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/can.h>
56 #include <linux/can/skb.h>
58 static __initconst const char banner[] =
59 KERN_INFO "slcan: serial line CAN interface driver\n";
61 MODULE_ALIAS_LDISC(N_SLCAN);
62 MODULE_DESCRIPTION("serial line CAN interface");
63 MODULE_LICENSE("GPL");
64 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
66 #define SLCAN_MAGIC 0x53CA
68 static int maxdev = 10; /* MAX number of SLCAN channels;
69 This can be overridden with
70 insmod slcan.ko maxdev=nnn */
71 module_param(maxdev, int, 0);
72 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
74 /* maximum rx buffer len: extended CAN frame with timestamp */
75 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
78 #define SLC_SFF_ID_LEN 3
79 #define SLC_EFF_ID_LEN 8
85 struct tty_struct *tty; /* ptr to TTY structure */
86 struct net_device *dev; /* easy for intr handling */
89 /* These are pointers to the malloc()ed frame buffers. */
90 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
91 int rcount; /* received chars counter */
92 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
93 unsigned char *xhead; /* pointer to next XMIT byte */
94 int xleft; /* bytes left in XMIT queue */
96 unsigned long flags; /* Flag values/ mode etc */
97 #define SLF_INUSE 0 /* Channel in use */
98 #define SLF_ERROR 1 /* Parity, etc. error */
101 static struct net_device **slcan_devs;
103 /************************************************************************
104 * SLCAN ENCAPSULATION FORMAT *
105 ************************************************************************/
108 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
109 * frame format) a data length code (can_dlc) which can be from 0 to 8
110 * and up to <can_dlc> data bytes as payload.
111 * Additionally a CAN frame may become a remote transmission frame if the
112 * RTR-bit is set. This causes another ECU to send a CAN frame with the
115 * The SLCAN ASCII representation of these different frame types is:
116 * <type> <id> <dlc> <data>*
118 * Extended frames (29 bit) are defined by capital characters in the type.
119 * RTR frames are defined as 'r' types - normal frames have 't' type:
120 * t => 11 bit data frame
121 * r => 11 bit RTR frame
122 * T => 29 bit data frame
123 * R => 29 bit RTR frame
125 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
126 * The <dlc> is a one byte ASCII number ('0' - '8')
127 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
131 * t1230 : can_id 0x123, can_dlc 0, no data
132 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
133 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
134 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
138 /************************************************************************
139 * STANDARD SLCAN DECAPSULATION *
140 ************************************************************************/
142 /* Send one completely decapsulated can_frame to the network layer */
143 static void slc_bump(struct slcan *sl)
149 char *cmd = sl->rbuff;
155 cf.can_id = CAN_RTR_FLAG;
158 /* store dlc ASCII value and terminate SFF CAN ID string */
159 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
160 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
161 /* point to payload data behind the dlc */
162 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
165 cf.can_id = CAN_RTR_FLAG;
168 cf.can_id |= CAN_EFF_FLAG;
169 /* store dlc ASCII value and terminate EFF CAN ID string */
170 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
171 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
172 /* point to payload data behind the dlc */
173 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
179 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
184 /* get can_dlc from sanitized ASCII value */
185 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
190 *(u64 *) (&cf.data) = 0; /* clear payload */
192 /* RTR frames may have a dlc > 0 but they never have any data bytes */
193 if (!(cf.can_id & CAN_RTR_FLAG)) {
194 for (i = 0; i < cf.can_dlc; i++) {
195 tmp = hex_to_bin(*cmd++);
198 cf.data[i] = (tmp << 4);
199 tmp = hex_to_bin(*cmd++);
206 skb = dev_alloc_skb(sizeof(struct can_frame) +
207 sizeof(struct can_skb_priv));
212 skb->protocol = htons(ETH_P_CAN);
213 skb->pkt_type = PACKET_BROADCAST;
214 skb->ip_summed = CHECKSUM_UNNECESSARY;
216 can_skb_reserve(skb);
217 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
219 memcpy(skb_put(skb, sizeof(struct can_frame)),
220 &cf, sizeof(struct can_frame));
223 sl->dev->stats.rx_packets++;
224 sl->dev->stats.rx_bytes += cf.can_dlc;
227 /* parse tty input stream */
228 static void slcan_unesc(struct slcan *sl, unsigned char s)
230 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
231 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
237 if (!test_bit(SLF_ERROR, &sl->flags)) {
238 if (sl->rcount < SLC_MTU) {
239 sl->rbuff[sl->rcount++] = s;
242 sl->dev->stats.rx_over_errors++;
243 set_bit(SLF_ERROR, &sl->flags);
249 /************************************************************************
250 * STANDARD SLCAN ENCAPSULATION *
251 ************************************************************************/
253 /* Encapsulate one can_frame and stuff into a TTY queue. */
254 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
258 unsigned char *endpos;
259 canid_t id = cf->can_id;
263 if (cf->can_id & CAN_RTR_FLAG)
264 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
266 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
268 /* determine number of chars for the CAN-identifier */
269 if (cf->can_id & CAN_EFF_FLAG) {
271 endpos = pos + SLC_EFF_ID_LEN;
273 *pos |= 0x20; /* convert R/T to lower case for SFF */
275 endpos = pos + SLC_SFF_ID_LEN;
278 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
280 while (endpos >= pos) {
281 *endpos-- = hex_asc_upper[id & 0xf];
285 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
287 *pos++ = cf->can_dlc + '0';
289 /* RTR frames may have a dlc > 0 but they never have any data bytes */
290 if (!(cf->can_id & CAN_RTR_FLAG)) {
291 for (i = 0; i < cf->can_dlc; i++)
292 pos = hex_byte_pack_upper(pos, cf->data[i]);
297 /* Order of next two lines is *very* important.
298 * When we are sending a little amount of data,
299 * the transfer may be completed inside the ops->write()
300 * routine, because it's running with interrupts enabled.
301 * In this case we *never* got WRITE_WAKEUP event,
302 * if we did not request it before write operation.
303 * 14 Oct 1994 Dmitry Gorodchanin.
305 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
306 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
307 sl->xleft = (pos - sl->xbuff) - actual;
308 sl->xhead = sl->xbuff + actual;
309 sl->dev->stats.tx_bytes += cf->can_dlc;
313 * Called by the driver when there's room for more data. If we have
314 * more packets to send, we send them here.
316 static void slcan_write_wakeup(struct tty_struct *tty)
319 struct slcan *sl = (struct slcan *) tty->disc_data;
321 /* First make sure we're connected. */
322 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
325 spin_lock(&sl->lock);
326 if (sl->xleft <= 0) {
327 /* Now serial buffer is almost free & we can start
328 * transmission of another packet */
329 sl->dev->stats.tx_packets++;
330 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
331 spin_unlock(&sl->lock);
332 netif_wake_queue(sl->dev);
336 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
339 spin_unlock(&sl->lock);
342 /* Send a can_frame to a TTY queue. */
343 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
345 struct slcan *sl = netdev_priv(dev);
347 if (skb->len != sizeof(struct can_frame))
350 spin_lock(&sl->lock);
351 if (!netif_running(dev)) {
352 spin_unlock(&sl->lock);
353 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
356 if (sl->tty == NULL) {
357 spin_unlock(&sl->lock);
361 netif_stop_queue(sl->dev);
362 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
363 spin_unlock(&sl->lock);
371 /******************************************
372 * Routines looking at netdevice side.
373 ******************************************/
375 /* Netdevice UP -> DOWN routine */
376 static int slc_close(struct net_device *dev)
378 struct slcan *sl = netdev_priv(dev);
380 spin_lock_bh(&sl->lock);
382 /* TTY discipline is running. */
383 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
385 netif_stop_queue(dev);
388 spin_unlock_bh(&sl->lock);
393 /* Netdevice DOWN -> UP routine */
394 static int slc_open(struct net_device *dev)
396 struct slcan *sl = netdev_priv(dev);
401 sl->flags &= (1 << SLF_INUSE);
402 netif_start_queue(dev);
406 /* Hook the destructor so we can free slcan devs at the right point in time */
407 static void slc_free_netdev(struct net_device *dev)
409 int i = dev->base_addr;
411 slcan_devs[i] = NULL;
414 static int slcan_change_mtu(struct net_device *dev, int new_mtu)
419 static const struct net_device_ops slc_netdev_ops = {
420 .ndo_open = slc_open,
421 .ndo_stop = slc_close,
422 .ndo_start_xmit = slc_xmit,
423 .ndo_change_mtu = slcan_change_mtu,
426 static void slc_setup(struct net_device *dev)
428 dev->netdev_ops = &slc_netdev_ops;
429 dev->destructor = slc_free_netdev;
431 dev->hard_header_len = 0;
433 dev->tx_queue_len = 10;
435 dev->mtu = sizeof(struct can_frame);
436 dev->type = ARPHRD_CAN;
438 /* New-style flags. */
439 dev->flags = IFF_NOARP;
440 dev->features = NETIF_F_HW_CSUM;
443 /******************************************
444 Routines looking at TTY side.
445 ******************************************/
448 * Handle the 'receiver data ready' interrupt.
449 * This function is called by the 'tty_io' module in the kernel when
450 * a block of SLCAN data has been received, which can now be decapsulated
451 * and sent on to some IP layer for further processing. This will not
452 * be re-entered while running but other ldisc functions may be called
456 static void slcan_receive_buf(struct tty_struct *tty,
457 const unsigned char *cp, char *fp, int count)
459 struct slcan *sl = (struct slcan *) tty->disc_data;
461 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
464 /* Read the characters out of the buffer */
467 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
468 sl->dev->stats.rx_errors++;
472 slcan_unesc(sl, *cp++);
476 /************************************
477 * slcan_open helper routines.
478 ************************************/
480 /* Collect hanged up channels */
481 static void slc_sync(void)
484 struct net_device *dev;
487 for (i = 0; i < maxdev; i++) {
492 sl = netdev_priv(dev);
495 if (dev->flags & IFF_UP)
500 /* Find a free SLCAN channel, and link in this `tty' line. */
501 static struct slcan *slc_alloc(dev_t line)
505 struct net_device *dev = NULL;
508 for (i = 0; i < maxdev; i++) {
515 /* Sorry, too many, all slots in use */
519 sprintf(name, "slcan%d", i);
520 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
525 sl = netdev_priv(dev);
527 /* Initialize channel control data */
528 sl->magic = SLCAN_MAGIC;
530 spin_lock_init(&sl->lock);
537 * Open the high-level part of the SLCAN channel.
538 * This function is called by the TTY module when the
539 * SLCAN line discipline is called for. Because we are
540 * sure the tty line exists, we only have to link it to
541 * a free SLCAN channel...
543 * Called in process context serialized from other ldisc calls.
546 static int slcan_open(struct tty_struct *tty)
551 if (!capable(CAP_NET_ADMIN))
554 if (tty->ops->write == NULL)
557 /* RTnetlink lock is misused here to serialize concurrent
558 opens of slcan channels. There are better ways, but it is
563 /* Collect hanged up channels. */
569 /* First make sure we're not already connected. */
570 if (sl && sl->magic == SLCAN_MAGIC)
573 /* OK. Find a free SLCAN channel to use. */
575 sl = slc_alloc(tty_devnum(tty));
582 if (!test_bit(SLF_INUSE, &sl->flags)) {
583 /* Perform the low-level SLCAN initialization. */
587 set_bit(SLF_INUSE, &sl->flags);
589 err = register_netdevice(sl->dev);
594 /* Done. We have linked the TTY line to a channel. */
596 tty->receive_room = 65536; /* We don't flow control */
598 /* TTY layer expects 0 on success */
603 tty->disc_data = NULL;
604 clear_bit(SLF_INUSE, &sl->flags);
609 /* Count references from TTY module */
614 * Close down a SLCAN channel.
615 * This means flushing out any pending queues, and then returning. This
616 * call is serialized against other ldisc functions.
618 * We also use this method for a hangup event.
621 static void slcan_close(struct tty_struct *tty)
623 struct slcan *sl = (struct slcan *) tty->disc_data;
625 /* First make sure we're connected. */
626 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
629 tty->disc_data = NULL;
632 /* Flush network side */
633 unregister_netdev(sl->dev);
634 /* This will complete via sl_free_netdev */
637 static int slcan_hangup(struct tty_struct *tty)
643 /* Perform I/O control on an active SLCAN channel. */
644 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
645 unsigned int cmd, unsigned long arg)
647 struct slcan *sl = (struct slcan *) tty->disc_data;
650 /* First make sure we're connected. */
651 if (!sl || sl->magic != SLCAN_MAGIC)
656 tmp = strlen(sl->dev->name) + 1;
657 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
665 return tty_mode_ioctl(tty, file, cmd, arg);
669 static struct tty_ldisc_ops slc_ldisc = {
670 .owner = THIS_MODULE,
671 .magic = TTY_LDISC_MAGIC,
674 .close = slcan_close,
675 .hangup = slcan_hangup,
676 .ioctl = slcan_ioctl,
677 .receive_buf = slcan_receive_buf,
678 .write_wakeup = slcan_write_wakeup,
681 static int __init slcan_init(void)
686 maxdev = 4; /* Sanity */
689 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
691 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
695 /* Fill in our line protocol discipline, and register it */
696 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
698 printk(KERN_ERR "slcan: can't register line discipline\n");
704 static void __exit slcan_exit(void)
707 struct net_device *dev;
709 unsigned long timeout = jiffies + HZ;
712 if (slcan_devs == NULL)
715 /* First of all: check for active disciplines and hangup them.
719 msleep_interruptible(100);
722 for (i = 0; i < maxdev; i++) {
726 sl = netdev_priv(dev);
727 spin_lock_bh(&sl->lock);
732 spin_unlock_bh(&sl->lock);
734 } while (busy && time_before(jiffies, timeout));
736 /* FIXME: hangup is async so we should wait when doing this second
739 for (i = 0; i < maxdev; i++) {
743 slcan_devs[i] = NULL;
745 sl = netdev_priv(dev);
747 printk(KERN_ERR "%s: tty discipline still running\n",
749 /* Intentionally leak the control block. */
750 dev->destructor = NULL;
753 unregister_netdev(dev);
759 i = tty_unregister_ldisc(N_SLCAN);
761 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
764 module_init(slcan_init);
765 module_exit(slcan_exit);