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1/*
2 * shdlc Link Layer Control
3 *
4 * Copyright (C) 2012 Intel Corporation. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19#define pr_fmt(fmt) "shdlc: %s: " fmt, __func__
20
21#include <linux/types.h>
22#include <linux/sched.h>
23#include <linux/wait.h>
24#include <linux/slab.h>
25#include <linux/skbuff.h>
26
27#include "llc.h"
28
29enum shdlc_state {
30 SHDLC_DISCONNECTED = 0,
31 SHDLC_CONNECTING = 1,
32 SHDLC_NEGOTIATING = 2,
33 SHDLC_HALF_CONNECTED = 3,
34 SHDLC_CONNECTED = 4
35};
36
37struct llc_shdlc {
38 struct nfc_hci_dev *hdev;
39 xmit_to_drv_t xmit_to_drv;
40 rcv_to_hci_t rcv_to_hci;
41
42 struct mutex state_mutex;
43 enum shdlc_state state;
44 int hard_fault;
45
46 wait_queue_head_t *connect_wq;
47 int connect_tries;
48 int connect_result;
49 struct timer_list connect_timer;/* aka T3 in spec 10.6.1 */
50
51 u8 w; /* window size */
52 bool srej_support;
53
54 struct timer_list t1_timer; /* send ack timeout */
55 bool t1_active;
56
57 struct timer_list t2_timer; /* guard/retransmit timeout */
58 bool t2_active;
59
60 int ns; /* next seq num for send */
61 int nr; /* next expected seq num for receive */
62 int dnr; /* oldest sent unacked seq num */
63
64 struct sk_buff_head rcv_q;
65
66 struct sk_buff_head send_q;
67 bool rnr; /* other side is not ready to receive */
68
69 struct sk_buff_head ack_pending_q;
70
71 struct work_struct sm_work;
72
73 int tx_headroom;
74 int tx_tailroom;
75
76 llc_failure_t llc_failure;
77};
78
79#define SHDLC_LLC_HEAD_ROOM 2
80
81#define SHDLC_MAX_WINDOW 4
82#define SHDLC_SREJ_SUPPORT false
83
84#define SHDLC_CONTROL_HEAD_MASK 0xe0
85#define SHDLC_CONTROL_HEAD_I 0x80
86#define SHDLC_CONTROL_HEAD_I2 0xa0
87#define SHDLC_CONTROL_HEAD_S 0xc0
88#define SHDLC_CONTROL_HEAD_U 0xe0
89
90#define SHDLC_CONTROL_NS_MASK 0x38
91#define SHDLC_CONTROL_NR_MASK 0x07
92#define SHDLC_CONTROL_TYPE_MASK 0x18
93
94#define SHDLC_CONTROL_M_MASK 0x1f
95
96enum sframe_type {
97 S_FRAME_RR = 0x00,
98 S_FRAME_REJ = 0x01,
99 S_FRAME_RNR = 0x02,
100 S_FRAME_SREJ = 0x03
101};
102
103enum uframe_modifier {
104 U_FRAME_UA = 0x06,
105 U_FRAME_RSET = 0x19
106};
107
108#define SHDLC_CONNECT_VALUE_MS 5
109#define SHDLC_T1_VALUE_MS(w) ((5 * w) / 4)
110#define SHDLC_T2_VALUE_MS 300
111
112#define SHDLC_DUMP_SKB(info, skb) \
113do { \
114 pr_debug("%s:\n", info); \
115 print_hex_dump(KERN_DEBUG, "shdlc: ", DUMP_PREFIX_OFFSET, \
116 16, 1, skb->data, skb->len, 0); \
117} while (0)
118
119/* checks x < y <= z modulo 8 */
120static bool llc_shdlc_x_lt_y_lteq_z(int x, int y, int z)
121{
122 if (x < z)
123 return ((x < y) && (y <= z)) ? true : false;
124 else
125 return ((y > x) || (y <= z)) ? true : false;
126}
127
128/* checks x <= y < z modulo 8 */
129static bool llc_shdlc_x_lteq_y_lt_z(int x, int y, int z)
130{
131 if (x <= z)
132 return ((x <= y) && (y < z)) ? true : false;
133 else /* x > z -> z+8 > x */
134 return ((y >= x) || (y < z)) ? true : false;
135}
136
137static struct sk_buff *llc_shdlc_alloc_skb(struct llc_shdlc *shdlc,
138 int payload_len)
139{
140 struct sk_buff *skb;
141
142 skb = alloc_skb(shdlc->tx_headroom + SHDLC_LLC_HEAD_ROOM +
143 shdlc->tx_tailroom + payload_len, GFP_KERNEL);
144 if (skb)
145 skb_reserve(skb, shdlc->tx_headroom + SHDLC_LLC_HEAD_ROOM);
146
147 return skb;
148}
149
150/* immediately sends an S frame. */
151static int llc_shdlc_send_s_frame(struct llc_shdlc *shdlc,
152 enum sframe_type sframe_type, int nr)
153{
154 int r;
155 struct sk_buff *skb;
156
157 pr_debug("sframe_type=%d nr=%d\n", sframe_type, nr);
158
159 skb = llc_shdlc_alloc_skb(shdlc, 0);
160 if (skb == NULL)
161 return -ENOMEM;
162
163 *skb_push(skb, 1) = SHDLC_CONTROL_HEAD_S | (sframe_type << 3) | nr;
164
165 r = shdlc->xmit_to_drv(shdlc->hdev, skb);
166
167 kfree_skb(skb);
168
169 return r;
170}
171
172/* immediately sends an U frame. skb may contain optional payload */
173static int llc_shdlc_send_u_frame(struct llc_shdlc *shdlc,
174 struct sk_buff *skb,
175 enum uframe_modifier uframe_modifier)
176{
177 int r;
178
179 pr_debug("uframe_modifier=%d\n", uframe_modifier);
180
181 *skb_push(skb, 1) = SHDLC_CONTROL_HEAD_U | uframe_modifier;
182
183 r = shdlc->xmit_to_drv(shdlc->hdev, skb);
184
185 kfree_skb(skb);
186
187 return r;
188}
189
190/*
191 * Free ack_pending frames until y_nr - 1, and reset t2 according to
192 * the remaining oldest ack_pending frame sent time
193 */
194static void llc_shdlc_reset_t2(struct llc_shdlc *shdlc, int y_nr)
195{
196 struct sk_buff *skb;
197 int dnr = shdlc->dnr; /* MUST initially be < y_nr */
198
199 pr_debug("release ack pending up to frame %d excluded\n", y_nr);
200
201 while (dnr != y_nr) {
202 pr_debug("release ack pending frame %d\n", dnr);
203
204 skb = skb_dequeue(&shdlc->ack_pending_q);
205 kfree_skb(skb);
206
207 dnr = (dnr + 1) % 8;
208 }
209
210 if (skb_queue_empty(&shdlc->ack_pending_q)) {
211 if (shdlc->t2_active) {
212 del_timer_sync(&shdlc->t2_timer);
213 shdlc->t2_active = false;
214
215 pr_debug
216 ("All sent frames acked. Stopped T2(retransmit)\n");
217 }
218 } else {
219 skb = skb_peek(&shdlc->ack_pending_q);
220
221 mod_timer(&shdlc->t2_timer, *(unsigned long *)skb->cb +
222 msecs_to_jiffies(SHDLC_T2_VALUE_MS));
223 shdlc->t2_active = true;
224
225 pr_debug
226 ("Start T2(retransmit) for remaining unacked sent frames\n");
227 }
228}
229
230/*
231 * Receive validated frames from lower layer. skb contains HCI payload only.
232 * Handle according to algorithm at spec:10.8.2
233 */
234static void llc_shdlc_rcv_i_frame(struct llc_shdlc *shdlc,
235 struct sk_buff *skb, int ns, int nr)
236{
237 int x_ns = ns;
238 int y_nr = nr;
239
240 pr_debug("recvd I-frame %d, remote waiting frame %d\n", ns, nr);
241
242 if (shdlc->state != SHDLC_CONNECTED)
243 goto exit;
244
245 if (x_ns != shdlc->nr) {
246 llc_shdlc_send_s_frame(shdlc, S_FRAME_REJ, shdlc->nr);
247 goto exit;
248 }
249
250 if (shdlc->t1_active == false) {
251 shdlc->t1_active = true;
252 mod_timer(&shdlc->t1_timer, jiffies +
253 msecs_to_jiffies(SHDLC_T1_VALUE_MS(shdlc->w)));
254 pr_debug("(re)Start T1(send ack)\n");
255 }
256
257 if (skb->len) {
258 shdlc->rcv_to_hci(shdlc->hdev, skb);
259 skb = NULL;
260 }
261
262 shdlc->nr = (shdlc->nr + 1) % 8;
263
264 if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) {
265 llc_shdlc_reset_t2(shdlc, y_nr);
266
267 shdlc->dnr = y_nr;
268 }
269
270exit:
271 kfree_skb(skb);
272}
273
274static void llc_shdlc_rcv_ack(struct llc_shdlc *shdlc, int y_nr)
275{
276 pr_debug("remote acked up to frame %d excluded\n", y_nr);
277
278 if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) {
279 llc_shdlc_reset_t2(shdlc, y_nr);
280 shdlc->dnr = y_nr;
281 }
282}
283
284static void llc_shdlc_requeue_ack_pending(struct llc_shdlc *shdlc)
285{
286 struct sk_buff *skb;
287
288 pr_debug("ns reset to %d\n", shdlc->dnr);
289
290 while ((skb = skb_dequeue_tail(&shdlc->ack_pending_q))) {
291 skb_pull(skb, 1); /* remove control field */
292 skb_queue_head(&shdlc->send_q, skb);
293 }
294 shdlc->ns = shdlc->dnr;
295}
296
297static void llc_shdlc_rcv_rej(struct llc_shdlc *shdlc, int y_nr)
298{
299 struct sk_buff *skb;
300
301 pr_debug("remote asks retransmission from frame %d\n", y_nr);
302
303 if (llc_shdlc_x_lteq_y_lt_z(shdlc->dnr, y_nr, shdlc->ns)) {
304 if (shdlc->t2_active) {
305 del_timer_sync(&shdlc->t2_timer);
306 shdlc->t2_active = false;
307 pr_debug("Stopped T2(retransmit)\n");
308 }
309
310 if (shdlc->dnr != y_nr) {
311 while ((shdlc->dnr = ((shdlc->dnr + 1) % 8)) != y_nr) {
312 skb = skb_dequeue(&shdlc->ack_pending_q);
313 kfree_skb(skb);
314 }
315 }
316
317 llc_shdlc_requeue_ack_pending(shdlc);
318 }
319}
320
321/* See spec RR:10.8.3 REJ:10.8.4 */
322static void llc_shdlc_rcv_s_frame(struct llc_shdlc *shdlc,
323 enum sframe_type s_frame_type, int nr)
324{
325 struct sk_buff *skb;
326
327 if (shdlc->state != SHDLC_CONNECTED)
328 return;
329
330 switch (s_frame_type) {
331 case S_FRAME_RR:
332 llc_shdlc_rcv_ack(shdlc, nr);
333 if (shdlc->rnr == true) { /* see SHDLC 10.7.7 */
334 shdlc->rnr = false;
335 if (shdlc->send_q.qlen == 0) {
336 skb = llc_shdlc_alloc_skb(shdlc, 0);
337 if (skb)
338 skb_queue_tail(&shdlc->send_q, skb);
339 }
340 }
341 break;
342 case S_FRAME_REJ:
343 llc_shdlc_rcv_rej(shdlc, nr);
344 break;
345 case S_FRAME_RNR:
346 llc_shdlc_rcv_ack(shdlc, nr);
347 shdlc->rnr = true;
348 break;
349 default:
350 break;
351 }
352}
353
354static void llc_shdlc_connect_complete(struct llc_shdlc *shdlc, int r)
355{
356 pr_debug("result=%d\n", r);
357
358 del_timer_sync(&shdlc->connect_timer);
359
360 if (r == 0) {
361 shdlc->ns = 0;
362 shdlc->nr = 0;
363 shdlc->dnr = 0;
364
365 shdlc->state = SHDLC_HALF_CONNECTED;
366 } else {
367 shdlc->state = SHDLC_DISCONNECTED;
368 }
369
370 shdlc->connect_result = r;
371
372 wake_up(shdlc->connect_wq);
373}
374
375static int llc_shdlc_connect_initiate(struct llc_shdlc *shdlc)
376{
377 struct sk_buff *skb;
378
379 pr_debug("\n");
380
381 skb = llc_shdlc_alloc_skb(shdlc, 2);
382 if (skb == NULL)
383 return -ENOMEM;
384
385 *skb_put(skb, 1) = SHDLC_MAX_WINDOW;
386 *skb_put(skb, 1) = SHDLC_SREJ_SUPPORT ? 1 : 0;
387
388 return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_RSET);
389}
390
391static int llc_shdlc_connect_send_ua(struct llc_shdlc *shdlc)
392{
393 struct sk_buff *skb;
394
395 pr_debug("\n");
396
397 skb = llc_shdlc_alloc_skb(shdlc, 0);
398 if (skb == NULL)
399 return -ENOMEM;
400
401 return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_UA);
402}
403
404static void llc_shdlc_rcv_u_frame(struct llc_shdlc *shdlc,
405 struct sk_buff *skb,
406 enum uframe_modifier u_frame_modifier)
407{
408 u8 w = SHDLC_MAX_WINDOW;
409 bool srej_support = SHDLC_SREJ_SUPPORT;
410 int r;
411
412 pr_debug("u_frame_modifier=%d\n", u_frame_modifier);
413
414 switch (u_frame_modifier) {
415 case U_FRAME_RSET:
416 switch (shdlc->state) {
417 case SHDLC_NEGOTIATING:
418 case SHDLC_CONNECTING:
419 /*
420 * We sent RSET, but chip wants to negociate or we
421 * got RSET before we managed to send out our.
422 */
423 if (skb->len > 0)
424 w = skb->data[0];
425
426 if (skb->len > 1)
427 srej_support = skb->data[1] & 0x01 ? true :
428 false;
429
430 if ((w <= SHDLC_MAX_WINDOW) &&
431 (SHDLC_SREJ_SUPPORT || (srej_support == false))) {
432 shdlc->w = w;
433 shdlc->srej_support = srej_support;
434 r = llc_shdlc_connect_send_ua(shdlc);
435 llc_shdlc_connect_complete(shdlc, r);
436 }
437 break;
438 case SHDLC_HALF_CONNECTED:
439 /*
440 * Chip resent RSET due to its timeout - Ignote it
441 * as we already sent UA.
442 */
443 break;
444 case SHDLC_CONNECTED:
445 /*
446 * Chip wants to reset link. This is unexpected and
447 * unsupported.
448 */
449 shdlc->hard_fault = -ECONNRESET;
450 break;
451 default:
452 break;
453 }
454 break;
455 case U_FRAME_UA:
456 if ((shdlc->state == SHDLC_CONNECTING &&
457 shdlc->connect_tries > 0) ||
458 (shdlc->state == SHDLC_NEGOTIATING)) {
459 llc_shdlc_connect_complete(shdlc, 0);
460 shdlc->state = SHDLC_CONNECTED;
461 }
462 break;
463 default:
464 break;
465 }
466
467 kfree_skb(skb);
468}
469
470static void llc_shdlc_handle_rcv_queue(struct llc_shdlc *shdlc)
471{
472 struct sk_buff *skb;
473 u8 control;
474 int nr;
475 int ns;
476 enum sframe_type s_frame_type;
477 enum uframe_modifier u_frame_modifier;
478
479 if (shdlc->rcv_q.qlen)
480 pr_debug("rcvQlen=%d\n", shdlc->rcv_q.qlen);
481
482 while ((skb = skb_dequeue(&shdlc->rcv_q)) != NULL) {
483 control = skb->data[0];
484 skb_pull(skb, 1);
485 switch (control & SHDLC_CONTROL_HEAD_MASK) {
486 case SHDLC_CONTROL_HEAD_I:
487 case SHDLC_CONTROL_HEAD_I2:
488 if (shdlc->state == SHDLC_HALF_CONNECTED)
489 shdlc->state = SHDLC_CONNECTED;
490
491 ns = (control & SHDLC_CONTROL_NS_MASK) >> 3;
492 nr = control & SHDLC_CONTROL_NR_MASK;
493 llc_shdlc_rcv_i_frame(shdlc, skb, ns, nr);
494 break;
495 case SHDLC_CONTROL_HEAD_S:
496 if (shdlc->state == SHDLC_HALF_CONNECTED)
497 shdlc->state = SHDLC_CONNECTED;
498
499 s_frame_type = (control & SHDLC_CONTROL_TYPE_MASK) >> 3;
500 nr = control & SHDLC_CONTROL_NR_MASK;
501 llc_shdlc_rcv_s_frame(shdlc, s_frame_type, nr);
502 kfree_skb(skb);
503 break;
504 case SHDLC_CONTROL_HEAD_U:
505 u_frame_modifier = control & SHDLC_CONTROL_M_MASK;
506 llc_shdlc_rcv_u_frame(shdlc, skb, u_frame_modifier);
507 break;
508 default:
509 pr_err("UNKNOWN Control=%d\n", control);
510 kfree_skb(skb);
511 break;
512 }
513 }
514}
515
516static int llc_shdlc_w_used(int ns, int dnr)
517{
518 int unack_count;
519
520 if (dnr <= ns)
521 unack_count = ns - dnr;
522 else
523 unack_count = 8 - dnr + ns;
524
525 return unack_count;
526}
527
528/* Send frames according to algorithm at spec:10.8.1 */
529static void llc_shdlc_handle_send_queue(struct llc_shdlc *shdlc)
530{
531 struct sk_buff *skb;
532 int r;
533 unsigned long time_sent;
534
535 if (shdlc->send_q.qlen)
536 pr_debug
537 ("sendQlen=%d ns=%d dnr=%d rnr=%s w_room=%d unackQlen=%d\n",
538 shdlc->send_q.qlen, shdlc->ns, shdlc->dnr,
539 shdlc->rnr == false ? "false" : "true",
540 shdlc->w - llc_shdlc_w_used(shdlc->ns, shdlc->dnr),
541 shdlc->ack_pending_q.qlen);
542
543 while (shdlc->send_q.qlen && shdlc->ack_pending_q.qlen < shdlc->w &&
544 (shdlc->rnr == false)) {
545
546 if (shdlc->t1_active) {
547 del_timer_sync(&shdlc->t1_timer);
548 shdlc->t1_active = false;
549 pr_debug("Stopped T1(send ack)\n");
550 }
551
552 skb = skb_dequeue(&shdlc->send_q);
553
554 *skb_push(skb, 1) = SHDLC_CONTROL_HEAD_I | (shdlc->ns << 3) |
555 shdlc->nr;
556
557 pr_debug("Sending I-Frame %d, waiting to rcv %d\n", shdlc->ns,
558 shdlc->nr);
559 SHDLC_DUMP_SKB("shdlc frame written", skb);
560
561 r = shdlc->xmit_to_drv(shdlc->hdev, skb);
562 if (r < 0) {
563 shdlc->hard_fault = r;
564 break;
565 }
566
567 shdlc->ns = (shdlc->ns + 1) % 8;
568
569 time_sent = jiffies;
570 *(unsigned long *)skb->cb = time_sent;
571
572 skb_queue_tail(&shdlc->ack_pending_q, skb);
573
574 if (shdlc->t2_active == false) {
575 shdlc->t2_active = true;
576 mod_timer(&shdlc->t2_timer, time_sent +
577 msecs_to_jiffies(SHDLC_T2_VALUE_MS));
578 pr_debug("Started T2 (retransmit)\n");
579 }
580 }
581}
582
583static void llc_shdlc_connect_timeout(unsigned long data)
584{
585 struct llc_shdlc *shdlc = (struct llc_shdlc *)data;
586
587 pr_debug("\n");
588
589 schedule_work(&shdlc->sm_work);
590}
591
592static void llc_shdlc_t1_timeout(unsigned long data)
593{
594 struct llc_shdlc *shdlc = (struct llc_shdlc *)data;
595
596 pr_debug("SoftIRQ: need to send ack\n");
597
598 schedule_work(&shdlc->sm_work);
599}
600
601static void llc_shdlc_t2_timeout(unsigned long data)
602{
603 struct llc_shdlc *shdlc = (struct llc_shdlc *)data;
604
605 pr_debug("SoftIRQ: need to retransmit\n");
606
607 schedule_work(&shdlc->sm_work);
608}
609
610static void llc_shdlc_sm_work(struct work_struct *work)
611{
612 struct llc_shdlc *shdlc = container_of(work, struct llc_shdlc, sm_work);
613 int r;
614
615 pr_debug("\n");
616
617 mutex_lock(&shdlc->state_mutex);
618
619 switch (shdlc->state) {
620 case SHDLC_DISCONNECTED:
621 skb_queue_purge(&shdlc->rcv_q);
622 skb_queue_purge(&shdlc->send_q);
623 skb_queue_purge(&shdlc->ack_pending_q);
624 break;
625 case SHDLC_CONNECTING:
626 if (shdlc->hard_fault) {
627 llc_shdlc_connect_complete(shdlc, shdlc->hard_fault);
628 break;
629 }
630
631 if (shdlc->connect_tries++ < 5)
632 r = llc_shdlc_connect_initiate(shdlc);
633 else
634 r = -ETIME;
635 if (r < 0) {
636 llc_shdlc_connect_complete(shdlc, r);
637 } else {
638 mod_timer(&shdlc->connect_timer, jiffies +
639 msecs_to_jiffies(SHDLC_CONNECT_VALUE_MS));
640
641 shdlc->state = SHDLC_NEGOTIATING;
642 }
643 break;
644 case SHDLC_NEGOTIATING:
645 if (timer_pending(&shdlc->connect_timer) == 0) {
646 shdlc->state = SHDLC_CONNECTING;
647 schedule_work(&shdlc->sm_work);
648 }
649
650 llc_shdlc_handle_rcv_queue(shdlc);
651
652 if (shdlc->hard_fault) {
653 llc_shdlc_connect_complete(shdlc, shdlc->hard_fault);
654 break;
655 }
656 break;
657 case SHDLC_HALF_CONNECTED:
658 case SHDLC_CONNECTED:
659 llc_shdlc_handle_rcv_queue(shdlc);
660 llc_shdlc_handle_send_queue(shdlc);
661
662 if (shdlc->t1_active && timer_pending(&shdlc->t1_timer) == 0) {
663 pr_debug
664 ("Handle T1(send ack) elapsed (T1 now inactive)\n");
665
666 shdlc->t1_active = false;
667 r = llc_shdlc_send_s_frame(shdlc, S_FRAME_RR,
668 shdlc->nr);
669 if (r < 0)
670 shdlc->hard_fault = r;
671 }
672
673 if (shdlc->t2_active && timer_pending(&shdlc->t2_timer) == 0) {
674 pr_debug
675 ("Handle T2(retransmit) elapsed (T2 inactive)\n");
676
677 shdlc->t2_active = false;
678
679 llc_shdlc_requeue_ack_pending(shdlc);
680 llc_shdlc_handle_send_queue(shdlc);
681 }
682
683 if (shdlc->hard_fault)
684 shdlc->llc_failure(shdlc->hdev, shdlc->hard_fault);
685 break;
686 default:
687 break;
688 }
689 mutex_unlock(&shdlc->state_mutex);
690}
691
692/*
693 * Called from syscall context to establish shdlc link. Sleeps until
694 * link is ready or failure.
695 */
696static int llc_shdlc_connect(struct llc_shdlc *shdlc)
697{
698 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(connect_wq);
699
700 pr_debug("\n");
701
702 mutex_lock(&shdlc->state_mutex);
703
704 shdlc->state = SHDLC_CONNECTING;
705 shdlc->connect_wq = &connect_wq;
706 shdlc->connect_tries = 0;
707 shdlc->connect_result = 1;
708
709 mutex_unlock(&shdlc->state_mutex);
710
711 schedule_work(&shdlc->sm_work);
712
713 wait_event(connect_wq, shdlc->connect_result != 1);
714
715 return shdlc->connect_result;
716}
717
718static void llc_shdlc_disconnect(struct llc_shdlc *shdlc)
719{
720 pr_debug("\n");
721
722 mutex_lock(&shdlc->state_mutex);
723
724 shdlc->state = SHDLC_DISCONNECTED;
725
726 mutex_unlock(&shdlc->state_mutex);
727
728 schedule_work(&shdlc->sm_work);
729}
730
731/*
732 * Receive an incoming shdlc frame. Frame has already been crc-validated.
733 * skb contains only LLC header and payload.
734 * If skb == NULL, it is a notification that the link below is dead.
735 */
736static void llc_shdlc_recv_frame(struct llc_shdlc *shdlc, struct sk_buff *skb)
737{
738 if (skb == NULL) {
739 pr_err("NULL Frame -> link is dead\n");
740 shdlc->hard_fault = -EREMOTEIO;
741 } else {
742 SHDLC_DUMP_SKB("incoming frame", skb);
743 skb_queue_tail(&shdlc->rcv_q, skb);
744 }
745
746 schedule_work(&shdlc->sm_work);
747}
748
749static void *llc_shdlc_init(struct nfc_hci_dev *hdev, xmit_to_drv_t xmit_to_drv,
750 rcv_to_hci_t rcv_to_hci, int tx_headroom,
751 int tx_tailroom, int *rx_headroom, int *rx_tailroom,
752 llc_failure_t llc_failure)
753{
754 struct llc_shdlc *shdlc;
755
756 *rx_headroom = SHDLC_LLC_HEAD_ROOM;
757 *rx_tailroom = 0;
758
759 shdlc = kzalloc(sizeof(struct llc_shdlc), GFP_KERNEL);
760 if (shdlc == NULL)
761 return NULL;
762
763 mutex_init(&shdlc->state_mutex);
764 shdlc->state = SHDLC_DISCONNECTED;
765
766 init_timer(&shdlc->connect_timer);
767 shdlc->connect_timer.data = (unsigned long)shdlc;
768 shdlc->connect_timer.function = llc_shdlc_connect_timeout;
769
770 init_timer(&shdlc->t1_timer);
771 shdlc->t1_timer.data = (unsigned long)shdlc;
772 shdlc->t1_timer.function = llc_shdlc_t1_timeout;
773
774 init_timer(&shdlc->t2_timer);
775 shdlc->t2_timer.data = (unsigned long)shdlc;
776 shdlc->t2_timer.function = llc_shdlc_t2_timeout;
777
778 shdlc->w = SHDLC_MAX_WINDOW;
779 shdlc->srej_support = SHDLC_SREJ_SUPPORT;
780
781 skb_queue_head_init(&shdlc->rcv_q);
782 skb_queue_head_init(&shdlc->send_q);
783 skb_queue_head_init(&shdlc->ack_pending_q);
784
785 INIT_WORK(&shdlc->sm_work, llc_shdlc_sm_work);
786
787 shdlc->hdev = hdev;
788 shdlc->xmit_to_drv = xmit_to_drv;
789 shdlc->rcv_to_hci = rcv_to_hci;
790 shdlc->tx_headroom = tx_headroom;
791 shdlc->tx_tailroom = tx_tailroom;
792 shdlc->llc_failure = llc_failure;
793
794 return shdlc;
795}
796
797static void llc_shdlc_deinit(struct nfc_llc *llc)
798{
799 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
800
801 skb_queue_purge(&shdlc->rcv_q);
802 skb_queue_purge(&shdlc->send_q);
803 skb_queue_purge(&shdlc->ack_pending_q);
804
805 kfree(shdlc);
806}
807
808static int llc_shdlc_start(struct nfc_llc *llc)
809{
810 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
811
812 return llc_shdlc_connect(shdlc);
813}
814
815static int llc_shdlc_stop(struct nfc_llc *llc)
816{
817 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
818
819 llc_shdlc_disconnect(shdlc);
820
821 return 0;
822}
823
824static void llc_shdlc_rcv_from_drv(struct nfc_llc *llc, struct sk_buff *skb)
825{
826 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
827
828 llc_shdlc_recv_frame(shdlc, skb);
829}
830
831static int llc_shdlc_xmit_from_hci(struct nfc_llc *llc, struct sk_buff *skb)
832{
833 struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
834
835 skb_queue_tail(&shdlc->send_q, skb);
836
837 schedule_work(&shdlc->sm_work);
838
839 return 0;
840}
841
842static struct nfc_llc_ops llc_shdlc_ops = {
843 .init = llc_shdlc_init,
844 .deinit = llc_shdlc_deinit,
845 .start = llc_shdlc_start,
846 .stop = llc_shdlc_stop,
847 .rcv_from_drv = llc_shdlc_rcv_from_drv,
848 .xmit_from_hci = llc_shdlc_xmit_from_hci,
849};
850
851int nfc_llc_shdlc_register(void)
852{
853 return nfc_llc_register(LLC_SHDLC_NAME, &llc_shdlc_ops);
854}