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
60 MODULE_ALIAS_LDISC(N_SLCAN);
61 MODULE_DESCRIPTION("serial line CAN interface");
62 MODULE_LICENSE("GPL");
63 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
64
65 #define SLCAN_MAGIC 0x53CA
66
67 static int maxdev = 10; /* MAX number of SLCAN channels;
68 This can be overridden with
69 insmod slcan.ko maxdev=nnn */
70 module_param(maxdev, int, 0);
71 MODULE_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
80 struct 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
101 static 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 (len) which can be from 0 to 8
110 * and up to <len> 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, len 0, no data
132 * t4563112233 : can_id 0x456, len 3, data 0x11 0x22 0x33
133 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, len 2, data 0xAA 0x55
134 * r1230 : can_id 0x123, len 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 */
slc_bump(struct slcan * sl)143 static 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.len = 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.len = 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 len from sanitized ASCII value */
185 if (cf.len >= '0' && cf.len < '9')
186 cf.len -= '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.len; 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.len;
222 netif_rx_ni(skb);
223 }
224
225 /* parse tty input stream */
slcan_unesc(struct slcan * sl,unsigned char s)226 static 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. */
slc_encaps(struct slcan * sl,struct can_frame * cf)252 static 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->len + '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->len; 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->len;
308 }
309
310 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
slcan_transmit(struct work_struct * work)311 static 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 */
slcan_write_wakeup(struct tty_struct * tty)343 static 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. */
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 != 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
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
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->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
slcan_receive_buf(struct tty_struct * tty,const unsigned char * cp,char * fp,int count)469 static 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 */
slc_sync(void)494 static 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. */
slc_alloc(void)514 static struct slcan *slc_alloc(void)
515 {
516 int i;
517 char name[IFNAMSIZ];
518 struct net_device *dev = NULL;
519 struct can_ml_priv *can_ml;
520 struct slcan *sl;
521 int size;
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 size = ALIGN(sizeof(*sl), NETDEV_ALIGN) + sizeof(struct can_ml_priv);
536 dev = alloc_netdev(size, name, NET_NAME_UNKNOWN, slc_setup);
537 if (!dev)
538 return NULL;
539
540 dev->base_addr = i;
541 sl = netdev_priv(dev);
542 can_ml = (void *)sl + ALIGN(sizeof(*sl), NETDEV_ALIGN);
543 can_set_ml_priv(dev, can_ml);
544
545 /* Initialize channel control data */
546 sl->magic = SLCAN_MAGIC;
547 sl->dev = dev;
548 spin_lock_init(&sl->lock);
549 INIT_WORK(&sl->tx_work, slcan_transmit);
550 slcan_devs[i] = dev;
551
552 return sl;
553 }
554
555 /*
556 * Open the high-level part of the SLCAN channel.
557 * This function is called by the TTY module when the
558 * SLCAN line discipline is called for. Because we are
559 * sure the tty line exists, we only have to link it to
560 * a free SLCAN channel...
561 *
562 * Called in process context serialized from other ldisc calls.
563 */
564
slcan_open(struct tty_struct * tty)565 static int slcan_open(struct tty_struct *tty)
566 {
567 struct slcan *sl;
568 int err;
569
570 if (!capable(CAP_NET_ADMIN))
571 return -EPERM;
572
573 if (tty->ops->write == NULL)
574 return -EOPNOTSUPP;
575
576 /* RTnetlink lock is misused here to serialize concurrent
577 opens of slcan channels. There are better ways, but it is
578 the simplest one.
579 */
580 rtnl_lock();
581
582 /* Collect hanged up channels. */
583 slc_sync();
584
585 sl = tty->disc_data;
586
587 err = -EEXIST;
588 /* First make sure we're not already connected. */
589 if (sl && sl->magic == SLCAN_MAGIC)
590 goto err_exit;
591
592 /* OK. Find a free SLCAN channel to use. */
593 err = -ENFILE;
594 sl = slc_alloc();
595 if (sl == NULL)
596 goto err_exit;
597
598 sl->tty = tty;
599 tty->disc_data = sl;
600
601 if (!test_bit(SLF_INUSE, &sl->flags)) {
602 /* Perform the low-level SLCAN initialization. */
603 sl->rcount = 0;
604 sl->xleft = 0;
605
606 set_bit(SLF_INUSE, &sl->flags);
607
608 err = register_netdevice(sl->dev);
609 if (err)
610 goto err_free_chan;
611 }
612
613 /* Done. We have linked the TTY line to a channel. */
614 rtnl_unlock();
615 tty->receive_room = 65536; /* We don't flow control */
616
617 /* TTY layer expects 0 on success */
618 return 0;
619
620 err_free_chan:
621 sl->tty = NULL;
622 tty->disc_data = NULL;
623 clear_bit(SLF_INUSE, &sl->flags);
624 slc_free_netdev(sl->dev);
625 /* do not call free_netdev before rtnl_unlock */
626 rtnl_unlock();
627 free_netdev(sl->dev);
628 return err;
629
630 err_exit:
631 rtnl_unlock();
632
633 /* Count references from TTY module */
634 return err;
635 }
636
637 /*
638 * Close down a SLCAN channel.
639 * This means flushing out any pending queues, and then returning. This
640 * call is serialized against other ldisc functions.
641 *
642 * We also use this method for a hangup event.
643 */
644
slcan_close(struct tty_struct * tty)645 static void slcan_close(struct tty_struct *tty)
646 {
647 struct slcan *sl = (struct slcan *) tty->disc_data;
648
649 /* First make sure we're connected. */
650 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
651 return;
652
653 spin_lock_bh(&sl->lock);
654 rcu_assign_pointer(tty->disc_data, NULL);
655 sl->tty = NULL;
656 spin_unlock_bh(&sl->lock);
657
658 synchronize_rcu();
659 flush_work(&sl->tx_work);
660
661 /* Flush network side */
662 unregister_netdev(sl->dev);
663 /* This will complete via sl_free_netdev */
664 }
665
slcan_hangup(struct tty_struct * tty)666 static int slcan_hangup(struct tty_struct *tty)
667 {
668 slcan_close(tty);
669 return 0;
670 }
671
672 /* Perform I/O control on an active SLCAN channel. */
slcan_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)673 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
674 unsigned int cmd, unsigned long arg)
675 {
676 struct slcan *sl = (struct slcan *) tty->disc_data;
677 unsigned int tmp;
678
679 /* First make sure we're connected. */
680 if (!sl || sl->magic != SLCAN_MAGIC)
681 return -EINVAL;
682
683 switch (cmd) {
684 case SIOCGIFNAME:
685 tmp = strlen(sl->dev->name) + 1;
686 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
687 return -EFAULT;
688 return 0;
689
690 case SIOCSIFHWADDR:
691 return -EINVAL;
692
693 default:
694 return tty_mode_ioctl(tty, file, cmd, arg);
695 }
696 }
697
698 static struct tty_ldisc_ops slc_ldisc = {
699 .owner = THIS_MODULE,
700 .name = "slcan",
701 .open = slcan_open,
702 .close = slcan_close,
703 .hangup = slcan_hangup,
704 .ioctl = slcan_ioctl,
705 .receive_buf = slcan_receive_buf,
706 .write_wakeup = slcan_write_wakeup,
707 };
708
slcan_init(void)709 static int __init slcan_init(void)
710 {
711 int status;
712
713 if (maxdev < 4)
714 maxdev = 4; /* Sanity */
715
716 pr_info("slcan: serial line CAN interface driver\n");
717 pr_info("slcan: %d dynamic interface channels.\n", maxdev);
718
719 slcan_devs = kcalloc(maxdev, sizeof(struct net_device *), GFP_KERNEL);
720 if (!slcan_devs)
721 return -ENOMEM;
722
723 /* Fill in our line protocol discipline, and register it */
724 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
725 if (status) {
726 printk(KERN_ERR "slcan: can't register line discipline\n");
727 kfree(slcan_devs);
728 }
729 return status;
730 }
731
slcan_exit(void)732 static void __exit slcan_exit(void)
733 {
734 int i;
735 struct net_device *dev;
736 struct slcan *sl;
737 unsigned long timeout = jiffies + HZ;
738 int busy = 0;
739
740 if (slcan_devs == NULL)
741 return;
742
743 /* First of all: check for active disciplines and hangup them.
744 */
745 do {
746 if (busy)
747 msleep_interruptible(100);
748
749 busy = 0;
750 for (i = 0; i < maxdev; i++) {
751 dev = slcan_devs[i];
752 if (!dev)
753 continue;
754 sl = netdev_priv(dev);
755 spin_lock_bh(&sl->lock);
756 if (sl->tty) {
757 busy++;
758 tty_hangup(sl->tty);
759 }
760 spin_unlock_bh(&sl->lock);
761 }
762 } while (busy && time_before(jiffies, timeout));
763
764 /* FIXME: hangup is async so we should wait when doing this second
765 phase */
766
767 for (i = 0; i < maxdev; i++) {
768 dev = slcan_devs[i];
769 if (!dev)
770 continue;
771 slcan_devs[i] = NULL;
772
773 sl = netdev_priv(dev);
774 if (sl->tty) {
775 printk(KERN_ERR "%s: tty discipline still running\n",
776 dev->name);
777 }
778
779 unregister_netdev(dev);
780 }
781
782 kfree(slcan_devs);
783 slcan_devs = NULL;
784
785 i = tty_unregister_ldisc(N_SLCAN);
786 if (i)
787 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
788 }
789
790 module_init(slcan_init);
791 module_exit(slcan_exit);
792