1/* 2 * slcan.c - serial line CAN interface driver (using tty line discipline) 3 * 4 * This file is derived from linux/drivers/net/slip/slip.c and got 5 * inspiration from linux/drivers/net/can/can327.c for the rework made 6 * on the line discipline code. 7 * 8 * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk> 9 * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org> 10 * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net> 11 * can327.c Author : Max Staudt <max-linux@enpas.org> 12 * 13 * This program is free software; you can redistribute it and/or modify it 14 * under the terms of the GNU General Public License as published by the 15 * Free Software Foundation; either version 2 of the License, or (at your 16 * option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, but 19 * WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License along 24 * with this program; if not, see http://www.gnu.org/licenses/gpl.html 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 27 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 28 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 29 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 30 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 31 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 32 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 36 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 37 * DAMAGE. 38 * 39 */ 40 41#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 42 43#include <linux/module.h> 44 45#include <linux/uaccess.h> 46#include <linux/bitops.h> 47#include <linux/string.h> 48#include <linux/tty.h> 49#include <linux/errno.h> 50#include <linux/netdevice.h> 51#include <linux/skbuff.h> 52#include <linux/rtnetlink.h> 53#include <linux/init.h> 54#include <linux/kernel.h> 55#include <linux/workqueue.h> 56#include <linux/can.h> 57#include <linux/can/dev.h> 58#include <linux/can/skb.h> 59 60#include "slcan.h" 61 62MODULE_ALIAS_LDISC(N_SLCAN); 63MODULE_DESCRIPTION("serial line CAN interface"); 64MODULE_LICENSE("GPL"); 65MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); 66MODULE_AUTHOR("Dario Binacchi <dario.binacchi@amarulasolutions.com>"); 67 68/* maximum rx buffer len: extended CAN frame with timestamp */ 69#define SLCAN_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1) 70 71#define SLCAN_CMD_LEN 1 72#define SLCAN_SFF_ID_LEN 3 73#define SLCAN_EFF_ID_LEN 8 74#define SLCAN_STATE_LEN 1 75#define SLCAN_STATE_BE_RXCNT_LEN 3 76#define SLCAN_STATE_BE_TXCNT_LEN 3 77#define SLCAN_STATE_FRAME_LEN (1 + SLCAN_CMD_LEN + \ 78 SLCAN_STATE_BE_RXCNT_LEN + \ 79 SLCAN_STATE_BE_TXCNT_LEN) 80struct slcan { 81 struct can_priv can; 82 83 /* Various fields. */ 84 struct tty_struct *tty; /* ptr to TTY structure */ 85 struct net_device *dev; /* easy for intr handling */ 86 spinlock_t lock; 87 struct work_struct tx_work; /* Flushes transmit buffer */ 88 89 /* These are pointers to the malloc()ed frame buffers. */ 90 unsigned char rbuff[SLCAN_MTU]; /* receiver buffer */ 91 int rcount; /* received chars counter */ 92 unsigned char xbuff[SLCAN_MTU]; /* transmitter buffer*/ 93 unsigned char *xhead; /* pointer to next XMIT byte */ 94 int xleft; /* bytes left in XMIT queue */ 95 96 unsigned long flags; /* Flag values/ mode etc */ 97#define SLF_ERROR 0 /* Parity, etc. error */ 98#define SLF_XCMD 1 /* Command transmission */ 99 unsigned long cmd_flags; /* Command flags */ 100#define CF_ERR_RST 0 /* Reset errors on open */ 101 wait_queue_head_t xcmd_wait; /* Wait queue for commands */ 102 /* transmission */ 103}; 104 105static const u32 slcan_bitrate_const[] = { 106 10000, 20000, 50000, 100000, 125000, 107 250000, 500000, 800000, 1000000 108}; 109 110bool slcan_err_rst_on_open(struct net_device *ndev) 111{ 112 struct slcan *sl = netdev_priv(ndev); 113 114 return !!test_bit(CF_ERR_RST, &sl->cmd_flags); 115} 116 117int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on) 118{ 119 struct slcan *sl = netdev_priv(ndev); 120 121 if (netif_running(ndev)) 122 return -EBUSY; 123 124 if (on) 125 set_bit(CF_ERR_RST, &sl->cmd_flags); 126 else 127 clear_bit(CF_ERR_RST, &sl->cmd_flags); 128 129 return 0; 130} 131 132/************************************************************************* 133 * SLCAN ENCAPSULATION FORMAT * 134 *************************************************************************/ 135 136/* A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended 137 * frame format) a data length code (len) which can be from 0 to 8 138 * and up to <len> data bytes as payload. 139 * Additionally a CAN frame may become a remote transmission frame if the 140 * RTR-bit is set. This causes another ECU to send a CAN frame with the 141 * given can_id. 142 * 143 * The SLCAN ASCII representation of these different frame types is: 144 * <type> <id> <dlc> <data>* 145 * 146 * Extended frames (29 bit) are defined by capital characters in the type. 147 * RTR frames are defined as 'r' types - normal frames have 't' type: 148 * t => 11 bit data frame 149 * r => 11 bit RTR frame 150 * T => 29 bit data frame 151 * R => 29 bit RTR frame 152 * 153 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64). 154 * The <dlc> is a one byte ASCII number ('0' - '8') 155 * The <data> section has at much ASCII Hex bytes as defined by the <dlc> 156 * 157 * Examples: 158 * 159 * t1230 : can_id 0x123, len 0, no data 160 * t4563112233 : can_id 0x456, len 3, data 0x11 0x22 0x33 161 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, len 2, data 0xAA 0x55 162 * r1230 : can_id 0x123, len 0, no data, remote transmission request 163 * 164 */ 165 166/************************************************************************* 167 * STANDARD SLCAN DECAPSULATION * 168 *************************************************************************/ 169 170/* Send one completely decapsulated can_frame to the network layer */ 171static void slcan_bump_frame(struct slcan *sl) 172{ 173 struct sk_buff *skb; 174 struct can_frame *cf; 175 int i, tmp; 176 u32 tmpid; 177 char *cmd = sl->rbuff; 178 179 skb = alloc_can_skb(sl->dev, &cf); 180 if (unlikely(!skb)) { 181 sl->dev->stats.rx_dropped++; 182 return; 183 } 184 185 switch (*cmd) { 186 case 'r': 187 cf->can_id = CAN_RTR_FLAG; 188 fallthrough; 189 case 't': 190 /* store dlc ASCII value and terminate SFF CAN ID string */ 191 cf->len = sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN]; 192 sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN] = 0; 193 /* point to payload data behind the dlc */ 194 cmd += SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN + 1; 195 break; 196 case 'R': 197 cf->can_id = CAN_RTR_FLAG; 198 fallthrough; 199 case 'T': 200 cf->can_id |= CAN_EFF_FLAG; 201 /* store dlc ASCII value and terminate EFF CAN ID string */ 202 cf->len = sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN]; 203 sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN] = 0; 204 /* point to payload data behind the dlc */ 205 cmd += SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN + 1; 206 break; 207 default: 208 goto decode_failed; 209 } 210 211 if (kstrtou32(sl->rbuff + SLCAN_CMD_LEN, 16, &tmpid)) 212 goto decode_failed; 213 214 cf->can_id |= tmpid; 215 216 /* get len from sanitized ASCII value */ 217 if (cf->len >= '0' && cf->len < '9') 218 cf->len -= '0'; 219 else 220 goto decode_failed; 221 222 /* RTR frames may have a dlc > 0 but they never have any data bytes */ 223 if (!(cf->can_id & CAN_RTR_FLAG)) { 224 for (i = 0; i < cf->len; i++) { 225 tmp = hex_to_bin(*cmd++); 226 if (tmp < 0) 227 goto decode_failed; 228 229 cf->data[i] = (tmp << 4); 230 tmp = hex_to_bin(*cmd++); 231 if (tmp < 0) 232 goto decode_failed; 233 234 cf->data[i] |= tmp; 235 } 236 } 237 238 sl->dev->stats.rx_packets++; 239 if (!(cf->can_id & CAN_RTR_FLAG)) 240 sl->dev->stats.rx_bytes += cf->len; 241 242 netif_rx(skb); 243 return; 244 245decode_failed: 246 sl->dev->stats.rx_errors++; 247 dev_kfree_skb(skb); 248} 249 250/* A change state frame must contain state info and receive and transmit 251 * error counters. 252 * 253 * Examples: 254 * 255 * sb256256 : state bus-off: rx counter 256, tx counter 256 256 * sa057033 : state active, rx counter 57, tx counter 33 257 */ 258static void slcan_bump_state(struct slcan *sl) 259{ 260 struct net_device *dev = sl->dev; 261 struct sk_buff *skb; 262 struct can_frame *cf; 263 char *cmd = sl->rbuff; 264 u32 rxerr, txerr; 265 enum can_state state, rx_state, tx_state; 266 267 switch (cmd[1]) { 268 case 'a': 269 state = CAN_STATE_ERROR_ACTIVE; 270 break; 271 case 'w': 272 state = CAN_STATE_ERROR_WARNING; 273 break; 274 case 'p': 275 state = CAN_STATE_ERROR_PASSIVE; 276 break; 277 case 'b': 278 state = CAN_STATE_BUS_OFF; 279 break; 280 default: 281 return; 282 } 283 284 if (state == sl->can.state || sl->rcount < SLCAN_STATE_FRAME_LEN) 285 return; 286 287 cmd += SLCAN_STATE_BE_RXCNT_LEN + SLCAN_CMD_LEN + 1; 288 cmd[SLCAN_STATE_BE_TXCNT_LEN] = 0; 289 if (kstrtou32(cmd, 10, &txerr)) 290 return; 291 292 *cmd = 0; 293 cmd -= SLCAN_STATE_BE_RXCNT_LEN; 294 if (kstrtou32(cmd, 10, &rxerr)) 295 return; 296 297 skb = alloc_can_err_skb(dev, &cf); 298 299 tx_state = txerr >= rxerr ? state : 0; 300 rx_state = txerr <= rxerr ? state : 0; 301 can_change_state(dev, cf, tx_state, rx_state); 302 303 if (state == CAN_STATE_BUS_OFF) { 304 can_bus_off(dev); 305 } else if (skb) { 306 cf->can_id |= CAN_ERR_CNT; 307 cf->data[6] = txerr; 308 cf->data[7] = rxerr; 309 } 310 311 if (skb) 312 netif_rx(skb); 313} 314 315/* An error frame can contain more than one type of error. 316 * 317 * Examples: 318 * 319 * e1a : len 1, errors: ACK error 320 * e3bcO: len 3, errors: Bit0 error, CRC error, Tx overrun error 321 */ 322static void slcan_bump_err(struct slcan *sl) 323{ 324 struct net_device *dev = sl->dev; 325 struct sk_buff *skb; 326 struct can_frame *cf; 327 char *cmd = sl->rbuff; 328 bool rx_errors = false, tx_errors = false, rx_over_errors = false; 329 int i, len; 330 331 /* get len from sanitized ASCII value */ 332 len = cmd[1]; 333 if (len >= '0' && len < '9') 334 len -= '0'; 335 else 336 return; 337 338 if ((len + SLCAN_CMD_LEN + 1) > sl->rcount) 339 return; 340 341 skb = alloc_can_err_skb(dev, &cf); 342 343 if (skb) 344 cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; 345 346 cmd += SLCAN_CMD_LEN + 1; 347 for (i = 0; i < len; i++, cmd++) { 348 switch (*cmd) { 349 case 'a': 350 netdev_dbg(dev, "ACK error\n"); 351 tx_errors = true; 352 if (skb) { 353 cf->can_id |= CAN_ERR_ACK; 354 cf->data[3] = CAN_ERR_PROT_LOC_ACK; 355 } 356 357 break; 358 case 'b': 359 netdev_dbg(dev, "Bit0 error\n"); 360 tx_errors = true; 361 if (skb) 362 cf->data[2] |= CAN_ERR_PROT_BIT0; 363 364 break; 365 case 'B': 366 netdev_dbg(dev, "Bit1 error\n"); 367 tx_errors = true; 368 if (skb) 369 cf->data[2] |= CAN_ERR_PROT_BIT1; 370 371 break; 372 case 'c': 373 netdev_dbg(dev, "CRC error\n"); 374 rx_errors = true; 375 if (skb) { 376 cf->data[2] |= CAN_ERR_PROT_BIT; 377 cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ; 378 } 379 380 break; 381 case 'f': 382 netdev_dbg(dev, "Form Error\n"); 383 rx_errors = true; 384 if (skb) 385 cf->data[2] |= CAN_ERR_PROT_FORM; 386 387 break; 388 case 'o': 389 netdev_dbg(dev, "Rx overrun error\n"); 390 rx_over_errors = true; 391 rx_errors = true; 392 if (skb) { 393 cf->can_id |= CAN_ERR_CRTL; 394 cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW; 395 } 396 397 break; 398 case 'O': 399 netdev_dbg(dev, "Tx overrun error\n"); 400 tx_errors = true; 401 if (skb) { 402 cf->can_id |= CAN_ERR_CRTL; 403 cf->data[1] = CAN_ERR_CRTL_TX_OVERFLOW; 404 } 405 406 break; 407 case 's': 408 netdev_dbg(dev, "Stuff error\n"); 409 rx_errors = true; 410 if (skb) 411 cf->data[2] |= CAN_ERR_PROT_STUFF; 412 413 break; 414 default: 415 if (skb) 416 dev_kfree_skb(skb); 417 418 return; 419 } 420 } 421 422 if (rx_errors) 423 dev->stats.rx_errors++; 424 425 if (rx_over_errors) 426 dev->stats.rx_over_errors++; 427 428 if (tx_errors) 429 dev->stats.tx_errors++; 430 431 if (skb) 432 netif_rx(skb); 433} 434 435static void slcan_bump(struct slcan *sl) 436{ 437 switch (sl->rbuff[0]) { 438 case 'r': 439 fallthrough; 440 case 't': 441 fallthrough; 442 case 'R': 443 fallthrough; 444 case 'T': 445 return slcan_bump_frame(sl); 446 case 'e': 447 return slcan_bump_err(sl); 448 case 's': 449 return slcan_bump_state(sl); 450 default: 451 return; 452 } 453} 454 455/* parse tty input stream */ 456static void slcan_unesc(struct slcan *sl, unsigned char s) 457{ 458 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ 459 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 460 sl->rcount > 4) 461 slcan_bump(sl); 462 463 sl->rcount = 0; 464 } else { 465 if (!test_bit(SLF_ERROR, &sl->flags)) { 466 if (sl->rcount < SLCAN_MTU) { 467 sl->rbuff[sl->rcount++] = s; 468 return; 469 } 470 471 sl->dev->stats.rx_over_errors++; 472 set_bit(SLF_ERROR, &sl->flags); 473 } 474 } 475} 476 477/************************************************************************* 478 * STANDARD SLCAN ENCAPSULATION * 479 *************************************************************************/ 480 481/* Encapsulate one can_frame and stuff into a TTY queue. */ 482static void slcan_encaps(struct slcan *sl, struct can_frame *cf) 483{ 484 int actual, i; 485 unsigned char *pos; 486 unsigned char *endpos; 487 canid_t id = cf->can_id; 488 489 pos = sl->xbuff; 490 491 if (cf->can_id & CAN_RTR_FLAG) 492 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */ 493 else 494 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */ 495 496 /* determine number of chars for the CAN-identifier */ 497 if (cf->can_id & CAN_EFF_FLAG) { 498 id &= CAN_EFF_MASK; 499 endpos = pos + SLCAN_EFF_ID_LEN; 500 } else { 501 *pos |= 0x20; /* convert R/T to lower case for SFF */ 502 id &= CAN_SFF_MASK; 503 endpos = pos + SLCAN_SFF_ID_LEN; 504 } 505 506 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */ 507 pos++; 508 while (endpos >= pos) { 509 *endpos-- = hex_asc_upper[id & 0xf]; 510 id >>= 4; 511 } 512 513 pos += (cf->can_id & CAN_EFF_FLAG) ? 514 SLCAN_EFF_ID_LEN : SLCAN_SFF_ID_LEN; 515 516 *pos++ = cf->len + '0'; 517 518 /* RTR frames may have a dlc > 0 but they never have any data bytes */ 519 if (!(cf->can_id & CAN_RTR_FLAG)) { 520 for (i = 0; i < cf->len; i++) 521 pos = hex_byte_pack_upper(pos, cf->data[i]); 522 523 sl->dev->stats.tx_bytes += cf->len; 524 } 525 526 *pos++ = '\r'; 527 528 /* Order of next two lines is *very* important. 529 * When we are sending a little amount of data, 530 * the transfer may be completed inside the ops->write() 531 * routine, because it's running with interrupts enabled. 532 * In this case we *never* got WRITE_WAKEUP event, 533 * if we did not request it before write operation. 534 * 14 Oct 1994 Dmitry Gorodchanin. 535 */ 536 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 537 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff); 538 sl->xleft = (pos - sl->xbuff) - actual; 539 sl->xhead = sl->xbuff + actual; 540} 541 542/* Write out any remaining transmit buffer. Scheduled when tty is writable */ 543static void slcan_transmit(struct work_struct *work) 544{ 545 struct slcan *sl = container_of(work, struct slcan, tx_work); 546 int actual; 547 548 spin_lock_bh(&sl->lock); 549 /* First make sure we're connected. */ 550 if (unlikely(!netif_running(sl->dev)) && 551 likely(!test_bit(SLF_XCMD, &sl->flags))) { 552 spin_unlock_bh(&sl->lock); 553 return; 554 } 555 556 if (sl->xleft <= 0) { 557 if (unlikely(test_bit(SLF_XCMD, &sl->flags))) { 558 clear_bit(SLF_XCMD, &sl->flags); 559 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 560 spin_unlock_bh(&sl->lock); 561 wake_up(&sl->xcmd_wait); 562 return; 563 } 564 565 /* Now serial buffer is almost free & we can start 566 * transmission of another packet 567 */ 568 sl->dev->stats.tx_packets++; 569 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 570 spin_unlock_bh(&sl->lock); 571 netif_wake_queue(sl->dev); 572 return; 573 } 574 575 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft); 576 sl->xleft -= actual; 577 sl->xhead += actual; 578 spin_unlock_bh(&sl->lock); 579} 580 581/* Called by the driver when there's room for more data. 582 * Schedule the transmit. 583 */ 584static void slcan_write_wakeup(struct tty_struct *tty) 585{ 586 struct slcan *sl = tty->disc_data; 587 588 schedule_work(&sl->tx_work); 589} 590 591/* Send a can_frame to a TTY queue. */ 592static netdev_tx_t slcan_netdev_xmit(struct sk_buff *skb, 593 struct net_device *dev) 594{ 595 struct slcan *sl = netdev_priv(dev); 596 597 if (can_dev_dropped_skb(dev, skb)) 598 return NETDEV_TX_OK; 599 600 spin_lock(&sl->lock); 601 if (!netif_running(dev)) { 602 spin_unlock(&sl->lock); 603 netdev_warn(dev, "xmit: iface is down\n"); 604 goto out; 605 } 606 if (!sl->tty) { 607 spin_unlock(&sl->lock); 608 goto out; 609 } 610 611 netif_stop_queue(sl->dev); 612 slcan_encaps(sl, (struct can_frame *)skb->data); /* encaps & send */ 613 spin_unlock(&sl->lock); 614 615 skb_tx_timestamp(skb); 616 617out: 618 kfree_skb(skb); 619 return NETDEV_TX_OK; 620} 621 622/****************************************** 623 * Routines looking at netdevice side. 624 ******************************************/ 625 626static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd) 627{ 628 int ret, actual, n; 629 630 spin_lock(&sl->lock); 631 if (!sl->tty) { 632 spin_unlock(&sl->lock); 633 return -ENODEV; 634 } 635 636 n = scnprintf(sl->xbuff, sizeof(sl->xbuff), "%s", cmd); 637 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 638 actual = sl->tty->ops->write(sl->tty, sl->xbuff, n); 639 sl->xleft = n - actual; 640 sl->xhead = sl->xbuff + actual; 641 set_bit(SLF_XCMD, &sl->flags); 642 spin_unlock(&sl->lock); 643 ret = wait_event_interruptible_timeout(sl->xcmd_wait, 644 !test_bit(SLF_XCMD, &sl->flags), 645 HZ); 646 clear_bit(SLF_XCMD, &sl->flags); 647 if (ret == -ERESTARTSYS) 648 return ret; 649 650 if (ret == 0) 651 return -ETIMEDOUT; 652 653 return 0; 654} 655 656/* Netdevice UP -> DOWN routine */ 657static int slcan_netdev_close(struct net_device *dev) 658{ 659 struct slcan *sl = netdev_priv(dev); 660 int err; 661 662 if (sl->can.bittiming.bitrate && 663 sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { 664 err = slcan_transmit_cmd(sl, "C\r"); 665 if (err) 666 netdev_warn(dev, 667 "failed to send close command 'C\\r'\n"); 668 } 669 670 /* TTY discipline is running. */ 671 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 672 flush_work(&sl->tx_work); 673 674 netif_stop_queue(dev); 675 sl->rcount = 0; 676 sl->xleft = 0; 677 close_candev(dev); 678 sl->can.state = CAN_STATE_STOPPED; 679 if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN) 680 sl->can.bittiming.bitrate = CAN_BITRATE_UNSET; 681 682 return 0; 683} 684 685/* Netdevice DOWN -> UP routine */ 686static int slcan_netdev_open(struct net_device *dev) 687{ 688 struct slcan *sl = netdev_priv(dev); 689 unsigned char cmd[SLCAN_MTU]; 690 int err, s; 691 692 /* The baud rate is not set with the command 693 * `ip link set <iface> type can bitrate <baud>' and therefore 694 * can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing 695 * open_candev() to fail. So let's set to a fake value. 696 */ 697 if (sl->can.bittiming.bitrate == CAN_BITRATE_UNSET) 698 sl->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN; 699 700 err = open_candev(dev); 701 if (err) { 702 netdev_err(dev, "failed to open can device\n"); 703 return err; 704 } 705 706 if (sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { 707 for (s = 0; s < ARRAY_SIZE(slcan_bitrate_const); s++) { 708 if (sl->can.bittiming.bitrate == slcan_bitrate_const[s]) 709 break; 710 } 711 712 /* The CAN framework has already validate the bitrate value, 713 * so we can avoid to check if `s' has been properly set. 714 */ 715 snprintf(cmd, sizeof(cmd), "C\rS%d\r", s); 716 err = slcan_transmit_cmd(sl, cmd); 717 if (err) { 718 netdev_err(dev, 719 "failed to send bitrate command 'C\\rS%d\\r'\n", 720 s); 721 goto cmd_transmit_failed; 722 } 723 724 if (test_bit(CF_ERR_RST, &sl->cmd_flags)) { 725 err = slcan_transmit_cmd(sl, "F\r"); 726 if (err) { 727 netdev_err(dev, 728 "failed to send error command 'F\\r'\n"); 729 goto cmd_transmit_failed; 730 } 731 } 732 733 if (sl->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) { 734 err = slcan_transmit_cmd(sl, "L\r"); 735 if (err) { 736 netdev_err(dev, 737 "failed to send listen-only command 'L\\r'\n"); 738 goto cmd_transmit_failed; 739 } 740 } else { 741 err = slcan_transmit_cmd(sl, "O\r"); 742 if (err) { 743 netdev_err(dev, 744 "failed to send open command 'O\\r'\n"); 745 goto cmd_transmit_failed; 746 } 747 } 748 } 749 750 sl->can.state = CAN_STATE_ERROR_ACTIVE; 751 netif_start_queue(dev); 752 return 0; 753 754cmd_transmit_failed: 755 close_candev(dev); 756 return err; 757} 758 759static const struct net_device_ops slcan_netdev_ops = { 760 .ndo_open = slcan_netdev_open, 761 .ndo_stop = slcan_netdev_close, 762 .ndo_start_xmit = slcan_netdev_xmit, 763 .ndo_change_mtu = can_change_mtu, 764}; 765 766/****************************************** 767 * Routines looking at TTY side. 768 ******************************************/ 769 770/* Handle the 'receiver data ready' interrupt. 771 * This function is called by the 'tty_io' module in the kernel when 772 * a block of SLCAN data has been received, which can now be decapsulated 773 * and sent on to some IP layer for further processing. This will not 774 * be re-entered while running but other ldisc functions may be called 775 * in parallel 776 */ 777static void slcan_receive_buf(struct tty_struct *tty, const u8 *cp, 778 const u8 *fp, size_t count) 779{ 780 struct slcan *sl = tty->disc_data; 781 782 if (!netif_running(sl->dev)) 783 return; 784 785 /* Read the characters out of the buffer */ 786 while (count--) { 787 if (fp && *fp++) { 788 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) 789 sl->dev->stats.rx_errors++; 790 cp++; 791 continue; 792 } 793 slcan_unesc(sl, *cp++); 794 } 795} 796 797/* Open the high-level part of the SLCAN channel. 798 * This function is called by the TTY module when the 799 * SLCAN line discipline is called for. 800 * 801 * Called in process context serialized from other ldisc calls. 802 */ 803static int slcan_open(struct tty_struct *tty) 804{ 805 struct net_device *dev; 806 struct slcan *sl; 807 int err; 808 809 if (!capable(CAP_NET_ADMIN)) 810 return -EPERM; 811 812 if (!tty->ops->write) 813 return -EOPNOTSUPP; 814 815 dev = alloc_candev(sizeof(*sl), 1); 816 if (!dev) 817 return -ENFILE; 818 819 sl = netdev_priv(dev); 820 821 /* Configure TTY interface */ 822 tty->receive_room = 65536; /* We don't flow control */ 823 sl->rcount = 0; 824 sl->xleft = 0; 825 spin_lock_init(&sl->lock); 826 INIT_WORK(&sl->tx_work, slcan_transmit); 827 init_waitqueue_head(&sl->xcmd_wait); 828 829 /* Configure CAN metadata */ 830 sl->can.bitrate_const = slcan_bitrate_const; 831 sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const); 832 sl->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY; 833 834 /* Configure netdev interface */ 835 sl->dev = dev; 836 dev->netdev_ops = &slcan_netdev_ops; 837 dev->ethtool_ops = &slcan_ethtool_ops; 838 839 /* Mark ldisc channel as alive */ 840 sl->tty = tty; 841 tty->disc_data = sl; 842 843 err = register_candev(dev); 844 if (err) { 845 free_candev(dev); 846 pr_err("can't register candev\n"); 847 return err; 848 } 849 850 netdev_info(dev, "slcan on %s.\n", tty->name); 851 /* TTY layer expects 0 on success */ 852 return 0; 853} 854 855/* Close down a SLCAN channel. 856 * This means flushing out any pending queues, and then returning. This 857 * call is serialized against other ldisc functions. 858 * Once this is called, no other ldisc function of ours is entered. 859 * 860 * We also use this method for a hangup event. 861 */ 862static void slcan_close(struct tty_struct *tty) 863{ 864 struct slcan *sl = tty->disc_data; 865 866 unregister_candev(sl->dev); 867 868 /* 869 * The netdev needn't be UP (so .ndo_stop() is not called). Hence make 870 * sure this is not running before freeing it up. 871 */ 872 flush_work(&sl->tx_work); 873 874 /* Mark channel as dead */ 875 spin_lock_bh(&sl->lock); 876 tty->disc_data = NULL; 877 sl->tty = NULL; 878 spin_unlock_bh(&sl->lock); 879 880 netdev_info(sl->dev, "slcan off %s.\n", tty->name); 881 free_candev(sl->dev); 882} 883 884/* Perform I/O control on an active SLCAN channel. */ 885static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd, 886 unsigned long arg) 887{ 888 struct slcan *sl = tty->disc_data; 889 unsigned int tmp; 890 891 switch (cmd) { 892 case SIOCGIFNAME: 893 tmp = strlen(sl->dev->name) + 1; 894 if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) 895 return -EFAULT; 896 return 0; 897 898 case SIOCSIFHWADDR: 899 return -EINVAL; 900 901 default: 902 return tty_mode_ioctl(tty, cmd, arg); 903 } 904} 905 906static struct tty_ldisc_ops slcan_ldisc = { 907 .owner = THIS_MODULE, 908 .num = N_SLCAN, 909 .name = KBUILD_MODNAME, 910 .open = slcan_open, 911 .close = slcan_close, 912 .ioctl = slcan_ioctl, 913 .receive_buf = slcan_receive_buf, 914 .write_wakeup = slcan_write_wakeup, 915}; 916 917static int __init slcan_init(void) 918{ 919 int status; 920 921 pr_info("serial line CAN interface driver\n"); 922 923 /* Fill in our line protocol discipline, and register it */ 924 status = tty_register_ldisc(&slcan_ldisc); 925 if (status) 926 pr_err("can't register line discipline\n"); 927 928 return status; 929} 930 931static void __exit slcan_exit(void) 932{ 933 /* This will only be called when all channels have been closed by 934 * userspace - tty_ldisc.c takes care of the module's refcount. 935 */ 936 tty_unregister_ldisc(&slcan_ldisc); 937} 938 939module_init(slcan_init); 940module_exit(slcan_exit); 941