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;
166 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
167 /* Netdevice get statistics request */
168 static struct net_device_stats *slc_get_stats(struct net_device *dev)
170 struct slcan *sl = netdev_priv(dev);
176 /************************************************************************
177 * SLCAN ENCAPSULATION FORMAT *
178 ************************************************************************/
181 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
182 * frame format) a data length code (can_dlc) which can be from 0 to 8
183 * and up to <can_dlc> data bytes as payload.
184 * Additionally a CAN frame may become a remote transmission frame if the
185 * RTR-bit is set. This causes another ECU to send a CAN frame with the
188 * The SLCAN ASCII representation of these different frame types is:
189 * <type> <id> <dlc> <data>*
191 * Extended frames (29 bit) are defined by capital characters in the type.
192 * RTR frames are defined as 'r' types - normal frames have 't' type:
193 * t => 11 bit data frame
194 * r => 11 bit RTR frame
195 * T => 29 bit data frame
196 * R => 29 bit RTR frame
198 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
199 * The <dlc> is a one byte ASCII number ('0' - '8')
200 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
204 * t1230 : can_id 0x123, can_dlc 0, no data
205 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
206 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
207 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
211 /************************************************************************
212 * STANDARD SLCAN DECAPSULATION *
213 ************************************************************************/
215 static int asc2nibble(char c)
218 if ((c >= '0') && (c <= '9'))
221 if ((c >= 'A') && (c <= 'F'))
224 if ((c >= 'a') && (c <= 'f'))
227 return 16; /* error */
230 /* Send one completely decapsulated can_frame to the network layer */
231 static void slc_bump(struct slcan *sl)
233 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
234 struct net_device_stats *stats = slc_get_stats(sl->dev);
236 struct net_device_stats *stats = &sl->dev->stats;
242 char cmd = sl->rbuff[0];
244 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
247 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
248 dlc_pos = 4; /* dlc position tiiid */
250 dlc_pos = 9; /* dlc position Tiiiiiiiid */
252 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
255 cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
257 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
259 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
260 ultmp = simple_strtoul(sl->rbuff+1, NULL, 16);
262 if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
267 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
268 cf.can_id |= CAN_EFF_FLAG;
270 if ((cmd | 0x20) == 'r') /* RTR frame */
271 cf.can_id |= CAN_RTR_FLAG;
273 *(u64 *) (&cf.data) = 0; /* clear payload */
275 for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
277 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
280 cf.data[i] = (tmp << 4);
281 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
288 skb = dev_alloc_skb(sizeof(struct can_frame));
293 skb->protocol = htons(ETH_P_CAN);
294 skb->pkt_type = PACKET_BROADCAST;
295 skb->ip_summed = CHECKSUM_UNNECESSARY;
296 memcpy(skb_put(skb, sizeof(struct can_frame)),
297 &cf, sizeof(struct can_frame));
300 sl->dev->last_rx = jiffies;
302 stats->rx_bytes += cf.can_dlc;
305 /* parse tty input stream */
306 static void slcan_unesc(struct slcan *sl, unsigned char s)
308 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
309 struct net_device_stats *stats = slc_get_stats(sl->dev);
311 struct net_device_stats *stats = &sl->dev->stats;
314 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
315 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
321 if (!test_bit(SLF_ERROR, &sl->flags)) {
322 if (sl->rcount < SLC_MTU) {
323 sl->rbuff[sl->rcount++] = s;
326 stats->rx_over_errors++;
327 set_bit(SLF_ERROR, &sl->flags);
333 /************************************************************************
334 * STANDARD SLCAN ENCAPSULATION *
335 ************************************************************************/
337 /* Encapsulate one can_frame and stuff into a TTY queue. */
338 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
340 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
341 struct net_device_stats *stats = slc_get_stats(sl->dev);
343 struct net_device_stats *stats = &sl->dev->stats;
348 if (cf->can_id & CAN_RTR_FLAG)
349 cmd = 'R'; /* becomes 'r' in standard frame format */
351 cmd = 'T'; /* becomes 't' in standard frame format */
353 if (cf->can_id & CAN_EFF_FLAG)
354 sprintf(sl->xbuff, "%c%08X%d", cmd,
355 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
357 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
358 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
360 idx = strlen(sl->xbuff);
362 for (i = 0; i < cf->can_dlc; i++)
363 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
365 DBG("ASCII frame = '%s'\n", sl->xbuff);
367 strcat(sl->xbuff, "\r"); /* add terminating character */
369 /* Order of next two lines is *very* important.
370 * When we are sending a little amount of data,
371 * the transfer may be completed inside driver.write()
372 * routine, because it's running with interrupts enabled.
373 * In this case we *never* got WRITE_WAKEUP event,
374 * if we did not request it before write operation.
375 * 14 Oct 1994 Dmitry Gorodchanin.
377 sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
378 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,26)
379 actual = sl->tty->driver->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
381 actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
383 #ifdef SLC_CHECK_TRANSMIT
384 sl->dev->trans_start = jiffies;
386 sl->xleft = strlen(sl->xbuff) - actual;
387 sl->xhead = sl->xbuff + actual;
388 stats->tx_bytes += cf->can_dlc;
392 * Called by the driver when there's room for more data. If we have
393 * more packets to send, we send them here.
395 static void slcan_write_wakeup(struct tty_struct *tty)
398 struct slcan *sl = (struct slcan *) tty->disc_data;
399 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
400 struct net_device_stats *stats = slc_get_stats(sl->dev);
402 struct net_device_stats *stats = &sl->dev->stats;
405 /* First make sure we're connected. */
406 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
409 if (sl->xleft <= 0) {
410 /* Now serial buffer is almost free & we can start
411 * transmission of another packet */
413 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
414 netif_wake_queue(sl->dev);
418 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,26)
419 actual = tty->driver->write(tty, sl->xhead, sl->xleft);
421 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
427 static void slc_tx_timeout(struct net_device *dev)
429 struct slcan *sl = netdev_priv(dev);
431 spin_lock(&sl->lock);
433 if (netif_queue_stopped(dev)) {
434 if (!netif_running(dev))
437 /* May be we must check transmitter timeout here ?
438 * 14 Oct 1994 Dmitry Gorodchanin.
440 #ifdef SLC_CHECK_TRANSMIT
441 if (time_before(jiffies, dev->trans_start + 20 * HZ)) {
442 /* 20 sec timeout not reached */
445 printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
446 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,26)
447 (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft)
449 (tty_chars_in_buffer(sl->tty) || sl->xleft)
451 ? "bad line quality" : "driver error");
453 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
454 netif_wake_queue(sl->dev);
458 spin_unlock(&sl->lock);
462 /******************************************
463 * Routines looking at netdevice side.
464 ******************************************/
466 /* Send a can_frame to a TTY queue. */
467 static int slc_xmit(struct sk_buff *skb, struct net_device *dev)
469 struct slcan *sl = netdev_priv(dev);
471 if (skb->len != sizeof(struct can_frame))
474 spin_lock(&sl->lock);
475 if (!netif_running(dev)) {
476 spin_unlock(&sl->lock);
477 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
481 if (sl->tty == NULL) {
482 spin_unlock(&sl->lock);
486 netif_stop_queue(sl->dev);
487 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
488 spin_unlock(&sl->lock);
496 /* Netdevice UP -> DOWN routine */
497 static int slc_close(struct net_device *dev)
499 struct slcan *sl = netdev_priv(dev);
501 spin_lock_bh(&sl->lock);
503 /* TTY discipline is running. */
504 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
506 netif_stop_queue(dev);
509 spin_unlock_bh(&sl->lock);
514 /* Netdevice DOWN -> UP routine */
515 static int slc_open(struct net_device *dev)
517 struct slcan *sl = netdev_priv(dev);
522 sl->flags &= (1 << SLF_INUSE);
523 netif_start_queue(dev);
527 /* Netdevice register callback */
528 static void slc_setup(struct net_device *dev)
530 dev->open = slc_open;
531 dev->destructor = free_netdev;
532 dev->stop = slc_close;
533 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
534 dev->get_stats = slc_get_stats;
536 dev->hard_start_xmit = slc_xmit;
538 dev->hard_header_len = 0;
540 dev->tx_queue_len = 10;
542 dev->mtu = sizeof(struct can_frame);
543 dev->type = ARPHRD_CAN;
544 #ifdef SLC_CHECK_TRANSMIT
545 dev->tx_timeout = slc_tx_timeout;
546 dev->watchdog_timeo = 20*HZ;
549 /* New-style flags. */
550 dev->flags = IFF_NOARP;
551 dev->features = NETIF_F_NO_CSUM;
554 /******************************************
555 * Routines looking at TTY side.
556 ******************************************/
558 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
559 static int slcan_receive_room(struct tty_struct *tty)
561 return 65536; /* We can handle an infinite amount of data. :-) */
566 * Handle the 'receiver data ready' interrupt.
567 * This function is called by the 'tty_io' module in the kernel when
568 * a block of SLCAN data has been received, which can now be decapsulated
569 * and sent on to some IP layer for further processing. This will not
570 * be re-entered while running but other ldisc functions may be called
574 static void slcan_receive_buf(struct tty_struct *tty,
575 const unsigned char *cp, char *fp, int count)
577 struct slcan *sl = (struct slcan *) tty->disc_data;
578 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
579 struct net_device_stats *stats = slc_get_stats(sl->dev);
581 struct net_device_stats *stats = &sl->dev->stats;
584 if (!sl || sl->magic != SLCAN_MAGIC ||
585 !netif_running(sl->dev))
588 /* Read the characters out of the buffer */
591 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
596 slcan_unesc(sl, *cp++);
600 /************************************
601 * slcan_open helper routines.
602 ************************************/
604 /* Collect hanged up channels */
606 static void slc_sync(void)
609 struct net_device *dev;
612 for (i = 0; i < maxdev; i++) {
617 sl = netdev_priv(dev);
618 if (sl->tty || sl->leased)
620 if (dev->flags&IFF_UP)
626 /* Find a free SLCAN channel, and link in this `tty' line. */
627 static struct slcan *slc_alloc(dev_t line)
632 struct net_device *dev = NULL;
635 if (slcan_devs == NULL)
636 return NULL; /* Master array missing ! */
638 for (i = 0; i < maxdev; i++) {
643 sl = netdev_priv(dev);
645 if (sl->line != line)
650 /* Clear ESCAPE & ERROR flags */
651 sl->flags &= (1 << SLF_INUSE);
658 if (current->pid == sl->pid) {
659 if (sl->line == line && score < 3) {
670 if (sl->line == line && score < 1) {
685 sl = netdev_priv(dev);
686 sl->flags &= (1 << SLF_INUSE);
691 /* Sorry, too many, all slots in use */
696 sl = netdev_priv(dev);
697 if (test_bit(SLF_INUSE, &sl->flags)) {
698 unregister_netdevice(dev);
700 slcan_devs[i] = NULL;
706 sprintf(name, "slc%d", i);
708 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
714 sl = netdev_priv(dev);
716 /* Initialize channel control data */
717 sl->magic = SLCAN_MAGIC;
719 spin_lock_init(&sl->lock);
726 * Open the high-level part of the SLCAN channel.
727 * This function is called by the TTY module when the
728 * SLCAN line discipline is called for. Because we are
729 * sure the tty line exists, we only have to link it to
730 * a free SLCAN channel...
732 * Called in process context serialized from other ldisc calls.
735 static int slcan_open(struct tty_struct *tty)
740 if (!capable(CAP_NET_ADMIN))
743 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,25)
744 if (tty->ops->write == NULL)
748 /* RTnetlink lock is misused here to serialize concurrent
749 opens of slcan channels. There are better ways, but it is
754 /* Collect hanged up channels. */
757 sl = (struct slcan *) tty->disc_data;
760 /* First make sure we're not already connected. */
761 if (sl && sl->magic == SLCAN_MAGIC)
764 /* OK. Find a free SLCAN channel to use. */
766 sl = slc_alloc(tty_devnum(tty));
772 sl->line = tty_devnum(tty);
773 sl->pid = current->pid;
775 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
776 /* FIXME: already done before we were called - seems this can go */
777 if (tty->driver->flush_buffer)
778 tty->driver->flush_buffer(tty);
781 if (!test_bit(SLF_INUSE, &sl->flags)) {
782 /* Perform the low-level SLCAN initialization. */
786 set_bit(SLF_INUSE, &sl->flags);
788 err = register_netdevice(sl->dev);
793 /* Done. We have linked the TTY line to a channel. */
796 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
797 tty->receive_room = 65536; /* We don't flow control */
800 return sl->dev->base_addr;
804 tty->disc_data = NULL;
805 clear_bit(SLF_INUSE, &sl->flags);
810 /* Count references from TTY module */
816 FIXME: 1,2 are fixed 3 was never true anyway.
818 Let me to blame a bit.
819 1. TTY module calls this funstion on soft interrupt.
820 2. TTY module calls this function WITH MASKED INTERRUPTS!
821 3. TTY module does not notify us about line discipline
824 Seems, now it is clean. The solution is to consider netdevice and
825 line discipline sides as two independent threads.
827 By-product (not desired): slc? does not feel hangups and remains open.
828 It is supposed, that user level program (dip, diald, slattach...)
829 will catch SIGHUP and make the rest of work.
831 I see no way to make more with current tty code. --ANK
835 * Close down a SLCAN channel.
836 * This means flushing out any pending queues, and then returning. This
837 * call is serialized against other ldisc functions.
839 static void slcan_close(struct tty_struct *tty)
841 struct slcan *sl = (struct slcan *) tty->disc_data;
843 /* First make sure we're connected. */
844 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
847 tty->disc_data = NULL;
852 /* Count references from TTY module */
855 /* Perform I/O control on an active SLCAN channel. */
856 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
857 unsigned int cmd, unsigned long arg)
859 struct slcan *sl = (struct slcan *) tty->disc_data;
862 /* First make sure we're connected. */
863 if (!sl || sl->magic != SLCAN_MAGIC)
868 tmp = strlen(sl->dev->name) + 1;
869 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
876 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
877 /* Allow stty to read, but not set, the serial port */
880 return n_tty_ioctl(tty, file, cmd, arg);
886 return tty_mode_ioctl(tty, file, cmd, arg);
891 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
892 static struct tty_ldisc slc_ldisc = {
894 static struct tty_ldisc_ops slc_ldisc = {
896 .owner = THIS_MODULE,
897 .magic = TTY_LDISC_MAGIC,
900 .close = slcan_close,
901 .ioctl = slcan_ioctl,
902 .receive_buf = slcan_receive_buf,
903 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
904 .receive_room = slcan_receive_room,
906 .write_wakeup = slcan_write_wakeup,
909 /************************************
910 * general slcan module init/exit
911 ************************************/
913 static int __init slcan_init(void)
918 maxdev = 4; /* Sanity */
921 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
923 slcan_devs = kmalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
925 printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
929 /* Clear the pointer array, we allocate devices when we need them */
930 memset(slcan_devs, 0, sizeof(struct net_device *)*maxdev);
932 /* Fill in our line protocol discipline, and register it */
933 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
935 printk(KERN_ERR "slcan: can't register line discipline\n");
941 static void __exit slcan_exit(void)
944 struct net_device *dev;
946 unsigned long timeout = jiffies + HZ;
949 if (slcan_devs == NULL)
952 /* First of all: check for active disciplines and hangup them.
956 msleep_interruptible(100);
959 for (i = 0; i < maxdev; i++) {
963 sl = netdev_priv(dev);
964 spin_lock_bh(&sl->lock);
969 spin_unlock_bh(&sl->lock);
971 } while (busy && time_before(jiffies, timeout));
974 for (i = 0; i < maxdev; i++) {
978 slcan_devs[i] = NULL;
980 sl = netdev_priv(dev);
982 printk(KERN_ERR "%s: tty discipline still running\n",
984 /* Intentionally leak the control block. */
985 dev->destructor = NULL;
988 unregister_netdev(dev);
994 i = tty_unregister_ldisc(N_SLCAN);
996 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
999 module_init(slcan_init);
1000 module_exit(slcan_exit);