2 * slcan.c - serial line CAN interface driver (using tty line discipline)
4 * This file is derived from linux/drivers/net/slip.c
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>
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.
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.
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
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
38 * Send feedback to <socketcan-users@lists.berlios.de>
42 #include <linux/version.h>
43 #include <linux/module.h>
44 #include <linux/moduleparam.h>
46 #include <asm/system.h>
47 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,17)
48 #include <linux/uaccess.h>
50 #include <asm/uaccess.h>
52 #include <linux/bitops.h>
53 #include <linux/sched.h>
54 #include <linux/string.h>
56 #include <linux/interrupt.h>
58 #include <linux/tty.h>
59 #include <linux/errno.h>
60 #include <linux/netdevice.h>
61 #include <linux/etherdevice.h>
62 #include <linux/skbuff.h>
63 #include <linux/rtnetlink.h>
64 #include <linux/if_arp.h>
65 #include <linux/if_ether.h>
66 #include <linux/if_slip.h>
67 #include <linux/delay.h>
68 #include <linux/init.h>
70 #include <socketcan/can.h>
72 #include <socketcan/can/version.h> /* for RCSID. Removed by mkpatch script */
75 static __initdata const char banner[] =
76 KERN_INFO "slcan: serial line CAN interface driver\n";
78 MODULE_ALIAS_LDISC(N_SLCAN);
79 MODULE_DESCRIPTION("serial line CAN interface");
80 MODULE_LICENSE("GPL");
81 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
84 #error Your kernel does not support tty line discipline N_SLCAN
87 * As there is currently no line discipline N_SLCAN in the mainstream kernel
88 * you will have to modify two kernel includes & recompile the kernel.
90 * Add this in include/asm/termios.h after the definition of N_HCI:
93 * Increment NR_LDICS in include/linux/tty.h from 16 to 17
95 * NEW: Since Kernel 2.6.21 you only have to change include/linux/tty.h
97 * HACK for precompiled Kernels:
99 * In order to use the slcan driver without rebuilding the kernel, the slcan
100 * driver must be compiled to use an existing line discipline.
101 * The N_MOUSE line discipline is documented to be free for custom use and
102 * using it *should* not cause any side effect.
104 * Then, before compiling the slcan driver, add a -DN_SLCAN=N_MOUSE
105 * compilation option in its Makefile. The slcan_attach tool must(!!) also be
106 * rebuild to use the right value for N_SLCAN. This workaround will allow
107 * to use the slcan driver with an existing kernel.
110 #define SLCAN_MAGIC 0x53CA
112 static int maxdev = 10; /* MAX number of SLCAN channels;
113 This can be overridden with
114 insmod slcan.ko maxdev=nnn */
115 module_param(maxdev, int, 0);
116 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
118 /* maximum rx buffer len: extended CAN frame with timestamp */
119 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
124 /* Various fields. */
125 struct tty_struct *tty; /* ptr to TTY structure */
126 struct net_device *dev; /* easy for intr handling */
129 /* These are pointers to the malloc()ed frame buffers. */
130 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
131 int rcount; /* received chars counter */
132 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
133 unsigned char *xhead; /* pointer to next XMIT byte */
134 int xleft; /* bytes left in XMIT queue */
136 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
137 /* SLCAN interface statistics. */
138 struct net_device_stats stats;
141 unsigned long flags; /* Flag values/ mode etc */
142 #define SLF_INUSE 0 /* Channel in use */
143 #define SLF_ERROR 1 /* Parity, etc. error */
145 unsigned char leased;
150 static struct net_device **slcan_devs;
153 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
154 /* Netdevice get statistics request */
155 static struct net_device_stats *slc_get_stats(struct net_device *dev)
157 struct slcan *sl = netdev_priv(dev);
163 /************************************************************************
164 * SLCAN ENCAPSULATION FORMAT *
165 ************************************************************************/
168 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
169 * frame format) a data length code (can_dlc) which can be from 0 to 8
170 * and up to <can_dlc> data bytes as payload.
171 * Additionally a CAN frame may become a remote transmission frame if the
172 * RTR-bit is set. This causes another ECU to send a CAN frame with the
175 * The SLCAN ASCII representation of these different frame types is:
176 * <type> <id> <dlc> <data>*
178 * Extended frames (29 bit) are defined by capital characters in the type.
179 * RTR frames are defined as 'r' types - normal frames have 't' type:
180 * t => 11 bit data frame
181 * r => 11 bit RTR frame
182 * T => 29 bit data frame
183 * R => 29 bit RTR frame
185 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
186 * The <dlc> is a one byte ASCII number ('0' - '8')
187 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
191 * t1230 : can_id 0x123, can_dlc 0, no data
192 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
193 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
194 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
198 /************************************************************************
199 * STANDARD SLCAN DECAPSULATION *
200 ************************************************************************/
202 static int asc2nibble(char c)
205 if ((c >= '0') && (c <= '9'))
208 if ((c >= 'A') && (c <= 'F'))
211 if ((c >= 'a') && (c <= 'f'))
214 return 16; /* error */
217 /* Send one completely decapsulated can_frame to the network layer */
218 static void slc_bump(struct slcan *sl)
220 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
221 struct net_device_stats *stats = slc_get_stats(sl->dev);
223 struct net_device_stats *stats = &sl->dev->stats;
229 char cmd = sl->rbuff[0];
231 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
234 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
235 dlc_pos = 4; /* dlc position tiiid */
237 dlc_pos = 9; /* dlc position Tiiiiiiiid */
239 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
242 cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
244 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
246 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
247 ultmp = simple_strtoul(sl->rbuff+1, NULL, 16);
249 if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
254 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
255 cf.can_id |= CAN_EFF_FLAG;
257 if ((cmd | 0x20) == 'r') /* RTR frame */
258 cf.can_id |= CAN_RTR_FLAG;
260 *(u64 *) (&cf.data) = 0; /* clear payload */
262 for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
264 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
267 cf.data[i] = (tmp << 4);
268 tmp = asc2nibble(sl->rbuff[dlc_pos++]);
275 skb = dev_alloc_skb(sizeof(struct can_frame));
280 skb->protocol = htons(ETH_P_CAN);
281 skb->pkt_type = PACKET_BROADCAST;
282 skb->ip_summed = CHECKSUM_UNNECESSARY;
283 memcpy(skb_put(skb, sizeof(struct can_frame)),
284 &cf, sizeof(struct can_frame));
287 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,32)
288 sl->dev->last_rx = jiffies;
291 stats->rx_bytes += cf.can_dlc;
294 /* parse tty input stream */
295 static void slcan_unesc(struct slcan *sl, unsigned char s)
297 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
298 struct net_device_stats *stats = slc_get_stats(sl->dev);
300 struct net_device_stats *stats = &sl->dev->stats;
303 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
304 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
310 if (!test_bit(SLF_ERROR, &sl->flags)) {
311 if (sl->rcount < SLC_MTU) {
312 sl->rbuff[sl->rcount++] = s;
315 stats->rx_over_errors++;
316 set_bit(SLF_ERROR, &sl->flags);
322 /************************************************************************
323 * STANDARD SLCAN ENCAPSULATION *
324 ************************************************************************/
326 /* Encapsulate one can_frame and stuff into a TTY queue. */
327 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
329 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
330 struct net_device_stats *stats = slc_get_stats(sl->dev);
332 struct net_device_stats *stats = &sl->dev->stats;
337 if (cf->can_id & CAN_RTR_FLAG)
338 cmd = 'R'; /* becomes 'r' in standard frame format */
340 cmd = 'T'; /* becomes 't' in standard frame format */
342 if (cf->can_id & CAN_EFF_FLAG)
343 sprintf(sl->xbuff, "%c%08X%d", cmd,
344 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
346 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
347 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
349 idx = strlen(sl->xbuff);
351 for (i = 0; i < cf->can_dlc; i++)
352 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
354 strcat(sl->xbuff, "\r"); /* add terminating character */
356 /* Order of next two lines is *very* important.
357 * When we are sending a little amount of data,
358 * the transfer may be completed inside driver.write()
359 * routine, because it's running with interrupts enabled.
360 * In this case we *never* got WRITE_WAKEUP event,
361 * if we did not request it before write operation.
362 * 14 Oct 1994 Dmitry Gorodchanin.
364 sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
365 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,26)
366 actual = sl->tty->driver->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
368 actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
370 sl->xleft = strlen(sl->xbuff) - actual;
371 sl->xhead = sl->xbuff + actual;
372 stats->tx_bytes += cf->can_dlc;
376 * Called by the driver when there's room for more data. If we have
377 * more packets to send, we send them here.
379 static void slcan_write_wakeup(struct tty_struct *tty)
382 struct slcan *sl = (struct slcan *) tty->disc_data;
383 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
384 struct net_device_stats *stats = slc_get_stats(sl->dev);
386 struct net_device_stats *stats = &sl->dev->stats;
389 /* First make sure we're connected. */
390 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
393 if (sl->xleft <= 0) {
394 /* Now serial buffer is almost free & we can start
395 * transmission of another packet */
397 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
398 netif_wake_queue(sl->dev);
402 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,26)
403 actual = tty->driver->write(tty, sl->xhead, sl->xleft);
405 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
412 /******************************************
413 * Routines looking at netdevice side.
414 ******************************************/
416 /* Send a can_frame to a TTY queue. */
417 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,32)
418 static int slc_xmit(struct sk_buff *skb, struct net_device *dev)
420 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
423 struct slcan *sl = netdev_priv(dev);
425 if (skb->len != sizeof(struct can_frame))
428 spin_lock(&sl->lock);
429 if (!netif_running(dev)) {
430 spin_unlock(&sl->lock);
431 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
435 if (sl->tty == NULL) {
436 spin_unlock(&sl->lock);
440 netif_stop_queue(sl->dev);
441 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
442 spin_unlock(&sl->lock);
446 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,32)
454 /* Netdevice UP -> DOWN routine */
455 static int slc_close(struct net_device *dev)
457 struct slcan *sl = netdev_priv(dev);
459 spin_lock_bh(&sl->lock);
461 /* TTY discipline is running. */
462 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
464 netif_stop_queue(dev);
467 spin_unlock_bh(&sl->lock);
472 /* Netdevice DOWN -> UP routine */
473 static int slc_open(struct net_device *dev)
475 struct slcan *sl = netdev_priv(dev);
480 sl->flags &= (1 << SLF_INUSE);
481 netif_start_queue(dev);
485 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,31)
486 /* Hook the destructor so we can free slcan devs at the right point in time */
487 static void slc_free_netdev(struct net_device *dev)
489 int i = dev->base_addr;
491 slcan_devs[i] = NULL;
495 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,28)
496 static const struct net_device_ops slc_netdev_ops = {
497 .ndo_open = slc_open,
498 .ndo_stop = slc_close,
499 .ndo_start_xmit = slc_xmit,
503 /* Netdevice register callback */
504 static void slc_setup(struct net_device *dev)
506 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,28)
507 dev->netdev_ops = &slc_netdev_ops;
509 dev->open = slc_open;
510 dev->stop = slc_close;
511 dev->hard_start_xmit = slc_xmit;
513 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,31)
514 dev->destructor = slc_free_netdev;
516 dev->destructor = free_netdev;
518 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
519 dev->get_stats = slc_get_stats;
522 dev->hard_header_len = 0;
524 dev->tx_queue_len = 10;
526 dev->mtu = sizeof(struct can_frame);
527 dev->type = ARPHRD_CAN;
529 /* New-style flags. */
530 dev->flags = IFF_NOARP;
531 dev->features = NETIF_F_NO_CSUM;
534 /******************************************
535 * Routines looking at TTY side.
536 ******************************************/
538 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
539 static int slcan_receive_room(struct tty_struct *tty)
541 return 65536; /* We can handle an infinite amount of data. :-) */
546 * Handle the 'receiver data ready' interrupt.
547 * This function is called by the 'tty_io' module in the kernel when
548 * a block of SLCAN data has been received, which can now be decapsulated
549 * and sent on to some IP layer for further processing. This will not
550 * be re-entered while running but other ldisc functions may be called
554 static void slcan_receive_buf(struct tty_struct *tty,
555 const unsigned char *cp, char *fp, int count)
557 struct slcan *sl = (struct slcan *) tty->disc_data;
558 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
559 struct net_device_stats *stats = slc_get_stats(sl->dev);
561 struct net_device_stats *stats = &sl->dev->stats;
564 if (!sl || sl->magic != SLCAN_MAGIC ||
565 !netif_running(sl->dev))
568 /* Read the characters out of the buffer */
571 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
576 slcan_unesc(sl, *cp++);
580 /************************************
581 * slcan_open helper routines.
582 ************************************/
584 /* Collect hanged up channels */
586 static void slc_sync(void)
589 struct net_device *dev;
592 for (i = 0; i < maxdev; i++) {
597 sl = netdev_priv(dev);
598 if (sl->tty || sl->leased)
600 if (dev->flags&IFF_UP)
606 /* Find a free SLCAN channel, and link in this `tty' line. */
607 static struct slcan *slc_alloc(dev_t line)
612 struct net_device *dev = NULL;
615 if (slcan_devs == NULL)
616 return NULL; /* Master array missing ! */
618 for (i = 0; i < maxdev; i++) {
623 sl = netdev_priv(dev);
625 if (sl->line != line)
630 /* Clear ESCAPE & ERROR flags */
631 sl->flags &= (1 << SLF_INUSE);
638 if (current->pid == sl->pid) {
639 if (sl->line == line && score < 3) {
650 if (sl->line == line && score < 1) {
665 sl = netdev_priv(dev);
666 sl->flags &= (1 << SLF_INUSE);
671 /* Sorry, too many, all slots in use */
676 sl = netdev_priv(dev);
677 if (test_bit(SLF_INUSE, &sl->flags)) {
678 unregister_netdevice(dev);
680 slcan_devs[i] = NULL;
686 sprintf(name, "slcan%d", i);
688 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
694 sl = netdev_priv(dev);
696 /* Initialize channel control data */
697 sl->magic = SLCAN_MAGIC;
699 spin_lock_init(&sl->lock);
706 * Open the high-level part of the SLCAN channel.
707 * This function is called by the TTY module when the
708 * SLCAN line discipline is called for. Because we are
709 * sure the tty line exists, we only have to link it to
710 * a free SLCAN channel...
712 * Called in process context serialized from other ldisc calls.
715 static int slcan_open(struct tty_struct *tty)
720 if (!capable(CAP_NET_ADMIN))
723 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,25)
724 if (tty->ops->write == NULL)
728 /* RTnetlink lock is misused here to serialize concurrent
729 opens of slcan channels. There are better ways, but it is
734 /* Collect hanged up channels. */
737 sl = (struct slcan *) tty->disc_data;
740 /* First make sure we're not already connected. */
741 if (sl && sl->magic == SLCAN_MAGIC)
744 /* OK. Find a free SLCAN channel to use. */
746 sl = slc_alloc(tty_devnum(tty));
752 sl->line = tty_devnum(tty);
753 sl->pid = current->pid;
755 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
756 /* FIXME: already done before we were called - seems this can go */
757 if (tty->driver->flush_buffer)
758 tty->driver->flush_buffer(tty);
761 if (!test_bit(SLF_INUSE, &sl->flags)) {
762 /* Perform the low-level SLCAN initialization. */
766 set_bit(SLF_INUSE, &sl->flags);
768 err = register_netdevice(sl->dev);
773 /* Done. We have linked the TTY line to a channel. */
776 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
777 tty->receive_room = 65536; /* We don't flow control */
780 return sl->dev->base_addr;
784 tty->disc_data = NULL;
785 clear_bit(SLF_INUSE, &sl->flags);
790 /* Count references from TTY module */
795 * Close down a SLCAN channel.
796 * This means flushing out any pending queues, and then returning. This
797 * call is serialized against other ldisc functions.
799 * We also use this method for a hangup event.
801 static void slcan_close(struct tty_struct *tty)
803 struct slcan *sl = (struct slcan *) tty->disc_data;
805 /* First make sure we're connected. */
806 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
809 tty->disc_data = NULL;
814 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,31)
815 /* Flush network side */
816 unregister_netdev(sl->dev);
817 /* This will complete via sl_free_netdev */
819 /* Count references from TTY module */
823 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,31)
824 static int slcan_hangup(struct tty_struct *tty)
831 /* Perform I/O control on an active SLCAN channel. */
832 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
833 unsigned int cmd, unsigned long arg)
835 struct slcan *sl = (struct slcan *) tty->disc_data;
838 /* First make sure we're connected. */
839 if (!sl || sl->magic != SLCAN_MAGIC)
844 tmp = strlen(sl->dev->name) + 1;
845 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
852 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
853 /* Allow stty to read, but not set, the serial port */
856 return n_tty_ioctl(tty, file, cmd, arg);
862 return tty_mode_ioctl(tty, file, cmd, arg);
867 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
868 static struct tty_ldisc slc_ldisc = {
870 static struct tty_ldisc_ops slc_ldisc = {
872 .owner = THIS_MODULE,
873 .magic = TTY_LDISC_MAGIC,
876 .close = slcan_close,
877 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,31)
878 .hangup = slcan_hangup,
880 .ioctl = slcan_ioctl,
881 .receive_buf = slcan_receive_buf,
882 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
883 .receive_room = slcan_receive_room,
885 .write_wakeup = slcan_write_wakeup,
888 /************************************
889 * general slcan module init/exit
890 ************************************/
892 static int __init slcan_init(void)
897 maxdev = 4; /* Sanity */
900 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
902 slcan_devs = kmalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
904 printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
908 /* Clear the pointer array, we allocate devices when we need them */
909 memset(slcan_devs, 0, sizeof(struct net_device *)*maxdev);
911 /* Fill in our line protocol discipline, and register it */
912 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
914 printk(KERN_ERR "slcan: can't register line discipline\n");
920 static void __exit slcan_exit(void)
923 struct net_device *dev;
925 unsigned long timeout = jiffies + HZ;
928 if (slcan_devs == NULL)
931 /* First of all: check for active disciplines and hangup them.
935 msleep_interruptible(100);
938 for (i = 0; i < maxdev; i++) {
942 sl = netdev_priv(dev);
943 spin_lock_bh(&sl->lock);
948 spin_unlock_bh(&sl->lock);
950 } while (busy && time_before(jiffies, timeout));
952 /* FIXME (2.6.32+): hangup is async so we should wait when doing
955 for (i = 0; i < maxdev; i++) {
959 slcan_devs[i] = NULL;
961 sl = netdev_priv(dev);
963 printk(KERN_ERR "%s: tty discipline still running\n",
965 /* Intentionally leak the control block. */
966 dev->destructor = NULL;
969 unregister_netdev(dev);
975 i = tty_unregister_ldisc(N_SLCAN);
977 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
980 module_init(slcan_init);
981 module_exit(slcan_exit);