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 static __initconst const char banner[] =
60 KERN_INFO "slcan: serial line CAN interface driver\n";
61
62 MODULE_ALIAS_LDISC(N_SLCAN);
63 MODULE_DESCRIPTION("serial line CAN interface");
64 MODULE_LICENSE("GPL");
65 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
66
67 #define SLCAN_MAGIC 0x53CA
68
69 static int maxdev = 10; /* MAX number of SLCAN channels;
70 This can be overridden with
71 insmod slcan.ko maxdev=nnn */
72 module_param(maxdev, int, 0);
73 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
74
75 /* maximum rx buffer len: extended CAN frame with timestamp */
76 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
77
78 #define SLC_CMD_LEN 1
79 #define SLC_SFF_ID_LEN 3
80 #define SLC_EFF_ID_LEN 8
81
82 struct slcan {
83 int magic;
84
85 /* Various fields. */
86 struct tty_struct *tty; /* ptr to TTY structure */
87 struct net_device *dev; /* easy for intr handling */
88 spinlock_t lock;
89 struct work_struct tx_work; /* Flushes transmit buffer */
90
91 /* These are pointers to the malloc()ed frame buffers. */
92 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
93 int rcount; /* received chars counter */
94 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
95 unsigned char *xhead; /* pointer to next XMIT byte */
96 int xleft; /* bytes left in XMIT queue */
97
98 unsigned long flags; /* Flag values/ mode etc */
99 #define SLF_INUSE 0 /* Channel in use */
100 #define SLF_ERROR 1 /* Parity, etc. error */
101 };
102
103 static struct net_device **slcan_devs;
104
105 /************************************************************************
106 * SLCAN ENCAPSULATION FORMAT *
107 ************************************************************************/
108
109 /*
110 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
111 * frame format) a data length code (can_dlc) which can be from 0 to 8
112 * and up to <can_dlc> data bytes as payload.
113 * Additionally a CAN frame may become a remote transmission frame if the
114 * RTR-bit is set. This causes another ECU to send a CAN frame with the
115 * given can_id.
116 *
117 * The SLCAN ASCII representation of these different frame types is:
118 * <type> <id> <dlc> <data>*
119 *
120 * Extended frames (29 bit) are defined by capital characters in the type.
121 * RTR frames are defined as 'r' types - normal frames have 't' type:
122 * t => 11 bit data frame
123 * r => 11 bit RTR frame
124 * T => 29 bit data frame
125 * R => 29 bit RTR frame
126 *
127 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
128 * The <dlc> is a one byte ASCII number ('0' - '8')
129 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
130 *
131 * Examples:
132 *
133 * t1230 : can_id 0x123, can_dlc 0, no data
134 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
135 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
136 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
137 *
138 */
139
140 /************************************************************************
141 * STANDARD SLCAN DECAPSULATION *
142 ************************************************************************/
143
144 /* Send one completely decapsulated can_frame to the network layer */
slc_bump(struct slcan * sl)145 static void slc_bump(struct slcan *sl)
146 {
147 struct sk_buff *skb;
148 struct can_frame cf;
149 int i, tmp;
150 u32 tmpid;
151 char *cmd = sl->rbuff;
152
153 cf.can_id = 0;
154
155 switch (*cmd) {
156 case 'r':
157 cf.can_id = CAN_RTR_FLAG;
158 /* fallthrough */
159 case 't':
160 /* store dlc ASCII value and terminate SFF CAN ID string */
161 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
162 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
163 /* point to payload data behind the dlc */
164 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
165 break;
166 case 'R':
167 cf.can_id = CAN_RTR_FLAG;
168 /* fallthrough */
169 case 'T':
170 cf.can_id |= CAN_EFF_FLAG;
171 /* store dlc ASCII value and terminate EFF CAN ID string */
172 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
173 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
174 /* point to payload data behind the dlc */
175 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
176 break;
177 default:
178 return;
179 }
180
181 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
182 return;
183
184 cf.can_id |= tmpid;
185
186 /* get can_dlc from sanitized ASCII value */
187 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
188 cf.can_dlc -= '0';
189 else
190 return;
191
192 *(u64 *) (&cf.data) = 0; /* clear payload */
193
194 /* RTR frames may have a dlc > 0 but they never have any data bytes */
195 if (!(cf.can_id & CAN_RTR_FLAG)) {
196 for (i = 0; i < cf.can_dlc; i++) {
197 tmp = hex_to_bin(*cmd++);
198 if (tmp < 0)
199 return;
200 cf.data[i] = (tmp << 4);
201 tmp = hex_to_bin(*cmd++);
202 if (tmp < 0)
203 return;
204 cf.data[i] |= tmp;
205 }
206 }
207
208 skb = dev_alloc_skb(sizeof(struct can_frame) +
209 sizeof(struct can_skb_priv));
210 if (!skb)
211 return;
212
213 skb->dev = sl->dev;
214 skb->protocol = htons(ETH_P_CAN);
215 skb->pkt_type = PACKET_BROADCAST;
216 skb->ip_summed = CHECKSUM_UNNECESSARY;
217
218 can_skb_reserve(skb);
219 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
220
221 memcpy(skb_put(skb, sizeof(struct can_frame)),
222 &cf, sizeof(struct can_frame));
223 netif_rx_ni(skb);
224
225 sl->dev->stats.rx_packets++;
226 sl->dev->stats.rx_bytes += cf.can_dlc;
227 }
228
229 /* parse tty input stream */
slcan_unesc(struct slcan * sl,unsigned char s)230 static void slcan_unesc(struct slcan *sl, unsigned char s)
231 {
232 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
233 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
234 (sl->rcount > 4)) {
235 slc_bump(sl);
236 }
237 sl->rcount = 0;
238 } else {
239 if (!test_bit(SLF_ERROR, &sl->flags)) {
240 if (sl->rcount < SLC_MTU) {
241 sl->rbuff[sl->rcount++] = s;
242 return;
243 } else {
244 sl->dev->stats.rx_over_errors++;
245 set_bit(SLF_ERROR, &sl->flags);
246 }
247 }
248 }
249 }
250
251 /************************************************************************
252 * STANDARD SLCAN ENCAPSULATION *
253 ************************************************************************/
254
255 /* Encapsulate one can_frame and stuff into a TTY queue. */
slc_encaps(struct slcan * sl,struct can_frame * cf)256 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
257 {
258 int actual, i;
259 unsigned char *pos;
260 unsigned char *endpos;
261 canid_t id = cf->can_id;
262
263 pos = sl->xbuff;
264
265 if (cf->can_id & CAN_RTR_FLAG)
266 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
267 else
268 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
269
270 /* determine number of chars for the CAN-identifier */
271 if (cf->can_id & CAN_EFF_FLAG) {
272 id &= CAN_EFF_MASK;
273 endpos = pos + SLC_EFF_ID_LEN;
274 } else {
275 *pos |= 0x20; /* convert R/T to lower case for SFF */
276 id &= CAN_SFF_MASK;
277 endpos = pos + SLC_SFF_ID_LEN;
278 }
279
280 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
281 pos++;
282 while (endpos >= pos) {
283 *endpos-- = hex_asc_upper[id & 0xf];
284 id >>= 4;
285 }
286
287 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
288
289 *pos++ = cf->can_dlc + '0';
290
291 /* RTR frames may have a dlc > 0 but they never have any data bytes */
292 if (!(cf->can_id & CAN_RTR_FLAG)) {
293 for (i = 0; i < cf->can_dlc; i++)
294 pos = hex_byte_pack_upper(pos, cf->data[i]);
295 }
296
297 *pos++ = '\r';
298
299 /* Order of next two lines is *very* important.
300 * When we are sending a little amount of data,
301 * the transfer may be completed inside the ops->write()
302 * routine, because it's running with interrupts enabled.
303 * In this case we *never* got WRITE_WAKEUP event,
304 * if we did not request it before write operation.
305 * 14 Oct 1994 Dmitry Gorodchanin.
306 */
307 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
308 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
309 sl->xleft = (pos - sl->xbuff) - actual;
310 sl->xhead = sl->xbuff + actual;
311 sl->dev->stats.tx_bytes += cf->can_dlc;
312 }
313
314 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
slcan_transmit(struct work_struct * work)315 static void slcan_transmit(struct work_struct *work)
316 {
317 struct slcan *sl = container_of(work, struct slcan, tx_work);
318 int actual;
319
320 spin_lock_bh(&sl->lock);
321 /* First make sure we're connected. */
322 if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
323 spin_unlock_bh(&sl->lock);
324 return;
325 }
326
327 if (sl->xleft <= 0) {
328 /* Now serial buffer is almost free & we can start
329 * transmission of another packet */
330 sl->dev->stats.tx_packets++;
331 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
332 spin_unlock_bh(&sl->lock);
333 netif_wake_queue(sl->dev);
334 return;
335 }
336
337 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
338 sl->xleft -= actual;
339 sl->xhead += actual;
340 spin_unlock_bh(&sl->lock);
341 }
342
343 /*
344 * Called by the driver when there's room for more data.
345 * Schedule the transmit.
346 */
slcan_write_wakeup(struct tty_struct * tty)347 static void slcan_write_wakeup(struct tty_struct *tty)
348 {
349 struct slcan *sl = tty->disc_data;
350
351 schedule_work(&sl->tx_work);
352 }
353
354 /* Send a can_frame to a TTY queue. */
slc_xmit(struct sk_buff * skb,struct net_device * dev)355 static 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 != sizeof(struct can_frame))
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
377 out:
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 */
slc_close(struct net_device * dev)388 static 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 */
slc_open(struct net_device * dev)406 static 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 */
slc_free_netdev(struct net_device * dev)419 static void slc_free_netdev(struct net_device *dev)
420 {
421 int i = dev->base_addr;
422 free_netdev(dev);
423 slcan_devs[i] = NULL;
424 }
425
slcan_change_mtu(struct net_device * dev,int new_mtu)426 static int slcan_change_mtu(struct net_device *dev, int new_mtu)
427 {
428 return -EINVAL;
429 }
430
431 static 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
slc_setup(struct net_device * dev)438 static void slc_setup(struct net_device *dev)
439 {
440 dev->netdev_ops = &slc_netdev_ops;
441 dev->destructor = slc_free_netdev;
442
443 dev->hard_header_len = 0;
444 dev->addr_len = 0;
445 dev->tx_queue_len = 10;
446
447 dev->mtu = sizeof(struct can_frame);
448 dev->type = ARPHRD_CAN;
449
450 /* New-style flags. */
451 dev->flags = IFF_NOARP;
452 dev->features = NETIF_F_HW_CSUM;
453 }
454
455 /******************************************
456 Routines looking at TTY side.
457 ******************************************/
458
459 /*
460 * Handle the 'receiver data ready' interrupt.
461 * This function is called by the 'tty_io' module in the kernel when
462 * a block of SLCAN data has been received, which can now be decapsulated
463 * and sent on to some IP layer for further processing. This will not
464 * be re-entered while running but other ldisc functions may be called
465 * in parallel
466 */
467
slcan_receive_buf(struct tty_struct * tty,const unsigned char * cp,char * fp,int count)468 static void slcan_receive_buf(struct tty_struct *tty,
469 const unsigned char *cp, char *fp, int count)
470 {
471 struct slcan *sl = (struct slcan *) tty->disc_data;
472
473 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
474 return;
475
476 /* Read the characters out of the buffer */
477 while (count--) {
478 if (fp && *fp++) {
479 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
480 sl->dev->stats.rx_errors++;
481 cp++;
482 continue;
483 }
484 slcan_unesc(sl, *cp++);
485 }
486 }
487
488 /************************************
489 * slcan_open helper routines.
490 ************************************/
491
492 /* Collect hanged up channels */
slc_sync(void)493 static void slc_sync(void)
494 {
495 int i;
496 struct net_device *dev;
497 struct slcan *sl;
498
499 for (i = 0; i < maxdev; i++) {
500 dev = slcan_devs[i];
501 if (dev == NULL)
502 break;
503
504 sl = netdev_priv(dev);
505 if (sl->tty)
506 continue;
507 if (dev->flags & IFF_UP)
508 dev_close(dev);
509 }
510 }
511
512 /* Find a free SLCAN channel, and link in this `tty' line. */
slc_alloc(dev_t line)513 static struct slcan *slc_alloc(dev_t line)
514 {
515 int i;
516 char name[IFNAMSIZ];
517 struct net_device *dev = NULL;
518 struct slcan *sl;
519
520 for (i = 0; i < maxdev; i++) {
521 dev = slcan_devs[i];
522 if (dev == NULL)
523 break;
524
525 }
526
527 /* Sorry, too many, all slots in use */
528 if (i >= maxdev)
529 return NULL;
530
531 sprintf(name, "slcan%d", i);
532 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, slc_setup);
533 if (!dev)
534 return NULL;
535
536 dev->base_addr = i;
537 sl = netdev_priv(dev);
538
539 /* Initialize channel control data */
540 sl->magic = SLCAN_MAGIC;
541 sl->dev = dev;
542 spin_lock_init(&sl->lock);
543 INIT_WORK(&sl->tx_work, slcan_transmit);
544 slcan_devs[i] = dev;
545
546 return sl;
547 }
548
549 /*
550 * Open the high-level part of the SLCAN channel.
551 * This function is called by the TTY module when the
552 * SLCAN line discipline is called for. Because we are
553 * sure the tty line exists, we only have to link it to
554 * a free SLCAN channel...
555 *
556 * Called in process context serialized from other ldisc calls.
557 */
558
slcan_open(struct tty_struct * tty)559 static int slcan_open(struct tty_struct *tty)
560 {
561 struct slcan *sl;
562 int err;
563
564 if (!capable(CAP_NET_ADMIN))
565 return -EPERM;
566
567 if (tty->ops->write == NULL)
568 return -EOPNOTSUPP;
569
570 /* RTnetlink lock is misused here to serialize concurrent
571 opens of slcan channels. There are better ways, but it is
572 the simplest one.
573 */
574 rtnl_lock();
575
576 /* Collect hanged up channels. */
577 slc_sync();
578
579 sl = tty->disc_data;
580
581 err = -EEXIST;
582 /* First make sure we're not already connected. */
583 if (sl && sl->magic == SLCAN_MAGIC)
584 goto err_exit;
585
586 /* OK. Find a free SLCAN channel to use. */
587 err = -ENFILE;
588 sl = slc_alloc(tty_devnum(tty));
589 if (sl == NULL)
590 goto err_exit;
591
592 sl->tty = tty;
593 tty->disc_data = sl;
594
595 if (!test_bit(SLF_INUSE, &sl->flags)) {
596 /* Perform the low-level SLCAN initialization. */
597 sl->rcount = 0;
598 sl->xleft = 0;
599
600 set_bit(SLF_INUSE, &sl->flags);
601
602 err = register_netdevice(sl->dev);
603 if (err)
604 goto err_free_chan;
605 }
606
607 /* Done. We have linked the TTY line to a channel. */
608 rtnl_unlock();
609 tty->receive_room = 65536; /* We don't flow control */
610
611 /* TTY layer expects 0 on success */
612 return 0;
613
614 err_free_chan:
615 sl->tty = NULL;
616 tty->disc_data = NULL;
617 clear_bit(SLF_INUSE, &sl->flags);
618
619 err_exit:
620 rtnl_unlock();
621
622 /* Count references from TTY module */
623 return err;
624 }
625
626 /*
627 * Close down a SLCAN channel.
628 * This means flushing out any pending queues, and then returning. This
629 * call is serialized against other ldisc functions.
630 *
631 * We also use this method for a hangup event.
632 */
633
slcan_close(struct tty_struct * tty)634 static void slcan_close(struct tty_struct *tty)
635 {
636 struct slcan *sl = (struct slcan *) tty->disc_data;
637
638 /* First make sure we're connected. */
639 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
640 return;
641
642 spin_lock_bh(&sl->lock);
643 tty->disc_data = NULL;
644 sl->tty = NULL;
645 spin_unlock_bh(&sl->lock);
646
647 flush_work(&sl->tx_work);
648
649 /* Flush network side */
650 unregister_netdev(sl->dev);
651 /* This will complete via sl_free_netdev */
652 }
653
slcan_hangup(struct tty_struct * tty)654 static int slcan_hangup(struct tty_struct *tty)
655 {
656 slcan_close(tty);
657 return 0;
658 }
659
660 /* Perform I/O control on an active SLCAN channel. */
slcan_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)661 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
662 unsigned int cmd, unsigned long arg)
663 {
664 struct slcan *sl = (struct slcan *) tty->disc_data;
665 unsigned int tmp;
666
667 /* First make sure we're connected. */
668 if (!sl || sl->magic != SLCAN_MAGIC)
669 return -EINVAL;
670
671 switch (cmd) {
672 case SIOCGIFNAME:
673 tmp = strlen(sl->dev->name) + 1;
674 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
675 return -EFAULT;
676 return 0;
677
678 case SIOCSIFHWADDR:
679 return -EINVAL;
680
681 default:
682 return tty_mode_ioctl(tty, file, cmd, arg);
683 }
684 }
685
686 static struct tty_ldisc_ops slc_ldisc = {
687 .owner = THIS_MODULE,
688 .magic = TTY_LDISC_MAGIC,
689 .name = "slcan",
690 .open = slcan_open,
691 .close = slcan_close,
692 .hangup = slcan_hangup,
693 .ioctl = slcan_ioctl,
694 .receive_buf = slcan_receive_buf,
695 .write_wakeup = slcan_write_wakeup,
696 };
697
slcan_init(void)698 static int __init slcan_init(void)
699 {
700 int status;
701
702 if (maxdev < 4)
703 maxdev = 4; /* Sanity */
704
705 printk(banner);
706 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
707
708 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
709 if (!slcan_devs)
710 return -ENOMEM;
711
712 /* Fill in our line protocol discipline, and register it */
713 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
714 if (status) {
715 printk(KERN_ERR "slcan: can't register line discipline\n");
716 kfree(slcan_devs);
717 }
718 return status;
719 }
720
slcan_exit(void)721 static void __exit slcan_exit(void)
722 {
723 int i;
724 struct net_device *dev;
725 struct slcan *sl;
726 unsigned long timeout = jiffies + HZ;
727 int busy = 0;
728
729 if (slcan_devs == NULL)
730 return;
731
732 /* First of all: check for active disciplines and hangup them.
733 */
734 do {
735 if (busy)
736 msleep_interruptible(100);
737
738 busy = 0;
739 for (i = 0; i < maxdev; i++) {
740 dev = slcan_devs[i];
741 if (!dev)
742 continue;
743 sl = netdev_priv(dev);
744 spin_lock_bh(&sl->lock);
745 if (sl->tty) {
746 busy++;
747 tty_hangup(sl->tty);
748 }
749 spin_unlock_bh(&sl->lock);
750 }
751 } while (busy && time_before(jiffies, timeout));
752
753 /* FIXME: hangup is async so we should wait when doing this second
754 phase */
755
756 for (i = 0; i < maxdev; i++) {
757 dev = slcan_devs[i];
758 if (!dev)
759 continue;
760 slcan_devs[i] = NULL;
761
762 sl = netdev_priv(dev);
763 if (sl->tty) {
764 printk(KERN_ERR "%s: tty discipline still running\n",
765 dev->name);
766 /* Intentionally leak the control block. */
767 dev->destructor = NULL;
768 }
769
770 unregister_netdev(dev);
771 }
772
773 kfree(slcan_devs);
774 slcan_devs = NULL;
775
776 i = tty_unregister_ldisc(N_SLCAN);
777 if (i)
778 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
779 }
780
781 module_init(slcan_init);
782 module_exit(slcan_exit);
783