2 * slcan.c - serial line CAN interface driver (using tty line discipline)
4 * This file is derived from linux/drivers/net/slip/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, see http://www.gnu.org/licenses/gpl.html
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
33 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
38 #include <linux/module.h>
39 #include <linux/moduleparam.h>
41 #include <linux/uaccess.h>
42 #include <linux/bitops.h>
43 #include <linux/string.h>
44 #include <linux/tty.h>
45 #include <linux/errno.h>
46 #include <linux/netdevice.h>
47 #include <linux/skbuff.h>
48 #include <linux/rtnetlink.h>
49 #include <linux/if_arp.h>
50 #include <linux/if_ether.h>
51 #include <linux/sched.h>
52 #include <linux/delay.h>
53 #include <linux/init.h>
54 #include <linux/kernel.h>
55 #include <linux/workqueue.h>
56 #include <linux/can.h>
57 #include <linux/can/skb.h>
59 MODULE_ALIAS_LDISC(N_SLCAN);
60 MODULE_DESCRIPTION("serial line CAN interface");
61 MODULE_LICENSE("GPL");
62 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
64 #define SLCAN_MAGIC 0x53CA
66 static int maxdev = 10; /* MAX number of SLCAN channels;
67 This can be overridden with
68 insmod slcan.ko maxdev=nnn */
69 module_param(maxdev, int, 0);
70 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
72 /* maximum rx buffer len: extended CAN frame with timestamp */
73 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
76 #define SLC_SFF_ID_LEN 3
77 #define SLC_EFF_ID_LEN 8
83 struct tty_struct *tty; /* ptr to TTY structure */
84 struct net_device *dev; /* easy for intr handling */
86 struct work_struct tx_work; /* Flushes transmit buffer */
88 /* These are pointers to the malloc()ed frame buffers. */
89 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
90 int rcount; /* received chars counter */
91 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
92 unsigned char *xhead; /* pointer to next XMIT byte */
93 int xleft; /* bytes left in XMIT queue */
95 unsigned long flags; /* Flag values/ mode etc */
96 #define SLF_INUSE 0 /* Channel in use */
97 #define SLF_ERROR 1 /* Parity, etc. error */
100 static struct net_device **slcan_devs;
102 /************************************************************************
103 * SLCAN ENCAPSULATION FORMAT *
104 ************************************************************************/
107 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
108 * frame format) a data length code (can_dlc) which can be from 0 to 8
109 * and up to <can_dlc> data bytes as payload.
110 * Additionally a CAN frame may become a remote transmission frame if the
111 * RTR-bit is set. This causes another ECU to send a CAN frame with the
114 * The SLCAN ASCII representation of these different frame types is:
115 * <type> <id> <dlc> <data>*
117 * Extended frames (29 bit) are defined by capital characters in the type.
118 * RTR frames are defined as 'r' types - normal frames have 't' type:
119 * t => 11 bit data frame
120 * r => 11 bit RTR frame
121 * T => 29 bit data frame
122 * R => 29 bit RTR frame
124 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
125 * The <dlc> is a one byte ASCII number ('0' - '8')
126 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
130 * t1230 : can_id 0x123, can_dlc 0, no data
131 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
132 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
133 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
137 /************************************************************************
138 * STANDARD SLCAN DECAPSULATION *
139 ************************************************************************/
141 /* Send one completely decapsulated can_frame to the network layer */
142 static void slc_bump(struct slcan *sl)
148 char *cmd = sl->rbuff;
150 memset(&cf, 0, sizeof(cf));
154 cf.can_id = CAN_RTR_FLAG;
157 /* store dlc ASCII value and terminate SFF CAN ID string */
158 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
159 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
160 /* point to payload data behind the dlc */
161 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
164 cf.can_id = CAN_RTR_FLAG;
167 cf.can_id |= CAN_EFF_FLAG;
168 /* store dlc ASCII value and terminate EFF CAN ID string */
169 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
170 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
171 /* point to payload data behind the dlc */
172 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
178 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
183 /* get can_dlc from sanitized ASCII value */
184 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
189 /* RTR frames may have a dlc > 0 but they never have any data bytes */
190 if (!(cf.can_id & CAN_RTR_FLAG)) {
191 for (i = 0; i < cf.can_dlc; i++) {
192 tmp = hex_to_bin(*cmd++);
195 cf.data[i] = (tmp << 4);
196 tmp = hex_to_bin(*cmd++);
203 skb = dev_alloc_skb(sizeof(struct can_frame) +
204 sizeof(struct can_skb_priv));
209 skb->protocol = htons(ETH_P_CAN);
210 skb->pkt_type = PACKET_BROADCAST;
211 skb->ip_summed = CHECKSUM_UNNECESSARY;
213 can_skb_reserve(skb);
214 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
215 can_skb_prv(skb)->skbcnt = 0;
217 memcpy(skb_put(skb, sizeof(struct can_frame)),
218 &cf, sizeof(struct can_frame));
220 sl->dev->stats.rx_packets++;
221 sl->dev->stats.rx_bytes += cf.can_dlc;
225 /* parse tty input stream */
226 static void slcan_unesc(struct slcan *sl, unsigned char s)
228 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
229 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
235 if (!test_bit(SLF_ERROR, &sl->flags)) {
236 if (sl->rcount < SLC_MTU) {
237 sl->rbuff[sl->rcount++] = s;
240 sl->dev->stats.rx_over_errors++;
241 set_bit(SLF_ERROR, &sl->flags);
247 /************************************************************************
248 * STANDARD SLCAN ENCAPSULATION *
249 ************************************************************************/
251 /* Encapsulate one can_frame and stuff into a TTY queue. */
252 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
256 unsigned char *endpos;
257 canid_t id = cf->can_id;
261 if (cf->can_id & CAN_RTR_FLAG)
262 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
264 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
266 /* determine number of chars for the CAN-identifier */
267 if (cf->can_id & CAN_EFF_FLAG) {
269 endpos = pos + SLC_EFF_ID_LEN;
271 *pos |= 0x20; /* convert R/T to lower case for SFF */
273 endpos = pos + SLC_SFF_ID_LEN;
276 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
278 while (endpos >= pos) {
279 *endpos-- = hex_asc_upper[id & 0xf];
283 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
285 *pos++ = cf->can_dlc + '0';
287 /* RTR frames may have a dlc > 0 but they never have any data bytes */
288 if (!(cf->can_id & CAN_RTR_FLAG)) {
289 for (i = 0; i < cf->can_dlc; i++)
290 pos = hex_byte_pack_upper(pos, cf->data[i]);
295 /* Order of next two lines is *very* important.
296 * When we are sending a little amount of data,
297 * the transfer may be completed inside the ops->write()
298 * routine, because it's running with interrupts enabled.
299 * In this case we *never* got WRITE_WAKEUP event,
300 * if we did not request it before write operation.
301 * 14 Oct 1994 Dmitry Gorodchanin.
303 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
304 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
305 sl->xleft = (pos - sl->xbuff) - actual;
306 sl->xhead = sl->xbuff + actual;
307 sl->dev->stats.tx_bytes += cf->can_dlc;
310 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
311 static void slcan_transmit(struct work_struct *work)
313 struct slcan *sl = container_of(work, struct slcan, tx_work);
316 spin_lock_bh(&sl->lock);
317 /* First make sure we're connected. */
318 if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
319 spin_unlock_bh(&sl->lock);
323 if (sl->xleft <= 0) {
324 /* Now serial buffer is almost free & we can start
325 * transmission of another packet */
326 sl->dev->stats.tx_packets++;
327 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
328 spin_unlock_bh(&sl->lock);
329 netif_wake_queue(sl->dev);
333 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
336 spin_unlock_bh(&sl->lock);
340 * Called by the driver when there's room for more data.
341 * Schedule the transmit.
343 static void slcan_write_wakeup(struct tty_struct *tty)
348 sl = rcu_dereference(tty->disc_data);
352 schedule_work(&sl->tx_work);
357 /* Send a can_frame to a TTY queue. */
358 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
360 struct slcan *sl = netdev_priv(dev);
362 if (skb->len != CAN_MTU)
365 spin_lock(&sl->lock);
366 if (!netif_running(dev)) {
367 spin_unlock(&sl->lock);
368 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
371 if (sl->tty == NULL) {
372 spin_unlock(&sl->lock);
376 netif_stop_queue(sl->dev);
377 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
378 spin_unlock(&sl->lock);
386 /******************************************
387 * Routines looking at netdevice side.
388 ******************************************/
390 /* Netdevice UP -> DOWN routine */
391 static int slc_close(struct net_device *dev)
393 struct slcan *sl = netdev_priv(dev);
395 spin_lock_bh(&sl->lock);
397 /* TTY discipline is running. */
398 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
400 netif_stop_queue(dev);
403 spin_unlock_bh(&sl->lock);
408 /* Netdevice DOWN -> UP routine */
409 static int slc_open(struct net_device *dev)
411 struct slcan *sl = netdev_priv(dev);
416 sl->flags &= (1 << SLF_INUSE);
417 netif_start_queue(dev);
421 /* Hook the destructor so we can free slcan devs at the right point in time */
422 static void slc_free_netdev(struct net_device *dev)
424 int i = dev->base_addr;
426 slcan_devs[i] = NULL;
429 static int slcan_change_mtu(struct net_device *dev, int new_mtu)
434 static const struct net_device_ops slc_netdev_ops = {
435 .ndo_open = slc_open,
436 .ndo_stop = slc_close,
437 .ndo_start_xmit = slc_xmit,
438 .ndo_change_mtu = slcan_change_mtu,
441 static void slc_setup(struct net_device *dev)
443 dev->netdev_ops = &slc_netdev_ops;
444 dev->destructor = slc_free_netdev;
446 dev->hard_header_len = 0;
448 dev->tx_queue_len = 10;
451 dev->type = ARPHRD_CAN;
453 /* New-style flags. */
454 dev->flags = IFF_NOARP;
455 dev->features = NETIF_F_HW_CSUM;
458 /******************************************
459 Routines looking at TTY side.
460 ******************************************/
463 * Handle the 'receiver data ready' interrupt.
464 * This function is called by the 'tty_io' module in the kernel when
465 * a block of SLCAN data has been received, which can now be decapsulated
466 * and sent on to some IP layer for further processing. This will not
467 * be re-entered while running but other ldisc functions may be called
471 static void slcan_receive_buf(struct tty_struct *tty,
472 const unsigned char *cp, char *fp, int count)
474 struct slcan *sl = (struct slcan *) tty->disc_data;
476 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
479 /* Read the characters out of the buffer */
482 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
483 sl->dev->stats.rx_errors++;
487 slcan_unesc(sl, *cp++);
491 /************************************
492 * slcan_open helper routines.
493 ************************************/
495 /* Collect hanged up channels */
496 static void slc_sync(void)
499 struct net_device *dev;
502 for (i = 0; i < maxdev; i++) {
507 sl = netdev_priv(dev);
510 if (dev->flags & IFF_UP)
515 /* Find a free SLCAN channel, and link in this `tty' line. */
516 static struct slcan *slc_alloc(dev_t line)
520 struct net_device *dev = NULL;
523 for (i = 0; i < maxdev; i++) {
530 /* Sorry, too many, all slots in use */
534 sprintf(name, "slcan%d", i);
535 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, slc_setup);
540 sl = netdev_priv(dev);
542 /* Initialize channel control data */
543 sl->magic = SLCAN_MAGIC;
545 spin_lock_init(&sl->lock);
546 INIT_WORK(&sl->tx_work, slcan_transmit);
553 * Open the high-level part of the SLCAN channel.
554 * This function is called by the TTY module when the
555 * SLCAN line discipline is called for. Because we are
556 * sure the tty line exists, we only have to link it to
557 * a free SLCAN channel...
559 * Called in process context serialized from other ldisc calls.
562 static int slcan_open(struct tty_struct *tty)
567 if (!capable(CAP_NET_ADMIN))
570 if (tty->ops->write == NULL)
573 /* RTnetlink lock is misused here to serialize concurrent
574 opens of slcan channels. There are better ways, but it is
579 /* Collect hanged up channels. */
585 /* First make sure we're not already connected. */
586 if (sl && sl->magic == SLCAN_MAGIC)
589 /* OK. Find a free SLCAN channel to use. */
591 sl = slc_alloc(tty_devnum(tty));
598 if (!test_bit(SLF_INUSE, &sl->flags)) {
599 /* Perform the low-level SLCAN initialization. */
603 set_bit(SLF_INUSE, &sl->flags);
605 err = register_netdevice(sl->dev);
610 /* Done. We have linked the TTY line to a channel. */
612 tty->receive_room = 65536; /* We don't flow control */
614 /* TTY layer expects 0 on success */
619 tty->disc_data = NULL;
620 clear_bit(SLF_INUSE, &sl->flags);
621 /* do not call free_netdev before rtnl_unlock */
623 slc_free_netdev(sl->dev);
629 /* Count references from TTY module */
634 * Close down a SLCAN channel.
635 * This means flushing out any pending queues, and then returning. This
636 * call is serialized against other ldisc functions.
638 * We also use this method for a hangup event.
641 static void slcan_close(struct tty_struct *tty)
643 struct slcan *sl = (struct slcan *) tty->disc_data;
645 /* First make sure we're connected. */
646 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
649 spin_lock_bh(&sl->lock);
650 rcu_assign_pointer(tty->disc_data, NULL);
652 spin_unlock_bh(&sl->lock);
655 flush_work(&sl->tx_work);
657 /* Flush network side */
658 unregister_netdev(sl->dev);
659 /* This will complete via sl_free_netdev */
662 static int slcan_hangup(struct tty_struct *tty)
668 /* Perform I/O control on an active SLCAN channel. */
669 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
670 unsigned int cmd, unsigned long arg)
672 struct slcan *sl = (struct slcan *) tty->disc_data;
675 /* First make sure we're connected. */
676 if (!sl || sl->magic != SLCAN_MAGIC)
681 tmp = strlen(sl->dev->name) + 1;
682 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
690 return tty_mode_ioctl(tty, file, cmd, arg);
694 static struct tty_ldisc_ops slc_ldisc = {
695 .owner = THIS_MODULE,
696 .magic = TTY_LDISC_MAGIC,
699 .close = slcan_close,
700 .hangup = slcan_hangup,
701 .ioctl = slcan_ioctl,
702 .receive_buf = slcan_receive_buf,
703 .write_wakeup = slcan_write_wakeup,
706 static int __init slcan_init(void)
711 maxdev = 4; /* Sanity */
713 pr_info("slcan: serial line CAN interface driver\n");
714 pr_info("slcan: %d dynamic interface channels.\n", maxdev);
716 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
720 /* Fill in our line protocol discipline, and register it */
721 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
723 printk(KERN_ERR "slcan: can't register line discipline\n");
729 static void __exit slcan_exit(void)
732 struct net_device *dev;
734 unsigned long timeout = jiffies + HZ;
737 if (slcan_devs == NULL)
740 /* First of all: check for active disciplines and hangup them.
744 msleep_interruptible(100);
747 for (i = 0; i < maxdev; i++) {
751 sl = netdev_priv(dev);
752 spin_lock_bh(&sl->lock);
757 spin_unlock_bh(&sl->lock);
759 } while (busy && time_before(jiffies, timeout));
761 /* FIXME: hangup is async so we should wait when doing this second
764 for (i = 0; i < maxdev; i++) {
768 slcan_devs[i] = NULL;
770 sl = netdev_priv(dev);
772 printk(KERN_ERR "%s: tty discipline still running\n",
774 /* Intentionally leak the control block. */
775 dev->destructor = NULL;
778 unregister_netdev(dev);
784 i = tty_unregister_ldisc(N_SLCAN);
786 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
789 module_init(slcan_init);
790 module_exit(slcan_exit);