drivers/net/hamradio/6pack.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
sp_xmit_on_air
sp_encaps
sp_xmit
sp_open_dev
sp_close
sp_set_mac_address
sp_setup
sp_bump
sp_get
sp_put
sixpack_write_wakeup
sixpack_receive_buf
__tnc_set_sync_state
tnc_set_sync_state
resync_tnc
tnc_init
sixpack_open
sixpack_close
sixpack_ioctl
sixpack_init_driver
sixpack_exit_driver
encode_sixpack
decode_data
decode_prio_command
decode_std_command
sixpack_decode
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * 6pack.c      This module implements the 6pack protocol for kernel-based
   4  *              devices like TTY. It interfaces between a raw TTY and the
   5  *              kernel's AX.25 protocol layers.
   6  *
   7  * Authors:     Andreas Könsgen <ajk@comnets.uni-bremen.de>
   8  *              Ralf Baechle DL5RB <ralf@linux-mips.org>
   9  *
  10  * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
  11  *
  12  *              Laurence Culhane, <loz@holmes.demon.co.uk>
  13  *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  14  */
  15 
  16 #include <linux/module.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/bitops.h>
  19 #include <linux/string.h>
  20 #include <linux/mm.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/in.h>
  23 #include <linux/tty.h>
  24 #include <linux/errno.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/timer.h>
  27 #include <linux/slab.h>
  28 #include <net/ax25.h>
  29 #include <linux/etherdevice.h>
  30 #include <linux/skbuff.h>
  31 #include <linux/rtnetlink.h>
  32 #include <linux/spinlock.h>
  33 #include <linux/if_arp.h>
  34 #include <linux/init.h>
  35 #include <linux/ip.h>
  36 #include <linux/tcp.h>
  37 #include <linux/semaphore.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 
  81 enum sixpack_flags {
  82         SIXPF_ERROR,    /* Parity, etc. error   */
  83 };
  84 
  85 struct 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 completion       dead;
 125         spinlock_t              lock;
 126 };
 127 
 128 #define AX25_6PACK_HEADER_LEN 0
 129 
 130 static void sixpack_decode(struct sixpack *, const unsigned char[], int);
 131 static 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 
 139 static 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. */
 164 static 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 
 237 out_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 
 246 static 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 
 265 static 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. */
 275 static 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 
 290 static 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 
 303 static 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 
 310 static 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 
 337 static 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 + 1)) == NULL)
 348                 goto out_mem;
 349 
 350         ptr = skb_put(skb, count + 1);
 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 
 360 out_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  */
 375 static DEFINE_RWLOCK(disc_data_lock);
 376                                                                                 
 377 static 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 
 390 static void sp_put(struct sixpack *sp)
 391 {
 392         if (refcount_dec_and_test(&sp->refcnt))
 393                 complete(&sp->dead);
 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  */
 400 static 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 
 423 out:
 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  */
 435 static 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 
 474 static 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 
 495 static 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 
 503 static 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         mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
 528 }
 529 
 530 static inline int tnc_init(struct sixpack *sp)
 531 {
 532         unsigned char inbyte = 0xe8;
 533 
 534         tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
 535 
 536         sp->tty->ops->write(sp->tty, &inbyte, 1);
 537 
 538         mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
 539 
 540         return 0;
 541 }
 542 
 543 /*
 544  * Open the high-level part of the 6pack channel.
 545  * This function is called by the TTY module when the
 546  * 6pack line discipline is called for.  Because we are
 547  * sure the tty line exists, we only have to link it to
 548  * a free 6pcack channel...
 549  */
 550 static int sixpack_open(struct tty_struct *tty)
 551 {
 552         char *rbuff = NULL, *xbuff = NULL;
 553         struct net_device *dev;
 554         struct sixpack *sp;
 555         unsigned long len;
 556         int err = 0;
 557 
 558         if (!capable(CAP_NET_ADMIN))
 559                 return -EPERM;
 560         if (tty->ops->write == NULL)
 561                 return -EOPNOTSUPP;
 562 
 563         dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
 564                            sp_setup);
 565         if (!dev) {
 566                 err = -ENOMEM;
 567                 goto out;
 568         }
 569 
 570         sp = netdev_priv(dev);
 571         sp->dev = dev;
 572 
 573         spin_lock_init(&sp->lock);
 574         refcount_set(&sp->refcnt, 1);
 575         init_completion(&sp->dead);
 576 
 577         /* !!! length of the buffers. MTU is IP MTU, not PACLEN!  */
 578 
 579         len = dev->mtu * 2;
 580 
 581         rbuff = kmalloc(len + 4, GFP_KERNEL);
 582         xbuff = kmalloc(len + 4, GFP_KERNEL);
 583 
 584         if (rbuff == NULL || xbuff == NULL) {
 585                 err = -ENOBUFS;
 586                 goto out_free;
 587         }
 588 
 589         spin_lock_bh(&sp->lock);
 590 
 591         sp->tty = tty;
 592 
 593         sp->rbuff       = rbuff;
 594         sp->xbuff       = xbuff;
 595 
 596         sp->mtu         = AX25_MTU + 73;
 597         sp->buffsize    = len;
 598         sp->rcount      = 0;
 599         sp->rx_count    = 0;
 600         sp->rx_count_cooked = 0;
 601         sp->xleft       = 0;
 602 
 603         sp->flags       = 0;            /* Clear ESCAPE & ERROR flags */
 604 
 605         sp->duplex      = 0;
 606         sp->tx_delay    = SIXP_TXDELAY;
 607         sp->persistence = SIXP_PERSIST;
 608         sp->slottime    = SIXP_SLOTTIME;
 609         sp->led_state   = 0x60;
 610         sp->status      = 1;
 611         sp->status1     = 1;
 612         sp->status2     = 0;
 613         sp->tx_enable   = 0;
 614 
 615         netif_start_queue(dev);
 616 
 617         timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
 618 
 619         timer_setup(&sp->resync_t, resync_tnc, 0);
 620 
 621         spin_unlock_bh(&sp->lock);
 622 
 623         /* Done.  We have linked the TTY line to a channel. */
 624         tty->disc_data = sp;
 625         tty->receive_room = 65536;
 626 
 627         /* Now we're ready to register. */
 628         err = register_netdev(dev);
 629         if (err)
 630                 goto out_free;
 631 
 632         tnc_init(sp);
 633 
 634         return 0;
 635 
 636 out_free:
 637         kfree(xbuff);
 638         kfree(rbuff);
 639 
 640         free_netdev(dev);
 641 
 642 out:
 643         return err;
 644 }
 645 
 646 
 647 /*
 648  * Close down a 6pack channel.
 649  * This means flushing out any pending queues, and then restoring the
 650  * TTY line discipline to what it was before it got hooked to 6pack
 651  * (which usually is TTY again).
 652  */
 653 static void sixpack_close(struct tty_struct *tty)
 654 {
 655         struct sixpack *sp;
 656 
 657         write_lock_irq(&disc_data_lock);
 658         sp = tty->disc_data;
 659         tty->disc_data = NULL;
 660         write_unlock_irq(&disc_data_lock);
 661         if (!sp)
 662                 return;
 663 
 664         /*
 665          * We have now ensured that nobody can start using ap from now on, but
 666          * we have to wait for all existing users to finish.
 667          */
 668         if (!refcount_dec_and_test(&sp->refcnt))
 669                 wait_for_completion(&sp->dead);
 670 
 671         /* We must stop the queue to avoid potentially scribbling
 672          * on the free buffers. The sp->dead completion is not sufficient
 673          * to protect us from sp->xbuff access.
 674          */
 675         netif_stop_queue(sp->dev);
 676 
 677         del_timer_sync(&sp->tx_t);
 678         del_timer_sync(&sp->resync_t);
 679 
 680         /* Free all 6pack frame buffers. */
 681         kfree(sp->rbuff);
 682         kfree(sp->xbuff);
 683 
 684         unregister_netdev(sp->dev);
 685 }
 686 
 687 /* Perform I/O control on an active 6pack channel. */
 688 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
 689         unsigned int cmd, unsigned long arg)
 690 {
 691         struct sixpack *sp = sp_get(tty);
 692         struct net_device *dev;
 693         unsigned int tmp, err;
 694 
 695         if (!sp)
 696                 return -ENXIO;
 697         dev = sp->dev;
 698 
 699         switch(cmd) {
 700         case SIOCGIFNAME:
 701                 err = copy_to_user((void __user *) arg, dev->name,
 702                                    strlen(dev->name) + 1) ? -EFAULT : 0;
 703                 break;
 704 
 705         case SIOCGIFENCAP:
 706                 err = put_user(0, (int __user *) arg);
 707                 break;
 708 
 709         case SIOCSIFENCAP:
 710                 if (get_user(tmp, (int __user *) arg)) {
 711                         err = -EFAULT;
 712                         break;
 713                 }
 714 
 715                 sp->mode = tmp;
 716                 dev->addr_len        = AX25_ADDR_LEN;
 717                 dev->hard_header_len = AX25_KISS_HEADER_LEN +
 718                                        AX25_MAX_HEADER_LEN + 3;
 719                 dev->type            = ARPHRD_AX25;
 720 
 721                 err = 0;
 722                 break;
 723 
 724          case SIOCSIFHWADDR: {
 725                 char addr[AX25_ADDR_LEN];
 726 
 727                 if (copy_from_user(&addr,
 728                                    (void __user *) arg, AX25_ADDR_LEN)) {
 729                                 err = -EFAULT;
 730                                 break;
 731                         }
 732 
 733                         netif_tx_lock_bh(dev);
 734                         memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
 735                         netif_tx_unlock_bh(dev);
 736 
 737                         err = 0;
 738                         break;
 739                 }
 740 
 741         default:
 742                 err = tty_mode_ioctl(tty, file, cmd, arg);
 743         }
 744 
 745         sp_put(sp);
 746 
 747         return err;
 748 }
 749 
 750 static struct tty_ldisc_ops sp_ldisc = {
 751         .owner          = THIS_MODULE,
 752         .magic          = TTY_LDISC_MAGIC,
 753         .name           = "6pack",
 754         .open           = sixpack_open,
 755         .close          = sixpack_close,
 756         .ioctl          = sixpack_ioctl,
 757         .receive_buf    = sixpack_receive_buf,
 758         .write_wakeup   = sixpack_write_wakeup,
 759 };
 760 
 761 /* Initialize 6pack control device -- register 6pack line discipline */
 762 
 763 static const char msg_banner[]  __initconst = KERN_INFO \
 764         "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
 765 static const char msg_regfail[] __initconst = KERN_ERR  \
 766         "6pack: can't register line discipline (err = %d)\n";
 767 
 768 static int __init sixpack_init_driver(void)
 769 {
 770         int status;
 771 
 772         printk(msg_banner);
 773 
 774         /* Register the provided line protocol discipline */
 775         if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
 776                 printk(msg_regfail, status);
 777 
 778         return status;
 779 }
 780 
 781 static const char msg_unregfail[] = KERN_ERR \
 782         "6pack: can't unregister line discipline (err = %d)\n";
 783 
 784 static void __exit sixpack_exit_driver(void)
 785 {
 786         int ret;
 787 
 788         if ((ret = tty_unregister_ldisc(N_6PACK)))
 789                 printk(msg_unregfail, ret);
 790 }
 791 
 792 /* encode an AX.25 packet into 6pack */
 793 
 794 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
 795         int length, unsigned char tx_delay)
 796 {
 797         int count = 0;
 798         unsigned char checksum = 0, buf[400];
 799         int raw_count = 0;
 800 
 801         tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
 802         tx_buf_raw[raw_count++] = SIXP_SEOF;
 803 
 804         buf[0] = tx_delay;
 805         for (count = 1; count < length; count++)
 806                 buf[count] = tx_buf[count];
 807 
 808         for (count = 0; count < length; count++)
 809                 checksum += buf[count];
 810         buf[length] = (unsigned char) 0xff - checksum;
 811 
 812         for (count = 0; count <= length; count++) {
 813                 if ((count % 3) == 0) {
 814                         tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
 815                         tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
 816                 } else if ((count % 3) == 1) {
 817                         tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
 818                         tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
 819                 } else {
 820                         tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
 821                         tx_buf_raw[raw_count++] = (buf[count] >> 2);
 822                 }
 823         }
 824         if ((length % 3) != 2)
 825                 raw_count++;
 826         tx_buf_raw[raw_count++] = SIXP_SEOF;
 827         return raw_count;
 828 }
 829 
 830 /* decode 4 sixpack-encoded bytes into 3 data bytes */
 831 
 832 static void decode_data(struct sixpack *sp, unsigned char inbyte)
 833 {
 834         unsigned char *buf;
 835 
 836         if (sp->rx_count != 3) {
 837                 sp->raw_buf[sp->rx_count++] = inbyte;
 838 
 839                 return;
 840         }
 841 
 842         buf = sp->raw_buf;
 843         sp->cooked_buf[sp->rx_count_cooked++] =
 844                 buf[0] | ((buf[1] << 2) & 0xc0);
 845         sp->cooked_buf[sp->rx_count_cooked++] =
 846                 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
 847         sp->cooked_buf[sp->rx_count_cooked++] =
 848                 (buf[2] & 0x03) | (inbyte << 2);
 849         sp->rx_count = 0;
 850 }
 851 
 852 /* identify and execute a 6pack priority command byte */
 853 
 854 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
 855 {
 856         int actual;
 857 
 858         if ((cmd & SIXP_PRIO_DATA_MASK) != 0) {     /* idle ? */
 859 
 860         /* RX and DCD flags can only be set in the same prio command,
 861            if the DCD flag has been set without the RX flag in the previous
 862            prio command. If DCD has not been set before, something in the
 863            transmission has gone wrong. In this case, RX and DCD are
 864            cleared in order to prevent the decode_data routine from
 865            reading further data that might be corrupt. */
 866 
 867                 if (((sp->status & SIXP_DCD_MASK) == 0) &&
 868                         ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
 869                                 if (sp->status != 1)
 870                                         printk(KERN_DEBUG "6pack: protocol violation\n");
 871                                 else
 872                                         sp->status = 0;
 873                                 cmd &= ~SIXP_RX_DCD_MASK;
 874                 }
 875                 sp->status = cmd & SIXP_PRIO_DATA_MASK;
 876         } else { /* output watchdog char if idle */
 877                 if ((sp->status2 != 0) && (sp->duplex == 1)) {
 878                         sp->led_state = 0x70;
 879                         sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 880                         sp->tx_enable = 1;
 881                         actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
 882                         sp->xleft -= actual;
 883                         sp->xhead += actual;
 884                         sp->led_state = 0x60;
 885                         sp->status2 = 0;
 886 
 887                 }
 888         }
 889 
 890         /* needed to trigger the TNC watchdog */
 891         sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 892 
 893         /* if the state byte has been received, the TNC is present,
 894            so the resync timer can be reset. */
 895 
 896         if (sp->tnc_state == TNC_IN_SYNC)
 897                 mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
 898 
 899         sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
 900 }
 901 
 902 /* identify and execute a standard 6pack command byte */
 903 
 904 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
 905 {
 906         unsigned char checksum = 0, rest = 0;
 907         short i;
 908 
 909         switch (cmd & SIXP_CMD_MASK) {     /* normal command */
 910         case SIXP_SEOF:
 911                 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
 912                         if ((sp->status & SIXP_RX_DCD_MASK) ==
 913                                 SIXP_RX_DCD_MASK) {
 914                                 sp->led_state = 0x68;
 915                                 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 916                         }
 917                 } else {
 918                         sp->led_state = 0x60;
 919                         /* fill trailing bytes with zeroes */
 920                         sp->tty->ops->write(sp->tty, &sp->led_state, 1);
 921                         rest = sp->rx_count;
 922                         if (rest != 0)
 923                                  for (i = rest; i <= 3; i++)
 924                                         decode_data(sp, 0);
 925                         if (rest == 2)
 926                                 sp->rx_count_cooked -= 2;
 927                         else if (rest == 3)
 928                                 sp->rx_count_cooked -= 1;
 929                         for (i = 0; i < sp->rx_count_cooked; i++)
 930                                 checksum += sp->cooked_buf[i];
 931                         if (checksum != SIXP_CHKSUM) {
 932                                 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
 933                         } else {
 934                                 sp->rcount = sp->rx_count_cooked-2;
 935                                 sp_bump(sp, 0);
 936                         }
 937                         sp->rx_count_cooked = 0;
 938                 }
 939                 break;
 940         case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
 941                 break;
 942         case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
 943                 break;
 944         case SIXP_RX_BUF_OVL:
 945                 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
 946         }
 947 }
 948 
 949 /* decode a 6pack packet */
 950 
 951 static void
 952 sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
 953 {
 954         unsigned char inbyte;
 955         int count1;
 956 
 957         for (count1 = 0; count1 < count; count1++) {
 958                 inbyte = pre_rbuff[count1];
 959                 if (inbyte == SIXP_FOUND_TNC) {
 960                         tnc_set_sync_state(sp, TNC_IN_SYNC);
 961                         del_timer(&sp->resync_t);
 962                 }
 963                 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
 964                         decode_prio_command(sp, inbyte);
 965                 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
 966                         decode_std_command(sp, inbyte);
 967                 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
 968                         decode_data(sp, inbyte);
 969         }
 970 }
 971 
 972 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
 973 MODULE_DESCRIPTION("6pack driver for AX.25");
 974 MODULE_LICENSE("GPL");
 975 MODULE_ALIAS_LDISC(N_6PACK);
 976 
 977 module_init(sixpack_init_driver);
 978 module_exit(sixpack_exit_driver);
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/net/hamradio/6pack.c

DEFINITIONS
