2 * slcan.c - serial line CAN interface driver (using tty line discipline)
4 * Copyright (c) 2007 Volkswagen Group Electronic Research
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of Volkswagen nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * Alternatively, provided that this notice is retained in full, this
20 * software may be distributed under the terms of the GNU General
21 * Public License ("GPL") version 2, in which case the provisions of the
22 * GPL apply INSTEAD OF those given above.
24 * The provided data structures and external interfaces from this code
25 * are not restricted to be used by modules with a GPL compatible license.
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
30 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
32 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
33 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
40 * Send feedback to <socketcan-users@lists.berlios.de>
45 * This file is derived from linux/drivers/net/slip.c
47 * Therefore it has the same (strange?) behaviour not to unregister the
48 * netdevice when detaching the tty. Is there any better solution?
50 * Do not try to attach, detach and re-attach a tty for this reason ...
52 * slip.c Authors: Laurence Culhane, <loz@holmes.demon.co.uk>
53 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
56 #include <linux/version.h>
57 #include <linux/module.h>
58 #include <linux/moduleparam.h>
60 #include <asm/system.h>
61 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,17)
62 #include <linux/uaccess.h>
64 #include <asm/uaccess.h>
66 #include <linux/bitops.h>
67 #include <linux/string.h>
69 #include <linux/interrupt.h>
71 #include <linux/tty.h>
72 #include <linux/errno.h>
73 #include <linux/netdevice.h>
74 #include <linux/etherdevice.h>
75 #include <linux/skbuff.h>
76 #include <linux/rtnetlink.h>
77 #include <linux/if_arp.h>
78 #include <linux/if_ether.h>
79 #include <linux/if_slip.h>
80 #include <linux/delay.h>
81 #include <linux/init.h>
83 #include <linux/can.h>
85 #include <linux/can/version.h> /* for RCSID. Removed by mkpatch script */
88 static __initdata const char banner[] =
89 KERN_INFO "slcan: serial line CAN interface driver\n";
91 MODULE_ALIAS_LDISC(N_SLCAN);
92 MODULE_DESCRIPTION("serial line CAN interface");
93 MODULE_LICENSE("Dual BSD/GPL");
94 MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
96 #ifdef CONFIG_CAN_DEBUG_DEVICES
98 module_param(debug, int, S_IRUGO);
99 #define DBG(args...) (debug & 1 ? \
100 (printk(KERN_DEBUG "slcan %s: ", __func__), \
107 #error Your kernel does not support tty line discipline N_SLCAN
110 * As there is currently no line discipline N_SLCAN in the mainstream kernel
111 * you will have to modify two kernel includes & recompile the kernel.
113 * Add this in include/asm/termios.h after the definition of N_HCI:
116 * Increment NR_LDICS in include/linux/tty.h from 16 to 17
118 * NEW: Since Kernel 2.6.21 you only have to change include/linux/tty.h
122 #define SLC_CHECK_TRANSMIT
123 #define SLCAN_MAGIC 0x53CA
125 static int maxdev = 10; /* MAX number of SLCAN channels;
126 This can be overridden with
127 insmod slcan.ko maxdev=nnn */
128 module_param(maxdev, int, 0);
129 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
131 /* maximum rx buffer len: extended CAN frame with timestamp */
132 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
137 /* Various fields. */
138 struct tty_struct *tty; /* ptr to TTY structure */
139 struct net_device *dev; /* easy for intr handling */
142 /* These are pointers to the malloc()ed frame buffers. */
143 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
144 int rcount; /* received chars counter */
145 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
146 unsigned char *xhead; /* pointer to next XMIT byte */
147 int xleft; /* bytes left in XMIT queue */
149 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
150 /* SLCAN interface statistics. */
151 struct net_device_stats stats;
154 unsigned long flags; /* Flag values/ mode etc */
155 #define SLF_INUSE 0 /* Channel in use */
156 #define SLF_ERROR 1 /* Parity, etc. error */
158 unsigned char leased;
163 static struct net_device **slcan_devs;
165 /************************************************************************
166 * SLCAN ENCAPSULATION FORMAT *
167 ************************************************************************/
170 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
171 * frame format) a data length code (can_dlc) which can be from 0 to 8
172 * and up to <can_dlc> data bytes as payload.
173 * Additionally a CAN frame may become a remote transmission frame if the
174 * RTR-bit is set. This causes another ECU to send a CAN frame with the
177 * The SLCAN ASCII representation of these different frame types is:
178 * <type> <id> <dlc> <data>*
180 * Extended frames (29 bit) are defined by capital characters in the type.
181 * RTR frames are defined as 'r' types - normal frames have 't' type:
182 * t => 11 bit data frame
183 * r => 11 bit RTR frame
184 * T => 29 bit data frame
185 * R => 29 bit RTR frame
187 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
188 * The <dlc> is a one byte ASCII number ('0' - '8')
189 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
193 * t1230 : can_id 0x123, can_dlc 0, no data
194 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
195 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
196 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
200 /************************************************************************
201 * STANDARD SLCAN DECAPSULATION *
202 ************************************************************************/
204 static int asc2nibble(char c)
207 if ((c >= '0') && (c <= '9'))
210 if ((c >= 'A') && (c <= 'F'))
213 if ((c >= 'a') && (c <= 'f'))
216 return 16; /* error */
219 /* Send one completely decapsulated can_frame to the network layer */
220 static void slc_bump(struct slcan *sl)
222 struct net_device_stats *stats = sl->dev->get_stats(sl->dev);
226 char cmd = sl->rbuff[0];
228 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
231 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
232 dlc_pos = 4; /* dlc position tiiid */
234 dlc_pos = 9; /* dlc position Tiiiiiiiid */
236 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
239 cf.can_dlc = sl->rbuff[dlc_pos] & 0x0F; /* get can_dlc */
241 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
243 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
244 cf.can_id = simple_strtoul(sl->rbuff+1, NULL, 16);
246 if (strict_strtoul(sl->rbuff+1, 16, (unsigned long *) &cf.can_id))
250 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
251 cf.can_id |= CAN_EFF_FLAG;
253 if ((cmd | 0x20) == 'r') /* RTR frame */
254 cf.can_id |= CAN_RTR_FLAG;
256 *(u64 *) (&cf.data) = 0; /* clear payload */
258 for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
260 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
263 cf.data[i] = (tmp << 4);
264 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
271 skb = dev_alloc_skb(sizeof(struct can_frame));
276 skb->protocol = htons(ETH_P_CAN);
277 skb->pkt_type = PACKET_BROADCAST;
278 skb->ip_summed = CHECKSUM_UNNECESSARY;
279 memcpy(skb_put(skb, sizeof(struct can_frame)),
280 &cf, sizeof(struct can_frame));
283 sl->dev->last_rx = jiffies;
285 stats->rx_bytes += cf.can_dlc;
288 /* parse tty input stream */
289 static void slcan_unesc(struct slcan *sl, unsigned char s)
291 struct net_device_stats *stats = sl->dev->get_stats(sl->dev);
293 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
294 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
300 if (!test_bit(SLF_ERROR, &sl->flags)) {
301 if (sl->rcount < SLC_MTU) {
302 sl->rbuff[sl->rcount++] = s;
305 stats->rx_over_errors++;
306 set_bit(SLF_ERROR, &sl->flags);
312 /************************************************************************
313 * STANDARD SLCAN ENCAPSULATION *
314 ************************************************************************/
316 /* Encapsulate one can_frame and stuff into a TTY queue. */
317 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
319 struct net_device_stats *stats = sl->dev->get_stats(sl->dev);
323 if (cf->can_id & CAN_RTR_FLAG)
324 cmd = 'R'; /* becomes 'r' in standard frame format */
326 cmd = 'T'; /* becomes 't' in standard frame format */
328 if (cf->can_id & CAN_EFF_FLAG)
329 sprintf(sl->xbuff, "%c%08X%d", cmd,
330 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
332 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
333 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
335 idx = strlen(sl->xbuff);
337 for (i = 0; i < cf->can_dlc; i++)
338 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
340 DBG("ASCII frame = '%s'\n", sl->xbuff);
342 strcat(sl->xbuff, "\r"); /* add terminating character */
344 /* Order of next two lines is *very* important.
345 * When we are sending a little amount of data,
346 * the transfer may be completed inside driver.write()
347 * routine, because it's running with interrupts enabled.
348 * In this case we *never* got WRITE_WAKEUP event,
349 * if we did not request it before write operation.
350 * 14 Oct 1994 Dmitry Gorodchanin.
352 sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
353 actual = sl->tty->driver->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
354 #ifdef SLC_CHECK_TRANSMIT
355 sl->dev->trans_start = jiffies;
357 sl->xleft = strlen(sl->xbuff) - actual;
358 sl->xhead = sl->xbuff + actual;
359 stats->tx_bytes += cf->can_dlc;
363 * Called by the driver when there's room for more data. If we have
364 * more packets to send, we send them here.
366 static void slcan_write_wakeup(struct tty_struct *tty)
369 struct slcan *sl = (struct slcan *) tty->disc_data;
370 struct net_device_stats *stats = sl->dev->get_stats(sl->dev);
372 /* First make sure we're connected. */
373 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
376 if (sl->xleft <= 0) {
377 /* Now serial buffer is almost free & we can start
378 * transmission of another packet */
380 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
381 netif_wake_queue(sl->dev);
385 actual = tty->driver->write(tty, sl->xhead, sl->xleft);
390 static void slc_tx_timeout(struct net_device *dev)
392 struct slcan *sl = netdev_priv(dev);
394 spin_lock(&sl->lock);
396 if (netif_queue_stopped(dev)) {
397 if (!netif_running(dev))
400 /* May be we must check transmitter timeout here ?
401 * 14 Oct 1994 Dmitry Gorodchanin.
403 #ifdef SLC_CHECK_TRANSMIT
404 if (time_before(jiffies, dev->trans_start + 20 * HZ)) {
405 /* 20 sec timeout not reached */
408 printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
409 (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft)
410 ? "bad line quality" : "driver error");
412 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
413 netif_wake_queue(sl->dev);
417 spin_unlock(&sl->lock);
421 /******************************************
422 * Routines looking at netdevice side.
423 ******************************************/
425 /* Send a can_frame to a TTY queue. */
426 static int slc_xmit(struct sk_buff *skb, struct net_device *dev)
428 struct slcan *sl = netdev_priv(dev);
430 if (skb->len != sizeof(struct can_frame))
433 spin_lock(&sl->lock);
434 if (!netif_running(dev)) {
435 spin_unlock(&sl->lock);
436 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
440 if (sl->tty == NULL) {
441 spin_unlock(&sl->lock);
445 netif_stop_queue(sl->dev);
446 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
447 spin_unlock(&sl->lock);
455 /* Netdevice UP -> DOWN routine */
456 static int slc_close(struct net_device *dev)
458 struct slcan *sl = netdev_priv(dev);
460 spin_lock_bh(&sl->lock);
462 /* TTY discipline is running. */
463 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
465 netif_stop_queue(dev);
468 spin_unlock_bh(&sl->lock);
473 /* Netdevice DOWN -> UP routine */
474 static int slc_open(struct net_device *dev)
476 struct slcan *sl = netdev_priv(dev);
481 sl->flags &= (1 << SLF_INUSE);
482 netif_start_queue(dev);
486 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
487 /* Netdevice get statistics request */
488 static struct net_device_stats *slc_get_stats(struct net_device *dev)
490 struct slcan *sl = netdev_priv(dev);
496 /* Netdevice register callback */
497 static void slc_setup(struct net_device *dev)
499 dev->open = slc_open;
500 dev->destructor = free_netdev;
501 dev->stop = slc_close;
502 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
503 dev->get_stats = slc_get_stats;
505 dev->hard_start_xmit = slc_xmit;
507 dev->hard_header_len = 0;
509 dev->tx_queue_len = 10;
511 dev->mtu = sizeof(struct can_frame);
512 dev->type = ARPHRD_CAN;
513 #ifdef SLC_CHECK_TRANSMIT
514 dev->tx_timeout = slc_tx_timeout;
515 dev->watchdog_timeo = 20*HZ;
518 /* New-style flags. */
519 dev->flags = IFF_NOARP;
520 dev->features = NETIF_F_NO_CSUM;
523 /******************************************
524 * Routines looking at TTY side.
525 ******************************************/
527 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
528 static int slcan_receive_room(struct tty_struct *tty)
530 return 65536; /* We can handle an infinite amount of data. :-) */
535 * Handle the 'receiver data ready' interrupt.
536 * This function is called by the 'tty_io' module in the kernel when
537 * a block of SLCAN data has been received, which can now be decapsulated
538 * and sent on to some IP layer for further processing. This will not
539 * be re-entered while running but other ldisc functions may be called
543 static void slcan_receive_buf(struct tty_struct *tty,
544 const unsigned char *cp, char *fp, int count)
546 struct slcan *sl = (struct slcan *) tty->disc_data;
547 struct net_device_stats *stats = sl->dev->get_stats(sl->dev);
549 if (!sl || sl->magic != SLCAN_MAGIC ||
550 !netif_running(sl->dev))
553 /* Read the characters out of the buffer */
556 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
561 slcan_unesc(sl, *cp++);
565 /************************************
566 * slcan_open helper routines.
567 ************************************/
569 /* Collect hanged up channels */
571 static void slc_sync(void)
574 struct net_device *dev;
577 for (i = 0; i < maxdev; i++) {
582 sl = netdev_priv(dev);
583 if (sl->tty || sl->leased)
585 if (dev->flags&IFF_UP)
591 /* Find a free SLCAN channel, and link in this `tty' line. */
592 static struct slcan *slc_alloc(dev_t line)
597 struct net_device *dev = NULL;
600 if (slcan_devs == NULL)
601 return NULL; /* Master array missing ! */
603 for (i = 0; i < maxdev; i++) {
608 sl = netdev_priv(dev);
610 if (sl->line != line)
615 /* Clear ESCAPE & ERROR flags */
616 sl->flags &= (1 << SLF_INUSE);
623 if (current->pid == sl->pid) {
624 if (sl->line == line && score < 3) {
635 if (sl->line == line && score < 1) {
650 sl = netdev_priv(dev);
651 sl->flags &= (1 << SLF_INUSE);
656 /* Sorry, too many, all slots in use */
661 sl = netdev_priv(dev);
662 if (test_bit(SLF_INUSE, &sl->flags)) {
663 unregister_netdevice(dev);
664 free_netdev(dev); /* new in slcan.c */
666 slcan_devs[i] = NULL;
672 sprintf(name, "slc%d", i);
674 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
680 sl = netdev_priv(dev);
682 /* Initialize channel control data */
683 sl->magic = SLCAN_MAGIC;
685 spin_lock_init(&sl->lock);
692 * Open the high-level part of the SLCAN channel.
693 * This function is called by the TTY module when the
694 * SLCAN line discipline is called for. Because we are
695 * sure the tty line exists, we only have to link it to
696 * a free SLCAN channel...
698 * Called in process context serialized from other ldisc calls.
701 static int slcan_open(struct tty_struct *tty)
706 if (!capable(CAP_NET_ADMIN))
709 /* RTnetlink lock is misused here to serialize concurrent
710 opens of slcan channels. There are better ways, but it is
715 /* Collect hanged up channels. */
718 sl = (struct slcan *) tty->disc_data;
721 /* First make sure we're not already connected. */
722 if (sl && sl->magic == SLCAN_MAGIC)
725 /* OK. Find a free SLCAN channel to use. */
727 sl = slc_alloc(tty_devnum(tty));
733 sl->line = tty_devnum(tty);
734 sl->pid = current->pid;
736 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
737 /* FIXME: already done before we were called - seems this can go */
738 if (tty->driver->flush_buffer)
739 tty->driver->flush_buffer(tty);
742 if (!test_bit(SLF_INUSE, &sl->flags)) {
743 /* Perform the low-level SLCAN initialization. */
747 set_bit(SLF_INUSE, &sl->flags);
749 err = register_netdevice(sl->dev);
754 /* Done. We have linked the TTY line to a channel. */
757 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
758 tty->receive_room = 65536; /* We don't flow control */
761 return sl->dev->base_addr;
765 tty->disc_data = NULL;
766 clear_bit(SLF_INUSE, &sl->flags);
771 /* Count references from TTY module */
777 FIXME: 1,2 are fixed 3 was never true anyway.
779 Let me to blame a bit.
780 1. TTY module calls this funstion on soft interrupt.
781 2. TTY module calls this function WITH MASKED INTERRUPTS!
782 3. TTY module does not notify us about line discipline
785 Seems, now it is clean. The solution is to consider netdevice and
786 line discipline sides as two independent threads.
788 By-product (not desired): slc? does not feel hangups and remains open.
789 It is supposed, that user level program (dip, diald, slattach...)
790 will catch SIGHUP and make the rest of work.
792 I see no way to make more with current tty code. --ANK
796 * Close down a SLCAN channel.
797 * This means flushing out any pending queues, and then returning. This
798 * call is serialized against other ldisc functions.
800 static void slcan_close(struct tty_struct *tty)
802 struct slcan *sl = (struct slcan *) tty->disc_data;
804 /* First make sure we're connected. */
805 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
808 tty->disc_data = NULL;
813 /* Count references from TTY module */
816 /* Perform I/O control on an active SLCAN channel. */
817 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
818 unsigned int cmd, unsigned long arg)
820 struct slcan *sl = (struct slcan *) tty->disc_data;
823 /* First make sure we're connected. */
824 if (!sl || sl->magic != SLCAN_MAGIC)
829 tmp = strlen(sl->dev->name) + 1;
830 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
838 /* Allow stty to read, but not set, the serial port */
841 return n_tty_ioctl(tty, file, cmd, arg);
848 static struct tty_ldisc slc_ldisc = {
849 .owner = THIS_MODULE,
850 .magic = TTY_LDISC_MAGIC,
853 .close = slcan_close,
854 .ioctl = slcan_ioctl,
855 .receive_buf = slcan_receive_buf,
856 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
857 .receive_room = slcan_receive_room,
859 .write_wakeup = slcan_write_wakeup,
862 /************************************
863 * general slcan module init/exit
864 ************************************/
866 static int __init slcan_init(void)
871 maxdev = 4; /* Sanity */
874 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
876 slcan_devs = kmalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
878 printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
882 /* Clear the pointer array, we allocate devices when we need them */
883 memset(slcan_devs, 0, sizeof(struct net_device *)*maxdev);
885 /* Fill in our line protocol discipline, and register it */
886 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
888 printk(KERN_ERR "slcan: can't register line discipline\n");
894 static void __exit slcan_exit(void)
897 struct net_device *dev;
899 unsigned long timeout = jiffies + HZ;
902 if (slcan_devs == NULL)
905 /* First of all: check for active disciplines and hangup them.
909 msleep_interruptible(100);
912 for (i = 0; i < maxdev; i++) {
916 sl = netdev_priv(dev);
917 spin_lock_bh(&sl->lock);
922 spin_unlock_bh(&sl->lock);
924 } while (busy && time_before(jiffies, timeout));
927 for (i = 0; i < maxdev; i++) {
931 slcan_devs[i] = NULL;
933 sl = netdev_priv(dev);
935 printk(KERN_ERR "%s: tty discipline still running\n",
937 /* Intentionally leak the control block. */
938 dev->destructor = NULL;
941 unregister_netdev(dev);
947 i = tty_unregister_ldisc(N_SLCAN);
949 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
952 module_init(slcan_init);
953 module_exit(slcan_exit);