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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
5 *
6 * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk>
7 * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
8 * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, see http://www.gnu.org/licenses/gpl.html
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
33 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
34 * DAMAGE.
35 *
36 */
37
38#include <linux/module.h>
39#include <linux/moduleparam.h>
40
41#include <linux/uaccess.h>
42#include <linux/bitops.h>
43#include <linux/string.h>
44#include <linux/tty.h>
45#include <linux/errno.h>
46#include <linux/netdevice.h>
47#include <linux/skbuff.h>
48#include <linux/rtnetlink.h>
49#include <linux/if_arp.h>
50#include <linux/if_ether.h>
51#include <linux/sched.h>
52#include <linux/delay.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/skb.h>
58
59MODULE_ALIAS_LDISC(N_SLCAN);
60MODULE_DESCRIPTION("serial line CAN interface");
61MODULE_LICENSE("GPL");
62MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
63
64#define SLCAN_MAGIC 0x53CA
65
66static int maxdev = 10; /* MAX number of SLCAN channels;
67 This can be overridden with
68 insmod slcan.ko maxdev=nnn */
69module_param(maxdev, int, 0);
70MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
71
72/* maximum rx buffer len: extended CAN frame with timestamp */
73#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
74
75#define SLC_CMD_LEN 1
76#define SLC_SFF_ID_LEN 3
77#define SLC_EFF_ID_LEN 8
78
79struct slcan {
80 int magic;
81
82 /* Various fields. */
83 struct tty_struct *tty; /* ptr to TTY structure */
84 struct net_device *dev; /* easy for intr handling */
85 spinlock_t lock;
86 struct work_struct tx_work; /* Flushes transmit buffer */
87
88 /* These are pointers to the malloc()ed frame buffers. */
89 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
90 int rcount; /* received chars counter */
91 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
92 unsigned char *xhead; /* pointer to next XMIT byte */
93 int xleft; /* bytes left in XMIT queue */
94
95 unsigned long flags; /* Flag values/ mode etc */
96#define SLF_INUSE 0 /* Channel in use */
97#define SLF_ERROR 1 /* Parity, etc. error */
98};
99
100static struct net_device **slcan_devs;
101
102 /************************************************************************
103 * SLCAN ENCAPSULATION FORMAT *
104 ************************************************************************/
105
106/*
107 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
108 * frame format) a data length code (can_dlc) which can be from 0 to 8
109 * and up to <can_dlc> data bytes as payload.
110 * Additionally a CAN frame may become a remote transmission frame if the
111 * RTR-bit is set. This causes another ECU to send a CAN frame with the
112 * given can_id.
113 *
114 * The SLCAN ASCII representation of these different frame types is:
115 * <type> <id> <dlc> <data>*
116 *
117 * Extended frames (29 bit) are defined by capital characters in the type.
118 * RTR frames are defined as 'r' types - normal frames have 't' type:
119 * t => 11 bit data frame
120 * r => 11 bit RTR frame
121 * T => 29 bit data frame
122 * R => 29 bit RTR frame
123 *
124 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
125 * The <dlc> is a one byte ASCII number ('0' - '8')
126 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
127 *
128 * Examples:
129 *
130 * t1230 : can_id 0x123, can_dlc 0, no data
131 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
132 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
133 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
134 *
135 */
136
137 /************************************************************************
138 * STANDARD SLCAN DECAPSULATION *
139 ************************************************************************/
140
141/* Send one completely decapsulated can_frame to the network layer */
142static void slc_bump(struct slcan *sl)
143{
144 struct sk_buff *skb;
145 struct can_frame cf;
146 int i, tmp;
147 u32 tmpid;
148 char *cmd = sl->rbuff;
149
150 cf.can_id = 0;
151
152 switch (*cmd) {
153 case 'r':
154 cf.can_id = CAN_RTR_FLAG;
155 /* fallthrough */
156 case 't':
157 /* store dlc ASCII value and terminate SFF CAN ID string */
158 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
159 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
160 /* point to payload data behind the dlc */
161 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
162 break;
163 case 'R':
164 cf.can_id = CAN_RTR_FLAG;
165 /* fallthrough */
166 case 'T':
167 cf.can_id |= CAN_EFF_FLAG;
168 /* store dlc ASCII value and terminate EFF CAN ID string */
169 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
170 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
171 /* point to payload data behind the dlc */
172 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
173 break;
174 default:
175 return;
176 }
177
178 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
179 return;
180
181 cf.can_id |= tmpid;
182
183 /* get can_dlc from sanitized ASCII value */
184 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
185 cf.can_dlc -= '0';
186 else
187 return;
188
189 *(u64 *) (&cf.data) = 0; /* clear payload */
190
191 /* RTR frames may have a dlc > 0 but they never have any data bytes */
192 if (!(cf.can_id & CAN_RTR_FLAG)) {
193 for (i = 0; i < cf.can_dlc; i++) {
194 tmp = hex_to_bin(*cmd++);
195 if (tmp < 0)
196 return;
197 cf.data[i] = (tmp << 4);
198 tmp = hex_to_bin(*cmd++);
199 if (tmp < 0)
200 return;
201 cf.data[i] |= tmp;
202 }
203 }
204
205 skb = dev_alloc_skb(sizeof(struct can_frame) +
206 sizeof(struct can_skb_priv));
207 if (!skb)
208 return;
209
210 skb->dev = sl->dev;
211 skb->protocol = htons(ETH_P_CAN);
212 skb->pkt_type = PACKET_BROADCAST;
213 skb->ip_summed = CHECKSUM_UNNECESSARY;
214
215 can_skb_reserve(skb);
216 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
217 can_skb_prv(skb)->skbcnt = 0;
218
219 skb_put_data(skb, &cf, sizeof(struct can_frame));
220
221 sl->dev->stats.rx_packets++;
222 sl->dev->stats.rx_bytes += cf.can_dlc;
223 netif_rx_ni(skb);
224}
225
226/* parse tty input stream */
227static void slcan_unesc(struct slcan *sl, unsigned char s)
228{
229 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
230 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
231 (sl->rcount > 4)) {
232 slc_bump(sl);
233 }
234 sl->rcount = 0;
235 } else {
236 if (!test_bit(SLF_ERROR, &sl->flags)) {
237 if (sl->rcount < SLC_MTU) {
238 sl->rbuff[sl->rcount++] = s;
239 return;
240 } else {
241 sl->dev->stats.rx_over_errors++;
242 set_bit(SLF_ERROR, &sl->flags);
243 }
244 }
245 }
246}
247
248 /************************************************************************
249 * STANDARD SLCAN ENCAPSULATION *
250 ************************************************************************/
251
252/* Encapsulate one can_frame and stuff into a TTY queue. */
253static void slc_encaps(struct slcan *sl, struct can_frame *cf)
254{
255 int actual, i;
256 unsigned char *pos;
257 unsigned char *endpos;
258 canid_t id = cf->can_id;
259
260 pos = sl->xbuff;
261
262 if (cf->can_id & CAN_RTR_FLAG)
263 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
264 else
265 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
266
267 /* determine number of chars for the CAN-identifier */
268 if (cf->can_id & CAN_EFF_FLAG) {
269 id &= CAN_EFF_MASK;
270 endpos = pos + SLC_EFF_ID_LEN;
271 } else {
272 *pos |= 0x20; /* convert R/T to lower case for SFF */
273 id &= CAN_SFF_MASK;
274 endpos = pos + SLC_SFF_ID_LEN;
275 }
276
277 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
278 pos++;
279 while (endpos >= pos) {
280 *endpos-- = hex_asc_upper[id & 0xf];
281 id >>= 4;
282 }
283
284 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
285
286 *pos++ = cf->can_dlc + '0';
287
288 /* RTR frames may have a dlc > 0 but they never have any data bytes */
289 if (!(cf->can_id & CAN_RTR_FLAG)) {
290 for (i = 0; i < cf->can_dlc; i++)
291 pos = hex_byte_pack_upper(pos, cf->data[i]);
292 }
293
294 *pos++ = '\r';
295
296 /* Order of next two lines is *very* important.
297 * When we are sending a little amount of data,
298 * the transfer may be completed inside the ops->write()
299 * routine, because it's running with interrupts enabled.
300 * In this case we *never* got WRITE_WAKEUP event,
301 * if we did not request it before write operation.
302 * 14 Oct 1994 Dmitry Gorodchanin.
303 */
304 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
305 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
306 sl->xleft = (pos - sl->xbuff) - actual;
307 sl->xhead = sl->xbuff + actual;
308 sl->dev->stats.tx_bytes += cf->can_dlc;
309}
310
311/* Write out any remaining transmit buffer. Scheduled when tty is writable */
312static void slcan_transmit(struct work_struct *work)
313{
314 struct slcan *sl = container_of(work, struct slcan, tx_work);
315 int actual;
316
317 spin_lock_bh(&sl->lock);
318 /* First make sure we're connected. */
319 if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
320 spin_unlock_bh(&sl->lock);
321 return;
322 }
323
324 if (sl->xleft <= 0) {
325 /* Now serial buffer is almost free & we can start
326 * transmission of another packet */
327 sl->dev->stats.tx_packets++;
328 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
329 spin_unlock_bh(&sl->lock);
330 netif_wake_queue(sl->dev);
331 return;
332 }
333
334 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
335 sl->xleft -= actual;
336 sl->xhead += actual;
337 spin_unlock_bh(&sl->lock);
338}
339
340/*
341 * Called by the driver when there's room for more data.
342 * Schedule the transmit.
343 */
344static void slcan_write_wakeup(struct tty_struct *tty)
345{
346 struct slcan *sl = tty->disc_data;
347
348 schedule_work(&sl->tx_work);
349}
350
351/* Send a can_frame to a TTY queue. */
352static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
353{
354 struct slcan *sl = netdev_priv(dev);
355
356 if (skb->len != CAN_MTU)
357 goto out;
358
359 spin_lock(&sl->lock);
360 if (!netif_running(dev)) {
361 spin_unlock(&sl->lock);
362 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
363 goto out;
364 }
365 if (sl->tty == NULL) {
366 spin_unlock(&sl->lock);
367 goto out;
368 }
369
370 netif_stop_queue(sl->dev);
371 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
372 spin_unlock(&sl->lock);
373
374out:
375 kfree_skb(skb);
376 return NETDEV_TX_OK;
377}
378
379
380/******************************************
381 * Routines looking at netdevice side.
382 ******************************************/
383
384/* Netdevice UP -> DOWN routine */
385static int slc_close(struct net_device *dev)
386{
387 struct slcan *sl = netdev_priv(dev);
388
389 spin_lock_bh(&sl->lock);
390 if (sl->tty) {
391 /* TTY discipline is running. */
392 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
393 }
394 netif_stop_queue(dev);
395 sl->rcount = 0;
396 sl->xleft = 0;
397 spin_unlock_bh(&sl->lock);
398
399 return 0;
400}
401
402/* Netdevice DOWN -> UP routine */
403static int slc_open(struct net_device *dev)
404{
405 struct slcan *sl = netdev_priv(dev);
406
407 if (sl->tty == NULL)
408 return -ENODEV;
409
410 sl->flags &= (1 << SLF_INUSE);
411 netif_start_queue(dev);
412 return 0;
413}
414
415/* Hook the destructor so we can free slcan devs at the right point in time */
416static void slc_free_netdev(struct net_device *dev)
417{
418 int i = dev->base_addr;
419
420 slcan_devs[i] = NULL;
421}
422
423static int slcan_change_mtu(struct net_device *dev, int new_mtu)
424{
425 return -EINVAL;
426}
427
428static const struct net_device_ops slc_netdev_ops = {
429 .ndo_open = slc_open,
430 .ndo_stop = slc_close,
431 .ndo_start_xmit = slc_xmit,
432 .ndo_change_mtu = slcan_change_mtu,
433};
434
435static void slc_setup(struct net_device *dev)
436{
437 dev->netdev_ops = &slc_netdev_ops;
438 dev->needs_free_netdev = true;
439 dev->priv_destructor = slc_free_netdev;
440
441 dev->hard_header_len = 0;
442 dev->addr_len = 0;
443 dev->tx_queue_len = 10;
444
445 dev->mtu = CAN_MTU;
446 dev->type = ARPHRD_CAN;
447
448 /* New-style flags. */
449 dev->flags = IFF_NOARP;
450 dev->features = NETIF_F_HW_CSUM;
451}
452
453/******************************************
454 Routines looking at TTY side.
455 ******************************************/
456
457/*
458 * Handle the 'receiver data ready' interrupt.
459 * This function is called by the 'tty_io' module in the kernel when
460 * a block of SLCAN data has been received, which can now be decapsulated
461 * and sent on to some IP layer for further processing. This will not
462 * be re-entered while running but other ldisc functions may be called
463 * in parallel
464 */
465
466static void slcan_receive_buf(struct tty_struct *tty,
467 const unsigned char *cp, char *fp, int count)
468{
469 struct slcan *sl = (struct slcan *) tty->disc_data;
470
471 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
472 return;
473
474 /* Read the characters out of the buffer */
475 while (count--) {
476 if (fp && *fp++) {
477 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
478 sl->dev->stats.rx_errors++;
479 cp++;
480 continue;
481 }
482 slcan_unesc(sl, *cp++);
483 }
484}
485
486/************************************
487 * slcan_open helper routines.
488 ************************************/
489
490/* Collect hanged up channels */
491static void slc_sync(void)
492{
493 int i;
494 struct net_device *dev;
495 struct slcan *sl;
496
497 for (i = 0; i < maxdev; i++) {
498 dev = slcan_devs[i];
499 if (dev == NULL)
500 break;
501
502 sl = netdev_priv(dev);
503 if (sl->tty)
504 continue;
505 if (dev->flags & IFF_UP)
506 dev_close(dev);
507 }
508}
509
510/* Find a free SLCAN channel, and link in this `tty' line. */
511static struct slcan *slc_alloc(void)
512{
513 int i;
514 char name[IFNAMSIZ];
515 struct net_device *dev = NULL;
516 struct slcan *sl;
517
518 for (i = 0; i < maxdev; i++) {
519 dev = slcan_devs[i];
520 if (dev == NULL)
521 break;
522
523 }
524
525 /* Sorry, too many, all slots in use */
526 if (i >= maxdev)
527 return NULL;
528
529 sprintf(name, "slcan%d", i);
530 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, slc_setup);
531 if (!dev)
532 return NULL;
533
534 dev->base_addr = i;
535 sl = netdev_priv(dev);
536
537 /* Initialize channel control data */
538 sl->magic = SLCAN_MAGIC;
539 sl->dev = dev;
540 spin_lock_init(&sl->lock);
541 INIT_WORK(&sl->tx_work, slcan_transmit);
542 slcan_devs[i] = dev;
543
544 return sl;
545}
546
547/*
548 * Open the high-level part of the SLCAN channel.
549 * This function is called by the TTY module when the
550 * SLCAN line discipline is called for. Because we are
551 * sure the tty line exists, we only have to link it to
552 * a free SLCAN channel...
553 *
554 * Called in process context serialized from other ldisc calls.
555 */
556
557static int slcan_open(struct tty_struct *tty)
558{
559 struct slcan *sl;
560 int err;
561
562 if (!capable(CAP_NET_ADMIN))
563 return -EPERM;
564
565 if (tty->ops->write == NULL)
566 return -EOPNOTSUPP;
567
568 /* RTnetlink lock is misused here to serialize concurrent
569 opens of slcan channels. There are better ways, but it is
570 the simplest one.
571 */
572 rtnl_lock();
573
574 /* Collect hanged up channels. */
575 slc_sync();
576
577 sl = tty->disc_data;
578
579 err = -EEXIST;
580 /* First make sure we're not already connected. */
581 if (sl && sl->magic == SLCAN_MAGIC)
582 goto err_exit;
583
584 /* OK. Find a free SLCAN channel to use. */
585 err = -ENFILE;
586 sl = slc_alloc();
587 if (sl == NULL)
588 goto err_exit;
589
590 sl->tty = tty;
591 tty->disc_data = sl;
592
593 if (!test_bit(SLF_INUSE, &sl->flags)) {
594 /* Perform the low-level SLCAN initialization. */
595 sl->rcount = 0;
596 sl->xleft = 0;
597
598 set_bit(SLF_INUSE, &sl->flags);
599
600 err = register_netdevice(sl->dev);
601 if (err)
602 goto err_free_chan;
603 }
604
605 /* Done. We have linked the TTY line to a channel. */
606 rtnl_unlock();
607 tty->receive_room = 65536; /* We don't flow control */
608
609 /* TTY layer expects 0 on success */
610 return 0;
611
612err_free_chan:
613 sl->tty = NULL;
614 tty->disc_data = NULL;
615 clear_bit(SLF_INUSE, &sl->flags);
616
617err_exit:
618 rtnl_unlock();
619
620 /* Count references from TTY module */
621 return err;
622}
623
624/*
625 * Close down a SLCAN channel.
626 * This means flushing out any pending queues, and then returning. This
627 * call is serialized against other ldisc functions.
628 *
629 * We also use this method for a hangup event.
630 */
631
632static void slcan_close(struct tty_struct *tty)
633{
634 struct slcan *sl = (struct slcan *) tty->disc_data;
635
636 /* First make sure we're connected. */
637 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
638 return;
639
640 spin_lock_bh(&sl->lock);
641 tty->disc_data = NULL;
642 sl->tty = NULL;
643 spin_unlock_bh(&sl->lock);
644
645 flush_work(&sl->tx_work);
646
647 /* Flush network side */
648 unregister_netdev(sl->dev);
649 /* This will complete via sl_free_netdev */
650}
651
652static int slcan_hangup(struct tty_struct *tty)
653{
654 slcan_close(tty);
655 return 0;
656}
657
658/* Perform I/O control on an active SLCAN channel. */
659static int slcan_ioctl(struct tty_struct *tty, struct file *file,
660 unsigned int cmd, unsigned long arg)
661{
662 struct slcan *sl = (struct slcan *) tty->disc_data;
663 unsigned int tmp;
664
665 /* First make sure we're connected. */
666 if (!sl || sl->magic != SLCAN_MAGIC)
667 return -EINVAL;
668
669 switch (cmd) {
670 case SIOCGIFNAME:
671 tmp = strlen(sl->dev->name) + 1;
672 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
673 return -EFAULT;
674 return 0;
675
676 case SIOCSIFHWADDR:
677 return -EINVAL;
678
679 default:
680 return tty_mode_ioctl(tty, file, cmd, arg);
681 }
682}
683
684static struct tty_ldisc_ops slc_ldisc = {
685 .owner = THIS_MODULE,
686 .magic = TTY_LDISC_MAGIC,
687 .name = "slcan",
688 .open = slcan_open,
689 .close = slcan_close,
690 .hangup = slcan_hangup,
691 .ioctl = slcan_ioctl,
692 .receive_buf = slcan_receive_buf,
693 .write_wakeup = slcan_write_wakeup,
694};
695
696static int __init slcan_init(void)
697{
698 int status;
699
700 if (maxdev < 4)
701 maxdev = 4; /* Sanity */
702
703 pr_info("slcan: serial line CAN interface driver\n");
704 pr_info("slcan: %d dynamic interface channels.\n", maxdev);
705
706 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
707 if (!slcan_devs)
708 return -ENOMEM;
709
710 /* Fill in our line protocol discipline, and register it */
711 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
712 if (status) {
713 printk(KERN_ERR "slcan: can't register line discipline\n");
714 kfree(slcan_devs);
715 }
716 return status;
717}
718
719static void __exit slcan_exit(void)
720{
721 int i;
722 struct net_device *dev;
723 struct slcan *sl;
724 unsigned long timeout = jiffies + HZ;
725 int busy = 0;
726
727 if (slcan_devs == NULL)
728 return;
729
730 /* First of all: check for active disciplines and hangup them.
731 */
732 do {
733 if (busy)
734 msleep_interruptible(100);
735
736 busy = 0;
737 for (i = 0; i < maxdev; i++) {
738 dev = slcan_devs[i];
739 if (!dev)
740 continue;
741 sl = netdev_priv(dev);
742 spin_lock_bh(&sl->lock);
743 if (sl->tty) {
744 busy++;
745 tty_hangup(sl->tty);
746 }
747 spin_unlock_bh(&sl->lock);
748 }
749 } while (busy && time_before(jiffies, timeout));
750
751 /* FIXME: hangup is async so we should wait when doing this second
752 phase */
753
754 for (i = 0; i < maxdev; i++) {
755 dev = slcan_devs[i];
756 if (!dev)
757 continue;
758 slcan_devs[i] = NULL;
759
760 sl = netdev_priv(dev);
761 if (sl->tty) {
762 printk(KERN_ERR "%s: tty discipline still running\n",
763 dev->name);
764 }
765
766 unregister_netdev(dev);
767 }
768
769 kfree(slcan_devs);
770 slcan_devs = NULL;
771
772 i = tty_unregister_ldisc(N_SLCAN);
773 if (i)
774 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
775}
776
777module_init(slcan_init);
778module_exit(slcan_exit);
1/*
2 * slcan.c - serial line CAN interface driver (using tty line discipline)
3 *
4 * This file is derived from linux/drivers/net/slip.c
5 *
6 * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk>
7 * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
8 * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net>
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it
23 * at http://www.gnu.org/licenses/gpl.html
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
36 * DAMAGE.
37 *
38 * Send feedback to <socketcan-users@lists.berlios.de>
39 *
40 */
41
42#include <linux/module.h>
43#include <linux/moduleparam.h>
44
45#include <asm/system.h>
46#include <linux/uaccess.h>
47#include <linux/bitops.h>
48#include <linux/string.h>
49#include <linux/tty.h>
50#include <linux/errno.h>
51#include <linux/netdevice.h>
52#include <linux/skbuff.h>
53#include <linux/rtnetlink.h>
54#include <linux/if_arp.h>
55#include <linux/if_ether.h>
56#include <linux/sched.h>
57#include <linux/delay.h>
58#include <linux/init.h>
59#include <linux/kernel.h>
60#include <linux/can.h>
61
62static __initdata const char banner[] =
63 KERN_INFO "slcan: serial line CAN interface driver\n";
64
65MODULE_ALIAS_LDISC(N_SLCAN);
66MODULE_DESCRIPTION("serial line CAN interface");
67MODULE_LICENSE("GPL");
68MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
69
70#define SLCAN_MAGIC 0x53CA
71
72static int maxdev = 10; /* MAX number of SLCAN channels;
73 This can be overridden with
74 insmod slcan.ko maxdev=nnn */
75module_param(maxdev, int, 0);
76MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
77
78/* maximum rx buffer len: extended CAN frame with timestamp */
79#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
80
81struct slcan {
82 int magic;
83
84 /* Various fields. */
85 struct tty_struct *tty; /* ptr to TTY structure */
86 struct net_device *dev; /* easy for intr handling */
87 spinlock_t lock;
88
89 /* These are pointers to the malloc()ed frame buffers. */
90 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
91 int rcount; /* received chars counter */
92 unsigned char xbuff[SLC_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_INUSE 0 /* Channel in use */
98#define SLF_ERROR 1 /* Parity, etc. error */
99};
100
101static struct net_device **slcan_devs;
102
103 /************************************************************************
104 * SLCAN ENCAPSULATION FORMAT *
105 ************************************************************************/
106
107/*
108 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
109 * frame format) a data length code (can_dlc) which can be from 0 to 8
110 * and up to <can_dlc> data bytes as payload.
111 * Additionally a CAN frame may become a remote transmission frame if the
112 * RTR-bit is set. This causes another ECU to send a CAN frame with the
113 * given can_id.
114 *
115 * The SLCAN ASCII representation of these different frame types is:
116 * <type> <id> <dlc> <data>*
117 *
118 * Extended frames (29 bit) are defined by capital characters in the type.
119 * RTR frames are defined as 'r' types - normal frames have 't' type:
120 * t => 11 bit data frame
121 * r => 11 bit RTR frame
122 * T => 29 bit data frame
123 * R => 29 bit RTR frame
124 *
125 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
126 * The <dlc> is a one byte ASCII number ('0' - '8')
127 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
128 *
129 * Examples:
130 *
131 * t1230 : can_id 0x123, can_dlc 0, no data
132 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
133 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
134 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
135 *
136 */
137
138 /************************************************************************
139 * STANDARD SLCAN DECAPSULATION *
140 ************************************************************************/
141
142/* Send one completely decapsulated can_frame to the network layer */
143static void slc_bump(struct slcan *sl)
144{
145 struct sk_buff *skb;
146 struct can_frame cf;
147 int i, dlc_pos, tmp;
148 unsigned long ultmp;
149 char cmd = sl->rbuff[0];
150
151 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
152 return;
153
154 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
155 dlc_pos = 4; /* dlc position tiiid */
156 else
157 dlc_pos = 9; /* dlc position Tiiiiiiiid */
158
159 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
160 return;
161
162 cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
163
164 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
165
166 if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
167 return;
168
169 cf.can_id = ultmp;
170
171 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
172 cf.can_id |= CAN_EFF_FLAG;
173
174 if ((cmd | 0x20) == 'r') /* RTR frame */
175 cf.can_id |= CAN_RTR_FLAG;
176
177 *(u64 *) (&cf.data) = 0; /* clear payload */
178
179 for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
180 tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
181 if (tmp < 0)
182 return;
183 cf.data[i] = (tmp << 4);
184 tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
185 if (tmp < 0)
186 return;
187 cf.data[i] |= tmp;
188 }
189
190 skb = dev_alloc_skb(sizeof(struct can_frame));
191 if (!skb)
192 return;
193
194 skb->dev = sl->dev;
195 skb->protocol = htons(ETH_P_CAN);
196 skb->pkt_type = PACKET_BROADCAST;
197 skb->ip_summed = CHECKSUM_UNNECESSARY;
198 memcpy(skb_put(skb, sizeof(struct can_frame)),
199 &cf, sizeof(struct can_frame));
200 netif_rx_ni(skb);
201
202 sl->dev->stats.rx_packets++;
203 sl->dev->stats.rx_bytes += cf.can_dlc;
204}
205
206/* parse tty input stream */
207static void slcan_unesc(struct slcan *sl, unsigned char s)
208{
209
210 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
211 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
212 (sl->rcount > 4)) {
213 slc_bump(sl);
214 }
215 sl->rcount = 0;
216 } else {
217 if (!test_bit(SLF_ERROR, &sl->flags)) {
218 if (sl->rcount < SLC_MTU) {
219 sl->rbuff[sl->rcount++] = s;
220 return;
221 } else {
222 sl->dev->stats.rx_over_errors++;
223 set_bit(SLF_ERROR, &sl->flags);
224 }
225 }
226 }
227}
228
229 /************************************************************************
230 * STANDARD SLCAN ENCAPSULATION *
231 ************************************************************************/
232
233/* Encapsulate one can_frame and stuff into a TTY queue. */
234static void slc_encaps(struct slcan *sl, struct can_frame *cf)
235{
236 int actual, idx, i;
237 char cmd;
238
239 if (cf->can_id & CAN_RTR_FLAG)
240 cmd = 'R'; /* becomes 'r' in standard frame format */
241 else
242 cmd = 'T'; /* becomes 't' in standard frame format */
243
244 if (cf->can_id & CAN_EFF_FLAG)
245 sprintf(sl->xbuff, "%c%08X%d", cmd,
246 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
247 else
248 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
249 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
250
251 idx = strlen(sl->xbuff);
252
253 for (i = 0; i < cf->can_dlc; i++)
254 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
255
256 strcat(sl->xbuff, "\r"); /* add terminating character */
257
258 /* Order of next two lines is *very* important.
259 * When we are sending a little amount of data,
260 * the transfer may be completed inside the ops->write()
261 * routine, because it's running with interrupts enabled.
262 * In this case we *never* got WRITE_WAKEUP event,
263 * if we did not request it before write operation.
264 * 14 Oct 1994 Dmitry Gorodchanin.
265 */
266 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
267 actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
268 sl->xleft = strlen(sl->xbuff) - actual;
269 sl->xhead = sl->xbuff + actual;
270 sl->dev->stats.tx_bytes += cf->can_dlc;
271}
272
273/*
274 * Called by the driver when there's room for more data. If we have
275 * more packets to send, we send them here.
276 */
277static void slcan_write_wakeup(struct tty_struct *tty)
278{
279 int actual;
280 struct slcan *sl = (struct slcan *) tty->disc_data;
281
282 /* First make sure we're connected. */
283 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
284 return;
285
286 if (sl->xleft <= 0) {
287 /* Now serial buffer is almost free & we can start
288 * transmission of another packet */
289 sl->dev->stats.tx_packets++;
290 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
291 netif_wake_queue(sl->dev);
292 return;
293 }
294
295 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
296 sl->xleft -= actual;
297 sl->xhead += actual;
298}
299
300/* Send a can_frame to a TTY queue. */
301static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
302{
303 struct slcan *sl = netdev_priv(dev);
304
305 if (skb->len != sizeof(struct can_frame))
306 goto out;
307
308 spin_lock(&sl->lock);
309 if (!netif_running(dev)) {
310 spin_unlock(&sl->lock);
311 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
312 goto out;
313 }
314 if (sl->tty == NULL) {
315 spin_unlock(&sl->lock);
316 goto out;
317 }
318
319 netif_stop_queue(sl->dev);
320 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
321 spin_unlock(&sl->lock);
322
323out:
324 kfree_skb(skb);
325 return NETDEV_TX_OK;
326}
327
328
329/******************************************
330 * Routines looking at netdevice side.
331 ******************************************/
332
333/* Netdevice UP -> DOWN routine */
334static int slc_close(struct net_device *dev)
335{
336 struct slcan *sl = netdev_priv(dev);
337
338 spin_lock_bh(&sl->lock);
339 if (sl->tty) {
340 /* TTY discipline is running. */
341 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
342 }
343 netif_stop_queue(dev);
344 sl->rcount = 0;
345 sl->xleft = 0;
346 spin_unlock_bh(&sl->lock);
347
348 return 0;
349}
350
351/* Netdevice DOWN -> UP routine */
352static int slc_open(struct net_device *dev)
353{
354 struct slcan *sl = netdev_priv(dev);
355
356 if (sl->tty == NULL)
357 return -ENODEV;
358
359 sl->flags &= (1 << SLF_INUSE);
360 netif_start_queue(dev);
361 return 0;
362}
363
364/* Hook the destructor so we can free slcan devs at the right point in time */
365static void slc_free_netdev(struct net_device *dev)
366{
367 int i = dev->base_addr;
368 free_netdev(dev);
369 slcan_devs[i] = NULL;
370}
371
372static const struct net_device_ops slc_netdev_ops = {
373 .ndo_open = slc_open,
374 .ndo_stop = slc_close,
375 .ndo_start_xmit = slc_xmit,
376};
377
378static void slc_setup(struct net_device *dev)
379{
380 dev->netdev_ops = &slc_netdev_ops;
381 dev->destructor = slc_free_netdev;
382
383 dev->hard_header_len = 0;
384 dev->addr_len = 0;
385 dev->tx_queue_len = 10;
386
387 dev->mtu = sizeof(struct can_frame);
388 dev->type = ARPHRD_CAN;
389
390 /* New-style flags. */
391 dev->flags = IFF_NOARP;
392 dev->features = NETIF_F_NO_CSUM;
393}
394
395/******************************************
396 Routines looking at TTY side.
397 ******************************************/
398
399/*
400 * Handle the 'receiver data ready' interrupt.
401 * This function is called by the 'tty_io' module in the kernel when
402 * a block of SLCAN data has been received, which can now be decapsulated
403 * and sent on to some IP layer for further processing. This will not
404 * be re-entered while running but other ldisc functions may be called
405 * in parallel
406 */
407
408static void slcan_receive_buf(struct tty_struct *tty,
409 const unsigned char *cp, char *fp, int count)
410{
411 struct slcan *sl = (struct slcan *) tty->disc_data;
412
413 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
414 return;
415
416 /* Read the characters out of the buffer */
417 while (count--) {
418 if (fp && *fp++) {
419 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
420 sl->dev->stats.rx_errors++;
421 cp++;
422 continue;
423 }
424 slcan_unesc(sl, *cp++);
425 }
426}
427
428/************************************
429 * slcan_open helper routines.
430 ************************************/
431
432/* Collect hanged up channels */
433static void slc_sync(void)
434{
435 int i;
436 struct net_device *dev;
437 struct slcan *sl;
438
439 for (i = 0; i < maxdev; i++) {
440 dev = slcan_devs[i];
441 if (dev == NULL)
442 break;
443
444 sl = netdev_priv(dev);
445 if (sl->tty)
446 continue;
447 if (dev->flags & IFF_UP)
448 dev_close(dev);
449 }
450}
451
452/* Find a free SLCAN channel, and link in this `tty' line. */
453static struct slcan *slc_alloc(dev_t line)
454{
455 int i;
456 char name[IFNAMSIZ];
457 struct net_device *dev = NULL;
458 struct slcan *sl;
459
460 for (i = 0; i < maxdev; i++) {
461 dev = slcan_devs[i];
462 if (dev == NULL)
463 break;
464
465 }
466
467 /* Sorry, too many, all slots in use */
468 if (i >= maxdev)
469 return NULL;
470
471 sprintf(name, "slcan%d", i);
472 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
473 if (!dev)
474 return NULL;
475
476 dev->base_addr = i;
477 sl = netdev_priv(dev);
478
479 /* Initialize channel control data */
480 sl->magic = SLCAN_MAGIC;
481 sl->dev = dev;
482 spin_lock_init(&sl->lock);
483 slcan_devs[i] = dev;
484
485 return sl;
486}
487
488/*
489 * Open the high-level part of the SLCAN channel.
490 * This function is called by the TTY module when the
491 * SLCAN line discipline is called for. Because we are
492 * sure the tty line exists, we only have to link it to
493 * a free SLCAN channel...
494 *
495 * Called in process context serialized from other ldisc calls.
496 */
497
498static int slcan_open(struct tty_struct *tty)
499{
500 struct slcan *sl;
501 int err;
502
503 if (!capable(CAP_NET_ADMIN))
504 return -EPERM;
505
506 if (tty->ops->write == NULL)
507 return -EOPNOTSUPP;
508
509 /* RTnetlink lock is misused here to serialize concurrent
510 opens of slcan channels. There are better ways, but it is
511 the simplest one.
512 */
513 rtnl_lock();
514
515 /* Collect hanged up channels. */
516 slc_sync();
517
518 sl = tty->disc_data;
519
520 err = -EEXIST;
521 /* First make sure we're not already connected. */
522 if (sl && sl->magic == SLCAN_MAGIC)
523 goto err_exit;
524
525 /* OK. Find a free SLCAN channel to use. */
526 err = -ENFILE;
527 sl = slc_alloc(tty_devnum(tty));
528 if (sl == NULL)
529 goto err_exit;
530
531 sl->tty = tty;
532 tty->disc_data = sl;
533
534 if (!test_bit(SLF_INUSE, &sl->flags)) {
535 /* Perform the low-level SLCAN initialization. */
536 sl->rcount = 0;
537 sl->xleft = 0;
538
539 set_bit(SLF_INUSE, &sl->flags);
540
541 err = register_netdevice(sl->dev);
542 if (err)
543 goto err_free_chan;
544 }
545
546 /* Done. We have linked the TTY line to a channel. */
547 rtnl_unlock();
548 tty->receive_room = 65536; /* We don't flow control */
549
550 /* TTY layer expects 0 on success */
551 return 0;
552
553err_free_chan:
554 sl->tty = NULL;
555 tty->disc_data = NULL;
556 clear_bit(SLF_INUSE, &sl->flags);
557
558err_exit:
559 rtnl_unlock();
560
561 /* Count references from TTY module */
562 return err;
563}
564
565/*
566 * Close down a SLCAN channel.
567 * This means flushing out any pending queues, and then returning. This
568 * call is serialized against other ldisc functions.
569 *
570 * We also use this method for a hangup event.
571 */
572
573static void slcan_close(struct tty_struct *tty)
574{
575 struct slcan *sl = (struct slcan *) tty->disc_data;
576
577 /* First make sure we're connected. */
578 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
579 return;
580
581 tty->disc_data = NULL;
582 sl->tty = NULL;
583
584 /* Flush network side */
585 unregister_netdev(sl->dev);
586 /* This will complete via sl_free_netdev */
587}
588
589static int slcan_hangup(struct tty_struct *tty)
590{
591 slcan_close(tty);
592 return 0;
593}
594
595/* Perform I/O control on an active SLCAN channel. */
596static int slcan_ioctl(struct tty_struct *tty, struct file *file,
597 unsigned int cmd, unsigned long arg)
598{
599 struct slcan *sl = (struct slcan *) tty->disc_data;
600 unsigned int tmp;
601
602 /* First make sure we're connected. */
603 if (!sl || sl->magic != SLCAN_MAGIC)
604 return -EINVAL;
605
606 switch (cmd) {
607 case SIOCGIFNAME:
608 tmp = strlen(sl->dev->name) + 1;
609 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
610 return -EFAULT;
611 return 0;
612
613 case SIOCSIFHWADDR:
614 return -EINVAL;
615
616 default:
617 return tty_mode_ioctl(tty, file, cmd, arg);
618 }
619}
620
621static struct tty_ldisc_ops slc_ldisc = {
622 .owner = THIS_MODULE,
623 .magic = TTY_LDISC_MAGIC,
624 .name = "slcan",
625 .open = slcan_open,
626 .close = slcan_close,
627 .hangup = slcan_hangup,
628 .ioctl = slcan_ioctl,
629 .receive_buf = slcan_receive_buf,
630 .write_wakeup = slcan_write_wakeup,
631};
632
633static int __init slcan_init(void)
634{
635 int status;
636
637 if (maxdev < 4)
638 maxdev = 4; /* Sanity */
639
640 printk(banner);
641 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
642
643 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
644 if (!slcan_devs) {
645 printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
646 return -ENOMEM;
647 }
648
649 /* Fill in our line protocol discipline, and register it */
650 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
651 if (status) {
652 printk(KERN_ERR "slcan: can't register line discipline\n");
653 kfree(slcan_devs);
654 }
655 return status;
656}
657
658static void __exit slcan_exit(void)
659{
660 int i;
661 struct net_device *dev;
662 struct slcan *sl;
663 unsigned long timeout = jiffies + HZ;
664 int busy = 0;
665
666 if (slcan_devs == NULL)
667 return;
668
669 /* First of all: check for active disciplines and hangup them.
670 */
671 do {
672 if (busy)
673 msleep_interruptible(100);
674
675 busy = 0;
676 for (i = 0; i < maxdev; i++) {
677 dev = slcan_devs[i];
678 if (!dev)
679 continue;
680 sl = netdev_priv(dev);
681 spin_lock_bh(&sl->lock);
682 if (sl->tty) {
683 busy++;
684 tty_hangup(sl->tty);
685 }
686 spin_unlock_bh(&sl->lock);
687 }
688 } while (busy && time_before(jiffies, timeout));
689
690 /* FIXME: hangup is async so we should wait when doing this second
691 phase */
692
693 for (i = 0; i < maxdev; i++) {
694 dev = slcan_devs[i];
695 if (!dev)
696 continue;
697 slcan_devs[i] = NULL;
698
699 sl = netdev_priv(dev);
700 if (sl->tty) {
701 printk(KERN_ERR "%s: tty discipline still running\n",
702 dev->name);
703 /* Intentionally leak the control block. */
704 dev->destructor = NULL;
705 }
706
707 unregister_netdev(dev);
708 }
709
710 kfree(slcan_devs);
711 slcan_devs = NULL;
712
713 i = tty_unregister_ldisc(N_SLCAN);
714 if (i)
715 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
716}
717
718module_init(slcan_init);
719module_exit(slcan_exit);