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Oliver Hartkoppa1044e32010-12-02 10:57:59 +00001/*
2 * slcan.c - serial line CAN interface driver (using tty line discipline)
3 *
Paul Gortmaker3396c782012-01-27 13:36:01 +00004 * This file is derived from linux/drivers/net/slip/slip.c
Oliver Hartkoppa1044e32010-12-02 10:57:59 +00005 *
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>
9 *
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.
14 *
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.
19 *
20 * You should have received a copy of the GNU General Public License along
Jeff Kirsher05780d92013-12-06 06:28:45 -080021 * with this program; if not, see http://www.gnu.org/licenses/gpl.html
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000022 *
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
34 * DAMAGE.
35 *
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000036 */
37
38#include <linux/module.h>
39#include <linux/moduleparam.h>
40
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000041#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>
David S. Miller84b3cdc2010-12-08 18:41:03 -080051#include <linux/sched.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000052#include <linux/delay.h>
53#include <linux/init.h>
Andy Shevchenko81fc70d2011-07-17 22:26:37 +000054#include <linux/kernel.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000055#include <linux/can.h>
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +010056#include <linux/can/skb.h>
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000057
Andi Kleenc477ebd2012-10-04 17:11:55 -070058static __initconst const char banner[] =
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000059 KERN_INFO "slcan: serial line CAN interface driver\n";
60
61MODULE_ALIAS_LDISC(N_SLCAN);
62MODULE_DESCRIPTION("serial line CAN interface");
63MODULE_LICENSE("GPL");
64MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
65
66#define SLCAN_MAGIC 0x53CA
67
68static int maxdev = 10; /* MAX number of SLCAN channels;
69 This can be overridden with
70 insmod slcan.ko maxdev=nnn */
71module_param(maxdev, int, 0);
72MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
73
74/* maximum rx buffer len: extended CAN frame with timestamp */
75#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
76
Andre Naujoks87397fe2013-09-13 19:37:13 +020077#define SLC_CMD_LEN 1
78#define SLC_SFF_ID_LEN 3
79#define SLC_EFF_ID_LEN 8
80
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000081struct slcan {
82 int magic;
83
84 /* Various fields. */
85 struct tty_struct *tty; /* ptr to TTY structure */
86 struct net_device *dev; /* easy for intr handling */
87 spinlock_t lock;
88
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 */
95
96 unsigned long flags; /* Flag values/ mode etc */
97#define SLF_INUSE 0 /* Channel in use */
98#define SLF_ERROR 1 /* Parity, etc. error */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +000099};
100
101static struct net_device **slcan_devs;
102
103 /************************************************************************
104 * SLCAN ENCAPSULATION FORMAT *
105 ************************************************************************/
106
107/*
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
113 * given can_id.
114 *
115 * The SLCAN ASCII representation of these different frame types is:
116 * <type> <id> <dlc> <data>*
117 *
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
124 *
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>
128 *
129 * Examples:
130 *
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
135 *
136 */
137
138 /************************************************************************
139 * STANDARD SLCAN DECAPSULATION *
140 ************************************************************************/
141
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000142/* Send one completely decapsulated can_frame to the network layer */
143static void slc_bump(struct slcan *sl)
144{
145 struct sk_buff *skb;
146 struct can_frame cf;
Andre Naujoks87397fe2013-09-13 19:37:13 +0200147 int i, tmp;
148 u32 tmpid;
149 char *cmd = sl->rbuff;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000150
Andre Naujoks87397fe2013-09-13 19:37:13 +0200151 cf.can_id = 0;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000152
Andre Naujoks87397fe2013-09-13 19:37:13 +0200153 switch (*cmd) {
154 case 'r':
155 cf.can_id = CAN_RTR_FLAG;
156 /* fallthrough */
157 case 't':
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;
163 break;
164 case 'R':
165 cf.can_id = CAN_RTR_FLAG;
166 /* fallthrough */
167 case 'T':
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000168 cf.can_id |= CAN_EFF_FLAG;
Andre Naujoks87397fe2013-09-13 19:37:13 +0200169 /* 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;
174 break;
175 default:
176 return;
177 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000178
Andre Naujoks87397fe2013-09-13 19:37:13 +0200179 if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
180 return;
181
182 cf.can_id |= tmpid;
183
184 /* get can_dlc from sanitized ASCII value */
185 if (cf.can_dlc >= '0' && cf.can_dlc < '9')
186 cf.can_dlc -= '0';
187 else
188 return;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000189
190 *(u64 *) (&cf.data) = 0; /* clear payload */
191
Andre Naujoks87397fe2013-09-13 19:37:13 +0200192 /* 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++);
196 if (tmp < 0)
197 return;
198 cf.data[i] = (tmp << 4);
199 tmp = hex_to_bin(*cmd++);
200 if (tmp < 0)
201 return;
202 cf.data[i] |= tmp;
203 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000204 }
205
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +0100206 skb = dev_alloc_skb(sizeof(struct can_frame) +
207 sizeof(struct can_skb_priv));
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000208 if (!skb)
209 return;
210
211 skb->dev = sl->dev;
212 skb->protocol = htons(ETH_P_CAN);
213 skb->pkt_type = PACKET_BROADCAST;
214 skb->ip_summed = CHECKSUM_UNNECESSARY;
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +0100215
Oliver Hartkopp2bf34402013-01-28 08:33:33 +0000216 can_skb_reserve(skb);
217 can_skb_prv(skb)->ifindex = sl->dev->ifindex;
Oliver Hartkopp156c2bb2013-01-17 18:43:39 +0100218
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000219 memcpy(skb_put(skb, sizeof(struct can_frame)),
220 &cf, sizeof(struct can_frame));
Oliver Hartkopp174c95d2011-08-10 05:18:59 +0000221 netif_rx_ni(skb);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000222
223 sl->dev->stats.rx_packets++;
224 sl->dev->stats.rx_bytes += cf.can_dlc;
225}
226
227/* parse tty input stream */
228static void slcan_unesc(struct slcan *sl, unsigned char s)
229{
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000230 if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
231 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
232 (sl->rcount > 4)) {
233 slc_bump(sl);
234 }
235 sl->rcount = 0;
236 } else {
237 if (!test_bit(SLF_ERROR, &sl->flags)) {
238 if (sl->rcount < SLC_MTU) {
239 sl->rbuff[sl->rcount++] = s;
240 return;
241 } else {
242 sl->dev->stats.rx_over_errors++;
243 set_bit(SLF_ERROR, &sl->flags);
244 }
245 }
246 }
247}
248
249 /************************************************************************
250 * STANDARD SLCAN ENCAPSULATION *
251 ************************************************************************/
252
253/* Encapsulate one can_frame and stuff into a TTY queue. */
254static void slc_encaps(struct slcan *sl, struct can_frame *cf)
255{
Andre Naujoks87397fe2013-09-13 19:37:13 +0200256 int actual, i;
257 unsigned char *pos;
258 unsigned char *endpos;
259 canid_t id = cf->can_id;
260
261 pos = sl->xbuff;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000262
263 if (cf->can_id & CAN_RTR_FLAG)
Andre Naujoks87397fe2013-09-13 19:37:13 +0200264 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000265 else
Andre Naujoks87397fe2013-09-13 19:37:13 +0200266 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000267
Andre Naujoks87397fe2013-09-13 19:37:13 +0200268 /* determine number of chars for the CAN-identifier */
269 if (cf->can_id & CAN_EFF_FLAG) {
270 id &= CAN_EFF_MASK;
271 endpos = pos + SLC_EFF_ID_LEN;
272 } else {
273 *pos |= 0x20; /* convert R/T to lower case for SFF */
274 id &= CAN_SFF_MASK;
275 endpos = pos + SLC_SFF_ID_LEN;
276 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000277
Andre Naujoks87397fe2013-09-13 19:37:13 +0200278 /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
279 pos++;
280 while (endpos >= pos) {
281 *endpos-- = hex_asc_upper[id & 0xf];
282 id >>= 4;
283 }
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000284
Andre Naujoks87397fe2013-09-13 19:37:13 +0200285 pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000286
Andre Naujoks87397fe2013-09-13 19:37:13 +0200287 *pos++ = cf->can_dlc + '0';
288
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]);
293 }
294
295 *pos++ = '\r';
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000296
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.
304 */
305 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
Andre Naujoks87397fe2013-09-13 19:37:13 +0200306 actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
307 sl->xleft = (pos - sl->xbuff) - actual;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000308 sl->xhead = sl->xbuff + actual;
309 sl->dev->stats.tx_bytes += cf->can_dlc;
310}
311
312/*
313 * Called by the driver when there's room for more data. If we have
314 * more packets to send, we send them here.
315 */
316static void slcan_write_wakeup(struct tty_struct *tty)
317{
318 int actual;
319 struct slcan *sl = (struct slcan *) tty->disc_data;
320
321 /* First make sure we're connected. */
322 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
323 return;
324
Andre Naujokscc9fa742013-09-13 19:37:11 +0200325 spin_lock(&sl->lock);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000326 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);
Andre Naujokscc9fa742013-09-13 19:37:11 +0200331 spin_unlock(&sl->lock);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000332 netif_wake_queue(sl->dev);
333 return;
334 }
335
336 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
337 sl->xleft -= actual;
338 sl->xhead += actual;
Andre Naujokscc9fa742013-09-13 19:37:11 +0200339 spin_unlock(&sl->lock);
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000340}
341
342/* Send a can_frame to a TTY queue. */
343static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
344{
345 struct slcan *sl = netdev_priv(dev);
346
347 if (skb->len != sizeof(struct can_frame))
348 goto out;
349
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);
354 goto out;
355 }
356 if (sl->tty == NULL) {
357 spin_unlock(&sl->lock);
358 goto out;
359 }
360
361 netif_stop_queue(sl->dev);
362 slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
363 spin_unlock(&sl->lock);
364
365out:
366 kfree_skb(skb);
367 return NETDEV_TX_OK;
368}
369
370
371/******************************************
372 * Routines looking at netdevice side.
373 ******************************************/
374
375/* Netdevice UP -> DOWN routine */
376static int slc_close(struct net_device *dev)
377{
378 struct slcan *sl = netdev_priv(dev);
379
380 spin_lock_bh(&sl->lock);
381 if (sl->tty) {
382 /* TTY discipline is running. */
383 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
384 }
385 netif_stop_queue(dev);
386 sl->rcount = 0;
387 sl->xleft = 0;
388 spin_unlock_bh(&sl->lock);
389
390 return 0;
391}
392
393/* Netdevice DOWN -> UP routine */
394static int slc_open(struct net_device *dev)
395{
396 struct slcan *sl = netdev_priv(dev);
397
398 if (sl->tty == NULL)
399 return -ENODEV;
400
401 sl->flags &= (1 << SLF_INUSE);
402 netif_start_queue(dev);
403 return 0;
404}
405
406/* Hook the destructor so we can free slcan devs at the right point in time */
407static void slc_free_netdev(struct net_device *dev)
408{
409 int i = dev->base_addr;
410 free_netdev(dev);
411 slcan_devs[i] = NULL;
412}
413
414static const struct net_device_ops slc_netdev_ops = {
415 .ndo_open = slc_open,
416 .ndo_stop = slc_close,
417 .ndo_start_xmit = slc_xmit,
418};
419
420static void slc_setup(struct net_device *dev)
421{
422 dev->netdev_ops = &slc_netdev_ops;
423 dev->destructor = slc_free_netdev;
424
425 dev->hard_header_len = 0;
426 dev->addr_len = 0;
427 dev->tx_queue_len = 10;
428
429 dev->mtu = sizeof(struct can_frame);
430 dev->type = ARPHRD_CAN;
431
432 /* New-style flags. */
433 dev->flags = IFF_NOARP;
Michał Mirosław34324dc2011-11-15 15:29:55 +0000434 dev->features = NETIF_F_HW_CSUM;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000435}
436
437/******************************************
438 Routines looking at TTY side.
439 ******************************************/
440
441/*
442 * Handle the 'receiver data ready' interrupt.
443 * This function is called by the 'tty_io' module in the kernel when
444 * a block of SLCAN data has been received, which can now be decapsulated
445 * and sent on to some IP layer for further processing. This will not
446 * be re-entered while running but other ldisc functions may be called
447 * in parallel
448 */
449
Linus Torvalds55db4c62011-06-04 06:33:24 +0900450static void slcan_receive_buf(struct tty_struct *tty,
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000451 const unsigned char *cp, char *fp, int count)
452{
453 struct slcan *sl = (struct slcan *) tty->disc_data;
454
455 if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
Linus Torvalds55db4c62011-06-04 06:33:24 +0900456 return;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000457
458 /* Read the characters out of the buffer */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900459 while (count--) {
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000460 if (fp && *fp++) {
461 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
462 sl->dev->stats.rx_errors++;
463 cp++;
464 continue;
465 }
466 slcan_unesc(sl, *cp++);
467 }
468}
469
470/************************************
471 * slcan_open helper routines.
472 ************************************/
473
474/* Collect hanged up channels */
475static void slc_sync(void)
476{
477 int i;
478 struct net_device *dev;
479 struct slcan *sl;
480
481 for (i = 0; i < maxdev; i++) {
482 dev = slcan_devs[i];
483 if (dev == NULL)
484 break;
485
486 sl = netdev_priv(dev);
Matvejchikov Ilya7ad711b2011-07-18 21:58:48 +0000487 if (sl->tty)
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000488 continue;
489 if (dev->flags & IFF_UP)
490 dev_close(dev);
491 }
492}
493
494/* Find a free SLCAN channel, and link in this `tty' line. */
495static struct slcan *slc_alloc(dev_t line)
496{
497 int i;
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000498 char name[IFNAMSIZ];
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000499 struct net_device *dev = NULL;
500 struct slcan *sl;
501
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000502 for (i = 0; i < maxdev; i++) {
503 dev = slcan_devs[i];
504 if (dev == NULL)
505 break;
506
507 }
508
509 /* Sorry, too many, all slots in use */
510 if (i >= maxdev)
511 return NULL;
512
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000513 sprintf(name, "slcan%d", i);
514 dev = alloc_netdev(sizeof(*sl), name, slc_setup);
515 if (!dev)
516 return NULL;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000517
Oliver Hartkopp2af4ba82011-07-14 21:49:19 +0000518 dev->base_addr = i;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000519 sl = netdev_priv(dev);
520
521 /* Initialize channel control data */
522 sl->magic = SLCAN_MAGIC;
523 sl->dev = dev;
524 spin_lock_init(&sl->lock);
525 slcan_devs[i] = dev;
526
527 return sl;
528}
529
530/*
531 * Open the high-level part of the SLCAN channel.
532 * This function is called by the TTY module when the
533 * SLCAN line discipline is called for. Because we are
534 * sure the tty line exists, we only have to link it to
535 * a free SLCAN channel...
536 *
537 * Called in process context serialized from other ldisc calls.
538 */
539
540static int slcan_open(struct tty_struct *tty)
541{
542 struct slcan *sl;
543 int err;
544
545 if (!capable(CAP_NET_ADMIN))
546 return -EPERM;
547
548 if (tty->ops->write == NULL)
549 return -EOPNOTSUPP;
550
551 /* RTnetlink lock is misused here to serialize concurrent
552 opens of slcan channels. There are better ways, but it is
553 the simplest one.
554 */
555 rtnl_lock();
556
557 /* Collect hanged up channels. */
558 slc_sync();
559
560 sl = tty->disc_data;
561
562 err = -EEXIST;
563 /* First make sure we're not already connected. */
564 if (sl && sl->magic == SLCAN_MAGIC)
565 goto err_exit;
566
567 /* OK. Find a free SLCAN channel to use. */
568 err = -ENFILE;
569 sl = slc_alloc(tty_devnum(tty));
570 if (sl == NULL)
571 goto err_exit;
572
573 sl->tty = tty;
574 tty->disc_data = sl;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000575
576 if (!test_bit(SLF_INUSE, &sl->flags)) {
577 /* Perform the low-level SLCAN initialization. */
578 sl->rcount = 0;
579 sl->xleft = 0;
580
581 set_bit(SLF_INUSE, &sl->flags);
582
583 err = register_netdevice(sl->dev);
584 if (err)
585 goto err_free_chan;
586 }
587
588 /* Done. We have linked the TTY line to a channel. */
589 rtnl_unlock();
590 tty->receive_room = 65536; /* We don't flow control */
Oliver Hartkopp0d4420a2011-05-10 13:12:30 -0700591
592 /* TTY layer expects 0 on success */
593 return 0;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000594
595err_free_chan:
596 sl->tty = NULL;
597 tty->disc_data = NULL;
598 clear_bit(SLF_INUSE, &sl->flags);
599
600err_exit:
601 rtnl_unlock();
602
603 /* Count references from TTY module */
604 return err;
605}
606
607/*
608 * Close down a SLCAN channel.
609 * This means flushing out any pending queues, and then returning. This
610 * call is serialized against other ldisc functions.
611 *
612 * We also use this method for a hangup event.
613 */
614
615static void slcan_close(struct tty_struct *tty)
616{
617 struct slcan *sl = (struct slcan *) tty->disc_data;
618
619 /* First make sure we're connected. */
620 if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
621 return;
622
623 tty->disc_data = NULL;
624 sl->tty = NULL;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000625
626 /* Flush network side */
627 unregister_netdev(sl->dev);
628 /* This will complete via sl_free_netdev */
629}
630
631static int slcan_hangup(struct tty_struct *tty)
632{
633 slcan_close(tty);
634 return 0;
635}
636
637/* Perform I/O control on an active SLCAN channel. */
638static int slcan_ioctl(struct tty_struct *tty, struct file *file,
639 unsigned int cmd, unsigned long arg)
640{
641 struct slcan *sl = (struct slcan *) tty->disc_data;
642 unsigned int tmp;
643
644 /* First make sure we're connected. */
645 if (!sl || sl->magic != SLCAN_MAGIC)
646 return -EINVAL;
647
648 switch (cmd) {
649 case SIOCGIFNAME:
650 tmp = strlen(sl->dev->name) + 1;
651 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
652 return -EFAULT;
653 return 0;
654
655 case SIOCSIFHWADDR:
656 return -EINVAL;
657
658 default:
659 return tty_mode_ioctl(tty, file, cmd, arg);
660 }
661}
662
663static struct tty_ldisc_ops slc_ldisc = {
664 .owner = THIS_MODULE,
665 .magic = TTY_LDISC_MAGIC,
666 .name = "slcan",
667 .open = slcan_open,
668 .close = slcan_close,
669 .hangup = slcan_hangup,
670 .ioctl = slcan_ioctl,
671 .receive_buf = slcan_receive_buf,
672 .write_wakeup = slcan_write_wakeup,
673};
674
675static int __init slcan_init(void)
676{
677 int status;
678
679 if (maxdev < 4)
680 maxdev = 4; /* Sanity */
681
682 printk(banner);
683 printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
684
685 slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
Joe Perchese404dec2012-01-29 12:56:23 +0000686 if (!slcan_devs)
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000687 return -ENOMEM;
Oliver Hartkoppa1044e32010-12-02 10:57:59 +0000688
689 /* Fill in our line protocol discipline, and register it */
690 status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
691 if (status) {
692 printk(KERN_ERR "slcan: can't register line discipline\n");
693 kfree(slcan_devs);
694 }
695 return status;
696}
697
698static void __exit slcan_exit(void)
699{
700 int i;
701 struct net_device *dev;
702 struct slcan *sl;
703 unsigned long timeout = jiffies + HZ;
704 int busy = 0;
705
706 if (slcan_devs == NULL)
707 return;
708
709 /* First of all: check for active disciplines and hangup them.
710 */
711 do {
712 if (busy)
713 msleep_interruptible(100);
714
715 busy = 0;
716 for (i = 0; i < maxdev; i++) {
717 dev = slcan_devs[i];
718 if (!dev)
719 continue;
720 sl = netdev_priv(dev);
721 spin_lock_bh(&sl->lock);
722 if (sl->tty) {
723 busy++;
724 tty_hangup(sl->tty);
725 }
726 spin_unlock_bh(&sl->lock);
727 }
728 } while (busy && time_before(jiffies, timeout));
729
730 /* FIXME: hangup is async so we should wait when doing this second
731 phase */
732
733 for (i = 0; i < maxdev; i++) {
734 dev = slcan_devs[i];
735 if (!dev)
736 continue;
737 slcan_devs[i] = NULL;
738
739 sl = netdev_priv(dev);
740 if (sl->tty) {
741 printk(KERN_ERR "%s: tty discipline still running\n",
742 dev->name);
743 /* Intentionally leak the control block. */
744 dev->destructor = NULL;
745 }
746
747 unregister_netdev(dev);
748 }
749
750 kfree(slcan_devs);
751 slcan_devs = NULL;
752
753 i = tty_unregister_ldisc(N_SLCAN);
754 if (i)
755 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
756}
757
758module_init(slcan_init);
759module_exit(slcan_exit);