1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * shdlc Link Layer Control
4 *
5 * Copyright (C) 2012 Intel Corporation. All rights reserved.
6 */
7
8 #define pr_fmt(fmt) "shdlc: %s: " fmt, __func__
9
10 #include <linux/types.h>
11 #include <linux/sched.h>
12 #include <linux/wait.h>
13 #include <linux/slab.h>
14 #include <linux/skbuff.h>
15
16 #include "llc.h"
17
18 enum shdlc_state {
19 SHDLC_DISCONNECTED = 0,
20 SHDLC_CONNECTING = 1,
21 SHDLC_NEGOTIATING = 2,
22 SHDLC_HALF_CONNECTED = 3,
23 SHDLC_CONNECTED = 4
24 };
25
26 struct llc_shdlc {
27 struct nfc_hci_dev *hdev;
28 xmit_to_drv_t xmit_to_drv;
29 rcv_to_hci_t rcv_to_hci;
30
31 struct mutex state_mutex;
32 enum shdlc_state state;
33 int hard_fault;
34
35 wait_queue_head_t *connect_wq;
36 int connect_tries;
37 int connect_result;
38 struct timer_list connect_timer;/* aka T3 in spec 10.6.1 */
39
40 u8 w; /* window size */
41 bool srej_support;
42
43 struct timer_list t1_timer; /* send ack timeout */
44 bool t1_active;
45
46 struct timer_list t2_timer; /* guard/retransmit timeout */
47 bool t2_active;
48
49 int ns; /* next seq num for send */
50 int nr; /* next expected seq num for receive */
51 int dnr; /* oldest sent unacked seq num */
52
53 struct sk_buff_head rcv_q;
54
55 struct sk_buff_head send_q;
56 bool rnr; /* other side is not ready to receive */
57
58 struct sk_buff_head ack_pending_q;
59
60 struct work_struct sm_work;
61
62 int tx_headroom;
63 int tx_tailroom;
64
65 llc_failure_t llc_failure;
66 };
67
68 #define SHDLC_LLC_HEAD_ROOM 2
69
70 #define SHDLC_MAX_WINDOW 4
71 #define SHDLC_SREJ_SUPPORT false
72
73 #define SHDLC_CONTROL_HEAD_MASK 0xe0
74 #define SHDLC_CONTROL_HEAD_I 0x80
75 #define SHDLC_CONTROL_HEAD_I2 0xa0
76 #define SHDLC_CONTROL_HEAD_S 0xc0
77 #define SHDLC_CONTROL_HEAD_U 0xe0
78
79 #define SHDLC_CONTROL_NS_MASK 0x38
80 #define SHDLC_CONTROL_NR_MASK 0x07
81 #define SHDLC_CONTROL_TYPE_MASK 0x18
82
83 #define SHDLC_CONTROL_M_MASK 0x1f
84
85 enum sframe_type {
86 S_FRAME_RR = 0x00,
87 S_FRAME_REJ = 0x01,
88 S_FRAME_RNR = 0x02,
89 S_FRAME_SREJ = 0x03
90 };
91
92 enum uframe_modifier {
93 U_FRAME_UA = 0x06,
94 U_FRAME_RSET = 0x19
95 };
96
97 #define SHDLC_CONNECT_VALUE_MS 5
98 #define SHDLC_T1_VALUE_MS(w) ((5 * w) / 4)
99 #define SHDLC_T2_VALUE_MS 300
100
101 #define SHDLC_DUMP_SKB(info, skb) \
102 do { \
103 pr_debug("%s:\n", info); \
104 print_hex_dump(KERN_DEBUG, "shdlc: ", DUMP_PREFIX_OFFSET, \
105 16, 1, skb->data, skb->len, 0); \
106 } while (0)
107
108 /* checks x < y <= z modulo 8 */
109 static bool llc_shdlc_x_lt_y_lteq_z(int x, int y, int z)
110 {
111 if (x < z)
112 return ((x < y) && (y <= z)) ? true : false;
113 else
114 return ((y > x) || (y <= z)) ? true : false;
115 }
116
117 /* checks x <= y < z modulo 8 */
118 static bool llc_shdlc_x_lteq_y_lt_z(int x, int y, int z)
119 {
120 if (x <= z)
121 return ((x <= y) && (y < z)) ? true : false;
122 else /* x > z -> z+8 > x */
123 return ((y >= x) || (y < z)) ? true : false;
124 }
125
126 static struct sk_buff *llc_shdlc_alloc_skb(const struct llc_shdlc *shdlc,
127 int payload_len)
128 {
129 struct sk_buff *skb;
130
131 skb = alloc_skb(shdlc->tx_headroom + SHDLC_LLC_HEAD_ROOM +
132 shdlc->tx_tailroom + payload_len, GFP_KERNEL);
133 if (skb)
134 skb_reserve(skb, shdlc->tx_headroom + SHDLC_LLC_HEAD_ROOM);
135
136 return skb;
137 }
138
139 /* immediately sends an S frame. */
140 static int llc_shdlc_send_s_frame(const struct llc_shdlc *shdlc,
141 enum sframe_type sframe_type, int nr)
142 {
143 int r;
144 struct sk_buff *skb;
145
146 pr_debug("sframe_type=%d nr=%d\n", sframe_type, nr);
147
148 skb = llc_shdlc_alloc_skb(shdlc, 0);
149 if (skb == NULL)
150 return -ENOMEM;
151
152 *(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_S | (sframe_type << 3) | nr;
153
154 r = shdlc->xmit_to_drv(shdlc->hdev, skb);
155
156 kfree_skb(skb);
157
158 return r;
159 }
160
161 /* immediately sends an U frame. skb may contain optional payload */
162 static int llc_shdlc_send_u_frame(const struct llc_shdlc *shdlc,
163 struct sk_buff *skb,
164 enum uframe_modifier uframe_modifier)
165 {
166 int r;
167
168 pr_debug("uframe_modifier=%d\n", uframe_modifier);
169
170 *(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_U | uframe_modifier;
171
172 r = shdlc->xmit_to_drv(shdlc->hdev, skb);
173
174 kfree_skb(skb);
175
176 return r;
177 }
178
179 /*
180 * Free ack_pending frames until y_nr - 1, and reset t2 according to
181 * the remaining oldest ack_pending frame sent time
182 */
183 static void llc_shdlc_reset_t2(struct llc_shdlc *shdlc, int y_nr)
184 {
185 struct sk_buff *skb;
186 int dnr = shdlc->dnr; /* MUST initially be < y_nr */
187
188 pr_debug("release ack pending up to frame %d excluded\n", y_nr);
189
190 while (dnr != y_nr) {
191 pr_debug("release ack pending frame %d\n", dnr);
192
193 skb = skb_dequeue(&shdlc->ack_pending_q);
194 kfree_skb(skb);
195
196 dnr = (dnr + 1) % 8;
197 }
198
199 if (skb_queue_empty(&shdlc->ack_pending_q)) {
200 if (shdlc->t2_active) {
201 del_timer_sync(&shdlc->t2_timer);
202 shdlc->t2_active = false;
203
204 pr_debug("All sent frames acked. Stopped T2(retransmit)\n");
205 }
206 } else {
207 skb = skb_peek(&shdlc->ack_pending_q);
208
209 mod_timer(&shdlc->t2_timer, *(unsigned long *)skb->cb +
210 msecs_to_jiffies(SHDLC_T2_VALUE_MS));
211 shdlc->t2_active = true;
212
213 pr_debug("Start T2(retransmit) for remaining unacked sent frames\n");
214 }
215 }
216
217 /*
218 * Receive validated frames from lower layer. skb contains HCI payload only.
219 * Handle according to algorithm at spec:10.8.2
220 */
221 static void llc_shdlc_rcv_i_frame(struct llc_shdlc *shdlc,
222 struct sk_buff *skb, int ns, int nr)
223 {
224 int x_ns = ns;
225 int y_nr = nr;
226
227 pr_debug("recvd I-frame %d, remote waiting frame %d\n", ns, nr);
228
229 if (shdlc->state != SHDLC_CONNECTED)
230 goto exit;
231
232 if (x_ns != shdlc->nr) {
233 llc_shdlc_send_s_frame(shdlc, S_FRAME_REJ, shdlc->nr);
234 goto exit;
235 }
236
237 if (!shdlc->t1_active) {
238 shdlc->t1_active = true;
239 mod_timer(&shdlc->t1_timer, jiffies +
240 msecs_to_jiffies(SHDLC_T1_VALUE_MS(shdlc->w)));
241 pr_debug("(re)Start T1(send ack)\n");
242 }
243
244 if (skb->len) {
245 shdlc->rcv_to_hci(shdlc->hdev, skb);
246 skb = NULL;
247 }
248
249 shdlc->nr = (shdlc->nr + 1) % 8;
250
251 if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) {
252 llc_shdlc_reset_t2(shdlc, y_nr);
253
254 shdlc->dnr = y_nr;
255 }
256
257 exit:
258 kfree_skb(skb);
259 }
260
261 static void llc_shdlc_rcv_ack(struct llc_shdlc *shdlc, int y_nr)
262 {
263 pr_debug("remote acked up to frame %d excluded\n", y_nr);
264
265 if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) {
266 llc_shdlc_reset_t2(shdlc, y_nr);
267 shdlc->dnr = y_nr;
268 }
269 }
270
271 static void llc_shdlc_requeue_ack_pending(struct llc_shdlc *shdlc)
272 {
273 struct sk_buff *skb;
274
275 pr_debug("ns reset to %d\n", shdlc->dnr);
276
277 while ((skb = skb_dequeue_tail(&shdlc->ack_pending_q))) {
278 skb_pull(skb, 1); /* remove control field */
279 skb_queue_head(&shdlc->send_q, skb);
280 }
281 shdlc->ns = shdlc->dnr;
282 }
283
284 static void llc_shdlc_rcv_rej(struct llc_shdlc *shdlc, int y_nr)
285 {
286 struct sk_buff *skb;
287
288 pr_debug("remote asks retransmission from frame %d\n", y_nr);
289
290 if (llc_shdlc_x_lteq_y_lt_z(shdlc->dnr, y_nr, shdlc->ns)) {
291 if (shdlc->t2_active) {
292 del_timer_sync(&shdlc->t2_timer);
293 shdlc->t2_active = false;
294 pr_debug("Stopped T2(retransmit)\n");
295 }
296
297 if (shdlc->dnr != y_nr) {
298 while ((shdlc->dnr = ((shdlc->dnr + 1) % 8)) != y_nr) {
299 skb = skb_dequeue(&shdlc->ack_pending_q);
300 kfree_skb(skb);
301 }
302 }
303
304 llc_shdlc_requeue_ack_pending(shdlc);
305 }
306 }
307
308 /* See spec RR:10.8.3 REJ:10.8.4 */
309 static void llc_shdlc_rcv_s_frame(struct llc_shdlc *shdlc,
310 enum sframe_type s_frame_type, int nr)
311 {
312 struct sk_buff *skb;
313
314 if (shdlc->state != SHDLC_CONNECTED)
315 return;
316
317 switch (s_frame_type) {
318 case S_FRAME_RR:
319 llc_shdlc_rcv_ack(shdlc, nr);
320 if (shdlc->rnr == true) { /* see SHDLC 10.7.7 */
321 shdlc->rnr = false;
322 if (shdlc->send_q.qlen == 0) {
323 skb = llc_shdlc_alloc_skb(shdlc, 0);
324 if (skb)
325 skb_queue_tail(&shdlc->send_q, skb);
326 }
327 }
328 break;
329 case S_FRAME_REJ:
330 llc_shdlc_rcv_rej(shdlc, nr);
331 break;
332 case S_FRAME_RNR:
333 llc_shdlc_rcv_ack(shdlc, nr);
334 shdlc->rnr = true;
335 break;
336 default:
337 break;
338 }
339 }
340
341 static void llc_shdlc_connect_complete(struct llc_shdlc *shdlc, int r)
342 {
343 pr_debug("result=%d\n", r);
344
345 del_timer_sync(&shdlc->connect_timer);
346
347 if (r == 0) {
348 shdlc->ns = 0;
349 shdlc->nr = 0;
350 shdlc->dnr = 0;
351
352 shdlc->state = SHDLC_HALF_CONNECTED;
353 } else {
354 shdlc->state = SHDLC_DISCONNECTED;
355 }
356
357 shdlc->connect_result = r;
358
359 wake_up(shdlc->connect_wq);
360 }
361
362 static int llc_shdlc_connect_initiate(const struct llc_shdlc *shdlc)
363 {
364 struct sk_buff *skb;
365
366 skb = llc_shdlc_alloc_skb(shdlc, 2);
367 if (skb == NULL)
368 return -ENOMEM;
369
370 skb_put_u8(skb, SHDLC_MAX_WINDOW);
371 skb_put_u8(skb, SHDLC_SREJ_SUPPORT ? 1 : 0);
372
373 return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_RSET);
374 }
375
376 static int llc_shdlc_connect_send_ua(const struct llc_shdlc *shdlc)
377 {
378 struct sk_buff *skb;
379
380 skb = llc_shdlc_alloc_skb(shdlc, 0);
381 if (skb == NULL)
382 return -ENOMEM;
383
384 return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_UA);
385 }
386
387 static void llc_shdlc_rcv_u_frame(struct llc_shdlc *shdlc,
388 struct sk_buff *skb,
389 enum uframe_modifier u_frame_modifier)
390 {
391 u8 w = SHDLC_MAX_WINDOW;
392 bool srej_support = SHDLC_SREJ_SUPPORT;
393 int r;
394
395 pr_debug("u_frame_modifier=%d\n", u_frame_modifier);
396
397 switch (u_frame_modifier) {
398 case U_FRAME_RSET:
399 switch (shdlc->state) {
400 case SHDLC_NEGOTIATING:
401 case SHDLC_CONNECTING:
402 /*
403 * We sent RSET, but chip wants to negotiate or we
404 * got RSET before we managed to send out our.
405 */
406 if (skb->len > 0)
407 w = skb->data[0];
408
409 if (skb->len > 1)
410 srej_support = skb->data[1] & 0x01 ? true :
411 false;
412
413 if ((w <= SHDLC_MAX_WINDOW) &&
414 (SHDLC_SREJ_SUPPORT || (srej_support == false))) {
415 shdlc->w = w;
416 shdlc->srej_support = srej_support;
417 r = llc_shdlc_connect_send_ua(shdlc);
418 llc_shdlc_connect_complete(shdlc, r);
419 }
420 break;
421 case SHDLC_HALF_CONNECTED:
422 /*
423 * Chip resent RSET due to its timeout - Ignote it
424 * as we already sent UA.
425 */
426 break;
427 case SHDLC_CONNECTED:
428 /*
429 * Chip wants to reset link. This is unexpected and
430 * unsupported.
431 */
432 shdlc->hard_fault = -ECONNRESET;
433 break;
434 default:
435 break;
436 }
437 break;
438 case U_FRAME_UA:
439 if ((shdlc->state == SHDLC_CONNECTING &&
440 shdlc->connect_tries > 0) ||
441 (shdlc->state == SHDLC_NEGOTIATING)) {
442 llc_shdlc_connect_complete(shdlc, 0);
443 shdlc->state = SHDLC_CONNECTED;
444 }
445 break;
446 default:
447 break;
448 }
449
450 kfree_skb(skb);
451 }
452
453 static void llc_shdlc_handle_rcv_queue(struct llc_shdlc *shdlc)
454 {
455 struct sk_buff *skb;
456 u8 control;
457 int nr;
458 int ns;
459 enum sframe_type s_frame_type;
460 enum uframe_modifier u_frame_modifier;
461
462 if (shdlc->rcv_q.qlen)
463 pr_debug("rcvQlen=%d\n", shdlc->rcv_q.qlen);
464
465 while ((skb = skb_dequeue(&shdlc->rcv_q)) != NULL) {
466 control = skb->data[0];
467 skb_pull(skb, 1);
468 switch (control & SHDLC_CONTROL_HEAD_MASK) {
469 case SHDLC_CONTROL_HEAD_I:
470 case SHDLC_CONTROL_HEAD_I2:
471 if (shdlc->state == SHDLC_HALF_CONNECTED)
472 shdlc->state = SHDLC_CONNECTED;
473
474 ns = (control & SHDLC_CONTROL_NS_MASK) >> 3;
475 nr = control & SHDLC_CONTROL_NR_MASK;
476 llc_shdlc_rcv_i_frame(shdlc, skb, ns, nr);
477 break;
478 case SHDLC_CONTROL_HEAD_S:
479 if (shdlc->state == SHDLC_HALF_CONNECTED)
480 shdlc->state = SHDLC_CONNECTED;
481
482 s_frame_type = (control & SHDLC_CONTROL_TYPE_MASK) >> 3;
483 nr = control & SHDLC_CONTROL_NR_MASK;
484 llc_shdlc_rcv_s_frame(shdlc, s_frame_type, nr);
485 kfree_skb(skb);
486 break;
487 case SHDLC_CONTROL_HEAD_U:
488 u_frame_modifier = control & SHDLC_CONTROL_M_MASK;
489 llc_shdlc_rcv_u_frame(shdlc, skb, u_frame_modifier);
490 break;
491 default:
492 pr_err("UNKNOWN Control=%d\n", control);
493 kfree_skb(skb);
494 break;
495 }
496 }
497 }
498
499 static int llc_shdlc_w_used(int ns, int dnr)
500 {
501 int unack_count;
502
503 if (dnr <= ns)
504 unack_count = ns - dnr;
505 else
506 unack_count = 8 - dnr + ns;
507
508 return unack_count;
509 }
510
511 /* Send frames according to algorithm at spec:10.8.1 */
512 static void llc_shdlc_handle_send_queue(struct llc_shdlc *shdlc)
513 {
514 struct sk_buff *skb;
515 int r;
516 unsigned long time_sent;
517
518 if (shdlc->send_q.qlen)
519 pr_debug("sendQlen=%d ns=%d dnr=%d rnr=%s w_room=%d unackQlen=%d\n",
520 shdlc->send_q.qlen, shdlc->ns, shdlc->dnr,
521 shdlc->rnr == false ? "false" : "true",
522 shdlc->w - llc_shdlc_w_used(shdlc->ns, shdlc->dnr),
523 shdlc->ack_pending_q.qlen);
524
525 while (shdlc->send_q.qlen && shdlc->ack_pending_q.qlen < shdlc->w &&
526 (shdlc->rnr == false)) {
527
528 if (shdlc->t1_active) {
529 del_timer_sync(&shdlc->t1_timer);
530 shdlc->t1_active = false;
531 pr_debug("Stopped T1(send ack)\n");
532 }
533
534 skb = skb_dequeue(&shdlc->send_q);
535
536 *(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_I | (shdlc->ns << 3) |
537 shdlc->nr;
538
539 pr_debug("Sending I-Frame %d, waiting to rcv %d\n", shdlc->ns,
540 shdlc->nr);
541 SHDLC_DUMP_SKB("shdlc frame written", skb);
542
543 r = shdlc->xmit_to_drv(shdlc->hdev, skb);
544 if (r < 0) {
545 shdlc->hard_fault = r;
546 break;
547 }
548
549 shdlc->ns = (shdlc->ns + 1) % 8;
550
551 time_sent = jiffies;
552 *(unsigned long *)skb->cb = time_sent;
553
554 skb_queue_tail(&shdlc->ack_pending_q, skb);
555
556 if (shdlc->t2_active == false) {
557 shdlc->t2_active = true;
558 mod_timer(&shdlc->t2_timer, time_sent +
559 msecs_to_jiffies(SHDLC_T2_VALUE_MS));
560 pr_debug("Started T2 (retransmit)\n");
561 }
562 }
563 }
564
565 static void llc_shdlc_connect_timeout(struct timer_list *t)
566 {
567 struct llc_shdlc *shdlc = from_timer(shdlc, t, connect_timer);
568
569 schedule_work(&shdlc->sm_work);
570 }
571
572 static void llc_shdlc_t1_timeout(struct timer_list *t)
573 {
574 struct llc_shdlc *shdlc = from_timer(shdlc, t, t1_timer);
575
576 pr_debug("SoftIRQ: need to send ack\n");
577
578 schedule_work(&shdlc->sm_work);
579 }
580
581 static void llc_shdlc_t2_timeout(struct timer_list *t)
582 {
583 struct llc_shdlc *shdlc = from_timer(shdlc, t, t2_timer);
584
585 pr_debug("SoftIRQ: need to retransmit\n");
586
587 schedule_work(&shdlc->sm_work);
588 }
589
590 static void llc_shdlc_sm_work(struct work_struct *work)
591 {
592 struct llc_shdlc *shdlc = container_of(work, struct llc_shdlc, sm_work);
593 int r;
594
595 mutex_lock(&shdlc->state_mutex);
596
597 switch (shdlc->state) {
598 case SHDLC_DISCONNECTED:
599 skb_queue_purge(&shdlc->rcv_q);
600 skb_queue_purge(&shdlc->send_q);
601 skb_queue_purge(&shdlc->ack_pending_q);
602 break;
603 case SHDLC_CONNECTING:
604 if (shdlc->hard_fault) {
605 llc_shdlc_connect_complete(shdlc, shdlc->hard_fault);
606 break;
607 }
608
609 if (shdlc->connect_tries++ < 5)
610 r = llc_shdlc_connect_initiate(shdlc);
611 else
612 r = -ETIME;
613 if (r < 0) {
614 llc_shdlc_connect_complete(shdlc, r);
615 } else {
616 mod_timer(&shdlc->connect_timer, jiffies +
617 msecs_to_jiffies(SHDLC_CONNECT_VALUE_MS));
618
619 shdlc->state = SHDLC_NEGOTIATING;
620 }
621 break;
622 case SHDLC_NEGOTIATING:
623 if (timer_pending(&shdlc->connect_timer) == 0) {
624 shdlc->state = SHDLC_CONNECTING;
625 schedule_work(&shdlc->sm_work);
626 }
627
628 llc_shdlc_handle_rcv_queue(shdlc);
629
630 if (shdlc->hard_fault) {
631 llc_shdlc_connect_complete(shdlc, shdlc->hard_fault);
632 break;
633 }
634 break;
635 case SHDLC_HALF_CONNECTED:
636 case SHDLC_CONNECTED:
637 llc_shdlc_handle_rcv_queue(shdlc);
638 llc_shdlc_handle_send_queue(shdlc);
639
640 if (shdlc->t1_active && timer_pending(&shdlc->t1_timer) == 0) {
641 pr_debug("Handle T1(send ack) elapsed (T1 now inactive)\n");
642
643 shdlc->t1_active = false;
644 r = llc_shdlc_send_s_frame(shdlc, S_FRAME_RR,
645 shdlc->nr);
646 if (r < 0)
647 shdlc->hard_fault = r;
648 }
649
650 if (shdlc->t2_active && timer_pending(&shdlc->t2_timer) == 0) {
651 pr_debug("Handle T2(retransmit) elapsed (T2 inactive)\n");
652
653 shdlc->t2_active = false;
654
655 llc_shdlc_requeue_ack_pending(shdlc);
656 llc_shdlc_handle_send_queue(shdlc);
657 }
658
659 if (shdlc->hard_fault)
660 shdlc->llc_failure(shdlc->hdev, shdlc->hard_fault);
661 break;
662 default:
663 break;
664 }
665 mutex_unlock(&shdlc->state_mutex);
666 }
667
668 /*
669 * Called from syscall context to establish shdlc link. Sleeps until
670 * link is ready or failure.
671 */
672 static int llc_shdlc_connect(struct llc_shdlc *shdlc)
673 {
674 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(connect_wq);
675
676 mutex_lock(&shdlc->state_mutex);
677
678 shdlc->state = SHDLC_CONNECTING;
679 shdlc->connect_wq = &connect_wq;
680 shdlc->connect_tries = 0;
681 shdlc->connect_result = 1;
682
683 mutex_unlock(&shdlc->state_mutex);
684
685 schedule_work(&shdlc->sm_work);
686
687 wait_event(connect_wq, shdlc->connect_result != 1);
688
689 return shdlc->connect_result;
690 }
691
692 static void llc_shdlc_disconnect(struct llc_shdlc *shdlc)
693 {
694 mutex_lock(&shdlc->state_mutex);
695
696 shdlc->state = SHDLC_DISCONNECTED;
697
698 mutex_unlock(&shdlc->state_mutex);
699
700 schedule_work(&shdlc->sm_work);
701 }
702
703 /*
704 * Receive an incoming shdlc frame. Frame has already been crc-validated.
705 * skb contains only LLC header and payload.
706 * If skb == NULL, it is a notification that the link below is dead.
707 */
708 static void llc_shdlc_recv_frame(struct llc_shdlc *shdlc, struct sk_buff *skb)
709 {
710 if (skb == NULL) {
711 pr_err("NULL Frame -> link is dead\n");
712 shdlc->hard_fault = -EREMOTEIO;
713 } else {
714 SHDLC_DUMP_SKB("incoming frame", skb);
715 skb_queue_tail(&shdlc->rcv_q, skb);
716 }
717
718 schedule_work(&shdlc->sm_work);
719 }
720
721 static void *llc_shdlc_init(struct nfc_hci_dev *hdev, xmit_to_drv_t xmit_to_drv,
722 rcv_to_hci_t rcv_to_hci, int tx_headroom,
723 int tx_tailroom, int *rx_headroom, int *rx_tailroom,
724 llc_failure_t llc_failure)
725 {
726 struct llc_shdlc *shdlc;
727
728 *rx_headroom = SHDLC_LLC_HEAD_ROOM;
729 *rx_tailroom = 0;
730
731 shdlc = kzalloc(sizeof(struct llc_shdlc), GFP_KERNEL);
732 if (shdlc == NULL)
733 return NULL;
734
735 mutex_init(&shdlc->state_mutex);
736 shdlc->state = SHDLC_DISCONNECTED;
737
738 timer_setup(&shdlc->connect_timer, llc_shdlc_connect_timeout, 0);
739 timer_setup(&shdlc->t1_timer, llc_shdlc_t1_timeout, 0);
740 timer_setup(&shdlc->t2_timer, llc_shdlc_t2_timeout, 0);
741
742 shdlc->w = SHDLC_MAX_WINDOW;
743 shdlc->srej_support = SHDLC_SREJ_SUPPORT;
744
745 skb_queue_head_init(&shdlc->rcv_q);
746 skb_queue_head_init(&shdlc->send_q);
747 skb_queue_head_init(&shdlc->ack_pending_q);
748
749 INIT_WORK(&shdlc->sm_work, llc_shdlc_sm_work);
750
751 shdlc->hdev = hdev;
752 shdlc->xmit_to_drv = xmit_to_drv;
753 shdlc->rcv_to_hci = rcv_to_hci;
754 shdlc->tx_headroom = tx_headroom;
755 shdlc->tx_tailroom = tx_tailroom;
756 shdlc->llc_failure = llc_failure;
757
758 return shdlc;
759 }
760
761 static void llc_shdlc_deinit(struct nfc_llc *llc)
762 {
763 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
764
765 skb_queue_purge(&shdlc->rcv_q);
766 skb_queue_purge(&shdlc->send_q);
767 skb_queue_purge(&shdlc->ack_pending_q);
768
769 kfree(shdlc);
770 }
771
772 static int llc_shdlc_start(struct nfc_llc *llc)
773 {
774 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
775
776 return llc_shdlc_connect(shdlc);
777 }
778
779 static int llc_shdlc_stop(struct nfc_llc *llc)
780 {
781 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
782
783 llc_shdlc_disconnect(shdlc);
784
785 return 0;
786 }
787
788 static void llc_shdlc_rcv_from_drv(struct nfc_llc *llc, struct sk_buff *skb)
789 {
790 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
791
792 llc_shdlc_recv_frame(shdlc, skb);
793 }
794
795 static int llc_shdlc_xmit_from_hci(struct nfc_llc *llc, struct sk_buff *skb)
796 {
797 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
798
799 skb_queue_tail(&shdlc->send_q, skb);
800
801 schedule_work(&shdlc->sm_work);
802
803 return 0;
804 }
805
806 static const struct nfc_llc_ops llc_shdlc_ops = {
807 .init = llc_shdlc_init,
808 .deinit = llc_shdlc_deinit,
809 .start = llc_shdlc_start,
810 .stop = llc_shdlc_stop,
811 .rcv_from_drv = llc_shdlc_rcv_from_drv,
812 .xmit_from_hci = llc_shdlc_xmit_from_hci,
813 };
814
815 int nfc_llc_shdlc_register(void)
816 {
817 return nfc_llc_register(LLC_SHDLC_NAME, &llc_shdlc_ops);
818 }
819
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.