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>
59 static __initconst const char banner[] =
60 KERN_INFO "slcan: serial line CAN interface driver\n";
62 MODULE_ALIAS_LDISC(N_SLCAN);
63 MODULE_DESCRIPTION("serial line CAN interface");
64 MODULE_LICENSE("GPL");
65 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
67 #define SLCAN_MAGIC 0x53CA
69 static int maxdev = 10; /* MAX number of SLCAN channels;
70 This can be overridden with
71 insmod slcan.ko maxdev=nnn */
72 module_param(maxdev, int, 0);
73 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
75 /* maximum rx buffer len: extended CAN frame with timestamp */
76 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
82 struct tty_struct *tty; /* ptr to TTY structure */
83 struct net_device *dev; /* easy for intr handling */
86 /* These are pointers to the malloc()ed frame buffers. */
87 unsigned char rbuff[SLC_MTU]; /* receiver buffer */
88 int rcount; /* received chars counter */
89 unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
90 unsigned char *xhead; /* pointer to next XMIT byte */
91 int xleft; /* bytes left in XMIT queue */
93 unsigned long flags; /* Flag values/ mode etc */
94 #define SLF_INUSE 0 /* Channel in use */
95 #define SLF_ERROR 1 /* Parity, etc. error */
98 static struct net_device **slcan_devs;
100 /************************************************************************
101 * SLCAN ENCAPSULATION FORMAT *
102 ************************************************************************/
105 * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
106 * frame format) a data length code (can_dlc) which can be from 0 to 8
107 * and up to <can_dlc> data bytes as payload.
108 * Additionally a CAN frame may become a remote transmission frame if the
109 * RTR-bit is set. This causes another ECU to send a CAN frame with the
112 * The SLCAN ASCII representation of these different frame types is:
113 * <type> <id> <dlc> <data>*
115 * Extended frames (29 bit) are defined by capital characters in the type.
116 * RTR frames are defined as 'r' types - normal frames have 't' type:
117 * t => 11 bit data frame
118 * r => 11 bit RTR frame
119 * T => 29 bit data frame
120 * R => 29 bit RTR frame
122 * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
123 * The <dlc> is a one byte ASCII number ('0' - '8')
124 * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
128 * t1230 : can_id 0x123, can_dlc 0, no data
129 * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
130 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
131 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
135 /************************************************************************
136 * STANDARD SLCAN DECAPSULATION *
137 ************************************************************************/
139 /* Send one completely decapsulated can_frame to the network layer */
140 static void slc_bump(struct slcan *sl)
146 char cmd = sl->rbuff[0];
148 if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
151 if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
152 dlc_pos = 4; /* dlc position tiiid */
154 dlc_pos = 9; /* dlc position Tiiiiiiiid */
156 if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
159 cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
161 sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
163 if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
168 if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
169 cf.can_id |= CAN_EFF_FLAG;
171 if ((cmd | 0x20) == 'r') /* RTR frame */
172 cf.can_id |= CAN_RTR_FLAG;
174 *(u64 *) (&cf.data) = 0; /* clear payload */
176 for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
177 tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
180 cf.data[i] = (tmp << 4);
181 tmp = hex_to_bin(sl->rbuff[dlc_pos++]);
187 skb = dev_alloc_skb(sizeof(struct can_frame));
192 skb->protocol = htons(ETH_P_CAN);
193 skb->pkt_type = PACKET_BROADCAST;
194 skb->ip_summed = CHECKSUM_UNNECESSARY;
195 memcpy(skb_put(skb, sizeof(struct can_frame)),
196 &cf, sizeof(struct can_frame));
199 sl->dev->stats.rx_packets++;
200 sl->dev->stats.rx_bytes += cf.can_dlc;
203 /* parse tty input stream */
204 static void slcan_unesc(struct slcan *sl, unsigned char s)
207 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
208 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
214 if (!test_bit(SLF_ERROR, &sl->flags)) {
215 if (sl->rcount < SLC_MTU) {
216 sl->rbuff[sl->rcount++] = s;
219 sl->dev->stats.rx_over_errors++;
220 set_bit(SLF_ERROR, &sl->flags);
226 /************************************************************************
227 * STANDARD SLCAN ENCAPSULATION *
228 ************************************************************************/
230 /* Encapsulate one can_frame and stuff into a TTY queue. */
231 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
236 if (cf->can_id & CAN_RTR_FLAG)
237 cmd = 'R'; /* becomes 'r' in standard frame format */
239 cmd = 'T'; /* becomes 't' in standard frame format */
241 if (cf->can_id & CAN_EFF_FLAG)
242 sprintf(sl->xbuff, "%c%08X%d", cmd,
243 cf->can_id & CAN_EFF_MASK, cf->can_dlc);
245 sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
246 cf->can_id & CAN_SFF_MASK, cf->can_dlc);
248 idx = strlen(sl->xbuff);
250 for (i = 0; i < cf->can_dlc; i++)
251 sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
253 strcat(sl->xbuff, "\r"); /* add terminating character */
255 /* Order of next two lines is *very* important.
256 * When we are sending a little amount of data,
257 * the transfer may be completed inside the ops->write()
258 * routine, because it's running with interrupts enabled.
259 * In this case we *never* got WRITE_WAKEUP event,
260 * if we did not request it before write operation.
261 * 14 Oct 1994 Dmitry Gorodchanin.
263 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
264 actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
265 sl->xleft = strlen(sl->xbuff) - actual;
266 sl->xhead = sl->xbuff + actual;
267 sl->dev->stats.tx_bytes += cf->can_dlc;
271 * Called by the driver when there's room for more data. If we have
272 * more packets to send, we send them here.
274 static void slcan_write_wakeup(struct tty_struct *tty)
277 struct slcan *sl = (struct slcan *) tty->disc_data;
279 /* First make sure we're connected. */
280 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
283 if (sl->xleft <= 0) {
284 /* Now serial buffer is almost free & we can start
285 * transmission of another packet */
286 sl->dev->stats.tx_packets++;
287 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
288 netif_wake_queue(sl->dev);
292 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
297 /* Send a can_frame to a TTY queue. */
298 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
300 struct slcan *sl = netdev_priv(dev);
302 if (skb->len != sizeof(struct can_frame))
305 spin_lock(&sl->lock);
306 if (!netif_running(dev)) {
307 spin_unlock(&sl->lock);
308 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
311 if (sl->tty == NULL) {
312 spin_unlock(&sl->lock);
316 netif_stop_queue(sl->dev);
317 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
318 spin_unlock(&sl->lock);
326 /******************************************
327 * Routines looking at netdevice side.
328 ******************************************/
330 /* Netdevice UP -> DOWN routine */
331 static int slc_close(struct net_device *dev)
333 struct slcan *sl = netdev_priv(dev);
335 spin_lock_bh(&sl->lock);
337 /* TTY discipline is running. */
338 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
340 netif_stop_queue(dev);
343 spin_unlock_bh(&sl->lock);
348 /* Netdevice DOWN -> UP routine */
349 static int slc_open(struct net_device *dev)
351 struct slcan *sl = netdev_priv(dev);
356 sl->flags &= (1 << SLF_INUSE);
357 netif_start_queue(dev);
361 /* Hook the destructor so we can free slcan devs at the right point in time */
362 static void slc_free_netdev(struct net_device *dev)
364 int i = dev->base_addr;
366 slcan_devs[i] = NULL;
369 static const struct net_device_ops slc_netdev_ops = {
370 .ndo_open = slc_open,
371 .ndo_stop = slc_close,
372 .ndo_start_xmit = slc_xmit,
375 static void slc_setup(struct net_device *dev)
377 dev->netdev_ops = &slc_netdev_ops;
378 dev->destructor = slc_free_netdev;
380 dev->hard_header_len = 0;
382 dev->tx_queue_len = 10;
384 dev->mtu = sizeof(struct can_frame);
385 dev->type = ARPHRD_CAN;
387 /* New-style flags. */
388 dev->flags = IFF_NOARP;
389 dev->features = NETIF_F_HW_CSUM;
392 /******************************************
393 Routines looking at TTY side.
394 ******************************************/
397 * Handle the 'receiver data ready' interrupt.
398 * This function is called by the 'tty_io' module in the kernel when
399 * a block of SLCAN data has been received, which can now be decapsulated
400 * and sent on to some IP layer for further processing. This will not
401 * be re-entered while running but other ldisc functions may be called
405 static void slcan_receive_buf(struct tty_struct *tty,
406 const unsigned char *cp, char *fp, int count)
408 struct slcan *sl = (struct slcan *) tty->disc_data;
410 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
413 /* Read the characters out of the buffer */
416 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
417 sl->dev->stats.rx_errors++;
421 slcan_unesc(sl, *cp++);
425 /************************************
426 * slcan_open helper routines.
427 ************************************/
429 /* Collect hanged up channels */
430 static void slc_sync(void)
433 struct net_device *dev;
436 for (i = 0; i < maxdev; i++) {
441 sl = netdev_priv(dev);
444 if (dev->flags & IFF_UP)
449 /* Find a free SLCAN channel, and link in this `tty' line. */
450 static struct slcan *slc_alloc(dev_t line)
454 struct net_device *dev = NULL;
457 for (i = 0; i < maxdev; i++) {
464 /* Sorry, too many, all slots in use */
468 sprintf(name, "slcan%d", i);
469 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
474 sl = netdev_priv(dev);
476 /* Initialize channel control data */
477 sl->magic = SLCAN_MAGIC;
479 spin_lock_init(&sl->lock);
486 * Open the high-level part of the SLCAN channel.
487 * This function is called by the TTY module when the
488 * SLCAN line discipline is called for. Because we are
489 * sure the tty line exists, we only have to link it to
490 * a free SLCAN channel...
492 * Called in process context serialized from other ldisc calls.
495 static int slcan_open(struct tty_struct *tty)
500 if (!capable(CAP_NET_ADMIN))
503 if (tty->ops->write == NULL)
506 /* RTnetlink lock is misused here to serialize concurrent
507 opens of slcan channels. There are better ways, but it is
512 /* Collect hanged up channels. */
518 /* First make sure we're not already connected. */
519 if (sl && sl->magic == SLCAN_MAGIC)
522 /* OK. Find a free SLCAN channel to use. */
524 sl = slc_alloc(tty_devnum(tty));
531 if (!test_bit(SLF_INUSE, &sl->flags)) {
532 /* Perform the low-level SLCAN initialization. */
536 set_bit(SLF_INUSE, &sl->flags);
538 err = register_netdevice(sl->dev);
543 /* Done. We have linked the TTY line to a channel. */
545 tty->receive_room = 65536; /* We don't flow control */
547 /* TTY layer expects 0 on success */
552 tty->disc_data = NULL;
553 clear_bit(SLF_INUSE, &sl->flags);
558 /* Count references from TTY module */
563 * Close down a SLCAN channel.
564 * This means flushing out any pending queues, and then returning. This
565 * call is serialized against other ldisc functions.
567 * We also use this method for a hangup event.
570 static void slcan_close(struct tty_struct *tty)
572 struct slcan *sl = (struct slcan *) tty->disc_data;
574 /* First make sure we're connected. */
575 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
578 tty->disc_data = NULL;
581 /* Flush network side */
582 unregister_netdev(sl->dev);
583 /* This will complete via sl_free_netdev */
586 static int slcan_hangup(struct tty_struct *tty)
592 /* Perform I/O control on an active SLCAN channel. */
593 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
594 unsigned int cmd, unsigned long arg)
596 struct slcan *sl = (struct slcan *) tty->disc_data;
599 /* First make sure we're connected. */
600 if (!sl || sl->magic != SLCAN_MAGIC)
605 tmp = strlen(sl->dev->name) + 1;
606 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
614 return tty_mode_ioctl(tty, file, cmd, arg);
618 static struct tty_ldisc_ops slc_ldisc = {
619 .owner = THIS_MODULE,
620 .magic = TTY_LDISC_MAGIC,
623 .close = slcan_close,
624 .hangup = slcan_hangup,
625 .ioctl = slcan_ioctl,
626 .receive_buf = slcan_receive_buf,
627 .write_wakeup = slcan_write_wakeup,
630 static int __init slcan_init(void)
635 maxdev = 4; /* Sanity */
638 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
640 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
644 /* Fill in our line protocol discipline, and register it */
645 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
647 printk(KERN_ERR "slcan: can't register line discipline\n");
653 static void __exit slcan_exit(void)
656 struct net_device *dev;
658 unsigned long timeout = jiffies + HZ;
661 if (slcan_devs == NULL)
664 /* First of all: check for active disciplines and hangup them.
668 msleep_interruptible(100);
671 for (i = 0; i < maxdev; i++) {
675 sl = netdev_priv(dev);
676 spin_lock_bh(&sl->lock);
681 spin_unlock_bh(&sl->lock);
683 } while (busy && time_before(jiffies, timeout));
685 /* FIXME: hangup is async so we should wait when doing this second
688 for (i = 0; i < maxdev; i++) {
692 slcan_devs[i] = NULL;
694 sl = netdev_priv(dev);
696 printk(KERN_ERR "%s: tty discipline still running\n",
698 /* Intentionally leak the control block. */
699 dev->destructor = NULL;
702 unregister_netdev(dev);
708 i = tty_unregister_ldisc(N_SLCAN);
710 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
713 module_init(slcan_init);
714 module_exit(slcan_exit);