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