drivers/net/can/slcan.c

   1 /*
   2  * slcan.c - serial line CAN interface driver (using tty line discipline)
   3  *
   4  * This file is derived from linux/drivers/net/slip/slip.c
   5  *
   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
  21  * with this program; if not, see http://www.gnu.org/licenses/gpl.html
  22  *
  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  *
  36  */
  37
  38 #include <linux/module.h>
  39 #include <linux/moduleparam.h>
  40
  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>
  58
  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>");
  63
  64 #define SLCAN_MAGIC 0x53CA
  65
  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");
  71
  72 /* maximum rx buffer len: extended CAN frame with timestamp */
  73 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
  74
  75 #define SLC_CMD_LEN 1
  76 #define SLC_SFF_ID_LEN 3
  77 #define SLC_EFF_ID_LEN 8
  78
  79 struct slcan {
  80         int                     magic;
  81
  82         /* Various fields. */
  83         struct tty_struct       *tty;           /* ptr to TTY structure      */
  84         struct net_device       *dev;           /* easy for intr handling    */
  85         spinlock_t              lock;
  86         struct work_struct      tx_work;        /* Flushes transmit buffer   */
  87
  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  */
  94
  95         unsigned long           flags;          /* Flag values/ mode etc     */
  96 #define SLF_INUSE               0               /* Channel in use            */
  97 #define SLF_ERROR               1               /* Parity, etc. error        */
  98 };
  99
 100 static struct net_device **slcan_devs;
 101
 102  /************************************************************************
 103   *                     SLCAN ENCAPSULATION FORMAT                       *
 104   ************************************************************************/
 105
 106 /*
 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
 112  * given can_id.
 113  *
 114  * The SLCAN ASCII representation of these different frame types is:
 115  * <type> <id> <dlc> <data>*
 116  *
 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
 123  *
 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>
 127  *
 128  * Examples:
 129  *
 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
 134  *
 135  */
 136
 137  /************************************************************************
 138   *                     STANDARD SLCAN DECAPSULATION                     *
 139   ************************************************************************/
 140
 141 /* Send one completely decapsulated can_frame to the network layer */
 142 static void slc_bump(struct slcan *sl)
 143 {
 144         struct sk_buff *skb;
 145         struct can_frame cf;
 146         int i, tmp;
 147         u32 tmpid;
 148         char *cmd = sl->rbuff;
 149
 150         cf.can_id = 0;
 151
 152         switch (*cmd) {
 153         case 'r':
 154                 cf.can_id = CAN_RTR_FLAG;
 155                 /* fallthrough */
 156         case 't':
 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;
 162                 break;
 163         case 'R':
 164                 cf.can_id = CAN_RTR_FLAG;
 165                 /* fallthrough */
 166         case 'T':
 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;
 173                 break;
 174         default:
 175                 return;
 176         }
 177
 178         if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
 179                 return;
 180
 181         cf.can_id |= tmpid;
 182
 183         /* get can_dlc from sanitized ASCII value */
 184         if (cf.can_dlc >= '0' && cf.can_dlc < '9')
 185                 cf.can_dlc -= '0';
 186         else
 187                 return;
 188
 189         *(u64 *) (&cf.data) = 0; /* clear payload */
 190
 191         /* RTR frames may have a dlc > 0 but they never have any data bytes */
 192         if (!(cf.can_id & CAN_RTR_FLAG)) {
 193                 for (i = 0; i < cf.can_dlc; i++) {
 194                         tmp = hex_to_bin(*cmd++);
 195                         if (tmp < 0)
 196                                 return;
 197                         cf.data[i] = (tmp << 4);
 198                         tmp = hex_to_bin(*cmd++);
 199                         if (tmp < 0)
 200                                 return;
 201                         cf.data[i] |= tmp;
 202                 }
 203         }
 204
 205         skb = dev_alloc_skb(sizeof(struct can_frame) +
 206                             sizeof(struct can_skb_priv));
 207         if (!skb)
 208                 return;
 209
 210         skb->dev = sl->dev;
 211         skb->protocol = htons(ETH_P_CAN);
 212         skb->pkt_type = PACKET_BROADCAST;
 213         skb->ip_summed = CHECKSUM_UNNECESSARY;
 214
 215         can_skb_reserve(skb);
 216         can_skb_prv(skb)->ifindex = sl->dev->ifindex;
 217
 218         memcpy(skb_put(skb, sizeof(struct can_frame)),
 219                &cf, sizeof(struct can_frame));
 220         netif_rx_ni(skb);
 221
 222         sl->dev->stats.rx_packets++;
 223         sl->dev->stats.rx_bytes += cf.can_dlc;
 224 }
 225
 226 /* parse tty input stream */
 227 static void slcan_unesc(struct slcan *sl, unsigned char s)
 228 {
 229         if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
 230                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 231                     (sl->rcount > 4))  {
 232                         slc_bump(sl);
 233                 }
 234                 sl->rcount = 0;
 235         } else {
 236                 if (!test_bit(SLF_ERROR, &sl->flags))  {
 237                         if (sl->rcount < SLC_MTU)  {
 238                                 sl->rbuff[sl->rcount++] = s;
 239                                 return;
 240                         } else {
 241                                 sl->dev->stats.rx_over_errors++;
 242                                 set_bit(SLF_ERROR, &sl->flags);
 243                         }
 244                 }
 245         }
 246 }
 247
 248  /************************************************************************
 249   *                     STANDARD SLCAN ENCAPSULATION                     *
 250   ************************************************************************/
 251
 252 /* Encapsulate one can_frame and stuff into a TTY queue. */
 253 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
 254 {
 255         int actual, i;
 256         unsigned char *pos;
 257         unsigned char *endpos;
 258         canid_t id = cf->can_id;
 259
 260         pos = sl->xbuff;
 261
 262         if (cf->can_id & CAN_RTR_FLAG)
 263                 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
 264         else
 265                 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
 266
 267         /* determine number of chars for the CAN-identifier */
 268         if (cf->can_id & CAN_EFF_FLAG) {
 269                 id &= CAN_EFF_MASK;
 270                 endpos = pos + SLC_EFF_ID_LEN;
 271         } else {
 272                 *pos |= 0x20; /* convert R/T to lower case for SFF */
 273                 id &= CAN_SFF_MASK;
 274                 endpos = pos + SLC_SFF_ID_LEN;
 275         }
 276
 277         /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
 278         pos++;
 279         while (endpos >= pos) {
 280                 *endpos-- = hex_asc_upper[id & 0xf];
 281                 id >>= 4;
 282         }
 283
 284         pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
 285
 286         *pos++ = cf->can_dlc + '0';
 287
 288         /* RTR frames may have a dlc > 0 but they never have any data bytes */
 289         if (!(cf->can_id & CAN_RTR_FLAG)) {
 290                 for (i = 0; i < cf->can_dlc; i++)
 291                         pos = hex_byte_pack_upper(pos, cf->data[i]);
 292         }
 293
 294         *pos++ = '\r';
 295
 296         /* Order of next two lines is *very* important.
 297          * When we are sending a little amount of data,
 298          * the transfer may be completed inside the ops->write()
 299          * routine, because it's running with interrupts enabled.
 300          * In this case we *never* got WRITE_WAKEUP event,
 301          * if we did not request it before write operation.
 302          *       14 Oct 1994  Dmitry Gorodchanin.
 303          */
 304         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 305         actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
 306         sl->xleft = (pos - sl->xbuff) - actual;
 307         sl->xhead = sl->xbuff + actual;
 308         sl->dev->stats.tx_bytes += cf->can_dlc;
 309 }
 310
 311 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 312 static void slcan_transmit(struct work_struct *work)
 313 {
 314         struct slcan *sl = container_of(work, struct slcan, tx_work);
 315         int actual;
 316
 317         spin_lock_bh(&sl->lock);
 318         /* First make sure we're connected. */
 319         if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
 320                 spin_unlock_bh(&sl->lock);
 321                 return;
 322         }
 323
 324         if (sl->xleft <= 0)  {
 325                 /* Now serial buffer is almost free & we can start
 326                  * transmission of another packet */
 327                 sl->dev->stats.tx_packets++;
 328                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 329                 spin_unlock_bh(&sl->lock);
 330                 netif_wake_queue(sl->dev);
 331                 return;
 332         }
 333
 334         actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
 335         sl->xleft -= actual;
 336         sl->xhead += actual;
 337         spin_unlock_bh(&sl->lock);
 338 }
 339
 340 /*
 341  * Called by the driver when there's room for more data.
 342  * Schedule the transmit.
 343  */
 344 static void slcan_write_wakeup(struct tty_struct *tty)
 345 {
 346         struct slcan *sl = tty->disc_data;
 347
 348         schedule_work(&sl->tx_work);
 349 }
 350
 351 /* Send a can_frame to a TTY queue. */
 352 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
 353 {
 354         struct slcan *sl = netdev_priv(dev);
 355
 356         if (skb->len != sizeof(struct can_frame))
 357                 goto out;
 358
 359         spin_lock(&sl->lock);
 360         if (!netif_running(dev))  {
 361                 spin_unlock(&sl->lock);
 362                 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
 363                 goto out;
 364         }
 365         if (sl->tty == NULL) {
 366                 spin_unlock(&sl->lock);
 367                 goto out;
 368         }
 369
 370         netif_stop_queue(sl->dev);
 371         slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
 372         spin_unlock(&sl->lock);
 373
 374 out:
 375         kfree_skb(skb);
 376         return NETDEV_TX_OK;
 377 }
 378
 379
 380 /******************************************
 381  *   Routines looking at netdevice side.
 382  ******************************************/
 383
 384 /* Netdevice UP -> DOWN routine */
 385 static int slc_close(struct net_device *dev)
 386 {
 387         struct slcan *sl = netdev_priv(dev);
 388
 389         spin_lock_bh(&sl->lock);
 390         if (sl->tty) {
 391                 /* TTY discipline is running. */
 392                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 393         }
 394         netif_stop_queue(dev);
 395         sl->rcount   = 0;
 396         sl->xleft    = 0;
 397         spin_unlock_bh(&sl->lock);
 398
 399         return 0;
 400 }
 401
 402 /* Netdevice DOWN -> UP routine */
 403 static int slc_open(struct net_device *dev)
 404 {
 405         struct slcan *sl = netdev_priv(dev);
 406
 407         if (sl->tty == NULL)
 408                 return -ENODEV;
 409
 410         sl->flags &= (1 << SLF_INUSE);
 411         netif_start_queue(dev);
 412         return 0;
 413 }
 414
 415 /* Hook the destructor so we can free slcan devs at the right point in time */
 416 static void slc_free_netdev(struct net_device *dev)
 417 {
 418         int i = dev->base_addr;
 419         free_netdev(dev);
 420         slcan_devs[i] = NULL;
 421 }
 422
 423 static int slcan_change_mtu(struct net_device *dev, int new_mtu)
 424 {
 425         return -EINVAL;
 426 }
 427
 428 static const struct net_device_ops slc_netdev_ops = {
 429         .ndo_open               = slc_open,
 430         .ndo_stop               = slc_close,
 431         .ndo_start_xmit         = slc_xmit,
 432         .ndo_change_mtu         = slcan_change_mtu,
 433 };
 434
 435 static void slc_setup(struct net_device *dev)
 436 {
 437         dev->netdev_ops         = &slc_netdev_ops;
 438         dev->destructor         = slc_free_netdev;
 439
 440         dev->hard_header_len    = 0;
 441         dev->addr_len           = 0;
 442         dev->tx_queue_len       = 10;
 443
 444         dev->mtu                = sizeof(struct can_frame);
 445         dev->type               = ARPHRD_CAN;
 446
 447         /* New-style flags. */
 448         dev->flags              = IFF_NOARP;
 449         dev->features           = NETIF_F_HW_CSUM;
 450 }
 451
 452 /******************************************
 453   Routines looking at TTY side.
 454  ******************************************/
 455
 456 /*
 457  * Handle the 'receiver data ready' interrupt.
 458  * This function is called by the 'tty_io' module in the kernel when
 459  * a block of SLCAN data has been received, which can now be decapsulated
 460  * and sent on to some IP layer for further processing. This will not
 461  * be re-entered while running but other ldisc functions may be called
 462  * in parallel
 463  */
 464
 465 static void slcan_receive_buf(struct tty_struct *tty,
 466                               const unsigned char *cp, char *fp, int count)
 467 {
 468         struct slcan *sl = (struct slcan *) tty->disc_data;
 469
 470         if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
 471                 return;
 472
 473         /* Read the characters out of the buffer */
 474         while (count--) {
 475                 if (fp && *fp++) {
 476                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 477                                 sl->dev->stats.rx_errors++;
 478                         cp++;
 479                         continue;
 480                 }
 481                 slcan_unesc(sl, *cp++);
 482         }
 483 }
 484
 485 /************************************
 486  *  slcan_open helper routines.
 487  ************************************/
 488
 489 /* Collect hanged up channels */
 490 static void slc_sync(void)
 491 {
 492         int i;
 493         struct net_device *dev;
 494         struct slcan      *sl;
 495
 496         for (i = 0; i < maxdev; i++) {
 497                 dev = slcan_devs[i];
 498                 if (dev == NULL)
 499                         break;
 500
 501                 sl = netdev_priv(dev);
 502                 if (sl->tty)
 503                         continue;
 504                 if (dev->flags & IFF_UP)
 505                         dev_close(dev);
 506         }
 507 }
 508
 509 /* Find a free SLCAN channel, and link in this `tty' line. */
 510 static struct slcan *slc_alloc(dev_t line)
 511 {
 512         int i;
 513         char name[IFNAMSIZ];
 514         struct net_device *dev = NULL;
 515         struct slcan       *sl;
 516
 517         for (i = 0; i < maxdev; i++) {
 518                 dev = slcan_devs[i];
 519                 if (dev == NULL)
 520                         break;
 521
 522         }
 523
 524         /* Sorry, too many, all slots in use */
 525         if (i >= maxdev)
 526                 return NULL;
 527
 528         sprintf(name, "slcan%d", i);
 529         dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, slc_setup);
 530         if (!dev)
 531                 return NULL;
 532
 533         dev->base_addr  = i;
 534         sl = netdev_priv(dev);
 535
 536         /* Initialize channel control data */
 537         sl->magic = SLCAN_MAGIC;
 538         sl->dev = dev;
 539         spin_lock_init(&sl->lock);
 540         INIT_WORK(&sl->tx_work, slcan_transmit);
 541         slcan_devs[i] = dev;
 542
 543         return sl;
 544 }
 545
 546 /*
 547  * Open the high-level part of the SLCAN channel.
 548  * This function is called by the TTY module when the
 549  * SLCAN line discipline is called for.  Because we are
 550  * sure the tty line exists, we only have to link it to
 551  * a free SLCAN channel...
 552  *
 553  * Called in process context serialized from other ldisc calls.
 554  */
 555
 556 static int slcan_open(struct tty_struct *tty)
 557 {
 558         struct slcan *sl;
 559         int err;
 560
 561         if (!capable(CAP_NET_ADMIN))
 562                 return -EPERM;
 563
 564         if (tty->ops->write == NULL)
 565                 return -EOPNOTSUPP;
 566
 567         /* RTnetlink lock is misused here to serialize concurrent
 568            opens of slcan channels. There are better ways, but it is
 569            the simplest one.
 570          */
 571         rtnl_lock();
 572
 573         /* Collect hanged up channels. */
 574         slc_sync();
 575
 576         sl = tty->disc_data;
 577
 578         err = -EEXIST;
 579         /* First make sure we're not already connected. */
 580         if (sl && sl->magic == SLCAN_MAGIC)
 581                 goto err_exit;
 582
 583         /* OK.  Find a free SLCAN channel to use. */
 584         err = -ENFILE;
 585         sl = slc_alloc(tty_devnum(tty));
 586         if (sl == NULL)
 587                 goto err_exit;
 588
 589         sl->tty = tty;
 590         tty->disc_data = sl;
 591
 592         if (!test_bit(SLF_INUSE, &sl->flags)) {
 593                 /* Perform the low-level SLCAN initialization. */
 594                 sl->rcount   = 0;
 595                 sl->xleft    = 0;
 596
 597                 set_bit(SLF_INUSE, &sl->flags);
 598
 599                 err = register_netdevice(sl->dev);
 600                 if (err)
 601                         goto err_free_chan;
 602         }
 603
 604         /* Done.  We have linked the TTY line to a channel. */
 605         rtnl_unlock();
 606         tty->receive_room = 65536;      /* We don't flow control */
 607
 608         /* TTY layer expects 0 on success */
 609         return 0;
 610
 611 err_free_chan:
 612         sl->tty = NULL;
 613         tty->disc_data = NULL;
 614         clear_bit(SLF_INUSE, &sl->flags);
 615
 616 err_exit:
 617         rtnl_unlock();
 618
 619         /* Count references from TTY module */
 620         return err;
 621 }
 622
 623 /*
 624  * Close down a SLCAN channel.
 625  * This means flushing out any pending queues, and then returning. This
 626  * call is serialized against other ldisc functions.
 627  *
 628  * We also use this method for a hangup event.
 629  */
 630
 631 static void slcan_close(struct tty_struct *tty)
 632 {
 633         struct slcan *sl = (struct slcan *) tty->disc_data;
 634
 635         /* First make sure we're connected. */
 636         if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
 637                 return;
 638
 639         spin_lock_bh(&sl->lock);
 640         tty->disc_data = NULL;
 641         sl->tty = NULL;
 642         spin_unlock_bh(&sl->lock);
 643
 644         flush_work(&sl->tx_work);
 645
 646         /* Flush network side */
 647         unregister_netdev(sl->dev);
 648         /* This will complete via sl_free_netdev */
 649 }
 650
 651 static int slcan_hangup(struct tty_struct *tty)
 652 {
 653         slcan_close(tty);
 654         return 0;
 655 }
 656
 657 /* Perform I/O control on an active SLCAN channel. */
 658 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
 659                        unsigned int cmd, unsigned long arg)
 660 {
 661         struct slcan *sl = (struct slcan *) tty->disc_data;
 662         unsigned int tmp;
 663
 664         /* First make sure we're connected. */
 665         if (!sl || sl->magic != SLCAN_MAGIC)
 666                 return -EINVAL;
 667
 668         switch (cmd) {
 669         case SIOCGIFNAME:
 670                 tmp = strlen(sl->dev->name) + 1;
 671                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
 672                         return -EFAULT;
 673                 return 0;
 674
 675         case SIOCSIFHWADDR:
 676                 return -EINVAL;
 677
 678         default:
 679                 return tty_mode_ioctl(tty, file, cmd, arg);
 680         }
 681 }
 682
 683 static struct tty_ldisc_ops slc_ldisc = {
 684         .owner          = THIS_MODULE,
 685         .magic          = TTY_LDISC_MAGIC,
 686         .name           = "slcan",
 687         .open           = slcan_open,
 688         .close          = slcan_close,
 689         .hangup         = slcan_hangup,
 690         .ioctl          = slcan_ioctl,
 691         .receive_buf    = slcan_receive_buf,
 692         .write_wakeup   = slcan_write_wakeup,
 693 };
 694
 695 static int __init slcan_init(void)
 696 {
 697         int status;
 698
 699         if (maxdev < 4)
 700                 maxdev = 4; /* Sanity */
 701
 702         pr_info("slcan: serial line CAN interface driver\n");
 703         pr_info("slcan: %d dynamic interface channels.\n", maxdev);
 704
 705         slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
 706         if (!slcan_devs)
 707                 return -ENOMEM;
 708
 709         /* Fill in our line protocol discipline, and register it */
 710         status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
 711         if (status)  {
 712                 printk(KERN_ERR "slcan: can't register line discipline\n");
 713                 kfree(slcan_devs);
 714         }
 715         return status;
 716 }
 717
 718 static void __exit slcan_exit(void)
 719 {
 720         int i;
 721         struct net_device *dev;
 722         struct slcan *sl;
 723         unsigned long timeout = jiffies + HZ;
 724         int busy = 0;
 725
 726         if (slcan_devs == NULL)
 727                 return;
 728
 729         /* First of all: check for active disciplines and hangup them.
 730          */
 731         do {
 732                 if (busy)
 733                         msleep_interruptible(100);
 734
 735                 busy = 0;
 736                 for (i = 0; i < maxdev; i++) {
 737                         dev = slcan_devs[i];
 738                         if (!dev)
 739                                 continue;
 740                         sl = netdev_priv(dev);
 741                         spin_lock_bh(&sl->lock);
 742                         if (sl->tty) {
 743                                 busy++;
 744                                 tty_hangup(sl->tty);
 745                         }
 746                         spin_unlock_bh(&sl->lock);
 747                 }
 748         } while (busy && time_before(jiffies, timeout));
 749
 750         /* FIXME: hangup is async so we should wait when doing this second
 751            phase */
 752
 753         for (i = 0; i < maxdev; i++) {
 754                 dev = slcan_devs[i];
 755                 if (!dev)
 756                         continue;
 757                 slcan_devs[i] = NULL;
 758
 759                 sl = netdev_priv(dev);
 760                 if (sl->tty) {
 761                         printk(KERN_ERR "%s: tty discipline still running\n",
 762                                dev->name);
 763                         /* Intentionally leak the control block. */
 764                         dev->destructor = NULL;
 765                 }
 766
 767                 unregister_netdev(dev);
 768         }
 769
 770         kfree(slcan_devs);
 771         slcan_devs = NULL;
 772
 773         i = tty_unregister_ldisc(N_SLCAN);
 774         if (i)
 775                 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
 776 }
 777
 778 module_init(slcan_init);
 779 module_exit(slcan_exit);