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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/can.h>
56#include <linux/can/skb.h>
57
58static __initconst const char banner[] =
59 KERN_INFO "slcan: serial line CAN interface driver\n";
60
61MODULE_ALIAS_LDISC(N_SLCAN);
62MODULE_DESCRIPTION("serial line CAN interface");
63MODULE_LICENSE("GPL");
64MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
65
66#define SLCAN_MAGIC 0x53CA
67
68static int maxdev = 10; /* MAX number of SLCAN channels;
69 This can be overridden with
70 insmod slcan.ko maxdev=nnn */
71module_param(maxdev, int, 0);
72MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
73
74/* maximum rx buffer len: extended CAN frame with timestamp */
75#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
76
77#define SLC_CMD_LEN 1
78#define SLC_SFF_ID_LEN 3
79#define SLC_EFF_ID_LEN 8
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, tmp;
148 u32 tmpid;
149 char *cmd = sl->rbuff;
150
151 cf.can_id = 0;
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 *(u64 *) (&cf.data) = 0; /* clear payload */
191
192 /* RTR frames may have a dlc > 0 but they never have any data bytes */
193 if (!(cf.can_id & CAN_RTR_FLAG)) {
194 for (i = 0; i < cf.can_dlc; i++) {
195 tmp = hex_to_bin(*cmd++);
196 if (tmp < 0)
197 return;
198 cf.data[i] = (tmp << 4);
199 tmp = hex_to_bin(*cmd++);
200 if (tmp < 0)
201 return;
202 cf.data[i] |= tmp;
203 }
204 }
205
206 skb = dev_alloc_skb(sizeof(struct can_frame) +
207 sizeof(struct can_skb_priv));
208 if (!skb)
209 return;
210
211 skb->dev = sl->dev;
212 skb->protocol = htons(ETH_P_CAN);
213 skb->pkt_type = PACKET_BROADCAST;
214 skb->ip_summed = CHECKSUM_UNNECESSARY;
215
216 can_skb_reserve(skb);
217 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
218
219 memcpy(skb_put(skb, sizeof(struct can_frame)),
220 &cf, sizeof(struct can_frame));
221 netif_rx_ni(skb);
222
223 sl->dev->stats.rx_packets++;
224 sl->dev->stats.rx_bytes += cf.can_dlc;
225}
226
227/* parse tty input stream */
228static void slcan_unesc(struct slcan *sl, unsigned char s)
229{
230 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
231 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
232 (sl->rcount > 4)) {
233 slc_bump(sl);
234 }
235 sl->rcount = 0;
236 } else {
237 if (!test_bit(SLF_ERROR, &sl->flags)) {
238 if (sl->rcount < SLC_MTU) {
239 sl->rbuff[sl->rcount++] = s;
240 return;
241 } else {
242 sl->dev->stats.rx_over_errors++;
243 set_bit(SLF_ERROR, &sl->flags);
244 }
245 }
246 }
247}
248
249 /************************************************************************
250 * STANDARD SLCAN ENCAPSULATION *
251 ************************************************************************/
252
253/* Encapsulate one can_frame and stuff into a TTY queue. */
254static void slc_encaps(struct slcan *sl, struct can_frame *cf)
255{
256 int actual, i;
257 unsigned char *pos;
258 unsigned char *endpos;
259 canid_t id = cf->can_id;
260
261 pos = sl->xbuff;
262
263 if (cf->can_id & CAN_RTR_FLAG)
264 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
265 else
266 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
267
268 /* determine number of chars for the CAN-identifier */
269 if (cf->can_id & CAN_EFF_FLAG) {
270 id &= CAN_EFF_MASK;
271 endpos = pos + SLC_EFF_ID_LEN;
272 } else {
273 *pos |= 0x20; /* convert R/T to lower case for SFF */
274 id &= CAN_SFF_MASK;
275 endpos = pos + SLC_SFF_ID_LEN;
276 }
277
278 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
279 pos++;
280 while (endpos >= pos) {
281 *endpos-- = hex_asc_upper[id & 0xf];
282 id >>= 4;
283 }
284
285 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
286
287 *pos++ = cf->can_dlc + '0';
288
289 /* RTR frames may have a dlc > 0 but they never have any data bytes */
290 if (!(cf->can_id & CAN_RTR_FLAG)) {
291 for (i = 0; i < cf->can_dlc; i++)
292 pos = hex_byte_pack_upper(pos, cf->data[i]);
293 }
294
295 *pos++ = '\r';
296
297 /* Order of next two lines is *very* important.
298 * When we are sending a little amount of data,
299 * the transfer may be completed inside the ops->write()
300 * routine, because it's running with interrupts enabled.
301 * In this case we *never* got WRITE_WAKEUP event,
302 * if we did not request it before write operation.
303 * 14 Oct 1994 Dmitry Gorodchanin.
304 */
305 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
306 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
307 sl->xleft = (pos - sl->xbuff) - actual;
308 sl->xhead = sl->xbuff + actual;
309 sl->dev->stats.tx_bytes += cf->can_dlc;
310}
311
312/*
313 * Called by the driver when there's room for more data. If we have
314 * more packets to send, we send them here.
315 */
316static void slcan_write_wakeup(struct tty_struct *tty)
317{
318 int actual;
319 struct slcan *sl = (struct slcan *) tty->disc_data;
320
321 /* First make sure we're connected. */
322 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
323 return;
324
325 spin_lock_bh(&sl->lock);
326 if (sl->xleft <= 0) {
327 /* Now serial buffer is almost free & we can start
328 * transmission of another packet */
329 sl->dev->stats.tx_packets++;
330 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
331 spin_unlock_bh(&sl->lock);
332 netif_wake_queue(sl->dev);
333 return;
334 }
335
336 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
337 sl->xleft -= actual;
338 sl->xhead += actual;
339 spin_unlock_bh(&sl->lock);
340}
341
342/* Send a can_frame to a TTY queue. */
343static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
344{
345 struct slcan *sl = netdev_priv(dev);
346
347 if (skb->len != sizeof(struct can_frame))
348 goto out;
349
350 spin_lock(&sl->lock);
351 if (!netif_running(dev)) {
352 spin_unlock(&sl->lock);
353 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
354 goto out;
355 }
356 if (sl->tty == NULL) {
357 spin_unlock(&sl->lock);
358 goto out;
359 }
360
361 netif_stop_queue(sl->dev);
362 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
363 spin_unlock(&sl->lock);
364
365out:
366 kfree_skb(skb);
367 return NETDEV_TX_OK;
368}
369
370
371/******************************************
372 * Routines looking at netdevice side.
373 ******************************************/
374
375/* Netdevice UP -> DOWN routine */
376static int slc_close(struct net_device *dev)
377{
378 struct slcan *sl = netdev_priv(dev);
379
380 spin_lock_bh(&sl->lock);
381 if (sl->tty) {
382 /* TTY discipline is running. */
383 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
384 }
385 netif_stop_queue(dev);
386 sl->rcount = 0;
387 sl->xleft = 0;
388 spin_unlock_bh(&sl->lock);
389
390 return 0;
391}
392
393/* Netdevice DOWN -> UP routine */
394static int slc_open(struct net_device *dev)
395{
396 struct slcan *sl = netdev_priv(dev);
397
398 if (sl->tty == NULL)
399 return -ENODEV;
400
401 sl->flags &= (1 << SLF_INUSE);
402 netif_start_queue(dev);
403 return 0;
404}
405
406/* Hook the destructor so we can free slcan devs at the right point in time */
407static void slc_free_netdev(struct net_device *dev)
408{
409 int i = dev->base_addr;
410 free_netdev(dev);
411 slcan_devs[i] = NULL;
412}
413
414static int slcan_change_mtu(struct net_device *dev, int new_mtu)
415{
416 return -EINVAL;
417}
418
419static const struct net_device_ops slc_netdev_ops = {
420 .ndo_open = slc_open,
421 .ndo_stop = slc_close,
422 .ndo_start_xmit = slc_xmit,
423 .ndo_change_mtu = slcan_change_mtu,
424};
425
426static void slc_setup(struct net_device *dev)
427{
428 dev->netdev_ops = &slc_netdev_ops;
429 dev->destructor = slc_free_netdev;
430
431 dev->hard_header_len = 0;
432 dev->addr_len = 0;
433 dev->tx_queue_len = 10;
434
435 dev->mtu = sizeof(struct can_frame);
436 dev->type = ARPHRD_CAN;
437
438 /* New-style flags. */
439 dev->flags = IFF_NOARP;
440 dev->features = NETIF_F_HW_CSUM;
441}
442
443/******************************************
444 Routines looking at TTY side.
445 ******************************************/
446
447/*
448 * Handle the 'receiver data ready' interrupt.
449 * This function is called by the 'tty_io' module in the kernel when
450 * a block of SLCAN data has been received, which can now be decapsulated
451 * and sent on to some IP layer for further processing. This will not
452 * be re-entered while running but other ldisc functions may be called
453 * in parallel
454 */
455
456static void slcan_receive_buf(struct tty_struct *tty,
457 const unsigned char *cp, char *fp, int count)
458{
459 struct slcan *sl = (struct slcan *) tty->disc_data;
460
461 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
462 return;
463
464 /* Read the characters out of the buffer */
465 while (count--) {
466 if (fp && *fp++) {
467 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
468 sl->dev->stats.rx_errors++;
469 cp++;
470 continue;
471 }
472 slcan_unesc(sl, *cp++);
473 }
474}
475
476/************************************
477 * slcan_open helper routines.
478 ************************************/
479
480/* Collect hanged up channels */
481static void slc_sync(void)
482{
483 int i;
484 struct net_device *dev;
485 struct slcan *sl;
486
487 for (i = 0; i < maxdev; i++) {
488 dev = slcan_devs[i];
489 if (dev == NULL)
490 break;
491
492 sl = netdev_priv(dev);
493 if (sl->tty)
494 continue;
495 if (dev->flags & IFF_UP)
496 dev_close(dev);
497 }
498}
499
500/* Find a free SLCAN channel, and link in this `tty' line. */
501static struct slcan *slc_alloc(dev_t line)
502{
503 int i;
504 char name[IFNAMSIZ];
505 struct net_device *dev = NULL;
506 struct slcan *sl;
507
508 for (i = 0; i < maxdev; i++) {
509 dev = slcan_devs[i];
510 if (dev == NULL)
511 break;
512
513 }
514
515 /* Sorry, too many, all slots in use */
516 if (i >= maxdev)
517 return NULL;
518
519 sprintf(name, "slcan%d", i);
520 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
521 if (!dev)
522 return NULL;
523
524 dev->base_addr = i;
525 sl = netdev_priv(dev);
526
527 /* Initialize channel control data */
528 sl->magic = SLCAN_MAGIC;
529 sl->dev = dev;
530 spin_lock_init(&sl->lock);
531 slcan_devs[i] = dev;
532
533 return sl;
534}
535
536/*
537 * Open the high-level part of the SLCAN channel.
538 * This function is called by the TTY module when the
539 * SLCAN line discipline is called for. Because we are
540 * sure the tty line exists, we only have to link it to
541 * a free SLCAN channel...
542 *
543 * Called in process context serialized from other ldisc calls.
544 */
545
546static int slcan_open(struct tty_struct *tty)
547{
548 struct slcan *sl;
549 int err;
550
551 if (!capable(CAP_NET_ADMIN))
552 return -EPERM;
553
554 if (tty->ops->write == NULL)
555 return -EOPNOTSUPP;
556
557 /* RTnetlink lock is misused here to serialize concurrent
558 opens of slcan channels. There are better ways, but it is
559 the simplest one.
560 */
561 rtnl_lock();
562
563 /* Collect hanged up channels. */
564 slc_sync();
565
566 sl = tty->disc_data;
567
568 err = -EEXIST;
569 /* First make sure we're not already connected. */
570 if (sl && sl->magic == SLCAN_MAGIC)
571 goto err_exit;
572
573 /* OK. Find a free SLCAN channel to use. */
574 err = -ENFILE;
575 sl = slc_alloc(tty_devnum(tty));
576 if (sl == NULL)
577 goto err_exit;
578
579 sl->tty = tty;
580 tty->disc_data = sl;
581
582 if (!test_bit(SLF_INUSE, &sl->flags)) {
583 /* Perform the low-level SLCAN initialization. */
584 sl->rcount = 0;
585 sl->xleft = 0;
586
587 set_bit(SLF_INUSE, &sl->flags);
588
589 err = register_netdevice(sl->dev);
590 if (err)
591 goto err_free_chan;
592 }
593
594 /* Done. We have linked the TTY line to a channel. */
595 rtnl_unlock();
596 tty->receive_room = 65536; /* We don't flow control */
597
598 /* TTY layer expects 0 on success */
599 return 0;
600
601err_free_chan:
602 sl->tty = NULL;
603 tty->disc_data = NULL;
604 clear_bit(SLF_INUSE, &sl->flags);
605
606err_exit:
607 rtnl_unlock();
608
609 /* Count references from TTY module */
610 return err;
611}
612
613/*
614 * Close down a SLCAN channel.
615 * This means flushing out any pending queues, and then returning. This
616 * call is serialized against other ldisc functions.
617 *
618 * We also use this method for a hangup event.
619 */
620
621static void slcan_close(struct tty_struct *tty)
622{
623 struct slcan *sl = (struct slcan *) tty->disc_data;
624
625 /* First make sure we're connected. */
626 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
627 return;
628
629 tty->disc_data = NULL;
630 sl->tty = NULL;
631
632 /* Flush network side */
633 unregister_netdev(sl->dev);
634 /* This will complete via sl_free_netdev */
635}
636
637static int slcan_hangup(struct tty_struct *tty)
638{
639 slcan_close(tty);
640 return 0;
641}
642
643/* Perform I/O control on an active SLCAN channel. */
644static int slcan_ioctl(struct tty_struct *tty, struct file *file,
645 unsigned int cmd, unsigned long arg)
646{
647 struct slcan *sl = (struct slcan *) tty->disc_data;
648 unsigned int tmp;
649
650 /* First make sure we're connected. */
651 if (!sl || sl->magic != SLCAN_MAGIC)
652 return -EINVAL;
653
654 switch (cmd) {
655 case SIOCGIFNAME:
656 tmp = strlen(sl->dev->name) + 1;
657 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
658 return -EFAULT;
659 return 0;
660
661 case SIOCSIFHWADDR:
662 return -EINVAL;
663
664 default:
665 return tty_mode_ioctl(tty, file, cmd, arg);
666 }
667}
668
669static struct tty_ldisc_ops slc_ldisc = {
670 .owner = THIS_MODULE,
671 .magic = TTY_LDISC_MAGIC,
672 .name = "slcan",
673 .open = slcan_open,
674 .close = slcan_close,
675 .hangup = slcan_hangup,
676 .ioctl = slcan_ioctl,
677 .receive_buf = slcan_receive_buf,
678 .write_wakeup = slcan_write_wakeup,
679};
680
681static int __init slcan_init(void)
682{
683 int status;
684
685 if (maxdev < 4)
686 maxdev = 4; /* Sanity */
687
688 printk(banner);
689 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
690
691 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
692 if (!slcan_devs)
693 return -ENOMEM;
694
695 /* Fill in our line protocol discipline, and register it */
696 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
697 if (status) {
698 printk(KERN_ERR "slcan: can't register line discipline\n");
699 kfree(slcan_devs);
700 }
701 return status;
702}
703
704static void __exit slcan_exit(void)
705{
706 int i;
707 struct net_device *dev;
708 struct slcan *sl;
709 unsigned long timeout = jiffies + HZ;
710 int busy = 0;
711
712 if (slcan_devs == NULL)
713 return;
714
715 /* First of all: check for active disciplines and hangup them.
716 */
717 do {
718 if (busy)
719 msleep_interruptible(100);
720
721 busy = 0;
722 for (i = 0; i < maxdev; i++) {
723 dev = slcan_devs[i];
724 if (!dev)
725 continue;
726 sl = netdev_priv(dev);
727 spin_lock_bh(&sl->lock);
728 if (sl->tty) {
729 busy++;
730 tty_hangup(sl->tty);
731 }
732 spin_unlock_bh(&sl->lock);
733 }
734 } while (busy && time_before(jiffies, timeout));
735
736 /* FIXME: hangup is async so we should wait when doing this second
737 phase */
738
739 for (i = 0; i < maxdev; i++) {
740 dev = slcan_devs[i];
741 if (!dev)
742 continue;
743 slcan_devs[i] = NULL;
744
745 sl = netdev_priv(dev);
746 if (sl->tty) {
747 printk(KERN_ERR "%s: tty discipline still running\n",
748 dev->name);
749 /* Intentionally leak the control block. */
750 dev->destructor = NULL;
751 }
752
753 unregister_netdev(dev);
754 }
755
756 kfree(slcan_devs);
757 slcan_devs = NULL;
758
759 i = tty_unregister_ldisc(N_SLCAN);
760 if (i)
761 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
762}
763
764module_init(slcan_init);
765module_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/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);