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, 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
40 #include <linux/module.h>
41 #include <linux/moduleparam.h>
43 #include <linux/uaccess.h>
44 #include <linux/bitops.h>
45 #include <linux/string.h>
46 #include <linux/tty.h>
47 #include <linux/errno.h>
48 #include <linux/netdevice.h>
49 #include <linux/skbuff.h>
50 #include <linux/rtnetlink.h>
51 #include <linux/if_arp.h>
52 #include <linux/if_ether.h>
53 #include <linux/sched.h>
54 #include <linux/delay.h>
55 #include <linux/init.h>
56 #include <linux/kernel.h>
57 #include <linux/can.h>
58 #include <linux/can/skb.h>
60 static __initconst const char banner[] =
61 KERN_INFO "slcan: serial line CAN interface driver\n";
63 MODULE_ALIAS_LDISC(N_SLCAN);
64 MODULE_DESCRIPTION("serial line CAN interface");
65 MODULE_LICENSE("GPL");
66 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
68 #define SLCAN_MAGIC 0x53CA
70 static int maxdev = 10; /* MAX number of SLCAN channels;
71 This can be overridden with
72 insmod slcan.ko maxdev=nnn */
73 module_param(maxdev, int, 0);
74 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
76 /* maximum rx buffer len: extended CAN frame with timestamp */
77 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
80 #define SLC_SFF_ID_LEN 3
81 #define SLC_EFF_ID_LEN 8
87 struct tty_struct *tty; /* ptr to TTY structure */
88 struct net_device *dev; /* easy for intr handling */
91 /* These are pointers to the malloc()ed frame buffers. */
92 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
93 int rcount; /* received chars counter */
94 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
95 unsigned char *xhead; /* pointer to next XMIT byte */
96 int xleft; /* bytes left in XMIT queue */
98 unsigned long flags; /* Flag values/ mode etc */
99 #define SLF_INUSE 0 /* Channel in use */
100 #define SLF_ERROR 1 /* Parity, etc. error */
103 static struct net_device **slcan_devs;
105 /************************************************************************
106 * SLCAN ENCAPSULATION FORMAT *
107 ************************************************************************/
110 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
111 * frame format) a data length code (can_dlc) which can be from 0 to 8
112 * and up to <can_dlc> data bytes as payload.
113 * Additionally a CAN frame may become a remote transmission frame if the
114 * RTR-bit is set. This causes another ECU to send a CAN frame with the
117 * The SLCAN ASCII representation of these different frame types is:
118 * <type> <id> <dlc> <data>*
120 * Extended frames (29 bit) are defined by capital characters in the type.
121 * RTR frames are defined as 'r' types - normal frames have 't' type:
122 * t => 11 bit data frame
123 * r => 11 bit RTR frame
124 * T => 29 bit data frame
125 * R => 29 bit RTR frame
127 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
128 * The <dlc> is a one byte ASCII number ('0' - '8')
129 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
133 * t1230 : can_id 0x123, can_dlc 0, no data
134 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
135 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
136 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
140 /************************************************************************
141 * STANDARD SLCAN DECAPSULATION *
142 ************************************************************************/
144 /* Send one completely decapsulated can_frame to the network layer */
145 static void slc_bump(struct slcan *sl)
151 char *cmd = sl->rbuff;
157 cf.can_id = CAN_RTR_FLAG;
160 /* store dlc ASCII value and terminate SFF CAN ID string */
161 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
162 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
163 /* point to payload data behind the dlc */
164 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
167 cf.can_id = CAN_RTR_FLAG;
170 cf.can_id |= CAN_EFF_FLAG;
171 /* store dlc ASCII value and terminate EFF CAN ID string */
172 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
173 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
174 /* point to payload data behind the dlc */
175 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
181 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
186 /* get can_dlc from sanitized ASCII value */
187 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
192 *(u64 *) (&cf.data) = 0; /* clear payload */
194 /* RTR frames may have a dlc > 0 but they never have any data bytes */
195 if (!(cf.can_id & CAN_RTR_FLAG)) {
196 for (i = 0; i < cf.can_dlc; i++) {
197 tmp = hex_to_bin(*cmd++);
200 cf.data[i] = (tmp << 4);
201 tmp = hex_to_bin(*cmd++);
208 skb = dev_alloc_skb(sizeof(struct can_frame) +
209 sizeof(struct can_skb_priv));
214 skb->protocol = htons(ETH_P_CAN);
215 skb->pkt_type = PACKET_BROADCAST;
216 skb->ip_summed = CHECKSUM_UNNECESSARY;
218 can_skb_reserve(skb);
219 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
221 memcpy(skb_put(skb, sizeof(struct can_frame)),
222 &cf, sizeof(struct can_frame));
225 sl->dev->stats.rx_packets++;
226 sl->dev->stats.rx_bytes += cf.can_dlc;
229 /* parse tty input stream */
230 static void slcan_unesc(struct slcan *sl, unsigned char s)
232 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
233 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
239 if (!test_bit(SLF_ERROR, &sl->flags)) {
240 if (sl->rcount < SLC_MTU) {
241 sl->rbuff[sl->rcount++] = s;
244 sl->dev->stats.rx_over_errors++;
245 set_bit(SLF_ERROR, &sl->flags);
251 /************************************************************************
252 * STANDARD SLCAN ENCAPSULATION *
253 ************************************************************************/
255 /* Encapsulate one can_frame and stuff into a TTY queue. */
256 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
260 unsigned char *endpos;
261 canid_t id = cf->can_id;
265 if (cf->can_id & CAN_RTR_FLAG)
266 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
268 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
270 /* determine number of chars for the CAN-identifier */
271 if (cf->can_id & CAN_EFF_FLAG) {
273 endpos = pos + SLC_EFF_ID_LEN;
275 *pos |= 0x20; /* convert R/T to lower case for SFF */
277 endpos = pos + SLC_SFF_ID_LEN;
280 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
282 while (endpos >= pos) {
283 *endpos-- = hex_asc_upper[id & 0xf];
287 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
289 *pos++ = cf->can_dlc + '0';
291 /* RTR frames may have a dlc > 0 but they never have any data bytes */
292 if (!(cf->can_id & CAN_RTR_FLAG)) {
293 for (i = 0; i < cf->can_dlc; i++)
294 pos = hex_byte_pack_upper(pos, cf->data[i]);
299 /* Order of next two lines is *very* important.
300 * When we are sending a little amount of data,
301 * the transfer may be completed inside the ops->write()
302 * routine, because it's running with interrupts enabled.
303 * In this case we *never* got WRITE_WAKEUP event,
304 * if we did not request it before write operation.
305 * 14 Oct 1994 Dmitry Gorodchanin.
307 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
308 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
309 sl->xleft = (pos - sl->xbuff) - actual;
310 sl->xhead = sl->xbuff + actual;
311 sl->dev->stats.tx_bytes += cf->can_dlc;
315 * Called by the driver when there's room for more data. If we have
316 * more packets to send, we send them here.
318 static void slcan_write_wakeup(struct tty_struct *tty)
321 struct slcan *sl = (struct slcan *) tty->disc_data;
323 /* First make sure we're connected. */
324 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
327 spin_lock(&sl->lock);
328 if (sl->xleft <= 0) {
329 /* Now serial buffer is almost free & we can start
330 * transmission of another packet */
331 sl->dev->stats.tx_packets++;
332 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
333 spin_unlock(&sl->lock);
334 netif_wake_queue(sl->dev);
338 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
341 spin_unlock(&sl->lock);
344 /* Send a can_frame to a TTY queue. */
345 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
347 struct slcan *sl = netdev_priv(dev);
349 if (skb->len != sizeof(struct can_frame))
352 spin_lock(&sl->lock);
353 if (!netif_running(dev)) {
354 spin_unlock(&sl->lock);
355 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
358 if (sl->tty == NULL) {
359 spin_unlock(&sl->lock);
363 netif_stop_queue(sl->dev);
364 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
365 spin_unlock(&sl->lock);
373 /******************************************
374 * Routines looking at netdevice side.
375 ******************************************/
377 /* Netdevice UP -> DOWN routine */
378 static int slc_close(struct net_device *dev)
380 struct slcan *sl = netdev_priv(dev);
382 spin_lock_bh(&sl->lock);
384 /* TTY discipline is running. */
385 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
387 netif_stop_queue(dev);
390 spin_unlock_bh(&sl->lock);
395 /* Netdevice DOWN -> UP routine */
396 static int slc_open(struct net_device *dev)
398 struct slcan *sl = netdev_priv(dev);
403 sl->flags &= (1 << SLF_INUSE);
404 netif_start_queue(dev);
408 /* Hook the destructor so we can free slcan devs at the right point in time */
409 static void slc_free_netdev(struct net_device *dev)
411 int i = dev->base_addr;
413 slcan_devs[i] = NULL;
416 static const struct net_device_ops slc_netdev_ops = {
417 .ndo_open = slc_open,
418 .ndo_stop = slc_close,
419 .ndo_start_xmit = slc_xmit,
422 static void slc_setup(struct net_device *dev)
424 dev->netdev_ops = &slc_netdev_ops;
425 dev->destructor = slc_free_netdev;
427 dev->hard_header_len = 0;
429 dev->tx_queue_len = 10;
431 dev->mtu = sizeof(struct can_frame);
432 dev->type = ARPHRD_CAN;
434 /* New-style flags. */
435 dev->flags = IFF_NOARP;
436 dev->features = NETIF_F_HW_CSUM;
439 /******************************************
440 Routines looking at TTY side.
441 ******************************************/
444 * Handle the 'receiver data ready' interrupt.
445 * This function is called by the 'tty_io' module in the kernel when
446 * a block of SLCAN data has been received, which can now be decapsulated
447 * and sent on to some IP layer for further processing. This will not
448 * be re-entered while running but other ldisc functions may be called
452 static void slcan_receive_buf(struct tty_struct *tty,
453 const unsigned char *cp, char *fp, int count)
455 struct slcan *sl = (struct slcan *) tty->disc_data;
457 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
460 /* Read the characters out of the buffer */
463 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
464 sl->dev->stats.rx_errors++;
468 slcan_unesc(sl, *cp++);
472 /************************************
473 * slcan_open helper routines.
474 ************************************/
476 /* Collect hanged up channels */
477 static void slc_sync(void)
480 struct net_device *dev;
483 for (i = 0; i < maxdev; i++) {
488 sl = netdev_priv(dev);
491 if (dev->flags & IFF_UP)
496 /* Find a free SLCAN channel, and link in this `tty' line. */
497 static struct slcan *slc_alloc(dev_t line)
501 struct net_device *dev = NULL;
504 for (i = 0; i < maxdev; i++) {
511 /* Sorry, too many, all slots in use */
515 sprintf(name, "slcan%d", i);
516 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
521 sl = netdev_priv(dev);
523 /* Initialize channel control data */
524 sl->magic = SLCAN_MAGIC;
526 spin_lock_init(&sl->lock);
533 * Open the high-level part of the SLCAN channel.
534 * This function is called by the TTY module when the
535 * SLCAN line discipline is called for. Because we are
536 * sure the tty line exists, we only have to link it to
537 * a free SLCAN channel...
539 * Called in process context serialized from other ldisc calls.
542 static int slcan_open(struct tty_struct *tty)
547 if (!capable(CAP_NET_ADMIN))
550 if (tty->ops->write == NULL)
553 /* RTnetlink lock is misused here to serialize concurrent
554 opens of slcan channels. There are better ways, but it is
559 /* Collect hanged up channels. */
565 /* First make sure we're not already connected. */
566 if (sl && sl->magic == SLCAN_MAGIC)
569 /* OK. Find a free SLCAN channel to use. */
571 sl = slc_alloc(tty_devnum(tty));
578 if (!test_bit(SLF_INUSE, &sl->flags)) {
579 /* Perform the low-level SLCAN initialization. */
583 set_bit(SLF_INUSE, &sl->flags);
585 err = register_netdevice(sl->dev);
590 /* Done. We have linked the TTY line to a channel. */
592 tty->receive_room = 65536; /* We don't flow control */
594 /* TTY layer expects 0 on success */
599 tty->disc_data = NULL;
600 clear_bit(SLF_INUSE, &sl->flags);
605 /* Count references from TTY module */
610 * Close down a SLCAN channel.
611 * This means flushing out any pending queues, and then returning. This
612 * call is serialized against other ldisc functions.
614 * We also use this method for a hangup event.
617 static void slcan_close(struct tty_struct *tty)
619 struct slcan *sl = (struct slcan *) tty->disc_data;
621 /* First make sure we're connected. */
622 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
625 tty->disc_data = NULL;
628 /* Flush network side */
629 unregister_netdev(sl->dev);
630 /* This will complete via sl_free_netdev */
633 static int slcan_hangup(struct tty_struct *tty)
639 /* Perform I/O control on an active SLCAN channel. */
640 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
641 unsigned int cmd, unsigned long arg)
643 struct slcan *sl = (struct slcan *) tty->disc_data;
646 /* First make sure we're connected. */
647 if (!sl || sl->magic != SLCAN_MAGIC)
652 tmp = strlen(sl->dev->name) + 1;
653 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
661 return tty_mode_ioctl(tty, file, cmd, arg);
665 static struct tty_ldisc_ops slc_ldisc = {
666 .owner = THIS_MODULE,
667 .magic = TTY_LDISC_MAGIC,
670 .close = slcan_close,
671 .hangup = slcan_hangup,
672 .ioctl = slcan_ioctl,
673 .receive_buf = slcan_receive_buf,
674 .write_wakeup = slcan_write_wakeup,
677 static int __init slcan_init(void)
682 maxdev = 4; /* Sanity */
685 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
687 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
691 /* Fill in our line protocol discipline, and register it */
692 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
694 printk(KERN_ERR "slcan: can't register line discipline\n");
700 static void __exit slcan_exit(void)
703 struct net_device *dev;
705 unsigned long timeout = jiffies + HZ;
708 if (slcan_devs == NULL)
711 /* First of all: check for active disciplines and hangup them.
715 msleep_interruptible(100);
718 for (i = 0; i < maxdev; i++) {
722 sl = netdev_priv(dev);
723 spin_lock_bh(&sl->lock);
728 spin_unlock_bh(&sl->lock);
730 } while (busy && time_before(jiffies, timeout));
732 /* FIXME: hangup is async so we should wait when doing this second
735 for (i = 0; i < maxdev; i++) {
739 slcan_devs[i] = NULL;
741 sl = netdev_priv(dev);
743 printk(KERN_ERR "%s: tty discipline still running\n",
745 /* Intentionally leak the control block. */
746 dev->destructor = NULL;
749 unregister_netdev(dev);
755 i = tty_unregister_ldisc(N_SLCAN);
757 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
760 module_init(slcan_init);
761 module_exit(slcan_exit);