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 static __initconst const char banner[] =
  60         KERN_INFO "slcan: serial line CAN interface driver\n";
  61
  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>");
  66
  67 #define SLCAN_MAGIC 0x53CA
  68
  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");
  74
  75 /* maximum rx buffer len: extended CAN frame with timestamp */
  76 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
  77
  78 #define SLC_CMD_LEN 1
  79 #define SLC_SFF_ID_LEN 3
  80 #define SLC_EFF_ID_LEN 8
  81
  82 struct slcan {
  83         int                     magic;
  84
  85         /* Various fields. */
  86         struct tty_struct       *tty;           /* ptr to TTY structure      */
  87         struct net_device       *dev;           /* easy for intr handling    */
  88         spinlock_t              lock;
  89         struct work_struct      tx_work;        /* Flushes transmit buffer   */
  90
  91         /* These are pointers to the malloc()ed frame buffers. */
  92         unsigned char           rbuff[SLC_MTU]; /* receiver buffer           */
  93         int                     rcount;         /* received chars counter    */
  94         unsigned char           xbuff[SLC_MTU]; /* transmitter buffer        */
  95         unsigned char           *xhead;         /* pointer to next XMIT byte */
  96         int                     xleft;          /* bytes left in XMIT queue  */
  97
  98         unsigned long           flags;          /* Flag values/ mode etc     */
  99 #define SLF_INUSE               0               /* Channel in use            */
 100 #define SLF_ERROR               1               /* Parity, etc. error        */
 101 };
 102
 103 static struct net_device **slcan_devs;
 104
 105  /************************************************************************
 106   *                     SLCAN ENCAPSULATION FORMAT                       *
 107   ************************************************************************/
 108
 109 /*
 110  * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
 111  * frame format) a data length code (can_dlc) which can be from 0 to 8
 112  * and up to <can_dlc> data bytes as payload.
 113  * Additionally a CAN frame may become a remote transmission frame if the
 114  * RTR-bit is set. This causes another ECU to send a CAN frame with the
 115  * given can_id.
 116  *
 117  * The SLCAN ASCII representation of these different frame types is:
 118  * <type> <id> <dlc> <data>*
 119  *
 120  * Extended frames (29 bit) are defined by capital characters in the type.
 121  * RTR frames are defined as 'r' types - normal frames have 't' type:
 122  * t => 11 bit data frame
 123  * r => 11 bit RTR frame
 124  * T => 29 bit data frame
 125  * R => 29 bit RTR frame
 126  *
 127  * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
 128  * The <dlc> is a one byte ASCII number ('0' - '8')
 129  * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
 130  *
 131  * Examples:
 132  *
 133  * t1230 : can_id 0x123, can_dlc 0, no data
 134  * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
 135  * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
 136  * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
 137  *
 138  */
 139
 140  /************************************************************************
 141   *                     STANDARD SLCAN DECAPSULATION                     *
 142   ************************************************************************/
 143
 144 /* Send one completely decapsulated can_frame to the network layer */
 145 static void slc_bump(struct slcan *sl)
 146 {
 147         struct sk_buff *skb;
 148         struct can_frame cf;
 149         int i, tmp;
 150         u32 tmpid;
 151         char *cmd = sl->rbuff;
 152
 153         cf.can_id = 0;
 154
 155         switch (*cmd) {
 156         case 'r':
 157                 cf.can_id = CAN_RTR_FLAG;
 158                 /* fallthrough */
 159         case 't':
 160                 /* store dlc ASCII value and terminate SFF CAN ID string */
 161                 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
 162                 sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
 163                 /* point to payload data behind the dlc */
 164                 cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
 165                 break;
 166         case 'R':
 167                 cf.can_id = CAN_RTR_FLAG;
 168                 /* fallthrough */
 169         case 'T':
 170                 cf.can_id |= CAN_EFF_FLAG;
 171                 /* store dlc ASCII value and terminate EFF CAN ID string */
 172                 cf.can_dlc = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
 173                 sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
 174                 /* point to payload data behind the dlc */
 175                 cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
 176                 break;
 177         default:
 178                 return;
 179         }
 180
 181         if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
 182                 return;
 183
 184         cf.can_id |= tmpid;
 185
 186         /* get can_dlc from sanitized ASCII value */
 187         if (cf.can_dlc >= '0' && cf.can_dlc < '9')
 188                 cf.can_dlc -= '0';
 189         else
 190                 return;
 191
 192         *(u64 *) (&cf.data) = 0; /* clear payload */
 193
 194         /* RTR frames may have a dlc > 0 but they never have any data bytes */
 195         if (!(cf.can_id & CAN_RTR_FLAG)) {
 196                 for (i = 0; i < cf.can_dlc; i++) {
 197                         tmp = hex_to_bin(*cmd++);
 198                         if (tmp < 0)
 199                                 return;
 200                         cf.data[i] = (tmp << 4);
 201                         tmp = hex_to_bin(*cmd++);
 202                         if (tmp < 0)
 203                                 return;
 204                         cf.data[i] |= tmp;
 205                 }
 206         }
 207
 208         skb = dev_alloc_skb(sizeof(struct can_frame) +
 209                             sizeof(struct can_skb_priv));
 210         if (!skb)
 211                 return;
 212
 213         skb->dev = sl->dev;
 214         skb->protocol = htons(ETH_P_CAN);
 215         skb->pkt_type = PACKET_BROADCAST;
 216         skb->ip_summed = CHECKSUM_UNNECESSARY;
 217
 218         can_skb_reserve(skb);
 219         can_skb_prv(skb)->ifindex = sl->dev->ifindex;
 220
 221         memcpy(skb_put(skb, sizeof(struct can_frame)),
 222                &cf, sizeof(struct can_frame));
 223         netif_rx_ni(skb);
 224
 225         sl->dev->stats.rx_packets++;
 226         sl->dev->stats.rx_bytes += cf.can_dlc;
 227 }
 228
 229 /* parse tty input stream */
 230 static void slcan_unesc(struct slcan *sl, unsigned char s)
 231 {
 232         if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
 233                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 234                     (sl->rcount > 4))  {
 235                         slc_bump(sl);
 236                 }
 237                 sl->rcount = 0;
 238         } else {
 239                 if (!test_bit(SLF_ERROR, &sl->flags))  {
 240                         if (sl->rcount < SLC_MTU)  {
 241                                 sl->rbuff[sl->rcount++] = s;
 242                                 return;
 243                         } else {
 244                                 sl->dev->stats.rx_over_errors++;
 245                                 set_bit(SLF_ERROR, &sl->flags);
 246                         }
 247                 }
 248         }
 249 }
 250
 251  /************************************************************************
 252   *                     STANDARD SLCAN ENCAPSULATION                     *
 253   ************************************************************************/
 254
 255 /* Encapsulate one can_frame and stuff into a TTY queue. */
 256 static void slc_encaps(struct slcan *sl, struct can_frame *cf)
 257 {
 258         int actual, i;
 259         unsigned char *pos;
 260         unsigned char *endpos;
 261         canid_t id = cf->can_id;
 262
 263         pos = sl->xbuff;
 264
 265         if (cf->can_id & CAN_RTR_FLAG)
 266                 *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */
 267         else
 268                 *pos = 'T'; /* becomes 't' in standard frame format (SSF) */
 269
 270         /* determine number of chars for the CAN-identifier */
 271         if (cf->can_id & CAN_EFF_FLAG) {
 272                 id &= CAN_EFF_MASK;
 273                 endpos = pos + SLC_EFF_ID_LEN;
 274         } else {
 275                 *pos |= 0x20; /* convert R/T to lower case for SFF */
 276                 id &= CAN_SFF_MASK;
 277                 endpos = pos + SLC_SFF_ID_LEN;
 278         }
 279
 280         /* build 3 (SFF) or 8 (EFF) digit CAN identifier */
 281         pos++;
 282         while (endpos >= pos) {
 283                 *endpos-- = hex_asc_upper[id & 0xf];
 284                 id >>= 4;
 285         }
 286
 287         pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
 288
 289         *pos++ = cf->can_dlc + '0';
 290
 291         /* RTR frames may have a dlc > 0 but they never have any data bytes */
 292         if (!(cf->can_id & CAN_RTR_FLAG)) {
 293                 for (i = 0; i < cf->can_dlc; i++)
 294                         pos = hex_byte_pack_upper(pos, cf->data[i]);
 295         }
 296
 297         *pos++ = '\r';
 298
 299         /* Order of next two lines is *very* important.
 300          * When we are sending a little amount of data,
 301          * the transfer may be completed inside the ops->write()
 302          * routine, because it's running with interrupts enabled.
 303          * In this case we *never* got WRITE_WAKEUP event,
 304          * if we did not request it before write operation.
 305          *       14 Oct 1994  Dmitry Gorodchanin.
 306          */
 307         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 308         actual = sl->tty->ops->write(sl->tty, sl->xbuff, pos - sl->xbuff);
 309         sl->xleft = (pos - sl->xbuff) - actual;
 310         sl->xhead = sl->xbuff + actual;
 311         sl->dev->stats.tx_bytes += cf->can_dlc;
 312 }
 313
 314 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 315 static void slcan_transmit(struct work_struct *work)
 316 {
 317         struct slcan *sl = container_of(work, struct slcan, tx_work);
 318         int actual;
 319
 320         spin_lock_bh(&sl->lock);
 321         /* First make sure we're connected. */
 322         if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
 323                 spin_unlock_bh(&sl->lock);
 324                 return;
 325         }
 326
 327         if (sl->xleft <= 0)  {
 328                 /* Now serial buffer is almost free & we can start
 329                  * transmission of another packet */
 330                 sl->dev->stats.tx_packets++;
 331                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 332                 spin_unlock_bh(&sl->lock);
 333                 netif_wake_queue(sl->dev);
 334                 return;
 335         }
 336
 337         actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
 338         sl->xleft -= actual;
 339         sl->xhead += actual;
 340         spin_unlock_bh(&sl->lock);
 341 }
 342
 343 /*
 344  * Called by the driver when there's room for more data.
 345  * Schedule the transmit.
 346  */
 347 static void slcan_write_wakeup(struct tty_struct *tty)
 348 {
 349         struct slcan *sl = tty->disc_data;
 350
 351         schedule_work(&sl->tx_work);
 352 }
 353
 354 /* Send a can_frame to a TTY queue. */
 355 static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
 356 {
 357         struct slcan *sl = netdev_priv(dev);
 358
 359         if (skb->len != sizeof(struct can_frame))
 360                 goto out;
 361
 362         spin_lock(&sl->lock);
 363         if (!netif_running(dev))  {
 364                 spin_unlock(&sl->lock);
 365                 printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
 366                 goto out;
 367         }
 368         if (sl->tty == NULL) {
 369                 spin_unlock(&sl->lock);
 370                 goto out;
 371         }
 372
 373         netif_stop_queue(sl->dev);
 374         slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
 375         spin_unlock(&sl->lock);
 376
 377 out:
 378         kfree_skb(skb);
 379         return NETDEV_TX_OK;
 380 }
 381
 382
 383 /******************************************
 384  *   Routines looking at netdevice side.
 385  ******************************************/
 386
 387 /* Netdevice UP -> DOWN routine */
 388 static int slc_close(struct net_device *dev)
 389 {
 390         struct slcan *sl = netdev_priv(dev);
 391
 392         spin_lock_bh(&sl->lock);
 393         if (sl->tty) {
 394                 /* TTY discipline is running. */
 395                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 396         }
 397         netif_stop_queue(dev);
 398         sl->rcount   = 0;
 399         sl->xleft    = 0;
 400         spin_unlock_bh(&sl->lock);
 401
 402         return 0;
 403 }
 404
 405 /* Netdevice DOWN -> UP routine */
 406 static int slc_open(struct net_device *dev)
 407 {
 408         struct slcan *sl = netdev_priv(dev);
 409
 410         if (sl->tty == NULL)
 411                 return -ENODEV;
 412
 413         sl->flags &= (1 << SLF_INUSE);
 414         netif_start_queue(dev);
 415         return 0;
 416 }
 417
 418 /* Hook the destructor so we can free slcan devs at the right point in time */
 419 static void slc_free_netdev(struct net_device *dev)
 420 {
 421         int i = dev->base_addr;
 422         free_netdev(dev);
 423         slcan_devs[i] = NULL;
 424 }
 425
 426 static int slcan_change_mtu(struct net_device *dev, int new_mtu)
 427 {
 428         return -EINVAL;
 429 }
 430
 431 static const struct net_device_ops slc_netdev_ops = {
 432         .ndo_open               = slc_open,
 433         .ndo_stop               = slc_close,
 434         .ndo_start_xmit         = slc_xmit,
 435         .ndo_change_mtu         = slcan_change_mtu,
 436 };
 437
 438 static void slc_setup(struct net_device *dev)
 439 {
 440         dev->netdev_ops         = &slc_netdev_ops;
 441         dev->destructor         = slc_free_netdev;
 442
 443         dev->hard_header_len    = 0;
 444         dev->addr_len           = 0;
 445         dev->tx_queue_len       = 10;
 446
 447         dev->mtu                = sizeof(struct can_frame);
 448         dev->type               = ARPHRD_CAN;
 449
 450         /* New-style flags. */
 451         dev->flags              = IFF_NOARP;
 452         dev->features           = NETIF_F_HW_CSUM;
 453 }
 454
 455 /******************************************
 456   Routines looking at TTY side.
 457  ******************************************/
 458
 459 /*
 460  * Handle the 'receiver data ready' interrupt.
 461  * This function is called by the 'tty_io' module in the kernel when
 462  * a block of SLCAN data has been received, which can now be decapsulated
 463  * and sent on to some IP layer for further processing. This will not
 464  * be re-entered while running but other ldisc functions may be called
 465  * in parallel
 466  */
 467
 468 static void slcan_receive_buf(struct tty_struct *tty,
 469                               const unsigned char *cp, char *fp, int count)
 470 {
 471         struct slcan *sl = (struct slcan *) tty->disc_data;
 472
 473         if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
 474                 return;
 475
 476         /* Read the characters out of the buffer */
 477         while (count--) {
 478                 if (fp && *fp++) {
 479                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 480                                 sl->dev->stats.rx_errors++;
 481                         cp++;
 482                         continue;
 483                 }
 484                 slcan_unesc(sl, *cp++);
 485         }
 486 }
 487
 488 /************************************
 489  *  slcan_open helper routines.
 490  ************************************/
 491
 492 /* Collect hanged up channels */
 493 static void slc_sync(void)
 494 {
 495         int i;
 496         struct net_device *dev;
 497         struct slcan      *sl;
 498
 499         for (i = 0; i < maxdev; i++) {
 500                 dev = slcan_devs[i];
 501                 if (dev == NULL)
 502                         break;
 503
 504                 sl = netdev_priv(dev);
 505                 if (sl->tty)
 506                         continue;
 507                 if (dev->flags & IFF_UP)
 508                         dev_close(dev);
 509         }
 510 }
 511
 512 /* Find a free SLCAN channel, and link in this `tty' line. */
 513 static struct slcan *slc_alloc(dev_t line)
 514 {
 515         int i;
 516         char name[IFNAMSIZ];
 517         struct net_device *dev = NULL;
 518         struct slcan       *sl;
 519
 520         for (i = 0; i < maxdev; i++) {
 521                 dev = slcan_devs[i];
 522                 if (dev == NULL)
 523                         break;
 524
 525         }
 526
 527         /* Sorry, too many, all slots in use */
 528         if (i >= maxdev)
 529                 return NULL;
 530
 531         sprintf(name, "slcan%d", i);
 532         dev = alloc_netdev(sizeof(*sl), name, slc_setup);
 533         if (!dev)
 534                 return NULL;
 535
 536         dev->base_addr  = i;
 537         sl = netdev_priv(dev);
 538
 539         /* Initialize channel control data */
 540         sl->magic = SLCAN_MAGIC;
 541         sl->dev = dev;
 542         spin_lock_init(&sl->lock);
 543         INIT_WORK(&sl->tx_work, slcan_transmit);
 544         slcan_devs[i] = dev;
 545
 546         return sl;
 547 }
 548
 549 /*
 550  * Open the high-level part of the SLCAN channel.
 551  * This function is called by the TTY module when the
 552  * SLCAN line discipline is called for.  Because we are
 553  * sure the tty line exists, we only have to link it to
 554  * a free SLCAN channel...
 555  *
 556  * Called in process context serialized from other ldisc calls.
 557  */
 558
 559 static int slcan_open(struct tty_struct *tty)
 560 {
 561         struct slcan *sl;
 562         int err;
 563
 564         if (!capable(CAP_NET_ADMIN))
 565                 return -EPERM;
 566
 567         if (tty->ops->write == NULL)
 568                 return -EOPNOTSUPP;
 569
 570         /* RTnetlink lock is misused here to serialize concurrent
 571            opens of slcan channels. There are better ways, but it is
 572            the simplest one.
 573          */
 574         rtnl_lock();
 575
 576         /* Collect hanged up channels. */
 577         slc_sync();
 578
 579         sl = tty->disc_data;
 580
 581         err = -EEXIST;
 582         /* First make sure we're not already connected. */
 583         if (sl && sl->magic == SLCAN_MAGIC)
 584                 goto err_exit;
 585
 586         /* OK.  Find a free SLCAN channel to use. */
 587         err = -ENFILE;
 588         sl = slc_alloc(tty_devnum(tty));
 589         if (sl == NULL)
 590                 goto err_exit;
 591
 592         sl->tty = tty;
 593         tty->disc_data = sl;
 594
 595         if (!test_bit(SLF_INUSE, &sl->flags)) {
 596                 /* Perform the low-level SLCAN initialization. */
 597                 sl->rcount   = 0;
 598                 sl->xleft    = 0;
 599
 600                 set_bit(SLF_INUSE, &sl->flags);
 601
 602                 err = register_netdevice(sl->dev);
 603                 if (err)
 604                         goto err_free_chan;
 605         }
 606
 607         /* Done.  We have linked the TTY line to a channel. */
 608         rtnl_unlock();
 609         tty->receive_room = 65536;      /* We don't flow control */
 610
 611         /* TTY layer expects 0 on success */
 612         return 0;
 613
 614 err_free_chan:
 615         sl->tty = NULL;
 616         tty->disc_data = NULL;
 617         clear_bit(SLF_INUSE, &sl->flags);
 618
 619 err_exit:
 620         rtnl_unlock();
 621
 622         /* Count references from TTY module */
 623         return err;
 624 }
 625
 626 /*
 627  * Close down a SLCAN channel.
 628  * This means flushing out any pending queues, and then returning. This
 629  * call is serialized against other ldisc functions.
 630  *
 631  * We also use this method for a hangup event.
 632  */
 633
 634 static void slcan_close(struct tty_struct *tty)
 635 {
 636         struct slcan *sl = (struct slcan *) tty->disc_data;
 637
 638         /* First make sure we're connected. */
 639         if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
 640                 return;
 641
 642         spin_lock_bh(&sl->lock);
 643         tty->disc_data = NULL;
 644         sl->tty = NULL;
 645         spin_unlock_bh(&sl->lock);
 646
 647         flush_work(&sl->tx_work);
 648
 649         /* Flush network side */
 650         unregister_netdev(sl->dev);
 651         /* This will complete via sl_free_netdev */
 652 }
 653
 654 static int slcan_hangup(struct tty_struct *tty)
 655 {
 656         slcan_close(tty);
 657         return 0;
 658 }
 659
 660 /* Perform I/O control on an active SLCAN channel. */
 661 static int slcan_ioctl(struct tty_struct *tty, struct file *file,
 662                        unsigned int cmd, unsigned long arg)
 663 {
 664         struct slcan *sl = (struct slcan *) tty->disc_data;
 665         unsigned int tmp;
 666
 667         /* First make sure we're connected. */
 668         if (!sl || sl->magic != SLCAN_MAGIC)
 669                 return -EINVAL;
 670
 671         switch (cmd) {
 672         case SIOCGIFNAME:
 673                 tmp = strlen(sl->dev->name) + 1;
 674                 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
 675                         return -EFAULT;
 676                 return 0;
 677
 678         case SIOCSIFHWADDR:
 679                 return -EINVAL;
 680
 681         default:
 682                 return tty_mode_ioctl(tty, file, cmd, arg);
 683         }
 684 }
 685
 686 static struct tty_ldisc_ops slc_ldisc = {
 687         .owner          = THIS_MODULE,
 688         .magic          = TTY_LDISC_MAGIC,
 689         .name           = "slcan",
 690         .open           = slcan_open,
 691         .close          = slcan_close,
 692         .hangup         = slcan_hangup,
 693         .ioctl          = slcan_ioctl,
 694         .receive_buf    = slcan_receive_buf,
 695         .write_wakeup   = slcan_write_wakeup,
 696 };
 697
 698 static int __init slcan_init(void)
 699 {
 700         int status;
 701
 702         if (maxdev < 4)
 703                 maxdev = 4; /* Sanity */
 704
 705         printk(banner);
 706         printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
 707
 708         slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
 709         if (!slcan_devs)
 710                 return -ENOMEM;
 711
 712         /* Fill in our line protocol discipline, and register it */
 713         status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
 714         if (status)  {
 715                 printk(KERN_ERR "slcan: can't register line discipline\n");
 716                 kfree(slcan_devs);
 717         }
 718         return status;
 719 }
 720
 721 static void __exit slcan_exit(void)
 722 {
 723         int i;
 724         struct net_device *dev;
 725         struct slcan *sl;
 726         unsigned long timeout = jiffies + HZ;
 727         int busy = 0;
 728
 729         if (slcan_devs == NULL)
 730                 return;
 731
 732         /* First of all: check for active disciplines and hangup them.
 733          */
 734         do {
 735                 if (busy)
 736                         msleep_interruptible(100);
 737
 738                 busy = 0;
 739                 for (i = 0; i < maxdev; i++) {
 740                         dev = slcan_devs[i];
 741                         if (!dev)
 742                                 continue;
 743                         sl = netdev_priv(dev);
 744                         spin_lock_bh(&sl->lock);
 745                         if (sl->tty) {
 746                                 busy++;
 747                                 tty_hangup(sl->tty);
 748                         }
 749                         spin_unlock_bh(&sl->lock);
 750                 }
 751         } while (busy && time_before(jiffies, timeout));
 752
 753         /* FIXME: hangup is async so we should wait when doing this second
 754            phase */
 755
 756         for (i = 0; i < maxdev; i++) {
 757                 dev = slcan_devs[i];
 758                 if (!dev)
 759                         continue;
 760                 slcan_devs[i] = NULL;
 761
 762                 sl = netdev_priv(dev);
 763                 if (sl->tty) {
 764                         printk(KERN_ERR "%s: tty discipline still running\n",
 765                                dev->name);
 766                         /* Intentionally leak the control block. */
 767                         dev->destructor = NULL;
 768                 }
 769
 770                 unregister_netdev(dev);
 771         }
 772
 773         kfree(slcan_devs);
 774         slcan_devs = NULL;
 775
 776         i = tty_unregister_ldisc(N_SLCAN);
 777         if (i)
 778                 printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
 779 }
 780
 781 module_init(slcan_init);
 782 module_exit(slcan_exit);