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
59 MODULE_ALIAS_LDISC(N_SLCAN);
60 MODULE_DESCRIPTION("serial line CAN interface");
61 MODULE_LICENSE("GPL");
62 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
63
64 #define SLCAN_MAGIC 0x53CA
65
66 static int maxdev = 10; /* MAX number of SLCAN channels;
67 This can be overridden with
68 insmod slcan.ko maxdev=nnn */
69 module_param(maxdev, int, 0);
70 MODULE_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
79 struct 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
100 static 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 */
slc_bump(struct slcan * sl)142 static 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 memset(&cf, 0, sizeof(cf));
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 /* RTR frames may have a dlc > 0 but they never have any data bytes */
190 if (!(cf.can_id & CAN_RTR_FLAG)) {
191 for (i = 0; i < cf.can_dlc; i++) {
192 tmp = hex_to_bin(*cmd++);
193 if (tmp < 0)
194 return;
195 cf.data[i] = (tmp << 4);
196 tmp = hex_to_bin(*cmd++);
197 if (tmp < 0)
198 return;
199 cf.data[i] |= tmp;
200 }
201 }
202
203 skb = dev_alloc_skb(sizeof(struct can_frame) +
204 sizeof(struct can_skb_priv));
205 if (!skb)
206 return;
207
208 skb->dev = sl->dev;
209 skb->protocol = htons(ETH_P_CAN);
210 skb->pkt_type = PACKET_BROADCAST;
211 skb->ip_summed = CHECKSUM_UNNECESSARY;
212
213 can_skb_reserve(skb);
214 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
215 can_skb_prv(skb)->skbcnt = 0;
216
217 skb_put_data(skb, &cf, sizeof(struct can_frame));
218
219 sl->dev->stats.rx_packets++;
220 sl->dev->stats.rx_bytes += cf.can_dlc;
221 netif_rx_ni(skb);
222 }
223
224 /* parse tty input stream */
slcan_unesc(struct slcan * sl,unsigned char s)225 static void slcan_unesc(struct slcan *sl, unsigned char s)
226 {
227 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
228 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
229 (sl->rcount > 4)) {
230 slc_bump(sl);
231 }
232 sl->rcount = 0;
233 } else {
234 if (!test_bit(SLF_ERROR, &sl->flags)) {
235 if (sl->rcount < SLC_MTU) {
236 sl->rbuff[sl->rcount++] = s;
237 return;
238 } else {
239 sl->dev->stats.rx_over_errors++;
240 set_bit(SLF_ERROR, &sl->flags);
241 }
242 }
243 }
244 }
245
246 /************************************************************************
247 * STANDARD SLCAN ENCAPSULATION *
248 ************************************************************************/
249
250 /* Encapsulate one can_frame and stuff into a TTY queue. */
slc_encaps(struct slcan * sl,struct can_frame * cf)251 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
252 {
253 int actual, i;
254 unsigned char *pos;
255 unsigned char *endpos;
256 canid_t id = cf->can_id;
257
258 pos = sl->xbuff;
259
260 if (cf->can_id & CAN_RTR_FLAG)
261 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
262 else
263 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
264
265 /* determine number of chars for the CAN-identifier */
266 if (cf->can_id & CAN_EFF_FLAG) {
267 id &= CAN_EFF_MASK;
268 endpos = pos + SLC_EFF_ID_LEN;
269 } else {
270 *pos |= 0x20; /* convert R/T to lower case for SFF */
271 id &= CAN_SFF_MASK;
272 endpos = pos + SLC_SFF_ID_LEN;
273 }
274
275 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
276 pos++;
277 while (endpos >= pos) {
278 *endpos-- = hex_asc_upper[id & 0xf];
279 id >>= 4;
280 }
281
282 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
283
284 *pos++ = cf->can_dlc + '0';
285
286 /* RTR frames may have a dlc > 0 but they never have any data bytes */
287 if (!(cf->can_id & CAN_RTR_FLAG)) {
288 for (i = 0; i < cf->can_dlc; i++)
289 pos = hex_byte_pack_upper(pos, cf->data[i]);
290 }
291
292 *pos++ = '\r';
293
294 /* Order of next two lines is *very* important.
295 * When we are sending a little amount of data,
296 * the transfer may be completed inside the ops->write()
297 * routine, because it's running with interrupts enabled.
298 * In this case we *never* got WRITE_WAKEUP event,
299 * if we did not request it before write operation.
300 * 14 Oct 1994 Dmitry Gorodchanin.
301 */
302 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
303 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
304 sl->xleft = (pos - sl->xbuff) - actual;
305 sl->xhead = sl->xbuff + actual;
306 sl->dev->stats.tx_bytes += cf->can_dlc;
307 }
308
309 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
slcan_transmit(struct work_struct * work)310 static void slcan_transmit(struct work_struct *work)
311 {
312 struct slcan *sl = container_of(work, struct slcan, tx_work);
313 int actual;
314
315 spin_lock_bh(&sl->lock);
316 /* First make sure we're connected. */
317 if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
318 spin_unlock_bh(&sl->lock);
319 return;
320 }
321
322 if (sl->xleft <= 0) {
323 /* Now serial buffer is almost free & we can start
324 * transmission of another packet */
325 sl->dev->stats.tx_packets++;
326 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
327 spin_unlock_bh(&sl->lock);
328 netif_wake_queue(sl->dev);
329 return;
330 }
331
332 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
333 sl->xleft -= actual;
334 sl->xhead += actual;
335 spin_unlock_bh(&sl->lock);
336 }
337
338 /*
339 * Called by the driver when there's room for more data.
340 * Schedule the transmit.
341 */
slcan_write_wakeup(struct tty_struct * tty)342 static void slcan_write_wakeup(struct tty_struct *tty)
343 {
344 struct slcan *sl;
345
346 rcu_read_lock();
347 sl = rcu_dereference(tty->disc_data);
348 if (!sl)
349 goto out;
350
351 schedule_work(&sl->tx_work);
352 out:
353 rcu_read_unlock();
354 }
355
356 /* Send a can_frame to a TTY queue. */
slc_xmit(struct sk_buff * skb,struct net_device * dev)357 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
358 {
359 struct slcan *sl = netdev_priv(dev);
360
361 if (skb->len != CAN_MTU)
362 goto out;
363
364 spin_lock(&sl->lock);
365 if (!netif_running(dev)) {
366 spin_unlock(&sl->lock);
367 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
368 goto out;
369 }
370 if (sl->tty == NULL) {
371 spin_unlock(&sl->lock);
372 goto out;
373 }
374
375 netif_stop_queue(sl->dev);
376 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
377 spin_unlock(&sl->lock);
378
379 out:
380 kfree_skb(skb);
381 return NETDEV_TX_OK;
382 }
383
384
385 /******************************************
386 * Routines looking at netdevice side.
387 ******************************************/
388
389 /* Netdevice UP -> DOWN routine */
slc_close(struct net_device * dev)390 static int slc_close(struct net_device *dev)
391 {
392 struct slcan *sl = netdev_priv(dev);
393
394 spin_lock_bh(&sl->lock);
395 if (sl->tty) {
396 /* TTY discipline is running. */
397 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
398 }
399 netif_stop_queue(dev);
400 sl->rcount = 0;
401 sl->xleft = 0;
402 spin_unlock_bh(&sl->lock);
403
404 return 0;
405 }
406
407 /* Netdevice DOWN -> UP routine */
slc_open(struct net_device * dev)408 static int slc_open(struct net_device *dev)
409 {
410 struct slcan *sl = netdev_priv(dev);
411
412 if (sl->tty == NULL)
413 return -ENODEV;
414
415 sl->flags &= (1 << SLF_INUSE);
416 netif_start_queue(dev);
417 return 0;
418 }
419
420 /* Hook the destructor so we can free slcan devs at the right point in time */
slc_free_netdev(struct net_device * dev)421 static void slc_free_netdev(struct net_device *dev)
422 {
423 int i = dev->base_addr;
424
425 slcan_devs[i] = NULL;
426 }
427
slcan_change_mtu(struct net_device * dev,int new_mtu)428 static int slcan_change_mtu(struct net_device *dev, int new_mtu)
429 {
430 return -EINVAL;
431 }
432
433 static const struct net_device_ops slc_netdev_ops = {
434 .ndo_open = slc_open,
435 .ndo_stop = slc_close,
436 .ndo_start_xmit = slc_xmit,
437 .ndo_change_mtu = slcan_change_mtu,
438 };
439
slc_setup(struct net_device * dev)440 static void slc_setup(struct net_device *dev)
441 {
442 dev->netdev_ops = &slc_netdev_ops;
443 dev->needs_free_netdev = true;
444 dev->priv_destructor = slc_free_netdev;
445
446 dev->hard_header_len = 0;
447 dev->addr_len = 0;
448 dev->tx_queue_len = 10;
449
450 dev->mtu = CAN_MTU;
451 dev->type = ARPHRD_CAN;
452
453 /* New-style flags. */
454 dev->flags = IFF_NOARP;
455 dev->features = NETIF_F_HW_CSUM;
456 }
457
458 /******************************************
459 Routines looking at TTY side.
460 ******************************************/
461
462 /*
463 * Handle the 'receiver data ready' interrupt.
464 * This function is called by the 'tty_io' module in the kernel when
465 * a block of SLCAN data has been received, which can now be decapsulated
466 * and sent on to some IP layer for further processing. This will not
467 * be re-entered while running but other ldisc functions may be called
468 * in parallel
469 */
470
slcan_receive_buf(struct tty_struct * tty,const unsigned char * cp,char * fp,int count)471 static void slcan_receive_buf(struct tty_struct *tty,
472 const unsigned char *cp, char *fp, int count)
473 {
474 struct slcan *sl = (struct slcan *) tty->disc_data;
475
476 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
477 return;
478
479 /* Read the characters out of the buffer */
480 while (count--) {
481 if (fp && *fp++) {
482 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
483 sl->dev->stats.rx_errors++;
484 cp++;
485 continue;
486 }
487 slcan_unesc(sl, *cp++);
488 }
489 }
490
491 /************************************
492 * slcan_open helper routines.
493 ************************************/
494
495 /* Collect hanged up channels */
slc_sync(void)496 static void slc_sync(void)
497 {
498 int i;
499 struct net_device *dev;
500 struct slcan *sl;
501
502 for (i = 0; i < maxdev; i++) {
503 dev = slcan_devs[i];
504 if (dev == NULL)
505 break;
506
507 sl = netdev_priv(dev);
508 if (sl->tty)
509 continue;
510 if (dev->flags & IFF_UP)
511 dev_close(dev);
512 }
513 }
514
515 /* Find a free SLCAN channel, and link in this `tty' line. */
slc_alloc(void)516 static struct slcan *slc_alloc(void)
517 {
518 int i;
519 char name[IFNAMSIZ];
520 struct net_device *dev = NULL;
521 struct slcan *sl;
522
523 for (i = 0; i < maxdev; i++) {
524 dev = slcan_devs[i];
525 if (dev == NULL)
526 break;
527
528 }
529
530 /* Sorry, too many, all slots in use */
531 if (i >= maxdev)
532 return NULL;
533
534 sprintf(name, "slcan%d", i);
535 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, slc_setup);
536 if (!dev)
537 return NULL;
538
539 dev->base_addr = i;
540 sl = netdev_priv(dev);
541
542 /* Initialize channel control data */
543 sl->magic = SLCAN_MAGIC;
544 sl->dev = dev;
545 spin_lock_init(&sl->lock);
546 INIT_WORK(&sl->tx_work, slcan_transmit);
547 slcan_devs[i] = dev;
548
549 return sl;
550 }
551
552 /*
553 * Open the high-level part of the SLCAN channel.
554 * This function is called by the TTY module when the
555 * SLCAN line discipline is called for. Because we are
556 * sure the tty line exists, we only have to link it to
557 * a free SLCAN channel...
558 *
559 * Called in process context serialized from other ldisc calls.
560 */
561
slcan_open(struct tty_struct * tty)562 static int slcan_open(struct tty_struct *tty)
563 {
564 struct slcan *sl;
565 int err;
566
567 if (!capable(CAP_NET_ADMIN))
568 return -EPERM;
569
570 if (tty->ops->write == NULL)
571 return -EOPNOTSUPP;
572
573 /* RTnetlink lock is misused here to serialize concurrent
574 opens of slcan channels. There are better ways, but it is
575 the simplest one.
576 */
577 rtnl_lock();
578
579 /* Collect hanged up channels. */
580 slc_sync();
581
582 sl = tty->disc_data;
583
584 err = -EEXIST;
585 /* First make sure we're not already connected. */
586 if (sl && sl->magic == SLCAN_MAGIC)
587 goto err_exit;
588
589 /* OK. Find a free SLCAN channel to use. */
590 err = -ENFILE;
591 sl = slc_alloc();
592 if (sl == NULL)
593 goto err_exit;
594
595 sl->tty = tty;
596 tty->disc_data = sl;
597
598 if (!test_bit(SLF_INUSE, &sl->flags)) {
599 /* Perform the low-level SLCAN initialization. */
600 sl->rcount = 0;
601 sl->xleft = 0;
602
603 set_bit(SLF_INUSE, &sl->flags);
604
605 err = register_netdevice(sl->dev);
606 if (err)
607 goto err_free_chan;
608 }
609
610 /* Done. We have linked the TTY line to a channel. */
611 rtnl_unlock();
612 tty->receive_room = 65536; /* We don't flow control */
613
614 /* TTY layer expects 0 on success */
615 return 0;
616
617 err_free_chan:
618 sl->tty = NULL;
619 tty->disc_data = NULL;
620 clear_bit(SLF_INUSE, &sl->flags);
621 slc_free_netdev(sl->dev);
622 /* do not call free_netdev before rtnl_unlock */
623 rtnl_unlock();
624 free_netdev(sl->dev);
625 return err;
626
627 err_exit:
628 rtnl_unlock();
629
630 /* Count references from TTY module */
631 return err;
632 }
633
634 /*
635 * Close down a SLCAN channel.
636 * This means flushing out any pending queues, and then returning. This
637 * call is serialized against other ldisc functions.
638 *
639 * We also use this method for a hangup event.
640 */
641
slcan_close(struct tty_struct * tty)642 static void slcan_close(struct tty_struct *tty)
643 {
644 struct slcan *sl = (struct slcan *) tty->disc_data;
645
646 /* First make sure we're connected. */
647 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
648 return;
649
650 spin_lock_bh(&sl->lock);
651 rcu_assign_pointer(tty->disc_data, NULL);
652 sl->tty = NULL;
653 spin_unlock_bh(&sl->lock);
654
655 synchronize_rcu();
656 flush_work(&sl->tx_work);
657
658 /* Flush network side */
659 unregister_netdev(sl->dev);
660 /* This will complete via sl_free_netdev */
661 }
662
slcan_hangup(struct tty_struct * tty)663 static int slcan_hangup(struct tty_struct *tty)
664 {
665 slcan_close(tty);
666 return 0;
667 }
668
669 /* Perform I/O control on an active SLCAN channel. */
slcan_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)670 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
671 unsigned int cmd, unsigned long arg)
672 {
673 struct slcan *sl = (struct slcan *) tty->disc_data;
674 unsigned int tmp;
675
676 /* First make sure we're connected. */
677 if (!sl || sl->magic != SLCAN_MAGIC)
678 return -EINVAL;
679
680 switch (cmd) {
681 case SIOCGIFNAME:
682 tmp = strlen(sl->dev->name) + 1;
683 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
684 return -EFAULT;
685 return 0;
686
687 case SIOCSIFHWADDR:
688 return -EINVAL;
689
690 default:
691 return tty_mode_ioctl(tty, file, cmd, arg);
692 }
693 }
694
695 static struct tty_ldisc_ops slc_ldisc = {
696 .owner = THIS_MODULE,
697 .magic = TTY_LDISC_MAGIC,
698 .name = "slcan",
699 .open = slcan_open,
700 .close = slcan_close,
701 .hangup = slcan_hangup,
702 .ioctl = slcan_ioctl,
703 .receive_buf = slcan_receive_buf,
704 .write_wakeup = slcan_write_wakeup,
705 };
706
slcan_init(void)707 static int __init slcan_init(void)
708 {
709 int status;
710
711 if (maxdev < 4)
712 maxdev = 4; /* Sanity */
713
714 pr_info("slcan: serial line CAN interface driver\n");
715 pr_info("slcan: %d dynamic interface channels.\n", maxdev);
716
717 slcan_devs = kcalloc(maxdev, sizeof(struct net_device *), GFP_KERNEL);
718 if (!slcan_devs)
719 return -ENOMEM;
720
721 /* Fill in our line protocol discipline, and register it */
722 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
723 if (status) {
724 printk(KERN_ERR "slcan: can't register line discipline\n");
725 kfree(slcan_devs);
726 }
727 return status;
728 }
729
slcan_exit(void)730 static void __exit slcan_exit(void)
731 {
732 int i;
733 struct net_device *dev;
734 struct slcan *sl;
735 unsigned long timeout = jiffies + HZ;
736 int busy = 0;
737
738 if (slcan_devs == NULL)
739 return;
740
741 /* First of all: check for active disciplines and hangup them.
742 */
743 do {
744 if (busy)
745 msleep_interruptible(100);
746
747 busy = 0;
748 for (i = 0; i < maxdev; i++) {
749 dev = slcan_devs[i];
750 if (!dev)
751 continue;
752 sl = netdev_priv(dev);
753 spin_lock_bh(&sl->lock);
754 if (sl->tty) {
755 busy++;
756 tty_hangup(sl->tty);
757 }
758 spin_unlock_bh(&sl->lock);
759 }
760 } while (busy && time_before(jiffies, timeout));
761
762 /* FIXME: hangup is async so we should wait when doing this second
763 phase */
764
765 for (i = 0; i < maxdev; i++) {
766 dev = slcan_devs[i];
767 if (!dev)
768 continue;
769 slcan_devs[i] = NULL;
770
771 sl = netdev_priv(dev);
772 if (sl->tty) {
773 printk(KERN_ERR "%s: tty discipline still running\n",
774 dev->name);
775 }
776
777 unregister_netdev(dev);
778 }
779
780 kfree(slcan_devs);
781 slcan_devs = NULL;
782
783 i = tty_unregister_ldisc(N_SLCAN);
784 if (i)
785 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
786 }
787
788 module_init(slcan_init);
789 module_exit(slcan_exit);
790