drivers/net/wan/x25_asy.c

   1 /*
   2  *      Things to sort out:
   3  *
   4  *      o       tbusy handling
   5  *      o       allow users to set the parameters
   6  *      o       sync/async switching ?
   7  *
   8  *      Note: This does _not_ implement CCITT X.25 asynchronous framing
   9  *      recommendations. Its primarily for testing purposes. If you wanted
  10  *      to do CCITT then in theory all you need is to nick the HDLC async
  11  *      checksum routines from ppp.c
  12  *      Changes:
  13  *
  14  *      2000-10-29      Henner Eisen    lapb_data_indication() return status.
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/module.h>
  20
  21 #include <linux/uaccess.h>
  22 #include <linux/bitops.h>
  23 #include <linux/string.h>
  24 #include <linux/mm.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/in.h>
  27 #include <linux/tty.h>
  28 #include <linux/errno.h>
  29 #include <linux/netdevice.h>
  30 #include <linux/etherdevice.h>
  31 #include <linux/skbuff.h>
  32 #include <linux/if_arp.h>
  33 #include <linux/lapb.h>
  34 #include <linux/init.h>
  35 #include <linux/rtnetlink.h>
  36 #include <linux/slab.h>
  37 #include <net/x25device.h>
  38 #include "x25_asy.h"
  39
  40 static struct net_device **x25_asy_devs;
  41 static int x25_asy_maxdev = SL_NRUNIT;
  42
  43 module_param(x25_asy_maxdev, int, 0);
  44 MODULE_LICENSE("GPL");
  45
  46 static int x25_asy_esc(unsigned char *p, unsigned char *d, int len);
  47 static void x25_asy_unesc(struct x25_asy *sl, unsigned char c);
  48 static void x25_asy_setup(struct net_device *dev);
  49
  50 /* Find a free X.25 channel, and link in this `tty' line. */
  51 static struct x25_asy *x25_asy_alloc(void)
  52 {
  53         struct net_device *dev = NULL;
  54         struct x25_asy *sl;
  55         int i;
  56
  57         if (x25_asy_devs == NULL)
  58                 return NULL;    /* Master array missing ! */
  59
  60         for (i = 0; i < x25_asy_maxdev; i++) {
  61                 dev = x25_asy_devs[i];
  62
  63                 /* Not allocated ? */
  64                 if (dev == NULL)
  65                         break;
  66
  67                 sl = netdev_priv(dev);
  68                 /* Not in use ? */
  69                 if (!test_and_set_bit(SLF_INUSE, &sl->flags))
  70                         return sl;
  71         }
  72
  73
  74         /* Sorry, too many, all slots in use */
  75         if (i >= x25_asy_maxdev)
  76                 return NULL;
  77
  78         /* If no channels are available, allocate one */
  79         if (!dev) {
  80                 char name[IFNAMSIZ];
  81                 sprintf(name, "x25asy%d", i);
  82
  83                 dev = alloc_netdev(sizeof(struct x25_asy), name,
  84                                    NET_NAME_UNKNOWN, x25_asy_setup);
  85                 if (!dev)
  86                         return NULL;
  87
  88                 /* Initialize channel control data */
  89                 sl = netdev_priv(dev);
  90                 dev->base_addr    = i;
  91
  92                 /* register device so that it can be ifconfig'ed       */
  93                 if (register_netdev(dev) == 0) {
  94                         /* (Re-)Set the INUSE bit.   Very Important! */
  95                         set_bit(SLF_INUSE, &sl->flags);
  96                         x25_asy_devs[i] = dev;
  97                         return sl;
  98                 } else {
  99                         pr_warn("%s(): register_netdev() failure\n", __func__);
 100                         free_netdev(dev);
 101                 }
 102         }
 103         return NULL;
 104 }
 105
 106
 107 /* Free an X.25 channel. */
 108 static void x25_asy_free(struct x25_asy *sl)
 109 {
 110         /* Free all X.25 frame buffers. */
 111         kfree(sl->rbuff);
 112         sl->rbuff = NULL;
 113         kfree(sl->xbuff);
 114         sl->xbuff = NULL;
 115
 116         if (!test_and_clear_bit(SLF_INUSE, &sl->flags))
 117                 netdev_err(sl->dev, "x25_asy_free for already free unit\n");
 118 }
 119
 120 static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
 121 {
 122         struct x25_asy *sl = netdev_priv(dev);
 123         unsigned char *xbuff, *rbuff;
 124         int len;
 125
 126         len = 2 * newmtu;
 127         xbuff = kmalloc(len + 4, GFP_ATOMIC);
 128         rbuff = kmalloc(len + 4, GFP_ATOMIC);
 129
 130         if (xbuff == NULL || rbuff == NULL) {
 131                 kfree(xbuff);
 132                 kfree(rbuff);
 133                 return -ENOMEM;
 134         }
 135
 136         spin_lock_bh(&sl->lock);
 137         xbuff    = xchg(&sl->xbuff, xbuff);
 138         if (sl->xleft)  {
 139                 if (sl->xleft <= len)  {
 140                         memcpy(sl->xbuff, sl->xhead, sl->xleft);
 141                 } else  {
 142                         sl->xleft = 0;
 143                         dev->stats.tx_dropped++;
 144                 }
 145         }
 146         sl->xhead = sl->xbuff;
 147
 148         rbuff    = xchg(&sl->rbuff, rbuff);
 149         if (sl->rcount)  {
 150                 if (sl->rcount <= len) {
 151                         memcpy(sl->rbuff, rbuff, sl->rcount);
 152                 } else  {
 153                         sl->rcount = 0;
 154                         dev->stats.rx_over_errors++;
 155                         set_bit(SLF_ERROR, &sl->flags);
 156                 }
 157         }
 158
 159         dev->mtu    = newmtu;
 160         sl->buffsize = len;
 161
 162         spin_unlock_bh(&sl->lock);
 163
 164         kfree(xbuff);
 165         kfree(rbuff);
 166         return 0;
 167 }
 168
 169
 170 /* Set the "sending" flag.  This must be atomic, hence the ASM. */
 171
 172 static inline void x25_asy_lock(struct x25_asy *sl)
 173 {
 174         netif_stop_queue(sl->dev);
 175 }
 176
 177
 178 /* Clear the "sending" flag.  This must be atomic, hence the ASM. */
 179
 180 static inline void x25_asy_unlock(struct x25_asy *sl)
 181 {
 182         netif_wake_queue(sl->dev);
 183 }
 184
 185 /* Send one completely decapsulated IP datagram to the IP layer. */
 186
 187 static void x25_asy_bump(struct x25_asy *sl)
 188 {
 189         struct net_device *dev = sl->dev;
 190         struct sk_buff *skb;
 191         int count;
 192         int err;
 193
 194         count = sl->rcount;
 195         dev->stats.rx_bytes += count;
 196
 197         skb = dev_alloc_skb(count+1);
 198         if (skb == NULL) {
 199                 netdev_warn(sl->dev, "memory squeeze, dropping packet\n");
 200                 dev->stats.rx_dropped++;
 201                 return;
 202         }
 203         skb_push(skb, 1);       /* LAPB internal control */
 204         skb_put_data(skb, sl->rbuff, count);
 205         skb->protocol = x25_type_trans(skb, sl->dev);
 206         err = lapb_data_received(skb->dev, skb);
 207         if (err != LAPB_OK) {
 208                 kfree_skb(skb);
 209                 printk(KERN_DEBUG "x25_asy: data received err - %d\n", err);
 210         } else {
 211                 netif_rx(skb);
 212                 dev->stats.rx_packets++;
 213         }
 214 }
 215
 216 /* Encapsulate one IP datagram and stuff into a TTY queue. */
 217 static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
 218 {
 219         unsigned char *p;
 220         int actual, count, mtu = sl->dev->mtu;
 221
 222         if (len > mtu) {
 223                 /* Sigh, shouldn't occur BUT ... */
 224                 len = mtu;
 225                 printk(KERN_DEBUG "%s: truncating oversized transmit packet!\n",
 226                                         sl->dev->name);
 227                 sl->dev->stats.tx_dropped++;
 228                 x25_asy_unlock(sl);
 229                 return;
 230         }
 231
 232         p = icp;
 233         count = x25_asy_esc(p, sl->xbuff, len);
 234
 235         /* Order of next two lines is *very* important.
 236          * When we are sending a little amount of data,
 237          * the transfer may be completed inside driver.write()
 238          * routine, because it's running with interrupts enabled.
 239          * In this case we *never* got WRITE_WAKEUP event,
 240          * if we did not request it before write operation.
 241          *       14 Oct 1994  Dmitry Gorodchanin.
 242          */
 243         set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 244         actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
 245         sl->xleft = count - actual;
 246         sl->xhead = sl->xbuff + actual;
 247         /* VSV */
 248         clear_bit(SLF_OUTWAIT, &sl->flags);     /* reset outfill flag */
 249 }
 250
 251 /*
 252  * Called by the driver when there's room for more data.  If we have
 253  * more packets to send, we send them here.
 254  */
 255 static void x25_asy_write_wakeup(struct tty_struct *tty)
 256 {
 257         int actual;
 258         struct x25_asy *sl = tty->disc_data;
 259
 260         /* First make sure we're connected. */
 261         if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
 262                 return;
 263
 264         if (sl->xleft <= 0) {
 265                 /* Now serial buffer is almost free & we can start
 266                  * transmission of another packet */
 267                 sl->dev->stats.tx_packets++;
 268                 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 269                 x25_asy_unlock(sl);
 270                 return;
 271         }
 272
 273         actual = tty->ops->write(tty, sl->xhead, sl->xleft);
 274         sl->xleft -= actual;
 275         sl->xhead += actual;
 276 }
 277
 278 static void x25_asy_timeout(struct net_device *dev)
 279 {
 280         struct x25_asy *sl = netdev_priv(dev);
 281
 282         spin_lock(&sl->lock);
 283         if (netif_queue_stopped(dev)) {
 284                 /* May be we must check transmitter timeout here ?
 285                  *      14 Oct 1994 Dmitry Gorodchanin.
 286                  */
 287                 netdev_warn(dev, "transmit timed out, %s?\n",
 288                             (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
 289                             "bad line quality" : "driver error");
 290                 sl->xleft = 0;
 291                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 292                 x25_asy_unlock(sl);
 293         }
 294         spin_unlock(&sl->lock);
 295 }
 296
 297 /* Encapsulate an IP datagram and kick it into a TTY queue. */
 298
 299 static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
 300                                       struct net_device *dev)
 301 {
 302         struct x25_asy *sl = netdev_priv(dev);
 303         int err;
 304
 305         if (!netif_running(sl->dev)) {
 306                 netdev_err(dev, "xmit call when iface is down\n");
 307                 kfree_skb(skb);
 308                 return NETDEV_TX_OK;
 309         }
 310
 311         switch (skb->data[0]) {
 312         case X25_IFACE_DATA:
 313                 break;
 314         case X25_IFACE_CONNECT: /* Connection request .. do nothing */
 315                 err = lapb_connect_request(dev);
 316                 if (err != LAPB_OK)
 317                         netdev_err(dev, "lapb_connect_request error: %d\n",
 318                                    err);
 319                 kfree_skb(skb);
 320                 return NETDEV_TX_OK;
 321         case X25_IFACE_DISCONNECT: /* do nothing - hang up ?? */
 322                 err = lapb_disconnect_request(dev);
 323                 if (err != LAPB_OK)
 324                         netdev_err(dev, "lapb_disconnect_request error: %d\n",
 325                                    err);
 326                 /* fall through */
 327         default:
 328                 kfree_skb(skb);
 329                 return NETDEV_TX_OK;
 330         }
 331         skb_pull(skb, 1);       /* Remove control byte */
 332         /*
 333          * If we are busy already- too bad.  We ought to be able
 334          * to queue things at this point, to allow for a little
 335          * frame buffer.  Oh well...
 336          * -----------------------------------------------------
 337          * I hate queues in X.25 driver. May be it's efficient,
 338          * but for me latency is more important. ;)
 339          * So, no queues !
 340          *        14 Oct 1994  Dmitry Gorodchanin.
 341          */
 342
 343         err = lapb_data_request(dev, skb);
 344         if (err != LAPB_OK) {
 345                 netdev_err(dev, "lapb_data_request error: %d\n", err);
 346                 kfree_skb(skb);
 347                 return NETDEV_TX_OK;
 348         }
 349         return NETDEV_TX_OK;
 350 }
 351
 352
 353 /*
 354  *      LAPB interface boilerplate
 355  */
 356
 357 /*
 358  *      Called when I frame data arrives. We did the work above - throw it
 359  *      at the net layer.
 360  */
 361
 362 static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
 363 {
 364         return netif_rx(skb);
 365 }
 366
 367 /*
 368  *      Data has emerged from the LAPB protocol machine. We don't handle
 369  *      busy cases too well. Its tricky to see how to do this nicely -
 370  *      perhaps lapb should allow us to bounce this ?
 371  */
 372
 373 static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
 374 {
 375         struct x25_asy *sl = netdev_priv(dev);
 376
 377         spin_lock(&sl->lock);
 378         if (netif_queue_stopped(sl->dev) || sl->tty == NULL) {
 379                 spin_unlock(&sl->lock);
 380                 netdev_err(dev, "tbusy drop\n");
 381                 kfree_skb(skb);
 382                 return;
 383         }
 384         /* We were not busy, so we are now... :-) */
 385         if (skb != NULL) {
 386                 x25_asy_lock(sl);
 387                 dev->stats.tx_bytes += skb->len;
 388                 x25_asy_encaps(sl, skb->data, skb->len);
 389                 dev_kfree_skb(skb);
 390         }
 391         spin_unlock(&sl->lock);
 392 }
 393
 394 /*
 395  *      LAPB connection establish/down information.
 396  */
 397
 398 static void x25_asy_connected(struct net_device *dev, int reason)
 399 {
 400         struct x25_asy *sl = netdev_priv(dev);
 401         struct sk_buff *skb;
 402         unsigned char *ptr;
 403
 404         skb = dev_alloc_skb(1);
 405         if (skb == NULL) {
 406                 netdev_err(dev, "out of memory\n");
 407                 return;
 408         }
 409
 410         ptr  = skb_put(skb, 1);
 411         *ptr = X25_IFACE_CONNECT;
 412
 413         skb->protocol = x25_type_trans(skb, sl->dev);
 414         netif_rx(skb);
 415 }
 416
 417 static void x25_asy_disconnected(struct net_device *dev, int reason)
 418 {
 419         struct x25_asy *sl = netdev_priv(dev);
 420         struct sk_buff *skb;
 421         unsigned char *ptr;
 422
 423         skb = dev_alloc_skb(1);
 424         if (skb == NULL) {
 425                 netdev_err(dev, "out of memory\n");
 426                 return;
 427         }
 428
 429         ptr  = skb_put(skb, 1);
 430         *ptr = X25_IFACE_DISCONNECT;
 431
 432         skb->protocol = x25_type_trans(skb, sl->dev);
 433         netif_rx(skb);
 434 }
 435
 436 static const struct lapb_register_struct x25_asy_callbacks = {
 437         .connect_confirmation = x25_asy_connected,
 438         .connect_indication = x25_asy_connected,
 439         .disconnect_confirmation = x25_asy_disconnected,
 440         .disconnect_indication = x25_asy_disconnected,
 441         .data_indication = x25_asy_data_indication,
 442         .data_transmit = x25_asy_data_transmit,
 443 };
 444
 445
 446 /* Open the low-level part of the X.25 channel. Easy! */
 447 static int x25_asy_open(struct net_device *dev)
 448 {
 449         struct x25_asy *sl = netdev_priv(dev);
 450         unsigned long len;
 451         int err;
 452
 453         if (sl->tty == NULL)
 454                 return -ENODEV;
 455
 456         /*
 457          * Allocate the X.25 frame buffers:
 458          *
 459          * rbuff        Receive buffer.
 460          * xbuff        Transmit buffer.
 461          */
 462
 463         len = dev->mtu * 2;
 464
 465         sl->rbuff = kmalloc(len + 4, GFP_KERNEL);
 466         if (sl->rbuff == NULL)
 467                 goto norbuff;
 468         sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
 469         if (sl->xbuff == NULL)
 470                 goto noxbuff;
 471
 472         sl->buffsize = len;
 473         sl->rcount   = 0;
 474         sl->xleft    = 0;
 475         sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
 476
 477         netif_start_queue(dev);
 478
 479         /*
 480          *      Now attach LAPB
 481          */
 482         err = lapb_register(dev, &x25_asy_callbacks);
 483         if (err == LAPB_OK)
 484                 return 0;
 485
 486         /* Cleanup */
 487         kfree(sl->xbuff);
 488 noxbuff:
 489         kfree(sl->rbuff);
 490 norbuff:
 491         return -ENOMEM;
 492 }
 493
 494
 495 /* Close the low-level part of the X.25 channel. Easy! */
 496 static int x25_asy_close(struct net_device *dev)
 497 {
 498         struct x25_asy *sl = netdev_priv(dev);
 499
 500         spin_lock(&sl->lock);
 501         if (sl->tty)
 502                 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 503
 504         netif_stop_queue(dev);
 505         sl->rcount = 0;
 506         sl->xleft  = 0;
 507         spin_unlock(&sl->lock);
 508         return 0;
 509 }
 510
 511 /*
 512  * Handle the 'receiver data ready' interrupt.
 513  * This function is called by the 'tty_io' module in the kernel when
 514  * a block of X.25 data has been received, which can now be decapsulated
 515  * and sent on to some IP layer for further processing.
 516  */
 517
 518 static void x25_asy_receive_buf(struct tty_struct *tty,
 519                                 const unsigned char *cp, char *fp, int count)
 520 {
 521         struct x25_asy *sl = tty->disc_data;
 522
 523         if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
 524                 return;
 525
 526
 527         /* Read the characters out of the buffer */
 528         while (count--) {
 529                 if (fp && *fp++) {
 530                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
 531                                 sl->dev->stats.rx_errors++;
 532                         cp++;
 533                         continue;
 534                 }
 535                 x25_asy_unesc(sl, *cp++);
 536         }
 537 }
 538
 539 /*
 540  * Open the high-level part of the X.25 channel.
 541  * This function is called by the TTY module when the
 542  * X.25 line discipline is called for.  Because we are
 543  * sure the tty line exists, we only have to link it to
 544  * a free X.25 channel...
 545  */
 546
 547 static int x25_asy_open_tty(struct tty_struct *tty)
 548 {
 549         struct x25_asy *sl;
 550         int err;
 551
 552         if (tty->ops->write == NULL)
 553                 return -EOPNOTSUPP;
 554
 555         /* OK.  Find a free X.25 channel to use. */
 556         sl = x25_asy_alloc();
 557         if (sl == NULL)
 558                 return -ENFILE;
 559
 560         sl->tty = tty;
 561         tty->disc_data = sl;
 562         tty->receive_room = 65536;
 563         tty_driver_flush_buffer(tty);
 564         tty_ldisc_flush(tty);
 565
 566         /* Restore default settings */
 567         sl->dev->type = ARPHRD_X25;
 568
 569         /* Perform the low-level X.25 async init */
 570         err = x25_asy_open(sl->dev);
 571         if (err) {
 572                 x25_asy_free(sl);
 573                 return err;
 574         }
 575         /* Done.  We have linked the TTY line to a channel. */
 576         return 0;
 577 }
 578
 579
 580 /*
 581  * Close down an X.25 channel.
 582  * This means flushing out any pending queues, and then restoring the
 583  * TTY line discipline to what it was before it got hooked to X.25
 584  * (which usually is TTY again).
 585  */
 586 static void x25_asy_close_tty(struct tty_struct *tty)
 587 {
 588         struct x25_asy *sl = tty->disc_data;
 589         int err;
 590
 591         /* First make sure we're connected. */
 592         if (!sl || sl->magic != X25_ASY_MAGIC)
 593                 return;
 594
 595         rtnl_lock();
 596         if (sl->dev->flags & IFF_UP)
 597                 dev_close(sl->dev);
 598         rtnl_unlock();
 599
 600         err = lapb_unregister(sl->dev);
 601         if (err != LAPB_OK)
 602                 pr_err("x25_asy_close: lapb_unregister error: %d\n",
 603                        err);
 604
 605         tty->disc_data = NULL;
 606         sl->tty = NULL;
 607         x25_asy_free(sl);
 608 }
 609
 610  /************************************************************************
 611   *                     STANDARD X.25 ENCAPSULATION                      *
 612   ************************************************************************/
 613
 614 static int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
 615 {
 616         unsigned char *ptr = d;
 617         unsigned char c;
 618
 619         /*
 620          * Send an initial END character to flush out any
 621          * data that may have accumulated in the receiver
 622          * due to line noise.
 623          */
 624
 625         *ptr++ = X25_END;       /* Send 10111110 bit seq */
 626
 627         /*
 628          * For each byte in the packet, send the appropriate
 629          * character sequence, according to the X.25 protocol.
 630          */
 631
 632         while (len-- > 0) {
 633                 switch (c = *s++) {
 634                 case X25_END:
 635                         *ptr++ = X25_ESC;
 636                         *ptr++ = X25_ESCAPE(X25_END);
 637                         break;
 638                 case X25_ESC:
 639                         *ptr++ = X25_ESC;
 640                         *ptr++ = X25_ESCAPE(X25_ESC);
 641                         break;
 642                 default:
 643                         *ptr++ = c;
 644                         break;
 645                 }
 646         }
 647         *ptr++ = X25_END;
 648         return ptr - d;
 649 }
 650
 651 static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
 652 {
 653
 654         switch (s) {
 655         case X25_END:
 656                 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
 657                     sl->rcount > 2)
 658                         x25_asy_bump(sl);
 659                 clear_bit(SLF_ESCAPE, &sl->flags);
 660                 sl->rcount = 0;
 661                 return;
 662         case X25_ESC:
 663                 set_bit(SLF_ESCAPE, &sl->flags);
 664                 return;
 665         case X25_ESCAPE(X25_ESC):
 666         case X25_ESCAPE(X25_END):
 667                 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
 668                         s = X25_UNESCAPE(s);
 669                 break;
 670         }
 671         if (!test_bit(SLF_ERROR, &sl->flags)) {
 672                 if (sl->rcount < sl->buffsize) {
 673                         sl->rbuff[sl->rcount++] = s;
 674                         return;
 675                 }
 676                 sl->dev->stats.rx_over_errors++;
 677                 set_bit(SLF_ERROR, &sl->flags);
 678         }
 679 }
 680
 681
 682 /* Perform I/O control on an active X.25 channel. */
 683 static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
 684                          unsigned int cmd,  unsigned long arg)
 685 {
 686         struct x25_asy *sl = tty->disc_data;
 687
 688         /* First make sure we're connected. */
 689         if (!sl || sl->magic != X25_ASY_MAGIC)
 690                 return -EINVAL;
 691
 692         switch (cmd) {
 693         case SIOCGIFNAME:
 694                 if (copy_to_user((void __user *)arg, sl->dev->name,
 695                                         strlen(sl->dev->name) + 1))
 696                         return -EFAULT;
 697                 return 0;
 698         case SIOCSIFHWADDR:
 699                 return -EINVAL;
 700         default:
 701                 return tty_mode_ioctl(tty, file, cmd, arg);
 702         }
 703 }
 704
 705 static int x25_asy_open_dev(struct net_device *dev)
 706 {
 707         struct x25_asy *sl = netdev_priv(dev);
 708         if (sl->tty == NULL)
 709                 return -ENODEV;
 710         return 0;
 711 }
 712
 713 static const struct net_device_ops x25_asy_netdev_ops = {
 714         .ndo_open       = x25_asy_open_dev,
 715         .ndo_stop       = x25_asy_close,
 716         .ndo_start_xmit = x25_asy_xmit,
 717         .ndo_tx_timeout = x25_asy_timeout,
 718         .ndo_change_mtu = x25_asy_change_mtu,
 719 };
 720
 721 /* Initialise the X.25 driver.  Called by the device init code */
 722 static void x25_asy_setup(struct net_device *dev)
 723 {
 724         struct x25_asy *sl = netdev_priv(dev);
 725
 726         sl->magic  = X25_ASY_MAGIC;
 727         sl->dev    = dev;
 728         spin_lock_init(&sl->lock);
 729         set_bit(SLF_INUSE, &sl->flags);
 730
 731         /*
 732          *      Finish setting up the DEVICE info.
 733          */
 734
 735         dev->mtu                = SL_MTU;
 736         dev->min_mtu            = 0;
 737         dev->max_mtu            = 65534;
 738         dev->netdev_ops         = &x25_asy_netdev_ops;
 739         dev->watchdog_timeo     = HZ*20;
 740         dev->hard_header_len    = 0;
 741         dev->addr_len           = 0;
 742         dev->type               = ARPHRD_X25;
 743         dev->tx_queue_len       = 10;
 744
 745         /* New-style flags. */
 746         dev->flags              = IFF_NOARP;
 747 }
 748
 749 static struct tty_ldisc_ops x25_ldisc = {
 750         .owner          = THIS_MODULE,
 751         .magic          = TTY_LDISC_MAGIC,
 752         .name           = "X.25",
 753         .open           = x25_asy_open_tty,
 754         .close          = x25_asy_close_tty,
 755         .ioctl          = x25_asy_ioctl,
 756         .receive_buf    = x25_asy_receive_buf,
 757         .write_wakeup   = x25_asy_write_wakeup,
 758 };
 759
 760 static int __init init_x25_asy(void)
 761 {
 762         if (x25_asy_maxdev < 4)
 763                 x25_asy_maxdev = 4; /* Sanity */
 764
 765         pr_info("X.25 async: version 0.00 ALPHA (dynamic channels, max=%d)\n",
 766                 x25_asy_maxdev);
 767
 768         x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device *),
 769                                 GFP_KERNEL);
 770         if (!x25_asy_devs)
 771                 return -ENOMEM;
 772
 773         return tty_register_ldisc(N_X25, &x25_ldisc);
 774 }
 775
 776
 777 static void __exit exit_x25_asy(void)
 778 {
 779         struct net_device *dev;
 780         int i;
 781
 782         for (i = 0; i < x25_asy_maxdev; i++) {
 783                 dev = x25_asy_devs[i];
 784                 if (dev) {
 785                         struct x25_asy *sl = netdev_priv(dev);
 786
 787                         spin_lock_bh(&sl->lock);
 788                         if (sl->tty)
 789                                 tty_hangup(sl->tty);
 790
 791                         spin_unlock_bh(&sl->lock);
 792                         /*
 793                          * VSV = if dev->start==0, then device
 794                          * unregistered while close proc.
 795                          */
 796                         unregister_netdev(dev);
 797                         free_netdev(dev);
 798                 }
 799         }
 800
 801         kfree(x25_asy_devs);
 802         tty_unregister_ldisc(N_X25);
 803 }
 804
 805 module_init(init_x25_asy);
 806 module_exit(exit_x25_asy);