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 205 ("All sent frames acked. Stopped T2(retransmit)\n"); 206 } 207 } else { 208 skb = skb_peek(&shdlc->ack_pending_q); 209 210 mod_timer(&shdlc->t2_timer, *(unsigned long *)skb->cb + 211 msecs_to_jiffies(SHDLC_T2_VALUE_MS)); 212 shdlc->t2_active = true; 213 214 pr_debug 215 ("Start T2(retransmit) for remaining unacked sent frames\n"); 216 } 217 } 218 219 /* 220 * Receive validated frames from lower layer. skb contains HCI payload only. 221 * Handle according to algorithm at spec:10.8.2 222 */ 223 static void llc_shdlc_rcv_i_frame(struct llc_shdlc *shdlc, 224 struct sk_buff *skb, int ns, int nr) 225 { 226 int x_ns = ns; 227 int y_nr = nr; 228 229 pr_debug("recvd I-frame %d, remote waiting frame %d\n", ns, nr); 230 231 if (shdlc->state != SHDLC_CONNECTED) 232 goto exit; 233 234 if (x_ns != shdlc->nr) { 235 llc_shdlc_send_s_frame(shdlc, S_FRAME_REJ, shdlc->nr); 236 goto exit; 237 } 238 239 if (!shdlc->t1_active) { 240 shdlc->t1_active = true; 241 mod_timer(&shdlc->t1_timer, jiffies + 242 msecs_to_jiffies(SHDLC_T1_VALUE_MS(shdlc->w))); 243 pr_debug("(re)Start T1(send ack)\n"); 244 } 245 246 if (skb->len) { 247 shdlc->rcv_to_hci(shdlc->hdev, skb); 248 skb = NULL; 249 } 250 251 shdlc->nr = (shdlc->nr + 1) % 8; 252 253 if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) { 254 llc_shdlc_reset_t2(shdlc, y_nr); 255 256 shdlc->dnr = y_nr; 257 } 258 259 exit: 260 kfree_skb(skb); 261 } 262 263 static void llc_shdlc_rcv_ack(struct llc_shdlc *shdlc, int y_nr) 264 { 265 pr_debug("remote acked up to frame %d excluded\n", y_nr); 266 267 if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) { 268 llc_shdlc_reset_t2(shdlc, y_nr); 269 shdlc->dnr = y_nr; 270 } 271 } 272 273 static void llc_shdlc_requeue_ack_pending(struct llc_shdlc *shdlc) 274 { 275 struct sk_buff *skb; 276 277 pr_debug("ns reset to %d\n", shdlc->dnr); 278 279 while ((skb = skb_dequeue_tail(&shdlc->ack_pending_q))) { 280 skb_pull(skb, 1); /* remove control field */ 281 skb_queue_head(&shdlc->send_q, skb); 282 } 283 shdlc->ns = shdlc->dnr; 284 } 285 286 static void llc_shdlc_rcv_rej(struct llc_shdlc *shdlc, int y_nr) 287 { 288 struct sk_buff *skb; 289 290 pr_debug("remote asks retransmission from frame %d\n", y_nr); 291 292 if (llc_shdlc_x_lteq_y_lt_z(shdlc->dnr, y_nr, shdlc->ns)) { 293 if (shdlc->t2_active) { 294 del_timer_sync(&shdlc->t2_timer); 295 shdlc->t2_active = false; 296 pr_debug("Stopped T2(retransmit)\n"); 297 } 298 299 if (shdlc->dnr != y_nr) { 300 while ((shdlc->dnr = ((shdlc->dnr + 1) % 8)) != y_nr) { 301 skb = skb_dequeue(&shdlc->ack_pending_q); 302 kfree_skb(skb); 303 } 304 } 305 306 llc_shdlc_requeue_ack_pending(shdlc); 307 } 308 } 309 310 /* See spec RR:10.8.3 REJ:10.8.4 */ 311 static void llc_shdlc_rcv_s_frame(struct llc_shdlc *shdlc, 312 enum sframe_type s_frame_type, int nr) 313 { 314 struct sk_buff *skb; 315 316 if (shdlc->state != SHDLC_CONNECTED) 317 return; 318 319 switch (s_frame_type) { 320 case S_FRAME_RR: 321 llc_shdlc_rcv_ack(shdlc, nr); 322 if (shdlc->rnr == true) { /* see SHDLC 10.7.7 */ 323 shdlc->rnr = false; 324 if (shdlc->send_q.qlen == 0) { 325 skb = llc_shdlc_alloc_skb(shdlc, 0); 326 if (skb) 327 skb_queue_tail(&shdlc->send_q, skb); 328 } 329 } 330 break; 331 case S_FRAME_REJ: 332 llc_shdlc_rcv_rej(shdlc, nr); 333 break; 334 case S_FRAME_RNR: 335 llc_shdlc_rcv_ack(shdlc, nr); 336 shdlc->rnr = true; 337 break; 338 default: 339 break; 340 } 341 } 342 343 static void llc_shdlc_connect_complete(struct llc_shdlc *shdlc, int r) 344 { 345 pr_debug("result=%d\n", r); 346 347 del_timer_sync(&shdlc->connect_timer); 348 349 if (r == 0) { 350 shdlc->ns = 0; 351 shdlc->nr = 0; 352 shdlc->dnr = 0; 353 354 shdlc->state = SHDLC_HALF_CONNECTED; 355 } else { 356 shdlc->state = SHDLC_DISCONNECTED; 357 } 358 359 shdlc->connect_result = r; 360 361 wake_up(shdlc->connect_wq); 362 } 363 364 static int llc_shdlc_connect_initiate(const struct llc_shdlc *shdlc) 365 { 366 struct sk_buff *skb; 367 368 pr_debug("\n"); 369 370 skb = llc_shdlc_alloc_skb(shdlc, 2); 371 if (skb == NULL) 372 return -ENOMEM; 373 374 skb_put_u8(skb, SHDLC_MAX_WINDOW); 375 skb_put_u8(skb, SHDLC_SREJ_SUPPORT ? 1 : 0); 376 377 return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_RSET); 378 } 379 380 static int llc_shdlc_connect_send_ua(const struct llc_shdlc *shdlc) 381 { 382 struct sk_buff *skb; 383 384 pr_debug("\n"); 385 386 skb = llc_shdlc_alloc_skb(shdlc, 0); 387 if (skb == NULL) 388 return -ENOMEM; 389 390 return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_UA); 391 } 392 393 static void llc_shdlc_rcv_u_frame(struct llc_shdlc *shdlc, 394 struct sk_buff *skb, 395 enum uframe_modifier u_frame_modifier) 396 { 397 u8 w = SHDLC_MAX_WINDOW; 398 bool srej_support = SHDLC_SREJ_SUPPORT; 399 int r; 400 401 pr_debug("u_frame_modifier=%d\n", u_frame_modifier); 402 403 switch (u_frame_modifier) { 404 case U_FRAME_RSET: 405 switch (shdlc->state) { 406 case SHDLC_NEGOTIATING: 407 case SHDLC_CONNECTING: 408 /* 409 * We sent RSET, but chip wants to negotiate or we 410 * got RSET before we managed to send out our. 411 */ 412 if (skb->len > 0) 413 w = skb->data[0]; 414 415 if (skb->len > 1) 416 srej_support = skb->data[1] & 0x01 ? true : 417 false; 418 419 if ((w <= SHDLC_MAX_WINDOW) && 420 (SHDLC_SREJ_SUPPORT || (srej_support == false))) { 421 shdlc->w = w; 422 shdlc->srej_support = srej_support; 423 r = llc_shdlc_connect_send_ua(shdlc); 424 llc_shdlc_connect_complete(shdlc, r); 425 } 426 break; 427 case SHDLC_HALF_CONNECTED: 428 /* 429 * Chip resent RSET due to its timeout - Ignote it 430 * as we already sent UA. 431 */ 432 break; 433 case SHDLC_CONNECTED: 434 /* 435 * Chip wants to reset link. This is unexpected and 436 * unsupported. 437 */ 438 shdlc->hard_fault = -ECONNRESET; 439 break; 440 default: 441 break; 442 } 443 break; 444 case U_FRAME_UA: 445 if ((shdlc->state == SHDLC_CONNECTING && 446 shdlc->connect_tries > 0) || 447 (shdlc->state == SHDLC_NEGOTIATING)) { 448 llc_shdlc_connect_complete(shdlc, 0); 449 shdlc->state = SHDLC_CONNECTED; 450 } 451 break; 452 default: 453 break; 454 } 455 456 kfree_skb(skb); 457 } 458 459 static void llc_shdlc_handle_rcv_queue(struct llc_shdlc *shdlc) 460 { 461 struct sk_buff *skb; 462 u8 control; 463 int nr; 464 int ns; 465 enum sframe_type s_frame_type; 466 enum uframe_modifier u_frame_modifier; 467 468 if (shdlc->rcv_q.qlen) 469 pr_debug("rcvQlen=%d\n", shdlc->rcv_q.qlen); 470 471 while ((skb = skb_dequeue(&shdlc->rcv_q)) != NULL) { 472 control = skb->data[0]; 473 skb_pull(skb, 1); 474 switch (control & SHDLC_CONTROL_HEAD_MASK) { 475 case SHDLC_CONTROL_HEAD_I: 476 case SHDLC_CONTROL_HEAD_I2: 477 if (shdlc->state == SHDLC_HALF_CONNECTED) 478 shdlc->state = SHDLC_CONNECTED; 479 480 ns = (control & SHDLC_CONTROL_NS_MASK) >> 3; 481 nr = control & SHDLC_CONTROL_NR_MASK; 482 llc_shdlc_rcv_i_frame(shdlc, skb, ns, nr); 483 break; 484 case SHDLC_CONTROL_HEAD_S: 485 if (shdlc->state == SHDLC_HALF_CONNECTED) 486 shdlc->state = SHDLC_CONNECTED; 487 488 s_frame_type = (control & SHDLC_CONTROL_TYPE_MASK) >> 3; 489 nr = control & SHDLC_CONTROL_NR_MASK; 490 llc_shdlc_rcv_s_frame(shdlc, s_frame_type, nr); 491 kfree_skb(skb); 492 break; 493 case SHDLC_CONTROL_HEAD_U: 494 u_frame_modifier = control & SHDLC_CONTROL_M_MASK; 495 llc_shdlc_rcv_u_frame(shdlc, skb, u_frame_modifier); 496 break; 497 default: 498 pr_err("UNKNOWN Control=%d\n", control); 499 kfree_skb(skb); 500 break; 501 } 502 } 503 } 504 505 static int llc_shdlc_w_used(int ns, int dnr) 506 { 507 int unack_count; 508 509 if (dnr <= ns) 510 unack_count = ns - dnr; 511 else 512 unack_count = 8 - dnr + ns; 513 514 return unack_count; 515 } 516 517 /* Send frames according to algorithm at spec:10.8.1 */ 518 static void llc_shdlc_handle_send_queue(struct llc_shdlc *shdlc) 519 { 520 struct sk_buff *skb; 521 int r; 522 unsigned long time_sent; 523 524 if (shdlc->send_q.qlen) 525 pr_debug 526 ("sendQlen=%d ns=%d dnr=%d rnr=%s w_room=%d unackQlen=%d\n", 527 shdlc->send_q.qlen, shdlc->ns, shdlc->dnr, 528 shdlc->rnr == false ? "false" : "true", 529 shdlc->w - llc_shdlc_w_used(shdlc->ns, shdlc->dnr), 530 shdlc->ack_pending_q.qlen); 531 532 while (shdlc->send_q.qlen && shdlc->ack_pending_q.qlen < shdlc->w && 533 (shdlc->rnr == false)) { 534 535 if (shdlc->t1_active) { 536 del_timer_sync(&shdlc->t1_timer); 537 shdlc->t1_active = false; 538 pr_debug("Stopped T1(send ack)\n"); 539 } 540 541 skb = skb_dequeue(&shdlc->send_q); 542 543 *(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_I | (shdlc->ns << 3) | 544 shdlc->nr; 545 546 pr_debug("Sending I-Frame %d, waiting to rcv %d\n", shdlc->ns, 547 shdlc->nr); 548 SHDLC_DUMP_SKB("shdlc frame written", skb); 549 550 r = shdlc->xmit_to_drv(shdlc->hdev, skb); 551 if (r < 0) { 552 shdlc->hard_fault = r; 553 break; 554 } 555 556 shdlc->ns = (shdlc->ns + 1) % 8; 557 558 time_sent = jiffies; 559 *(unsigned long *)skb->cb = time_sent; 560 561 skb_queue_tail(&shdlc->ack_pending_q, skb); 562 563 if (shdlc->t2_active == false) { 564 shdlc->t2_active = true; 565 mod_timer(&shdlc->t2_timer, time_sent + 566 msecs_to_jiffies(SHDLC_T2_VALUE_MS)); 567 pr_debug("Started T2 (retransmit)\n"); 568 } 569 } 570 } 571 572 static void llc_shdlc_connect_timeout(struct timer_list *t) 573 { 574 struct llc_shdlc *shdlc = from_timer(shdlc, t, connect_timer); 575 576 pr_debug("\n"); 577 578 schedule_work(&shdlc->sm_work); 579 } 580 581 static void llc_shdlc_t1_timeout(struct timer_list *t) 582 { 583 struct llc_shdlc *shdlc = from_timer(shdlc, t, t1_timer); 584 585 pr_debug("SoftIRQ: need to send ack\n"); 586 587 schedule_work(&shdlc->sm_work); 588 } 589 590 static void llc_shdlc_t2_timeout(struct timer_list *t) 591 { 592 struct llc_shdlc *shdlc = from_timer(shdlc, t, t2_timer); 593 594 pr_debug("SoftIRQ: need to retransmit\n"); 595 596 schedule_work(&shdlc->sm_work); 597 } 598 599 static void llc_shdlc_sm_work(struct work_struct *work) 600 { 601 struct llc_shdlc *shdlc = container_of(work, struct llc_shdlc, sm_work); 602 int r; 603 604 pr_debug("\n"); 605 606 mutex_lock(&shdlc->state_mutex); 607 608 switch (shdlc->state) { 609 case SHDLC_DISCONNECTED: 610 skb_queue_purge(&shdlc->rcv_q); 611 skb_queue_purge(&shdlc->send_q); 612 skb_queue_purge(&shdlc->ack_pending_q); 613 break; 614 case SHDLC_CONNECTING: 615 if (shdlc->hard_fault) { 616 llc_shdlc_connect_complete(shdlc, shdlc->hard_fault); 617 break; 618 } 619 620 if (shdlc->connect_tries++ < 5) 621 r = llc_shdlc_connect_initiate(shdlc); 622 else 623 r = -ETIME; 624 if (r < 0) { 625 llc_shdlc_connect_complete(shdlc, r); 626 } else { 627 mod_timer(&shdlc->connect_timer, jiffies + 628 msecs_to_jiffies(SHDLC_CONNECT_VALUE_MS)); 629 630 shdlc->state = SHDLC_NEGOTIATING; 631 } 632 break; 633 case SHDLC_NEGOTIATING: 634 if (timer_pending(&shdlc->connect_timer) == 0) { 635 shdlc->state = SHDLC_CONNECTING; 636 schedule_work(&shdlc->sm_work); 637 } 638 639 llc_shdlc_handle_rcv_queue(shdlc); 640 641 if (shdlc->hard_fault) { 642 llc_shdlc_connect_complete(shdlc, shdlc->hard_fault); 643 break; 644 } 645 break; 646 case SHDLC_HALF_CONNECTED: 647 case SHDLC_CONNECTED: 648 llc_shdlc_handle_rcv_queue(shdlc); 649 llc_shdlc_handle_send_queue(shdlc); 650 651 if (shdlc->t1_active && timer_pending(&shdlc->t1_timer) == 0) { 652 pr_debug 653 ("Handle T1(send ack) elapsed (T1 now inactive)\n"); 654 655 shdlc->t1_active = false; 656 r = llc_shdlc_send_s_frame(shdlc, S_FRAME_RR, 657 shdlc->nr); 658 if (r < 0) 659 shdlc->hard_fault = r; 660 } 661 662 if (shdlc->t2_active && timer_pending(&shdlc->t2_timer) == 0) { 663 pr_debug 664 ("Handle T2(retransmit) elapsed (T2 inactive)\n"); 665 666 shdlc->t2_active = false; 667 668 llc_shdlc_requeue_ack_pending(shdlc); 669 llc_shdlc_handle_send_queue(shdlc); 670 } 671 672 if (shdlc->hard_fault) 673 shdlc->llc_failure(shdlc->hdev, shdlc->hard_fault); 674 break; 675 default: 676 break; 677 } 678 mutex_unlock(&shdlc->state_mutex); 679 } 680 681 /* 682 * Called from syscall context to establish shdlc link. Sleeps until 683 * link is ready or failure. 684 */ 685 static int llc_shdlc_connect(struct llc_shdlc *shdlc) 686 { 687 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(connect_wq); 688 689 pr_debug("\n"); 690 691 mutex_lock(&shdlc->state_mutex); 692 693 shdlc->state = SHDLC_CONNECTING; 694 shdlc->connect_wq = &connect_wq; 695 shdlc->connect_tries = 0; 696 shdlc->connect_result = 1; 697 698 mutex_unlock(&shdlc->state_mutex); 699 700 schedule_work(&shdlc->sm_work); 701 702 wait_event(connect_wq, shdlc->connect_result != 1); 703 704 return shdlc->connect_result; 705 } 706 707 static void llc_shdlc_disconnect(struct llc_shdlc *shdlc) 708 { 709 pr_debug("\n"); 710 711 mutex_lock(&shdlc->state_mutex); 712 713 shdlc->state = SHDLC_DISCONNECTED; 714 715 mutex_unlock(&shdlc->state_mutex); 716 717 schedule_work(&shdlc->sm_work); 718 } 719 720 /* 721 * Receive an incoming shdlc frame. Frame has already been crc-validated. 722 * skb contains only LLC header and payload. 723 * If skb == NULL, it is a notification that the link below is dead. 724 */ 725 static void llc_shdlc_recv_frame(struct llc_shdlc *shdlc, struct sk_buff *skb) 726 { 727 if (skb == NULL) { 728 pr_err("NULL Frame -> link is dead\n"); 729 shdlc->hard_fault = -EREMOTEIO; 730 } else { 731 SHDLC_DUMP_SKB("incoming frame", skb); 732 skb_queue_tail(&shdlc->rcv_q, skb); 733 } 734 735 schedule_work(&shdlc->sm_work); 736 } 737 738 static void *llc_shdlc_init(struct nfc_hci_dev *hdev, xmit_to_drv_t xmit_to_drv, 739 rcv_to_hci_t rcv_to_hci, int tx_headroom, 740 int tx_tailroom, int *rx_headroom, int *rx_tailroom, 741 llc_failure_t llc_failure) 742 { 743 struct llc_shdlc *shdlc; 744 745 *rx_headroom = SHDLC_LLC_HEAD_ROOM; 746 *rx_tailroom = 0; 747 748 shdlc = kzalloc(sizeof(struct llc_shdlc), GFP_KERNEL); 749 if (shdlc == NULL) 750 return NULL; 751 752 mutex_init(&shdlc->state_mutex); 753 shdlc->state = SHDLC_DISCONNECTED; 754 755 timer_setup(&shdlc->connect_timer, llc_shdlc_connect_timeout, 0); 756 timer_setup(&shdlc->t1_timer, llc_shdlc_t1_timeout, 0); 757 timer_setup(&shdlc->t2_timer, llc_shdlc_t2_timeout, 0); 758 759 shdlc->w = SHDLC_MAX_WINDOW; 760 shdlc->srej_support = SHDLC_SREJ_SUPPORT; 761 762 skb_queue_head_init(&shdlc->rcv_q); 763 skb_queue_head_init(&shdlc->send_q); 764 skb_queue_head_init(&shdlc->ack_pending_q); 765 766 INIT_WORK(&shdlc->sm_work, llc_shdlc_sm_work); 767 768 shdlc->hdev = hdev; 769 shdlc->xmit_to_drv = xmit_to_drv; 770 shdlc->rcv_to_hci = rcv_to_hci; 771 shdlc->tx_headroom = tx_headroom; 772 shdlc->tx_tailroom = tx_tailroom; 773 shdlc->llc_failure = llc_failure; 774 775 return shdlc; 776 } 777 778 static void llc_shdlc_deinit(struct nfc_llc *llc) 779 { 780 struct llc_shdlc *shdlc = nfc_llc_get_data(llc); 781 782 skb_queue_purge(&shdlc->rcv_q); 783 skb_queue_purge(&shdlc->send_q); 784 skb_queue_purge(&shdlc->ack_pending_q); 785 786 kfree(shdlc); 787 } 788 789 static int llc_shdlc_start(struct nfc_llc *llc) 790 { 791 struct llc_shdlc *shdlc = nfc_llc_get_data(llc); 792 793 return llc_shdlc_connect(shdlc); 794 } 795 796 static int llc_shdlc_stop(struct nfc_llc *llc) 797 { 798 struct llc_shdlc *shdlc = nfc_llc_get_data(llc); 799 800 llc_shdlc_disconnect(shdlc); 801 802 return 0; 803 } 804 805 static void llc_shdlc_rcv_from_drv(struct nfc_llc *llc, struct sk_buff *skb) 806 { 807 struct llc_shdlc *shdlc = nfc_llc_get_data(llc); 808 809 llc_shdlc_recv_frame(shdlc, skb); 810 } 811 812 static int llc_shdlc_xmit_from_hci(struct nfc_llc *llc, struct sk_buff *skb) 813 { 814 struct llc_shdlc *shdlc = nfc_llc_get_data(llc); 815 816 skb_queue_tail(&shdlc->send_q, skb); 817 818 schedule_work(&shdlc->sm_work); 819 820 return 0; 821 } 822 823 static const struct nfc_llc_ops llc_shdlc_ops = { 824 .init = llc_shdlc_init, 825 .deinit = llc_shdlc_deinit, 826 .start = llc_shdlc_start, 827 .stop = llc_shdlc_stop, 828 .rcv_from_drv = llc_shdlc_rcv_from_drv, 829 .xmit_from_hci = llc_shdlc_xmit_from_hci, 830 }; 831 832 int nfc_llc_shdlc_register(void) 833 { 834 return nfc_llc_register(LLC_SHDLC_NAME, &llc_shdlc_ops); 835 } 836