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/refcount.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        refcount_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(struct timer_list *t)
 140{
 141        struct sixpack *sp = from_timer(sp, t, tx_t);
 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(&sp->tx_t);
 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                refcount_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 (refcount_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(struct timer_list *t)
 504{
 505        struct sixpack *sp = from_timer(sp, t, resync_t);
 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.expires    = jiffies + SIXP_RESYNC_TIMEOUT;
 530        add_timer(&sp->resync_t);
 531}
 532
 533static inline int tnc_init(struct sixpack *sp)
 534{
 535        unsigned char inbyte = 0xe8;
 536
 537        tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
 538
 539        sp->tty->ops->write(sp->tty, &inbyte, 1);
 540
 541        del_timer(&sp->resync_t);
 542        sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
 543        add_timer(&sp->resync_t);
 544
 545        return 0;
 546}
 547
 548/*
 549 * Open the high-level part of the 6pack channel.
 550 * This function is called by the TTY module when the
 551 * 6pack line discipline is called for.  Because we are
 552 * sure the tty line exists, we only have to link it to
 553 * a free 6pcack channel...
 554 */
 555static int sixpack_open(struct tty_struct *tty)
 556{
 557        char *rbuff = NULL, *xbuff = NULL;
 558        struct net_device *dev;
 559        struct sixpack *sp;
 560        unsigned long len;
 561        int err = 0;
 562
 563        if (!capable(CAP_NET_ADMIN))
 564                return -EPERM;
 565        if (tty->ops->write == NULL)
 566                return -EOPNOTSUPP;
 567
 568        dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
 569                           sp_setup);
 570        if (!dev) {
 571                err = -ENOMEM;
 572                goto out;
 573        }
 574
 575        sp = netdev_priv(dev);
 576        sp->dev = dev;
 577
 578        spin_lock_init(&sp->lock);
 579        refcount_set(&sp->refcnt, 1);
 580        sema_init(&sp->dead_sem, 0);
 581
 582        /* !!! length of the buffers. MTU is IP MTU, not PACLEN!  */
 583
 584        len = dev->mtu * 2;
 585
 586        rbuff = kmalloc(len + 4, GFP_KERNEL);
 587        xbuff = kmalloc(len + 4, GFP_KERNEL);
 588
 589        if (rbuff == NULL || xbuff == NULL) {
 590                err = -ENOBUFS;
 591                goto out_free;
 592        }
 593
 594        spin_lock_bh(&sp->lock);
 595
 596        sp->tty = tty;
 597
 598        sp->rbuff       = rbuff;
 599        sp->xbuff       = xbuff;
 600
 601        sp->mtu         = AX25_MTU + 73;
 602        sp->buffsize    = len;
 603        sp->rcount      = 0;
 604        sp->rx_count    = 0;
 605        sp->rx_count_cooked = 0;
 606        sp->xleft       = 0;
 607
 608        sp->flags       = 0;            /* Clear ESCAPE & ERROR flags */
 609
 610        sp->duplex      = 0;
 611        sp->tx_delay    = SIXP_TXDELAY;
 612        sp->persistence = SIXP_PERSIST;
 613        sp->slottime    = SIXP_SLOTTIME;
 614        sp->led_state   = 0x60;
 615        sp->status      = 1;
 616        sp->status1     = 1;
 617        sp->status2     = 0;
 618        sp->tx_enable   = 0;
 619
 620        netif_start_queue(dev);
 621
 622        timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
 623
 624        timer_setup(&sp->resync_t, resync_tnc, 0);
 625
 626        spin_unlock_bh(&sp->lock);
 627
 628        /* Done.  We have linked the TTY line to a channel. */
 629        tty->disc_data = sp;
 630        tty->receive_room = 65536;
 631
 632        /* Now we're ready to register. */
 633        err = register_netdev(dev);
 634        if (err)
 635                goto out_free;
 636
 637        tnc_init(sp);
 638
 639        return 0;
 640
 641out_free:
 642        kfree(xbuff);
 643        kfree(rbuff);
 644
 645        free_netdev(dev);
 646
 647out:
 648        return err;
 649}
 650
 651
 652/*
 653 * Close down a 6pack channel.
 654 * This means flushing out any pending queues, and then restoring the
 655 * TTY line discipline to what it was before it got hooked to 6pack
 656 * (which usually is TTY again).
 657 */
 658static void sixpack_close(struct tty_struct *tty)
 659{
 660        struct sixpack *sp;
 661
 662        write_lock_bh(&disc_data_lock);
 663        sp = tty->disc_data;
 664        tty->disc_data = NULL;
 665        write_unlock_bh(&disc_data_lock);
 666        if (!sp)
 667                return;
 668
 669        /*
 670         * We have now ensured that nobody can start using ap from now on, but
 671         * we have to wait for all existing users to finish.
 672         */
 673        if (!refcount_dec_and_test(&sp->refcnt))
 674                down(&sp->dead_sem);
 675
 676        /* We must stop the queue to avoid potentially scribbling
 677         * on the free buffers. The sp->dead_sem is not sufficient
 678         * to protect us from sp->xbuff access.
 679         */
 680        netif_stop_queue(sp->dev);
 681
 682        del_timer_sync(&sp->tx_t);
 683        del_timer_sync(&sp->resync_t);
 684
 685        /* Free all 6pack frame buffers. */
 686        kfree(sp->rbuff);
 687        kfree(sp->xbuff);
 688
 689        unregister_netdev(sp->dev);
 690}
 691
 692/* Perform I/O control on an active 6pack channel. */
 693static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
 694        unsigned int cmd, unsigned long arg)
 695{
 696        struct sixpack *sp = sp_get(tty);
 697        struct net_device *dev;
 698        unsigned int tmp, err;
 699
 700        if (!sp)
 701                return -ENXIO;
 702        dev = sp->dev;
 703
 704        switch(cmd) {
 705        case SIOCGIFNAME:
 706                err = copy_to_user((void __user *) arg, dev->name,
 707                                   strlen(dev->name) + 1) ? -EFAULT : 0;
 708                break;
 709
 710        case SIOCGIFENCAP:
 711                err = put_user(0, (int __user *) arg);
 712                break;
 713
 714        case SIOCSIFENCAP:
 715                if (get_user(tmp, (int __user *) arg)) {
 716                        err = -EFAULT;
 717                        break;
 718                }
 719
 720                sp->mode = tmp;
 721                dev->addr_len        = AX25_ADDR_LEN;
 722                dev->hard_header_len = AX25_KISS_HEADER_LEN +
 723                                       AX25_MAX_HEADER_LEN + 3;
 724                dev->type            = ARPHRD_AX25;
 725
 726                err = 0;
 727                break;
 728
 729         case SIOCSIFHWADDR: {
 730                char addr[AX25_ADDR_LEN];
 731
 732                if (copy_from_user(&addr,
 733                                   (void __user *) arg, AX25_ADDR_LEN)) {
 734                                err = -EFAULT;
 735                                break;
 736                        }
 737
 738                        netif_tx_lock_bh(dev);
 739                        memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
 740                        netif_tx_unlock_bh(dev);
 741
 742                        err = 0;
 743                        break;
 744                }
 745
 746        default:
 747                err = tty_mode_ioctl(tty, file, cmd, arg);
 748        }
 749
 750        sp_put(sp);
 751
 752        return err;
 753}
 754
 755#ifdef CONFIG_COMPAT
 756static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
 757                                unsigned int cmd, unsigned long arg)
 758{
 759        switch (cmd) {
 760        case SIOCGIFNAME:
 761        case SIOCGIFENCAP:
 762        case SIOCSIFENCAP:
 763        case SIOCSIFHWADDR:
 764                return sixpack_ioctl(tty, file, cmd,
 765                                (unsigned long)compat_ptr(arg));
 766        }
 767
 768        return -ENOIOCTLCMD;
 769}
 770#endif
 771
 772static struct tty_ldisc_ops sp_ldisc = {
 773        .owner          = THIS_MODULE,
 774        .magic          = TTY_LDISC_MAGIC,
 775        .name           = "6pack",
 776        .open           = sixpack_open,
 777        .close          = sixpack_close,
 778        .ioctl          = sixpack_ioctl,
 779#ifdef CONFIG_COMPAT
 780        .compat_ioctl   = sixpack_compat_ioctl,
 781#endif
 782        .receive_buf    = sixpack_receive_buf,
 783        .write_wakeup   = sixpack_write_wakeup,
 784};
 785
 786/* Initialize 6pack control device -- register 6pack line discipline */
 787
 788static const char msg_banner[]  __initconst = KERN_INFO \
 789        "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
 790static const char msg_regfail[] __initconst = KERN_ERR  \
 791        "6pack: can't register line discipline (err = %d)\n";
 792
 793static int __init sixpack_init_driver(void)
 794{
 795        int status;
 796
 797        printk(msg_banner);
 798
 799        /* Register the provided line protocol discipline */
 800        if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
 801                printk(msg_regfail, status);
 802
 803        return status;
 804}
 805
 806static const char msg_unregfail[] = KERN_ERR \
 807        "6pack: can't unregister line discipline (err = %d)\n";
 808
 809static void __exit sixpack_exit_driver(void)
 810{
 811        int ret;
 812
 813        if ((ret = tty_unregister_ldisc(N_6PACK)))
 814                printk(msg_unregfail, ret);
 815}
 816
 817/* encode an AX.25 packet into 6pack */
 818
 819static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
 820        int length, unsigned char tx_delay)
 821{
 822        int count = 0;
 823        unsigned char checksum = 0, buf[400];
 824        int raw_count = 0;
 825
 826        tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
 827        tx_buf_raw[raw_count++] = SIXP_SEOF;
 828
 829        buf[0] = tx_delay;
 830        for (count = 1; count < length; count++)
 831                buf[count] = tx_buf[count];
 832
 833        for (count = 0; count < length; count++)
 834                checksum += buf[count];
 835        buf[length] = (unsigned char) 0xff - checksum;
 836
 837        for (count = 0; count <= length; count++) {
 838                if ((count % 3) == 0) {
 839                        tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
 840                        tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
 841                } else if ((count % 3) == 1) {
 842                        tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
 843                        tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
 844                } else {
 845                        tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
 846                        tx_buf_raw[raw_count++] = (buf[count] >> 2);
 847                }
 848        }
 849        if ((length % 3) != 2)
 850                raw_count++;
 851        tx_buf_raw[raw_count++] = SIXP_SEOF;
 852        return raw_count;
 853}
 854
 855/* decode 4 sixpack-encoded bytes into 3 data bytes */
 856
 857static void decode_data(struct sixpack *sp, unsigned char inbyte)
 858{
 859        unsigned char *buf;
 860
 861        if (sp->rx_count != 3) {
 862                sp->raw_buf[sp->rx_count++] = inbyte;
 863
 864                return;
 865        }
 866
 867        buf = sp->raw_buf;
 868        sp->cooked_buf[sp->rx_count_cooked++] =
 869                buf[0] | ((buf[1] << 2) & 0xc0);
 870        sp->cooked_buf[sp->rx_count_cooked++] =
 871                (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
 872        sp->cooked_buf[sp->rx_count_cooked++] =
 873                (buf[2] & 0x03) | (inbyte << 2);
 874        sp->rx_count = 0;
 875}
 876
 877/* identify and execute a 6pack priority command byte */
 878
 879static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
 880{
 881        unsigned char channel;
 882        int actual;
 883
 884        channel = cmd & SIXP_CHN_MASK;
 885        if ((cmd & SIXP_PRIO_DATA_MASK) != 0) {     /* idle ? */
 886
 887        /* RX and DCD flags can only be set in the same prio command,
 888           if the DCD flag has been set without the RX flag in the previous
 889           prio command. If DCD has not been set before, something in the
 890           transmission has gone wrong. In this case, RX and DCD are
 891           cleared in order to prevent the decode_data routine from
 892           reading further data that might be corrupt. */
 893
 894                if (((sp->status & SIXP_DCD_MASK) == 0) &&
 895                        ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
 896                                if (sp->status != 1)
 897                                        printk(KERN_DEBUG "6pack: protocol violation\n");
 898                                else
 899                                        sp->status = 0;
 900                                cmd &= ~SIXP_RX_DCD_MASK;
 901                }
 902                sp->status = cmd & SIXP_PRIO_DATA_MASK;
 903        } else { /* output watchdog char if idle */
 904                if ((sp->status2 != 0) && (sp->duplex == 1)) {
 905                        sp->led_state = 0x70;
 906                        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 907                        sp->tx_enable = 1;
 908                        actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
 909                        sp->xleft -= actual;
 910                        sp->xhead += actual;
 911                        sp->led_state = 0x60;
 912                        sp->status2 = 0;
 913
 914                }
 915        }
 916
 917        /* needed to trigger the TNC watchdog */
 918        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 919
 920        /* if the state byte has been received, the TNC is present,
 921           so the resync timer can be reset. */
 922
 923        if (sp->tnc_state == TNC_IN_SYNC) {
 924                del_timer(&sp->resync_t);
 925                sp->resync_t.expires    = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
 926                add_timer(&sp->resync_t);
 927        }
 928
 929        sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
 930}
 931
 932/* identify and execute a standard 6pack command byte */
 933
 934static void decode_std_command(struct sixpack *sp, unsigned char cmd)
 935{
 936        unsigned char checksum = 0, rest = 0, channel;
 937        short i;
 938
 939        channel = cmd & SIXP_CHN_MASK;
 940        switch (cmd & SIXP_CMD_MASK) {     /* normal command */
 941        case SIXP_SEOF:
 942                if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
 943                        if ((sp->status & SIXP_RX_DCD_MASK) ==
 944                                SIXP_RX_DCD_MASK) {
 945                                sp->led_state = 0x68;
 946                                sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 947                        }
 948                } else {
 949                        sp->led_state = 0x60;
 950                        /* fill trailing bytes with zeroes */
 951                        sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 952                        rest = sp->rx_count;
 953                        if (rest != 0)
 954                                 for (i = rest; i <= 3; i++)
 955                                        decode_data(sp, 0);
 956                        if (rest == 2)
 957                                sp->rx_count_cooked -= 2;
 958                        else if (rest == 3)
 959                                sp->rx_count_cooked -= 1;
 960                        for (i = 0; i < sp->rx_count_cooked; i++)
 961                                checksum += sp->cooked_buf[i];
 962                        if (checksum != SIXP_CHKSUM) {
 963                                printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
 964                        } else {
 965                                sp->rcount = sp->rx_count_cooked-2;
 966                                sp_bump(sp, 0);
 967                        }
 968                        sp->rx_count_cooked = 0;
 969                }
 970                break;
 971        case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
 972                break;
 973        case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
 974                break;
 975        case SIXP_RX_BUF_OVL:
 976                printk(KERN_DEBUG "6pack: RX buffer overflow\n");
 977        }
 978}
 979
 980/* decode a 6pack packet */
 981
 982static void
 983sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
 984{
 985        unsigned char inbyte;
 986        int count1;
 987
 988        for (count1 = 0; count1 < count; count1++) {
 989                inbyte = pre_rbuff[count1];
 990                if (inbyte == SIXP_FOUND_TNC) {
 991                        tnc_set_sync_state(sp, TNC_IN_SYNC);
 992                        del_timer(&sp->resync_t);
 993                }
 994                if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
 995                        decode_prio_command(sp, inbyte);
 996                else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
 997                        decode_std_command(sp, inbyte);
 998                else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
 999                        decode_data(sp, inbyte);
1000        }
1001}
1002
1003MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1004MODULE_DESCRIPTION("6pack driver for AX.25");
1005MODULE_LICENSE("GPL");
1006MODULE_ALIAS_LDISC(N_6PACK);
1007
1008module_init(sixpack_init_driver);
1009module_exit(sixpack_exit_driver);
1010