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, the following disclaimer and
12 * the referenced file 'COPYING'.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of Volkswagen nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * Alternatively, provided that this notice is retained in full, this
21 * software may be distributed under the terms of the GNU General
22 * Public License ("GPL") version 2 as distributed in the 'COPYING'
23 * file from the main directory of the linux kernel source.
25 * The provided data structures and external interfaces from this code
26 * are not restricted to be used by modules with a GPL compatible license.
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
41 * Send feedback to <socketcan-users@lists.berlios.de>
46 * This file is derived from linux/drivers/net/slip.c
48 * Therefore it has the same (strange?) behaviour not to unregister the
49 * netdevice when detaching the tty. Is there any better solution?
51 * Do not try to attach, detach and re-attach a tty for this reason ...
53 * slip.c Authors: Laurence Culhane, <loz@holmes.demon.co.uk>
54 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
57 #include <linux/module.h>
58 #include <linux/moduleparam.h>
60 #include <asm/system.h>
61 #include <asm/uaccess.h>
62 #include <linux/bitops.h>
63 #include <linux/string.h>
65 #include <linux/interrupt.h>
67 #include <linux/tty.h>
68 #include <linux/errno.h>
69 #include <linux/netdevice.h>
70 #include <linux/etherdevice.h>
71 #include <linux/skbuff.h>
72 #include <linux/rtnetlink.h>
73 #include <linux/if_arp.h>
74 #include <linux/if_ether.h>
75 #include <linux/if_slip.h>
76 #include <linux/delay.h>
77 #include <linux/init.h>
79 #include <linux/can.h>
81 #include <linux/can/version.h> /* for RCSID. Removed by mkpatch script */
84 static __initdata const char banner[] =
85 KERN_INFO "CAN: serial line CAN interface " CAN_VERSION "\n";
87 MODULE_ALIAS_LDISC(N_SLCAN);
88 MODULE_DESCRIPTION("serial line CAN interface");
89 MODULE_LICENSE("Dual BSD/GPL");
90 MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
92 #ifdef CONFIG_CAN_DEBUG_DEVICES
94 module_param(debug, int, S_IRUGO);
95 #define DBG(args...) (debug & 1 ? \
96 (printk(KERN_DEBUG "slcan %s: ", __func__), \
103 #error Your kernel does not support tty line discipline N_SLCAN
106 * As there is currently no line discipline N_SLCAN in the mainstream kernel
107 * you will have to modify two kernel includes & recompile the kernel.
109 * Add this in include/asm/termios.h after the definition of N_HCI:
112 * Increment NR_LDICS in include/linux/tty.h from 16 to 17
114 * NEW: Since Kernel 2.6.21 you only have to change include/linux/tty.h
118 #define SLC_CHECK_TRANSMIT
119 #define SLCAN_MAGIC 0x53CA
121 static int maxdev = 10; /* MAX number of SLCAN channels;
122 This can be overridden with
123 insmod slcan.ko maxdev=nnn */
124 module_param(maxdev, int, 0);
125 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
127 /* maximum rx buffer len: extended CAN frame with timestamp */
128 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
133 /* Various fields. */
134 struct tty_struct *tty; /* ptr to TTY structure */
135 struct net_device *dev; /* easy for intr handling */
138 /* These are pointers to the malloc()ed frame buffers. */
139 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
140 int rcount; /* received chars counter */
141 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
142 unsigned char *xhead; /* pointer to next XMIT byte */
143 int xleft; /* bytes left in XMIT queue */
145 /* SLCAN interface statistics. */
146 struct net_device_stats stats;
148 unsigned long flags; /* Flag values/ mode etc */
149 #define SLF_INUSE 0 /* Channel in use */
150 #define SLF_ERROR 1 /* Parity, etc. error */
152 unsigned char leased;
157 static struct net_device **slcan_devs;
159 /************************************************************************
160 * SLCAN ENCAPSULATION FORMAT *
161 ************************************************************************/
164 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
165 * frame format) a data length code (can_dlc) which can be from 0 to 8
166 * and up to <can_dlc> data bytes as payload.
167 * Additionally a CAN frame may become a remote transmission frame if the
168 * RTR-bit is set. This causes another ECU to send a CAN frame with the
171 * The SLCAN ASCII representation of these different frame types is:
172 * <type> <id> <dlc> <data>*
174 * Extended frames (29 bit) are defined by capital characters in the type.
175 * RTR frames are defined as 'r' types - normal frames have 't' type:
176 * t => 11 bit data frame
177 * r => 11 bit RTR frame
178 * T => 29 bit data frame
179 * R => 29 bit RTR frame
181 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
182 * The <dlc> is a one byte ASCII number ('0' - '8')
183 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
187 * t1230 : can_id 0x123, can_dlc 0, no data
188 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
189 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
190 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
194 /************************************************************************
195 * STANDARD SLCAN DECAPSULATION *
196 ************************************************************************/
198 static int asc2nibble(char c) {
200 if ((c >= '0') && (c <= '9'))
203 if ((c >= 'A') && (c <= 'F'))
206 if ((c >= 'a') && (c <= 'f'))
209 return 16; /* error */
212 /* Send one completely decapsulated can_frame to the network layer */
213 static void slc_bump(struct slcan *sl)
218 char cmd = sl->rbuff[0];
220 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
223 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
224 dlc_pos = 4; /* dlc position tiiid */
226 dlc_pos = 9; /* dlc position Tiiiiiiiid */
228 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
231 cf.can_dlc = sl->rbuff[dlc_pos] & 0x0F; /* get can_dlc */
233 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
234 cf.can_id = simple_strtoul(sl->rbuff+1, NULL, 16);
236 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
237 cf.can_id |= CAN_EFF_FLAG;
239 if ((cmd | 0x20) == 'r') /* RTR frame */
240 cf.can_id |= CAN_RTR_FLAG;
242 *(u64 *) (&cf.data) = 0; /* clear payload */
244 for (i = 0, dlc_pos++; i < cf.can_dlc; i++){
246 if ((tmp = asc2nibble(sl->rbuff[dlc_pos++])) > 0x0F)
248 cf.data[i] = (tmp << 4);
249 if ((tmp = asc2nibble(sl->rbuff[dlc_pos++])) > 0x0F)
255 skb = dev_alloc_skb(sizeof(struct can_frame));
260 skb->protocol = htons(ETH_P_CAN);
261 memcpy(skb_put(skb, sizeof(struct can_frame)),
262 &cf, sizeof(struct can_frame));
265 sl->dev->last_rx = jiffies;
266 sl->stats.rx_packets++;
267 sl->stats.rx_bytes += cf.can_dlc;
270 /* parse tty input stream */
271 static void slcan_unesc(struct slcan *sl, unsigned char s)
273 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
274 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
280 if (!test_bit(SLF_ERROR, &sl->flags)) {
281 if (sl->rcount < SLC_MTU) {
282 sl->rbuff[sl->rcount++] = s;
285 sl->stats.rx_over_errors++;
286 set_bit(SLF_ERROR, &sl->flags);
292 /************************************************************************
293 * STANDARD SLCAN ENCAPSULATION *
294 ************************************************************************/
296 /* Encapsulate one can_frame and stuff into a TTY queue. */
297 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
302 if (cf->can_id & CAN_RTR_FLAG)
303 cmd = 'R'; /* becomes 'r' in standard frame format */
305 cmd = 'T'; /* becomes 't' in standard frame format */
307 if (cf->can_id & CAN_EFF_FLAG)
308 sprintf(sl->xbuff, "%c%08X%d", cmd,
309 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
311 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
312 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
314 idx = strlen(sl->xbuff);
316 for (i = 0; i < cf->can_dlc; i++)
317 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
319 DBG("ASCII frame = '%s'\n", sl->xbuff);
321 strcat(sl->xbuff, "\r"); /* add terminating character */
323 /* Order of next two lines is *very* important.
324 * When we are sending a little amount of data,
325 * the transfer may be completed inside driver.write()
326 * routine, because it's running with interrupts enabled.
327 * In this case we *never* got WRITE_WAKEUP event,
328 * if we did not request it before write operation.
329 * 14 Oct 1994 Dmitry Gorodchanin.
331 sl->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
332 actual = sl->tty->driver->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
333 #ifdef SLC_CHECK_TRANSMIT
334 sl->dev->trans_start = jiffies;
336 sl->xleft = strlen(sl->xbuff) - actual;
337 sl->xhead = sl->xbuff + actual;
338 sl->stats.tx_bytes += cf->can_dlc;
342 * Called by the driver when there's room for more data. If we have
343 * more packets to send, we send them here.
345 static void slcan_write_wakeup(struct tty_struct *tty)
348 struct slcan *sl = (struct slcan *) tty->disc_data;
350 /* First make sure we're connected. */
351 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
354 if (sl->xleft <= 0) {
355 /* Now serial buffer is almost free & we can start
356 * transmission of another packet */
357 sl->stats.tx_packets++;
358 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
359 netif_wake_queue(sl->dev);
363 actual = tty->driver->write(tty, sl->xhead, sl->xleft);
368 static void slc_tx_timeout(struct net_device *dev)
370 struct slcan *sl = netdev_priv(dev);
372 spin_lock(&sl->lock);
374 if (netif_queue_stopped(dev)) {
375 if (!netif_running(dev))
378 /* May be we must check transmitter timeout here ?
379 * 14 Oct 1994 Dmitry Gorodchanin.
381 #ifdef SLC_CHECK_TRANSMIT
382 if (time_before(jiffies, dev->trans_start + 20 * HZ)) {
383 /* 20 sec timeout not reached */
386 printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
387 (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft)
388 ? "bad line quality" : "driver error");
390 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
391 netif_wake_queue(sl->dev);
395 spin_unlock(&sl->lock);
399 /******************************************
400 * Routines looking at netdevice side.
401 ******************************************/
403 /* Send a can_frame to a TTY queue. */
404 static int slc_xmit(struct sk_buff *skb, struct net_device *dev)
406 struct slcan *sl = netdev_priv(dev);
408 if (skb->len != sizeof(struct can_frame))
411 spin_lock(&sl->lock);
412 if (!netif_running(dev)) {
413 spin_unlock(&sl->lock);
414 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
418 if (sl->tty == NULL) {
419 spin_unlock(&sl->lock);
423 netif_stop_queue(sl->dev);
424 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
425 spin_unlock(&sl->lock);
433 /* Netdevice UP -> DOWN routine */
434 static int slc_close(struct net_device *dev)
436 struct slcan *sl = netdev_priv(dev);
438 spin_lock_bh(&sl->lock);
440 /* TTY discipline is running. */
441 sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
443 netif_stop_queue(dev);
446 spin_unlock_bh(&sl->lock);
451 /* Netdevice DOWN -> UP routine */
452 static int slc_open(struct net_device *dev)
454 struct slcan *sl = netdev_priv(dev);
459 sl->flags &= (1 << SLF_INUSE);
460 netif_start_queue(dev);
464 /* Netdevice get statistics request */
465 static struct net_device_stats *slc_get_stats(struct net_device *dev)
467 struct slcan *sl = netdev_priv(dev);
472 /* Netdevice register callback */
473 static void slc_setup(struct net_device *dev)
475 dev->open = slc_open;
476 dev->destructor = free_netdev;
477 dev->stop = slc_close;
478 dev->get_stats = slc_get_stats;
479 dev->hard_start_xmit = slc_xmit;
481 dev->hard_header_len = 0;
483 dev->tx_queue_len = 10;
485 SET_MODULE_OWNER(dev);
487 dev->mtu = sizeof(struct can_frame);
488 dev->type = ARPHRD_CAN;
489 #ifdef SLC_CHECK_TRANSMIT
490 dev->tx_timeout = slc_tx_timeout;
491 dev->watchdog_timeo = 20*HZ;
494 /* New-style flags. */
495 dev->flags = IFF_NOARP;
496 dev->features = NETIF_F_NO_CSUM;
499 /******************************************
500 * Routines looking at TTY side.
501 ******************************************/
503 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
504 static int slcan_receive_room(struct tty_struct *tty)
506 return 65536; /* We can handle an infinite amount of data. :-) */
510 * Handle the 'receiver data ready' interrupt.
511 * This function is called by the 'tty_io' module in the kernel when
512 * a block of SLCAN data has been received, which can now be decapsulated
513 * and sent on to some IP layer for further processing. This will not
514 * be re-entered while running but other ldisc functions may be called
518 static void slcan_receive_buf(struct tty_struct *tty,
519 const unsigned char *cp, char *fp, int count)
521 struct slcan *sl = (struct slcan *) tty->disc_data;
523 if (!sl || sl->magic != SLCAN_MAGIC ||
524 !netif_running(sl->dev))
527 /* Read the characters out of the buffer */
530 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) {
531 sl->stats.rx_errors++;
536 slcan_unesc(sl, *cp++);
540 /************************************
541 * slcan_open helper routines.
542 ************************************/
544 /* Collect hanged up channels */
546 static void slc_sync(void)
549 struct net_device *dev;
552 for (i = 0; i < maxdev; i++) {
553 if ((dev = slcan_devs[i]) == NULL)
556 sl = netdev_priv(dev);
557 if (sl->tty || sl->leased)
559 if (dev->flags&IFF_UP)
565 /* Find a free SLCAN channel, and link in this `tty' line. */
566 static struct slcan *slc_alloc(dev_t line)
571 struct net_device *dev = NULL;
574 if (slcan_devs == NULL)
575 return NULL; /* Master array missing ! */
577 for (i = 0; i < maxdev; i++) {
582 sl = netdev_priv(dev);
584 if (sl->line != line)
589 /* Clear ESCAPE & ERROR flags */
590 sl->flags &= (1 << SLF_INUSE);
597 if (current->pid == sl->pid) {
598 if (sl->line == line && score < 3) {
609 if (sl->line == line && score < 1) {
624 sl = netdev_priv(dev);
625 sl->flags &= (1 << SLF_INUSE);
630 /* Sorry, too many, all slots in use */
635 sl = netdev_priv(dev);
636 if (test_bit(SLF_INUSE, &sl->flags)) {
637 unregister_netdevice(dev);
638 free_netdev(dev); /* new in slcan.c */
640 slcan_devs[i] = NULL;
646 sprintf(name, "slc%d", i);
648 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
654 sl = netdev_priv(dev);
656 /* Initialize channel control data */
657 sl->magic = SLCAN_MAGIC;
659 spin_lock_init(&sl->lock);
666 * Open the high-level part of the SLCAN channel.
667 * This function is called by the TTY module when the
668 * SLCAN line discipline is called for. Because we are
669 * sure the tty line exists, we only have to link it to
670 * a free SLCAN channel...
672 * Called in process context serialized from other ldisc calls.
675 static int slcan_open(struct tty_struct *tty)
680 if(!capable(CAP_NET_ADMIN))
683 /* RTnetlink lock is misused here to serialize concurrent
684 opens of slcan channels. There are better ways, but it is
689 /* Collect hanged up channels. */
692 sl = (struct slcan *) tty->disc_data;
695 /* First make sure we're not already connected. */
696 if (sl && sl->magic == SLCAN_MAGIC)
699 /* OK. Find a free SLCAN channel to use. */
701 if ((sl = slc_alloc(tty_devnum(tty))) == NULL)
706 sl->line = tty_devnum(tty);
707 sl->pid = current->pid;
709 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
710 /* FIXME: already done before we were called - seems this can go */
711 if (tty->driver->flush_buffer)
712 tty->driver->flush_buffer(tty);
714 if (!test_bit(SLF_INUSE, &sl->flags)) {
715 /* Perform the low-level SLCAN initialization. */
719 set_bit(SLF_INUSE, &sl->flags);
721 if ((err = register_netdevice(sl->dev)))
725 /* Done. We have linked the TTY line to a channel. */
727 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
728 tty->receive_room = 65536; /* We don't flow control */
730 return sl->dev->base_addr;
734 tty->disc_data = NULL;
735 clear_bit(SLF_INUSE, &sl->flags);
740 /* Count references from TTY module */
746 FIXME: 1,2 are fixed 3 was never true anyway.
748 Let me to blame a bit.
749 1. TTY module calls this funstion on soft interrupt.
750 2. TTY module calls this function WITH MASKED INTERRUPTS!
751 3. TTY module does not notify us about line discipline
754 Seems, now it is clean. The solution is to consider netdevice and
755 line discipline sides as two independent threads.
757 By-product (not desired): slc? does not feel hangups and remains open.
758 It is supposed, that user level program (dip, diald, slattach...)
759 will catch SIGHUP and make the rest of work.
761 I see no way to make more with current tty code. --ANK
765 * Close down a SLCAN channel.
766 * This means flushing out any pending queues, and then returning. This
767 * call is serialized against other ldisc functions.
769 static void slcan_close(struct tty_struct *tty)
771 struct slcan *sl = (struct slcan *) tty->disc_data;
773 /* First make sure we're connected. */
774 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
777 tty->disc_data = NULL;
782 /* Count references from TTY module */
785 /* Perform I/O control on an active SLCAN channel. */
786 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
787 unsigned int cmd, unsigned long arg)
789 struct slcan *sl = (struct slcan *) tty->disc_data;
792 /* First make sure we're connected. */
793 if (!sl || sl->magic != SLCAN_MAGIC) {
799 tmp = strlen(sl->dev->name) + 1;
800 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
808 /* Allow stty to read, but not set, the serial port */
811 return n_tty_ioctl(tty, file, cmd, arg);
818 static struct tty_ldisc slc_ldisc = {
819 .owner = THIS_MODULE,
820 .magic = TTY_LDISC_MAGIC,
823 .close = slcan_close,
824 .ioctl = slcan_ioctl,
825 .receive_buf = slcan_receive_buf,
826 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,16)
827 .receive_room = slcan_receive_room,
829 .write_wakeup = slcan_write_wakeup,
832 /************************************
833 * general slcan module init/exit
834 ************************************/
836 static int __init slcan_init(void)
841 maxdev = 4; /* Sanity */
844 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev );
846 slcan_devs = kmalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
848 printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
852 /* Clear the pointer array, we allocate devices when we need them */
853 memset(slcan_devs, 0, sizeof(struct net_device *)*maxdev);
855 /* Fill in our line protocol discipline, and register it */
856 if ((status = tty_register_ldisc(N_SLCAN, &slc_ldisc)) != 0) {
857 printk(KERN_ERR "slcan: can't register line discipline\n");
863 static void __exit slcan_exit(void)
866 struct net_device *dev;
868 unsigned long timeout = jiffies + HZ;
871 if (slcan_devs == NULL)
874 /* First of all: check for active disciplines and hangup them.
878 msleep_interruptible(100);
881 for (i = 0; i < maxdev; i++) {
885 sl = netdev_priv(dev);
886 spin_lock_bh(&sl->lock);
891 spin_unlock_bh(&sl->lock);
893 } while (busy && time_before(jiffies, timeout));
896 for (i = 0; i < maxdev; i++) {
900 slcan_devs[i] = NULL;
902 sl = netdev_priv(dev);
904 printk(KERN_ERR "%s: tty discipline still running\n",
906 /* Intentionally leak the control block. */
907 dev->destructor = NULL;
910 unregister_netdev(dev);
916 if ((i = tty_unregister_ldisc(N_SLCAN)))
918 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
922 module_init(slcan_init);
923 module_exit(slcan_exit);