slcan.c revision 9ffc93f203c18a70623f21950f1dd473c9ec48cd 
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, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it
23 * at http://www.gnu.org/licenses/gpl.html
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
36 * DAMAGE.
37 *
38 */
39
40#include <linux/module.h>
41#include <linux/moduleparam.h>
42
43#include <linux/uaccess.h>
44#include <linux/bitops.h>
45#include <linux/string.h>
46#include <linux/tty.h>
47#include <linux/errno.h>
48#include <linux/netdevice.h>
49#include <linux/skbuff.h>
50#include <linux/rtnetlink.h>
51#include <linux/if_arp.h>
52#include <linux/if_ether.h>
53#include <linux/sched.h>
54#include <linux/delay.h>
55#include <linux/init.h>
56#include <linux/kernel.h>
57#include <linux/can.h>
58
59static __initdata const char banner[] =
60	KERN_INFO "slcan: serial line CAN interface driver\n";
61
62MODULE_ALIAS_LDISC(N_SLCAN);
63MODULE_DESCRIPTION("serial line CAN interface");
64MODULE_LICENSE("GPL");
65MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
66
67#define SLCAN_MAGIC 0x53CA
68
69static int maxdev = 10;		/* MAX number of SLCAN channels;
70				   This can be overridden with
71				   insmod slcan.ko maxdev=nnn	*/
72module_param(maxdev, int, 0);
73MODULE_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
78struct slcan {
79	int			magic;
80
81	/* Various fields. */
82	struct tty_struct	*tty;		/* ptr to TTY structure	     */
83	struct net_device	*dev;		/* easy for intr handling    */
84	spinlock_t		lock;
85
86	/* These are pointers to the malloc()ed frame buffers. */
87	unsigned char		rbuff[SLC_MTU];	/* receiver buffer	     */
88	int			rcount;         /* received chars counter    */
89	unsigned char		xbuff[SLC_MTU];	/* transmitter buffer	     */
90	unsigned char		*xhead;         /* pointer to next XMIT byte */
91	int			xleft;          /* bytes left in XMIT queue  */
92
93	unsigned long		flags;		/* Flag values/ mode etc     */
94#define SLF_INUSE		0		/* Channel in use            */
95#define SLF_ERROR		1               /* Parity, etc. error        */
96};
97
98static struct net_device **slcan_devs;
99
100 /************************************************************************
101  *			SLCAN ENCAPSULATION FORMAT			 *
102  ************************************************************************/
103
104/*
105 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
106 * frame format) a data length code (can_dlc) which can be from 0 to 8
107 * and up to <can_dlc> data bytes as payload.
108 * Additionally a CAN frame may become a remote transmission frame if the
109 * RTR-bit is set. This causes another ECU to send a CAN frame with the
110 * given can_id.
111 *
112 * The SLCAN ASCII representation of these different frame types is:
113 * <type> <id> <dlc> <data>*
114 *
115 * Extended frames (29 bit) are defined by capital characters in the type.
116 * RTR frames are defined as 'r' types - normal frames have 't' type:
117 * t => 11 bit data frame
118 * r => 11 bit RTR frame
119 * T => 29 bit data frame
120 * R => 29 bit RTR frame
121 *
122 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
123 * The <dlc> is a one byte ASCII number ('0' - '8')
124 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
125 *
126 * Examples:
127 *
128 * t1230 : can_id 0x123, can_dlc 0, no data
129 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
130 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
131 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
132 *
133 */
134
135 /************************************************************************
136  *			STANDARD SLCAN DECAPSULATION			 *
137  ************************************************************************/
138
139/* Send one completely decapsulated can_frame to the network layer */
140static void slc_bump(struct slcan *sl)
141{
142	struct sk_buff *skb;
143	struct can_frame cf;
144	int i, dlc_pos, tmp;
145	unsigned long ultmp;
146	char cmd = sl->rbuff[0];
147
148	if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
149		return;
150
151	if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
152		dlc_pos = 4; /* dlc position tiiid */
153	else
154		dlc_pos = 9; /* dlc position Tiiiiiiiid */
155
156	if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
157		return;
158
159	cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
160
161	sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
162
163	if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
164		return;
165
166	cf.can_id = ultmp;
167
168	if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
169		cf.can_id |= CAN_EFF_FLAG;
170
171	if ((cmd | 0x20) == 'r') /* RTR frame */
172		cf.can_id |= CAN_RTR_FLAG;
173
174	*(u64 *) (&cf.data) = 0; /* clear payload */
175
176	for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
177		tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
178		if (tmp < 0)
179			return;
180		cf.data[i] = (tmp << 4);
181		tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
182		if (tmp < 0)
183			return;
184		cf.data[i] |= tmp;
185	}
186
187	skb = dev_alloc_skb(sizeof(struct can_frame));
188	if (!skb)
189		return;
190
191	skb->dev = sl->dev;
192	skb->protocol = htons(ETH_P_CAN);
193	skb->pkt_type = PACKET_BROADCAST;
194	skb->ip_summed = CHECKSUM_UNNECESSARY;
195	memcpy(skb_put(skb, sizeof(struct can_frame)),
196	       &cf, sizeof(struct can_frame));
197	netif_rx_ni(skb);
198
199	sl->dev->stats.rx_packets++;
200	sl->dev->stats.rx_bytes += cf.can_dlc;
201}
202
203/* parse tty input stream */
204static void slcan_unesc(struct slcan *sl, unsigned char s)
205{
206
207	if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
208		if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
209		    (sl->rcount > 4))  {
210			slc_bump(sl);
211		}
212		sl->rcount = 0;
213	} else {
214		if (!test_bit(SLF_ERROR, &sl->flags))  {
215			if (sl->rcount < SLC_MTU)  {
216				sl->rbuff[sl->rcount++] = s;
217				return;
218			} else {
219				sl->dev->stats.rx_over_errors++;
220				set_bit(SLF_ERROR, &sl->flags);
221			}
222		}
223	}
224}
225
226 /************************************************************************
227  *			STANDARD SLCAN ENCAPSULATION			 *
228  ************************************************************************/
229
230/* Encapsulate one can_frame and stuff into a TTY queue. */
231static void slc_encaps(struct slcan *sl, struct can_frame *cf)
232{
233	int actual, idx, i;
234	char cmd;
235
236	if (cf->can_id & CAN_RTR_FLAG)
237		cmd = 'R'; /* becomes 'r' in standard frame format */
238	else
239		cmd = 'T'; /* becomes 't' in standard frame format */
240
241	if (cf->can_id & CAN_EFF_FLAG)
242		sprintf(sl->xbuff, "%c%08X%d", cmd,
243			cf->can_id & CAN_EFF_MASK, cf->can_dlc);
244	else
245		sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
246			cf->can_id & CAN_SFF_MASK, cf->can_dlc);
247
248	idx = strlen(sl->xbuff);
249
250	for (i = 0; i < cf->can_dlc; i++)
251		sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
252
253	strcat(sl->xbuff, "\r"); /* add terminating character */
254
255	/* Order of next two lines is *very* important.
256	 * When we are sending a little amount of data,
257	 * the transfer may be completed inside the ops->write()
258	 * routine, because it's running with interrupts enabled.
259	 * In this case we *never* got WRITE_WAKEUP event,
260	 * if we did not request it before write operation.
261	 *       14 Oct 1994  Dmitry Gorodchanin.
262	 */
263	set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
264	actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
265	sl->xleft = strlen(sl->xbuff) - actual;
266	sl->xhead = sl->xbuff + actual;
267	sl->dev->stats.tx_bytes += cf->can_dlc;
268}
269
270/*
271 * Called by the driver when there's room for more data.  If we have
272 * more packets to send, we send them here.
273 */
274static void slcan_write_wakeup(struct tty_struct *tty)
275{
276	int actual;
277	struct slcan *sl = (struct slcan *) tty->disc_data;
278
279	/* First make sure we're connected. */
280	if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
281		return;
282
283	if (sl->xleft <= 0)  {
284		/* Now serial buffer is almost free & we can start
285		 * transmission of another packet */
286		sl->dev->stats.tx_packets++;
287		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
288		netif_wake_queue(sl->dev);
289		return;
290	}
291
292	actual = tty->ops->write(tty, sl->xhead, sl->xleft);
293	sl->xleft -= actual;
294	sl->xhead += actual;
295}
296
297/* Send a can_frame to a TTY queue. */
298static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
299{
300	struct slcan *sl = netdev_priv(dev);
301
302	if (skb->len != sizeof(struct can_frame))
303		goto out;
304
305	spin_lock(&sl->lock);
306	if (!netif_running(dev))  {
307		spin_unlock(&sl->lock);
308		printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
309		goto out;
310	}
311	if (sl->tty == NULL) {
312		spin_unlock(&sl->lock);
313		goto out;
314	}
315
316	netif_stop_queue(sl->dev);
317	slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
318	spin_unlock(&sl->lock);
319
320out:
321	kfree_skb(skb);
322	return NETDEV_TX_OK;
323}
324
325
326/******************************************
327 *   Routines looking at netdevice side.
328 ******************************************/
329
330/* Netdevice UP -> DOWN routine */
331static int slc_close(struct net_device *dev)
332{
333	struct slcan *sl = netdev_priv(dev);
334
335	spin_lock_bh(&sl->lock);
336	if (sl->tty) {
337		/* TTY discipline is running. */
338		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
339	}
340	netif_stop_queue(dev);
341	sl->rcount   = 0;
342	sl->xleft    = 0;
343	spin_unlock_bh(&sl->lock);
344
345	return 0;
346}
347
348/* Netdevice DOWN -> UP routine */
349static int slc_open(struct net_device *dev)
350{
351	struct slcan *sl = netdev_priv(dev);
352
353	if (sl->tty == NULL)
354		return -ENODEV;
355
356	sl->flags &= (1 << SLF_INUSE);
357	netif_start_queue(dev);
358	return 0;
359}
360
361/* Hook the destructor so we can free slcan devs at the right point in time */
362static void slc_free_netdev(struct net_device *dev)
363{
364	int i = dev->base_addr;
365	free_netdev(dev);
366	slcan_devs[i] = NULL;
367}
368
369static const struct net_device_ops slc_netdev_ops = {
370	.ndo_open               = slc_open,
371	.ndo_stop               = slc_close,
372	.ndo_start_xmit         = slc_xmit,
373};
374
375static void slc_setup(struct net_device *dev)
376{
377	dev->netdev_ops		= &slc_netdev_ops;
378	dev->destructor		= slc_free_netdev;
379
380	dev->hard_header_len	= 0;
381	dev->addr_len		= 0;
382	dev->tx_queue_len	= 10;
383
384	dev->mtu		= sizeof(struct can_frame);
385	dev->type		= ARPHRD_CAN;
386
387	/* New-style flags. */
388	dev->flags		= IFF_NOARP;
389	dev->features           = NETIF_F_HW_CSUM;
390}
391
392/******************************************
393  Routines looking at TTY side.
394 ******************************************/
395
396/*
397 * Handle the 'receiver data ready' interrupt.
398 * This function is called by the 'tty_io' module in the kernel when
399 * a block of SLCAN data has been received, which can now be decapsulated
400 * and sent on to some IP layer for further processing. This will not
401 * be re-entered while running but other ldisc functions may be called
402 * in parallel
403 */
404
405static void slcan_receive_buf(struct tty_struct *tty,
406			      const unsigned char *cp, char *fp, int count)
407{
408	struct slcan *sl = (struct slcan *) tty->disc_data;
409
410	if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
411		return;
412
413	/* Read the characters out of the buffer */
414	while (count--) {
415		if (fp && *fp++) {
416			if (!test_and_set_bit(SLF_ERROR, &sl->flags))
417				sl->dev->stats.rx_errors++;
418			cp++;
419			continue;
420		}
421		slcan_unesc(sl, *cp++);
422	}
423}
424
425/************************************
426 *  slcan_open helper routines.
427 ************************************/
428
429/* Collect hanged up channels */
430static void slc_sync(void)
431{
432	int i;
433	struct net_device *dev;
434	struct slcan	  *sl;
435
436	for (i = 0; i < maxdev; i++) {
437		dev = slcan_devs[i];
438		if (dev == NULL)
439			break;
440
441		sl = netdev_priv(dev);
442		if (sl->tty)
443			continue;
444		if (dev->flags & IFF_UP)
445			dev_close(dev);
446	}
447}
448
449/* Find a free SLCAN channel, and link in this `tty' line. */
450static struct slcan *slc_alloc(dev_t line)
451{
452	int i;
453	char name[IFNAMSIZ];
454	struct net_device *dev = NULL;
455	struct slcan       *sl;
456
457	for (i = 0; i < maxdev; i++) {
458		dev = slcan_devs[i];
459		if (dev == NULL)
460			break;
461
462	}
463
464	/* Sorry, too many, all slots in use */
465	if (i >= maxdev)
466		return NULL;
467
468	sprintf(name, "slcan%d", i);
469	dev = alloc_netdev(sizeof(*sl), name, slc_setup);
470	if (!dev)
471		return NULL;
472
473	dev->base_addr  = i;
474	sl = netdev_priv(dev);
475
476	/* Initialize channel control data */
477	sl->magic = SLCAN_MAGIC;
478	sl->dev	= dev;
479	spin_lock_init(&sl->lock);
480	slcan_devs[i] = dev;
481
482	return sl;
483}
484
485/*
486 * Open the high-level part of the SLCAN channel.
487 * This function is called by the TTY module when the
488 * SLCAN line discipline is called for.  Because we are
489 * sure the tty line exists, we only have to link it to
490 * a free SLCAN channel...
491 *
492 * Called in process context serialized from other ldisc calls.
493 */
494
495static int slcan_open(struct tty_struct *tty)
496{
497	struct slcan *sl;
498	int err;
499
500	if (!capable(CAP_NET_ADMIN))
501		return -EPERM;
502
503	if (tty->ops->write == NULL)
504		return -EOPNOTSUPP;
505
506	/* RTnetlink lock is misused here to serialize concurrent
507	   opens of slcan channels. There are better ways, but it is
508	   the simplest one.
509	 */
510	rtnl_lock();
511
512	/* Collect hanged up channels. */
513	slc_sync();
514
515	sl = tty->disc_data;
516
517	err = -EEXIST;
518	/* First make sure we're not already connected. */
519	if (sl && sl->magic == SLCAN_MAGIC)
520		goto err_exit;
521
522	/* OK.  Find a free SLCAN channel to use. */
523	err = -ENFILE;
524	sl = slc_alloc(tty_devnum(tty));
525	if (sl == NULL)
526		goto err_exit;
527
528	sl->tty = tty;
529	tty->disc_data = sl;
530
531	if (!test_bit(SLF_INUSE, &sl->flags)) {
532		/* Perform the low-level SLCAN initialization. */
533		sl->rcount   = 0;
534		sl->xleft    = 0;
535
536		set_bit(SLF_INUSE, &sl->flags);
537
538		err = register_netdevice(sl->dev);
539		if (err)
540			goto err_free_chan;
541	}
542
543	/* Done.  We have linked the TTY line to a channel. */
544	rtnl_unlock();
545	tty->receive_room = 65536;	/* We don't flow control */
546
547	/* TTY layer expects 0 on success */
548	return 0;
549
550err_free_chan:
551	sl->tty = NULL;
552	tty->disc_data = NULL;
553	clear_bit(SLF_INUSE, &sl->flags);
554
555err_exit:
556	rtnl_unlock();
557
558	/* Count references from TTY module */
559	return err;
560}
561
562/*
563 * Close down a SLCAN channel.
564 * This means flushing out any pending queues, and then returning. This
565 * call is serialized against other ldisc functions.
566 *
567 * We also use this method for a hangup event.
568 */
569
570static void slcan_close(struct tty_struct *tty)
571{
572	struct slcan *sl = (struct slcan *) tty->disc_data;
573
574	/* First make sure we're connected. */
575	if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
576		return;
577
578	tty->disc_data = NULL;
579	sl->tty = NULL;
580
581	/* Flush network side */
582	unregister_netdev(sl->dev);
583	/* This will complete via sl_free_netdev */
584}
585
586static int slcan_hangup(struct tty_struct *tty)
587{
588	slcan_close(tty);
589	return 0;
590}
591
592/* Perform I/O control on an active SLCAN channel. */
593static int slcan_ioctl(struct tty_struct *tty, struct file *file,
594		       unsigned int cmd, unsigned long arg)
595{
596	struct slcan *sl = (struct slcan *) tty->disc_data;
597	unsigned int tmp;
598
599	/* First make sure we're connected. */
600	if (!sl || sl->magic != SLCAN_MAGIC)
601		return -EINVAL;
602
603	switch (cmd) {
604	case SIOCGIFNAME:
605		tmp = strlen(sl->dev->name) + 1;
606		if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
607			return -EFAULT;
608		return 0;
609
610	case SIOCSIFHWADDR:
611		return -EINVAL;
612
613	default:
614		return tty_mode_ioctl(tty, file, cmd, arg);
615	}
616}
617
618static struct tty_ldisc_ops slc_ldisc = {
619	.owner		= THIS_MODULE,
620	.magic		= TTY_LDISC_MAGIC,
621	.name		= "slcan",
622	.open		= slcan_open,
623	.close		= slcan_close,
624	.hangup		= slcan_hangup,
625	.ioctl		= slcan_ioctl,
626	.receive_buf	= slcan_receive_buf,
627	.write_wakeup	= slcan_write_wakeup,
628};
629
630static int __init slcan_init(void)
631{
632	int status;
633
634	if (maxdev < 4)
635		maxdev = 4; /* Sanity */
636
637	printk(banner);
638	printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
639
640	slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
641	if (!slcan_devs)
642		return -ENOMEM;
643
644	/* Fill in our line protocol discipline, and register it */
645	status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
646	if (status)  {
647		printk(KERN_ERR "slcan: can't register line discipline\n");
648		kfree(slcan_devs);
649	}
650	return status;
651}
652
653static void __exit slcan_exit(void)
654{
655	int i;
656	struct net_device *dev;
657	struct slcan *sl;
658	unsigned long timeout = jiffies + HZ;
659	int busy = 0;
660
661	if (slcan_devs == NULL)
662		return;
663
664	/* First of all: check for active disciplines and hangup them.
665	 */
666	do {
667		if (busy)
668			msleep_interruptible(100);
669
670		busy = 0;
671		for (i = 0; i < maxdev; i++) {
672			dev = slcan_devs[i];
673			if (!dev)
674				continue;
675			sl = netdev_priv(dev);
676			spin_lock_bh(&sl->lock);
677			if (sl->tty) {
678				busy++;
679				tty_hangup(sl->tty);
680			}
681			spin_unlock_bh(&sl->lock);
682		}
683	} while (busy && time_before(jiffies, timeout));
684
685	/* FIXME: hangup is async so we should wait when doing this second
686	   phase */
687
688	for (i = 0; i < maxdev; i++) {
689		dev = slcan_devs[i];
690		if (!dev)
691			continue;
692		slcan_devs[i] = NULL;
693
694		sl = netdev_priv(dev);
695		if (sl->tty) {
696			printk(KERN_ERR "%s: tty discipline still running\n",
697			       dev->name);
698			/* Intentionally leak the control block. */
699			dev->destructor = NULL;
700		}
701
702		unregister_netdev(dev);
703	}
704
705	kfree(slcan_devs);
706	slcan_devs = NULL;
707
708	i = tty_unregister_ldisc(N_SLCAN);
709	if (i)
710		printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
711}
712
713module_init(slcan_init);
714module_exit(slcan_exit);
715