIT_WORK(&gsm->tx_work, gsmld_write_task);
3296 init_waitqueue_head(&gsm->event);
3297 spin_lock_init(&gsm->control_lock);
3298 spin_lock_init(&gsm->tx_lock);
3299
3300 gsm->t1 = T1;
3301 gsm->t2 = T2;
3302 gsm->t3 = T3;
3303 gsm->n2 = N2;
3304 gsm->k = K;
3305 gsm->ftype = UIH;
3306 gsm->adaption = 1;
3307 gsm->encoding = GSM_ADV_OPT;
3308 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
3309 gsm->mtu = 64;
3310 gsm->dead = true; /* Avoid early tty opens */
3311 gsm->wait_config = false; /* Disabled */
3312 gsm->keep_alive = 0; /* Disabled */
3313
3314 /* Store the instance to the mux array or abort if no space is
3315 * available.
3316 */
3317 spin_lock(&gsm_mux_lock);
3318 for (i = 0; i < MAX_MUX; i++) {
3319 if (!gsm_mux[i]) {
3320 gsm_mux[i] = gsm;
3321 gsm->num = i;
3322 break;
3323 }
3324 }
3325 spin_unlock(&gsm_mux_lock);
3326 if (i == MAX_MUX) {
3327 mutex_destroy(&gsm->mutex);
3328 kfree(gsm->txframe);
3329 kfree(gsm->buf);
3330 kfree(gsm);
3331 return NULL;
3332 }
3333
3334 return gsm;
3335}
3336
3337static void gsm_copy_config_values(struct gsm_mux *gsm,
3338 struct gsm_config *c)
3339{
3340 memset(c, 0, sizeof(*c));
3341 c->adaption = gsm->adaption;
3342 c->encapsulation = gsm->encoding;
3343 c->initiator = gsm->initiator;
3344 c->t1 = gsm->t1;
3345 c->t2 = gsm->t2;
3346 c->t3 = gsm->t3;
3347 c->n2 = gsm->n2;
3348 if (gsm->ftype == UIH)
3349 c->i = 1;
3350 else
3351 c->i = 2;
3352 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
3353 c->mru = gsm->mru;
3354 c->mtu = gsm->mtu;
3355 c->k = gsm->k;
3356}
3357
3358static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
3359{
3360 int need_close = 0;
3361 int need_restart = 0;
3362
3363 /* Stuff we don't support yet - UI or I frame transport */
3364 if (c->adaption != 1 && c->adaption != 2)
3365 return -EOPNOTSUPP;
3366 /* Check the MRU/MTU range looks sane */
3367 if (c->mru < MIN_MTU || c->mtu < MIN_MTU)
3368 return -EINVAL;
3369 if (c->mru > MAX_MRU || c->mtu > MAX_MTU)
3370 return -EINVAL;
3371 if (c->t3 > MAX_T3)
3372 return -EINVAL;
3373 if (c->n2 > 255)
3374 return -EINVAL;
3375 if (c->encapsulation > 1) /* Basic, advanced, no I */
3376 return -EINVAL;
3377 if (c->initiator > 1)
3378 return -EINVAL;
3379 if (c->k > MAX_WINDOW_SIZE)
3380 return -EINVAL;
3381 if (c->i == 0 || c->i > 2) /* UIH and UI only */
3382 return -EINVAL;
3383 /*
3384 * See what is needed for reconfiguration
3385 */
3386
3387 /* Timing fields */
3388 if (c->t1 != 0 && c->t1 != gsm->t1)
3389 need_restart = 1;
3390 if (c->t2 != 0 && c->t2 != gsm->t2)
3391 need_restart = 1;
3392 if (c->encapsulation != gsm->encoding)
3393 need_restart = 1;
3394 if (c->adaption != gsm->adaption)
3395 need_restart = 1;
3396 /* Requires care */
3397 if (c->initiator != gsm->initiator)
3398 need_close = 1;
3399 if (c->mru != gsm->mru)
3400 need_restart = 1;
3401 if (c->mtu != gsm->mtu)
3402 need_restart = 1;
3403
3404 /*
3405 * Close down what is needed, restart and initiate the new
3406 * configuration. On the first time there is no DLCI[0]
3407 * and closing or cleaning up is not necessary.
3408 */
3409 if (need_close || need_restart)
3410 gsm_cleanup_mux(gsm, true);
3411
3412 gsm->initiator = c->initiator;
3413 gsm->mru = c->mru;
3414 gsm->mtu = c->mtu;
3415 gsm->encoding = c->encapsulation ? GSM_ADV_OPT : GSM_BASIC_OPT;
3416 gsm->adaption = c->adaption;
3417 gsm->n2 = c->n2;
3418
3419 if (c->i == 1)
3420 gsm->ftype = UIH;
3421 else if (c->i == 2)
3422 gsm->ftype = UI;
3423
3424 if (c->t1)
3425 gsm->t1 = c->t1;
3426 if (c->t2)
3427 gsm->t2 = c->t2;
3428 if (c->t3)
3429 gsm->t3 = c->t3;
3430 if (c->k)
3431 gsm->k = c->k;
3432
3433 /*
3434 * FIXME: We need to separate activation/deactivation from adding
3435 * and removing from the mux array
3436 */
3437 if (gsm->dead) {
3438 int ret = gsm_activate_mux(gsm);
3439 if (ret)
3440 return ret;
3441 if (gsm->initiator)
3442 gsm_dlci_begin_open(gsm->dlci[0]);
3443 }
3444 return 0;
3445}
3446
3447static void gsm_copy_config_ext_values(struct gsm_mux *gsm,
3448 struct gsm_config_ext *ce)
3449{
3450 memset(ce, 0, sizeof(*ce));
3451 ce->wait_config = gsm->wait_config ? 1 : 0;
3452 ce->keep_alive = gsm->keep_alive;
3453}
3454
3455static int gsm_config_ext(struct gsm_mux *gsm, struct gsm_config_ext *ce)
3456{
3457 bool need_restart = false;
3458 unsigned int i;
3459
3460 /*
3461 * Check that userspace doesn't put stuff in here to prevent breakages
3462 * in the future.
3463 */
3464 for (i = 0; i < ARRAY_SIZE(ce->reserved); i++)
3465 if (ce->reserved[i])
3466 return -EINVAL;
3467 if (ce->flags & ~GSM_FL_RESTART)
3468 return -EINVAL;
3469
3470 /* Requires care */
3471 if (ce->flags & GSM_FL_RESTART)
3472 need_restart = true;
3473
3474 /*
3475 * Close down what is needed, restart and initiate the new
3476 * configuration. On the first time there is no DLCI[0]
3477 * and closing or cleaning up is not necessary.
3478 */
3479 if (need_restart)
3480 gsm_cleanup_mux(gsm, true);
3481
3482 /*
3483 * Setup the new configuration values
3484 */
3485 gsm->wait_config = ce->wait_config ? true : false;
3486 gsm->keep_alive = ce->keep_alive;
3487
3488 if (gsm->dead) {
3489 int ret = gsm_activate_mux(gsm);
3490 if (ret)
3491 return ret;
3492 if (gsm->initiator)
3493 gsm_dlci_begin_open(gsm->dlci[0]);
3494 }
3495
3496 return 0;
3497}
3498
3499/**
3500 * gsmld_output - write to link
3501 * @gsm: our mux
3502 * @data: bytes to output
3503 * @len: size
3504 *
3505 * Write a block of data from the GSM mux to the data channel. This
3506 * will eventually be serialized from above but at the moment isn't.
3507 */
3508
3509static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
3510{
3511 if (tty_write_room(gsm->tty) < len) {
3512 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
3513 return -ENOSPC;
3514 }
3515 if (debug & DBG_DATA)
3516 gsm_hex_dump_bytes(__func__, data, len);
3517 return gsm->tty->ops->write(gsm->tty, data, len);
3518}
3519
3520
3521/**
3522 * gsmld_write_trigger - schedule ldisc write task
3523 * @gsm: our mux
3524 */
3525static void gsmld_write_trigger(struct gsm_mux *gsm)
3526{
3527 if (!gsm || !gsm->dlci[0] || gsm->dlci[0]->dead)
3528 return;
3529 schedule_work(&gsm->tx_work);
3530}
3531
3532
3533/**
3534 * gsmld_write_task - ldisc write task
3535 * @work: our tx write work
3536 *
3537 * Writes out data to the ldisc if possible. We are doing this here to
3538 * avoid dead-locking. This returns if no space or data is left for output.
3539 */
3540static void gsmld_write_task(struct work_struct *work)
3541{
3542 struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work);
3543 unsigned long flags;
3544 int i, ret;
3545
3546 /* All outstanding control channel and control messages and one data
3547 * frame is sent.
3548 */
3549 ret = -ENODEV;
3550 spin_lock_irqsave(&gsm->tx_lock, flags);
3551 if (gsm->tty)
3552 ret = gsm_data_kick(gsm);
3553 spin_unlock_irqrestore(&gsm->tx_lock, flags);
3554
3555 if (ret >= 0)
3556 for (i = 0; i < NUM_DLCI; i++)
3557 if (gsm->dlci[i])
3558 tty_port_tty_wakeup(&gsm->dlci[i]->port);
3559}
3560
3561/**
3562 * gsmld_attach_gsm - mode set up
3563 * @tty: our tty structure
3564 * @gsm: our mux
3565 *
3566 * Set up the MUX for basic mode and commence connecting to the
3567 * modem. Currently called from the line discipline set up but
3568 * will need moving to an ioctl path.
3569 */
3570
3571static void gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
3572{
3573 gsm->tty = tty_kref_get(tty);
3574 /* Turn off tty XON/XOFF handling to handle it explicitly. */
3575 gsm->old_c_iflag = tty->termios.c_iflag;
3576 tty->termios.c_iflag &= (IXON | IXOFF);
3577}
3578
3579/**
3580 * gsmld_detach_gsm - stop doing 0710 mux
3581 * @tty: tty attached to the mux
3582 * @gsm: mux
3583 *
3584 * Shutdown and then clean up the resources used by the line discipline
3585 */
3586
3587static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
3588{
3589 WARN_ON(tty != gsm->tty);
3590 /* Restore tty XON/XOFF handling. */
3591 gsm->tty->termios.c_iflag = gsm->old_c_iflag;
3592 tty_kref_put(gsm->tty);
3593 gsm->tty = NULL;
3594}
3595
3596static void gsmld_receive_buf(struct tty_struct *tty, const u8 *cp,
3597 const u8 *fp, size_t count)
3598{
3599 struct gsm_mux *gsm = tty->disc_data;
3600 u8 flags = TTY_NORMAL;
3601
3602 if (debug & DBG_DATA)
3603 gsm_hex_dump_bytes(__func__, cp, count);
3604
3605 for (; count; count--, cp++) {
3606 if (fp)
3607 flags = *fp++;
3608 switch (flags) {
3609 case TTY_NORMAL:
3610 if (gsm->receive)
3611 gsm->receive(gsm, *cp);
3612 break;
3613 case TTY_OVERRUN:
3614 case TTY_BREAK:
3615 case TTY_PARITY:
3616 case TTY_FRAME:
3617 gsm_error(gsm);
3618 break;
3619 default:
3620 WARN_ONCE(1, "%s: unknown flag %d\n",
3621 tty_name(tty), flags);
3622 break;
3623 }
3624 }
3625 /* FASYNC if needed ? */
3626 /* If clogged call tty_throttle(tty); */
3627}
3628
3629/**
3630 * gsmld_flush_buffer - clean input queue
3631 * @tty: terminal device
3632 *
3633 * Flush the input buffer. Called when the line discipline is
3634 * being closed, when the tty layer wants the buffer flushed (eg
3635 * at hangup).
3636 */
3637
3638static void gsmld_flush_buffer(struct tty_struct *tty)
3639{
3640}
3641
3642/**
3643 * gsmld_close - close the ldisc for this tty
3644 * @tty: device
3645 *
3646 * Called from the terminal layer when this line discipline is
3647 * being shut down, either because of a close or becsuse of a
3648 * discipline change. The function will not be called while other
3649 * ldisc methods are in progress.
3650 */
3651
3652static void gsmld_close(struct tty_struct *tty)
3653{
3654 struct gsm_mux *gsm = tty->disc_data;
3655
3656 /* The ldisc locks and closes the port before calling our close. This
3657 * means we have no way to do a proper disconnect. We will not bother
3658 * to do one.
3659 */
3660 gsm_cleanup_mux(gsm, false);
3661
3662 gsmld_detach_gsm(tty, gsm);
3663
3664 gsmld_flush_buffer(tty);
3665 /* Do other clean up here */
3666 mux_put(gsm);
3667}
3668
3669/**
3670 * gsmld_open - open an ldisc
3671 * @tty: terminal to open
3672 *
3673 * Called when this line discipline is being attached to the
3674 * terminal device. Can sleep. Called serialized so that no
3675 * other events will occur in parallel. No further open will occur
3676 * until a close.
3677 */
3678
3679static int gsmld_open(struct tty_struct *tty)
3680{
3681 struct gsm_mux *gsm;
3682
3683 if (!capable(CAP_NET_ADMIN))
3684 return -EPERM;
3685
3686 if (tty->ops->write == NULL)
3687 return -EINVAL;
3688
3689 /* Attach our ldisc data */
3690 gsm = gsm_alloc_mux();
3691 if (gsm == NULL)
3692 return -ENOMEM;
3693
3694 tty->disc_data = gsm;
3695 tty->receive_room = 65536;
3696
3697 /* Attach the initial passive connection */
3698 gsmld_attach_gsm(tty, gsm);
3699
3700 /* The mux will not be activated yet, we wait for correct
3701 * configuration first.
3702 */
3703 if (gsm->encoding == GSM_BASIC_OPT)
3704 gsm->receive = gsm0_receive;
3705 else
3706 gsm->receive = gsm1_receive;
3707
3708 return 0;
3709}
3710
3711/**
3712 * gsmld_write_wakeup - asynchronous I/O notifier
3713 * @tty: tty device
3714 *
3715 * Required for the ptys, serial driver etc. since processes
3716 * that attach themselves to the master and rely on ASYNC
3717 * IO must be woken up
3718 */
3719
3720static void gsmld_write_wakeup(struct tty_struct *tty)
3721{
3722 struct gsm_mux *gsm = tty->disc_data;
3723
3724 /* Queue poll */
3725 gsmld_write_trigger(gsm);
3726}
3727
3728/**
3729 * gsmld_read - read function for tty
3730 * @tty: tty device
3731 * @file: file object
3732 * @buf: userspace buffer pointer
3733 * @nr: size of I/O
3734 * @cookie: unused
3735 * @offset: unused
3736 *
3737 * Perform reads for the line discipline. We are guaranteed that the
3738 * line discipline will not be closed under us but we may get multiple
3739 * parallel readers and must handle this ourselves. We may also get
3740 * a hangup. Always called in user context, may sleep.
3741 *
3742 * This code must be sure never to sleep through a hangup.
3743 */
3744
3745static ssize_t gsmld_read(struct tty_struct *tty, struct file *file, u8 *buf,
3746 size_t nr, void **cookie, unsigned long offset)
3747{
3748 return -EOPNOTSUPP;
3749}
3750
3751/**
3752 * gsmld_write - write function for tty
3753 * @tty: tty device
3754 * @file: file object
3755 * @buf: userspace buffer pointer
3756 * @nr: size of I/O
3757 *
3758 * Called when the owner of the device wants to send a frame
3759 * itself (or some other control data). The data is transferred
3760 * as-is and must be properly framed and checksummed as appropriate
3761 * by userspace. Frames are either sent whole or not at all as this
3762 * avoids pain user side.
3763 */
3764
3765static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
3766 const u8 *buf, size_t nr)
3767{
3768 struct gsm_mux *gsm = tty->disc_data;
3769 unsigned long flags;
3770 size_t space;
3771 int ret;
3772
3773 if (!gsm)
3774 return -ENODEV;
3775
3776 ret = -ENOBUFS;
3777 spin_lock_irqsave(&gsm->tx_lock, flags);
3778 space = tty_write_room(tty);
3779 if (space >= nr)
3780 ret = tty->ops->write(tty, buf, nr);
3781 else
3782 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
3783 spin_unlock_irqrestore(&gsm->tx_lock, flags);
3784
3785 return ret;
3786}
3787
3788/**
3789 * gsmld_poll - poll method for N_GSM0710
3790 * @tty: terminal device
3791 * @file: file accessing it
3792 * @wait: poll table
3793 *
3794 * Called when the line discipline is asked to poll() for data or
3795 * for special events. This code is not serialized with respect to
3796 * other events save open/close.
3797 *
3798 * This code must be sure never to sleep through a hangup.
3799 * Called without the kernel lock held - fine
3800 */
3801
3802static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
3803 poll_table *wait)
3804{
3805 __poll_t mask = 0;
3806 struct gsm_mux *gsm = tty->disc_data;
3807
3808 poll_wait(file, &tty->read_wait, wait);
3809 poll_wait(file, &tty->write_wait, wait);
3810
3811 if (gsm->dead)
3812 mask |= EPOLLHUP;
3813 if (tty_hung_up_p(file))
3814 mask |= EPOLLHUP;
3815 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
3816 mask |= EPOLLHUP;
3817 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
3818 mask |= EPOLLOUT | EPOLLWRNORM;
3819 return mask;
3820}
3821
3822static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd,
3823 unsigned long arg)
3824{
3825 struct gsm_config c;
3826 struct gsm_config_ext ce;
3827 struct gsm_dlci_config dc;
3828 struct gsm_mux *gsm = tty->disc_data;
3829 unsigned int base, addr;
3830 struct gsm_dlci *dlci;
3831
3832 switch (cmd) {
3833 case GSMIOC_GETCONF:
3834 gsm_copy_config_values(gsm, &c);
3835 if (copy_to_user((void __user *)arg, &c, sizeof(c)))
3836 return -EFAULT;
3837 return 0;
3838 case GSMIOC_SETCONF:
3839 if (copy_from_user(&c, (void __user *)arg, sizeof(c)))
3840 return -EFAULT;
3841 return gsm_config(gsm, &c);
3842 case GSMIOC_GETFIRST:
3843 base = mux_num_to_base(gsm);
3844 return put_user(base + 1, (__u32 __user *)arg);
3845 case GSMIOC_GETCONF_EXT:
3846 gsm_copy_config_ext_values(gsm, &ce);
3847 if (copy_to_user((void __user *)arg, &ce, sizeof(ce)))
3848 return -EFAULT;
3849 return 0;
3850 case GSMIOC_SETCONF_EXT:
3851 if (copy_from_user(&ce, (void __user *)arg, sizeof(ce)))
3852 return -EFAULT;
3853 return gsm_config_ext(gsm, &ce);
3854 case GSMIOC_GETCONF_DLCI:
3855 if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
3856 return -EFAULT;
3857 if (dc.channel == 0 || dc.channel >= NUM_DLCI)
3858 return -EINVAL;
3859 addr = array_index_nospec(dc.channel, NUM_DLCI);
3860 dlci = gsm->dlci[addr];
3861 if (!dlci) {
3862 dlci = gsm_dlci_alloc(gsm, addr);
3863 if (!dlci)
3864 return -ENOMEM;
3865 }
3866 gsm_dlci_copy_config_values(dlci, &dc);
3867 if (copy_to_user((void __user *)arg, &dc, sizeof(dc)))
3868 return -EFAULT;
3869 return 0;
3870 case GSMIOC_SETCONF_DLCI:
3871 if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
3872 return -EFAULT;
3873 if (dc.channel == 0 || dc.channel >= NUM_DLCI)
3874 return -EINVAL;
3875 addr = array_index_nospec(dc.channel, NUM_DLCI);
3876 dlci = gsm->dlci[addr];
3877 if (!dlci) {
3878 dlci = gsm_dlci_alloc(gsm, addr);
3879 if (!dlci)
3880 return -ENOMEM;
3881 }
3882 return gsm_dlci_config(dlci, &dc, 0);
3883 default:
3884 return n_tty_ioctl_helper(tty, cmd, arg);
3885 }
3886}
3887
3888/*
3889 * Network interface
3890 *
3891 */
3892
3893static int gsm_mux_net_open(struct net_device *net)
3894{
3895 pr_debug("%s called\n", __func__);
3896 netif_start_queue(net);
3897 return 0;
3898}
3899
3900static int gsm_mux_net_close(struct net_device *net)
3901{
3902 netif_stop_queue(net);
3903 return 0;
3904}
3905
3906static void dlci_net_free(struct gsm_dlci *dlci)
3907{
3908 if (!dlci->net) {
3909 WARN_ON(1);
3910 return;
3911 }
3912 dlci->adaption = dlci->prev_adaption;
3913 dlci->data = dlci->prev_data;
3914 free_netdev(dlci->net);
3915 dlci->net = NULL;
3916}
3917static void net_free(struct kref *ref)
3918{
3919 struct gsm_mux_net *mux_net;
3920 struct gsm_dlci *dlci;
3921
3922 mux_net = container_of(ref, struct gsm_mux_net, ref);
3923 dlci = mux_net->dlci;
3924
3925 if (dlci->net) {
3926 unregister_netdev(dlci->net);
3927 dlci_net_free(dlci);
3928 }
3929}
3930
3931static inline void muxnet_get(struct gsm_mux_net *mux_net)
3932{
3933 kref_get(&mux_net->ref);
3934}
3935
3936static inline void muxnet_put(struct gsm_mux_net *mux_net)
3937{
3938 kref_put(&mux_net->ref, net_free);
3939}
3940
3941static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
3942 struct net_device *net)
3943{
3944 struct gsm_mux_net *mux_net = netdev_priv(net);
3945 struct gsm_dlci *dlci = mux_net->dlci;
3946 muxnet_get(mux_net);
3947
3948 skb_queue_head(&dlci->skb_list, skb);
3949 net->stats.tx_packets++;
3950 net->stats.tx_bytes += skb->len;
3951 gsm_dlci_data_kick(dlci);
3952 /* And tell the kernel when the last transmit started. */
3953 netif_trans_update(net);
3954 muxnet_put(mux_net);
3955 return NETDEV_TX_OK;
3956}
3957
3958/* called when a packet did not ack after watchdogtimeout */
3959static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue)
3960{
3961 /* Tell syslog we are hosed. */
3962 dev_dbg(&net->dev, "Tx timed out.\n");
3963
3964 /* Update statistics */
3965 net->stats.tx_errors++;
3966}
3967
3968static void gsm_mux_rx_netchar(struct gsm_dlci *dlci, const u8 *in_buf, int size)
3969{
3970 struct net_device *net = dlci->net;
3971 struct sk_buff *skb;
3972 struct gsm_mux_net *mux_net = netdev_priv(net);
3973 muxnet_get(mux_net);
3974
3975 /* Allocate an sk_buff */
3976 skb = dev_alloc_skb(size + NET_IP_ALIGN);
3977 if (!skb) {
3978 /* We got no receive buffer. */
3979 net->stats.rx_dropped++;
3980 muxnet_put(mux_net);
3981 return;
3982 }
3983 skb_reserve(skb, NET_IP_ALIGN);
3984 skb_put_data(skb, in_buf, size);
3985
3986 skb->dev = net;
3987 skb->protocol = htons(ETH_P_IP);
3988
3989 /* Ship it off to the kernel */
3990 netif_rx(skb);
3991
3992 /* update out statistics */
3993 net->stats.rx_packets++;
3994 net->stats.rx_bytes += size;
3995 muxnet_put(mux_net);
3996 return;
3997}
3998
3999static void gsm_mux_net_init(struct net_device *net)
4000{
4001 static const struct net_device_ops gsm_netdev_ops = {
4002 .ndo_open = gsm_mux_net_open,
4003 .ndo_stop = gsm_mux_net_close,
4004 .ndo_start_xmit = gsm_mux_net_start_xmit,
4005 .ndo_tx_timeout = gsm_mux_net_tx_timeout,
4006 };
4007
4008 net->netdev_ops = &gsm_netdev_ops;
4009
4010 /* fill in the other fields */
4011 net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
4012 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
4013 net->type = ARPHRD_NONE;
4014 net->tx_queue_len = 10;
4015}
4016
4017
4018/* caller holds the dlci mutex */
4019static void gsm_destroy_network(struct gsm_dlci *dlci)
4020{
4021 struct gsm_mux_net *mux_net;
4022
4023 pr_debug("destroy network interface\n");
4024 if (!dlci->net)
4025 return;
4026 mux_net = netdev_priv(dlci->net);
4027 muxnet_put(mux_net);
4028}
4029
4030
4031/* caller holds the dlci mutex */
4032static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
4033{
4034 char *netname;
4035 int retval = 0;
4036 struct net_device *net;
4037 struct gsm_mux_net *mux_net;
4038
4039 if (!capable(CAP_NET_ADMIN))
4040 return -EPERM;
4041
4042 /* Already in a non tty mode */
4043 if (dlci->adaption > 2)
4044 return -EBUSY;
4045
4046 if (nc->protocol != htons(ETH_P_IP))
4047 return -EPROTONOSUPPORT;
4048
4049 if (nc->adaption != 3 && nc->adaption != 4)
4050 return -EPROTONOSUPPORT;
4051
4052 pr_debug("create network interface\n");
4053
4054 netname = "gsm%d";
4055 if (nc->if_name[0] != '\0')
4056 netname = nc->if_name;
4057 net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
4058 NET_NAME_UNKNOWN, gsm_mux_net_init);
4059 if (!net) {
4060 pr_err("alloc_netdev failed\n");
4061 return -ENOMEM;
4062 }
4063 net->mtu = dlci->mtu;
4064 net->min_mtu = MIN_MTU;
4065 net->max_mtu = dlci->mtu;
4066 mux_net = netdev_priv(net);
4067 mux_net->dlci = dlci;
4068 kref_init(&mux_net->ref);
4069 strscpy(nc->if_name, net->name); /* return net name */
4070
4071 /* reconfigure dlci for network */
4072 dlci->prev_adaption = dlci->adaption;
4073 dlci->prev_data = dlci->data;
4074 dlci->adaption = nc->adaption;
4075 dlci->data = gsm_mux_rx_netchar;
4076 dlci->net = net;
4077
4078 pr_debug("register netdev\n");
4079 retval = register_netdev(net);
4080 if (retval) {
4081 pr_err("network register fail %d\n", retval);
4082 dlci_net_free(dlci);
4083 return retval;
4084 }
4085 return net->ifindex; /* return network index */
4086}
4087
4088/* Line discipline for real tty */
4089static struct tty_ldisc_ops tty_ldisc_packet = {
4090 .owner = THIS_MODULE,
4091 .num = N_GSM0710,
4092 .name = "n_gsm",
4093 .open = gsmld_open,
4094 .close = gsmld_close,
4095 .flush_buffer = gsmld_flush_buffer,
4096 .read = gsmld_read,
4097 .write = gsmld_write,
4098 .ioctl = gsmld_ioctl,
4099 .poll = gsmld_poll,
4100 .receive_buf = gsmld_receive_buf,
4101 .write_wakeup = gsmld_write_wakeup
4102};
4103
4104/*
4105 * Virtual tty side
4106 */
4107
4108/**
4109 * gsm_modem_upd_via_data - send modem bits via convergence layer
4110 * @dlci: channel
4111 * @brk: break signal
4112 *
4113 * Send an empty frame to signal mobile state changes and to transmit the
4114 * break signal for adaption 2.
4115 */
4116
4117static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk)
4118{
4119 struct gsm_mux *gsm = dlci->gsm;
4120 unsigned long flags;
4121
4122 if (dlci->state != DLCI_OPEN || dlci->adaption != 2)
4123 return;
4124
4125 spin_lock_irqsave(&gsm->tx_lock, flags);
4126 gsm_dlci_modem_output(gsm, dlci, brk);
4127 spin_unlock_irqrestore(&gsm->tx_lock, flags);
4128}
4129
4130/**
4131 * gsm_modem_upd_via_msc - send modem bits via control frame
4132 * @dlci: channel
4133 * @brk: break signal
4134 */
4135
4136static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk)
4137{
4138 u8 modembits[3];
4139 struct gsm_control *ctrl;
4140 int len = 2;
4141
4142 if (dlci->gsm->encoding != GSM_BASIC_OPT)
4143 return 0;
4144
4145 modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */
4146 if (!brk) {
4147 modembits[1] = (gsm_encode_modem(dlci) << 1) | EA;
4148 } else {
4149 modembits[1] = gsm_encode_modem(dlci) << 1;
4150 modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */
4151 len++;
4152 }
4153 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len);
4154 if (ctrl == NULL)
4155 return -ENOMEM;
4156 return gsm_control_wait(dlci->gsm, ctrl);
4157}
4158
4159/**
4160 * gsm_modem_update - send modem status line state
4161 * @dlci: channel
4162 * @brk: break signal
4163 */
4164
4165static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
4166{
4167 if (dlci->gsm->dead)
4168 return -EL2HLT;
4169 if (dlci->adaption == 2) {
4170 /* Send convergence layer type 2 empty data frame. */
4171 gsm_modem_upd_via_data(dlci, brk);
4172 return 0;
4173 } else if (dlci->gsm->encoding == GSM_BASIC_OPT) {
4174 /* Send as MSC control message. */
4175 return gsm_modem_upd_via_msc(dlci, brk);
4176 }
4177
4178 /* Modem status lines are not supported. */
4179 return -EPROTONOSUPPORT;
4180}
4181
4182/**
4183 * gsm_wait_modem_change - wait for modem status line change
4184 * @dlci: channel
4185 * @mask: modem status line bits
4186 *
4187 * The function returns if:
4188 * - any given modem status line bit changed
4189 * - the wait event function got interrupted (e.g. by a signal)
4190 * - the underlying DLCI was closed
4191 * - the underlying ldisc device was removed
4192 */
4193static int gsm_wait_modem_change(struct gsm_dlci *dlci, u32 mask)
4194{
4195 struct gsm_mux *gsm = dlci->gsm;
4196 u32 old = dlci->modem_rx;
4197 int ret;
4198
4199 ret = wait_event_interruptible(gsm->event, gsm->dead ||
4200 dlci->state != DLCI_OPEN ||
4201 (old ^ dlci->modem_rx) & mask);
4202 if (gsm->dead)
4203 return -ENODEV;
4204 if (dlci->state != DLCI_OPEN)
4205 return -EL2NSYNC;
4206 return ret;
4207}
4208
4209static bool gsm_carrier_raised(struct tty_port *port)
4210{
4211 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
4212 struct gsm_mux *gsm = dlci->gsm;
4213
4214 /* Not yet open so no carrier info */
4215 if (dlci->state != DLCI_OPEN)
4216 return false;
4217 if (debug & DBG_CD_ON)
4218 return true;
4219
4220 /*
4221 * Basic mode with control channel in ADM mode may not respond
4222 * to CMD_MSC at all and modem_rx is empty.
4223 */
4224 if (gsm->encoding == GSM_BASIC_OPT &&
4225 gsm->dlci[0]->mode == DLCI_MODE_ADM && !dlci->modem_rx)
4226 return true;
4227
4228 return dlci->modem_rx & TIOCM_CD;
4229}
4230
4231static void gsm_dtr_rts(struct tty_port *port, bool active)
4232{
4233 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
4234 unsigned int modem_tx = dlci->modem_tx;
4235 if (active)
4236 modem_tx |= TIOCM_DTR | TIOCM_RTS;
4237 else
4238 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
4239 if (modem_tx != dlci->modem_tx) {
4240 dlci->modem_tx = modem_tx;
4241 gsm_modem_update(dlci, 0);
4242 }
4243}
4244
4245static const struct tty_port_operations gsm_port_ops = {
4246 .carrier_raised = gsm_carrier_raised,
4247 .dtr_rts = gsm_dtr_rts,
4248 .destruct = gsm_dlci_free,
4249};
4250
4251static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
4252{
4253 struct gsm_mux *gsm;
4254 struct gsm_dlci *dlci;
4255 unsigned int line = tty->index;
4256 unsigned int mux = mux_line_to_num(line);
4257 bool alloc = false;
4258 int ret;
4259
4260 line = line & 0x3F;
4261
4262 if (mux >= MAX_MUX)
4263 return -ENXIO;
4264 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
4265 if (gsm_mux[mux] == NULL)
4266 return -EUNATCH;
4267 if (line == 0 || line > 61) /* 62/63 reserved */
4268 return -ECHRNG;
4269 gsm = gsm_mux[mux];
4270 if (gsm->dead)
4271 return -EL2HLT;
4272 /* If DLCI 0 is not yet fully open return an error.
4273 This is ok from a locking
4274 perspective as we don't have to worry about this
4275 if DLCI0 is lost */
4276 mutex_lock(&gsm->mutex);
4277 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
4278 mutex_unlock(&gsm->mutex);
4279 return -EL2NSYNC;
4280 }
4281 dlci = gsm->dlci[line];
4282 if (dlci == NULL) {
4283 alloc = true;
4284 dlci = gsm_dlci_alloc(gsm, line);
4285 }
4286 if (dlci == NULL) {
4287 mutex_unlock(&gsm->mutex);
4288 return -ENOMEM;
4289 }
4290 ret = tty_port_install(&dlci->port, driver, tty);
4291 if (ret) {
4292 if (alloc)
4293 dlci_put(dlci);
4294 mutex_unlock(&gsm->mutex);
4295 return ret;
4296 }
4297
4298 dlci_get(dlci);
4299 dlci_get(gsm->dlci[0]);
4300 mux_get(gsm);
4301 tty->driver_data = dlci;
4302 mutex_unlock(&gsm->mutex);
4303
4304 return 0;
4305}
4306
4307static int gsmtty_open(struct tty_struct *tty, struct file *filp)
4308{
4309 struct gsm_dlci *dlci = tty->driver_data;
4310 struct tty_port *port = &dlci->port;
4311
4312 port->count++;
4313 tty_port_tty_set(port, tty);
4314
4315 dlci->modem_rx = 0;
4316 /* We could in theory open and close before we wait - eg if we get
4317 a DM straight back. This is ok as that will have caused a hangup */
4318 tty_port_set_initialized(port, true);
4319 /* Start sending off SABM messages */
4320 if (!dlci->gsm->wait_config) {
4321 /* Start sending off SABM messages */
4322 if (dlci->gsm->initiator)
4323 gsm_dlci_begin_open(dlci);
4324 else
4325 gsm_dlci_set_opening(dlci);
4326 } else {
4327 gsm_dlci_set_wait_config(dlci);
4328 }
4329 /* And wait for virtual carrier */
4330 return tty_port_block_til_ready(port, tty, filp);
4331}
4332
4333static void gsmtty_close(struct tty_struct *tty, struct file *filp)
4334{
4335 struct gsm_dlci *dlci = tty->driver_data;
4336
4337 if (dlci == NULL)
4338 return;
4339 if (dlci->state == DLCI_CLOSED)
4340 return;
4341 mutex_lock(&dlci->mutex);
4342 gsm_destroy_network(dlci);
4343 mutex_unlock(&dlci->mutex);
4344 if (tty_port_close_start(&dlci->port, tty, filp) == 0)
4345 return;
4346 gsm_dlci_begin_close(dlci);
4347 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
4348 tty_port_lower_dtr_rts(&dlci->port);
4349 tty_port_close_end(&dlci->port, tty);
4350 tty_port_tty_set(&dlci->port, NULL);
4351 return;
4352}
4353
4354static void gsmtty_hangup(struct tty_struct *tty)
4355{
4356 struct gsm_dlci *dlci = tty->driver_data;
4357 if (dlci->state == DLCI_CLOSED)
4358 return;
4359 tty_port_hangup(&dlci->port);
4360 gsm_dlci_begin_close(dlci);
4361}
4362
4363static ssize_t gsmtty_write(struct tty_struct *tty, const u8 *buf, size_t len)
4364{
4365 int sent;
4366 struct gsm_dlci *dlci = tty->driver_data;
4367 if (dlci->state == DLCI_CLOSED)
4368 return -EINVAL;
4369 /* Stuff the bytes into the fifo queue */
4370 sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock);
4371 /* Need to kick the channel */
4372 gsm_dlci_data_kick(dlci);
4373 return sent;
4374}
4375
4376static unsigned int gsmtty_write_room(struct tty_struct *tty)
4377{
4378 struct gsm_dlci *dlci = tty->driver_data;
4379 if (dlci->state == DLCI_CLOSED)
4380 return 0;
4381 return kfifo_avail(&dlci->fifo);
4382}
4383
4384static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty)
4385{
4386 struct gsm_dlci *dlci = tty->driver_data;
4387 if (dlci->state == DLCI_CLOSED)
4388 return 0;
4389 return kfifo_len(&dlci->fifo);
4390}
4391
4392static void gsmtty_flush_buffer(struct tty_struct *tty)
4393{
4394 struct gsm_dlci *dlci = tty->driver_data;
4395 unsigned long flags;
4396
4397 if (dlci->state == DLCI_CLOSED)
4398 return;
4399 /* Caution needed: If we implement reliable transport classes
4400 then the data being transmitted can't simply be junked once
4401 it has first hit the stack. Until then we can just blow it
4402 away */
4403 spin_lock_irqsave(&dlci->lock, flags);
4404 kfifo_reset(&dlci->fifo);
4405 spin_unlock_irqrestore(&dlci->lock, flags);
4406 /* Need to unhook this DLCI from the transmit queue logic */
4407}
4408
4409static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
4410{
4411 /* The FIFO handles the queue so the kernel will do the right
4412 thing waiting on chars_in_buffer before calling us. No work
4413 to do here */
4414}
4415
4416static int gsmtty_tiocmget(struct tty_struct *tty)
4417{
4418 struct gsm_dlci *dlci = tty->driver_data;
4419 if (dlci->state == DLCI_CLOSED)
4420 return -EINVAL;
4421 return dlci->modem_rx;
4422}
4423
4424static int gsmtty_tiocmset(struct tty_struct *tty,
4425 unsigned int set, unsigned int clear)
4426{
4427 struct gsm_dlci *dlci = tty->driver_data;
4428 unsigned int modem_tx = dlci->modem_tx;
4429
4430 if (dlci->state == DLCI_CLOSED)
4431 return -EINVAL;
4432 modem_tx &= ~clear;
4433 modem_tx |= set;
4434
4435 if (modem_tx != dlci->modem_tx) {
4436 dlci->modem_tx = modem_tx;
4437 return gsm_modem_update(dlci, 0);
4438 }
4439 return 0;
4440}
4441
4442
4443static int gsmtty_ioctl(struct tty_struct *tty,
4444 unsigned int cmd, unsigned long arg)
4445{
4446 struct gsm_dlci *dlci = tty->driver_data;
4447 struct gsm_netconfig nc;
4448 struct gsm_dlci_config dc;
4449 int index;
4450
4451 if (dlci->state == DLCI_CLOSED)
4452 return -EINVAL;
4453 switch (cmd) {
4454 case GSMIOC_ENABLE_NET:
4455 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
4456 return -EFAULT;
4457 nc.if_name[IFNAMSIZ-1] = '\0';
4458 /* return net interface index or error code */
4459 mutex_lock(&dlci->mutex);
4460 index = gsm_create_network(dlci, &nc);
4461 mutex_unlock(&dlci->mutex);
4462 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
4463 return -EFAULT;
4464 return index;
4465 case GSMIOC_DISABLE_NET:
4466 if (!capable(CAP_NET_ADMIN))
4467 return -EPERM;
4468 mutex_lock(&dlci->mutex);
4469 gsm_destroy_network(dlci);
4470 mutex_unlock(&dlci->mutex);
4471 return 0;
4472 case GSMIOC_GETCONF_DLCI:
4473 if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
4474 return -EFAULT;
4475 if (dc.channel != dlci->addr)
4476 return -EPERM;
4477 gsm_dlci_copy_config_values(dlci, &dc);
4478 if (copy_to_user((void __user *)arg, &dc, sizeof(dc)))
4479 return -EFAULT;
4480 return 0;
4481 case GSMIOC_SETCONF_DLCI:
4482 if (copy_from_user(&dc, (void __user *)arg, sizeof(dc)))
4483 return -EFAULT;
4484 if (dc.channel >= NUM_DLCI)
4485 return -EINVAL;
4486 if (dc.channel != 0 && dc.channel != dlci->addr)
4487 return -EPERM;
4488 return gsm_dlci_config(dlci, &dc, 1);
4489 case TIOCMIWAIT:
4490 return gsm_wait_modem_change(dlci, (u32)arg);
4491 default:
4492 return -ENOIOCTLCMD;
4493 }
4494}
4495
4496static void gsmtty_set_termios(struct tty_struct *tty,
4497 const struct ktermios *old)
4498{
4499 struct gsm_dlci *dlci = tty->driver_data;
4500 if (dlci->state == DLCI_CLOSED)
4501 return;
4502 /* For the moment its fixed. In actual fact the speed information
4503 for the virtual channel can be propogated in both directions by
4504 the RPN control message. This however rapidly gets nasty as we
4505 then have to remap modem signals each way according to whether
4506 our virtual cable is null modem etc .. */
4507 tty_termios_copy_hw(&tty->termios, old);
4508}
4509
4510static void gsmtty_throttle(struct tty_struct *tty)
4511{
4512 struct gsm_dlci *dlci = tty->driver_data;
4513 if (dlci->state == DLCI_CLOSED)
4514 return;
4515 if (C_CRTSCTS(tty))
4516 dlci->modem_tx &= ~TIOCM_RTS;
4517 dlci->throttled = true;
4518 /* Send an MSC with RTS cleared */
4519 gsm_modem_update(dlci, 0);
4520}
4521
4522static void gsmtty_unthrottle(struct tty_struct *tty)
4523{
4524 struct gsm_dlci *dlci = tty->driver_data;
4525 if (dlci->state == DLCI_CLOSED)
4526 return;
4527 if (C_CRTSCTS(tty))
4528 dlci->modem_tx |= TIOCM_RTS;
4529 dlci->throttled = false;
4530 /* Send an MSC with RTS set */
4531 gsm_modem_update(dlci, 0);
4532}
4533
4534static int gsmtty_break_ctl(struct tty_struct *tty, int state)
4535{
4536 struct gsm_dlci *dlci = tty->driver_data;
4537 int encode = 0; /* Off */
4538 if (dlci->state == DLCI_CLOSED)
4539 return -EINVAL;
4540
4541 if (state == -1) /* "On indefinitely" - we can't encode this
4542 properly */
4543 encode = 0x0F;
4544 else if (state > 0) {
4545 encode = state / 200; /* mS to encoding */
4546 if (encode > 0x0F)
4547 encode = 0x0F; /* Best effort */
4548 }
4549 return gsm_modem_update(dlci, encode);
4550}
4551
4552static void gsmtty_cleanup(struct tty_struct *tty)
4553{
4554 struct gsm_dlci *dlci = tty->driver_data;
4555 struct gsm_mux *gsm = dlci->gsm;
4556
4557 dlci_put(dlci);
4558 dlci_put(gsm->dlci[0]);
4559 mux_put(gsm);
4560}
4561
4562/* Virtual ttys for the demux */
4563static const struct tty_operations gsmtty_ops = {
4564 .install = gsmtty_install,
4565 .open = gsmtty_open,
4566 .close = gsmtty_close,
4567 .write = gsmtty_write,
4568 .write_room = gsmtty_write_room,
4569 .chars_in_buffer = gsmtty_chars_in_buffer,
4570 .flush_buffer = gsmtty_flush_buffer,
4571 .ioctl = gsmtty_ioctl,
4572 .throttle = gsmtty_throttle,
4573 .unthrottle = gsmtty_unthrottle,
4574 .set_termios = gsmtty_set_termios,
4575 .hangup = gsmtty_hangup,
4576 .wait_until_sent = gsmtty_wait_until_sent,
4577 .tiocmget = gsmtty_tiocmget,
4578 .tiocmset = gsmtty_tiocmset,
4579 .break_ctl = gsmtty_break_ctl,
4580 .cleanup = gsmtty_cleanup,
4581};
4582
4583
4584
4585static int __init gsm_init(void)
4586{
4587 /* Fill in our line protocol discipline, and register it */
4588 int status = tty_register_ldisc(&tty_ldisc_packet);
4589 if (status != 0) {
4590 pr_err("n_gsm: can't register line discipline (err = %d)\n",
4591 status);
4592 return status;
4593 }
4594
4595 gsm_tty_driver = tty_alloc_driver(GSM_TTY_MINORS, TTY_DRIVER_REAL_RAW |
4596 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_HARDWARE_BREAK);
4597 if (IS_ERR(gsm_tty_driver)) {
4598 pr_err("gsm_init: tty allocation failed.\n");
4599 status = PTR_ERR(gsm_tty_driver);
4600 goto err_unreg_ldisc;
4601 }
4602 gsm_tty_driver->driver_name = "gsmtty";
4603 gsm_tty_driver->name = "gsmtty";
4604 gsm_tty_driver->major = 0; /* Dynamic */
4605 gsm_tty_driver->minor_start = 0;
4606 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
4607 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
4608 gsm_tty_driver->init_termios = tty_std_termios;
4609 /* Fixme */
4610 gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
4611 tty_set_operations(gsm_tty_driver, &gsmtty_ops);
4612
4613 if (tty_register_driver(gsm_tty_driver)) {
4614 pr_err("gsm_init: tty registration failed.\n");
4615 status = -EBUSY;
4616 goto err_put_driver;
4617 }
4618 pr_debug("gsm_init: loaded as %d,%d.\n",
4619 gsm_tty_driver->major, gsm_tty_driver->minor_start);
4620 return 0;
4621err_put_driver:
4622 tty_driver_kref_put(gsm_tty_driver);
4623err_unreg_ldisc:
4624 tty_unregister_ldisc(&tty_ldisc_packet);
4625 return status;
4626}
4627
4628static void __exit gsm_exit(void)
4629{
4630 tty_unregister_ldisc(&tty_ldisc_packet);
4631 tty_unregister_driver(gsm_tty_driver);
4632 tty_driver_kref_put(gsm_tty_driver);
4633}
4634
4635module_init(gsm_init);
4636module_exit(gsm_exit);
4637
4638
4639MODULE_DESCRIPTION("GSM 0710 tty multiplexor");
4640MODULE_LICENSE("GPL");
4641MODULE_ALIAS_LDISC(N_GSM0710);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * n_gsm.c GSM 0710 tty multiplexor
4 * Copyright (c) 2009/10 Intel Corporation
5 *
6 * * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
7 *
8 * Outgoing path:
9 * tty -> DLCI fifo -> scheduler -> GSM MUX data queue ---o-> ldisc
10 * control message -> GSM MUX control queue --ยด
11 *
12 * Incoming path:
13 * ldisc -> gsm_queue() -o--> tty
14 * `-> gsm_control_response()
15 *
16 * TO DO:
17 * Mostly done: ioctls for setting modes/timing
18 * Partly done: hooks so you can pull off frames to non tty devs
19 * Restart DLCI 0 when it closes ?
20 * Improve the tx engine
21 * Resolve tx side locking by adding a queue_head and routing
22 * all control traffic via it
23 * General tidy/document
24 * Review the locking/move to refcounts more (mux now moved to an
25 * alloc/free model ready)
26 * Use newest tty open/close port helpers and install hooks
27 * What to do about power functions ?
28 * Termios setting and negotiation
29 * Do we need a 'which mux are you' ioctl to correlate mux and tty sets
30 *
31 */
32
33#include <linux/types.h>
34#include <linux/major.h>
35#include <linux/errno.h>
36#include <linux/signal.h>
37#include <linux/fcntl.h>
38#include <linux/sched/signal.h>
39#include <linux/interrupt.h>
40#include <linux/tty.h>
41#include <linux/bitfield.h>
42#include <linux/ctype.h>
43#include <linux/mm.h>
44#include <linux/math.h>
45#include <linux/string.h>
46#include <linux/slab.h>
47#include <linux/poll.h>
48#include <linux/bitops.h>
49#include <linux/file.h>
50#include <linux/uaccess.h>
51#include <linux/module.h>
52#include <linux/timer.h>
53#include <linux/tty_flip.h>
54#include <linux/tty_driver.h>
55#include <linux/serial.h>
56#include <linux/kfifo.h>
57#include <linux/skbuff.h>
58#include <net/arp.h>
59#include <linux/ip.h>
60#include <linux/netdevice.h>
61#include <linux/etherdevice.h>
62#include <linux/gsmmux.h>
63#include "tty.h"
64
65static int debug;
66module_param(debug, int, 0600);
67
68/* Module debug bits */
69#define DBG_DUMP BIT(0) /* Data transmission dump. */
70#define DBG_CD_ON BIT(1) /* Always assume CD line on. */
71#define DBG_DATA BIT(2) /* Data transmission details. */
72#define DBG_ERRORS BIT(3) /* Details for fail conditions. */
73#define DBG_TTY BIT(4) /* Transmission statistics for DLCI TTYs. */
74#define DBG_PAYLOAD BIT(5) /* Limits DBG_DUMP to payload frames. */
75
76/* Defaults: these are from the specification */
77
78#define T1 10 /* 100mS */
79#define T2 34 /* 333mS */
80#define T3 10 /* 10s */
81#define N2 3 /* Retry 3 times */
82#define K 2 /* outstanding I frames */
83
84#define MAX_T3 255 /* In seconds. */
85#define MAX_WINDOW_SIZE 7 /* Limit of K in error recovery mode. */
86
87/* Use long timers for testing at low speed with debug on */
88#ifdef DEBUG_TIMING
89#define T1 100
90#define T2 200
91#endif
92
93/*
94 * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
95 * limits so this is plenty
96 */
97#define MAX_MRU 1500
98#define MAX_MTU 1500
99#define MIN_MTU (PROT_OVERHEAD + 1)
100/* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */
101#define PROT_OVERHEAD 7
102#define GSM_NET_TX_TIMEOUT (HZ*10)
103
104/*
105 * struct gsm_mux_net - network interface
106 *
107 * Created when net interface is initialized.
108 */
109struct gsm_mux_net {
110 struct kref ref;
111 struct gsm_dlci *dlci;
112};
113
114/*
115 * Each block of data we have queued to go out is in the form of
116 * a gsm_msg which holds everything we need in a link layer independent
117 * format
118 */
119
120struct gsm_msg {
121 struct list_head list;
122 u8 addr; /* DLCI address + flags */
123 u8 ctrl; /* Control byte + flags */
124 unsigned int len; /* Length of data block (can be zero) */
125 unsigned char *data; /* Points into buffer but not at the start */
126 unsigned char buffer[];
127};
128
129enum gsm_dlci_state {
130 DLCI_CLOSED,
131 DLCI_CONFIGURE, /* Sending PN (for adaption > 1) */
132 DLCI_OPENING, /* Sending SABM not seen UA */
133 DLCI_OPEN, /* SABM/UA complete */
134 DLCI_CLOSING, /* Sending DISC not seen UA/DM */
135};
136
137enum gsm_dlci_mode {
138 DLCI_MODE_ABM, /* Normal Asynchronous Balanced Mode */
139 DLCI_MODE_ADM, /* Asynchronous Disconnected Mode */
140};
141
142/*
143 * Each active data link has a gsm_dlci structure associated which ties
144 * the link layer to an optional tty (if the tty side is open). To avoid
145 * complexity right now these are only ever freed up when the mux is
146 * shut down.
147 *
148 * At the moment we don't free DLCI objects until the mux is torn down
149 * this avoid object life time issues but might be worth review later.
150 */
151
152struct gsm_dlci {
153 struct gsm_mux *gsm;
154 int addr;
155 enum gsm_dlci_state state;
156 struct mutex mutex;
157
158 /* Link layer */
159 enum gsm_dlci_mode mode;
160 spinlock_t lock; /* Protects the internal state */
161 struct timer_list t1; /* Retransmit timer for SABM and UA */
162 int retries;
163 /* Uplink tty if active */
164 struct tty_port port; /* The tty bound to this DLCI if there is one */
165#define TX_SIZE 4096 /* Must be power of 2. */
166 struct kfifo fifo; /* Queue fifo for the DLCI */
167 int adaption; /* Adaption layer in use */
168 int prev_adaption;
169 u32 modem_rx; /* Our incoming virtual modem lines */
170 u32 modem_tx; /* Our outgoing modem lines */
171 unsigned int mtu;
172 bool dead; /* Refuse re-open */
173 /* Configuration */
174 u8 prio; /* Priority */
175 u8 ftype; /* Frame type */
176 u8 k; /* Window size */
177 /* Flow control */
178 bool throttled; /* Private copy of throttle state */
179 bool constipated; /* Throttle status for outgoing */
180 /* Packetised I/O */
181 struct sk_buff *skb; /* Frame being sent */
182 struct sk_buff_head skb_list; /* Queued frames */
183 /* Data handling callback */
184 void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
185 void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
186 struct net_device *net; /* network interface, if created */
187};
188
189/*
190 * Parameter bits used for parameter negotiation according to 3GPP 27.010
191 * chapter 5.4.6.3.1.
192 */
193
194struct gsm_dlci_param_bits {
195 u8 d_bits;
196 u8 i_cl_bits;
197 u8 p_bits;
198 u8 t_bits;
199 __le16 n_bits;
200 u8 na_bits;
201 u8 k_bits;
202};
203
204static_assert(sizeof(struct gsm_dlci_param_bits) == 8);
205
206#define PN_D_FIELD_DLCI GENMASK(5, 0)
207#define PN_I_CL_FIELD_FTYPE GENMASK(3, 0)
208#define PN_I_CL_FIELD_ADAPTION GENMASK(7, 4)
209#define PN_P_FIELD_PRIO GENMASK(5, 0)
210#define PN_T_FIELD_T1 GENMASK(7, 0)
211#define PN_N_FIELD_N1 GENMASK(15, 0)
212#define PN_NA_FIELD_N2 GENMASK(7, 0)
213#define PN_K_FIELD_K GENMASK(2, 0)
214
215/* Total number of supported devices */
216#define GSM_TTY_MINORS 256
217
218/* DLCI 0, 62/63 are special or reserved see gsmtty_open */
219
220#define NUM_DLCI 64
221
222/*
223 * DLCI 0 is used to pass control blocks out of band of the data
224 * flow (and with a higher link priority). One command can be outstanding
225 * at a time and we use this structure to manage them. They are created
226 * and destroyed by the user context, and updated by the receive paths
227 * and timers
228 */
229
230struct gsm_control {
231 u8 cmd; /* Command we are issuing */
232 u8 *data; /* Data for the command in case we retransmit */
233 int len; /* Length of block for retransmission */
234 int done; /* Done flag */
235 int error; /* Error if any */
236};
237
238enum gsm_encoding {
239 GSM_BASIC_OPT,
240 GSM_ADV_OPT,
241};
242
243enum gsm_mux_state {
244 GSM_SEARCH,
245 GSM_START,
246 GSM_ADDRESS,
247 GSM_CONTROL,
248 GSM_LEN,
249 GSM_DATA,
250 GSM_FCS,
251 GSM_OVERRUN,
252 GSM_LEN0,
253 GSM_LEN1,
254 GSM_SSOF,
255};
256
257/*
258 * Each GSM mux we have is represented by this structure. If we are
259 * operating as an ldisc then we use this structure as our ldisc
260 * state. We need to sort out lifetimes and locking with respect
261 * to the gsm mux array. For now we don't free DLCI objects that
262 * have been instantiated until the mux itself is terminated.
263 *
264 * To consider further: tty open versus mux shutdown.
265 */
266
267struct gsm_mux {
268 struct tty_struct *tty; /* The tty our ldisc is bound to */
269 spinlock_t lock;
270 struct mutex mutex;
271 unsigned int num;
272 struct kref ref;
273
274 /* Events on the GSM channel */
275 wait_queue_head_t event;
276
277 /* ldisc send work */
278 struct work_struct tx_work;
279
280 /* Bits for GSM mode decoding */
281
282 /* Framing Layer */
283 unsigned char *buf;
284 enum gsm_mux_state state;
285 unsigned int len;
286 unsigned int address;
287 unsigned int count;
288 bool escape;
289 enum gsm_encoding encoding;
290 u8 control;
291 u8 fcs;
292 u8 *txframe; /* TX framing buffer */
293
294 /* Method for the receiver side */
295 void (*receive)(struct gsm_mux *gsm, u8 ch);
296
297 /* Link Layer */
298 unsigned int mru;
299 unsigned int mtu;
300 int initiator; /* Did we initiate connection */
301 bool dead; /* Has the mux been shut down */
302 struct gsm_dlci *dlci[NUM_DLCI];
303 int old_c_iflag; /* termios c_iflag value before attach */
304 bool constipated; /* Asked by remote to shut up */
305 bool has_devices; /* Devices were registered */
306
307 spinlock_t tx_lock;
308 unsigned int tx_bytes; /* TX data outstanding */
309#define TX_THRESH_HI 8192
310#define TX_THRESH_LO 2048
311 struct list_head tx_ctrl_list; /* Pending control packets */
312 struct list_head tx_data_list; /* Pending data packets */
313
314 /* Control messages */
315 struct timer_list kick_timer; /* Kick TX queuing on timeout */
316 struct timer_list t2_timer; /* Retransmit timer for commands */
317 int cretries; /* Command retry counter */
318 struct gsm_control *pending_cmd;/* Our current pending command */
319 spinlock_t control_lock; /* Protects the pending command */
320
321 /* Configuration */
322 int adaption; /* 1 or 2 supported */
323 u8 ftype; /* UI or UIH */
324 int t1, t2; /* Timers in 1/100th of a sec */
325 unsigned int t3; /* Power wake-up timer in seconds. */
326 int n2; /* Retry count */
327 u8 k; /* Window size */
328
329 /* Statistics (not currently exposed) */
330 unsigned long bad_fcs;
331 unsigned long malformed;
332 unsigned long io_error;
333 unsigned long bad_size;
334 unsigned long unsupported;
335};
336
337
338/*
339 * Mux objects - needed so that we can translate a tty index into the
340 * relevant mux and DLCI.
341 */
342
343#define MAX_MUX 4 /* 256 minors */
344static struct gsm_mux *gsm_mux[MAX_MUX]; /* GSM muxes */
345static DEFINE_SPINLOCK(gsm_mux_lock);
346
347static struct tty_driver *gsm_tty_driver;
348
349/*
350 * This section of the driver logic implements the GSM encodings
351 * both the basic and the 'advanced'. Reliable transport is not
352 * supported.
353 */
354
355#define CR 0x02
356#define EA 0x01
357#define PF 0x10
358
359/* I is special: the rest are ..*/
360#define RR 0x01
361#define UI 0x03
362#define RNR 0x05
363#define REJ 0x09
364#define DM 0x0F
365#define SABM 0x2F
366#define DISC 0x43
367#define UA 0x63
368#define UIH 0xEF
369
370/* Channel commands */
371#define CMD_NSC 0x09
372#define CMD_TEST 0x11
373#define CMD_PSC 0x21
374#define CMD_RLS 0x29
375#define CMD_FCOFF 0x31
376#define CMD_PN 0x41
377#define CMD_RPN 0x49
378#define CMD_FCON 0x51
379#define CMD_CLD 0x61
380#define CMD_SNC 0x69
381#define CMD_MSC 0x71
382
383/* Virtual modem bits */
384#define MDM_FC 0x01
385#define MDM_RTC 0x02
386#define MDM_RTR 0x04
387#define MDM_IC 0x20
388#define MDM_DV 0x40
389
390#define GSM0_SOF 0xF9
391#define GSM1_SOF 0x7E
392#define GSM1_ESCAPE 0x7D
393#define GSM1_ESCAPE_BITS 0x20
394#define XON 0x11
395#define XOFF 0x13
396#define ISO_IEC_646_MASK 0x7F
397
398static const struct tty_port_operations gsm_port_ops;
399
400/*
401 * CRC table for GSM 0710
402 */
403
404static const u8 gsm_fcs8[256] = {
405 0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
406 0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
407 0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
408 0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
409 0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
410 0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
411 0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
412 0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
413 0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
414 0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
415 0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
416 0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
417 0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
418 0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
419 0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
420 0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
421 0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
422 0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
423 0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
424 0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
425 0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
426 0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
427 0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
428 0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
429 0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
430 0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
431 0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
432 0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
433 0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
434 0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
435 0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
436 0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
437};
438
439#define INIT_FCS 0xFF
440#define GOOD_FCS 0xCF
441
442static void gsm_dlci_close(struct gsm_dlci *dlci);
443static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
444static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
445static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
446 u8 ctrl);
447static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg);
448static void gsmld_write_trigger(struct gsm_mux *gsm);
449static void gsmld_write_task(struct work_struct *work);
450
451/**
452 * gsm_fcs_add - update FCS
453 * @fcs: Current FCS
454 * @c: Next data
455 *
456 * Update the FCS to include c. Uses the algorithm in the specification
457 * notes.
458 */
459
460static inline u8 gsm_fcs_add(u8 fcs, u8 c)
461{
462 return gsm_fcs8[fcs ^ c];
463}
464
465/**
466 * gsm_fcs_add_block - update FCS for a block
467 * @fcs: Current FCS
468 * @c: buffer of data
469 * @len: length of buffer
470 *
471 * Update the FCS to include c. Uses the algorithm in the specification
472 * notes.
473 */
474
475static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
476{
477 while (len--)
478 fcs = gsm_fcs8[fcs ^ *c++];
479 return fcs;
480}
481
482/**
483 * gsm_read_ea - read a byte into an EA
484 * @val: variable holding value
485 * @c: byte going into the EA
486 *
487 * Processes one byte of an EA. Updates the passed variable
488 * and returns 1 if the EA is now completely read
489 */
490
491static int gsm_read_ea(unsigned int *val, u8 c)
492{
493 /* Add the next 7 bits into the value */
494 *val <<= 7;
495 *val |= c >> 1;
496 /* Was this the last byte of the EA 1 = yes*/
497 return c & EA;
498}
499
500/**
501 * gsm_read_ea_val - read a value until EA
502 * @val: variable holding value
503 * @data: buffer of data
504 * @dlen: length of data
505 *
506 * Processes an EA value. Updates the passed variable and
507 * returns the processed data length.
508 */
509static unsigned int gsm_read_ea_val(unsigned int *val, const u8 *data, int dlen)
510{
511 unsigned int len = 0;
512
513 for (; dlen > 0; dlen--) {
514 len++;
515 if (gsm_read_ea(val, *data++))
516 break;
517 }
518 return len;
519}
520
521/**
522 * gsm_encode_modem - encode modem data bits
523 * @dlci: DLCI to encode from
524 *
525 * Returns the correct GSM encoded modem status bits (6 bit field) for
526 * the current status of the DLCI and attached tty object
527 */
528
529static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
530{
531 u8 modembits = 0;
532 /* FC is true flow control not modem bits */
533 if (dlci->throttled)
534 modembits |= MDM_FC;
535 if (dlci->modem_tx & TIOCM_DTR)
536 modembits |= MDM_RTC;
537 if (dlci->modem_tx & TIOCM_RTS)
538 modembits |= MDM_RTR;
539 if (dlci->modem_tx & TIOCM_RI)
540 modembits |= MDM_IC;
541 if (dlci->modem_tx & TIOCM_CD || dlci->gsm->initiator)
542 modembits |= MDM_DV;
543 return modembits;
544}
545
546static void gsm_hex_dump_bytes(const char *fname, const u8 *data,
547 unsigned long len)
548{
549 char *prefix;
550
551 if (!fname) {
552 print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, data, len,
553 true);
554 return;
555 }
556
557 prefix = kasprintf(GFP_ATOMIC, "%s: ", fname);
558 if (!prefix)
559 return;
560 print_hex_dump(KERN_INFO, prefix, DUMP_PREFIX_OFFSET, 16, 1, data, len,
561 true);
562 kfree(prefix);
563}
564
565/**
566 * gsm_encode_params - encode DLCI parameters
567 * @dlci: DLCI to encode from
568 * @params: buffer to fill with the encoded parameters
569 *
570 * Encodes the parameters according to GSM 07.10 section 5.4.6.3.1
571 * table 3.
572 */
573static int gsm_encode_params(const struct gsm_dlci *dlci,
574 struct gsm_dlci_param_bits *params)
575{
576 const struct gsm_mux *gsm = dlci->gsm;
577 unsigned int i, cl;
578
579 switch (dlci->ftype) {
580 case UIH:
581 i = 0; /* UIH */
582 break;
583 case UI:
584 i = 1; /* UI */
585 break;
586 default:
587 pr_debug("unsupported frame type %d\n", dlci->ftype);
588 return -EINVAL;
589 }
590
591 switch (dlci->adaption) {
592 case 1: /* Unstructured */
593 cl = 0; /* convergence layer type 1 */
594 break;
595 case 2: /* Unstructured with modem bits. */
596 cl = 1; /* convergence layer type 2 */
597 break;
598 default:
599 pr_debug("unsupported adaption %d\n", dlci->adaption);
600 return -EINVAL;
601 }
602
603 params->d_bits = FIELD_PREP(PN_D_FIELD_DLCI, dlci->addr);
604 /* UIH, convergence layer type 1 */
605 params->i_cl_bits = FIELD_PREP(PN_I_CL_FIELD_FTYPE, i) |
606 FIELD_PREP(PN_I_CL_FIELD_ADAPTION, cl);
607 params->p_bits = FIELD_PREP(PN_P_FIELD_PRIO, dlci->prio);
608 params->t_bits = FIELD_PREP(PN_T_FIELD_T1, gsm->t1);
609 params->n_bits = cpu_to_le16(FIELD_PREP(PN_N_FIELD_N1, dlci->mtu));
610 params->na_bits = FIELD_PREP(PN_NA_FIELD_N2, gsm->n2);
611 params->k_bits = FIELD_PREP(PN_K_FIELD_K, dlci->k);
612
613 return 0;
614}
615
616/**
617 * gsm_register_devices - register all tty devices for a given mux index
618 *
619 * @driver: the tty driver that describes the tty devices
620 * @index: the mux number is used to calculate the minor numbers of the
621 * ttys for this mux and may differ from the position in the
622 * mux array.
623 */
624static int gsm_register_devices(struct tty_driver *driver, unsigned int index)
625{
626 struct device *dev;
627 int i;
628 unsigned int base;
629
630 if (!driver || index >= MAX_MUX)
631 return -EINVAL;
632
633 base = index * NUM_DLCI; /* first minor for this index */
634 for (i = 1; i < NUM_DLCI; i++) {
635 /* Don't register device 0 - this is the control channel
636 * and not a usable tty interface
637 */
638 dev = tty_register_device(gsm_tty_driver, base + i, NULL);
639 if (IS_ERR(dev)) {
640 if (debug & DBG_ERRORS)
641 pr_info("%s failed to register device minor %u",
642 __func__, base + i);
643 for (i--; i >= 1; i--)
644 tty_unregister_device(gsm_tty_driver, base + i);
645 return PTR_ERR(dev);
646 }
647 }
648
649 return 0;
650}
651
652/**
653 * gsm_unregister_devices - unregister all tty devices for a given mux index
654 *
655 * @driver: the tty driver that describes the tty devices
656 * @index: the mux number is used to calculate the minor numbers of the
657 * ttys for this mux and may differ from the position in the
658 * mux array.
659 */
660static void gsm_unregister_devices(struct tty_driver *driver,
661 unsigned int index)
662{
663 int i;
664 unsigned int base;
665
666 if (!driver || index >= MAX_MUX)
667 return;
668
669 base = index * NUM_DLCI; /* first minor for this index */
670 for (i = 1; i < NUM_DLCI; i++) {
671 /* Don't unregister device 0 - this is the control
672 * channel and not a usable tty interface
673 */
674 tty_unregister_device(gsm_tty_driver, base + i);
675 }
676}
677
678/**
679 * gsm_print_packet - display a frame for debug
680 * @hdr: header to print before decode
681 * @addr: address EA from the frame
682 * @cr: C/R bit seen as initiator
683 * @control: control including PF bit
684 * @data: following data bytes
685 * @dlen: length of data
686 *
687 * Displays a packet in human readable format for debugging purposes. The
688 * style is based on amateur radio LAP-B dump display.
689 */
690
691static void gsm_print_packet(const char *hdr, int addr, int cr,
692 u8 control, const u8 *data, int dlen)
693{
694 if (!(debug & DBG_DUMP))
695 return;
696 /* Only show user payload frames if debug & DBG_PAYLOAD */
697 if (!(debug & DBG_PAYLOAD) && addr != 0)
698 if ((control & ~PF) == UI || (control & ~PF) == UIH)
699 return;
700
701 pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
702
703 switch (control & ~PF) {
704 case SABM:
705 pr_cont("SABM");
706 break;
707 case UA:
708 pr_cont("UA");
709 break;
710 case DISC:
711 pr_cont("DISC");
712 break;
713 case DM:
714 pr_cont("DM");
715 break;
716 case UI:
717 pr_cont("UI");
718 break;
719 case UIH:
720 pr_cont("UIH");
721 break;
722 default:
723 if (!(control & 0x01)) {
724 pr_cont("I N(S)%d N(R)%d",
725 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
726 } else switch (control & 0x0F) {
727 case RR:
728 pr_cont("RR(%d)", (control & 0xE0) >> 5);
729 break;
730 case RNR:
731 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
732 break;
733 case REJ:
734 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
735 break;
736 default:
737 pr_cont("[%02X]", control);
738 }
739 }
740
741 if (control & PF)
742 pr_cont("(P)");
743 else
744 pr_cont("(F)");
745
746 gsm_hex_dump_bytes(NULL, data, dlen);
747}
748
749
750/*
751 * Link level transmission side
752 */
753
754/**
755 * gsm_stuff_frame - bytestuff a packet
756 * @input: input buffer
757 * @output: output buffer
758 * @len: length of input
759 *
760 * Expand a buffer by bytestuffing it. The worst case size change
761 * is doubling and the caller is responsible for handing out
762 * suitable sized buffers.
763 */
764
765static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
766{
767 int olen = 0;
768 while (len--) {
769 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
770 || (*input & ISO_IEC_646_MASK) == XON
771 || (*input & ISO_IEC_646_MASK) == XOFF) {
772 *output++ = GSM1_ESCAPE;
773 *output++ = *input++ ^ GSM1_ESCAPE_BITS;
774 olen++;
775 } else
776 *output++ = *input++;
777 olen++;
778 }
779 return olen;
780}
781
782/**
783 * gsm_send - send a control frame
784 * @gsm: our GSM mux
785 * @addr: address for control frame
786 * @cr: command/response bit seen as initiator
787 * @control: control byte including PF bit
788 *
789 * Format up and transmit a control frame. These should be transmitted
790 * ahead of data when they are needed.
791 */
792static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
793{
794 struct gsm_msg *msg;
795 u8 *dp;
796 int ocr;
797 unsigned long flags;
798
799 msg = gsm_data_alloc(gsm, addr, 0, control);
800 if (!msg)
801 return -ENOMEM;
802
803 /* toggle C/R coding if not initiator */
804 ocr = cr ^ (gsm->initiator ? 0 : 1);
805
806 msg->data -= 3;
807 dp = msg->data;
808 *dp++ = (addr << 2) | (ocr << 1) | EA;
809 *dp++ = control;
810
811 if (gsm->encoding == GSM_BASIC_OPT)
812 *dp++ = EA; /* Length of data = 0 */
813
814 *dp = 0xFF - gsm_fcs_add_block(INIT_FCS, msg->data, dp - msg->data);
815 msg->len = (dp - msg->data) + 1;
816
817 gsm_print_packet("Q->", addr, cr, control, NULL, 0);
818
819 spin_lock_irqsave(&gsm->tx_lock, flags);
820 list_add_tail(&msg->list, &gsm->tx_ctrl_list);
821 gsm->tx_bytes += msg->len;
822 spin_unlock_irqrestore(&gsm->tx_lock, flags);
823 gsmld_write_trigger(gsm);
824
825 return 0;
826}
827
828/**
829 * gsm_dlci_clear_queues - remove outstanding data for a DLCI
830 * @gsm: mux
831 * @dlci: clear for this DLCI
832 *
833 * Clears the data queues for a given DLCI.
834 */
835static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci)
836{
837 struct gsm_msg *msg, *nmsg;
838 int addr = dlci->addr;
839 unsigned long flags;
840
841 /* Clear DLCI write fifo first */
842 spin_lock_irqsave(&dlci->lock, flags);
843 kfifo_reset(&dlci->fifo);
844 spin_unlock_irqrestore(&dlci->lock, flags);
845
846 /* Clear data packets in MUX write queue */
847 spin_lock_irqsave(&gsm->tx_lock, flags);
848 list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
849 if (msg->addr != addr)
850 continue;
851 gsm->tx_bytes -= msg->len;
852 list_del(&msg->list);
853 kfree(msg);
854 }
855 spin_unlock_irqrestore(&gsm->tx_lock, flags);
856}
857
858/**
859 * gsm_response - send a control response
860 * @gsm: our GSM mux
861 * @addr: address for control frame
862 * @control: control byte including PF bit
863 *
864 * Format up and transmit a link level response frame.
865 */
866
867static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
868{
869 gsm_send(gsm, addr, 0, control);
870}
871
872/**
873 * gsm_command - send a control command
874 * @gsm: our GSM mux
875 * @addr: address for control frame
876 * @control: control byte including PF bit
877 *
878 * Format up and transmit a link level command frame.
879 */
880
881static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
882{
883 gsm_send(gsm, addr, 1, control);
884}
885
886/* Data transmission */
887
888#define HDR_LEN 6 /* ADDR CTRL [LEN.2] DATA FCS */
889
890/**
891 * gsm_data_alloc - allocate data frame
892 * @gsm: GSM mux
893 * @addr: DLCI address
894 * @len: length excluding header and FCS
895 * @ctrl: control byte
896 *
897 * Allocate a new data buffer for sending frames with data. Space is left
898 * at the front for header bytes but that is treated as an implementation
899 * detail and not for the high level code to use
900 */
901
902static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
903 u8 ctrl)
904{
905 struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
906 GFP_ATOMIC);
907 if (m == NULL)
908 return NULL;
909 m->data = m->buffer + HDR_LEN - 1; /* Allow for FCS */
910 m->len = len;
911 m->addr = addr;
912 m->ctrl = ctrl;
913 INIT_LIST_HEAD(&m->list);
914 return m;
915}
916
917/**
918 * gsm_send_packet - sends a single packet
919 * @gsm: GSM Mux
920 * @msg: packet to send
921 *
922 * The given packet is encoded and sent out. No memory is freed.
923 * The caller must hold the gsm tx lock.
924 */
925static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
926{
927 int len, ret;
928
929
930 if (gsm->encoding == GSM_BASIC_OPT) {
931 gsm->txframe[0] = GSM0_SOF;
932 memcpy(gsm->txframe + 1, msg->data, msg->len);
933 gsm->txframe[msg->len + 1] = GSM0_SOF;
934 len = msg->len + 2;
935 } else {
936 gsm->txframe[0] = GSM1_SOF;
937 len = gsm_stuff_frame(msg->data, gsm->txframe + 1, msg->len);
938 gsm->txframe[len + 1] = GSM1_SOF;
939 len += 2;
940 }
941
942 if (debug & DBG_DATA)
943 gsm_hex_dump_bytes(__func__, gsm->txframe, len);
944 gsm_print_packet("-->", msg->addr, gsm->initiator, msg->ctrl, msg->data,
945 msg->len);
946
947 ret = gsmld_output(gsm, gsm->txframe, len);
948 if (ret <= 0)
949 return ret;
950 /* FIXME: Can eliminate one SOF in many more cases */
951 gsm->tx_bytes -= msg->len;
952
953 return 0;
954}
955
956/**
957 * gsm_is_flow_ctrl_msg - checks if flow control message
958 * @msg: message to check
959 *
960 * Returns true if the given message is a flow control command of the
961 * control channel. False is returned in any other case.
962 */
963static bool gsm_is_flow_ctrl_msg(struct gsm_msg *msg)
964{
965 unsigned int cmd;
966
967 if (msg->addr > 0)
968 return false;
969
970 switch (msg->ctrl & ~PF) {
971 case UI:
972 case UIH:
973 cmd = 0;
974 if (gsm_read_ea_val(&cmd, msg->data + 2, msg->len - 2) < 1)
975 break;
976 switch (cmd & ~PF) {
977 case CMD_FCOFF:
978 case CMD_FCON:
979 return true;
980 }
981 break;
982 }
983
984 return false;
985}
986
987/**
988 * gsm_data_kick - poke the queue
989 * @gsm: GSM Mux
990 *
991 * The tty device has called us to indicate that room has appeared in
992 * the transmit queue. Ram more data into the pipe if we have any.
993 * If we have been flow-stopped by a CMD_FCOFF, then we can only
994 * send messages on DLCI0 until CMD_FCON. The caller must hold
995 * the gsm tx lock.
996 */
997static int gsm_data_kick(struct gsm_mux *gsm)
998{
999 struct gsm_msg *msg, *nmsg;
1000 struct gsm_dlci *dlci;
1001 int ret;
1002
1003 clear_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
1004
1005 /* Serialize control messages and control channel messages first */
1006 list_for_each_entry_safe(msg, nmsg, &gsm->tx_ctrl_list, list) {
1007 if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg))
1008 continue;
1009 ret = gsm_send_packet(gsm, msg);
1010 switch (ret) {
1011 case -ENOSPC:
1012 return -ENOSPC;
1013 case -ENODEV:
1014 /* ldisc not open */
1015 gsm->tx_bytes -= msg->len;
1016 list_del(&msg->list);
1017 kfree(msg);
1018 continue;
1019 default:
1020 if (ret >= 0) {
1021 list_del(&msg->list);
1022 kfree(msg);
1023 }
1024 break;
1025 }
1026 }
1027
1028 if (gsm->constipated)
1029 return -EAGAIN;
1030
1031 /* Serialize other channels */
1032 if (list_empty(&gsm->tx_data_list))
1033 return 0;
1034 list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
1035 dlci = gsm->dlci[msg->addr];
1036 /* Send only messages for DLCIs with valid state */
1037 if (dlci->state != DLCI_OPEN) {
1038 gsm->tx_bytes -= msg->len;
1039 list_del(&msg->list);
1040 kfree(msg);
1041 continue;
1042 }
1043 ret = gsm_send_packet(gsm, msg);
1044 switch (ret) {
1045 case -ENOSPC:
1046 return -ENOSPC;
1047 case -ENODEV:
1048 /* ldisc not open */
1049 gsm->tx_bytes -= msg->len;
1050 list_del(&msg->list);
1051 kfree(msg);
1052 continue;
1053 default:
1054 if (ret >= 0) {
1055 list_del(&msg->list);
1056 kfree(msg);
1057 }
1058 break;
1059 }
1060 }
1061
1062 return 1;
1063}
1064
1065/**
1066 * __gsm_data_queue - queue a UI or UIH frame
1067 * @dlci: DLCI sending the data
1068 * @msg: message queued
1069 *
1070 * Add data to the transmit queue and try and get stuff moving
1071 * out of the mux tty if not already doing so. The Caller must hold
1072 * the gsm tx lock.
1073 */
1074
1075static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
1076{
1077 struct gsm_mux *gsm = dlci->gsm;
1078 u8 *dp = msg->data;
1079 u8 *fcs = dp + msg->len;
1080
1081 /* Fill in the header */
1082 if (gsm->encoding == GSM_BASIC_OPT) {
1083 if (msg->len < 128)
1084 *--dp = (msg->len << 1) | EA;
1085 else {
1086 *--dp = (msg->len >> 7); /* bits 7 - 15 */
1087 *--dp = (msg->len & 127) << 1; /* bits 0 - 6 */
1088 }
1089 }
1090
1091 *--dp = msg->ctrl;
1092 if (gsm->initiator)
1093 *--dp = (msg->addr << 2) | CR | EA;
1094 else
1095 *--dp = (msg->addr << 2) | EA;
1096 *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
1097 /* Ugly protocol layering violation */
1098 if (msg->ctrl == UI || msg->ctrl == (UI|PF))
1099 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
1100 *fcs = 0xFF - *fcs;
1101
1102 gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
1103 msg->data, msg->len);
1104
1105 /* Move the header back and adjust the length, also allow for the FCS
1106 now tacked on the end */
1107 msg->len += (msg->data - dp) + 1;
1108 msg->data = dp;
1109
1110 /* Add to the actual output queue */
1111 switch (msg->ctrl & ~PF) {
1112 case UI:
1113 case UIH:
1114 if (msg->addr > 0) {
1115 list_add_tail(&msg->list, &gsm->tx_data_list);
1116 break;
1117 }
1118 fallthrough;
1119 default:
1120 list_add_tail(&msg->list, &gsm->tx_ctrl_list);
1121 break;
1122 }
1123 gsm->tx_bytes += msg->len;
1124
1125 gsmld_write_trigger(gsm);
1126 mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
1127}
1128
1129/**
1130 * gsm_data_queue - queue a UI or UIH frame
1131 * @dlci: DLCI sending the data
1132 * @msg: message queued
1133 *
1134 * Add data to the transmit queue and try and get stuff moving
1135 * out of the mux tty if not already doing so. Take the
1136 * the gsm tx lock and dlci lock.
1137 */
1138
1139static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
1140{
1141 unsigned long flags;
1142 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
1143 __gsm_data_queue(dlci, msg);
1144 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
1145}
1146
1147/**
1148 * gsm_dlci_data_output - try and push data out of a DLCI
1149 * @gsm: mux
1150 * @dlci: the DLCI to pull data from
1151 *
1152 * Pull data from a DLCI and send it into the transmit queue if there
1153 * is data. Keep to the MRU of the mux. This path handles the usual tty
1154 * interface which is a byte stream with optional modem data.
1155 *
1156 * Caller must hold the tx_lock of the mux.
1157 */
1158
1159static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
1160{
1161 struct gsm_msg *msg;
1162 u8 *dp;
1163 int h, len, size;
1164
1165 /* for modem bits without break data */
1166 h = ((dlci->adaption == 1) ? 0 : 1);
1167
1168 len = kfifo_len(&dlci->fifo);
1169 if (len == 0)
1170 return 0;
1171
1172 /* MTU/MRU count only the data bits but watch adaption mode */
1173 if ((len + h) > dlci->mtu)
1174 len = dlci->mtu - h;
1175
1176 size = len + h;
1177
1178 msg = gsm_data_alloc(gsm, dlci->addr, size, dlci->ftype);
1179 if (!msg)
1180 return -ENOMEM;
1181 dp = msg->data;
1182 switch (dlci->adaption) {
1183 case 1: /* Unstructured */
1184 break;
1185 case 2: /* Unstructured with modem bits.
1186 * Always one byte as we never send inline break data
1187 */
1188 *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
1189 break;
1190 default:
1191 pr_err("%s: unsupported adaption %d\n", __func__,
1192 dlci->adaption);
1193 break;
1194 }
1195
1196 WARN_ON(len != kfifo_out_locked(&dlci->fifo, dp, len,
1197 &dlci->lock));
1198
1199 /* Notify upper layer about available send space. */
1200 tty_port_tty_wakeup(&dlci->port);
1201
1202 __gsm_data_queue(dlci, msg);
1203 /* Bytes of data we used up */
1204 return size;
1205}
1206
1207/**
1208 * gsm_dlci_data_output_framed - try and push data out of a DLCI
1209 * @gsm: mux
1210 * @dlci: the DLCI to pull data from
1211 *
1212 * Pull data from a DLCI and send it into the transmit queue if there
1213 * is data. Keep to the MRU of the mux. This path handles framed data
1214 * queued as skbuffs to the DLCI.
1215 *
1216 * Caller must hold the tx_lock of the mux.
1217 */
1218
1219static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
1220 struct gsm_dlci *dlci)
1221{
1222 struct gsm_msg *msg;
1223 u8 *dp;
1224 int len, size;
1225 int last = 0, first = 0;
1226 int overhead = 0;
1227
1228 /* One byte per frame is used for B/F flags */
1229 if (dlci->adaption == 4)
1230 overhead = 1;
1231
1232 /* dlci->skb is locked by tx_lock */
1233 if (dlci->skb == NULL) {
1234 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
1235 if (dlci->skb == NULL)
1236 return 0;
1237 first = 1;
1238 }
1239 len = dlci->skb->len + overhead;
1240
1241 /* MTU/MRU count only the data bits */
1242 if (len > dlci->mtu) {
1243 if (dlci->adaption == 3) {
1244 /* Over long frame, bin it */
1245 dev_kfree_skb_any(dlci->skb);
1246 dlci->skb = NULL;
1247 return 0;
1248 }
1249 len = dlci->mtu;
1250 } else
1251 last = 1;
1252
1253 size = len + overhead;
1254 msg = gsm_data_alloc(gsm, dlci->addr, size, dlci->ftype);
1255 if (msg == NULL) {
1256 skb_queue_tail(&dlci->skb_list, dlci->skb);
1257 dlci->skb = NULL;
1258 return -ENOMEM;
1259 }
1260 dp = msg->data;
1261
1262 if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
1263 /* Flag byte to carry the start/end info */
1264 *dp++ = last << 7 | first << 6 | 1; /* EA */
1265 len--;
1266 }
1267 memcpy(dp, dlci->skb->data, len);
1268 skb_pull(dlci->skb, len);
1269 __gsm_data_queue(dlci, msg);
1270 if (last) {
1271 dev_kfree_skb_any(dlci->skb);
1272 dlci->skb = NULL;
1273 }
1274 return size;
1275}
1276
1277/**
1278 * gsm_dlci_modem_output - try and push modem status out of a DLCI
1279 * @gsm: mux
1280 * @dlci: the DLCI to pull modem status from
1281 * @brk: break signal
1282 *
1283 * Push an empty frame in to the transmit queue to update the modem status
1284 * bits and to transmit an optional break.
1285 *
1286 * Caller must hold the tx_lock of the mux.
1287 */
1288
1289static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
1290 u8 brk)
1291{
1292 u8 *dp = NULL;
1293 struct gsm_msg *msg;
1294 int size = 0;
1295
1296 /* for modem bits without break data */
1297 switch (dlci->adaption) {
1298 case 1: /* Unstructured */
1299 break;
1300 case 2: /* Unstructured with modem bits. */
1301 size++;
1302 if (brk > 0)
1303 size++;
1304 break;
1305 default:
1306 pr_err("%s: unsupported adaption %d\n", __func__,
1307 dlci->adaption);
1308 return -EINVAL;
1309 }
1310
1311 msg = gsm_data_alloc(gsm, dlci->addr, size, dlci->ftype);
1312 if (!msg) {
1313 pr_err("%s: gsm_data_alloc error", __func__);
1314 return -ENOMEM;
1315 }
1316 dp = msg->data;
1317 switch (dlci->adaption) {
1318 case 1: /* Unstructured */
1319 break;
1320 case 2: /* Unstructured with modem bits. */
1321 if (brk == 0) {
1322 *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
1323 } else {
1324 *dp++ = gsm_encode_modem(dlci) << 1;
1325 *dp++ = (brk << 4) | 2 | EA; /* Length, Break, EA */
1326 }
1327 break;
1328 default:
1329 /* Handled above */
1330 break;
1331 }
1332
1333 __gsm_data_queue(dlci, msg);
1334 return size;
1335}
1336
1337/**
1338 * gsm_dlci_data_sweep - look for data to send
1339 * @gsm: the GSM mux
1340 *
1341 * Sweep the GSM mux channels in priority order looking for ones with
1342 * data to send. We could do with optimising this scan a bit. We aim
1343 * to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
1344 * TX_THRESH_LO we get called again
1345 *
1346 * FIXME: We should round robin between groups and in theory you can
1347 * renegotiate DLCI priorities with optional stuff. Needs optimising.
1348 */
1349
1350static int gsm_dlci_data_sweep(struct gsm_mux *gsm)
1351{
1352 /* Priority ordering: We should do priority with RR of the groups */
1353 int i, len, ret = 0;
1354 bool sent;
1355 struct gsm_dlci *dlci;
1356
1357 while (gsm->tx_bytes < TX_THRESH_HI) {
1358 for (sent = false, i = 1; i < NUM_DLCI; i++) {
1359 dlci = gsm->dlci[i];
1360 /* skip unused or blocked channel */
1361 if (!dlci || dlci->constipated)
1362 continue;
1363 /* skip channels with invalid state */
1364 if (dlci->state != DLCI_OPEN)
1365 continue;
1366 /* count the sent data per adaption */
1367 if (dlci->adaption < 3 && !dlci->net)
1368 len = gsm_dlci_data_output(gsm, dlci);
1369 else
1370 len = gsm_dlci_data_output_framed(gsm, dlci);
1371 /* on error exit */
1372 if (len < 0)
1373 return ret;
1374 if (len > 0) {
1375 ret++;
1376 sent = true;
1377 /* The lower DLCs can starve the higher DLCs! */
1378 break;
1379 }
1380 /* try next */
1381 }
1382 if (!sent)
1383 break;
1384 }
1385
1386 return ret;
1387}
1388
1389/**
1390 * gsm_dlci_data_kick - transmit if possible
1391 * @dlci: DLCI to kick
1392 *
1393 * Transmit data from this DLCI if the queue is empty. We can't rely on
1394 * a tty wakeup except when we filled the pipe so we need to fire off
1395 * new data ourselves in other cases.
1396 */
1397
1398static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
1399{
1400 unsigned long flags;
1401 int sweep;
1402
1403 if (dlci->constipated)
1404 return;
1405
1406 spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
1407 /* If we have nothing running then we need to fire up */
1408 sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
1409 if (dlci->gsm->tx_bytes == 0) {
1410 if (dlci->net)
1411 gsm_dlci_data_output_framed(dlci->gsm, dlci);
1412 else
1413 gsm_dlci_data_output(dlci->gsm, dlci);
1414 }
1415 if (sweep)
1416 gsm_dlci_data_sweep(dlci->gsm);
1417 spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
1418}
1419
1420/*
1421 * Control message processing
1422 */
1423
1424
1425/**
1426 * gsm_control_command - send a command frame to a control
1427 * @gsm: gsm channel
1428 * @cmd: the command to use
1429 * @data: data to follow encoded info
1430 * @dlen: length of data
1431 *
1432 * Encode up and queue a UI/UIH frame containing our command.
1433 */
1434static int gsm_control_command(struct gsm_mux *gsm, int cmd, const u8 *data,
1435 int dlen)
1436{
1437 struct gsm_msg *msg;
1438
1439 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->dlci[0]->ftype);
1440 if (msg == NULL)
1441 return -ENOMEM;
1442
1443 msg->data[0] = (cmd << 1) | CR | EA; /* Set C/R */
1444 msg->data[1] = (dlen << 1) | EA;
1445 memcpy(msg->data + 2, data, dlen);
1446 gsm_data_queue(gsm->dlci[0], msg);
1447
1448 return 0;
1449}
1450
1451/**
1452 * gsm_control_reply - send a response frame to a control
1453 * @gsm: gsm channel
1454 * @cmd: the command to use
1455 * @data: data to follow encoded info
1456 * @dlen: length of data
1457 *
1458 * Encode up and queue a UI/UIH frame containing our response.
1459 */
1460
1461static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
1462 int dlen)
1463{
1464 struct gsm_msg *msg;
1465
1466 msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->dlci[0]->ftype);
1467 if (msg == NULL)
1468 return;
1469 msg->data[0] = (cmd & 0xFE) << 1 | EA; /* Clear C/R */
1470 msg->data[1] = (dlen << 1) | EA;
1471 memcpy(msg->data + 2, data, dlen);
1472 gsm_data_queue(gsm->dlci[0], msg);
1473}
1474
1475/**
1476 * gsm_process_modem - process received modem status
1477 * @tty: virtual tty bound to the DLCI
1478 * @dlci: DLCI to affect
1479 * @modem: modem bits (full EA)
1480 * @slen: number of signal octets
1481 *
1482 * Used when a modem control message or line state inline in adaption
1483 * layer 2 is processed. Sort out the local modem state and throttles
1484 */
1485
1486static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1487 u32 modem, int slen)
1488{
1489 int mlines = 0;
1490 u8 brk = 0;
1491 int fc;
1492
1493 /* The modem status command can either contain one octet (V.24 signals)
1494 * or two octets (V.24 signals + break signals). This is specified in
1495 * section 5.4.6.3.7 of the 07.10 mux spec.
1496 */
1497
1498 if (slen == 1)
1499 modem = modem & 0x7f;
1500 else {
1501 brk = modem & 0x7f;
1502 modem = (modem >> 7) & 0x7f;
1503 }
1504
1505 /* Flow control/ready to communicate */
1506 fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1507 if (fc && !dlci->constipated) {
1508 /* Need to throttle our output on this device */
1509 dlci->constipated = true;
1510 } else if (!fc && dlci->constipated) {
1511 dlci->constipated = false;
1512 gsm_dlci_data_kick(dlci);
1513 }
1514
1515 /* Map modem bits */
1516 if (modem & MDM_RTC)
1517 mlines |= TIOCM_DSR | TIOCM_DTR;
1518 if (modem & MDM_RTR)
1519 mlines |= TIOCM_RTS | TIOCM_CTS;
1520 if (modem & MDM_IC)
1521 mlines |= TIOCM_RI;
1522 if (modem & MDM_DV)
1523 mlines |= TIOCM_CD;
1524
1525 /* Carrier drop -> hangup */
1526 if (tty) {
1527 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1528 if (!C_CLOCAL(tty))
1529 tty_hangup(tty);
1530 }
1531 if (brk & 0x01)
1532 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1533 dlci->modem_rx = mlines;
1534}
1535
1536/**
1537 * gsm_process_negotiation - process received parameters
1538 * @gsm: GSM channel
1539 * @addr: DLCI address
1540 * @cr: command/response
1541 * @params: encoded parameters from the parameter negotiation message
1542 *
1543 * Used when the response for our parameter negotiation command was
1544 * received.
1545 */
1546static int gsm_process_negotiation(struct gsm_mux *gsm, unsigned int addr,
1547 unsigned int cr,
1548 const struct gsm_dlci_param_bits *params)
1549{
1550 struct gsm_dlci *dlci = gsm->dlci[addr];
1551 unsigned int ftype, i, adaption, prio, n1, k;
1552
1553 i = FIELD_GET(PN_I_CL_FIELD_FTYPE, params->i_cl_bits);
1554 adaption = FIELD_GET(PN_I_CL_FIELD_ADAPTION, params->i_cl_bits) + 1;
1555 prio = FIELD_GET(PN_P_FIELD_PRIO, params->p_bits);
1556 n1 = FIELD_GET(PN_N_FIELD_N1, get_unaligned_le16(¶ms->n_bits));
1557 k = FIELD_GET(PN_K_FIELD_K, params->k_bits);
1558
1559 if (n1 < MIN_MTU) {
1560 if (debug & DBG_ERRORS)
1561 pr_info("%s N1 out of range in PN\n", __func__);
1562 return -EINVAL;
1563 }
1564
1565 switch (i) {
1566 case 0x00:
1567 ftype = UIH;
1568 break;
1569 case 0x01:
1570 ftype = UI;
1571 break;
1572 case 0x02: /* I frames are not supported */
1573 if (debug & DBG_ERRORS)
1574 pr_info("%s unsupported I frame request in PN\n",
1575 __func__);
1576 return -EINVAL;
1577 default:
1578 if (debug & DBG_ERRORS)
1579 pr_info("%s i out of range in PN\n", __func__);
1580 return -EINVAL;
1581 }
1582
1583 if (!cr && gsm->initiator) {
1584 if (adaption != dlci->adaption) {
1585 if (debug & DBG_ERRORS)
1586 pr_info("%s invalid adaption %d in PN\n",
1587 __func__, adaption);
1588 return -EINVAL;
1589 }
1590 if (prio != dlci->prio) {
1591 if (debug & DBG_ERRORS)
1592 pr_info("%s invalid priority %d in PN",
1593 __func__, prio);
1594 return -EINVAL;
1595 }
1596 if (n1 > gsm->mru || n1 > dlci->mtu) {
1597 /* We requested a frame size but the other party wants
1598 * to send larger frames. The standard allows only a
1599 * smaller response value than requested (5.4.6.3.1).
1600 */
1601 if (debug & DBG_ERRORS)
1602 pr_info("%s invalid N1 %d in PN\n", __func__,
1603 n1);
1604 return -EINVAL;
1605 }
1606 dlci->mtu = n1;
1607 if (ftype != dlci->ftype) {
1608 if (debug & DBG_ERRORS)
1609 pr_info("%s invalid i %d in PN\n", __func__, i);
1610 return -EINVAL;
1611 }
1612 if (ftype != UI && ftype != UIH && k > dlci->k) {
1613 if (debug & DBG_ERRORS)
1614 pr_info("%s invalid k %d in PN\n", __func__, k);
1615 return -EINVAL;
1616 }
1617 dlci->k = k;
1618 } else if (cr && !gsm->initiator) {
1619 /* Only convergence layer type 1 and 2 are supported. */
1620 if (adaption != 1 && adaption != 2) {
1621 if (debug & DBG_ERRORS)
1622 pr_info("%s invalid adaption %d in PN\n",
1623 __func__, adaption);
1624 return -EINVAL;
1625 }
1626 dlci->adaption = adaption;
1627 if (n1 > gsm->mru) {
1628 /* Propose a smaller value */
1629 dlci->mtu = gsm->mru;
1630 } else if (n1 > MAX_MTU) {
1631 /* Propose a smaller value */
1632 dlci->mtu = MAX_MTU;
1633 } else {
1634 dlci->mtu = n1;
1635 }
1636 dlci->prio = prio;
1637 dlci->ftype = ftype;
1638 dlci->k = k;
1639 } else {
1640 return -EINVAL;
1641 }
1642
1643 return 0;
1644}
1645
1646/**
1647 * gsm_control_modem - modem status received
1648 * @gsm: GSM channel
1649 * @data: data following command
1650 * @clen: command length
1651 *
1652 * We have received a modem status control message. This is used by
1653 * the GSM mux protocol to pass virtual modem line status and optionally
1654 * to indicate break signals. Unpack it, convert to Linux representation
1655 * and if need be stuff a break message down the tty.
1656 */
1657
1658static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1659{
1660 unsigned int addr = 0;
1661 unsigned int modem = 0;
1662 struct gsm_dlci *dlci;
1663 int len = clen;
1664 int cl = clen;
1665 const u8 *dp = data;
1666 struct tty_struct *tty;
1667
1668 len = gsm_read_ea_val(&addr, data, cl);
1669 if (len < 1)
1670 return;
1671
1672 addr >>= 1;
1673 /* Closed port, or invalid ? */
1674 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1675 return;
1676 dlci = gsm->dlci[addr];
1677
1678 /* Must be at least one byte following the EA */
1679 if ((cl - len) < 1)
1680 return;
1681
1682 dp += len;
1683 cl -= len;
1684
1685 /* get the modem status */
1686 len = gsm_read_ea_val(&modem, dp, cl);
1687 if (len < 1)
1688 return;
1689
1690 tty = tty_port_tty_get(&dlci->port);
1691 gsm_process_modem(tty, dlci, modem, cl);
1692 if (tty) {
1693 tty_wakeup(tty);
1694 tty_kref_put(tty);
1695 }
1696 gsm_control_reply(gsm, CMD_MSC, data, clen);
1697}
1698
1699/**
1700 * gsm_control_negotiation - parameter negotiation received
1701 * @gsm: GSM channel
1702 * @cr: command/response flag
1703 * @data: data following command
1704 * @dlen: data length
1705 *
1706 * We have received a parameter negotiation message. This is used by
1707 * the GSM mux protocol to configure protocol parameters for a new DLCI.
1708 */
1709static void gsm_control_negotiation(struct gsm_mux *gsm, unsigned int cr,
1710 const u8 *data, unsigned int dlen)
1711{
1712 unsigned int addr;
1713 struct gsm_dlci_param_bits pn_reply;
1714 struct gsm_dlci *dlci;
1715 struct gsm_dlci_param_bits *params;
1716
1717 if (dlen < sizeof(struct gsm_dlci_param_bits))
1718 return;
1719
1720 /* Invalid DLCI? */
1721 params = (struct gsm_dlci_param_bits *)data;
1722 addr = FIELD_GET(PN_D_FIELD_DLCI, params->d_bits);
1723 if (addr == 0 || addr >= NUM_DLCI || !gsm->dlci[addr])
1724 return;
1725 dlci = gsm->dlci[addr];
1726
1727 /* Too late for parameter negotiation? */
1728 if ((!cr && dlci->state == DLCI_OPENING) || dlci->state == DLCI_OPEN)
1729 return;
1730
1731 /* Process the received parameters */
1732 if (gsm_process_negotiation(gsm, addr, cr, params) != 0) {
1733 /* Negotiation failed. Close the link. */
1734 if (debug & DBG_ERRORS)
1735 pr_info("%s PN failed\n", __func__);
1736 gsm_dlci_close(dlci);
1737 return;
1738 }
1739
1740 if (cr) {
1741 /* Reply command with accepted parameters. */
1742 if (gsm_encode_params(dlci, &pn_reply) == 0)
1743 gsm_control_reply(gsm, CMD_PN, (const u8 *)&pn_reply,
1744 sizeof(pn_reply));
1745 else if (debug & DBG_ERRORS)
1746 pr_info("%s PN invalid\n", __func__);
1747 } else if (dlci->state == DLCI_CONFIGURE) {
1748 /* Proceed with link setup by sending SABM before UA */
1749 dlci->state = DLCI_OPENING;
1750 gsm_command(gsm, dlci->addr, SABM|PF);
1751 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1752 } else {
1753 if (debug & DBG_ERRORS)
1754 pr_info("%s PN in invalid state\n", __func__);
1755 }
1756}
1757
1758/**
1759 * gsm_control_rls - remote line status
1760 * @gsm: GSM channel
1761 * @data: data bytes
1762 * @clen: data length
1763 *
1764 * The modem sends us a two byte message on the control channel whenever
1765 * it wishes to send us an error state from the virtual link. Stuff
1766 * this into the uplink tty if present
1767 */
1768
1769static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1770{
1771 struct tty_port *port;
1772 unsigned int addr = 0;
1773 u8 bits;
1774 int len = clen;
1775 const u8 *dp = data;
1776
1777 while (gsm_read_ea(&addr, *dp++) == 0) {
1778 len--;
1779 if (len == 0)
1780 return;
1781 }
1782 /* Must be at least one byte following ea */
1783 len--;
1784 if (len <= 0)
1785 return;
1786 addr >>= 1;
1787 /* Closed port, or invalid ? */
1788 if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1789 return;
1790 /* No error ? */
1791 bits = *dp;
1792 if ((bits & 1) == 0)
1793 return;
1794
1795 port = &gsm->dlci[addr]->port;
1796
1797 if (bits & 2)
1798 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1799 if (bits & 4)
1800 tty_insert_flip_char(port, 0, TTY_PARITY);
1801 if (bits & 8)
1802 tty_insert_flip_char(port, 0, TTY_FRAME);
1803
1804 tty_flip_buffer_push(port);
1805
1806 gsm_control_reply(gsm, CMD_RLS, data, clen);
1807}
1808
1809static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1810
1811/**
1812 * gsm_control_message - DLCI 0 control processing
1813 * @gsm: our GSM mux
1814 * @command: the command EA
1815 * @data: data beyond the command/length EAs
1816 * @clen: length
1817 *
1818 * Input processor for control messages from the other end of the link.
1819 * Processes the incoming request and queues a response frame or an
1820 * NSC response if not supported
1821 */
1822
1823static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1824 const u8 *data, int clen)
1825{
1826 u8 buf[1];
1827
1828 switch (command) {
1829 case CMD_CLD: {
1830 struct gsm_dlci *dlci = gsm->dlci[0];
1831 /* Modem wishes to close down */
1832 if (dlci) {
1833 dlci->dead = true;
1834 gsm->dead = true;
1835 gsm_dlci_begin_close(dlci);
1836 }
1837 }
1838 break;
1839 case CMD_TEST:
1840 /* Modem wishes to test, reply with the data */
1841 gsm_control_reply(gsm, CMD_TEST, data, clen);
1842 break;
1843 case CMD_FCON:
1844 /* Modem can accept data again */
1845 gsm->constipated = false;
1846 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1847 /* Kick the link in case it is idling */
1848 gsmld_write_trigger(gsm);
1849 break;
1850 case CMD_FCOFF:
1851 /* Modem wants us to STFU */
1852 gsm->constipated = true;
1853 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1854 break;
1855 case CMD_MSC:
1856 /* Out of band modem line change indicator for a DLCI */
1857 gsm_control_modem(gsm, data, clen);
1858 break;
1859 case CMD_RLS:
1860 /* Out of band error reception for a DLCI */
1861 gsm_control_rls(gsm, data, clen);
1862 break;
1863 case CMD_PSC:
1864 /* Modem wishes to enter power saving state */
1865 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1866 break;
1867 /* Optional commands */
1868 case CMD_PN:
1869 /* Modem sends a parameter negotiation command */
1870 gsm_control_negotiation(gsm, 1, data, clen);
1871 break;
1872 /* Optional unsupported commands */
1873 case CMD_RPN: /* Remote port negotiation */
1874 case CMD_SNC: /* Service negotiation command */
1875 default:
1876 /* Reply to bad commands with an NSC */
1877 buf[0] = command;
1878 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1879 break;
1880 }
1881}
1882
1883/**
1884 * gsm_control_response - process a response to our control
1885 * @gsm: our GSM mux
1886 * @command: the command (response) EA
1887 * @data: data beyond the command/length EA
1888 * @clen: length
1889 *
1890 * Process a response to an outstanding command. We only allow a single
1891 * control message in flight so this is fairly easy. All the clean up
1892 * is done by the caller, we just update the fields, flag it as done
1893 * and return
1894 */
1895
1896static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1897 const u8 *data, int clen)
1898{
1899 struct gsm_control *ctrl;
1900 unsigned long flags;
1901
1902 spin_lock_irqsave(&gsm->control_lock, flags);
1903
1904 ctrl = gsm->pending_cmd;
1905 command |= 1;
1906 /* Does the reply match our command */
1907 if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1908 /* Our command was replied to, kill the retry timer */
1909 del_timer(&gsm->t2_timer);
1910 gsm->pending_cmd = NULL;
1911 /* Rejected by the other end */
1912 if (command == CMD_NSC)
1913 ctrl->error = -EOPNOTSUPP;
1914 ctrl->done = 1;
1915 wake_up(&gsm->event);
1916 /* Or did we receive the PN response to our PN command */
1917 } else if (command == CMD_PN) {
1918 gsm_control_negotiation(gsm, 0, data, clen);
1919 }
1920 spin_unlock_irqrestore(&gsm->control_lock, flags);
1921}
1922
1923/**
1924 * gsm_control_transmit - send control packet
1925 * @gsm: gsm mux
1926 * @ctrl: frame to send
1927 *
1928 * Send out a pending control command (called under control lock)
1929 */
1930
1931static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1932{
1933 gsm_control_command(gsm, ctrl->cmd, ctrl->data, ctrl->len);
1934}
1935
1936/**
1937 * gsm_control_retransmit - retransmit a control frame
1938 * @t: timer contained in our gsm object
1939 *
1940 * Called off the T2 timer expiry in order to retransmit control frames
1941 * that have been lost in the system somewhere. The control_lock protects
1942 * us from colliding with another sender or a receive completion event.
1943 * In that situation the timer may still occur in a small window but
1944 * gsm->pending_cmd will be NULL and we just let the timer expire.
1945 */
1946
1947static void gsm_control_retransmit(struct timer_list *t)
1948{
1949 struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
1950 struct gsm_control *ctrl;
1951 unsigned long flags;
1952 spin_lock_irqsave(&gsm->control_lock, flags);
1953 ctrl = gsm->pending_cmd;
1954 if (ctrl) {
1955 if (gsm->cretries == 0 || !gsm->dlci[0] || gsm->dlci[0]->dead) {
1956 gsm->pending_cmd = NULL;
1957 ctrl->error = -ETIMEDOUT;
1958 ctrl->done = 1;
1959 spin_unlock_irqrestore(&gsm->control_lock, flags);
1960 wake_up(&gsm->event);
1961 return;
1962 }
1963 gsm->cretries--;
1964 gsm_control_transmit(gsm, ctrl);
1965 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1966 }
1967 spin_unlock_irqrestore(&gsm->control_lock, flags);
1968}
1969
1970/**
1971 * gsm_control_send - send a control frame on DLCI 0
1972 * @gsm: the GSM channel
1973 * @command: command to send including CR bit
1974 * @data: bytes of data (must be kmalloced)
1975 * @clen: length of the block to send
1976 *
1977 * Queue and dispatch a control command. Only one command can be
1978 * active at a time. In theory more can be outstanding but the matching
1979 * gets really complicated so for now stick to one outstanding.
1980 */
1981
1982static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1983 unsigned int command, u8 *data, int clen)
1984{
1985 struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1986 GFP_ATOMIC);
1987 unsigned long flags;
1988 if (ctrl == NULL)
1989 return NULL;
1990retry:
1991 wait_event(gsm->event, gsm->pending_cmd == NULL);
1992 spin_lock_irqsave(&gsm->control_lock, flags);
1993 if (gsm->pending_cmd != NULL) {
1994 spin_unlock_irqrestore(&gsm->control_lock, flags);
1995 goto retry;
1996 }
1997 ctrl->cmd = command;
1998 ctrl->data = data;
1999 ctrl->len = clen;
2000 gsm->pending_cmd = ctrl;
2001
2002 /* If DLCI0 is in ADM mode skip retries, it won't respond */
2003 if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
2004 gsm->cretries = 0;
2005 else
2006 gsm->cretries = gsm->n2;
2007
2008 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
2009 gsm_control_transmit(gsm, ctrl);
2010 spin_unlock_irqrestore(&gsm->control_lock, flags);
2011 return ctrl;
2012}
2013
2014/**
2015 * gsm_control_wait - wait for a control to finish
2016 * @gsm: GSM mux
2017 * @control: control we are waiting on
2018 *
2019 * Waits for the control to complete or time out. Frees any used
2020 * resources and returns 0 for success, or an error if the remote
2021 * rejected or ignored the request.
2022 */
2023
2024static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
2025{
2026 int err;
2027 wait_event(gsm->event, control->done == 1);
2028 err = control->error;
2029 kfree(control);
2030 return err;
2031}
2032
2033
2034/*
2035 * DLCI level handling: Needs krefs
2036 */
2037
2038/*
2039 * State transitions and timers
2040 */
2041
2042/**
2043 * gsm_dlci_close - a DLCI has closed
2044 * @dlci: DLCI that closed
2045 *
2046 * Perform processing when moving a DLCI into closed state. If there
2047 * is an attached tty this is hung up
2048 */
2049
2050static void gsm_dlci_close(struct gsm_dlci *dlci)
2051{
2052 del_timer(&dlci->t1);
2053 if (debug & DBG_ERRORS)
2054 pr_debug("DLCI %d goes closed.\n", dlci->addr);
2055 dlci->state = DLCI_CLOSED;
2056 /* Prevent us from sending data before the link is up again */
2057 dlci->constipated = true;
2058 if (dlci->addr != 0) {
2059 tty_port_tty_hangup(&dlci->port, false);
2060 gsm_dlci_clear_queues(dlci->gsm, dlci);
2061 /* Ensure that gsmtty_open() can return. */
2062 tty_port_set_initialized(&dlci->port, 0);
2063 wake_up_interruptible(&dlci->port.open_wait);
2064 } else
2065 dlci->gsm->dead = true;
2066 /* A DLCI 0 close is a MUX termination so we need to kick that
2067 back to userspace somehow */
2068 gsm_dlci_data_kick(dlci);
2069 wake_up(&dlci->gsm->event);
2070}
2071
2072/**
2073 * gsm_dlci_open - a DLCI has opened
2074 * @dlci: DLCI that opened
2075 *
2076 * Perform processing when moving a DLCI into open state.
2077 */
2078
2079static void gsm_dlci_open(struct gsm_dlci *dlci)
2080{
2081 /* Note that SABM UA .. SABM UA first UA lost can mean that we go
2082 open -> open */
2083 del_timer(&dlci->t1);
2084 /* This will let a tty open continue */
2085 dlci->state = DLCI_OPEN;
2086 dlci->constipated = false;
2087 if (debug & DBG_ERRORS)
2088 pr_debug("DLCI %d goes open.\n", dlci->addr);
2089 /* Send current modem state */
2090 if (dlci->addr)
2091 gsm_modem_update(dlci, 0);
2092 gsm_dlci_data_kick(dlci);
2093 wake_up(&dlci->gsm->event);
2094}
2095
2096/**
2097 * gsm_dlci_negotiate - start parameter negotiation
2098 * @dlci: DLCI to open
2099 *
2100 * Starts the parameter negotiation for the new DLCI. This needs to be done
2101 * before the DLCI initialized the channel via SABM.
2102 */
2103static int gsm_dlci_negotiate(struct gsm_dlci *dlci)
2104{
2105 struct gsm_mux *gsm = dlci->gsm;
2106 struct gsm_dlci_param_bits params;
2107 int ret;
2108
2109 ret = gsm_encode_params(dlci, ¶ms);
2110 if (ret != 0)
2111 return ret;
2112
2113 /* We cannot asynchronous wait for the command response with
2114 * gsm_command() and gsm_control_wait() at this point.
2115 */
2116 ret = gsm_control_command(gsm, CMD_PN, (const u8 *)¶ms,
2117 sizeof(params));
2118
2119 return ret;
2120}
2121
2122/**
2123 * gsm_dlci_t1 - T1 timer expiry
2124 * @t: timer contained in the DLCI that opened
2125 *
2126 * The T1 timer handles retransmits of control frames (essentially of
2127 * SABM and DISC). We resend the command until the retry count runs out
2128 * in which case an opening port goes back to closed and a closing port
2129 * is simply put into closed state (any further frames from the other
2130 * end will get a DM response)
2131 *
2132 * Some control dlci can stay in ADM mode with other dlci working just
2133 * fine. In that case we can just keep the control dlci open after the
2134 * DLCI_OPENING retries time out.
2135 */
2136
2137static void gsm_dlci_t1(struct timer_list *t)
2138{
2139 struct gsm_dlci *dlci = from_timer(dlci, t, t1);
2140 struct gsm_mux *gsm = dlci->gsm;
2141
2142 switch (dlci->state) {
2143 case DLCI_CONFIGURE:
2144 if (dlci->retries && gsm_dlci_negotiate(dlci) == 0) {
2145 dlci->retries--;
2146 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2147 } else {
2148 gsm_dlci_begin_close(dlci); /* prevent half open link */
2149 }
2150 break;
2151 case DLCI_OPENING:
2152 if (dlci->retries) {
2153 dlci->retries--;
2154 gsm_command(dlci->gsm, dlci->addr, SABM|PF);
2155 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2156 } else if (!dlci->addr && gsm->control == (DM | PF)) {
2157 if (debug & DBG_ERRORS)
2158 pr_info("DLCI %d opening in ADM mode.\n",
2159 dlci->addr);
2160 dlci->mode = DLCI_MODE_ADM;
2161 gsm_dlci_open(dlci);
2162 } else {
2163 gsm_dlci_begin_close(dlci); /* prevent half open link */
2164 }
2165
2166 break;
2167 case DLCI_CLOSING:
2168 if (dlci->retries) {
2169 dlci->retries--;
2170 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
2171 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2172 } else
2173 gsm_dlci_close(dlci);
2174 break;
2175 default:
2176 pr_debug("%s: unhandled state: %d\n", __func__, dlci->state);
2177 break;
2178 }
2179}
2180
2181/**
2182 * gsm_dlci_begin_open - start channel open procedure
2183 * @dlci: DLCI to open
2184 *
2185 * Commence opening a DLCI from the Linux side. We issue SABM messages
2186 * to the modem which should then reply with a UA or ADM, at which point
2187 * we will move into open state. Opening is done asynchronously with retry
2188 * running off timers and the responses.
2189 * Parameter negotiation is performed before SABM if required.
2190 */
2191
2192static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
2193{
2194 struct gsm_mux *gsm = dlci ? dlci->gsm : NULL;
2195 bool need_pn = false;
2196
2197 if (!gsm)
2198 return;
2199
2200 if (dlci->addr != 0) {
2201 if (gsm->adaption != 1 || gsm->adaption != dlci->adaption)
2202 need_pn = true;
2203 if (dlci->prio != (roundup(dlci->addr + 1, 8) - 1))
2204 need_pn = true;
2205 if (gsm->ftype != dlci->ftype)
2206 need_pn = true;
2207 }
2208
2209 switch (dlci->state) {
2210 case DLCI_CLOSED:
2211 case DLCI_CLOSING:
2212 dlci->retries = gsm->n2;
2213 if (!need_pn) {
2214 dlci->state = DLCI_OPENING;
2215 gsm_command(gsm, dlci->addr, SABM|PF);
2216 } else {
2217 /* Configure DLCI before setup */
2218 dlci->state = DLCI_CONFIGURE;
2219 if (gsm_dlci_negotiate(dlci) != 0) {
2220 gsm_dlci_close(dlci);
2221 return;
2222 }
2223 }
2224 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2225 break;
2226 default:
2227 break;
2228 }
2229}
2230
2231/**
2232 * gsm_dlci_set_opening - change state to opening
2233 * @dlci: DLCI to open
2234 *
2235 * Change internal state to wait for DLCI open from initiator side.
2236 * We set off timers and responses upon reception of an SABM.
2237 */
2238static void gsm_dlci_set_opening(struct gsm_dlci *dlci)
2239{
2240 switch (dlci->state) {
2241 case DLCI_CLOSED:
2242 case DLCI_CLOSING:
2243 dlci->state = DLCI_OPENING;
2244 break;
2245 default:
2246 break;
2247 }
2248}
2249
2250/**
2251 * gsm_dlci_begin_close - start channel open procedure
2252 * @dlci: DLCI to open
2253 *
2254 * Commence closing a DLCI from the Linux side. We issue DISC messages
2255 * to the modem which should then reply with a UA, at which point we
2256 * will move into closed state. Closing is done asynchronously with retry
2257 * off timers. We may also receive a DM reply from the other end which
2258 * indicates the channel was already closed.
2259 */
2260
2261static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
2262{
2263 struct gsm_mux *gsm = dlci->gsm;
2264 if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
2265 return;
2266 dlci->retries = gsm->n2;
2267 dlci->state = DLCI_CLOSING;
2268 gsm_command(dlci->gsm, dlci->addr, DISC|PF);
2269 mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
2270}
2271
2272/**
2273 * gsm_dlci_data - data arrived
2274 * @dlci: channel
2275 * @data: block of bytes received
2276 * @clen: length of received block
2277 *
2278 * A UI or UIH frame has arrived which contains data for a channel
2279 * other than the control channel. If the relevant virtual tty is
2280 * open we shovel the bits down it, if not we drop them.
2281 */
2282
2283static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
2284{
2285 /* krefs .. */
2286 struct tty_port *port = &dlci->port;
2287 struct tty_struct *tty;
2288 unsigned int modem = 0;
2289 int len;
2290
2291 if (debug & DBG_TTY)
2292 pr_debug("%d bytes for tty\n", clen);
2293 switch (dlci->adaption) {
2294 /* Unsupported types */
2295 case 4: /* Packetised interruptible data */
2296 break;
2297 case 3: /* Packetised uininterruptible voice/data */
2298 break;
2299 case 2: /* Asynchronous serial with line state in each frame */
2300 len = gsm_read_ea_val(&modem, data, clen);
2301 if (len < 1)
2302 return;
2303 tty = tty_port_tty_get(port);
2304 if (tty) {
2305 gsm_process_modem(tty, dlci, modem, len);
2306 tty_wakeup(tty);
2307 tty_kref_put(tty);
2308 }
2309 /* Skip processed modem data */
2310 data += len;
2311 clen -= len;
2312 fallthrough;
2313 case 1: /* Line state will go via DLCI 0 controls only */
2314 default:
2315 tty_insert_flip_string(port, data, clen);
2316 tty_flip_buffer_push(port);
2317 }
2318}
2319
2320/**
2321 * gsm_dlci_command - data arrived on control channel
2322 * @dlci: channel
2323 * @data: block of bytes received
2324 * @len: length of received block
2325 *
2326 * A UI or UIH frame has arrived which contains data for DLCI 0 the
2327 * control channel. This should contain a command EA followed by
2328 * control data bytes. The command EA contains a command/response bit
2329 * and we divide up the work accordingly.
2330 */
2331
2332static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
2333{
2334 /* See what command is involved */
2335 unsigned int command = 0;
2336 unsigned int clen = 0;
2337 unsigned int dlen;
2338
2339 /* read the command */
2340 dlen = gsm_read_ea_val(&command, data, len);
2341 len -= dlen;
2342 data += dlen;
2343
2344 /* read any control data */
2345 dlen = gsm_read_ea_val(&clen, data, len);
2346 len -= dlen;
2347 data += dlen;
2348
2349 /* Malformed command? */
2350 if (clen > len)
2351 return;
2352
2353 if (command & 1)
2354 gsm_control_message(dlci->gsm, command, data, clen);
2355 else
2356 gsm_control_response(dlci->gsm, command, data, clen);
2357}
2358
2359/**
2360 * gsm_kick_timer - transmit if possible
2361 * @t: timer contained in our gsm object
2362 *
2363 * Transmit data from DLCIs if the queue is empty. We can't rely on
2364 * a tty wakeup except when we filled the pipe so we need to fire off
2365 * new data ourselves in other cases.
2366 */
2367static void gsm_kick_timer(struct timer_list *t)
2368{
2369 struct gsm_mux *gsm = from_timer(gsm, t, kick_timer);
2370 unsigned long flags;
2371 int sent = 0;
2372
2373 spin_lock_irqsave(&gsm->tx_lock, flags);
2374 /* If we have nothing running then we need to fire up */
2375 if (gsm->tx_bytes < TX_THRESH_LO)
2376 sent = gsm_dlci_data_sweep(gsm);
2377 spin_unlock_irqrestore(&gsm->tx_lock, flags);
2378
2379 if (sent && debug & DBG_DATA)
2380 pr_info("%s TX queue stalled\n", __func__);
2381}
2382
2383/*
2384 * Allocate/Free DLCI channels
2385 */
2386
2387/**
2388 * gsm_dlci_alloc - allocate a DLCI
2389 * @gsm: GSM mux
2390 * @addr: address of the DLCI
2391 *
2392 * Allocate and install a new DLCI object into the GSM mux.
2393 *
2394 * FIXME: review locking races
2395 */
2396
2397static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
2398{
2399 struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
2400 if (dlci == NULL)
2401 return NULL;
2402 spin_lock_init(&dlci->lock);
2403 mutex_init(&dlci->mutex);
2404 if (kfifo_alloc(&dlci->fifo, TX_SIZE, GFP_KERNEL) < 0) {
2405 kfree(dlci);
2406 return NULL;
2407 }
2408
2409 skb_queue_head_init(&dlci->skb_list);
2410 timer_setup(&dlci->t1, gsm_dlci_t1, 0);
2411 tty_port_init(&dlci->port);
2412 dlci->port.ops = &gsm_port_ops;
2413 dlci->gsm = gsm;
2414 dlci->addr = addr;
2415 dlci->adaption = gsm->adaption;
2416 dlci->mtu = gsm->mtu;
2417 if (addr == 0)
2418 dlci->prio = 0;
2419 else
2420 dlci->prio = roundup(addr + 1, 8) - 1;
2421 dlci->ftype = gsm->ftype;
2422 dlci->k = gsm->k;
2423 dlci->state = DLCI_CLOSED;
2424 if (addr) {
2425 dlci->data = gsm_dlci_data;
2426 /* Prevent us from sending data before the link is up */
2427 dlci->constipated = true;
2428 } else {
2429 dlci->data = gsm_dlci_command;
2430 }
2431 gsm->dlci[addr] = dlci;
2432 return dlci;
2433}
2434
2435/**
2436 * gsm_dlci_free - free DLCI
2437 * @port: tty port for DLCI to free
2438 *
2439 * Free up a DLCI.
2440 *
2441 * Can sleep.
2442 */
2443static void gsm_dlci_free(struct tty_port *port)
2444{
2445 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2446
2447 timer_shutdown_sync(&dlci->t1);
2448 dlci->gsm->dlci[dlci->addr] = NULL;
2449 kfifo_free(&dlci->fifo);
2450 while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
2451 dev_kfree_skb(dlci->skb);
2452 kfree(dlci);
2453}
2454
2455static inline void dlci_get(struct gsm_dlci *dlci)
2456{
2457 tty_port_get(&dlci->port);
2458}
2459
2460static inline void dlci_put(struct gsm_dlci *dlci)
2461{
2462 tty_port_put(&dlci->port);
2463}
2464
2465static void gsm_destroy_network(struct gsm_dlci *dlci);
2466
2467/**
2468 * gsm_dlci_release - release DLCI
2469 * @dlci: DLCI to destroy
2470 *
2471 * Release a DLCI. Actual free is deferred until either
2472 * mux is closed or tty is closed - whichever is last.
2473 *
2474 * Can sleep.
2475 */
2476static void gsm_dlci_release(struct gsm_dlci *dlci)
2477{
2478 struct tty_struct *tty = tty_port_tty_get(&dlci->port);
2479 if (tty) {
2480 mutex_lock(&dlci->mutex);
2481 gsm_destroy_network(dlci);
2482 mutex_unlock(&dlci->mutex);
2483
2484 /* We cannot use tty_hangup() because in tty_kref_put() the tty
2485 * driver assumes that the hangup queue is free and reuses it to
2486 * queue release_one_tty() -> NULL pointer panic in
2487 * process_one_work().
2488 */
2489 tty_vhangup(tty);
2490
2491 tty_port_tty_set(&dlci->port, NULL);
2492 tty_kref_put(tty);
2493 }
2494 dlci->state = DLCI_CLOSED;
2495 dlci_put(dlci);
2496}
2497
2498/*
2499 * LAPBish link layer logic
2500 */
2501
2502/**
2503 * gsm_queue - a GSM frame is ready to process
2504 * @gsm: pointer to our gsm mux
2505 *
2506 * At this point in time a frame has arrived and been demangled from
2507 * the line encoding. All the differences between the encodings have
2508 * been handled below us and the frame is unpacked into the structures.
2509 * The fcs holds the header FCS but any data FCS must be added here.
2510 */
2511
2512static void gsm_queue(struct gsm_mux *gsm)
2513{
2514 struct gsm_dlci *dlci;
2515 u8 cr;
2516 int address;
2517
2518 if (gsm->fcs != GOOD_FCS) {
2519 gsm->bad_fcs++;
2520 if (debug & DBG_DATA)
2521 pr_debug("BAD FCS %02x\n", gsm->fcs);
2522 return;
2523 }
2524 address = gsm->address >> 1;
2525 if (address >= NUM_DLCI)
2526 goto invalid;
2527
2528 cr = gsm->address & 1; /* C/R bit */
2529 cr ^= gsm->initiator ? 0 : 1; /* Flip so 1 always means command */
2530
2531 gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
2532
2533 dlci = gsm->dlci[address];
2534
2535 switch (gsm->control) {
2536 case SABM|PF:
2537 if (cr == 1)
2538 goto invalid;
2539 if (dlci == NULL)
2540 dlci = gsm_dlci_alloc(gsm, address);
2541 if (dlci == NULL)
2542 return;
2543 if (dlci->dead)
2544 gsm_response(gsm, address, DM|PF);
2545 else {
2546 gsm_response(gsm, address, UA|PF);
2547 gsm_dlci_open(dlci);
2548 }
2549 break;
2550 case DISC|PF:
2551 if (cr == 1)
2552 goto invalid;
2553 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
2554 gsm_response(gsm, address, DM|PF);
2555 return;
2556 }
2557 /* Real close complete */
2558 gsm_response(gsm, address, UA|PF);
2559 gsm_dlci_close(dlci);
2560 break;
2561 case UA|PF:
2562 if (cr == 0 || dlci == NULL)
2563 break;
2564 switch (dlci->state) {
2565 case DLCI_CLOSING:
2566 gsm_dlci_close(dlci);
2567 break;
2568 case DLCI_OPENING:
2569 gsm_dlci_open(dlci);
2570 break;
2571 default:
2572 pr_debug("%s: unhandled state: %d\n", __func__,
2573 dlci->state);
2574 break;
2575 }
2576 break;
2577 case DM: /* DM can be valid unsolicited */
2578 case DM|PF:
2579 if (cr)
2580 goto invalid;
2581 if (dlci == NULL)
2582 return;
2583 gsm_dlci_close(dlci);
2584 break;
2585 case UI:
2586 case UI|PF:
2587 case UIH:
2588 case UIH|PF:
2589 if (dlci == NULL || dlci->state != DLCI_OPEN) {
2590 gsm_response(gsm, address, DM|PF);
2591 return;
2592 }
2593 dlci->data(dlci, gsm->buf, gsm->len);
2594 break;
2595 default:
2596 goto invalid;
2597 }
2598 return;
2599invalid:
2600 gsm->malformed++;
2601 return;
2602}
2603
2604
2605/**
2606 * gsm0_receive - perform processing for non-transparency
2607 * @gsm: gsm data for this ldisc instance
2608 * @c: character
2609 *
2610 * Receive bytes in gsm mode 0
2611 */
2612
2613static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
2614{
2615 unsigned int len;
2616
2617 switch (gsm->state) {
2618 case GSM_SEARCH: /* SOF marker */
2619 if (c == GSM0_SOF) {
2620 gsm->state = GSM_ADDRESS;
2621 gsm->address = 0;
2622 gsm->len = 0;
2623 gsm->fcs = INIT_FCS;
2624 }
2625 break;
2626 case GSM_ADDRESS: /* Address EA */
2627 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2628 if (gsm_read_ea(&gsm->address, c))
2629 gsm->state = GSM_CONTROL;
2630 break;
2631 case GSM_CONTROL: /* Control Byte */
2632 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2633 gsm->control = c;
2634 gsm->state = GSM_LEN0;
2635 break;
2636 case GSM_LEN0: /* Length EA */
2637 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2638 if (gsm_read_ea(&gsm->len, c)) {
2639 if (gsm->len > gsm->mru) {
2640 gsm->bad_size++;
2641 gsm->state = GSM_SEARCH;
2642 break;
2643 }
2644 gsm->count = 0;
2645 if (!gsm->len)
2646 gsm->state = GSM_FCS;
2647 else
2648 gsm->state = GSM_DATA;
2649 break;
2650 }
2651 gsm->state = GSM_LEN1;
2652 break;
2653 case GSM_LEN1:
2654 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2655 len = c;
2656 gsm->len |= len << 7;
2657 if (gsm->len > gsm->mru) {
2658 gsm->bad_size++;
2659 gsm->state = GSM_SEARCH;
2660 break;
2661 }
2662 gsm->count = 0;
2663 if (!gsm->len)
2664 gsm->state = GSM_FCS;
2665 else
2666 gsm->state = GSM_DATA;
2667 break;
2668 case GSM_DATA: /* Data */
2669 gsm->buf[gsm->count++] = c;
2670 if (gsm->count == gsm->len) {
2671 /* Calculate final FCS for UI frames over all data */
2672 if ((gsm->control & ~PF) != UIH) {
2673 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
2674 gsm->count);
2675 }
2676 gsm->state = GSM_FCS;
2677 }
2678 break;
2679 case GSM_FCS: /* FCS follows the packet */
2680 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2681 gsm->state = GSM_SSOF;
2682 break;
2683 case GSM_SSOF:
2684 gsm->state = GSM_SEARCH;
2685 if (c == GSM0_SOF)
2686 gsm_queue(gsm);
2687 else
2688 gsm->bad_size++;
2689 break;
2690 default:
2691 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2692 break;
2693 }
2694}
2695
2696/**
2697 * gsm1_receive - perform processing for non-transparency
2698 * @gsm: gsm data for this ldisc instance
2699 * @c: character
2700 *
2701 * Receive bytes in mode 1 (Advanced option)
2702 */
2703
2704static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
2705{
2706 /* handle XON/XOFF */
2707 if ((c & ISO_IEC_646_MASK) == XON) {
2708 gsm->constipated = true;
2709 return;
2710 } else if ((c & ISO_IEC_646_MASK) == XOFF) {
2711 gsm->constipated = false;
2712 /* Kick the link in case it is idling */
2713 gsmld_write_trigger(gsm);
2714 return;
2715 }
2716 if (c == GSM1_SOF) {
2717 /* EOF is only valid in frame if we have got to the data state */
2718 if (gsm->state == GSM_DATA) {
2719 if (gsm->count < 1) {
2720 /* Missing FSC */
2721 gsm->malformed++;
2722 gsm->state = GSM_START;
2723 return;
2724 }
2725 /* Remove the FCS from data */
2726 gsm->count--;
2727 if ((gsm->control & ~PF) != UIH) {
2728 /* Calculate final FCS for UI frames over all
2729 * data but FCS
2730 */
2731 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf,
2732 gsm->count);
2733 }
2734 /* Add the FCS itself to test against GOOD_FCS */
2735 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
2736 gsm->len = gsm->count;
2737 gsm_queue(gsm);
2738 gsm->state = GSM_START;
2739 return;
2740 }
2741 /* Any partial frame was a runt so go back to start */
2742 if (gsm->state != GSM_START) {
2743 if (gsm->state != GSM_SEARCH)
2744 gsm->malformed++;
2745 gsm->state = GSM_START;
2746 }
2747 /* A SOF in GSM_START means we are still reading idling or
2748 framing bytes */
2749 return;
2750 }
2751
2752 if (c == GSM1_ESCAPE) {
2753 gsm->escape = true;
2754 return;
2755 }
2756
2757 /* Only an unescaped SOF gets us out of GSM search */
2758 if (gsm->state == GSM_SEARCH)
2759 return;
2760
2761 if (gsm->escape) {
2762 c ^= GSM1_ESCAPE_BITS;
2763 gsm->escape = false;
2764 }
2765 switch (gsm->state) {
2766 case GSM_START: /* First byte after SOF */
2767 gsm->address = 0;
2768 gsm->state = GSM_ADDRESS;
2769 gsm->fcs = INIT_FCS;
2770 fallthrough;
2771 case GSM_ADDRESS: /* Address continuation */
2772 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2773 if (gsm_read_ea(&gsm->address, c))
2774 gsm->state = GSM_CONTROL;
2775 break;
2776 case GSM_CONTROL: /* Control Byte */
2777 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
2778 gsm->control = c;
2779 gsm->count = 0;
2780 gsm->state = GSM_DATA;
2781 break;
2782 case GSM_DATA: /* Data */
2783 if (gsm->count > gsm->mru) { /* Allow one for the FCS */
2784 gsm->state = GSM_OVERRUN;
2785 gsm->bad_size++;
2786 } else
2787 gsm->buf[gsm->count++] = c;
2788 break;
2789 case GSM_OVERRUN: /* Over-long - eg a dropped SOF */
2790 break;
2791 default:
2792 pr_debug("%s: unhandled state: %d\n", __func__, gsm->state);
2793 break;
2794 }
2795}
2796
2797/**
2798 * gsm_error - handle tty error
2799 * @gsm: ldisc data
2800 *
2801 * Handle an error in the receipt of data for a frame. Currently we just
2802 * go back to hunting for a SOF.
2803 *
2804 * FIXME: better diagnostics ?
2805 */
2806
2807static void gsm_error(struct gsm_mux *gsm)
2808{
2809 gsm->state = GSM_SEARCH;
2810 gsm->io_error++;
2811}
2812
2813/**
2814 * gsm_cleanup_mux - generic GSM protocol cleanup
2815 * @gsm: our mux
2816 * @disc: disconnect link?
2817 *
2818 * Clean up the bits of the mux which are the same for all framing
2819 * protocols. Remove the mux from the mux table, stop all the timers
2820 * and then shut down each device hanging up the channels as we go.
2821 */
2822
2823static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
2824{
2825 int i;
2826 struct gsm_dlci *dlci = gsm->dlci[0];
2827 struct gsm_msg *txq, *ntxq;
2828
2829 gsm->dead = true;
2830 mutex_lock(&gsm->mutex);
2831
2832 if (dlci) {
2833 if (disc && dlci->state != DLCI_CLOSED) {
2834 gsm_dlci_begin_close(dlci);
2835 wait_event(gsm->event, dlci->state == DLCI_CLOSED);
2836 }
2837 dlci->dead = true;
2838 }
2839
2840 /* Finish outstanding timers, making sure they are done */
2841 del_timer_sync(&gsm->kick_timer);
2842 del_timer_sync(&gsm->t2_timer);
2843
2844 /* Finish writing to ldisc */
2845 flush_work(&gsm->tx_work);
2846
2847 /* Free up any link layer users and finally the control channel */
2848 if (gsm->has_devices) {
2849 gsm_unregister_devices(gsm_tty_driver, gsm->num);
2850 gsm->has_devices = false;
2851 }
2852 for (i = NUM_DLCI - 1; i >= 0; i--)
2853 if (gsm->dlci[i])
2854 gsm_dlci_release(gsm->dlci[i]);
2855 mutex_unlock(&gsm->mutex);
2856 /* Now wipe the queues */
2857 tty_ldisc_flush(gsm->tty);
2858 list_for_each_entry_safe(txq, ntxq, &gsm->tx_ctrl_list, list)
2859 kfree(txq);
2860 INIT_LIST_HEAD(&gsm->tx_ctrl_list);
2861 list_for_each_entry_safe(txq, ntxq, &gsm->tx_data_list, list)
2862 kfree(txq);
2863 INIT_LIST_HEAD(&gsm->tx_data_list);
2864}
2865
2866/**
2867 * gsm_activate_mux - generic GSM setup
2868 * @gsm: our mux
2869 *
2870 * Set up the bits of the mux which are the same for all framing
2871 * protocols. Add the mux to the mux table so it can be opened and
2872 * finally kick off connecting to DLCI 0 on the modem.
2873 */
2874
2875static int gsm_activate_mux(struct gsm_mux *gsm)
2876{
2877 struct gsm_dlci *dlci;
2878 int ret;
2879
2880 dlci = gsm_dlci_alloc(gsm, 0);
2881 if (dlci == NULL)
2882 return -ENOMEM;
2883
2884 if (gsm->encoding == GSM_BASIC_OPT)
2885 gsm->receive = gsm0_receive;
2886 else
2887 gsm->receive = gsm1_receive;
2888
2889 ret = gsm_register_devices(gsm_tty_driver, gsm->num);
2890 if (ret)
2891 return ret;
2892
2893 gsm->has_devices = true;
2894 gsm->dead = false; /* Tty opens are now permissible */
2895 return 0;
2896}
2897
2898/**
2899 * gsm_free_mux - free up a mux
2900 * @gsm: mux to free
2901 *
2902 * Dispose of allocated resources for a dead mux
2903 */
2904static void gsm_free_mux(struct gsm_mux *gsm)
2905{
2906 int i;
2907
2908 for (i = 0; i < MAX_MUX; i++) {
2909 if (gsm == gsm_mux[i]) {
2910 gsm_mux[i] = NULL;
2911 break;
2912 }
2913 }
2914 mutex_destroy(&gsm->mutex);
2915 kfree(gsm->txframe);
2916 kfree(gsm->buf);
2917 kfree(gsm);
2918}
2919
2920/**
2921 * gsm_free_muxr - free up a mux
2922 * @ref: kreference to the mux to free
2923 *
2924 * Dispose of allocated resources for a dead mux
2925 */
2926static void gsm_free_muxr(struct kref *ref)
2927{
2928 struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2929 gsm_free_mux(gsm);
2930}
2931
2932static inline void mux_get(struct gsm_mux *gsm)
2933{
2934 unsigned long flags;
2935
2936 spin_lock_irqsave(&gsm_mux_lock, flags);
2937 kref_get(&gsm->ref);
2938 spin_unlock_irqrestore(&gsm_mux_lock, flags);
2939}
2940
2941static inline void mux_put(struct gsm_mux *gsm)
2942{
2943 unsigned long flags;
2944
2945 spin_lock_irqsave(&gsm_mux_lock, flags);
2946 kref_put(&gsm->ref, gsm_free_muxr);
2947 spin_unlock_irqrestore(&gsm_mux_lock, flags);
2948}
2949
2950static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
2951{
2952 return gsm->num * NUM_DLCI;
2953}
2954
2955static inline unsigned int mux_line_to_num(unsigned int line)
2956{
2957 return line / NUM_DLCI;
2958}
2959
2960/**
2961 * gsm_alloc_mux - allocate a mux
2962 *
2963 * Creates a new mux ready for activation.
2964 */
2965
2966static struct gsm_mux *gsm_alloc_mux(void)
2967{
2968 int i;
2969 struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2970 if (gsm == NULL)
2971 return NULL;
2972 gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2973 if (gsm->buf == NULL) {
2974 kfree(gsm);
2975 return NULL;
2976 }
2977 gsm->txframe = kmalloc(2 * (MAX_MTU + PROT_OVERHEAD - 1), GFP_KERNEL);
2978 if (gsm->txframe == NULL) {
2979 kfree(gsm->buf);
2980 kfree(gsm);
2981 return NULL;
2982 }
2983 spin_lock_init(&gsm->lock);
2984 mutex_init(&gsm->mutex);
2985 kref_init(&gsm->ref);
2986 INIT_LIST_HEAD(&gsm->tx_ctrl_list);
2987 INIT_LIST_HEAD(&gsm->tx_data_list);
2988 timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
2989 timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
2990 INIT_WORK(&gsm->tx_work, gsmld_write_task);
2991 init_waitqueue_head(&gsm->event);
2992 spin_lock_init(&gsm->control_lock);
2993 spin_lock_init(&gsm->tx_lock);
2994
2995 gsm->t1 = T1;
2996 gsm->t2 = T2;
2997 gsm->t3 = T3;
2998 gsm->n2 = N2;
2999 gsm->k = K;
3000 gsm->ftype = UIH;
3001 gsm->adaption = 1;
3002 gsm->encoding = GSM_ADV_OPT;
3003 gsm->mru = 64; /* Default to encoding 1 so these should be 64 */
3004 gsm->mtu = 64;
3005 gsm->dead = true; /* Avoid early tty opens */
3006
3007 /* Store the instance to the mux array or abort if no space is
3008 * available.
3009 */
3010 spin_lock(&gsm_mux_lock);
3011 for (i = 0; i < MAX_MUX; i++) {
3012 if (!gsm_mux[i]) {
3013 gsm_mux[i] = gsm;
3014 gsm->num = i;
3015 break;
3016 }
3017 }
3018 spin_unlock(&gsm_mux_lock);
3019 if (i == MAX_MUX) {
3020 mutex_destroy(&gsm->mutex);
3021 kfree(gsm->txframe);
3022 kfree(gsm->buf);
3023 kfree(gsm);
3024 return NULL;
3025 }
3026
3027 return gsm;
3028}
3029
3030static void gsm_copy_config_values(struct gsm_mux *gsm,
3031 struct gsm_config *c)
3032{
3033 memset(c, 0, sizeof(*c));
3034 c->adaption = gsm->adaption;
3035 c->encapsulation = gsm->encoding;
3036 c->initiator = gsm->initiator;
3037 c->t1 = gsm->t1;
3038 c->t2 = gsm->t2;
3039 c->t3 = gsm->t3;
3040 c->n2 = gsm->n2;
3041 if (gsm->ftype == UIH)
3042 c->i = 1;
3043 else
3044 c->i = 2;
3045 pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
3046 c->mru = gsm->mru;
3047 c->mtu = gsm->mtu;
3048 c->k = gsm->k;
3049}
3050
3051static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
3052{
3053 int ret = 0;
3054 int need_close = 0;
3055 int need_restart = 0;
3056
3057 /* Stuff we don't support yet - UI or I frame transport, windowing */
3058 if ((c->adaption != 1 && c->adaption != 2) || c->k)
3059 return -EOPNOTSUPP;
3060 /* Check the MRU/MTU range looks sane */
3061 if (c->mru < MIN_MTU || c->mtu < MIN_MTU)
3062 return -EINVAL;
3063 if (c->mru > MAX_MRU || c->mtu > MAX_MTU)
3064 return -EINVAL;
3065 if (c->t3 > MAX_T3)
3066 return -EINVAL;
3067 if (c->n2 > 255)
3068 return -EINVAL;
3069 if (c->encapsulation > 1) /* Basic, advanced, no I */
3070 return -EINVAL;
3071 if (c->initiator > 1)
3072 return -EINVAL;
3073 if (c->k > MAX_WINDOW_SIZE)
3074 return -EINVAL;
3075 if (c->i == 0 || c->i > 2) /* UIH and UI only */
3076 return -EINVAL;
3077 /*
3078 * See what is needed for reconfiguration
3079 */
3080
3081 /* Timing fields */
3082 if (c->t1 != 0 && c->t1 != gsm->t1)
3083 need_restart = 1;
3084 if (c->t2 != 0 && c->t2 != gsm->t2)
3085 need_restart = 1;
3086 if (c->encapsulation != gsm->encoding)
3087 need_restart = 1;
3088 if (c->adaption != gsm->adaption)
3089 need_restart = 1;
3090 /* Requires care */
3091 if (c->initiator != gsm->initiator)
3092 need_close = 1;
3093 if (c->mru != gsm->mru)
3094 need_restart = 1;
3095 if (c->mtu != gsm->mtu)
3096 need_restart = 1;
3097
3098 /*
3099 * Close down what is needed, restart and initiate the new
3100 * configuration. On the first time there is no DLCI[0]
3101 * and closing or cleaning up is not necessary.
3102 */
3103 if (need_close || need_restart)
3104 gsm_cleanup_mux(gsm, true);
3105
3106 gsm->initiator = c->initiator;
3107 gsm->mru = c->mru;
3108 gsm->mtu = c->mtu;
3109 gsm->encoding = c->encapsulation ? GSM_ADV_OPT : GSM_BASIC_OPT;
3110 gsm->adaption = c->adaption;
3111 gsm->n2 = c->n2;
3112
3113 if (c->i == 1)
3114 gsm->ftype = UIH;
3115 else if (c->i == 2)
3116 gsm->ftype = UI;
3117
3118 if (c->t1)
3119 gsm->t1 = c->t1;
3120 if (c->t2)
3121 gsm->t2 = c->t2;
3122 if (c->t3)
3123 gsm->t3 = c->t3;
3124 if (c->k)
3125 gsm->k = c->k;
3126
3127 /*
3128 * FIXME: We need to separate activation/deactivation from adding
3129 * and removing from the mux array
3130 */
3131 if (gsm->dead) {
3132 ret = gsm_activate_mux(gsm);
3133 if (ret)
3134 return ret;
3135 if (gsm->initiator)
3136 gsm_dlci_begin_open(gsm->dlci[0]);
3137 }
3138 return 0;
3139}
3140
3141/**
3142 * gsmld_output - write to link
3143 * @gsm: our mux
3144 * @data: bytes to output
3145 * @len: size
3146 *
3147 * Write a block of data from the GSM mux to the data channel. This
3148 * will eventually be serialized from above but at the moment isn't.
3149 */
3150
3151static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
3152{
3153 if (tty_write_room(gsm->tty) < len) {
3154 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
3155 return -ENOSPC;
3156 }
3157 if (debug & DBG_DATA)
3158 gsm_hex_dump_bytes(__func__, data, len);
3159 return gsm->tty->ops->write(gsm->tty, data, len);
3160}
3161
3162
3163/**
3164 * gsmld_write_trigger - schedule ldisc write task
3165 * @gsm: our mux
3166 */
3167static void gsmld_write_trigger(struct gsm_mux *gsm)
3168{
3169 if (!gsm || !gsm->dlci[0] || gsm->dlci[0]->dead)
3170 return;
3171 schedule_work(&gsm->tx_work);
3172}
3173
3174
3175/**
3176 * gsmld_write_task - ldisc write task
3177 * @work: our tx write work
3178 *
3179 * Writes out data to the ldisc if possible. We are doing this here to
3180 * avoid dead-locking. This returns if no space or data is left for output.
3181 */
3182static void gsmld_write_task(struct work_struct *work)
3183{
3184 struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work);
3185 unsigned long flags;
3186 int i, ret;
3187
3188 /* All outstanding control channel and control messages and one data
3189 * frame is sent.
3190 */
3191 ret = -ENODEV;
3192 spin_lock_irqsave(&gsm->tx_lock, flags);
3193 if (gsm->tty)
3194 ret = gsm_data_kick(gsm);
3195 spin_unlock_irqrestore(&gsm->tx_lock, flags);
3196
3197 if (ret >= 0)
3198 for (i = 0; i < NUM_DLCI; i++)
3199 if (gsm->dlci[i])
3200 tty_port_tty_wakeup(&gsm->dlci[i]->port);
3201}
3202
3203/**
3204 * gsmld_attach_gsm - mode set up
3205 * @tty: our tty structure
3206 * @gsm: our mux
3207 *
3208 * Set up the MUX for basic mode and commence connecting to the
3209 * modem. Currently called from the line discipline set up but
3210 * will need moving to an ioctl path.
3211 */
3212
3213static void gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
3214{
3215 gsm->tty = tty_kref_get(tty);
3216 /* Turn off tty XON/XOFF handling to handle it explicitly. */
3217 gsm->old_c_iflag = tty->termios.c_iflag;
3218 tty->termios.c_iflag &= (IXON | IXOFF);
3219}
3220
3221/**
3222 * gsmld_detach_gsm - stop doing 0710 mux
3223 * @tty: tty attached to the mux
3224 * @gsm: mux
3225 *
3226 * Shutdown and then clean up the resources used by the line discipline
3227 */
3228
3229static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
3230{
3231 WARN_ON(tty != gsm->tty);
3232 /* Restore tty XON/XOFF handling. */
3233 gsm->tty->termios.c_iflag = gsm->old_c_iflag;
3234 tty_kref_put(gsm->tty);
3235 gsm->tty = NULL;
3236}
3237
3238static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
3239 const char *fp, int count)
3240{
3241 struct gsm_mux *gsm = tty->disc_data;
3242 char flags = TTY_NORMAL;
3243
3244 if (debug & DBG_DATA)
3245 gsm_hex_dump_bytes(__func__, cp, count);
3246
3247 for (; count; count--, cp++) {
3248 if (fp)
3249 flags = *fp++;
3250 switch (flags) {
3251 case TTY_NORMAL:
3252 if (gsm->receive)
3253 gsm->receive(gsm, *cp);
3254 break;
3255 case TTY_OVERRUN:
3256 case TTY_BREAK:
3257 case TTY_PARITY:
3258 case TTY_FRAME:
3259 gsm_error(gsm);
3260 break;
3261 default:
3262 WARN_ONCE(1, "%s: unknown flag %d\n",
3263 tty_name(tty), flags);
3264 break;
3265 }
3266 }
3267 /* FASYNC if needed ? */
3268 /* If clogged call tty_throttle(tty); */
3269}
3270
3271/**
3272 * gsmld_flush_buffer - clean input queue
3273 * @tty: terminal device
3274 *
3275 * Flush the input buffer. Called when the line discipline is
3276 * being closed, when the tty layer wants the buffer flushed (eg
3277 * at hangup).
3278 */
3279
3280static void gsmld_flush_buffer(struct tty_struct *tty)
3281{
3282}
3283
3284/**
3285 * gsmld_close - close the ldisc for this tty
3286 * @tty: device
3287 *
3288 * Called from the terminal layer when this line discipline is
3289 * being shut down, either because of a close or becsuse of a
3290 * discipline change. The function will not be called while other
3291 * ldisc methods are in progress.
3292 */
3293
3294static void gsmld_close(struct tty_struct *tty)
3295{
3296 struct gsm_mux *gsm = tty->disc_data;
3297
3298 /* The ldisc locks and closes the port before calling our close. This
3299 * means we have no way to do a proper disconnect. We will not bother
3300 * to do one.
3301 */
3302 gsm_cleanup_mux(gsm, false);
3303
3304 gsmld_detach_gsm(tty, gsm);
3305
3306 gsmld_flush_buffer(tty);
3307 /* Do other clean up here */
3308 mux_put(gsm);
3309}
3310
3311/**
3312 * gsmld_open - open an ldisc
3313 * @tty: terminal to open
3314 *
3315 * Called when this line discipline is being attached to the
3316 * terminal device. Can sleep. Called serialized so that no
3317 * other events will occur in parallel. No further open will occur
3318 * until a close.
3319 */
3320
3321static int gsmld_open(struct tty_struct *tty)
3322{
3323 struct gsm_mux *gsm;
3324
3325 if (tty->ops->write == NULL)
3326 return -EINVAL;
3327
3328 /* Attach our ldisc data */
3329 gsm = gsm_alloc_mux();
3330 if (gsm == NULL)
3331 return -ENOMEM;
3332
3333 tty->disc_data = gsm;
3334 tty->receive_room = 65536;
3335
3336 /* Attach the initial passive connection */
3337 gsm->encoding = GSM_ADV_OPT;
3338 gsmld_attach_gsm(tty, gsm);
3339
3340 return 0;
3341}
3342
3343/**
3344 * gsmld_write_wakeup - asynchronous I/O notifier
3345 * @tty: tty device
3346 *
3347 * Required for the ptys, serial driver etc. since processes
3348 * that attach themselves to the master and rely on ASYNC
3349 * IO must be woken up
3350 */
3351
3352static void gsmld_write_wakeup(struct tty_struct *tty)
3353{
3354 struct gsm_mux *gsm = tty->disc_data;
3355
3356 /* Queue poll */
3357 gsmld_write_trigger(gsm);
3358}
3359
3360/**
3361 * gsmld_read - read function for tty
3362 * @tty: tty device
3363 * @file: file object
3364 * @buf: userspace buffer pointer
3365 * @nr: size of I/O
3366 * @cookie: unused
3367 * @offset: unused
3368 *
3369 * Perform reads for the line discipline. We are guaranteed that the
3370 * line discipline will not be closed under us but we may get multiple
3371 * parallel readers and must handle this ourselves. We may also get
3372 * a hangup. Always called in user context, may sleep.
3373 *
3374 * This code must be sure never to sleep through a hangup.
3375 */
3376
3377static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
3378 unsigned char *buf, size_t nr,
3379 void **cookie, unsigned long offset)
3380{
3381 return -EOPNOTSUPP;
3382}
3383
3384/**
3385 * gsmld_write - write function for tty
3386 * @tty: tty device
3387 * @file: file object
3388 * @buf: userspace buffer pointer
3389 * @nr: size of I/O
3390 *
3391 * Called when the owner of the device wants to send a frame
3392 * itself (or some other control data). The data is transferred
3393 * as-is and must be properly framed and checksummed as appropriate
3394 * by userspace. Frames are either sent whole or not at all as this
3395 * avoids pain user side.
3396 */
3397
3398static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
3399 const unsigned char *buf, size_t nr)
3400{
3401 struct gsm_mux *gsm = tty->disc_data;
3402 unsigned long flags;
3403 int space;
3404 int ret;
3405
3406 if (!gsm)
3407 return -ENODEV;
3408
3409 ret = -ENOBUFS;
3410 spin_lock_irqsave(&gsm->tx_lock, flags);
3411 space = tty_write_room(tty);
3412 if (space >= nr)
3413 ret = tty->ops->write(tty, buf, nr);
3414 else
3415 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
3416 spin_unlock_irqrestore(&gsm->tx_lock, flags);
3417
3418 return ret;
3419}
3420
3421/**
3422 * gsmld_poll - poll method for N_GSM0710
3423 * @tty: terminal device
3424 * @file: file accessing it
3425 * @wait: poll table
3426 *
3427 * Called when the line discipline is asked to poll() for data or
3428 * for special events. This code is not serialized with respect to
3429 * other events save open/close.
3430 *
3431 * This code must be sure never to sleep through a hangup.
3432 * Called without the kernel lock held - fine
3433 */
3434
3435static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
3436 poll_table *wait)
3437{
3438 __poll_t mask = 0;
3439 struct gsm_mux *gsm = tty->disc_data;
3440
3441 poll_wait(file, &tty->read_wait, wait);
3442 poll_wait(file, &tty->write_wait, wait);
3443
3444 if (gsm->dead)
3445 mask |= EPOLLHUP;
3446 if (tty_hung_up_p(file))
3447 mask |= EPOLLHUP;
3448 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
3449 mask |= EPOLLHUP;
3450 if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
3451 mask |= EPOLLOUT | EPOLLWRNORM;
3452 return mask;
3453}
3454
3455static int gsmld_ioctl(struct tty_struct *tty, unsigned int cmd,
3456 unsigned long arg)
3457{
3458 struct gsm_config c;
3459 struct gsm_mux *gsm = tty->disc_data;
3460 unsigned int base;
3461
3462 switch (cmd) {
3463 case GSMIOC_GETCONF:
3464 gsm_copy_config_values(gsm, &c);
3465 if (copy_to_user((void __user *)arg, &c, sizeof(c)))
3466 return -EFAULT;
3467 return 0;
3468 case GSMIOC_SETCONF:
3469 if (copy_from_user(&c, (void __user *)arg, sizeof(c)))
3470 return -EFAULT;
3471 return gsm_config(gsm, &c);
3472 case GSMIOC_GETFIRST:
3473 base = mux_num_to_base(gsm);
3474 return put_user(base + 1, (__u32 __user *)arg);
3475 default:
3476 return n_tty_ioctl_helper(tty, cmd, arg);
3477 }
3478}
3479
3480/*
3481 * Network interface
3482 *
3483 */
3484
3485static int gsm_mux_net_open(struct net_device *net)
3486{
3487 pr_debug("%s called\n", __func__);
3488 netif_start_queue(net);
3489 return 0;
3490}
3491
3492static int gsm_mux_net_close(struct net_device *net)
3493{
3494 netif_stop_queue(net);
3495 return 0;
3496}
3497
3498static void dlci_net_free(struct gsm_dlci *dlci)
3499{
3500 if (!dlci->net) {
3501 WARN_ON(1);
3502 return;
3503 }
3504 dlci->adaption = dlci->prev_adaption;
3505 dlci->data = dlci->prev_data;
3506 free_netdev(dlci->net);
3507 dlci->net = NULL;
3508}
3509static void net_free(struct kref *ref)
3510{
3511 struct gsm_mux_net *mux_net;
3512 struct gsm_dlci *dlci;
3513
3514 mux_net = container_of(ref, struct gsm_mux_net, ref);
3515 dlci = mux_net->dlci;
3516
3517 if (dlci->net) {
3518 unregister_netdev(dlci->net);
3519 dlci_net_free(dlci);
3520 }
3521}
3522
3523static inline void muxnet_get(struct gsm_mux_net *mux_net)
3524{
3525 kref_get(&mux_net->ref);
3526}
3527
3528static inline void muxnet_put(struct gsm_mux_net *mux_net)
3529{
3530 kref_put(&mux_net->ref, net_free);
3531}
3532
3533static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
3534 struct net_device *net)
3535{
3536 struct gsm_mux_net *mux_net = netdev_priv(net);
3537 struct gsm_dlci *dlci = mux_net->dlci;
3538 muxnet_get(mux_net);
3539
3540 skb_queue_head(&dlci->skb_list, skb);
3541 net->stats.tx_packets++;
3542 net->stats.tx_bytes += skb->len;
3543 gsm_dlci_data_kick(dlci);
3544 /* And tell the kernel when the last transmit started. */
3545 netif_trans_update(net);
3546 muxnet_put(mux_net);
3547 return NETDEV_TX_OK;
3548}
3549
3550/* called when a packet did not ack after watchdogtimeout */
3551static void gsm_mux_net_tx_timeout(struct net_device *net, unsigned int txqueue)
3552{
3553 /* Tell syslog we are hosed. */
3554 dev_dbg(&net->dev, "Tx timed out.\n");
3555
3556 /* Update statistics */
3557 net->stats.tx_errors++;
3558}
3559
3560static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
3561 const unsigned char *in_buf, int size)
3562{
3563 struct net_device *net = dlci->net;
3564 struct sk_buff *skb;
3565 struct gsm_mux_net *mux_net = netdev_priv(net);
3566 muxnet_get(mux_net);
3567
3568 /* Allocate an sk_buff */
3569 skb = dev_alloc_skb(size + NET_IP_ALIGN);
3570 if (!skb) {
3571 /* We got no receive buffer. */
3572 net->stats.rx_dropped++;
3573 muxnet_put(mux_net);
3574 return;
3575 }
3576 skb_reserve(skb, NET_IP_ALIGN);
3577 skb_put_data(skb, in_buf, size);
3578
3579 skb->dev = net;
3580 skb->protocol = htons(ETH_P_IP);
3581
3582 /* Ship it off to the kernel */
3583 netif_rx(skb);
3584
3585 /* update out statistics */
3586 net->stats.rx_packets++;
3587 net->stats.rx_bytes += size;
3588 muxnet_put(mux_net);
3589 return;
3590}
3591
3592static void gsm_mux_net_init(struct net_device *net)
3593{
3594 static const struct net_device_ops gsm_netdev_ops = {
3595 .ndo_open = gsm_mux_net_open,
3596 .ndo_stop = gsm_mux_net_close,
3597 .ndo_start_xmit = gsm_mux_net_start_xmit,
3598 .ndo_tx_timeout = gsm_mux_net_tx_timeout,
3599 };
3600
3601 net->netdev_ops = &gsm_netdev_ops;
3602
3603 /* fill in the other fields */
3604 net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
3605 net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
3606 net->type = ARPHRD_NONE;
3607 net->tx_queue_len = 10;
3608}
3609
3610
3611/* caller holds the dlci mutex */
3612static void gsm_destroy_network(struct gsm_dlci *dlci)
3613{
3614 struct gsm_mux_net *mux_net;
3615
3616 pr_debug("destroy network interface\n");
3617 if (!dlci->net)
3618 return;
3619 mux_net = netdev_priv(dlci->net);
3620 muxnet_put(mux_net);
3621}
3622
3623
3624/* caller holds the dlci mutex */
3625static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
3626{
3627 char *netname;
3628 int retval = 0;
3629 struct net_device *net;
3630 struct gsm_mux_net *mux_net;
3631
3632 if (!capable(CAP_NET_ADMIN))
3633 return -EPERM;
3634
3635 /* Already in a non tty mode */
3636 if (dlci->adaption > 2)
3637 return -EBUSY;
3638
3639 if (nc->protocol != htons(ETH_P_IP))
3640 return -EPROTONOSUPPORT;
3641
3642 if (nc->adaption != 3 && nc->adaption != 4)
3643 return -EPROTONOSUPPORT;
3644
3645 pr_debug("create network interface\n");
3646
3647 netname = "gsm%d";
3648 if (nc->if_name[0] != '\0')
3649 netname = nc->if_name;
3650 net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
3651 NET_NAME_UNKNOWN, gsm_mux_net_init);
3652 if (!net) {
3653 pr_err("alloc_netdev failed\n");
3654 return -ENOMEM;
3655 }
3656 net->mtu = dlci->mtu;
3657 net->min_mtu = MIN_MTU;
3658 net->max_mtu = dlci->mtu;
3659 mux_net = netdev_priv(net);
3660 mux_net->dlci = dlci;
3661 kref_init(&mux_net->ref);
3662 strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
3663
3664 /* reconfigure dlci for network */
3665 dlci->prev_adaption = dlci->adaption;
3666 dlci->prev_data = dlci->data;
3667 dlci->adaption = nc->adaption;
3668 dlci->data = gsm_mux_rx_netchar;
3669 dlci->net = net;
3670
3671 pr_debug("register netdev\n");
3672 retval = register_netdev(net);
3673 if (retval) {
3674 pr_err("network register fail %d\n", retval);
3675 dlci_net_free(dlci);
3676 return retval;
3677 }
3678 return net->ifindex; /* return network index */
3679}
3680
3681/* Line discipline for real tty */
3682static struct tty_ldisc_ops tty_ldisc_packet = {
3683 .owner = THIS_MODULE,
3684 .num = N_GSM0710,
3685 .name = "n_gsm",
3686 .open = gsmld_open,
3687 .close = gsmld_close,
3688 .flush_buffer = gsmld_flush_buffer,
3689 .read = gsmld_read,
3690 .write = gsmld_write,
3691 .ioctl = gsmld_ioctl,
3692 .poll = gsmld_poll,
3693 .receive_buf = gsmld_receive_buf,
3694 .write_wakeup = gsmld_write_wakeup
3695};
3696
3697/*
3698 * Virtual tty side
3699 */
3700
3701/**
3702 * gsm_modem_upd_via_data - send modem bits via convergence layer
3703 * @dlci: channel
3704 * @brk: break signal
3705 *
3706 * Send an empty frame to signal mobile state changes and to transmit the
3707 * break signal for adaption 2.
3708 */
3709
3710static void gsm_modem_upd_via_data(struct gsm_dlci *dlci, u8 brk)
3711{
3712 struct gsm_mux *gsm = dlci->gsm;
3713 unsigned long flags;
3714
3715 if (dlci->state != DLCI_OPEN || dlci->adaption != 2)
3716 return;
3717
3718 spin_lock_irqsave(&gsm->tx_lock, flags);
3719 gsm_dlci_modem_output(gsm, dlci, brk);
3720 spin_unlock_irqrestore(&gsm->tx_lock, flags);
3721}
3722
3723/**
3724 * gsm_modem_upd_via_msc - send modem bits via control frame
3725 * @dlci: channel
3726 * @brk: break signal
3727 */
3728
3729static int gsm_modem_upd_via_msc(struct gsm_dlci *dlci, u8 brk)
3730{
3731 u8 modembits[3];
3732 struct gsm_control *ctrl;
3733 int len = 2;
3734
3735 if (dlci->gsm->encoding != GSM_BASIC_OPT)
3736 return 0;
3737
3738 modembits[0] = (dlci->addr << 2) | 2 | EA; /* DLCI, Valid, EA */
3739 if (!brk) {
3740 modembits[1] = (gsm_encode_modem(dlci) << 1) | EA;
3741 } else {
3742 modembits[1] = gsm_encode_modem(dlci) << 1;
3743 modembits[2] = (brk << 4) | 2 | EA; /* Length, Break, EA */
3744 len++;
3745 }
3746 ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len);
3747 if (ctrl == NULL)
3748 return -ENOMEM;
3749 return gsm_control_wait(dlci->gsm, ctrl);
3750}
3751
3752/**
3753 * gsm_modem_update - send modem status line state
3754 * @dlci: channel
3755 * @brk: break signal
3756 */
3757
3758static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk)
3759{
3760 if (dlci->adaption == 2) {
3761 /* Send convergence layer type 2 empty data frame. */
3762 gsm_modem_upd_via_data(dlci, brk);
3763 return 0;
3764 } else if (dlci->gsm->encoding == GSM_BASIC_OPT) {
3765 /* Send as MSC control message. */
3766 return gsm_modem_upd_via_msc(dlci, brk);
3767 }
3768
3769 /* Modem status lines are not supported. */
3770 return -EPROTONOSUPPORT;
3771}
3772
3773static int gsm_carrier_raised(struct tty_port *port)
3774{
3775 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
3776 struct gsm_mux *gsm = dlci->gsm;
3777
3778 /* Not yet open so no carrier info */
3779 if (dlci->state != DLCI_OPEN)
3780 return 0;
3781 if (debug & DBG_CD_ON)
3782 return 1;
3783
3784 /*
3785 * Basic mode with control channel in ADM mode may not respond
3786 * to CMD_MSC at all and modem_rx is empty.
3787 */
3788 if (gsm->encoding == GSM_BASIC_OPT &&
3789 gsm->dlci[0]->mode == DLCI_MODE_ADM && !dlci->modem_rx)
3790 return 1;
3791
3792 return dlci->modem_rx & TIOCM_CD;
3793}
3794
3795static void gsm_dtr_rts(struct tty_port *port, int onoff)
3796{
3797 struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
3798 unsigned int modem_tx = dlci->modem_tx;
3799 if (onoff)
3800 modem_tx |= TIOCM_DTR | TIOCM_RTS;
3801 else
3802 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
3803 if (modem_tx != dlci->modem_tx) {
3804 dlci->modem_tx = modem_tx;
3805 gsm_modem_update(dlci, 0);
3806 }
3807}
3808
3809static const struct tty_port_operations gsm_port_ops = {
3810 .carrier_raised = gsm_carrier_raised,
3811 .dtr_rts = gsm_dtr_rts,
3812 .destruct = gsm_dlci_free,
3813};
3814
3815static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
3816{
3817 struct gsm_mux *gsm;
3818 struct gsm_dlci *dlci;
3819 unsigned int line = tty->index;
3820 unsigned int mux = mux_line_to_num(line);
3821 bool alloc = false;
3822 int ret;
3823
3824 line = line & 0x3F;
3825
3826 if (mux >= MAX_MUX)
3827 return -ENXIO;
3828 /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
3829 if (gsm_mux[mux] == NULL)
3830 return -EUNATCH;
3831 if (line == 0 || line > 61) /* 62/63 reserved */
3832 return -ECHRNG;
3833 gsm = gsm_mux[mux];
3834 if (gsm->dead)
3835 return -EL2HLT;
3836 /* If DLCI 0 is not yet fully open return an error.
3837 This is ok from a locking
3838 perspective as we don't have to worry about this
3839 if DLCI0 is lost */
3840 mutex_lock(&gsm->mutex);
3841 if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
3842 mutex_unlock(&gsm->mutex);
3843 return -EL2NSYNC;
3844 }
3845 dlci = gsm->dlci[line];
3846 if (dlci == NULL) {
3847 alloc = true;
3848 dlci = gsm_dlci_alloc(gsm, line);
3849 }
3850 if (dlci == NULL) {
3851 mutex_unlock(&gsm->mutex);
3852 return -ENOMEM;
3853 }
3854 ret = tty_port_install(&dlci->port, driver, tty);
3855 if (ret) {
3856 if (alloc)
3857 dlci_put(dlci);
3858 mutex_unlock(&gsm->mutex);
3859 return ret;
3860 }
3861
3862 dlci_get(dlci);
3863 dlci_get(gsm->dlci[0]);
3864 mux_get(gsm);
3865 tty->driver_data = dlci;
3866 mutex_unlock(&gsm->mutex);
3867
3868 return 0;
3869}
3870
3871static int gsmtty_open(struct tty_struct *tty, struct file *filp)
3872{
3873 struct gsm_dlci *dlci = tty->driver_data;
3874 struct tty_port *port = &dlci->port;
3875 struct gsm_mux *gsm = dlci->gsm;
3876
3877 port->count++;
3878 tty_port_tty_set(port, tty);
3879
3880 dlci->modem_rx = 0;
3881 /* We could in theory open and close before we wait - eg if we get
3882 a DM straight back. This is ok as that will have caused a hangup */
3883 tty_port_set_initialized(port, 1);
3884 /* Start sending off SABM messages */
3885 if (gsm->initiator)
3886 gsm_dlci_begin_open(dlci);
3887 else
3888 gsm_dlci_set_opening(dlci);
3889 /* And wait for virtual carrier */
3890 return tty_port_block_til_ready(port, tty, filp);
3891}
3892
3893static void gsmtty_close(struct tty_struct *tty, struct file *filp)
3894{
3895 struct gsm_dlci *dlci = tty->driver_data;
3896
3897 if (dlci == NULL)
3898 return;
3899 if (dlci->state == DLCI_CLOSED)
3900 return;
3901 mutex_lock(&dlci->mutex);
3902 gsm_destroy_network(dlci);
3903 mutex_unlock(&dlci->mutex);
3904 if (tty_port_close_start(&dlci->port, tty, filp) == 0)
3905 return;
3906 gsm_dlci_begin_close(dlci);
3907 if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
3908 tty_port_lower_dtr_rts(&dlci->port);
3909 tty_port_close_end(&dlci->port, tty);
3910 tty_port_tty_set(&dlci->port, NULL);
3911 return;
3912}
3913
3914static void gsmtty_hangup(struct tty_struct *tty)
3915{
3916 struct gsm_dlci *dlci = tty->driver_data;
3917 if (dlci->state == DLCI_CLOSED)
3918 return;
3919 tty_port_hangup(&dlci->port);
3920 gsm_dlci_begin_close(dlci);
3921}
3922
3923static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
3924 int len)
3925{
3926 int sent;
3927 struct gsm_dlci *dlci = tty->driver_data;
3928 if (dlci->state == DLCI_CLOSED)
3929 return -EINVAL;
3930 /* Stuff the bytes into the fifo queue */
3931 sent = kfifo_in_locked(&dlci->fifo, buf, len, &dlci->lock);
3932 /* Need to kick the channel */
3933 gsm_dlci_data_kick(dlci);
3934 return sent;
3935}
3936
3937static unsigned int gsmtty_write_room(struct tty_struct *tty)
3938{
3939 struct gsm_dlci *dlci = tty->driver_data;
3940 if (dlci->state == DLCI_CLOSED)
3941 return 0;
3942 return kfifo_avail(&dlci->fifo);
3943}
3944
3945static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty)
3946{
3947 struct gsm_dlci *dlci = tty->driver_data;
3948 if (dlci->state == DLCI_CLOSED)
3949 return 0;
3950 return kfifo_len(&dlci->fifo);
3951}
3952
3953static void gsmtty_flush_buffer(struct tty_struct *tty)
3954{
3955 struct gsm_dlci *dlci = tty->driver_data;
3956 unsigned long flags;
3957
3958 if (dlci->state == DLCI_CLOSED)
3959 return;
3960 /* Caution needed: If we implement reliable transport classes
3961 then the data being transmitted can't simply be junked once
3962 it has first hit the stack. Until then we can just blow it
3963 away */
3964 spin_lock_irqsave(&dlci->lock, flags);
3965 kfifo_reset(&dlci->fifo);
3966 spin_unlock_irqrestore(&dlci->lock, flags);
3967 /* Need to unhook this DLCI from the transmit queue logic */
3968}
3969
3970static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3971{
3972 /* The FIFO handles the queue so the kernel will do the right
3973 thing waiting on chars_in_buffer before calling us. No work
3974 to do here */
3975}
3976
3977static int gsmtty_tiocmget(struct tty_struct *tty)
3978{
3979 struct gsm_dlci *dlci = tty->driver_data;
3980 if (dlci->state == DLCI_CLOSED)
3981 return -EINVAL;
3982 return dlci->modem_rx;
3983}
3984
3985static int gsmtty_tiocmset(struct tty_struct *tty,
3986 unsigned int set, unsigned int clear)
3987{
3988 struct gsm_dlci *dlci = tty->driver_data;
3989 unsigned int modem_tx = dlci->modem_tx;
3990
3991 if (dlci->state == DLCI_CLOSED)
3992 return -EINVAL;
3993 modem_tx &= ~clear;
3994 modem_tx |= set;
3995
3996 if (modem_tx != dlci->modem_tx) {
3997 dlci->modem_tx = modem_tx;
3998 return gsm_modem_update(dlci, 0);
3999 }
4000 return 0;
4001}
4002
4003
4004static int gsmtty_ioctl(struct tty_struct *tty,
4005 unsigned int cmd, unsigned long arg)
4006{
4007 struct gsm_dlci *dlci = tty->driver_data;
4008 struct gsm_netconfig nc;
4009 int index;
4010
4011 if (dlci->state == DLCI_CLOSED)
4012 return -EINVAL;
4013 switch (cmd) {
4014 case GSMIOC_ENABLE_NET:
4015 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
4016 return -EFAULT;
4017 nc.if_name[IFNAMSIZ-1] = '\0';
4018 /* return net interface index or error code */
4019 mutex_lock(&dlci->mutex);
4020 index = gsm_create_network(dlci, &nc);
4021 mutex_unlock(&dlci->mutex);
4022 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
4023 return -EFAULT;
4024 return index;
4025 case GSMIOC_DISABLE_NET:
4026 if (!capable(CAP_NET_ADMIN))
4027 return -EPERM;
4028 mutex_lock(&dlci->mutex);
4029 gsm_destroy_network(dlci);
4030 mutex_unlock(&dlci->mutex);
4031 return 0;
4032 default:
4033 return -ENOIOCTLCMD;
4034 }
4035}
4036
4037static void gsmtty_set_termios(struct tty_struct *tty,
4038 const struct ktermios *old)
4039{
4040 struct gsm_dlci *dlci = tty->driver_data;
4041 if (dlci->state == DLCI_CLOSED)
4042 return;
4043 /* For the moment its fixed. In actual fact the speed information
4044 for the virtual channel can be propogated in both directions by
4045 the RPN control message. This however rapidly gets nasty as we
4046 then have to remap modem signals each way according to whether
4047 our virtual cable is null modem etc .. */
4048 tty_termios_copy_hw(&tty->termios, old);
4049}
4050
4051static void gsmtty_throttle(struct tty_struct *tty)
4052{
4053 struct gsm_dlci *dlci = tty->driver_data;
4054 if (dlci->state == DLCI_CLOSED)
4055 return;
4056 if (C_CRTSCTS(tty))
4057 dlci->modem_tx &= ~TIOCM_RTS;
4058 dlci->throttled = true;
4059 /* Send an MSC with RTS cleared */
4060 gsm_modem_update(dlci, 0);
4061}
4062
4063static void gsmtty_unthrottle(struct tty_struct *tty)
4064{
4065 struct gsm_dlci *dlci = tty->driver_data;
4066 if (dlci->state == DLCI_CLOSED)
4067 return;
4068 if (C_CRTSCTS(tty))
4069 dlci->modem_tx |= TIOCM_RTS;
4070 dlci->throttled = false;
4071 /* Send an MSC with RTS set */
4072 gsm_modem_update(dlci, 0);
4073}
4074
4075static int gsmtty_break_ctl(struct tty_struct *tty, int state)
4076{
4077 struct gsm_dlci *dlci = tty->driver_data;
4078 int encode = 0; /* Off */
4079 if (dlci->state == DLCI_CLOSED)
4080 return -EINVAL;
4081
4082 if (state == -1) /* "On indefinitely" - we can't encode this
4083 properly */
4084 encode = 0x0F;
4085 else if (state > 0) {
4086 encode = state / 200; /* mS to encoding */
4087 if (encode > 0x0F)
4088 encode = 0x0F; /* Best effort */
4089 }
4090 return gsm_modem_update(dlci, encode);
4091}
4092
4093static void gsmtty_cleanup(struct tty_struct *tty)
4094{
4095 struct gsm_dlci *dlci = tty->driver_data;
4096 struct gsm_mux *gsm = dlci->gsm;
4097
4098 dlci_put(dlci);
4099 dlci_put(gsm->dlci[0]);
4100 mux_put(gsm);
4101}
4102
4103/* Virtual ttys for the demux */
4104static const struct tty_operations gsmtty_ops = {
4105 .install = gsmtty_install,
4106 .open = gsmtty_open,
4107 .close = gsmtty_close,
4108 .write = gsmtty_write,
4109 .write_room = gsmtty_write_room,
4110 .chars_in_buffer = gsmtty_chars_in_buffer,
4111 .flush_buffer = gsmtty_flush_buffer,
4112 .ioctl = gsmtty_ioctl,
4113 .throttle = gsmtty_throttle,
4114 .unthrottle = gsmtty_unthrottle,
4115 .set_termios = gsmtty_set_termios,
4116 .hangup = gsmtty_hangup,
4117 .wait_until_sent = gsmtty_wait_until_sent,
4118 .tiocmget = gsmtty_tiocmget,
4119 .tiocmset = gsmtty_tiocmset,
4120 .break_ctl = gsmtty_break_ctl,
4121 .cleanup = gsmtty_cleanup,
4122};
4123
4124
4125
4126static int __init gsm_init(void)
4127{
4128 /* Fill in our line protocol discipline, and register it */
4129 int status = tty_register_ldisc(&tty_ldisc_packet);
4130 if (status != 0) {
4131 pr_err("n_gsm: can't register line discipline (err = %d)\n",
4132 status);
4133 return status;
4134 }
4135
4136 gsm_tty_driver = tty_alloc_driver(GSM_TTY_MINORS, TTY_DRIVER_REAL_RAW |
4137 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_HARDWARE_BREAK);
4138 if (IS_ERR(gsm_tty_driver)) {
4139 pr_err("gsm_init: tty allocation failed.\n");
4140 status = PTR_ERR(gsm_tty_driver);
4141 goto err_unreg_ldisc;
4142 }
4143 gsm_tty_driver->driver_name = "gsmtty";
4144 gsm_tty_driver->name = "gsmtty";
4145 gsm_tty_driver->major = 0; /* Dynamic */
4146 gsm_tty_driver->minor_start = 0;
4147 gsm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
4148 gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
4149 gsm_tty_driver->init_termios = tty_std_termios;
4150 /* Fixme */
4151 gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
4152 tty_set_operations(gsm_tty_driver, &gsmtty_ops);
4153
4154 if (tty_register_driver(gsm_tty_driver)) {
4155 pr_err("gsm_init: tty registration failed.\n");
4156 status = -EBUSY;
4157 goto err_put_driver;
4158 }
4159 pr_debug("gsm_init: loaded as %d,%d.\n",
4160 gsm_tty_driver->major, gsm_tty_driver->minor_start);
4161 return 0;
4162err_put_driver:
4163 tty_driver_kref_put(gsm_tty_driver);
4164err_unreg_ldisc:
4165 tty_unregister_ldisc(&tty_ldisc_packet);
4166 return status;
4167}
4168
4169static void __exit gsm_exit(void)
4170{
4171 tty_unregister_ldisc(&tty_ldisc_packet);
4172 tty_unregister_driver(gsm_tty_driver);
4173 tty_driver_kref_put(gsm_tty_driver);
4174}
4175
4176module_init(gsm_init);
4177module_exit(gsm_exit);
4178
4179
4180MODULE_LICENSE("GPL");
4181MODULE_ALIAS_LDISC(N_GSM0710);