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