linux/drivers/net/hamradio/6pack.c
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   1/*
   2 * 6pack.c      This module implements the 6pack protocol for kernel-based
   3 *              devices like TTY. It interfaces between a raw TTY and the
   4 *              kernel's AX.25 protocol layers.
   5 *
   6 * Authors:     Andreas Könsgen <ajk@comnets.uni-bremen.de>
   7 *              Ralf Baechle DL5RB <ralf@linux-mips.org>
   8 *
   9 * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
  10 *
  11 *              Laurence Culhane, <loz@holmes.demon.co.uk>
  12 *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  13 */
  14
  15#include <linux/module.h>
  16#include <linux/uaccess.h>
  17#include <linux/bitops.h>
  18#include <linux/string.h>
  19#include <linux/mm.h>
  20#include <linux/interrupt.h>
  21#include <linux/in.h>
  22#include <linux/tty.h>
  23#include <linux/errno.h>
  24#include <linux/netdevice.h>
  25#include <linux/timer.h>
  26#include <linux/slab.h>
  27#include <net/ax25.h>
  28#include <linux/etherdevice.h>
  29#include <linux/skbuff.h>
  30#include <linux/rtnetlink.h>
  31#include <linux/spinlock.h>
  32#include <linux/if_arp.h>
  33#include <linux/init.h>
  34#include <linux/ip.h>
  35#include <linux/tcp.h>
  36#include <linux/semaphore.h>
  37#include <linux/compat.h>
  38#include <linux/atomic.h>
  39
  40#define SIXPACK_VERSION    "Revision: 0.3.0"
  41
  42/* sixpack priority commands */
  43#define SIXP_SEOF               0x40    /* start and end of a 6pack frame */
  44#define SIXP_TX_URUN            0x48    /* transmit overrun */
  45#define SIXP_RX_ORUN            0x50    /* receive overrun */
  46#define SIXP_RX_BUF_OVL         0x58    /* receive buffer overflow */
  47
  48#define SIXP_CHKSUM             0xFF    /* valid checksum of a 6pack frame */
  49
  50/* masks to get certain bits out of the status bytes sent by the TNC */
  51
  52#define SIXP_CMD_MASK           0xC0
  53#define SIXP_CHN_MASK           0x07
  54#define SIXP_PRIO_CMD_MASK      0x80
  55#define SIXP_STD_CMD_MASK       0x40
  56#define SIXP_PRIO_DATA_MASK     0x38
  57#define SIXP_TX_MASK            0x20
  58#define SIXP_RX_MASK            0x10
  59#define SIXP_RX_DCD_MASK        0x18
  60#define SIXP_LEDS_ON            0x78
  61#define SIXP_LEDS_OFF           0x60
  62#define SIXP_CON                0x08
  63#define SIXP_STA                0x10
  64
  65#define SIXP_FOUND_TNC          0xe9
  66#define SIXP_CON_ON             0x68
  67#define SIXP_DCD_MASK           0x08
  68#define SIXP_DAMA_OFF           0
  69
  70/* default level 2 parameters */
  71#define SIXP_TXDELAY                    (HZ/4)  /* in 1 s */
  72#define SIXP_PERSIST                    50      /* in 256ths */
  73#define SIXP_SLOTTIME                   (HZ/10) /* in 1 s */
  74#define SIXP_INIT_RESYNC_TIMEOUT        (3*HZ/2) /* in 1 s */
  75#define SIXP_RESYNC_TIMEOUT             5*HZ    /* in 1 s */
  76
  77/* 6pack configuration. */
  78#define SIXP_NRUNIT                     31      /* MAX number of 6pack channels */
  79#define SIXP_MTU                        256     /* Default MTU */
  80
  81enum sixpack_flags {
  82        SIXPF_ERROR,    /* Parity, etc. error   */
  83};
  84
  85struct sixpack {
  86        /* Various fields. */
  87        struct tty_struct       *tty;           /* ptr to TTY structure */
  88        struct net_device       *dev;           /* easy for intr handling  */
  89
  90        /* These are pointers to the malloc()ed frame buffers. */
  91        unsigned char           *rbuff;         /* receiver buffer      */
  92        int                     rcount;         /* received chars counter  */
  93        unsigned char           *xbuff;         /* transmitter buffer   */
  94        unsigned char           *xhead;         /* next byte to XMIT */
  95        int                     xleft;          /* bytes left in XMIT queue  */
  96
  97        unsigned char           raw_buf[4];
  98        unsigned char           cooked_buf[400];
  99
 100        unsigned int            rx_count;
 101        unsigned int            rx_count_cooked;
 102
 103        int                     mtu;            /* Our mtu (to spot changes!) */
 104        int                     buffsize;       /* Max buffers sizes */
 105
 106        unsigned long           flags;          /* Flag values/ mode etc */
 107        unsigned char           mode;           /* 6pack mode */
 108
 109        /* 6pack stuff */
 110        unsigned char           tx_delay;
 111        unsigned char           persistence;
 112        unsigned char           slottime;
 113        unsigned char           duplex;
 114        unsigned char           led_state;
 115        unsigned char           status;
 116        unsigned char           status1;
 117        unsigned char           status2;
 118        unsigned char           tx_enable;
 119        unsigned char           tnc_state;
 120
 121        struct timer_list       tx_t;
 122        struct timer_list       resync_t;
 123        atomic_t                refcnt;
 124        struct semaphore        dead_sem;
 125        spinlock_t              lock;
 126};
 127
 128#define AX25_6PACK_HEADER_LEN 0
 129
 130static void sixpack_decode(struct sixpack *, const unsigned char[], int);
 131static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
 132
 133/*
 134 * Perform the persistence/slottime algorithm for CSMA access. If the
 135 * persistence check was successful, write the data to the serial driver.
 136 * Note that in case of DAMA operation, the data is not sent here.
 137 */
 138
 139static void sp_xmit_on_air(unsigned long channel)
 140{
 141        struct sixpack *sp = (struct sixpack *) channel;
 142        int actual, when = sp->slottime;
 143        static unsigned char random;
 144
 145        random = random * 17 + 41;
 146
 147        if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
 148                sp->led_state = 0x70;
 149                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 150                sp->tx_enable = 1;
 151                actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
 152                sp->xleft -= actual;
 153                sp->xhead += actual;
 154                sp->led_state = 0x60;
 155                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 156                sp->status2 = 0;
 157        } else
 158                mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
 159}
 160
 161/* ----> 6pack timer interrupt handler and friends. <---- */
 162
 163/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
 164static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
 165{
 166        unsigned char *msg, *p = icp;
 167        int actual, count;
 168
 169        if (len > sp->mtu) {    /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
 170                msg = "oversized transmit packet!";
 171                goto out_drop;
 172        }
 173
 174        if (len > sp->mtu) {    /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
 175                msg = "oversized transmit packet!";
 176                goto out_drop;
 177        }
 178
 179        if (p[0] > 5) {
 180                msg = "invalid KISS command";
 181                goto out_drop;
 182        }
 183
 184        if ((p[0] != 0) && (len > 2)) {
 185                msg = "KISS control packet too long";
 186                goto out_drop;
 187        }
 188
 189        if ((p[0] == 0) && (len < 15)) {
 190                msg = "bad AX.25 packet to transmit";
 191                goto out_drop;
 192        }
 193
 194        count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
 195        set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
 196
 197        switch (p[0]) {
 198        case 1: sp->tx_delay = p[1];
 199                return;
 200        case 2: sp->persistence = p[1];
 201                return;
 202        case 3: sp->slottime = p[1];
 203                return;
 204        case 4: /* ignored */
 205                return;
 206        case 5: sp->duplex = p[1];
 207                return;
 208        }
 209
 210        if (p[0] != 0)
 211                return;
 212
 213        /*
 214         * In case of fullduplex or DAMA operation, we don't take care about the
 215         * state of the DCD or of any timers, as the determination of the
 216         * correct time to send is the job of the AX.25 layer. We send
 217         * immediately after data has arrived.
 218         */
 219        if (sp->duplex == 1) {
 220                sp->led_state = 0x70;
 221                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 222                sp->tx_enable = 1;
 223                actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
 224                sp->xleft = count - actual;
 225                sp->xhead = sp->xbuff + actual;
 226                sp->led_state = 0x60;
 227                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 228        } else {
 229                sp->xleft = count;
 230                sp->xhead = sp->xbuff;
 231                sp->status2 = count;
 232                sp_xmit_on_air((unsigned long)sp);
 233        }
 234
 235        return;
 236
 237out_drop:
 238        sp->dev->stats.tx_dropped++;
 239        netif_start_queue(sp->dev);
 240        if (net_ratelimit())
 241                printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
 242}
 243
 244/* Encapsulate an IP datagram and kick it into a TTY queue. */
 245
 246static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
 247{
 248        struct sixpack *sp = netdev_priv(dev);
 249
 250        if (skb->protocol == htons(ETH_P_IP))
 251                return ax25_ip_xmit(skb);
 252
 253        spin_lock_bh(&sp->lock);
 254        /* We were not busy, so we are now... :-) */
 255        netif_stop_queue(dev);
 256        dev->stats.tx_bytes += skb->len;
 257        sp_encaps(sp, skb->data, skb->len);
 258        spin_unlock_bh(&sp->lock);
 259
 260        dev_kfree_skb(skb);
 261
 262        return NETDEV_TX_OK;
 263}
 264
 265static int sp_open_dev(struct net_device *dev)
 266{
 267        struct sixpack *sp = netdev_priv(dev);
 268
 269        if (sp->tty == NULL)
 270                return -ENODEV;
 271        return 0;
 272}
 273
 274/* Close the low-level part of the 6pack channel. */
 275static int sp_close(struct net_device *dev)
 276{
 277        struct sixpack *sp = netdev_priv(dev);
 278
 279        spin_lock_bh(&sp->lock);
 280        if (sp->tty) {
 281                /* TTY discipline is running. */
 282                clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
 283        }
 284        netif_stop_queue(dev);
 285        spin_unlock_bh(&sp->lock);
 286
 287        return 0;
 288}
 289
 290static int sp_set_mac_address(struct net_device *dev, void *addr)
 291{
 292        struct sockaddr_ax25 *sa = addr;
 293
 294        netif_tx_lock_bh(dev);
 295        netif_addr_lock(dev);
 296        memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
 297        netif_addr_unlock(dev);
 298        netif_tx_unlock_bh(dev);
 299
 300        return 0;
 301}
 302
 303static const struct net_device_ops sp_netdev_ops = {
 304        .ndo_open               = sp_open_dev,
 305        .ndo_stop               = sp_close,
 306        .ndo_start_xmit         = sp_xmit,
 307        .ndo_set_mac_address    = sp_set_mac_address,
 308};
 309
 310static void sp_setup(struct net_device *dev)
 311{
 312        /* Finish setting up the DEVICE info. */
 313        dev->netdev_ops         = &sp_netdev_ops;
 314        dev->needs_free_netdev  = true;
 315        dev->mtu                = SIXP_MTU;
 316        dev->hard_header_len    = AX25_MAX_HEADER_LEN;
 317        dev->header_ops         = &ax25_header_ops;
 318
 319        dev->addr_len           = AX25_ADDR_LEN;
 320        dev->type               = ARPHRD_AX25;
 321        dev->tx_queue_len       = 10;
 322
 323        /* Only activated in AX.25 mode */
 324        memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
 325        memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
 326
 327        dev->flags              = 0;
 328}
 329
 330/* Send one completely decapsulated IP datagram to the IP layer. */
 331
 332/*
 333 * This is the routine that sends the received data to the kernel AX.25.
 334 * 'cmd' is the KISS command. For AX.25 data, it is zero.
 335 */
 336
 337static void sp_bump(struct sixpack *sp, char cmd)
 338{
 339        struct sk_buff *skb;
 340        int count;
 341        unsigned char *ptr;
 342
 343        count = sp->rcount + 1;
 344
 345        sp->dev->stats.rx_bytes += count;
 346
 347        if ((skb = dev_alloc_skb(count)) == NULL)
 348                goto out_mem;
 349
 350        ptr = skb_put(skb, count);
 351        *ptr++ = cmd;   /* KISS command */
 352
 353        memcpy(ptr, sp->cooked_buf + 1, count);
 354        skb->protocol = ax25_type_trans(skb, sp->dev);
 355        netif_rx(skb);
 356        sp->dev->stats.rx_packets++;
 357
 358        return;
 359
 360out_mem:
 361        sp->dev->stats.rx_dropped++;
 362}
 363
 364
 365/* ----------------------------------------------------------------------- */
 366
 367/*
 368 * We have a potential race on dereferencing tty->disc_data, because the tty
 369 * layer provides no locking at all - thus one cpu could be running
 370 * sixpack_receive_buf while another calls sixpack_close, which zeroes
 371 * tty->disc_data and frees the memory that sixpack_receive_buf is using.  The
 372 * best way to fix this is to use a rwlock in the tty struct, but for now we
 373 * use a single global rwlock for all ttys in ppp line discipline.
 374 */
 375static DEFINE_RWLOCK(disc_data_lock);
 376                                                                                
 377static struct sixpack *sp_get(struct tty_struct *tty)
 378{
 379        struct sixpack *sp;
 380
 381        read_lock(&disc_data_lock);
 382        sp = tty->disc_data;
 383        if (sp)
 384                atomic_inc(&sp->refcnt);
 385        read_unlock(&disc_data_lock);
 386
 387        return sp;
 388}
 389
 390static void sp_put(struct sixpack *sp)
 391{
 392        if (atomic_dec_and_test(&sp->refcnt))
 393                up(&sp->dead_sem);
 394}
 395
 396/*
 397 * Called by the TTY driver when there's room for more data.  If we have
 398 * more packets to send, we send them here.
 399 */
 400static void sixpack_write_wakeup(struct tty_struct *tty)
 401{
 402        struct sixpack *sp = sp_get(tty);
 403        int actual;
 404
 405        if (!sp)
 406                return;
 407        if (sp->xleft <= 0)  {
 408                /* Now serial buffer is almost free & we can start
 409                 * transmission of another packet */
 410                sp->dev->stats.tx_packets++;
 411                clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 412                sp->tx_enable = 0;
 413                netif_wake_queue(sp->dev);
 414                goto out;
 415        }
 416
 417        if (sp->tx_enable) {
 418                actual = tty->ops->write(tty, sp->xhead, sp->xleft);
 419                sp->xleft -= actual;
 420                sp->xhead += actual;
 421        }
 422
 423out:
 424        sp_put(sp);
 425}
 426
 427/* ----------------------------------------------------------------------- */
 428
 429/*
 430 * Handle the 'receiver data ready' interrupt.
 431 * This function is called by the tty module in the kernel when
 432 * a block of 6pack data has been received, which can now be decapsulated
 433 * and sent on to some IP layer for further processing.
 434 */
 435static void sixpack_receive_buf(struct tty_struct *tty,
 436        const unsigned char *cp, char *fp, int count)
 437{
 438        struct sixpack *sp;
 439        int count1;
 440
 441        if (!count)
 442                return;
 443
 444        sp = sp_get(tty);
 445        if (!sp)
 446                return;
 447
 448        /* Read the characters out of the buffer */
 449        count1 = count;
 450        while (count) {
 451                count--;
 452                if (fp && *fp++) {
 453                        if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
 454                                sp->dev->stats.rx_errors++;
 455                        continue;
 456                }
 457        }
 458        sixpack_decode(sp, cp, count1);
 459
 460        sp_put(sp);
 461        tty_unthrottle(tty);
 462}
 463
 464/*
 465 * Try to resync the TNC. Called by the resync timer defined in
 466 * decode_prio_command
 467 */
 468
 469#define TNC_UNINITIALIZED       0
 470#define TNC_UNSYNC_STARTUP      1
 471#define TNC_UNSYNCED            2
 472#define TNC_IN_SYNC             3
 473
 474static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
 475{
 476        char *msg;
 477
 478        switch (new_tnc_state) {
 479        default:                        /* gcc oh piece-o-crap ... */
 480        case TNC_UNSYNC_STARTUP:
 481                msg = "Synchronizing with TNC";
 482                break;
 483        case TNC_UNSYNCED:
 484                msg = "Lost synchronization with TNC\n";
 485                break;
 486        case TNC_IN_SYNC:
 487                msg = "Found TNC";
 488                break;
 489        }
 490
 491        sp->tnc_state = new_tnc_state;
 492        printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
 493}
 494
 495static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
 496{
 497        int old_tnc_state = sp->tnc_state;
 498
 499        if (old_tnc_state != new_tnc_state)
 500                __tnc_set_sync_state(sp, new_tnc_state);
 501}
 502
 503static void resync_tnc(unsigned long channel)
 504{
 505        struct sixpack *sp = (struct sixpack *) channel;
 506        static char resync_cmd = 0xe8;
 507
 508        /* clear any data that might have been received */
 509
 510        sp->rx_count = 0;
 511        sp->rx_count_cooked = 0;
 512
 513        /* reset state machine */
 514
 515        sp->status = 1;
 516        sp->status1 = 1;
 517        sp->status2 = 0;
 518
 519        /* resync the TNC */
 520
 521        sp->led_state = 0x60;
 522        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 523        sp->tty->ops->write(sp->tty, &resync_cmd, 1);
 524
 525
 526        /* Start resync timer again -- the TNC might be still absent */
 527
 528        del_timer(&sp->resync_t);
 529        sp->resync_t.data       = (unsigned long) sp;
 530        sp->resync_t.function   = resync_tnc;
 531        sp->resync_t.expires    = jiffies + SIXP_RESYNC_TIMEOUT;
 532        add_timer(&sp->resync_t);
 533}
 534
 535static inline int tnc_init(struct sixpack *sp)
 536{
 537        unsigned char inbyte = 0xe8;
 538
 539        tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
 540
 541        sp->tty->ops->write(sp->tty, &inbyte, 1);
 542
 543        del_timer(&sp->resync_t);
 544        sp->resync_t.data = (unsigned long) sp;
 545        sp->resync_t.function = resync_tnc;
 546        sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
 547        add_timer(&sp->resync_t);
 548
 549        return 0;
 550}
 551
 552/*
 553 * Open the high-level part of the 6pack channel.
 554 * This function is called by the TTY module when the
 555 * 6pack line discipline is called for.  Because we are
 556 * sure the tty line exists, we only have to link it to
 557 * a free 6pcack channel...
 558 */
 559static int sixpack_open(struct tty_struct *tty)
 560{
 561        char *rbuff = NULL, *xbuff = NULL;
 562        struct net_device *dev;
 563        struct sixpack *sp;
 564        unsigned long len;
 565        int err = 0;
 566
 567        if (!capable(CAP_NET_ADMIN))
 568                return -EPERM;
 569        if (tty->ops->write == NULL)
 570                return -EOPNOTSUPP;
 571
 572        dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
 573                           sp_setup);
 574        if (!dev) {
 575                err = -ENOMEM;
 576                goto out;
 577        }
 578
 579        sp = netdev_priv(dev);
 580        sp->dev = dev;
 581
 582        spin_lock_init(&sp->lock);
 583        atomic_set(&sp->refcnt, 1);
 584        sema_init(&sp->dead_sem, 0);
 585
 586        /* !!! length of the buffers. MTU is IP MTU, not PACLEN!  */
 587
 588        len = dev->mtu * 2;
 589
 590        rbuff = kmalloc(len + 4, GFP_KERNEL);
 591        xbuff = kmalloc(len + 4, GFP_KERNEL);
 592
 593        if (rbuff == NULL || xbuff == NULL) {
 594                err = -ENOBUFS;
 595                goto out_free;
 596        }
 597
 598        spin_lock_bh(&sp->lock);
 599
 600        sp->tty = tty;
 601
 602        sp->rbuff       = rbuff;
 603        sp->xbuff       = xbuff;
 604
 605        sp->mtu         = AX25_MTU + 73;
 606        sp->buffsize    = len;
 607        sp->rcount      = 0;
 608        sp->rx_count    = 0;
 609        sp->rx_count_cooked = 0;
 610        sp->xleft       = 0;
 611
 612        sp->flags       = 0;            /* Clear ESCAPE & ERROR flags */
 613
 614        sp->duplex      = 0;
 615        sp->tx_delay    = SIXP_TXDELAY;
 616        sp->persistence = SIXP_PERSIST;
 617        sp->slottime    = SIXP_SLOTTIME;
 618        sp->led_state   = 0x60;
 619        sp->status      = 1;
 620        sp->status1     = 1;
 621        sp->status2     = 0;
 622        sp->tx_enable   = 0;
 623
 624        netif_start_queue(dev);
 625
 626        init_timer(&sp->tx_t);
 627        sp->tx_t.function = sp_xmit_on_air;
 628        sp->tx_t.data = (unsigned long) sp;
 629
 630        init_timer(&sp->resync_t);
 631
 632        spin_unlock_bh(&sp->lock);
 633
 634        /* Done.  We have linked the TTY line to a channel. */
 635        tty->disc_data = sp;
 636        tty->receive_room = 65536;
 637
 638        /* Now we're ready to register. */
 639        err = register_netdev(dev);
 640        if (err)
 641                goto out_free;
 642
 643        tnc_init(sp);
 644
 645        return 0;
 646
 647out_free:
 648        kfree(xbuff);
 649        kfree(rbuff);
 650
 651        free_netdev(dev);
 652
 653out:
 654        return err;
 655}
 656
 657
 658/*
 659 * Close down a 6pack channel.
 660 * This means flushing out any pending queues, and then restoring the
 661 * TTY line discipline to what it was before it got hooked to 6pack
 662 * (which usually is TTY again).
 663 */
 664static void sixpack_close(struct tty_struct *tty)
 665{
 666        struct sixpack *sp;
 667
 668        write_lock_bh(&disc_data_lock);
 669        sp = tty->disc_data;
 670        tty->disc_data = NULL;
 671        write_unlock_bh(&disc_data_lock);
 672        if (!sp)
 673                return;
 674
 675        /*
 676         * We have now ensured that nobody can start using ap from now on, but
 677         * we have to wait for all existing users to finish.
 678         */
 679        if (!atomic_dec_and_test(&sp->refcnt))
 680                down(&sp->dead_sem);
 681
 682        /* We must stop the queue to avoid potentially scribbling
 683         * on the free buffers. The sp->dead_sem is not sufficient
 684         * to protect us from sp->xbuff access.
 685         */
 686        netif_stop_queue(sp->dev);
 687
 688        del_timer_sync(&sp->tx_t);
 689        del_timer_sync(&sp->resync_t);
 690
 691        /* Free all 6pack frame buffers. */
 692        kfree(sp->rbuff);
 693        kfree(sp->xbuff);
 694
 695        unregister_netdev(sp->dev);
 696}
 697
 698/* Perform I/O control on an active 6pack channel. */
 699static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
 700        unsigned int cmd, unsigned long arg)
 701{
 702        struct sixpack *sp = sp_get(tty);
 703        struct net_device *dev;
 704        unsigned int tmp, err;
 705
 706        if (!sp)
 707                return -ENXIO;
 708        dev = sp->dev;
 709
 710        switch(cmd) {
 711        case SIOCGIFNAME:
 712                err = copy_to_user((void __user *) arg, dev->name,
 713                                   strlen(dev->name) + 1) ? -EFAULT : 0;
 714                break;
 715
 716        case SIOCGIFENCAP:
 717                err = put_user(0, (int __user *) arg);
 718                break;
 719
 720        case SIOCSIFENCAP:
 721                if (get_user(tmp, (int __user *) arg)) {
 722                        err = -EFAULT;
 723                        break;
 724                }
 725
 726                sp->mode = tmp;
 727                dev->addr_len        = AX25_ADDR_LEN;
 728                dev->hard_header_len = AX25_KISS_HEADER_LEN +
 729                                       AX25_MAX_HEADER_LEN + 3;
 730                dev->type            = ARPHRD_AX25;
 731
 732                err = 0;
 733                break;
 734
 735         case SIOCSIFHWADDR: {
 736                char addr[AX25_ADDR_LEN];
 737
 738                if (copy_from_user(&addr,
 739                                   (void __user *) arg, AX25_ADDR_LEN)) {
 740                                err = -EFAULT;
 741                                break;
 742                        }
 743
 744                        netif_tx_lock_bh(dev);
 745                        memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
 746                        netif_tx_unlock_bh(dev);
 747
 748                        err = 0;
 749                        break;
 750                }
 751
 752        default:
 753                err = tty_mode_ioctl(tty, file, cmd, arg);
 754        }
 755
 756        sp_put(sp);
 757
 758        return err;
 759}
 760
 761#ifdef CONFIG_COMPAT
 762static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
 763                                unsigned int cmd, unsigned long arg)
 764{
 765        switch (cmd) {
 766        case SIOCGIFNAME:
 767        case SIOCGIFENCAP:
 768        case SIOCSIFENCAP:
 769        case SIOCSIFHWADDR:
 770                return sixpack_ioctl(tty, file, cmd,
 771                                (unsigned long)compat_ptr(arg));
 772        }
 773
 774        return -ENOIOCTLCMD;
 775}
 776#endif
 777
 778static struct tty_ldisc_ops sp_ldisc = {
 779        .owner          = THIS_MODULE,
 780        .magic          = TTY_LDISC_MAGIC,
 781        .name           = "6pack",
 782        .open           = sixpack_open,
 783        .close          = sixpack_close,
 784        .ioctl          = sixpack_ioctl,
 785#ifdef CONFIG_COMPAT
 786        .compat_ioctl   = sixpack_compat_ioctl,
 787#endif
 788        .receive_buf    = sixpack_receive_buf,
 789        .write_wakeup   = sixpack_write_wakeup,
 790};
 791
 792/* Initialize 6pack control device -- register 6pack line discipline */
 793
 794static const char msg_banner[]  __initconst = KERN_INFO \
 795        "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
 796static const char msg_regfail[] __initconst = KERN_ERR  \
 797        "6pack: can't register line discipline (err = %d)\n";
 798
 799static int __init sixpack_init_driver(void)
 800{
 801        int status;
 802
 803        printk(msg_banner);
 804
 805        /* Register the provided line protocol discipline */
 806        if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
 807                printk(msg_regfail, status);
 808
 809        return status;
 810}
 811
 812static const char msg_unregfail[] = KERN_ERR \
 813        "6pack: can't unregister line discipline (err = %d)\n";
 814
 815static void __exit sixpack_exit_driver(void)
 816{
 817        int ret;
 818
 819        if ((ret = tty_unregister_ldisc(N_6PACK)))
 820                printk(msg_unregfail, ret);
 821}
 822
 823/* encode an AX.25 packet into 6pack */
 824
 825static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
 826        int length, unsigned char tx_delay)
 827{
 828        int count = 0;
 829        unsigned char checksum = 0, buf[400];
 830        int raw_count = 0;
 831
 832        tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
 833        tx_buf_raw[raw_count++] = SIXP_SEOF;
 834
 835        buf[0] = tx_delay;
 836        for (count = 1; count < length; count++)
 837                buf[count] = tx_buf[count];
 838
 839        for (count = 0; count < length; count++)
 840                checksum += buf[count];
 841        buf[length] = (unsigned char) 0xff - checksum;
 842
 843        for (count = 0; count <= length; count++) {
 844                if ((count % 3) == 0) {
 845                        tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
 846                        tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
 847                } else if ((count % 3) == 1) {
 848                        tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
 849                        tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
 850                } else {
 851                        tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
 852                        tx_buf_raw[raw_count++] = (buf[count] >> 2);
 853                }
 854        }
 855        if ((length % 3) != 2)
 856                raw_count++;
 857        tx_buf_raw[raw_count++] = SIXP_SEOF;
 858        return raw_count;
 859}
 860
 861/* decode 4 sixpack-encoded bytes into 3 data bytes */
 862
 863static void decode_data(struct sixpack *sp, unsigned char inbyte)
 864{
 865        unsigned char *buf;
 866
 867        if (sp->rx_count != 3) {
 868                sp->raw_buf[sp->rx_count++] = inbyte;
 869
 870                return;
 871        }
 872
 873        buf = sp->raw_buf;
 874        sp->cooked_buf[sp->rx_count_cooked++] =
 875                buf[0] | ((buf[1] << 2) & 0xc0);
 876        sp->cooked_buf[sp->rx_count_cooked++] =
 877                (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
 878        sp->cooked_buf[sp->rx_count_cooked++] =
 879                (buf[2] & 0x03) | (inbyte << 2);
 880        sp->rx_count = 0;
 881}
 882
 883/* identify and execute a 6pack priority command byte */
 884
 885static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
 886{
 887        unsigned char channel;
 888        int actual;
 889
 890        channel = cmd & SIXP_CHN_MASK;
 891        if ((cmd & SIXP_PRIO_DATA_MASK) != 0) {     /* idle ? */
 892
 893        /* RX and DCD flags can only be set in the same prio command,
 894           if the DCD flag has been set without the RX flag in the previous
 895           prio command. If DCD has not been set before, something in the
 896           transmission has gone wrong. In this case, RX and DCD are
 897           cleared in order to prevent the decode_data routine from
 898           reading further data that might be corrupt. */
 899
 900                if (((sp->status & SIXP_DCD_MASK) == 0) &&
 901                        ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
 902                                if (sp->status != 1)
 903                                        printk(KERN_DEBUG "6pack: protocol violation\n");
 904                                else
 905                                        sp->status = 0;
 906                                cmd &= ~SIXP_RX_DCD_MASK;
 907                }
 908                sp->status = cmd & SIXP_PRIO_DATA_MASK;
 909        } else { /* output watchdog char if idle */
 910                if ((sp->status2 != 0) && (sp->duplex == 1)) {
 911                        sp->led_state = 0x70;
 912                        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 913                        sp->tx_enable = 1;
 914                        actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
 915                        sp->xleft -= actual;
 916                        sp->xhead += actual;
 917                        sp->led_state = 0x60;
 918                        sp->status2 = 0;
 919
 920                }
 921        }
 922
 923        /* needed to trigger the TNC watchdog */
 924        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 925
 926        /* if the state byte has been received, the TNC is present,
 927           so the resync timer can be reset. */
 928
 929        if (sp->tnc_state == TNC_IN_SYNC) {
 930                del_timer(&sp->resync_t);
 931                sp->resync_t.data       = (unsigned long) sp;
 932                sp->resync_t.function   = resync_tnc;
 933                sp->resync_t.expires    = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
 934                add_timer(&sp->resync_t);
 935        }
 936
 937        sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
 938}
 939
 940/* identify and execute a standard 6pack command byte */
 941
 942static void decode_std_command(struct sixpack *sp, unsigned char cmd)
 943{
 944        unsigned char checksum = 0, rest = 0, channel;
 945        short i;
 946
 947        channel = cmd & SIXP_CHN_MASK;
 948        switch (cmd & SIXP_CMD_MASK) {     /* normal command */
 949        case SIXP_SEOF:
 950                if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
 951                        if ((sp->status & SIXP_RX_DCD_MASK) ==
 952                                SIXP_RX_DCD_MASK) {
 953                                sp->led_state = 0x68;
 954                                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 955                        }
 956                } else {
 957                        sp->led_state = 0x60;
 958                        /* fill trailing bytes with zeroes */
 959                        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 960                        rest = sp->rx_count;
 961                        if (rest != 0)
 962                                 for (i = rest; i <= 3; i++)
 963                                        decode_data(sp, 0);
 964                        if (rest == 2)
 965                                sp->rx_count_cooked -= 2;
 966                        else if (rest == 3)
 967                                sp->rx_count_cooked -= 1;
 968                        for (i = 0; i < sp->rx_count_cooked; i++)
 969                                checksum += sp->cooked_buf[i];
 970                        if (checksum != SIXP_CHKSUM) {
 971                                printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
 972                        } else {
 973                                sp->rcount = sp->rx_count_cooked-2;
 974                                sp_bump(sp, 0);
 975                        }
 976                        sp->rx_count_cooked = 0;
 977                }
 978                break;
 979        case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
 980                break;
 981        case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
 982                break;
 983        case SIXP_RX_BUF_OVL:
 984                printk(KERN_DEBUG "6pack: RX buffer overflow\n");
 985        }
 986}
 987
 988/* decode a 6pack packet */
 989
 990static void
 991sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
 992{
 993        unsigned char inbyte;
 994        int count1;
 995
 996        for (count1 = 0; count1 < count; count1++) {
 997                inbyte = pre_rbuff[count1];
 998                if (inbyte == SIXP_FOUND_TNC) {
 999                        tnc_set_sync_state(sp, TNC_IN_SYNC);
1000                        del_timer(&sp->resync_t);
1001                }
1002                if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1003                        decode_prio_command(sp, inbyte);
1004                else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1005                        decode_std_command(sp, inbyte);
1006                else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1007                        decode_data(sp, inbyte);
1008        }
1009}
1010
1011MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1012MODULE_DESCRIPTION("6pack driver for AX.25");
1013MODULE_LICENSE("GPL");
1014MODULE_ALIAS_LDISC(N_6PACK);
1015
1016module_init(sixpack_init_driver);
1017module_exit(sixpack_exit_driver);
1018