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