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, 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
  24  *
  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
  36  * DAMAGE.
  37  *
  38  */
  39
  40 #include <linux/module.h>
  41 #include <linux/moduleparam.h>
  42
  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/workqueue.h>
  58 #include <linux/can.h>
  59 #include <linux/can/skb.h>
  60
  61 static __initconst const char banner[] =
  62         KERN_INFO "slcan: serial line CAN interface driver\n";
  63
  64 MODULE_ALIAS_LDISC(N_SLCAN);
  65 MODULE_DESCRIPTION("serial line CAN interface");
  66 MODULE_LICENSE("GPL");
  67 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
  68
  69 #define SLCAN_MAGIC 0x53CA
  70
  71 static int maxdev = 10;         /* MAX number of SLCAN channels;
  72                                    This can be overridden with
  73                                    insmod slcan.ko maxdev=nnn   */
  74 module_param(maxdev, int, 0);
  75 MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
  76
  77 /* maximum rx buffer len: extended CAN frame with timestamp */
  78 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
  79
  80 #define SLC_CMD_LEN 1
  81 #define SLC_SFF_ID_LEN 3
  82 #define SLC_EFF_ID_LEN 8
  83
  84 struct slcan {
  85         int                     magic;
  86
  87         /* Various fields. */
  88         struct tty_struct       *tty;           /* ptr to TTY structure      */
  89         struct net_device       *dev;           /* easy for intr handling    */
  90         spinlock_t              lock;
  91         struct work_struct      tx_work;        /* Flushes transmit buffer   */
  92
  93         /* These are pointers to the malloc()ed frame buffers. */
  94         unsigned char           rbuff[SLC_MTU]; /* receiver buffer           */
  95         int                     rcount;         /* received chars counter    */
  96         unsigned char           xbuff[SLC_MTU]; /* transmitter buffer        */
  97         unsigned char           *xhead;         /* pointer to next XMIT byte */
  98         int                     xleft;          /* bytes left in XMIT queue  */
  99
 100         unsigned long           flags;          /* Flag values/ mode etc     */
 101 #define SLF_INUSE               0               /* Channel in use            */
 102 #define SLF_ERROR               1               /* Parity, etc. error        */
 103 };
 104
 105 static struct net_device **slcan_devs;
 106
 107  /************************************************************************
 108   *                     SLCAN ENCAPSULATION FORMAT                       *
 109   ************************************************************************/
 110
 111 /*
 112  * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
 113  * frame format) a data length code (can_dlc) which can be from 0 to 8
 114  * and up to <can_dlc> data bytes as payload.
 115  * Additionally a CAN frame may become a remote transmission frame if the
 116  * RTR-bit is set. This causes another ECU to send a CAN frame with the
 117  * given can_id.
 118  *
 119  * The SLCAN ASCII representation of these different frame types is:
 120  * <type> <id> <dlc> <data>*
 121  *
 122  * Extended frames (29 bit) are defined by capital characters in the type.
 123  * RTR frames are defined as 'r' types - normal frames have 't' type:
 124  * t => 11 bit data frame
 125  * r => 11 bit RTR frame
 126  * T => 29 bit data frame
 127  * R => 29 bit RTR frame
 128  *
 129  * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
 130  * The <dlc> is a one byte ASCII number ('0' - '8')
 131  * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
 132  *
 133  * Examples:
 134  *
 135  * t1230 : can_id 0x123, can_dlc 0, no data
 136  * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
 137  * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
 138  * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
 139  *
 140  */
 141
 142  /************************************************************************
 143   *                     STANDARD SLCAN DECAPSULATION                     *
 144   ************************************************************************/
 145
 146 /* Send one completely decapsulated can_frame to the network layer */
 147 static void slc_bump(struct slcan *sl)
 148 {
 149         struct sk_buff *skb;
 150         struct can_frame cf;
 151         int i, tmp;
 152         u32 tmpid;
 153         char *cmd = sl->rbuff;
 154
 155         cf.can_id = 0;
 156
 157         switch (*cmd) {
 158         case 'r':
 159                 cf.can_id = CAN_RTR_FLAG;
 160                 /* fallthrough */
 161         case 't':
 162                 /* store dlc ASCII value and terminate SFF CAN ID string */
 163                 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
 164                 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
 165                 /* point to payload data behind the dlc */
 166                 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
 167                 break;
 168         case 'R':
 169                 cf.can_id = CAN_RTR_FLAG;
 170                 /* fallthrough */
 171         case 'T':
 172                 cf.can_id |= CAN_EFF_FLAG;
 173                 /* store dlc ASCII value and terminate EFF CAN ID string */
 174                 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
 175                 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
 176                 /* point to payload data behind the dlc */
 177                 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
 178                 break;
 179         default:
 180                 return;
 181         }
 182
 183         if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
 184                 return;
 185
 186         cf.can_id |= tmpid;
 187
 188         /* get can_dlc from sanitized ASCII value */
 189         if (cf.can_dlc >= '0' && cf.can_dlc < '9')
 190                 cf.can_dlc -= '0';
 191         else
 192                 return;
 193
 194         *(u64 *) (&cf.data) = 0; /* clear payload */
 195
 196         /* RTR frames may have a dlc > 0 but they never have any data bytes */
 197         if (!(cf.can_id & CAN_RTR_FLAG)) {
 198                 for (i = 0; i < cf.can_dlc; i++) {
 199                         tmp = hex_to_bin(*cmd++);
 200                         if (tmp < 0)
 201                                 return;
 202                         cf.data[i] = (tmp << 4);
 203                         tmp = hex_to_bin(*cmd++);
 204                         if (tmp < 0)
 205                                 return;
 206                         cf.data[i] |= tmp;
 207                 }
 208         }
 209
 210         skb = dev_alloc_skb(sizeof(struct can_frame) +
 211                             sizeof(struct can_skb_priv));
 212         if (!skb)
 213                 return;
 214
 215         skb->dev = sl->dev;
 216         skb->protocol = htons(ETH_P_CAN);
 217         skb->pkt_type = PACKET_BROADCAST;
 218         skb->ip_summed = CHECKSUM_UNNECESSARY;
 219
 220         can_skb_reserve(skb);
 221         can_skb_prv(skb)->ifindex = sl->dev->ifindex;
 222
 223         memcpy(skb_put(skb, sizeof(struct can_frame)),
 224                &cf, sizeof(struct can_frame));
 225         netif_rx_ni(skb);
 226
 227         sl->dev->stats.rx_packets++;
 228         sl->dev->stats.rx_bytes += cf.can_dlc;
 229 }
 230
 231 /* parse tty input stream */
 232 static void slcan_unesc(struct slcan *sl, unsigned char s)
 233 {
 234         if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
 235                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 236                     (sl->rcount > 4))  {
 237                         slc_bump(sl);
 238                 }
 239                 sl->rcount = 0;
 240         } else {
 241                 if (!test_bit(SLF_ERROR, &sl->flags))  {
 242                         if (sl->rcount < SLC_MTU)  {
 243                                 sl->rbuff[sl->rcount++] = s;
 244                                 return;
 245                         } else {
 246                                 sl->dev->stats.rx_over_errors++;
 247                                 set_bit(SLF_ERROR, &sl->flags);
 248                         }
 249                 }
 250         }
 251 }
 252
 253  /************************************************************************
 254   *                     STANDARD SLCAN ENCAPSULATION                     *
 255   ************************************************************************/
 256
 257 /* Encapsulate one can_frame and stuff into a TTY queue. */
 258 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
 259 {
 260         int actual, i;
 261         unsigned char *pos;
 262         unsigned char *endpos;
 263         canid_t id = cf->can_id;
 264
 265         pos = sl->xbuff;
 266
 267         if (cf->can_id & CAN_RTR_FLAG)
 268                 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
 269         else
 270                 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
 271
 272         /* determine number of chars for the CAN-identifier */
 273         if (cf->can_id & CAN_EFF_FLAG) {
 274                 id &= CAN_EFF_MASK;
 275                 endpos = pos + SLC_EFF_ID_LEN;
 276         } else {
 277                 *pos |= 0x20; /* convert R/T to lower case for SFF */
 278                 id &= CAN_SFF_MASK;
 279                 endpos = pos + SLC_SFF_ID_LEN;
 280         }
 281
 282         /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
 283         pos++;
 284         while (endpos >= pos) {
 285                 *endpos-- = hex_asc_upper[id & 0xf];
 286                 id >>= 4;
 287         }
 288
 289         pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
 290
 291         *pos++ = cf->can_dlc + '0';
 292
 293         /* RTR frames may have a dlc > 0 but they never have any data bytes */
 294         if (!(cf->can_id & CAN_RTR_FLAG)) {
 295                 for (i = 0; i < cf->can_dlc; i++)
 296                         pos = hex_byte_pack_upper(pos, cf->data[i]);
 297         }
 298
 299         *pos++ = '\r';
 300
 301         /* Order of next two lines is *very* important.
 302          * When we are sending a little amount of data,
 303          * the transfer may be completed inside the ops->write()
 304          * routine, because it's running with interrupts enabled.
 305          * In this case we *never* got WRITE_WAKEUP event,
 306          * if we did not request it before write operation.
 307          *       14 Oct 1994  Dmitry Gorodchanin.
 308          */
 309         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 310         actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
 311         sl->xleft = (pos - sl->xbuff) - actual;
 312         sl->xhead = sl->xbuff + actual;
 313         sl->dev->stats.tx_bytes += cf->can_dlc;
 314 }
 315
 316 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 317 static void slcan_transmit(struct work_struct *work)
 318 {
 319         struct slcan *sl = container_of(work, struct slcan, tx_work);
 320         int actual;
 321
 322         spin_lock_bh(&sl->lock);
 323         /* First make sure we're connected. */
 324         if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
 325                 spin_unlock_bh(&sl->lock);
 326                 return;
 327         }
 328
 329         if (sl->xleft <= 0)  {
 330                 /* Now serial buffer is almost free & we can start
 331                  * transmission of another packet */
 332                 sl->dev->stats.tx_packets++;
 333                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 334                 spin_unlock_bh(&sl->lock);
 335                 netif_wake_queue(sl->dev);
 336                 return;
 337         }
 338
 339         actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
 340         sl->xleft -= actual;
 341         sl->xhead += actual;
 342         spin_unlock_bh(&sl->lock);
 343 }
 344
 345 /*
 346  * Called by the driver when there's room for more data.
 347  * Schedule the transmit.
 348  */
 349 static void slcan_write_wakeup(struct tty_struct *tty)
 350 {
 351         struct slcan *sl = tty->disc_data;
 352
 353         schedule_work(&sl->tx_work);
 354 }
 355
 356 /* Send a can_frame to a TTY queue. */
 357 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
 358 {
 359         struct slcan *sl = netdev_priv(dev);
 360
 361         if (skb->len != sizeof(struct can_frame))
 362                 goto out;
 363
 364         spin_lock(&sl->lock);
 365         if (!netif_running(dev))  {
 366                 spin_unlock(&sl->lock);
 367                 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
 368                 goto out;
 369         }
 370         if (sl->tty == NULL) {
 371                 spin_unlock(&sl->lock);
 372                 goto out;
 373         }
 374
 375         netif_stop_queue(sl->dev);
 376         slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
 377         spin_unlock(&sl->lock);
 378
 379 out:
 380         kfree_skb(skb);
 381         return NETDEV_TX_OK;
 382 }
 383
 384
 385 /******************************************
 386  *   Routines looking at netdevice side.
 387  ******************************************/
 388
 389 /* Netdevice UP -> DOWN routine */
 390 static int slc_close(struct net_device *dev)
 391 {
 392         struct slcan *sl = netdev_priv(dev);
 393
 394         spin_lock_bh(&sl->lock);
 395         if (sl->tty) {
 396                 /* TTY discipline is running. */
 397                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 398         }
 399         netif_stop_queue(dev);
 400         sl->rcount   = 0;
 401         sl->xleft    = 0;
 402         spin_unlock_bh(&sl->lock);
 403
 404         return 0;
 405 }
 406
 407 /* Netdevice DOWN -> UP routine */
 408 static int slc_open(struct net_device *dev)
 409 {
 410         struct slcan *sl = netdev_priv(dev);
 411
 412         if (sl->tty == NULL)
 413                 return -ENODEV;
 414
 415         sl->flags &= (1 << SLF_INUSE);
 416         netif_start_queue(dev);
 417         return 0;
 418 }
 419
 420 /* Hook the destructor so we can free slcan devs at the right point in time */
 421 static void slc_free_netdev(struct net_device *dev)
 422 {
 423         int i = dev->base_addr;
 424         free_netdev(dev);
 425         slcan_devs[i] = NULL;
 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 };
 433
 434 static void slc_setup(struct net_device *dev)
 435 {
 436         dev->netdev_ops         = &slc_netdev_ops;
 437         dev->destructor         = slc_free_netdev;
 438
 439         dev->hard_header_len    = 0;
 440         dev->addr_len           = 0;
 441         dev->tx_queue_len       = 10;
 442
 443         dev->mtu                = sizeof(struct can_frame);
 444         dev->type               = ARPHRD_CAN;
 445
 446         /* New-style flags. */
 447         dev->flags              = IFF_NOARP;
 448         dev->features           = NETIF_F_HW_CSUM;
 449 }
 450
 451 /******************************************
 452   Routines looking at TTY side.
 453  ******************************************/
 454
 455 /*
 456  * Handle the 'receiver data ready' interrupt.
 457  * This function is called by the 'tty_io' module in the kernel when
 458  * a block of SLCAN data has been received, which can now be decapsulated
 459  * and sent on to some IP layer for further processing. This will not
 460  * be re-entered while running but other ldisc functions may be called
 461  * in parallel
 462  */
 463
 464 static void slcan_receive_buf(struct tty_struct *tty,
 465                               const unsigned char *cp, char *fp, int count)
 466 {
 467         struct slcan *sl = (struct slcan *) tty->disc_data;
 468
 469         if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
 470                 return;
 471
 472         /* Read the characters out of the buffer */
 473         while (count--) {
 474                 if (fp && *fp++) {
 475                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 476                                 sl->dev->stats.rx_errors++;
 477                         cp++;
 478                         continue;
 479                 }
 480                 slcan_unesc(sl, *cp++);
 481         }
 482 }
 483
 484 /************************************
 485  *  slcan_open helper routines.
 486  ************************************/
 487
 488 /* Collect hanged up channels */
 489 static void slc_sync(void)
 490 {
 491         int i;
 492         struct net_device *dev;
 493         struct slcan      *sl;
 494
 495         for (i = 0; i < maxdev; i++) {
 496                 dev = slcan_devs[i];
 497                 if (dev == NULL)
 498                         break;
 499
 500                 sl = netdev_priv(dev);
 501                 if (sl->tty)
 502                         continue;
 503                 if (dev->flags & IFF_UP)
 504                         dev_close(dev);
 505         }
 506 }
 507
 508 /* Find a free SLCAN channel, and link in this `tty' line. */
 509 static struct slcan *slc_alloc(dev_t line)
 510 {
 511         int i;
 512         char name[IFNAMSIZ];
 513         struct net_device *dev = NULL;
 514         struct slcan       *sl;
 515
 516         for (i = 0; i < maxdev; i++) {
 517                 dev = slcan_devs[i];
 518                 if (dev == NULL)
 519                         break;
 520
 521         }
 522
 523         /* Sorry, too many, all slots in use */
 524         if (i >= maxdev)
 525                 return NULL;
 526
 527         sprintf(name, "slcan%d", i);
 528         dev = alloc_netdev(sizeof(*sl), name, slc_setup);
 529         if (!dev)
 530                 return NULL;
 531
 532         dev->base_addr  = i;
 533         sl = netdev_priv(dev);
 534
 535         /* Initialize channel control data */
 536         sl->magic = SLCAN_MAGIC;
 537         sl->dev = dev;
 538         spin_lock_init(&sl->lock);
 539         INIT_WORK(&sl->tx_work, slcan_transmit);
 540         slcan_devs[i] = dev;
 541
 542         return sl;
 543 }
 544
 545 /*
 546  * Open the high-level part of the SLCAN channel.
 547  * This function is called by the TTY module when the
 548  * SLCAN line discipline is called for.  Because we are
 549  * sure the tty line exists, we only have to link it to
 550  * a free SLCAN channel...
 551  *
 552  * Called in process context serialized from other ldisc calls.
 553  */
 554
 555 static int slcan_open(struct tty_struct *tty)
 556 {
 557         struct slcan *sl;
 558         int err;
 559
 560         if (!capable(CAP_NET_ADMIN))
 561                 return -EPERM;
 562
 563         if (tty->ops->write == NULL)
 564                 return -EOPNOTSUPP;
 565
 566         /* RTnetlink lock is misused here to serialize concurrent
 567            opens of slcan channels. There are better ways, but it is
 568            the simplest one.
 569          */
 570         rtnl_lock();
 571
 572         /* Collect hanged up channels. */
 573         slc_sync();
 574
 575         sl = tty->disc_data;
 576
 577         err = -EEXIST;
 578         /* First make sure we're not already connected. */
 579         if (sl && sl->magic == SLCAN_MAGIC)
 580                 goto err_exit;
 581
 582         /* OK.  Find a free SLCAN channel to use. */
 583         err = -ENFILE;
 584         sl = slc_alloc(tty_devnum(tty));
 585         if (sl == NULL)
 586                 goto err_exit;
 587
 588         sl->tty = tty;
 589         tty->disc_data = sl;
 590
 591         if (!test_bit(SLF_INUSE, &sl->flags)) {
 592                 /* Perform the low-level SLCAN initialization. */
 593                 sl->rcount   = 0;
 594                 sl->xleft    = 0;
 595
 596                 set_bit(SLF_INUSE, &sl->flags);
 597
 598                 err = register_netdevice(sl->dev);
 599                 if (err)
 600                         goto err_free_chan;
 601         }
 602
 603         /* Done.  We have linked the TTY line to a channel. */
 604         rtnl_unlock();
 605         tty->receive_room = 65536;      /* We don't flow control */
 606
 607         /* TTY layer expects 0 on success */
 608         return 0;
 609
 610 err_free_chan:
 611         sl->tty = NULL;
 612         tty->disc_data = NULL;
 613         clear_bit(SLF_INUSE, &sl->flags);
 614
 615 err_exit:
 616         rtnl_unlock();
 617
 618         /* Count references from TTY module */
 619         return err;
 620 }
 621
 622 /*
 623  * Close down a SLCAN channel.
 624  * This means flushing out any pending queues, and then returning. This
 625  * call is serialized against other ldisc functions.
 626  *
 627  * We also use this method for a hangup event.
 628  */
 629
 630 static void slcan_close(struct tty_struct *tty)
 631 {
 632         struct slcan *sl = (struct slcan *) tty->disc_data;
 633
 634         /* First make sure we're connected. */
 635         if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
 636                 return;
 637
 638         spin_lock_bh(&sl->lock);
 639         tty->disc_data = NULL;
 640         sl->tty = NULL;
 641         spin_unlock_bh(&sl->lock);
 642
 643         flush_work(&sl->tx_work);
 644
 645         /* Flush network side */
 646         unregister_netdev(sl->dev);
 647         /* This will complete via sl_free_netdev */
 648 }
 649
 650 static int slcan_hangup(struct tty_struct *tty)
 651 {
 652         slcan_close(tty);
 653         return 0;
 654 }
 655
 656 /* Perform I/O control on an active SLCAN channel. */
 657 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
 658                        unsigned int cmd, unsigned long arg)
 659 {
 660         struct slcan *sl = (struct slcan *) tty->disc_data;
 661         unsigned int tmp;
 662
 663         /* First make sure we're connected. */
 664         if (!sl || sl->magic != SLCAN_MAGIC)
 665                 return -EINVAL;
 666
 667         switch (cmd) {
 668         case SIOCGIFNAME:
 669                 tmp = strlen(sl->dev->name) + 1;
 670                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
 671                         return -EFAULT;
 672                 return 0;
 673
 674         case SIOCSIFHWADDR:
 675                 return -EINVAL;
 676
 677         default:
 678                 return tty_mode_ioctl(tty, file, cmd, arg);
 679         }
 680 }
 681
 682 static struct tty_ldisc_ops slc_ldisc = {
 683         .owner          = THIS_MODULE,
 684         .magic          = TTY_LDISC_MAGIC,
 685         .name           = "slcan",
 686         .open           = slcan_open,
 687         .close          = slcan_close,
 688         .hangup         = slcan_hangup,
 689         .ioctl          = slcan_ioctl,
 690         .receive_buf    = slcan_receive_buf,
 691         .write_wakeup   = slcan_write_wakeup,
 692 };
 693
 694 static int __init slcan_init(void)
 695 {
 696         int status;
 697
 698         if (maxdev < 4)
 699                 maxdev = 4; /* Sanity */
 700
 701         printk(banner);
 702         printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
 703
 704         slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
 705         if (!slcan_devs)
 706                 return -ENOMEM;
 707
 708         /* Fill in our line protocol discipline, and register it */
 709         status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
 710         if (status)  {
 711                 printk(KERN_ERR "slcan: can't register line discipline\n");
 712                 kfree(slcan_devs);
 713         }
 714         return status;
 715 }
 716
 717 static void __exit slcan_exit(void)
 718 {
 719         int i;
 720         struct net_device *dev;
 721         struct slcan *sl;
 722         unsigned long timeout = jiffies + HZ;
 723         int busy = 0;
 724
 725         if (slcan_devs == NULL)
 726                 return;
 727
 728         /* First of all: check for active disciplines and hangup them.
 729          */
 730         do {
 731                 if (busy)
 732                         msleep_interruptible(100);
 733
 734                 busy = 0;
 735                 for (i = 0; i < maxdev; i++) {
 736                         dev = slcan_devs[i];
 737                         if (!dev)
 738                                 continue;
 739                         sl = netdev_priv(dev);
 740                         spin_lock_bh(&sl->lock);
 741                         if (sl->tty) {
 742                                 busy++;
 743                                 tty_hangup(sl->tty);
 744                         }
 745                         spin_unlock_bh(&sl->lock);
 746                 }
 747         } while (busy && time_before(jiffies, timeout));
 748
 749         /* FIXME: hangup is async so we should wait when doing this second
 750            phase */
 751
 752         for (i = 0; i < maxdev; i++) {
 753                 dev = slcan_devs[i];
 754                 if (!dev)
 755                         continue;
 756                 slcan_devs[i] = NULL;
 757
 758                 sl = netdev_priv(dev);
 759                 if (sl->tty) {
 760                         printk(KERN_ERR "%s: tty discipline still running\n",
 761                                dev->name);
 762                         /* Intentionally leak the control block. */
 763                         dev->destructor = NULL;
 764                 }
 765
 766                 unregister_netdev(dev);
 767         }
 768
 769         kfree(slcan_devs);
 770         slcan_devs = NULL;
 771
 772         i = tty_unregister_ldisc(N_SLCAN);
 773         if (i)
 774                 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
 775 }
 776
 777 module_init(slcan_init);
 778 module_exit(slcan_exit);