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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#include <linux/can/can-ml.h>
59
60MODULE_ALIAS_LDISC(N_SLCAN);
61MODULE_DESCRIPTION("serial line CAN interface");
62MODULE_LICENSE("GPL");
63MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
64
65#define SLCAN_MAGIC 0x53CA
66
67static int maxdev = 10; /* MAX number of SLCAN channels;
68 This can be overridden with
69 insmod slcan.ko maxdev=nnn */
70module_param(maxdev, int, 0);
71MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
72
73/* maximum rx buffer len: extended CAN frame with timestamp */
74#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
75
76#define SLC_CMD_LEN 1
77#define SLC_SFF_ID_LEN 3
78#define SLC_EFF_ID_LEN 8
79
80struct slcan {
81 int magic;
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[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, tmp;
148 u32 tmpid;
149 char *cmd = sl->rbuff;
150
151 memset(&cf, 0, sizeof(cf));
152
153 switch (*cmd) {
154 case 'r':
155 cf.can_id = CAN_RTR_FLAG;
156 fallthrough;
157 case 't':
158 /* store dlc ASCII value and terminate SFF CAN ID string */
159 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
160 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
161 /* point to payload data behind the dlc */
162 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
163 break;
164 case 'R':
165 cf.can_id = CAN_RTR_FLAG;
166 fallthrough;
167 case 'T':
168 cf.can_id |= CAN_EFF_FLAG;
169 /* store dlc ASCII value and terminate EFF CAN ID string */
170 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
171 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
172 /* point to payload data behind the dlc */
173 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
174 break;
175 default:
176 return;
177 }
178
179 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
180 return;
181
182 cf.can_id |= tmpid;
183
184 /* get can_dlc from sanitized ASCII value */
185 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
186 cf.can_dlc -= '0';
187 else
188 return;
189
190 /* RTR frames may have a dlc > 0 but they never have any data bytes */
191 if (!(cf.can_id & CAN_RTR_FLAG)) {
192 for (i = 0; i < cf.can_dlc; i++) {
193 tmp = hex_to_bin(*cmd++);
194 if (tmp < 0)
195 return;
196 cf.data[i] = (tmp << 4);
197 tmp = hex_to_bin(*cmd++);
198 if (tmp < 0)
199 return;
200 cf.data[i] |= tmp;
201 }
202 }
203
204 skb = dev_alloc_skb(sizeof(struct can_frame) +
205 sizeof(struct can_skb_priv));
206 if (!skb)
207 return;
208
209 skb->dev = sl->dev;
210 skb->protocol = htons(ETH_P_CAN);
211 skb->pkt_type = PACKET_BROADCAST;
212 skb->ip_summed = CHECKSUM_UNNECESSARY;
213
214 can_skb_reserve(skb);
215 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
216 can_skb_prv(skb)->skbcnt = 0;
217
218 skb_put_data(skb, &cf, sizeof(struct can_frame));
219
220 sl->dev->stats.rx_packets++;
221 sl->dev->stats.rx_bytes += cf.can_dlc;
222 netif_rx_ni(skb);
223}
224
225/* parse tty input stream */
226static void slcan_unesc(struct slcan *sl, unsigned char s)
227{
228 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
229 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
230 (sl->rcount > 4)) {
231 slc_bump(sl);
232 }
233 sl->rcount = 0;
234 } else {
235 if (!test_bit(SLF_ERROR, &sl->flags)) {
236 if (sl->rcount < SLC_MTU) {
237 sl->rbuff[sl->rcount++] = s;
238 return;
239 } else {
240 sl->dev->stats.rx_over_errors++;
241 set_bit(SLF_ERROR, &sl->flags);
242 }
243 }
244 }
245}
246
247 /************************************************************************
248 * STANDARD SLCAN ENCAPSULATION *
249 ************************************************************************/
250
251/* Encapsulate one can_frame and stuff into a TTY queue. */
252static void slc_encaps(struct slcan *sl, struct can_frame *cf)
253{
254 int actual, i;
255 unsigned char *pos;
256 unsigned char *endpos;
257 canid_t id = cf->can_id;
258
259 pos = sl->xbuff;
260
261 if (cf->can_id & CAN_RTR_FLAG)
262 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
263 else
264 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
265
266 /* determine number of chars for the CAN-identifier */
267 if (cf->can_id & CAN_EFF_FLAG) {
268 id &= CAN_EFF_MASK;
269 endpos = pos + SLC_EFF_ID_LEN;
270 } else {
271 *pos |= 0x20; /* convert R/T to lower case for SFF */
272 id &= CAN_SFF_MASK;
273 endpos = pos + SLC_SFF_ID_LEN;
274 }
275
276 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
277 pos++;
278 while (endpos >= pos) {
279 *endpos-- = hex_asc_upper[id & 0xf];
280 id >>= 4;
281 }
282
283 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
284
285 *pos++ = cf->can_dlc + '0';
286
287 /* RTR frames may have a dlc > 0 but they never have any data bytes */
288 if (!(cf->can_id & CAN_RTR_FLAG)) {
289 for (i = 0; i < cf->can_dlc; i++)
290 pos = hex_byte_pack_upper(pos, cf->data[i]);
291 }
292
293 *pos++ = '\r';
294
295 /* Order of next two lines is *very* important.
296 * When we are sending a little amount of data,
297 * the transfer may be completed inside the ops->write()
298 * routine, because it's running with interrupts enabled.
299 * In this case we *never* got WRITE_WAKEUP event,
300 * if we did not request it before write operation.
301 * 14 Oct 1994 Dmitry Gorodchanin.
302 */
303 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
304 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
305 sl->xleft = (pos - sl->xbuff) - actual;
306 sl->xhead = sl->xbuff + actual;
307 sl->dev->stats.tx_bytes += cf->can_dlc;
308}
309
310/* Write out any remaining transmit buffer. Scheduled when tty is writable */
311static void slcan_transmit(struct work_struct *work)
312{
313 struct slcan *sl = container_of(work, struct slcan, tx_work);
314 int actual;
315
316 spin_lock_bh(&sl->lock);
317 /* First make sure we're connected. */
318 if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
319 spin_unlock_bh(&sl->lock);
320 return;
321 }
322
323 if (sl->xleft <= 0) {
324 /* Now serial buffer is almost free & we can start
325 * transmission of another packet */
326 sl->dev->stats.tx_packets++;
327 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
328 spin_unlock_bh(&sl->lock);
329 netif_wake_queue(sl->dev);
330 return;
331 }
332
333 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
334 sl->xleft -= actual;
335 sl->xhead += actual;
336 spin_unlock_bh(&sl->lock);
337}
338
339/*
340 * Called by the driver when there's room for more data.
341 * Schedule the transmit.
342 */
343static void slcan_write_wakeup(struct tty_struct *tty)
344{
345 struct slcan *sl;
346
347 rcu_read_lock();
348 sl = rcu_dereference(tty->disc_data);
349 if (sl)
350 schedule_work(&sl->tx_work);
351 rcu_read_unlock();
352}
353
354/* Send a can_frame to a TTY queue. */
355static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
356{
357 struct slcan *sl = netdev_priv(dev);
358
359 if (skb->len != CAN_MTU)
360 goto out;
361
362 spin_lock(&sl->lock);
363 if (!netif_running(dev)) {
364 spin_unlock(&sl->lock);
365 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
366 goto out;
367 }
368 if (sl->tty == NULL) {
369 spin_unlock(&sl->lock);
370 goto out;
371 }
372
373 netif_stop_queue(sl->dev);
374 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
375 spin_unlock(&sl->lock);
376
377out:
378 kfree_skb(skb);
379 return NETDEV_TX_OK;
380}
381
382
383/******************************************
384 * Routines looking at netdevice side.
385 ******************************************/
386
387/* Netdevice UP -> DOWN routine */
388static int slc_close(struct net_device *dev)
389{
390 struct slcan *sl = netdev_priv(dev);
391
392 spin_lock_bh(&sl->lock);
393 if (sl->tty) {
394 /* TTY discipline is running. */
395 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
396 }
397 netif_stop_queue(dev);
398 sl->rcount = 0;
399 sl->xleft = 0;
400 spin_unlock_bh(&sl->lock);
401
402 return 0;
403}
404
405/* Netdevice DOWN -> UP routine */
406static int slc_open(struct net_device *dev)
407{
408 struct slcan *sl = netdev_priv(dev);
409
410 if (sl->tty == NULL)
411 return -ENODEV;
412
413 sl->flags &= (1 << SLF_INUSE);
414 netif_start_queue(dev);
415 return 0;
416}
417
418/* Hook the destructor so we can free slcan devs at the right point in time */
419static void slc_free_netdev(struct net_device *dev)
420{
421 int i = dev->base_addr;
422
423 slcan_devs[i] = NULL;
424}
425
426static int slcan_change_mtu(struct net_device *dev, int new_mtu)
427{
428 return -EINVAL;
429}
430
431static const struct net_device_ops slc_netdev_ops = {
432 .ndo_open = slc_open,
433 .ndo_stop = slc_close,
434 .ndo_start_xmit = slc_xmit,
435 .ndo_change_mtu = slcan_change_mtu,
436};
437
438static void slc_setup(struct net_device *dev)
439{
440 dev->netdev_ops = &slc_netdev_ops;
441 dev->needs_free_netdev = true;
442 dev->priv_destructor = slc_free_netdev;
443
444 dev->hard_header_len = 0;
445 dev->addr_len = 0;
446 dev->tx_queue_len = 10;
447
448 dev->mtu = CAN_MTU;
449 dev->type = ARPHRD_CAN;
450
451 /* New-style flags. */
452 dev->flags = IFF_NOARP;
453 dev->features = NETIF_F_HW_CSUM;
454}
455
456/******************************************
457 Routines looking at TTY side.
458 ******************************************/
459
460/*
461 * Handle the 'receiver data ready' interrupt.
462 * This function is called by the 'tty_io' module in the kernel when
463 * a block of SLCAN data has been received, which can now be decapsulated
464 * and sent on to some IP layer for further processing. This will not
465 * be re-entered while running but other ldisc functions may be called
466 * in parallel
467 */
468
469static void slcan_receive_buf(struct tty_struct *tty,
470 const unsigned char *cp, char *fp, int count)
471{
472 struct slcan *sl = (struct slcan *) tty->disc_data;
473
474 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
475 return;
476
477 /* Read the characters out of the buffer */
478 while (count--) {
479 if (fp && *fp++) {
480 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
481 sl->dev->stats.rx_errors++;
482 cp++;
483 continue;
484 }
485 slcan_unesc(sl, *cp++);
486 }
487}
488
489/************************************
490 * slcan_open helper routines.
491 ************************************/
492
493/* Collect hanged up channels */
494static void slc_sync(void)
495{
496 int i;
497 struct net_device *dev;
498 struct slcan *sl;
499
500 for (i = 0; i < maxdev; i++) {
501 dev = slcan_devs[i];
502 if (dev == NULL)
503 break;
504
505 sl = netdev_priv(dev);
506 if (sl->tty)
507 continue;
508 if (dev->flags & IFF_UP)
509 dev_close(dev);
510 }
511}
512
513/* Find a free SLCAN channel, and link in this `tty' line. */
514static struct slcan *slc_alloc(void)
515{
516 int i;
517 char name[IFNAMSIZ];
518 struct net_device *dev = NULL;
519 struct slcan *sl;
520 int size;
521
522 for (i = 0; i < maxdev; i++) {
523 dev = slcan_devs[i];
524 if (dev == NULL)
525 break;
526
527 }
528
529 /* Sorry, too many, all slots in use */
530 if (i >= maxdev)
531 return NULL;
532
533 sprintf(name, "slcan%d", i);
534 size = ALIGN(sizeof(*sl), NETDEV_ALIGN) + sizeof(struct can_ml_priv);
535 dev = alloc_netdev(size, name, NET_NAME_UNKNOWN, slc_setup);
536 if (!dev)
537 return NULL;
538
539 dev->base_addr = i;
540 sl = netdev_priv(dev);
541 dev->ml_priv = (void *)sl + ALIGN(sizeof(*sl), NETDEV_ALIGN);
542
543 /* Initialize channel control data */
544 sl->magic = SLCAN_MAGIC;
545 sl->dev = dev;
546 spin_lock_init(&sl->lock);
547 INIT_WORK(&sl->tx_work, slcan_transmit);
548 slcan_devs[i] = dev;
549
550 return sl;
551}
552
553/*
554 * Open the high-level part of the SLCAN channel.
555 * This function is called by the TTY module when the
556 * SLCAN line discipline is called for. Because we are
557 * sure the tty line exists, we only have to link it to
558 * a free SLCAN channel...
559 *
560 * Called in process context serialized from other ldisc calls.
561 */
562
563static int slcan_open(struct tty_struct *tty)
564{
565 struct slcan *sl;
566 int err;
567
568 if (!capable(CAP_NET_ADMIN))
569 return -EPERM;
570
571 if (tty->ops->write == NULL)
572 return -EOPNOTSUPP;
573
574 /* RTnetlink lock is misused here to serialize concurrent
575 opens of slcan channels. There are better ways, but it is
576 the simplest one.
577 */
578 rtnl_lock();
579
580 /* Collect hanged up channels. */
581 slc_sync();
582
583 sl = tty->disc_data;
584
585 err = -EEXIST;
586 /* First make sure we're not already connected. */
587 if (sl && sl->magic == SLCAN_MAGIC)
588 goto err_exit;
589
590 /* OK. Find a free SLCAN channel to use. */
591 err = -ENFILE;
592 sl = slc_alloc();
593 if (sl == NULL)
594 goto err_exit;
595
596 sl->tty = tty;
597 tty->disc_data = sl;
598
599 if (!test_bit(SLF_INUSE, &sl->flags)) {
600 /* Perform the low-level SLCAN initialization. */
601 sl->rcount = 0;
602 sl->xleft = 0;
603
604 set_bit(SLF_INUSE, &sl->flags);
605
606 err = register_netdevice(sl->dev);
607 if (err)
608 goto err_free_chan;
609 }
610
611 /* Done. We have linked the TTY line to a channel. */
612 rtnl_unlock();
613 tty->receive_room = 65536; /* We don't flow control */
614
615 /* TTY layer expects 0 on success */
616 return 0;
617
618err_free_chan:
619 sl->tty = NULL;
620 tty->disc_data = NULL;
621 clear_bit(SLF_INUSE, &sl->flags);
622 slc_free_netdev(sl->dev);
623 /* do not call free_netdev before rtnl_unlock */
624 rtnl_unlock();
625 free_netdev(sl->dev);
626 return err;
627
628err_exit:
629 rtnl_unlock();
630
631 /* Count references from TTY module */
632 return err;
633}
634
635/*
636 * Close down a SLCAN channel.
637 * This means flushing out any pending queues, and then returning. This
638 * call is serialized against other ldisc functions.
639 *
640 * We also use this method for a hangup event.
641 */
642
643static void slcan_close(struct tty_struct *tty)
644{
645 struct slcan *sl = (struct slcan *) tty->disc_data;
646
647 /* First make sure we're connected. */
648 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
649 return;
650
651 spin_lock_bh(&sl->lock);
652 rcu_assign_pointer(tty->disc_data, NULL);
653 sl->tty = NULL;
654 spin_unlock_bh(&sl->lock);
655
656 synchronize_rcu();
657 flush_work(&sl->tx_work);
658
659 /* Flush network side */
660 unregister_netdev(sl->dev);
661 /* This will complete via sl_free_netdev */
662}
663
664static int slcan_hangup(struct tty_struct *tty)
665{
666 slcan_close(tty);
667 return 0;
668}
669
670/* Perform I/O control on an active SLCAN channel. */
671static int slcan_ioctl(struct tty_struct *tty, struct file *file,
672 unsigned int cmd, unsigned long arg)
673{
674 struct slcan *sl = (struct slcan *) tty->disc_data;
675 unsigned int tmp;
676
677 /* First make sure we're connected. */
678 if (!sl || sl->magic != SLCAN_MAGIC)
679 return -EINVAL;
680
681 switch (cmd) {
682 case SIOCGIFNAME:
683 tmp = strlen(sl->dev->name) + 1;
684 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
685 return -EFAULT;
686 return 0;
687
688 case SIOCSIFHWADDR:
689 return -EINVAL;
690
691 default:
692 return tty_mode_ioctl(tty, file, cmd, arg);
693 }
694}
695
696static struct tty_ldisc_ops slc_ldisc = {
697 .owner = THIS_MODULE,
698 .magic = TTY_LDISC_MAGIC,
699 .name = "slcan",
700 .open = slcan_open,
701 .close = slcan_close,
702 .hangup = slcan_hangup,
703 .ioctl = slcan_ioctl,
704 .receive_buf = slcan_receive_buf,
705 .write_wakeup = slcan_write_wakeup,
706};
707
708static int __init slcan_init(void)
709{
710 int status;
711
712 if (maxdev < 4)
713 maxdev = 4; /* Sanity */
714
715 pr_info("slcan: serial line CAN interface driver\n");
716 pr_info("slcan: %d dynamic interface channels.\n", maxdev);
717
718 slcan_devs = kcalloc(maxdev, sizeof(struct net_device *), GFP_KERNEL);
719 if (!slcan_devs)
720 return -ENOMEM;
721
722 /* Fill in our line protocol discipline, and register it */
723 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
724 if (status) {
725 printk(KERN_ERR "slcan: can't register line discipline\n");
726 kfree(slcan_devs);
727 }
728 return status;
729}
730
731static void __exit slcan_exit(void)
732{
733 int i;
734 struct net_device *dev;
735 struct slcan *sl;
736 unsigned long timeout = jiffies + HZ;
737 int busy = 0;
738
739 if (slcan_devs == NULL)
740 return;
741
742 /* First of all: check for active disciplines and hangup them.
743 */
744 do {
745 if (busy)
746 msleep_interruptible(100);
747
748 busy = 0;
749 for (i = 0; i < maxdev; i++) {
750 dev = slcan_devs[i];
751 if (!dev)
752 continue;
753 sl = netdev_priv(dev);
754 spin_lock_bh(&sl->lock);
755 if (sl->tty) {
756 busy++;
757 tty_hangup(sl->tty);
758 }
759 spin_unlock_bh(&sl->lock);
760 }
761 } while (busy && time_before(jiffies, timeout));
762
763 /* FIXME: hangup is async so we should wait when doing this second
764 phase */
765
766 for (i = 0; i < maxdev; i++) {
767 dev = slcan_devs[i];
768 if (!dev)
769 continue;
770 slcan_devs[i] = NULL;
771
772 sl = netdev_priv(dev);
773 if (sl->tty) {
774 printk(KERN_ERR "%s: tty discipline still running\n",
775 dev->name);
776 }
777
778 unregister_netdev(dev);
779 }
780
781 kfree(slcan_devs);
782 slcan_devs = NULL;
783
784 i = tty_unregister_ldisc(N_SLCAN);
785 if (i)
786 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
787}
788
789module_init(slcan_init);
790module_exit(slcan_exit);