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