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

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source code of linux/drivers/tty/n_gsm.c