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 <asm/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 /* 6pack interface statistics. */ 103 struct net_device_stats stats; 104 105 int mtu; /* Our mtu (to spot changes!) */ 106 int buffsize; /* Max buffers sizes */ 107 108 unsigned long flags; /* Flag values/ mode etc */ 109 unsigned char mode; /* 6pack mode */ 110 111 /* 6pack stuff */ 112 unsigned char tx_delay; 113 unsigned char persistence; 114 unsigned char slottime; 115 unsigned char duplex; 116 unsigned char led_state; 117 unsigned char status; 118 unsigned char status1; 119 unsigned char status2; 120 unsigned char tx_enable; 121 unsigned char tnc_state; 122 123 struct timer_list tx_t; 124 struct timer_list resync_t; 125 atomic_t refcnt; 126 struct semaphore dead_sem; 127 spinlock_t lock; 128 }; 129 130 #define AX25_6PACK_HEADER_LEN 0 131 132 static void sixpack_decode(struct sixpack *, unsigned char[], int); 133 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char); 134 135 /* 136 * Perform the persistence/slottime algorithm for CSMA access. If the 137 * persistence check was successful, write the data to the serial driver. 138 * Note that in case of DAMA operation, the data is not sent here. 139 */ 140 141 static void sp_xmit_on_air(unsigned long channel) 142 { 143 struct sixpack *sp = (struct sixpack *) channel; 144 int actual, when = sp->slottime; 145 static unsigned char random; 146 147 random = random * 17 + 41; 148 149 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) { 150 sp->led_state = 0x70; 151 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 152 sp->tx_enable = 1; 153 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2); 154 sp->xleft -= actual; 155 sp->xhead += actual; 156 sp->led_state = 0x60; 157 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 158 sp->status2 = 0; 159 } else 160 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100); 161 } 162 163 /* ----> 6pack timer interrupt handler and friends. <---- */ 164 165 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */ 166 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len) 167 { 168 unsigned char *msg, *p = icp; 169 int actual, count; 170 171 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ 172 msg = "oversized transmit packet!"; 173 goto out_drop; 174 } 175 176 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */ 177 msg = "oversized transmit packet!"; 178 goto out_drop; 179 } 180 181 if (p[0] > 5) { 182 msg = "invalid KISS command"; 183 goto out_drop; 184 } 185 186 if ((p[0] != 0) && (len > 2)) { 187 msg = "KISS control packet too long"; 188 goto out_drop; 189 } 190 191 if ((p[0] == 0) && (len < 15)) { 192 msg = "bad AX.25 packet to transmit"; 193 goto out_drop; 194 } 195 196 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay); 197 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); 198 199 switch (p[0]) { 200 case 1: sp->tx_delay = p[1]; 201 return; 202 case 2: sp->persistence = p[1]; 203 return; 204 case 3: sp->slottime = p[1]; 205 return; 206 case 4: /* ignored */ 207 return; 208 case 5: sp->duplex = p[1]; 209 return; 210 } 211 212 if (p[0] != 0) 213 return; 214 215 /* 216 * In case of fullduplex or DAMA operation, we don't take care about the 217 * state of the DCD or of any timers, as the determination of the 218 * correct time to send is the job of the AX.25 layer. We send 219 * immediately after data has arrived. 220 */ 221 if (sp->duplex == 1) { 222 sp->led_state = 0x70; 223 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 224 sp->tx_enable = 1; 225 actual = sp->tty->driver->write(sp->tty, sp->xbuff, count); 226 sp->xleft = count - actual; 227 sp->xhead = sp->xbuff + actual; 228 sp->led_state = 0x60; 229 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 230 } else { 231 sp->xleft = count; 232 sp->xhead = sp->xbuff; 233 sp->status2 = count; 234 sp_xmit_on_air((unsigned long)sp); 235 } 236 237 return; 238 239 out_drop: 240 sp->stats.tx_dropped++; 241 netif_start_queue(sp->dev); 242 if (net_ratelimit()) 243 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg); 244 } 245 246 /* Encapsulate an IP datagram and kick it into a TTY queue. */ 247 248 static int sp_xmit(struct sk_buff *skb, struct net_device *dev) 249 { 250 struct sixpack *sp = netdev_priv(dev); 251 252 spin_lock_bh(&sp->lock); 253 /* We were not busy, so we are now... :-) */ 254 netif_stop_queue(dev); 255 sp->stats.tx_bytes += skb->len; 256 sp_encaps(sp, skb->data, skb->len); 257 spin_unlock_bh(&sp->lock); 258 259 dev_kfree_skb(skb); 260 261 return 0; 262 } 263 264 static int sp_open_dev(struct net_device *dev) 265 { 266 struct sixpack *sp = netdev_priv(dev); 267 268 if (sp->tty == NULL) 269 return -ENODEV; 270 return 0; 271 } 272 273 /* Close the low-level part of the 6pack channel. */ 274 static int sp_close(struct net_device *dev) 275 { 276 struct sixpack *sp = netdev_priv(dev); 277 278 spin_lock_bh(&sp->lock); 279 if (sp->tty) { 280 /* TTY discipline is running. */ 281 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags); 282 } 283 netif_stop_queue(dev); 284 spin_unlock_bh(&sp->lock); 285 286 return 0; 287 } 288 289 /* Return the frame type ID */ 290 static int sp_header(struct sk_buff *skb, struct net_device *dev, 291 unsigned short type, const void *daddr, 292 const void *saddr, unsigned len) 293 { 294 #ifdef CONFIG_INET 295 if (type != ETH_P_AX25) 296 return ax25_hard_header(skb, dev, type, daddr, saddr, len); 297 #endif 298 return 0; 299 } 300 301 static struct net_device_stats *sp_get_stats(struct net_device *dev) 302 { 303 struct sixpack *sp = netdev_priv(dev); 304 return &sp->stats; 305 } 306 307 static int sp_set_mac_address(struct net_device *dev, void *addr) 308 { 309 struct sockaddr_ax25 *sa = addr; 310 311 netif_tx_lock_bh(dev); 312 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN); 313 netif_tx_unlock_bh(dev); 314 315 return 0; 316 } 317 318 static int sp_rebuild_header(struct sk_buff *skb) 319 { 320 #ifdef CONFIG_INET 321 return ax25_rebuild_header(skb); 322 #else 323 return 0; 324 #endif 325 } 326 327 static const struct header_ops sp_header_ops = { 328 .create = sp_header, 329 .rebuild = sp_rebuild_header, 330 }; 331 332 static void sp_setup(struct net_device *dev) 333 { 334 /* Finish setting up the DEVICE info. */ 335 dev->mtu = SIXP_MTU; 336 dev->hard_start_xmit = sp_xmit; 337 dev->open = sp_open_dev; 338 dev->destructor = free_netdev; 339 dev->stop = sp_close; 340 341 dev->get_stats = sp_get_stats; 342 dev->set_mac_address = sp_set_mac_address; 343 dev->hard_header_len = AX25_MAX_HEADER_LEN; 344 dev->header_ops = &sp_header_ops; 345 346 dev->addr_len = AX25_ADDR_LEN; 347 dev->type = ARPHRD_AX25; 348 dev->tx_queue_len = 10; 349 dev->tx_timeout = NULL; 350 351 /* Only activated in AX.25 mode */ 352 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 353 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); 354 355 dev->flags = 0; 356 } 357 358 /* Send one completely decapsulated IP datagram to the IP layer. */ 359 360 /* 361 * This is the routine that sends the received data to the kernel AX.25. 362 * 'cmd' is the KISS command. For AX.25 data, it is zero. 363 */ 364 365 static void sp_bump(struct sixpack *sp, char cmd) 366 { 367 struct sk_buff *skb; 368 int count; 369 unsigned char *ptr; 370 371 count = sp->rcount + 1; 372 373 sp->stats.rx_bytes += count; 374 375 if ((skb = dev_alloc_skb(count)) == NULL) 376 goto out_mem; 377 378 ptr = skb_put(skb, count); 379 *ptr++ = cmd; /* KISS command */ 380 381 memcpy(ptr, sp->cooked_buf + 1, count); 382 skb->protocol = ax25_type_trans(skb, sp->dev); 383 netif_rx(skb); 384 sp->dev->last_rx = jiffies; 385 sp->stats.rx_packets++; 386 387 return; 388 389 out_mem: 390 sp->stats.rx_dropped++; 391 } 392 393 394 /* ----------------------------------------------------------------------- */ 395 396 /* 397 * We have a potential race on dereferencing tty->disc_data, because the tty 398 * layer provides no locking at all - thus one cpu could be running 399 * sixpack_receive_buf while another calls sixpack_close, which zeroes 400 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The 401 * best way to fix this is to use a rwlock in the tty struct, but for now we 402 * use a single global rwlock for all ttys in ppp line discipline. 403 */ 404 static DEFINE_RWLOCK(disc_data_lock); 405 406 static struct sixpack *sp_get(struct tty_struct *tty) 407 { 408 struct sixpack *sp; 409 410 read_lock(&disc_data_lock); 411 sp = tty->disc_data; 412 if (sp) 413 atomic_inc(&sp->refcnt); 414 read_unlock(&disc_data_lock); 415 416 return sp; 417 } 418 419 static void sp_put(struct sixpack *sp) 420 { 421 if (atomic_dec_and_test(&sp->refcnt)) 422 up(&sp->dead_sem); 423 } 424 425 /* 426 * Called by the TTY driver when there's room for more data. If we have 427 * more packets to send, we send them here. 428 */ 429 static void sixpack_write_wakeup(struct tty_struct *tty) 430 { 431 struct sixpack *sp = sp_get(tty); 432 int actual; 433 434 if (!sp) 435 return; 436 if (sp->xleft <= 0) { 437 /* Now serial buffer is almost free & we can start 438 * transmission of another packet */ 439 sp->stats.tx_packets++; 440 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 441 sp->tx_enable = 0; 442 netif_wake_queue(sp->dev); 443 goto out; 444 } 445 446 if (sp->tx_enable) { 447 actual = tty->driver->write(tty, sp->xhead, sp->xleft); 448 sp->xleft -= actual; 449 sp->xhead += actual; 450 } 451 452 out: 453 sp_put(sp); 454 } 455 456 /* ----------------------------------------------------------------------- */ 457 458 /* 459 * Handle the 'receiver data ready' interrupt. 460 * This function is called by the 'tty_io' module in the kernel when 461 * a block of 6pack data has been received, which can now be decapsulated 462 * and sent on to some IP layer for further processing. 463 */ 464 static void sixpack_receive_buf(struct tty_struct *tty, 465 const unsigned char *cp, char *fp, int count) 466 { 467 struct sixpack *sp; 468 unsigned char buf[512]; 469 int count1; 470 471 if (!count) 472 return; 473 474 sp = sp_get(tty); 475 if (!sp) 476 return; 477 478 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf)); 479 480 /* Read the characters out of the buffer */ 481 482 count1 = count; 483 while (count) { 484 count--; 485 if (fp && *fp++) { 486 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags)) 487 sp->stats.rx_errors++; 488 continue; 489 } 490 } 491 sixpack_decode(sp, buf, count1); 492 493 sp_put(sp); 494 if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) 495 && tty->driver->unthrottle) 496 tty->driver->unthrottle(tty); 497 } 498 499 /* 500 * Try to resync the TNC. Called by the resync timer defined in 501 * decode_prio_command 502 */ 503 504 #define TNC_UNINITIALIZED 0 505 #define TNC_UNSYNC_STARTUP 1 506 #define TNC_UNSYNCED 2 507 #define TNC_IN_SYNC 3 508 509 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) 510 { 511 char *msg; 512 513 switch (new_tnc_state) { 514 default: /* gcc oh piece-o-crap ... */ 515 case TNC_UNSYNC_STARTUP: 516 msg = "Synchronizing with TNC"; 517 break; 518 case TNC_UNSYNCED: 519 msg = "Lost synchronization with TNC\n"; 520 break; 521 case TNC_IN_SYNC: 522 msg = "Found TNC"; 523 break; 524 } 525 526 sp->tnc_state = new_tnc_state; 527 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg); 528 } 529 530 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state) 531 { 532 int old_tnc_state = sp->tnc_state; 533 534 if (old_tnc_state != new_tnc_state) 535 __tnc_set_sync_state(sp, new_tnc_state); 536 } 537 538 static void resync_tnc(unsigned long channel) 539 { 540 struct sixpack *sp = (struct sixpack *) channel; 541 static char resync_cmd = 0xe8; 542 543 /* clear any data that might have been received */ 544 545 sp->rx_count = 0; 546 sp->rx_count_cooked = 0; 547 548 /* reset state machine */ 549 550 sp->status = 1; 551 sp->status1 = 1; 552 sp->status2 = 0; 553 554 /* resync the TNC */ 555 556 sp->led_state = 0x60; 557 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 558 sp->tty->driver->write(sp->tty, &resync_cmd, 1); 559 560 561 /* Start resync timer again -- the TNC might be still absent */ 562 563 del_timer(&sp->resync_t); 564 sp->resync_t.data = (unsigned long) sp; 565 sp->resync_t.function = resync_tnc; 566 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT; 567 add_timer(&sp->resync_t); 568 } 569 570 static inline int tnc_init(struct sixpack *sp) 571 { 572 unsigned char inbyte = 0xe8; 573 574 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP); 575 576 sp->tty->driver->write(sp->tty, &inbyte, 1); 577 578 del_timer(&sp->resync_t); 579 sp->resync_t.data = (unsigned long) sp; 580 sp->resync_t.function = resync_tnc; 581 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT; 582 add_timer(&sp->resync_t); 583 584 return 0; 585 } 586 587 /* 588 * Open the high-level part of the 6pack channel. 589 * This function is called by the TTY module when the 590 * 6pack line discipline is called for. Because we are 591 * sure the tty line exists, we only have to link it to 592 * a free 6pcack channel... 593 */ 594 static int sixpack_open(struct tty_struct *tty) 595 { 596 char *rbuff = NULL, *xbuff = NULL; 597 struct net_device *dev; 598 struct sixpack *sp; 599 unsigned long len; 600 int err = 0; 601 602 if (!capable(CAP_NET_ADMIN)) 603 return -EPERM; 604 605 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup); 606 if (!dev) { 607 err = -ENOMEM; 608 goto out; 609 } 610 611 sp = netdev_priv(dev); 612 sp->dev = dev; 613 614 spin_lock_init(&sp->lock); 615 atomic_set(&sp->refcnt, 1); 616 init_MUTEX_LOCKED(&sp->dead_sem); 617 618 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */ 619 620 len = dev->mtu * 2; 621 622 rbuff = kmalloc(len + 4, GFP_KERNEL); 623 xbuff = kmalloc(len + 4, GFP_KERNEL); 624 625 if (rbuff == NULL || xbuff == NULL) { 626 err = -ENOBUFS; 627 goto out_free; 628 } 629 630 spin_lock_bh(&sp->lock); 631 632 sp->tty = tty; 633 634 sp->rbuff = rbuff; 635 sp->xbuff = xbuff; 636 637 sp->mtu = AX25_MTU + 73; 638 sp->buffsize = len; 639 sp->rcount = 0; 640 sp->rx_count = 0; 641 sp->rx_count_cooked = 0; 642 sp->xleft = 0; 643 644 sp->flags = 0; /* Clear ESCAPE & ERROR flags */ 645 646 sp->duplex = 0; 647 sp->tx_delay = SIXP_TXDELAY; 648 sp->persistence = SIXP_PERSIST; 649 sp->slottime = SIXP_SLOTTIME; 650 sp->led_state = 0x60; 651 sp->status = 1; 652 sp->status1 = 1; 653 sp->status2 = 0; 654 sp->tx_enable = 0; 655 656 netif_start_queue(dev); 657 658 init_timer(&sp->tx_t); 659 sp->tx_t.function = sp_xmit_on_air; 660 sp->tx_t.data = (unsigned long) sp; 661 662 init_timer(&sp->resync_t); 663 664 spin_unlock_bh(&sp->lock); 665 666 /* Done. We have linked the TTY line to a channel. */ 667 tty->disc_data = sp; 668 tty->receive_room = 65536; 669 670 /* Now we're ready to register. */ 671 if (register_netdev(dev)) 672 goto out_free; 673 674 tnc_init(sp); 675 676 return 0; 677 678 out_free: 679 kfree(xbuff); 680 kfree(rbuff); 681 682 if (dev) 683 free_netdev(dev); 684 685 out: 686 return err; 687 } 688 689 690 /* 691 * Close down a 6pack channel. 692 * This means flushing out any pending queues, and then restoring the 693 * TTY line discipline to what it was before it got hooked to 6pack 694 * (which usually is TTY again). 695 */ 696 static void sixpack_close(struct tty_struct *tty) 697 { 698 struct sixpack *sp; 699 700 write_lock(&disc_data_lock); 701 sp = tty->disc_data; 702 tty->disc_data = NULL; 703 write_unlock(&disc_data_lock); 704 if (!sp) 705 return; 706 707 /* 708 * We have now ensured that nobody can start using ap from now on, but 709 * we have to wait for all existing users to finish. 710 */ 711 if (!atomic_dec_and_test(&sp->refcnt)) 712 down(&sp->dead_sem); 713 714 unregister_netdev(sp->dev); 715 716 del_timer(&sp->tx_t); 717 del_timer(&sp->resync_t); 718 719 /* Free all 6pack frame buffers. */ 720 kfree(sp->rbuff); 721 kfree(sp->xbuff); 722 } 723 724 /* Perform I/O control on an active 6pack channel. */ 725 static int sixpack_ioctl(struct tty_struct *tty, struct file *file, 726 unsigned int cmd, unsigned long arg) 727 { 728 struct sixpack *sp = sp_get(tty); 729 struct net_device *dev = sp->dev; 730 unsigned int tmp, err; 731 732 if (!sp) 733 return -ENXIO; 734 735 switch(cmd) { 736 case SIOCGIFNAME: 737 err = copy_to_user((void __user *) arg, dev->name, 738 strlen(dev->name) + 1) ? -EFAULT : 0; 739 break; 740 741 case SIOCGIFENCAP: 742 err = put_user(0, (int __user *) arg); 743 break; 744 745 case SIOCSIFENCAP: 746 if (get_user(tmp, (int __user *) arg)) { 747 err = -EFAULT; 748 break; 749 } 750 751 sp->mode = tmp; 752 dev->addr_len = AX25_ADDR_LEN; 753 dev->hard_header_len = AX25_KISS_HEADER_LEN + 754 AX25_MAX_HEADER_LEN + 3; 755 dev->type = ARPHRD_AX25; 756 757 err = 0; 758 break; 759 760 case SIOCSIFHWADDR: { 761 char addr[AX25_ADDR_LEN]; 762 763 if (copy_from_user(&addr, 764 (void __user *) arg, AX25_ADDR_LEN)) { 765 err = -EFAULT; 766 break; 767 } 768 769 netif_tx_lock_bh(dev); 770 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN); 771 netif_tx_unlock_bh(dev); 772 773 err = 0; 774 break; 775 } 776 777 default: 778 err = tty_mode_ioctl(tty, file, cmd, arg); 779 } 780 781 sp_put(sp); 782 783 return err; 784 } 785 786 static struct tty_ldisc sp_ldisc = { 787 .owner = THIS_MODULE, 788 .magic = TTY_LDISC_MAGIC, 789 .name = "6pack", 790 .open = sixpack_open, 791 .close = sixpack_close, 792 .ioctl = sixpack_ioctl, 793 .receive_buf = sixpack_receive_buf, 794 .write_wakeup = sixpack_write_wakeup, 795 }; 796 797 /* Initialize 6pack control device -- register 6pack line discipline */ 798 799 static char msg_banner[] __initdata = KERN_INFO \ 800 "AX.25: 6pack driver, " SIXPACK_VERSION "\n"; 801 static char msg_regfail[] __initdata = KERN_ERR \ 802 "6pack: can't register line discipline (err = %d)\n"; 803 804 static int __init sixpack_init_driver(void) 805 { 806 int status; 807 808 printk(msg_banner); 809 810 /* Register the provided line protocol discipline */ 811 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0) 812 printk(msg_regfail, status); 813 814 return status; 815 } 816 817 static const char msg_unregfail[] __exitdata = KERN_ERR \ 818 "6pack: can't unregister line discipline (err = %d)\n"; 819 820 static void __exit sixpack_exit_driver(void) 821 { 822 int ret; 823 824 if ((ret = tty_unregister_ldisc(N_6PACK))) 825 printk(msg_unregfail, ret); 826 } 827 828 /* encode an AX.25 packet into 6pack */ 829 830 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw, 831 int length, unsigned char tx_delay) 832 { 833 int count = 0; 834 unsigned char checksum = 0, buf[400]; 835 int raw_count = 0; 836 837 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK; 838 tx_buf_raw[raw_count++] = SIXP_SEOF; 839 840 buf[0] = tx_delay; 841 for (count = 1; count < length; count++) 842 buf[count] = tx_buf[count]; 843 844 for (count = 0; count < length; count++) 845 checksum += buf[count]; 846 buf[length] = (unsigned char) 0xff - checksum; 847 848 for (count = 0; count <= length; count++) { 849 if ((count % 3) == 0) { 850 tx_buf_raw[raw_count++] = (buf[count] & 0x3f); 851 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30); 852 } else if ((count % 3) == 1) { 853 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f); 854 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c); 855 } else { 856 tx_buf_raw[raw_count++] |= (buf[count] & 0x03); 857 tx_buf_raw[raw_count++] = (buf[count] >> 2); 858 } 859 } 860 if ((length % 3) != 2) 861 raw_count++; 862 tx_buf_raw[raw_count++] = SIXP_SEOF; 863 return raw_count; 864 } 865 866 /* decode 4 sixpack-encoded bytes into 3 data bytes */ 867 868 static void decode_data(struct sixpack *sp, unsigned char inbyte) 869 { 870 unsigned char *buf; 871 872 if (sp->rx_count != 3) { 873 sp->raw_buf[sp->rx_count++] = inbyte; 874 875 return; 876 } 877 878 buf = sp->raw_buf; 879 sp->cooked_buf[sp->rx_count_cooked++] = 880 buf[0] | ((buf[1] << 2) & 0xc0); 881 sp->cooked_buf[sp->rx_count_cooked++] = 882 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0); 883 sp->cooked_buf[sp->rx_count_cooked++] = 884 (buf[2] & 0x03) | (inbyte << 2); 885 sp->rx_count = 0; 886 } 887 888 /* identify and execute a 6pack priority command byte */ 889 890 static void decode_prio_command(struct sixpack *sp, unsigned char cmd) 891 { 892 unsigned char channel; 893 int actual; 894 895 channel = cmd & SIXP_CHN_MASK; 896 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */ 897 898 /* RX and DCD flags can only be set in the same prio command, 899 if the DCD flag has been set without the RX flag in the previous 900 prio command. If DCD has not been set before, something in the 901 transmission has gone wrong. In this case, RX and DCD are 902 cleared in order to prevent the decode_data routine from 903 reading further data that might be corrupt. */ 904 905 if (((sp->status & SIXP_DCD_MASK) == 0) && 906 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) { 907 if (sp->status != 1) 908 printk(KERN_DEBUG "6pack: protocol violation\n"); 909 else 910 sp->status = 0; 911 cmd &= ~SIXP_RX_DCD_MASK; 912 } 913 sp->status = cmd & SIXP_PRIO_DATA_MASK; 914 } else { /* output watchdog char if idle */ 915 if ((sp->status2 != 0) && (sp->duplex == 1)) { 916 sp->led_state = 0x70; 917 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 918 sp->tx_enable = 1; 919 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2); 920 sp->xleft -= actual; 921 sp->xhead += actual; 922 sp->led_state = 0x60; 923 sp->status2 = 0; 924 925 } 926 } 927 928 /* needed to trigger the TNC watchdog */ 929 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 930 931 /* if the state byte has been received, the TNC is present, 932 so the resync timer can be reset. */ 933 934 if (sp->tnc_state == TNC_IN_SYNC) { 935 del_timer(&sp->resync_t); 936 sp->resync_t.data = (unsigned long) sp; 937 sp->resync_t.function = resync_tnc; 938 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT; 939 add_timer(&sp->resync_t); 940 } 941 942 sp->status1 = cmd & SIXP_PRIO_DATA_MASK; 943 } 944 945 /* identify and execute a standard 6pack command byte */ 946 947 static void decode_std_command(struct sixpack *sp, unsigned char cmd) 948 { 949 unsigned char checksum = 0, rest = 0, channel; 950 short i; 951 952 channel = cmd & SIXP_CHN_MASK; 953 switch (cmd & SIXP_CMD_MASK) { /* normal command */ 954 case SIXP_SEOF: 955 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) { 956 if ((sp->status & SIXP_RX_DCD_MASK) == 957 SIXP_RX_DCD_MASK) { 958 sp->led_state = 0x68; 959 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 960 } 961 } else { 962 sp->led_state = 0x60; 963 /* fill trailing bytes with zeroes */ 964 sp->tty->driver->write(sp->tty, &sp->led_state, 1); 965 rest = sp->rx_count; 966 if (rest != 0) 967 for (i = rest; i <= 3; i++) 968 decode_data(sp, 0); 969 if (rest == 2) 970 sp->rx_count_cooked -= 2; 971 else if (rest == 3) 972 sp->rx_count_cooked -= 1; 973 for (i = 0; i < sp->rx_count_cooked; i++) 974 checksum += sp->cooked_buf[i]; 975 if (checksum != SIXP_CHKSUM) { 976 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum); 977 } else { 978 sp->rcount = sp->rx_count_cooked-2; 979 sp_bump(sp, 0); 980 } 981 sp->rx_count_cooked = 0; 982 } 983 break; 984 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n"); 985 break; 986 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n"); 987 break; 988 case SIXP_RX_BUF_OVL: 989 printk(KERN_DEBUG "6pack: RX buffer overflow\n"); 990 } 991 } 992 993 /* decode a 6pack packet */ 994 995 static void 996 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count) 997 { 998 unsigned char inbyte; 999 int count1; 1000 1001 for (count1 = 0; count1 < count; count1++) { 1002 inbyte = pre_rbuff[count1]; 1003 if (inbyte == SIXP_FOUND_TNC) { 1004 tnc_set_sync_state(sp, TNC_IN_SYNC); 1005 del_timer(&sp->resync_t); 1006 } 1007 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0) 1008 decode_prio_command(sp, inbyte); 1009 else if ((inbyte & SIXP_STD_CMD_MASK) != 0) 1010 decode_std_command(sp, inbyte); 1011 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK) 1012 decode_data(sp, inbyte); 1013 } 1014 } 1015 1016 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>"); 1017 MODULE_DESCRIPTION("6pack driver for AX.25"); 1018 MODULE_LICENSE("GPL"); 1019 MODULE_ALIAS_LDISC(N_6PACK); 1020 1021 module_init(sixpack_init_driver); 1022 module_exit(sixpack_exit_driver); 1023