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@iehk.rwth-aachen.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 <asm/system.h> 17 #include <asm/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 <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 <asm/atomic.h> 38 39 #define SIXPACK_VERSION "Revision: 0.3.0" 40 41 /* sixpack priority commands */ 42 #define SIXP_SEOF 0x40 /* start and end of a 6pack frame */ 43 #define SIXP_TX_URUN 0x48 /* transmit overrun */ 44 #define SIXP_RX_ORUN 0x50 /* receive overrun */ 45 #define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */ 46 47 #define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */ 48 49 /* masks to get certain bits out of the status bytes sent by the TNC */ 50 51 #define SIXP_CMD_MASK 0xC0 52 #define SIXP_CHN_MASK 0x07 53 #define SIXP_PRIO_CMD_MASK 0x80 54 #define SIXP_STD_CMD_MASK 0x40 55 #define SIXP_PRIO_DATA_MASK 0x38 56 #define SIXP_TX_MASK 0x20 57 #define SIXP_RX_MASK 0x10 58 #define SIXP_RX_DCD_MASK 0x18 59 #define SIXP_LEDS_ON 0x78 60 #define SIXP_LEDS_OFF 0x60 61 #define SIXP_CON 0x08 62 #define SIXP_STA 0x10 63 64 #define SIXP_FOUND_TNC 0xe9 65 #define SIXP_CON_ON 0x68 66 #define SIXP_DCD_MASK 0x08 67 #define SIXP_DAMA_OFF 0 68 69 /* default level 2 parameters */ 70 #define SIXP_TXDELAY (HZ/4) /* in 1 s */ 71 #define SIXP_PERSIST 50 /* in 256ths */ 72 #define SIXP_SLOTTIME (HZ/10) /* in 1 s */ 73 #define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */ 74 #define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */ 75 76 /* 6pack configuration. */ 77 #define SIXP_NRUNIT 31 /* MAX number of 6pack channels */ 78 #define SIXP_MTU 256 /* Default MTU */ 79 80 enum sixpack_flags { 81 SIXPF_ERROR, /* Parity, etc. error */ 82 }; 83 84 struct sixpack { 85 /* Various fields. */ 86 struct tty_struct *tty; /* ptr to TTY structure */ 87 struct net_device *dev; /* easy for intr handling */ 88 89 /* These are pointers to the malloc()ed frame buffers. */ 90 unsigned char *rbuff; /* receiver buffer */ 91 int rcount; /* received chars counter */ 92 unsigned char *xbuff; /* transmitter buffer */ 93 unsigned char *xhead; /* next byte to XMIT */ 94 int xleft; /* bytes left in XMIT queue */ 95 96 unsigned char raw_buf[4]; 97 unsigned char cooked_buf[400]; 98 99 unsigned int rx_count; 100 unsigned int rx_count_cooked; 101 102 int mtu; /* Our mtu (to spot changes!) */ 103 int buffsize; /* Max buffers sizes */ 104 105 unsigned long flags; /* Flag values/ mode etc */ 106 unsigned char mode; /* 6pack mode */ 107 108 /* 6pack stuff */ 109 unsigned char tx_delay; 110 unsigned char persistence; 111 unsigned char slottime; 112 unsigned char duplex; 113 unsigned char led_state; 114 unsigned char status; 115 unsigned char status1; 116 unsigned char status2; 117 unsigned char tx_enable; 118 unsigned char tnc_state; 119 120 struct timer_list tx_t; 121 struct timer_list resync_t; 122 atomic_t refcnt; 123 struct semaphore dead_sem; 124 spinlock_t lock; 125 }; 126 127 #define AX25_6PACK_HEADER_LEN 0 128 129 static void sixpack_decode(struct sixpack *, unsigned char[], int); 130 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char); 131 132 /* 133 * Perform the persistence/slottime algorithm for CSMA access. If the 134 * persistence check was successful, write the data to the serial driver. 135 * Note that in case of DAMA operation, the data is not sent here. 136 */ 137 138 static void sp_xmit_on_air(unsigned long channel) 139 { 140 struct sixpack *sp = (struct sixpack *) channel; 141 int actual, when = sp->slottime; 142 static unsigned char random; 143 144 random = random * 17 + 41; 145 146 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) { 147 sp->led_state = 0x70; 148 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 149 sp->tx_enable = 1; 150 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2); 151 sp->xleft -= actual; 152 sp->xhead += actual; 153 sp->led_state = 0x60; 154 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 155 sp->status2 = 0; 156 } else 157 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100); 158 } 159 160 /* ----> 6pack timer interrupt handler and friends. <---- */ 161 162 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */ 163 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len) 164 { 165 unsigned char *msg, *p = icp; 166 int actual, count; 167 168 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ 169 msg = "oversized transmit packet!"; 170 goto out_drop; 171 } 172 173 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ 174 msg = "oversized transmit packet!"; 175 goto out_drop; 176 } 177 178 if (p[0] > 5) { 179 msg = "invalid KISS command"; 180 goto out_drop; 181 } 182 183 if ((p[0] != 0) && (len > 2)) { 184 msg = "KISS control packet too long"; 185 goto out_drop; 186 } 187 188 if ((p[0] == 0) && (len < 15)) { 189 msg = "bad AX.25 packet to transmit"; 190 goto out_drop; 191 } 192 193 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay); 194 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); 195 196 switch (p[0]) { 197 case 1: sp->tx_delay = p[1]; 198 return; 199 case 2: sp->persistence = p[1]; 200 return; 201 case 3: sp->slottime = p[1]; 202 return; 203 case 4: /* ignored */ 204 return; 205 case 5: sp->duplex = p[1]; 206 return; 207 } 208 209 if (p[0] != 0) 210 return; 211 212 /* 213 * In case of fullduplex or DAMA operation, we don't take care about the 214 * state of the DCD or of any timers, as the determination of the 215 * correct time to send is the job of the AX.25 layer. We send 216 * immediately after data has arrived. 217 */ 218 if (sp->duplex == 1) { 219 sp->led_state = 0x70; 220 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 221 sp->tx_enable = 1; 222 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count); 223 sp->xleft = count - actual; 224 sp->xhead = sp->xbuff + actual; 225 sp->led_state = 0x60; 226 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 227 } else { 228 sp->xleft = count; 229 sp->xhead = sp->xbuff; 230 sp->status2 = count; 231 sp_xmit_on_air((unsigned long)sp); 232 } 233 234 return; 235 236 out_drop: 237 sp->dev->stats.tx_dropped++; 238 netif_start_queue(sp->dev); 239 if (net_ratelimit()) 240 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg); 241 } 242 243 /* Encapsulate an IP datagram and kick it into a TTY queue. */ 244 245 static int sp_xmit(struct sk_buff *skb, struct net_device *dev) 246 { 247 struct sixpack *sp = netdev_priv(dev); 248 249 spin_lock_bh(&sp->lock); 250 /* We were not busy, so we are now... :-) */ 251 netif_stop_queue(dev); 252 dev->stats.tx_bytes += skb->len; 253 sp_encaps(sp, skb->data, skb->len); 254 spin_unlock_bh(&sp->lock); 255 256 dev_kfree_skb(skb); 257 258 return 0; 259 } 260 261 static int sp_open_dev(struct net_device *dev) 262 { 263 struct sixpack *sp = netdev_priv(dev); 264 265 if (sp->tty == NULL) 266 return -ENODEV; 267 return 0; 268 } 269 270 /* Close the low-level part of the 6pack channel. */ 271 static int sp_close(struct net_device *dev) 272 { 273 struct sixpack *sp = netdev_priv(dev); 274 275 spin_lock_bh(&sp->lock); 276 if (sp->tty) { 277 /* TTY discipline is running. */ 278 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); 279 } 280 netif_stop_queue(dev); 281 spin_unlock_bh(&sp->lock); 282 283 return 0; 284 } 285 286 /* Return the frame type ID */ 287 static int sp_header(struct sk_buff *skb, struct net_device *dev, 288 unsigned short type, const void *daddr, 289 const void *saddr, unsigned len) 290 { 291 #ifdef CONFIG_INET 292 if (type != ETH_P_AX25) 293 return ax25_hard_header(skb, dev, type, daddr, saddr, len); 294 #endif 295 return 0; 296 } 297 298 static int sp_set_mac_address(struct net_device *dev, void *addr) 299 { 300 struct sockaddr_ax25 *sa = addr; 301 302 netif_tx_lock_bh(dev); 303 netif_addr_lock(dev); 304 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN); 305 netif_addr_unlock(dev); 306 netif_tx_unlock_bh(dev); 307 308 return 0; 309 } 310 311 static int sp_rebuild_header(struct sk_buff *skb) 312 { 313 #ifdef CONFIG_INET 314 return ax25_rebuild_header(skb); 315 #else 316 return 0; 317 #endif 318 } 319 320 static const struct header_ops sp_header_ops = { 321 .create = sp_header, 322 .rebuild = sp_rebuild_header, 323 }; 324 325 static void sp_setup(struct net_device *dev) 326 { 327 /* Finish setting up the DEVICE info. */ 328 dev->mtu = SIXP_MTU; 329 dev->hard_start_xmit = sp_xmit; 330 dev->open = sp_open_dev; 331 dev->destructor = free_netdev; 332 dev->stop = sp_close; 333 334 dev->set_mac_address = sp_set_mac_address; 335 dev->hard_header_len = AX25_MAX_HEADER_LEN; 336 dev->header_ops = &sp_header_ops; 337 338 dev->addr_len = AX25_ADDR_LEN; 339 dev->type = ARPHRD_AX25; 340 dev->tx_queue_len = 10; 341 dev->tx_timeout = NULL; 342 343 /* Only activated in AX.25 mode */ 344 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 345 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); 346 347 dev->flags = 0; 348 } 349 350 /* Send one completely decapsulated IP datagram to the IP layer. */ 351 352 /* 353 * This is the routine that sends the received data to the kernel AX.25. 354 * 'cmd' is the KISS command. For AX.25 data, it is zero. 355 */ 356 357 static void sp_bump(struct sixpack *sp, char cmd) 358 { 359 struct sk_buff *skb; 360 int count; 361 unsigned char *ptr; 362 363 count = sp->rcount + 1; 364 365 sp->dev->stats.rx_bytes += count; 366 367 if ((skb = dev_alloc_skb(count)) == NULL) 368 goto out_mem; 369 370 ptr = skb_put(skb, count); 371 *ptr++ = cmd; /* KISS command */ 372 373 memcpy(ptr, sp->cooked_buf + 1, count); 374 skb->protocol = ax25_type_trans(skb, sp->dev); 375 netif_rx(skb); 376 sp->dev->last_rx = jiffies; 377 sp->dev->stats.rx_packets++; 378 379 return; 380 381 out_mem: 382 sp->dev->stats.rx_dropped++; 383 } 384 385 386 /* ----------------------------------------------------------------------- */ 387 388 /* 389 * We have a potential race on dereferencing tty->disc_data, because the tty 390 * layer provides no locking at all - thus one cpu could be running 391 * sixpack_receive_buf while another calls sixpack_close, which zeroes 392 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The 393 * best way to fix this is to use a rwlock in the tty struct, but for now we 394 * use a single global rwlock for all ttys in ppp line discipline. 395 */ 396 static DEFINE_RWLOCK(disc_data_lock); 397 398 static struct sixpack *sp_get(struct tty_struct *tty) 399 { 400 struct sixpack *sp; 401 402 read_lock(&disc_data_lock); 403 sp = tty->disc_data; 404 if (sp) 405 atomic_inc(&sp->refcnt); 406 read_unlock(&disc_data_lock); 407 408 return sp; 409 } 410 411 static void sp_put(struct sixpack *sp) 412 { 413 if (atomic_dec_and_test(&sp->refcnt)) 414 up(&sp->dead_sem); 415 } 416 417 /* 418 * Called by the TTY driver when there's room for more data. If we have 419 * more packets to send, we send them here. 420 */ 421 static void sixpack_write_wakeup(struct tty_struct *tty) 422 { 423 struct sixpack *sp = sp_get(tty); 424 int actual; 425 426 if (!sp) 427 return; 428 if (sp->xleft <= 0) { 429 /* Now serial buffer is almost free & we can start 430 * transmission of another packet */ 431 sp->dev->stats.tx_packets++; 432 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 433 sp->tx_enable = 0; 434 netif_wake_queue(sp->dev); 435 goto out; 436 } 437 438 if (sp->tx_enable) { 439 actual = tty->ops->write(tty, sp->xhead, sp->xleft); 440 sp->xleft -= actual; 441 sp->xhead += actual; 442 } 443 444 out: 445 sp_put(sp); 446 } 447 448 /* ----------------------------------------------------------------------- */ 449 450 /* 451 * Handle the 'receiver data ready' interrupt. 452 * This function is called by the 'tty_io' module in the kernel when 453 * a block of 6pack data has been received, which can now be decapsulated 454 * and sent on to some IP layer for further processing. 455 */ 456 static void sixpack_receive_buf(struct tty_struct *tty, 457 const unsigned char *cp, char *fp, int count) 458 { 459 struct sixpack *sp; 460 unsigned char buf[512]; 461 int count1; 462 463 if (!count) 464 return; 465 466 sp = sp_get(tty); 467 if (!sp) 468 return; 469 470 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf)); 471 472 /* Read the characters out of the buffer */ 473 474 count1 = count; 475 while (count) { 476 count--; 477 if (fp && *fp++) { 478 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags)) 479 sp->dev->stats.rx_errors++; 480 continue; 481 } 482 } 483 sixpack_decode(sp, buf, count1); 484 485 sp_put(sp); 486 tty_unthrottle(tty); 487 } 488 489 /* 490 * Try to resync the TNC. Called by the resync timer defined in 491 * decode_prio_command 492 */ 493 494 #define TNC_UNINITIALIZED 0 495 #define TNC_UNSYNC_STARTUP 1 496 #define TNC_UNSYNCED 2 497 #define TNC_IN_SYNC 3 498 499 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) 500 { 501 char *msg; 502 503 switch (new_tnc_state) { 504 default: /* gcc oh piece-o-crap ... */ 505 case TNC_UNSYNC_STARTUP: 506 msg = "Synchronizing with TNC"; 507 break; 508 case TNC_UNSYNCED: 509 msg = "Lost synchronization with TNC\n"; 510 break; 511 case TNC_IN_SYNC: 512 msg = "Found TNC"; 513 break; 514 } 515 516 sp->tnc_state = new_tnc_state; 517 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg); 518 } 519 520 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) 521 { 522 int old_tnc_state = sp->tnc_state; 523 524 if (old_tnc_state != new_tnc_state) 525 __tnc_set_sync_state(sp, new_tnc_state); 526 } 527 528 static void resync_tnc(unsigned long channel) 529 { 530 struct sixpack *sp = (struct sixpack *) channel; 531 static char resync_cmd = 0xe8; 532 533 /* clear any data that might have been received */ 534 535 sp->rx_count = 0; 536 sp->rx_count_cooked = 0; 537 538 /* reset state machine */ 539 540 sp->status = 1; 541 sp->status1 = 1; 542 sp->status2 = 0; 543 544 /* resync the TNC */ 545 546 sp->led_state = 0x60; 547 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 548 sp->tty->ops->write(sp->tty, &resync_cmd, 1); 549 550 551 /* Start resync timer again -- the TNC might be still absent */ 552 553 del_timer(&sp->resync_t); 554 sp->resync_t.data = (unsigned long) sp; 555 sp->resync_t.function = resync_tnc; 556 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT; 557 add_timer(&sp->resync_t); 558 } 559 560 static inline int tnc_init(struct sixpack *sp) 561 { 562 unsigned char inbyte = 0xe8; 563 564 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP); 565 566 sp->tty->ops->write(sp->tty, &inbyte, 1); 567 568 del_timer(&sp->resync_t); 569 sp->resync_t.data = (unsigned long) sp; 570 sp->resync_t.function = resync_tnc; 571 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT; 572 add_timer(&sp->resync_t); 573 574 return 0; 575 } 576 577 /* 578 * Open the high-level part of the 6pack channel. 579 * This function is called by the TTY module when the 580 * 6pack line discipline is called for. Because we are 581 * sure the tty line exists, we only have to link it to 582 * a free 6pcack channel... 583 */ 584 static int sixpack_open(struct tty_struct *tty) 585 { 586 char *rbuff = NULL, *xbuff = NULL; 587 struct net_device *dev; 588 struct sixpack *sp; 589 unsigned long len; 590 int err = 0; 591 592 if (!capable(CAP_NET_ADMIN)) 593 return -EPERM; 594 if (tty->ops->write == NULL) 595 return -EOPNOTSUPP; 596 597 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup); 598 if (!dev) { 599 err = -ENOMEM; 600 goto out; 601 } 602 603 sp = netdev_priv(dev); 604 sp->dev = dev; 605 606 spin_lock_init(&sp->lock); 607 atomic_set(&sp->refcnt, 1); 608 init_MUTEX_LOCKED(&sp->dead_sem); 609 610 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */ 611 612 len = dev->mtu * 2; 613 614 rbuff = kmalloc(len + 4, GFP_KERNEL); 615 xbuff = kmalloc(len + 4, GFP_KERNEL); 616 617 if (rbuff == NULL || xbuff == NULL) { 618 err = -ENOBUFS; 619 goto out_free; 620 } 621 622 spin_lock_bh(&sp->lock); 623 624 sp->tty = tty; 625 626 sp->rbuff = rbuff; 627 sp->xbuff = xbuff; 628 629 sp->mtu = AX25_MTU + 73; 630 sp->buffsize = len; 631 sp->rcount = 0; 632 sp->rx_count = 0; 633 sp->rx_count_cooked = 0; 634 sp->xleft = 0; 635 636 sp->flags = 0; /* Clear ESCAPE & ERROR flags */ 637 638 sp->duplex = 0; 639 sp->tx_delay = SIXP_TXDELAY; 640 sp->persistence = SIXP_PERSIST; 641 sp->slottime = SIXP_SLOTTIME; 642 sp->led_state = 0x60; 643 sp->status = 1; 644 sp->status1 = 1; 645 sp->status2 = 0; 646 sp->tx_enable = 0; 647 648 netif_start_queue(dev); 649 650 init_timer(&sp->tx_t); 651 sp->tx_t.function = sp_xmit_on_air; 652 sp->tx_t.data = (unsigned long) sp; 653 654 init_timer(&sp->resync_t); 655 656 spin_unlock_bh(&sp->lock); 657 658 /* Done. We have linked the TTY line to a channel. */ 659 tty->disc_data = sp; 660 tty->receive_room = 65536; 661 662 /* Now we're ready to register. */ 663 if (register_netdev(dev)) 664 goto out_free; 665 666 tnc_init(sp); 667 668 return 0; 669 670 out_free: 671 kfree(xbuff); 672 kfree(rbuff); 673 674 if (dev) 675 free_netdev(dev); 676 677 out: 678 return err; 679 } 680 681 682 /* 683 * Close down a 6pack channel. 684 * This means flushing out any pending queues, and then restoring the 685 * TTY line discipline to what it was before it got hooked to 6pack 686 * (which usually is TTY again). 687 */ 688 static void sixpack_close(struct tty_struct *tty) 689 { 690 struct sixpack *sp; 691 692 write_lock(&disc_data_lock); 693 sp = tty->disc_data; 694 tty->disc_data = NULL; 695 write_unlock(&disc_data_lock); 696 if (!sp) 697 return; 698 699 /* 700 * We have now ensured that nobody can start using ap from now on, but 701 * we have to wait for all existing users to finish. 702 */ 703 if (!atomic_dec_and_test(&sp->refcnt)) 704 down(&sp->dead_sem); 705 706 unregister_netdev(sp->dev); 707 708 del_timer(&sp->tx_t); 709 del_timer(&sp->resync_t); 710 711 /* Free all 6pack frame buffers. */ 712 kfree(sp->rbuff); 713 kfree(sp->xbuff); 714 } 715 716 /* Perform I/O control on an active 6pack channel. */ 717 static int sixpack_ioctl(struct tty_struct *tty, struct file *file, 718 unsigned int cmd, unsigned long arg) 719 { 720 struct sixpack *sp = sp_get(tty); 721 struct net_device *dev = sp->dev; 722 unsigned int tmp, err; 723 724 if (!sp) 725 return -ENXIO; 726 727 switch(cmd) { 728 case SIOCGIFNAME: 729 err = copy_to_user((void __user *) arg, dev->name, 730 strlen(dev->name) + 1) ? -EFAULT : 0; 731 break; 732 733 case SIOCGIFENCAP: 734 err = put_user(0, (int __user *) arg); 735 break; 736 737 case SIOCSIFENCAP: 738 if (get_user(tmp, (int __user *) arg)) { 739 err = -EFAULT; 740 break; 741 } 742 743 sp->mode = tmp; 744 dev->addr_len = AX25_ADDR_LEN; 745 dev->hard_header_len = AX25_KISS_HEADER_LEN + 746 AX25_MAX_HEADER_LEN + 3; 747 dev->type = ARPHRD_AX25; 748 749 err = 0; 750 break; 751 752 case SIOCSIFHWADDR: { 753 char addr[AX25_ADDR_LEN]; 754 755 if (copy_from_user(&addr, 756 (void __user *) arg, AX25_ADDR_LEN)) { 757 err = -EFAULT; 758 break; 759 } 760 761 netif_tx_lock_bh(dev); 762 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN); 763 netif_tx_unlock_bh(dev); 764 765 err = 0; 766 break; 767 } 768 769 default: 770 err = tty_mode_ioctl(tty, file, cmd, arg); 771 } 772 773 sp_put(sp); 774 775 return err; 776 } 777 778 static 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 .receive_buf = sixpack_receive_buf, 786 .write_wakeup = sixpack_write_wakeup, 787 }; 788 789 /* Initialize 6pack control device -- register 6pack line discipline */ 790 791 static char msg_banner[] __initdata = KERN_INFO \ 792 "AX.25: 6pack driver, " SIXPACK_VERSION "\n"; 793 static char msg_regfail[] __initdata = KERN_ERR \ 794 "6pack: can't register line discipline (err = %d)\n"; 795 796 static int __init sixpack_init_driver(void) 797 { 798 int status; 799 800 printk(msg_banner); 801 802 /* Register the provided line protocol discipline */ 803 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0) 804 printk(msg_regfail, status); 805 806 return status; 807 } 808 809 static const char msg_unregfail[] __exitdata = KERN_ERR \ 810 "6pack: can't unregister line discipline (err = %d)\n"; 811 812 static void __exit sixpack_exit_driver(void) 813 { 814 int ret; 815 816 if ((ret = tty_unregister_ldisc(N_6PACK))) 817 printk(msg_unregfail, ret); 818 } 819 820 /* encode an AX.25 packet into 6pack */ 821 822 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw, 823 int length, unsigned char tx_delay) 824 { 825 int count = 0; 826 unsigned char checksum = 0, buf[400]; 827 int raw_count = 0; 828 829 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK; 830 tx_buf_raw[raw_count++] = SIXP_SEOF; 831 832 buf[0] = tx_delay; 833 for (count = 1; count < length; count++) 834 buf[count] = tx_buf[count]; 835 836 for (count = 0; count < length; count++) 837 checksum += buf[count]; 838 buf[length] = (unsigned char) 0xff - checksum; 839 840 for (count = 0; count <= length; count++) { 841 if ((count % 3) == 0) { 842 tx_buf_raw[raw_count++] = (buf[count] & 0x3f); 843 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30); 844 } else if ((count % 3) == 1) { 845 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f); 846 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c); 847 } else { 848 tx_buf_raw[raw_count++] |= (buf[count] & 0x03); 849 tx_buf_raw[raw_count++] = (buf[count] >> 2); 850 } 851 } 852 if ((length % 3) != 2) 853 raw_count++; 854 tx_buf_raw[raw_count++] = SIXP_SEOF; 855 return raw_count; 856 } 857 858 /* decode 4 sixpack-encoded bytes into 3 data bytes */ 859 860 static void decode_data(struct sixpack *sp, unsigned char inbyte) 861 { 862 unsigned char *buf; 863 864 if (sp->rx_count != 3) { 865 sp->raw_buf[sp->rx_count++] = inbyte; 866 867 return; 868 } 869 870 buf = sp->raw_buf; 871 sp->cooked_buf[sp->rx_count_cooked++] = 872 buf[0] | ((buf[1] << 2) & 0xc0); 873 sp->cooked_buf[sp->rx_count_cooked++] = 874 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0); 875 sp->cooked_buf[sp->rx_count_cooked++] = 876 (buf[2] & 0x03) | (inbyte << 2); 877 sp->rx_count = 0; 878 } 879 880 /* identify and execute a 6pack priority command byte */ 881 882 static void decode_prio_command(struct sixpack *sp, unsigned char cmd) 883 { 884 unsigned char channel; 885 int actual; 886 887 channel = cmd & SIXP_CHN_MASK; 888 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */ 889 890 /* RX and DCD flags can only be set in the same prio command, 891 if the DCD flag has been set without the RX flag in the previous 892 prio command. If DCD has not been set before, something in the 893 transmission has gone wrong. In this case, RX and DCD are 894 cleared in order to prevent the decode_data routine from 895 reading further data that might be corrupt. */ 896 897 if (((sp->status & SIXP_DCD_MASK) == 0) && 898 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) { 899 if (sp->status != 1) 900 printk(KERN_DEBUG "6pack: protocol violation\n"); 901 else 902 sp->status = 0; 903 cmd &= ~SIXP_RX_DCD_MASK; 904 } 905 sp->status = cmd & SIXP_PRIO_DATA_MASK; 906 } else { /* output watchdog char if idle */ 907 if ((sp->status2 != 0) && (sp->duplex == 1)) { 908 sp->led_state = 0x70; 909 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 910 sp->tx_enable = 1; 911 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2); 912 sp->xleft -= actual; 913 sp->xhead += actual; 914 sp->led_state = 0x60; 915 sp->status2 = 0; 916 917 } 918 } 919 920 /* needed to trigger the TNC watchdog */ 921 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 922 923 /* if the state byte has been received, the TNC is present, 924 so the resync timer can be reset. */ 925 926 if (sp->tnc_state == TNC_IN_SYNC) { 927 del_timer(&sp->resync_t); 928 sp->resync_t.data = (unsigned long) sp; 929 sp->resync_t.function = resync_tnc; 930 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT; 931 add_timer(&sp->resync_t); 932 } 933 934 sp->status1 = cmd & SIXP_PRIO_DATA_MASK; 935 } 936 937 /* identify and execute a standard 6pack command byte */ 938 939 static void decode_std_command(struct sixpack *sp, unsigned char cmd) 940 { 941 unsigned char checksum = 0, rest = 0, channel; 942 short i; 943 944 channel = cmd & SIXP_CHN_MASK; 945 switch (cmd & SIXP_CMD_MASK) { /* normal command */ 946 case SIXP_SEOF: 947 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) { 948 if ((sp->status & SIXP_RX_DCD_MASK) == 949 SIXP_RX_DCD_MASK) { 950 sp->led_state = 0x68; 951 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 952 } 953 } else { 954 sp->led_state = 0x60; 955 /* fill trailing bytes with zeroes */ 956 sp->tty->ops->write(sp->tty, &sp->led_state, 1); 957 rest = sp->rx_count; 958 if (rest != 0) 959 for (i = rest; i <= 3; i++) 960 decode_data(sp, 0); 961 if (rest == 2) 962 sp->rx_count_cooked -= 2; 963 else if (rest == 3) 964 sp->rx_count_cooked -= 1; 965 for (i = 0; i < sp->rx_count_cooked; i++) 966 checksum += sp->cooked_buf[i]; 967 if (checksum != SIXP_CHKSUM) { 968 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum); 969 } else { 970 sp->rcount = sp->rx_count_cooked-2; 971 sp_bump(sp, 0); 972 } 973 sp->rx_count_cooked = 0; 974 } 975 break; 976 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n"); 977 break; 978 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n"); 979 break; 980 case SIXP_RX_BUF_OVL: 981 printk(KERN_DEBUG "6pack: RX buffer overflow\n"); 982 } 983 } 984 985 /* decode a 6pack packet */ 986 987 static void 988 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count) 989 { 990 unsigned char inbyte; 991 int count1; 992 993 for (count1 = 0; count1 < count; count1++) { 994 inbyte = pre_rbuff[count1]; 995 if (inbyte == SIXP_FOUND_TNC) { 996 tnc_set_sync_state(sp, TNC_IN_SYNC); 997 del_timer(&sp->resync_t); 998 } 999 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0) 1000 decode_prio_command(sp, inbyte); 1001 else if ((inbyte & SIXP_STD_CMD_MASK) != 0) 1002 decode_std_command(sp, inbyte); 1003 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK) 1004 decode_data(sp, inbyte); 1005 } 1006 } 1007 1008 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>"); 1009 MODULE_DESCRIPTION("6pack driver for AX.25"); 1010 MODULE_LICENSE("GPL"); 1011 MODULE_ALIAS_LDISC(N_6PACK); 1012 1013 module_init(sixpack_init_driver); 1014 module_exit(sixpack_exit_driver); 1015