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_DATA_LENGTH_LEN 1
75#define SLCAN_ERROR_LEN 1
76#define SLCAN_STATE_LEN 1
77#define SLCAN_STATE_BE_RXCNT_LEN 3
78#define SLCAN_STATE_BE_TXCNT_LEN 3
79#define SLCAN_STATE_MSG_LEN (SLCAN_CMD_LEN + \
80 SLCAN_STATE_LEN + \
81 SLCAN_STATE_BE_RXCNT_LEN + \
82 SLCAN_STATE_BE_TXCNT_LEN)
83#define SLCAN_ERROR_MSG_LEN_MIN (SLCAN_CMD_LEN + \
84 SLCAN_ERROR_LEN + \
85 SLCAN_DATA_LENGTH_LEN)
86#define SLCAN_FRAME_MSG_LEN_MIN (SLCAN_CMD_LEN + \
87 SLCAN_SFF_ID_LEN + \
88 SLCAN_DATA_LENGTH_LEN)
89struct slcan {
90 struct can_priv can;
91
92 /* Various fields. */
93 struct tty_struct *tty; /* ptr to TTY structure */
94 struct net_device *dev; /* easy for intr handling */
95 spinlock_t lock;
96 struct work_struct tx_work; /* Flushes transmit buffer */
97
98 /* These are pointers to the malloc()ed frame buffers. */
99 unsigned char rbuff[SLCAN_MTU]; /* receiver buffer */
100 int rcount; /* received chars counter */
101 unsigned char xbuff[SLCAN_MTU]; /* transmitter buffer*/
102 unsigned char *xhead; /* pointer to next XMIT byte */
103 int xleft; /* bytes left in XMIT queue */
104
105 unsigned long flags; /* Flag values/ mode etc */
106#define SLF_ERROR 0 /* Parity, etc. error */
107#define SLF_XCMD 1 /* Command transmission */
108 unsigned long cmd_flags; /* Command flags */
109#define CF_ERR_RST 0 /* Reset errors on open */
110 wait_queue_head_t xcmd_wait; /* Wait queue for commands */
111 /* transmission */
112};
113
114static const u32 slcan_bitrate_const[] = {
115 10000, 20000, 50000, 100000, 125000,
116 250000, 500000, 800000, 1000000
117};
118
119bool slcan_err_rst_on_open(struct net_device *ndev)
120{
121 struct slcan *sl = netdev_priv(dev: ndev);
122
123 return !!test_bit(CF_ERR_RST, &sl->cmd_flags);
124}
125
126int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on)
127{
128 struct slcan *sl = netdev_priv(dev: ndev);
129
130 if (netif_running(dev: ndev))
131 return -EBUSY;
132
133 if (on)
134 set_bit(CF_ERR_RST, addr: &sl->cmd_flags);
135 else
136 clear_bit(CF_ERR_RST, addr: &sl->cmd_flags);
137
138 return 0;
139}
140
141/*************************************************************************
142 * SLCAN ENCAPSULATION FORMAT *
143 *************************************************************************/
144
145/* A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
146 * frame format) a data length code (len) which can be from 0 to 8
147 * and up to <len> data bytes as payload.
148 * Additionally a CAN frame may become a remote transmission frame if the
149 * RTR-bit is set. This causes another ECU to send a CAN frame with the
150 * given can_id.
151 *
152 * The SLCAN ASCII representation of these different frame types is:
153 * <type> <id> <dlc> <data>*
154 *
155 * Extended frames (29 bit) are defined by capital characters in the type.
156 * RTR frames are defined as 'r' types - normal frames have 't' type:
157 * t => 11 bit data frame
158 * r => 11 bit RTR frame
159 * T => 29 bit data frame
160 * R => 29 bit RTR frame
161 *
162 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
163 * The <dlc> is a one byte ASCII number ('0' - '8')
164 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
165 *
166 * Examples:
167 *
168 * t1230 : can_id 0x123, len 0, no data
169 * t4563112233 : can_id 0x456, len 3, data 0x11 0x22 0x33
170 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, len 2, data 0xAA 0x55
171 * r1230 : can_id 0x123, len 0, no data, remote transmission request
172 *
173 */
174
175/*************************************************************************
176 * STANDARD SLCAN DECAPSULATION *
177 *************************************************************************/
178
179/* Send one completely decapsulated can_frame to the network layer */
180static void slcan_bump_frame(struct slcan *sl)
181{
182 struct sk_buff *skb;
183 struct can_frame *cf;
184 int i, tmp;
185 u32 tmpid;
186 char *cmd = sl->rbuff;
187
188 if (sl->rcount < SLCAN_FRAME_MSG_LEN_MIN)
189 return;
190
191 skb = alloc_can_skb(dev: sl->dev, cf: &cf);
192 if (unlikely(!skb)) {
193 sl->dev->stats.rx_dropped++;
194 return;
195 }
196
197 switch (*cmd) {
198 case 'r':
199 cf->can_id = CAN_RTR_FLAG;
200 fallthrough;
201 case 't':
202 /* store dlc ASCII value and terminate SFF CAN ID string */
203 cf->len = sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN];
204 sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN] = 0;
205 /* point to payload data behind the dlc */
206 cmd += SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN + 1;
207 break;
208 case 'R':
209 cf->can_id = CAN_RTR_FLAG;
210 fallthrough;
211 case 'T':
212 cf->can_id |= CAN_EFF_FLAG;
213 /* store dlc ASCII value and terminate EFF CAN ID string */
214 cf->len = sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN];
215 sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN] = 0;
216 /* point to payload data behind the dlc */
217 cmd += SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN + 1;
218 break;
219 default:
220 goto decode_failed;
221 }
222
223 if (kstrtou32(s: sl->rbuff + SLCAN_CMD_LEN, base: 16, res: &tmpid))
224 goto decode_failed;
225
226 cf->can_id |= tmpid;
227
228 /* get len from sanitized ASCII value */
229 if (cf->len >= '0' && cf->len < '9')
230 cf->len -= '0';
231 else
232 goto decode_failed;
233
234 /* RTR frames may have a dlc > 0 but they never have any data bytes */
235 if (!(cf->can_id & CAN_RTR_FLAG)) {
236 for (i = 0; i < cf->len; i++) {
237 tmp = hex_to_bin(ch: *cmd++);
238 if (tmp < 0)
239 goto decode_failed;
240
241 cf->data[i] = (tmp << 4);
242 tmp = hex_to_bin(ch: *cmd++);
243 if (tmp < 0)
244 goto decode_failed;
245
246 cf->data[i] |= tmp;
247 }
248 }
249
250 sl->dev->stats.rx_packets++;
251 if (!(cf->can_id & CAN_RTR_FLAG))
252 sl->dev->stats.rx_bytes += cf->len;
253
254 netif_rx(skb);
255 return;
256
257decode_failed:
258 sl->dev->stats.rx_errors++;
259 dev_kfree_skb(skb);
260}
261
262/* A change state frame must contain state info and receive and transmit
263 * error counters.
264 *
265 * Examples:
266 *
267 * sb256256 : state bus-off: rx counter 256, tx counter 256
268 * sa057033 : state active, rx counter 57, tx counter 33
269 */
270static void slcan_bump_state(struct slcan *sl)
271{
272 struct net_device *dev = sl->dev;
273 struct sk_buff *skb;
274 struct can_frame *cf;
275 char *cmd = sl->rbuff;
276 u32 rxerr, txerr;
277 enum can_state state, rx_state, tx_state;
278
279 switch (cmd[1]) {
280 case 'a':
281 state = CAN_STATE_ERROR_ACTIVE;
282 break;
283 case 'w':
284 state = CAN_STATE_ERROR_WARNING;
285 break;
286 case 'p':
287 state = CAN_STATE_ERROR_PASSIVE;
288 break;
289 case 'b':
290 state = CAN_STATE_BUS_OFF;
291 break;
292 default:
293 return;
294 }
295
296 if (state == sl->can.state || sl->rcount != SLCAN_STATE_MSG_LEN)
297 return;
298
299 cmd += SLCAN_STATE_BE_RXCNT_LEN + SLCAN_CMD_LEN + 1;
300 cmd[SLCAN_STATE_BE_TXCNT_LEN] = 0;
301 if (kstrtou32(s: cmd, base: 10, res: &txerr))
302 return;
303
304 *cmd = 0;
305 cmd -= SLCAN_STATE_BE_RXCNT_LEN;
306 if (kstrtou32(s: cmd, base: 10, res: &rxerr))
307 return;
308
309 skb = alloc_can_err_skb(dev, cf: &cf);
310
311 tx_state = txerr >= rxerr ? state : 0;
312 rx_state = txerr <= rxerr ? state : 0;
313 can_change_state(dev, cf, tx_state, rx_state);
314
315 if (state == CAN_STATE_BUS_OFF) {
316 can_bus_off(dev);
317 } else if (skb) {
318 cf->can_id |= CAN_ERR_CNT;
319 cf->data[6] = txerr;
320 cf->data[7] = rxerr;
321 }
322
323 if (skb)
324 netif_rx(skb);
325}
326
327/* An error frame can contain more than one type of error.
328 *
329 * Examples:
330 *
331 * e1a : len 1, errors: ACK error
332 * e3bcO: len 3, errors: Bit0 error, CRC error, Tx overrun error
333 */
334static void slcan_bump_err(struct slcan *sl)
335{
336 struct net_device *dev = sl->dev;
337 struct sk_buff *skb;
338 struct can_frame *cf;
339 char *cmd = sl->rbuff;
340 bool rx_errors = false, tx_errors = false, rx_over_errors = false;
341 int i, len;
342
343 if (sl->rcount < SLCAN_ERROR_MSG_LEN_MIN)
344 return;
345
346 /* get len from sanitized ASCII value */
347 len = cmd[1];
348 if (len >= '0' && len < '9')
349 len -= '0';
350 else
351 return;
352
353 if ((len + SLCAN_CMD_LEN + 1) > sl->rcount)
354 return;
355
356 skb = alloc_can_err_skb(dev, cf: &cf);
357
358 if (skb)
359 cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
360
361 cmd += SLCAN_CMD_LEN + 1;
362 for (i = 0; i < len; i++, cmd++) {
363 switch (*cmd) {
364 case 'a':
365 netdev_dbg(dev, "ACK error\n");
366 tx_errors = true;
367 if (skb) {
368 cf->can_id |= CAN_ERR_ACK;
369 cf->data[3] = CAN_ERR_PROT_LOC_ACK;
370 }
371
372 break;
373 case 'b':
374 netdev_dbg(dev, "Bit0 error\n");
375 tx_errors = true;
376 if (skb)
377 cf->data[2] |= CAN_ERR_PROT_BIT0;
378
379 break;
380 case 'B':
381 netdev_dbg(dev, "Bit1 error\n");
382 tx_errors = true;
383 if (skb)
384 cf->data[2] |= CAN_ERR_PROT_BIT1;
385
386 break;
387 case 'c':
388 netdev_dbg(dev, "CRC error\n");
389 rx_errors = true;
390 if (skb) {
391 cf->data[2] |= CAN_ERR_PROT_BIT;
392 cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
393 }
394
395 break;
396 case 'f':
397 netdev_dbg(dev, "Form Error\n");
398 rx_errors = true;
399 if (skb)
400 cf->data[2] |= CAN_ERR_PROT_FORM;
401
402 break;
403 case 'o':
404 netdev_dbg(dev, "Rx overrun error\n");
405 rx_over_errors = true;
406 rx_errors = true;
407 if (skb) {
408 cf->can_id |= CAN_ERR_CRTL;
409 cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
410 }
411
412 break;
413 case 'O':
414 netdev_dbg(dev, "Tx overrun error\n");
415 tx_errors = true;
416 if (skb) {
417 cf->can_id |= CAN_ERR_CRTL;
418 cf->data[1] = CAN_ERR_CRTL_TX_OVERFLOW;
419 }
420
421 break;
422 case 's':
423 netdev_dbg(dev, "Stuff error\n");
424 rx_errors = true;
425 if (skb)
426 cf->data[2] |= CAN_ERR_PROT_STUFF;
427
428 break;
429 default:
430 if (skb)
431 dev_kfree_skb(skb);
432
433 return;
434 }
435 }
436
437 if (rx_errors)
438 dev->stats.rx_errors++;
439
440 if (rx_over_errors)
441 dev->stats.rx_over_errors++;
442
443 if (tx_errors)
444 dev->stats.tx_errors++;
445
446 if (skb)
447 netif_rx(skb);
448}
449
450static void slcan_bump(struct slcan *sl)
451{
452 switch (sl->rbuff[0]) {
453 case 'r':
454 fallthrough;
455 case 't':
456 fallthrough;
457 case 'R':
458 fallthrough;
459 case 'T':
460 return slcan_bump_frame(sl);
461 case 'e':
462 return slcan_bump_err(sl);
463 case 's':
464 return slcan_bump_state(sl);
465 default:
466 return;
467 }
468}
469
470/* parse tty input stream */
471static void slcan_unesc(struct slcan *sl, unsigned char s)
472{
473 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
474 if (!test_and_clear_bit(SLF_ERROR, addr: &sl->flags))
475 slcan_bump(sl);
476
477 sl->rcount = 0;
478 } else {
479 if (!test_bit(SLF_ERROR, &sl->flags)) {
480 if (sl->rcount < SLCAN_MTU) {
481 sl->rbuff[sl->rcount++] = s;
482 return;
483 }
484
485 sl->dev->stats.rx_over_errors++;
486 set_bit(SLF_ERROR, addr: &sl->flags);
487 }
488 }
489}
490
491/*************************************************************************
492 * STANDARD SLCAN ENCAPSULATION *
493 *************************************************************************/
494
495/* Encapsulate one can_frame and stuff into a TTY queue. */
496static void slcan_encaps(struct slcan *sl, struct can_frame *cf)
497{
498 int actual, i;
499 unsigned char *pos;
500 unsigned char *endpos;
501 canid_t id = cf->can_id;
502
503 pos = sl->xbuff;
504
505 if (cf->can_id & CAN_RTR_FLAG)
506 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
507 else
508 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
509
510 /* determine number of chars for the CAN-identifier */
511 if (cf->can_id & CAN_EFF_FLAG) {
512 id &= CAN_EFF_MASK;
513 endpos = pos + SLCAN_EFF_ID_LEN;
514 } else {
515 *pos |= 0x20; /* convert R/T to lower case for SFF */
516 id &= CAN_SFF_MASK;
517 endpos = pos + SLCAN_SFF_ID_LEN;
518 }
519
520 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
521 pos++;
522 while (endpos >= pos) {
523 *endpos-- = hex_asc_upper[id & 0xf];
524 id >>= 4;
525 }
526
527 pos += (cf->can_id & CAN_EFF_FLAG) ?
528 SLCAN_EFF_ID_LEN : SLCAN_SFF_ID_LEN;
529
530 *pos++ = cf->len + '0';
531
532 /* RTR frames may have a dlc > 0 but they never have any data bytes */
533 if (!(cf->can_id & CAN_RTR_FLAG)) {
534 for (i = 0; i < cf->len; i++)
535 pos = hex_byte_pack_upper(buf: pos, byte: cf->data[i]);
536
537 sl->dev->stats.tx_bytes += cf->len;
538 }
539
540 *pos++ = '\r';
541
542 /* Order of next two lines is *very* important.
543 * When we are sending a little amount of data,
544 * the transfer may be completed inside the ops->write()
545 * routine, because it's running with interrupts enabled.
546 * In this case we *never* got WRITE_WAKEUP event,
547 * if we did not request it before write operation.
548 * 14 Oct 1994 Dmitry Gorodchanin.
549 */
550 set_bit(nr: TTY_DO_WRITE_WAKEUP, addr: &sl->tty->flags);
551 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
552 sl->xleft = (pos - sl->xbuff) - actual;
553 sl->xhead = sl->xbuff + actual;
554}
555
556/* Write out any remaining transmit buffer. Scheduled when tty is writable */
557static void slcan_transmit(struct work_struct *work)
558{
559 struct slcan *sl = container_of(work, struct slcan, tx_work);
560 int actual;
561
562 spin_lock_bh(lock: &sl->lock);
563 /* First make sure we're connected. */
564 if (unlikely(!netif_running(sl->dev)) &&
565 likely(!test_bit(SLF_XCMD, &sl->flags))) {
566 spin_unlock_bh(lock: &sl->lock);
567 return;
568 }
569
570 if (sl->xleft <= 0) {
571 if (unlikely(test_bit(SLF_XCMD, &sl->flags))) {
572 clear_bit(SLF_XCMD, addr: &sl->flags);
573 clear_bit(nr: TTY_DO_WRITE_WAKEUP, addr: &sl->tty->flags);
574 spin_unlock_bh(lock: &sl->lock);
575 wake_up(&sl->xcmd_wait);
576 return;
577 }
578
579 /* Now serial buffer is almost free & we can start
580 * transmission of another packet
581 */
582 sl->dev->stats.tx_packets++;
583 clear_bit(nr: TTY_DO_WRITE_WAKEUP, addr: &sl->tty->flags);
584 spin_unlock_bh(lock: &sl->lock);
585 netif_wake_queue(dev: sl->dev);
586 return;
587 }
588
589 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
590 sl->xleft -= actual;
591 sl->xhead += actual;
592 spin_unlock_bh(lock: &sl->lock);
593}
594
595/* Called by the driver when there's room for more data.
596 * Schedule the transmit.
597 */
598static void slcan_write_wakeup(struct tty_struct *tty)
599{
600 struct slcan *sl = tty->disc_data;
601
602 schedule_work(work: &sl->tx_work);
603}
604
605/* Send a can_frame to a TTY queue. */
606static netdev_tx_t slcan_netdev_xmit(struct sk_buff *skb,
607 struct net_device *dev)
608{
609 struct slcan *sl = netdev_priv(dev);
610
611 if (can_dev_dropped_skb(dev, skb))
612 return NETDEV_TX_OK;
613
614 spin_lock(lock: &sl->lock);
615 if (!netif_running(dev)) {
616 spin_unlock(lock: &sl->lock);
617 netdev_warn(dev, format: "xmit: iface is down\n");
618 goto out;
619 }
620 if (!sl->tty) {
621 spin_unlock(lock: &sl->lock);
622 goto out;
623 }
624
625 netif_stop_queue(dev: sl->dev);
626 slcan_encaps(sl, cf: (struct can_frame *)skb->data); /* encaps & send */
627 spin_unlock(lock: &sl->lock);
628
629 skb_tx_timestamp(skb);
630
631out:
632 kfree_skb(skb);
633 return NETDEV_TX_OK;
634}
635
636/******************************************
637 * Routines looking at netdevice side.
638 ******************************************/
639
640static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd)
641{
642 int ret, actual, n;
643
644 spin_lock(lock: &sl->lock);
645 if (!sl->tty) {
646 spin_unlock(lock: &sl->lock);
647 return -ENODEV;
648 }
649
650 n = scnprintf(buf: sl->xbuff, size: sizeof(sl->xbuff), fmt: "%s", cmd);
651 set_bit(nr: TTY_DO_WRITE_WAKEUP, addr: &sl->tty->flags);
652 actual = sl->tty->ops->write(sl->tty, sl->xbuff, n);
653 sl->xleft = n - actual;
654 sl->xhead = sl->xbuff + actual;
655 set_bit(SLF_XCMD, addr: &sl->flags);
656 spin_unlock(lock: &sl->lock);
657 ret = wait_event_interruptible_timeout(sl->xcmd_wait,
658 !test_bit(SLF_XCMD, &sl->flags),
659 HZ);
660 clear_bit(SLF_XCMD, addr: &sl->flags);
661 if (ret == -ERESTARTSYS)
662 return ret;
663
664 if (ret == 0)
665 return -ETIMEDOUT;
666
667 return 0;
668}
669
670/* Netdevice UP -> DOWN routine */
671static int slcan_netdev_close(struct net_device *dev)
672{
673 struct slcan *sl = netdev_priv(dev);
674 int err;
675
676 if (sl->can.bittiming.bitrate &&
677 sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
678 err = slcan_transmit_cmd(sl, cmd: "C\r");
679 if (err)
680 netdev_warn(dev,
681 format: "failed to send close command 'C\\r'\n");
682 }
683
684 /* TTY discipline is running. */
685 clear_bit(nr: TTY_DO_WRITE_WAKEUP, addr: &sl->tty->flags);
686 flush_work(work: &sl->tx_work);
687
688 netif_stop_queue(dev);
689 sl->rcount = 0;
690 sl->xleft = 0;
691 close_candev(dev);
692 sl->can.state = CAN_STATE_STOPPED;
693 if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN)
694 sl->can.bittiming.bitrate = CAN_BITRATE_UNSET;
695
696 return 0;
697}
698
699/* Netdevice DOWN -> UP routine */
700static int slcan_netdev_open(struct net_device *dev)
701{
702 struct slcan *sl = netdev_priv(dev);
703 unsigned char cmd[SLCAN_MTU];
704 int err, s;
705
706 /* The baud rate is not set with the command
707 * `ip link set <iface> type can bitrate <baud>' and therefore
708 * can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing
709 * open_candev() to fail. So let's set to a fake value.
710 */
711 if (sl->can.bittiming.bitrate == CAN_BITRATE_UNSET)
712 sl->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN;
713
714 err = open_candev(dev);
715 if (err) {
716 netdev_err(dev, format: "failed to open can device\n");
717 return err;
718 }
719
720 if (sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
721 for (s = 0; s < ARRAY_SIZE(slcan_bitrate_const); s++) {
722 if (sl->can.bittiming.bitrate == slcan_bitrate_const[s])
723 break;
724 }
725
726 /* The CAN framework has already validate the bitrate value,
727 * so we can avoid to check if `s' has been properly set.
728 */
729 snprintf(buf: cmd, size: sizeof(cmd), fmt: "C\rS%d\r", s);
730 err = slcan_transmit_cmd(sl, cmd);
731 if (err) {
732 netdev_err(dev,
733 format: "failed to send bitrate command 'C\\rS%d\\r'\n",
734 s);
735 goto cmd_transmit_failed;
736 }
737
738 if (test_bit(CF_ERR_RST, &sl->cmd_flags)) {
739 err = slcan_transmit_cmd(sl, cmd: "F\r");
740 if (err) {
741 netdev_err(dev,
742 format: "failed to send error command 'F\\r'\n");
743 goto cmd_transmit_failed;
744 }
745 }
746
747 if (sl->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
748 err = slcan_transmit_cmd(sl, cmd: "L\r");
749 if (err) {
750 netdev_err(dev,
751 format: "failed to send listen-only command 'L\\r'\n");
752 goto cmd_transmit_failed;
753 }
754 } else {
755 err = slcan_transmit_cmd(sl, cmd: "O\r");
756 if (err) {
757 netdev_err(dev,
758 format: "failed to send open command 'O\\r'\n");
759 goto cmd_transmit_failed;
760 }
761 }
762 }
763
764 sl->can.state = CAN_STATE_ERROR_ACTIVE;
765 netif_start_queue(dev);
766 return 0;
767
768cmd_transmit_failed:
769 close_candev(dev);
770 return err;
771}
772
773static const struct net_device_ops slcan_netdev_ops = {
774 .ndo_open = slcan_netdev_open,
775 .ndo_stop = slcan_netdev_close,
776 .ndo_start_xmit = slcan_netdev_xmit,
777 .ndo_change_mtu = can_change_mtu,
778};
779
780/******************************************
781 * Routines looking at TTY side.
782 ******************************************/
783
784/* Handle the 'receiver data ready' interrupt.
785 * This function is called by the 'tty_io' module in the kernel when
786 * a block of SLCAN data has been received, which can now be decapsulated
787 * and sent on to some IP layer for further processing. This will not
788 * be re-entered while running but other ldisc functions may be called
789 * in parallel
790 */
791static void slcan_receive_buf(struct tty_struct *tty, const u8 *cp,
792 const u8 *fp, size_t count)
793{
794 struct slcan *sl = tty->disc_data;
795
796 if (!netif_running(dev: sl->dev))
797 return;
798
799 /* Read the characters out of the buffer */
800 while (count--) {
801 if (fp && *fp++) {
802 if (!test_and_set_bit(SLF_ERROR, addr: &sl->flags))
803 sl->dev->stats.rx_errors++;
804 cp++;
805 continue;
806 }
807 slcan_unesc(sl, s: *cp++);
808 }
809}
810
811/* Open the high-level part of the SLCAN channel.
812 * This function is called by the TTY module when the
813 * SLCAN line discipline is called for.
814 *
815 * Called in process context serialized from other ldisc calls.
816 */
817static int slcan_open(struct tty_struct *tty)
818{
819 struct net_device *dev;
820 struct slcan *sl;
821 int err;
822
823 if (!capable(CAP_NET_ADMIN))
824 return -EPERM;
825
826 if (!tty->ops->write)
827 return -EOPNOTSUPP;
828
829 dev = alloc_candev(sizeof(*sl), 1);
830 if (!dev)
831 return -ENFILE;
832
833 sl = netdev_priv(dev);
834
835 /* Configure TTY interface */
836 tty->receive_room = 65536; /* We don't flow control */
837 sl->rcount = 0;
838 sl->xleft = 0;
839 spin_lock_init(&sl->lock);
840 INIT_WORK(&sl->tx_work, slcan_transmit);
841 init_waitqueue_head(&sl->xcmd_wait);
842
843 /* Configure CAN metadata */
844 sl->can.bitrate_const = slcan_bitrate_const;
845 sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
846 sl->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
847
848 /* Configure netdev interface */
849 sl->dev = dev;
850 dev->netdev_ops = &slcan_netdev_ops;
851 dev->ethtool_ops = &slcan_ethtool_ops;
852
853 /* Mark ldisc channel as alive */
854 sl->tty = tty;
855 tty->disc_data = sl;
856
857 err = register_candev(dev);
858 if (err) {
859 free_candev(dev);
860 pr_err("can't register candev\n");
861 return err;
862 }
863
864 netdev_info(dev, format: "slcan on %s.\n", tty->name);
865 /* TTY layer expects 0 on success */
866 return 0;
867}
868
869/* Close down a SLCAN channel.
870 * This means flushing out any pending queues, and then returning. This
871 * call is serialized against other ldisc functions.
872 * Once this is called, no other ldisc function of ours is entered.
873 *
874 * We also use this method for a hangup event.
875 */
876static void slcan_close(struct tty_struct *tty)
877{
878 struct slcan *sl = tty->disc_data;
879
880 unregister_candev(dev: sl->dev);
881
882 /*
883 * The netdev needn't be UP (so .ndo_stop() is not called). Hence make
884 * sure this is not running before freeing it up.
885 */
886 flush_work(work: &sl->tx_work);
887
888 /* Mark channel as dead */
889 spin_lock_bh(lock: &sl->lock);
890 tty->disc_data = NULL;
891 sl->tty = NULL;
892 spin_unlock_bh(lock: &sl->lock);
893
894 netdev_info(dev: sl->dev, format: "slcan off %s.\n", tty->name);
895 free_candev(dev: sl->dev);
896}
897
898/* Perform I/O control on an active SLCAN channel. */
899static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd,
900 unsigned long arg)
901{
902 struct slcan *sl = tty->disc_data;
903 unsigned int tmp;
904
905 switch (cmd) {
906 case SIOCGIFNAME:
907 tmp = strlen(sl->dev->name) + 1;
908 if (copy_to_user(to: (void __user *)arg, from: sl->dev->name, n: tmp))
909 return -EFAULT;
910 return 0;
911
912 case SIOCSIFHWADDR:
913 return -EINVAL;
914
915 default:
916 return tty_mode_ioctl(tty, cmd, arg);
917 }
918}
919
920static struct tty_ldisc_ops slcan_ldisc = {
921 .owner = THIS_MODULE,
922 .num = N_SLCAN,
923 .name = KBUILD_MODNAME,
924 .open = slcan_open,
925 .close = slcan_close,
926 .ioctl = slcan_ioctl,
927 .receive_buf = slcan_receive_buf,
928 .write_wakeup = slcan_write_wakeup,
929};
930
931static int __init slcan_init(void)
932{
933 int status;
934
935 pr_info("serial line CAN interface driver\n");
936
937 /* Fill in our line protocol discipline, and register it */
938 status = tty_register_ldisc(new_ldisc: &slcan_ldisc);
939 if (status)
940 pr_err("can't register line discipline\n");
941
942 return status;
943}
944
945static void __exit slcan_exit(void)
946{
947 /* This will only be called when all channels have been closed by
948 * userspace - tty_ldisc.c takes care of the module's refcount.
949 */
950 tty_unregister_ldisc(ldisc: &slcan_ldisc);
951}
952
953module_init(slcan_init);
954module_exit(slcan_exit);
955

source code of linux/drivers/net/can/slcan/slcan-core.c