961 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * 6pack.c This module implements the 6pack protocol for kernel-based4 * devices like TTY. It interfaces between a raw TTY and the5 * 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 by11 *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/* sixpack priority commands */41#define SIXP_SEOF 0x40 /* start and end of a 6pack frame */42#define SIXP_TX_URUN 0x48 /* transmit overrun */43#define SIXP_RX_ORUN 0x50 /* receive overrun */44#define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */45 46#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */47 48/* masks to get certain bits out of the status bytes sent by the TNC */49 50#define SIXP_CMD_MASK 0xC051#define SIXP_CHN_MASK 0x0752#define SIXP_PRIO_CMD_MASK 0x8053#define SIXP_STD_CMD_MASK 0x4054#define SIXP_PRIO_DATA_MASK 0x3855#define SIXP_TX_MASK 0x2056#define SIXP_RX_MASK 0x1057#define SIXP_RX_DCD_MASK 0x1858#define SIXP_LEDS_ON 0x7859#define SIXP_LEDS_OFF 0x6060#define SIXP_CON 0x0861#define SIXP_STA 0x1062 63#define SIXP_FOUND_TNC 0xe964#define SIXP_CON_ON 0x6865#define SIXP_DCD_MASK 0x0866#define SIXP_DAMA_OFF 067 68/* default level 2 parameters */69#define SIXP_TXDELAY 25 /* 250 ms */70#define SIXP_PERSIST 50 /* in 256ths */71#define SIXP_SLOTTIME 10 /* 100 ms */72#define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */73#define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */74 75/* 6pack configuration. */76#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */77#define SIXP_MTU 256 /* Default MTU */78 79enum sixpack_flags {80 SIXPF_ERROR, /* Parity, etc. error */81};82 83struct sixpack {84 /* Various fields. */85 struct tty_struct *tty; /* ptr to TTY structure */86 struct net_device *dev; /* easy for intr handling */87 88 /* These are pointers to the malloc()ed frame buffers. */89 int rcount; /* received chars counter */90 unsigned char *xbuff; /* transmitter buffer */91 unsigned char *xhead; /* next byte to XMIT */92 int xleft; /* bytes left in XMIT queue */93 94 u8 raw_buf[4];95 u8 cooked_buf[400];96 97 unsigned int rx_count;98 unsigned int rx_count_cooked;99 spinlock_t rxlock;100 101 unsigned long flags; /* Flag values/ mode etc */102 unsigned char mode; /* 6pack mode */103 104 /* 6pack stuff */105 unsigned char tx_delay;106 unsigned char persistence;107 unsigned char slottime;108 unsigned char duplex;109 unsigned char led_state;110 u8 status;111 u8 status1;112 unsigned char status2;113 unsigned char tx_enable;114 unsigned char tnc_state;115 116 struct timer_list tx_t;117 struct timer_list resync_t;118 refcount_t refcnt;119 struct completion dead;120 spinlock_t lock;121};122 123#define AX25_6PACK_HEADER_LEN 0124 125static void sixpack_decode(struct sixpack *, const u8 *, size_t);126static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);127 128/*129 * Perform the persistence/slottime algorithm for CSMA access. If the130 * persistence check was successful, write the data to the serial driver.131 * Note that in case of DAMA operation, the data is not sent here.132 */133 134static void sp_xmit_on_air(struct timer_list *t)135{136 struct sixpack *sp = from_timer(sp, t, tx_t);137 int actual, when = sp->slottime;138 static unsigned char random;139 140 random = random * 17 + 41;141 142 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {143 sp->led_state = 0x70;144 sp->tty->ops->write(sp->tty, &sp->led_state, 1);145 sp->tx_enable = 1;146 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);147 sp->xleft -= actual;148 sp->xhead += actual;149 sp->led_state = 0x60;150 sp->tty->ops->write(sp->tty, &sp->led_state, 1);151 sp->status2 = 0;152 } else153 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);154}155 156/* ----> 6pack timer interrupt handler and friends. <---- */157 158/* Encapsulate one AX.25 frame and stuff into a TTY queue. */159static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)160{161 unsigned char *msg, *p = icp;162 int actual, count;163 164 if (len > AX25_MTU + 73) {165 msg = "oversized transmit packet!";166 goto out_drop;167 }168 169 if (p[0] > 5) {170 msg = "invalid KISS command";171 goto out_drop;172 }173 174 if ((p[0] != 0) && (len > 2)) {175 msg = "KISS control packet too long";176 goto out_drop;177 }178 179 if ((p[0] == 0) && (len < 15)) {180 msg = "bad AX.25 packet to transmit";181 goto out_drop;182 }183 184 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);185 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);186 187 switch (p[0]) {188 case 1: sp->tx_delay = p[1];189 return;190 case 2: sp->persistence = p[1];191 return;192 case 3: sp->slottime = p[1];193 return;194 case 4: /* ignored */195 return;196 case 5: sp->duplex = p[1];197 return;198 }199 200 if (p[0] != 0)201 return;202 203 /*204 * In case of fullduplex or DAMA operation, we don't take care about the205 * state of the DCD or of any timers, as the determination of the206 * correct time to send is the job of the AX.25 layer. We send207 * immediately after data has arrived.208 */209 if (sp->duplex == 1) {210 sp->led_state = 0x70;211 sp->tty->ops->write(sp->tty, &sp->led_state, 1);212 sp->tx_enable = 1;213 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);214 sp->xleft = count - actual;215 sp->xhead = sp->xbuff + actual;216 sp->led_state = 0x60;217 sp->tty->ops->write(sp->tty, &sp->led_state, 1);218 } else {219 sp->xleft = count;220 sp->xhead = sp->xbuff;221 sp->status2 = count;222 sp_xmit_on_air(&sp->tx_t);223 }224 225 return;226 227out_drop:228 sp->dev->stats.tx_dropped++;229 netif_start_queue(sp->dev);230 if (net_ratelimit())231 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);232}233 234/* Encapsulate an IP datagram and kick it into a TTY queue. */235 236static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)237{238 struct sixpack *sp = netdev_priv(dev);239 240 if (skb->protocol == htons(ETH_P_IP))241 return ax25_ip_xmit(skb);242 243 spin_lock_bh(&sp->lock);244 /* We were not busy, so we are now... :-) */245 netif_stop_queue(dev);246 dev->stats.tx_bytes += skb->len;247 sp_encaps(sp, skb->data, skb->len);248 spin_unlock_bh(&sp->lock);249 250 dev_kfree_skb(skb);251 252 return NETDEV_TX_OK;253}254 255static int sp_open_dev(struct net_device *dev)256{257 struct sixpack *sp = netdev_priv(dev);258 259 if (sp->tty == NULL)260 return -ENODEV;261 return 0;262}263 264/* Close the low-level part of the 6pack channel. */265static int sp_close(struct net_device *dev)266{267 struct sixpack *sp = netdev_priv(dev);268 269 spin_lock_bh(&sp->lock);270 if (sp->tty) {271 /* TTY discipline is running. */272 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);273 }274 netif_stop_queue(dev);275 spin_unlock_bh(&sp->lock);276 277 return 0;278}279 280static int sp_set_mac_address(struct net_device *dev, void *addr)281{282 struct sockaddr_ax25 *sa = addr;283 284 netif_tx_lock_bh(dev);285 netif_addr_lock(dev);286 __dev_addr_set(dev, &sa->sax25_call, AX25_ADDR_LEN);287 netif_addr_unlock(dev);288 netif_tx_unlock_bh(dev);289 290 return 0;291}292 293static const struct net_device_ops sp_netdev_ops = {294 .ndo_open = sp_open_dev,295 .ndo_stop = sp_close,296 .ndo_start_xmit = sp_xmit,297 .ndo_set_mac_address = sp_set_mac_address,298};299 300static void sp_setup(struct net_device *dev)301{302 /* Finish setting up the DEVICE info. */303 dev->netdev_ops = &sp_netdev_ops;304 dev->mtu = SIXP_MTU;305 dev->hard_header_len = AX25_MAX_HEADER_LEN;306 dev->header_ops = &ax25_header_ops;307 308 dev->addr_len = AX25_ADDR_LEN;309 dev->type = ARPHRD_AX25;310 dev->tx_queue_len = 10;311 312 /* Only activated in AX.25 mode */313 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);314 dev_addr_set(dev, (u8 *)&ax25_defaddr);315 316 dev->flags = 0;317}318 319/* Send one completely decapsulated IP datagram to the IP layer. */320 321/*322 * This is the routine that sends the received data to the kernel AX.25.323 * 'cmd' is the KISS command. For AX.25 data, it is zero.324 */325 326static void sp_bump(struct sixpack *sp, char cmd)327{328 struct sk_buff *skb;329 int count;330 u8 *ptr;331 332 count = sp->rcount + 1;333 334 sp->dev->stats.rx_bytes += count;335 336 if ((skb = dev_alloc_skb(count + 1)) == NULL)337 goto out_mem;338 339 ptr = skb_put(skb, count + 1);340 *ptr++ = cmd; /* KISS command */341 342 memcpy(ptr, sp->cooked_buf + 1, count);343 skb->protocol = ax25_type_trans(skb, sp->dev);344 netif_rx(skb);345 sp->dev->stats.rx_packets++;346 347 return;348 349out_mem:350 sp->dev->stats.rx_dropped++;351}352 353 354/* ----------------------------------------------------------------------- */355 356/*357 * We have a potential race on dereferencing tty->disc_data, because the tty358 * layer provides no locking at all - thus one cpu could be running359 * sixpack_receive_buf while another calls sixpack_close, which zeroes360 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The361 * best way to fix this is to use a rwlock in the tty struct, but for now we362 * use a single global rwlock for all ttys in ppp line discipline.363 */364static DEFINE_RWLOCK(disc_data_lock);365 366static struct sixpack *sp_get(struct tty_struct *tty)367{368 struct sixpack *sp;369 370 read_lock(&disc_data_lock);371 sp = tty->disc_data;372 if (sp)373 refcount_inc(&sp->refcnt);374 read_unlock(&disc_data_lock);375 376 return sp;377}378 379static void sp_put(struct sixpack *sp)380{381 if (refcount_dec_and_test(&sp->refcnt))382 complete(&sp->dead);383}384 385/*386 * Called by the TTY driver when there's room for more data. If we have387 * more packets to send, we send them here.388 */389static void sixpack_write_wakeup(struct tty_struct *tty)390{391 struct sixpack *sp = sp_get(tty);392 int actual;393 394 if (!sp)395 return;396 if (sp->xleft <= 0) {397 /* Now serial buffer is almost free & we can start398 * transmission of another packet */399 sp->dev->stats.tx_packets++;400 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);401 sp->tx_enable = 0;402 netif_wake_queue(sp->dev);403 goto out;404 }405 406 if (sp->tx_enable) {407 actual = tty->ops->write(tty, sp->xhead, sp->xleft);408 sp->xleft -= actual;409 sp->xhead += actual;410 }411 412out:413 sp_put(sp);414}415 416/* ----------------------------------------------------------------------- */417 418/*419 * Handle the 'receiver data ready' interrupt.420 * This function is called by the tty module in the kernel when421 * a block of 6pack data has been received, which can now be decapsulated422 * and sent on to some IP layer for further processing.423 */424static void sixpack_receive_buf(struct tty_struct *tty, const u8 *cp,425 const u8 *fp, size_t count)426{427 struct sixpack *sp;428 size_t count1;429 430 if (!count)431 return;432 433 sp = sp_get(tty);434 if (!sp)435 return;436 437 /* Read the characters out of the buffer */438 count1 = count;439 while (count) {440 count--;441 if (fp && *fp++) {442 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))443 sp->dev->stats.rx_errors++;444 continue;445 }446 }447 sixpack_decode(sp, cp, count1);448 449 sp_put(sp);450 tty_unthrottle(tty);451}452 453/*454 * Try to resync the TNC. Called by the resync timer defined in455 * decode_prio_command456 */457 458#define TNC_UNINITIALIZED 0459#define TNC_UNSYNC_STARTUP 1460#define TNC_UNSYNCED 2461#define TNC_IN_SYNC 3462 463static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)464{465 char *msg;466 467 switch (new_tnc_state) {468 default: /* gcc oh piece-o-crap ... */469 case TNC_UNSYNC_STARTUP:470 msg = "Synchronizing with TNC";471 break;472 case TNC_UNSYNCED:473 msg = "Lost synchronization with TNC\n";474 break;475 case TNC_IN_SYNC:476 msg = "Found TNC";477 break;478 }479 480 sp->tnc_state = new_tnc_state;481 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);482}483 484static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)485{486 int old_tnc_state = sp->tnc_state;487 488 if (old_tnc_state != new_tnc_state)489 __tnc_set_sync_state(sp, new_tnc_state);490}491 492static void resync_tnc(struct timer_list *t)493{494 struct sixpack *sp = from_timer(sp, t, resync_t);495 static char resync_cmd = 0xe8;496 497 /* clear any data that might have been received */498 499 sp->rx_count = 0;500 sp->rx_count_cooked = 0;501 502 /* reset state machine */503 504 sp->status = 1;505 sp->status1 = 1;506 sp->status2 = 0;507 508 /* resync the TNC */509 510 sp->led_state = 0x60;511 sp->tty->ops->write(sp->tty, &sp->led_state, 1);512 sp->tty->ops->write(sp->tty, &resync_cmd, 1);513 514 515 /* Start resync timer again -- the TNC might be still absent */516 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);517}518 519static inline int tnc_init(struct sixpack *sp)520{521 unsigned char inbyte = 0xe8;522 523 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);524 525 sp->tty->ops->write(sp->tty, &inbyte, 1);526 527 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);528 529 return 0;530}531 532/*533 * Open the high-level part of the 6pack channel.534 * This function is called by the TTY module when the535 * 6pack line discipline is called for. Because we are536 * sure the tty line exists, we only have to link it to537 * a free 6pcack channel...538 */539static int sixpack_open(struct tty_struct *tty)540{541 char *xbuff = NULL;542 struct net_device *dev;543 struct sixpack *sp;544 unsigned long len;545 int err = 0;546 547 if (!capable(CAP_NET_ADMIN))548 return -EPERM;549 if (tty->ops->write == NULL)550 return -EOPNOTSUPP;551 552 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,553 sp_setup);554 if (!dev) {555 err = -ENOMEM;556 goto out;557 }558 559 sp = netdev_priv(dev);560 sp->dev = dev;561 562 spin_lock_init(&sp->lock);563 spin_lock_init(&sp->rxlock);564 refcount_set(&sp->refcnt, 1);565 init_completion(&sp->dead);566 567 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */568 569 len = dev->mtu * 2;570 571 xbuff = kmalloc(len + 4, GFP_KERNEL);572 if (xbuff == NULL) {573 err = -ENOBUFS;574 goto out_free;575 }576 577 spin_lock_bh(&sp->lock);578 579 sp->tty = tty;580 581 sp->xbuff = xbuff;582 583 sp->rcount = 0;584 sp->rx_count = 0;585 sp->rx_count_cooked = 0;586 sp->xleft = 0;587 588 sp->flags = 0; /* Clear ESCAPE & ERROR flags */589 590 sp->duplex = 0;591 sp->tx_delay = SIXP_TXDELAY;592 sp->persistence = SIXP_PERSIST;593 sp->slottime = SIXP_SLOTTIME;594 sp->led_state = 0x60;595 sp->status = 1;596 sp->status1 = 1;597 sp->status2 = 0;598 sp->tx_enable = 0;599 600 netif_start_queue(dev);601 602 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);603 604 timer_setup(&sp->resync_t, resync_tnc, 0);605 606 spin_unlock_bh(&sp->lock);607 608 /* Done. We have linked the TTY line to a channel. */609 tty->disc_data = sp;610 tty->receive_room = 65536;611 612 /* Now we're ready to register. */613 err = register_netdev(dev);614 if (err)615 goto out_free;616 617 tnc_init(sp);618 619 return 0;620 621out_free:622 kfree(xbuff);623 624 free_netdev(dev);625 626out:627 return err;628}629 630 631/*632 * Close down a 6pack channel.633 * This means flushing out any pending queues, and then restoring the634 * TTY line discipline to what it was before it got hooked to 6pack635 * (which usually is TTY again).636 */637static void sixpack_close(struct tty_struct *tty)638{639 struct sixpack *sp;640 641 write_lock_irq(&disc_data_lock);642 sp = tty->disc_data;643 tty->disc_data = NULL;644 write_unlock_irq(&disc_data_lock);645 if (!sp)646 return;647 648 /*649 * We have now ensured that nobody can start using ap from now on, but650 * we have to wait for all existing users to finish.651 */652 if (!refcount_dec_and_test(&sp->refcnt))653 wait_for_completion(&sp->dead);654 655 /* We must stop the queue to avoid potentially scribbling656 * on the free buffers. The sp->dead completion is not sufficient657 * to protect us from sp->xbuff access.658 */659 netif_stop_queue(sp->dev);660 661 unregister_netdev(sp->dev);662 663 del_timer_sync(&sp->tx_t);664 del_timer_sync(&sp->resync_t);665 666 /* Free all 6pack frame buffers after unreg. */667 kfree(sp->xbuff);668 669 free_netdev(sp->dev);670}671 672/* Perform I/O control on an active 6pack channel. */673static int sixpack_ioctl(struct tty_struct *tty, unsigned int cmd,674 unsigned long arg)675{676 struct sixpack *sp = sp_get(tty);677 struct net_device *dev;678 unsigned int tmp, err;679 680 if (!sp)681 return -ENXIO;682 dev = sp->dev;683 684 switch(cmd) {685 case SIOCGIFNAME:686 err = copy_to_user((void __user *) arg, dev->name,687 strlen(dev->name) + 1) ? -EFAULT : 0;688 break;689 690 case SIOCGIFENCAP:691 err = put_user(0, (int __user *) arg);692 break;693 694 case SIOCSIFENCAP:695 if (get_user(tmp, (int __user *) arg)) {696 err = -EFAULT;697 break;698 }699 700 sp->mode = tmp;701 dev->addr_len = AX25_ADDR_LEN;702 dev->hard_header_len = AX25_KISS_HEADER_LEN +703 AX25_MAX_HEADER_LEN + 3;704 dev->type = ARPHRD_AX25;705 706 err = 0;707 break;708 709 case SIOCSIFHWADDR: {710 char addr[AX25_ADDR_LEN];711 712 if (copy_from_user(&addr,713 (void __user *)arg, AX25_ADDR_LEN)) {714 err = -EFAULT;715 break;716 }717 718 netif_tx_lock_bh(dev);719 __dev_addr_set(dev, &addr, AX25_ADDR_LEN);720 netif_tx_unlock_bh(dev);721 err = 0;722 break;723 }724 default:725 err = tty_mode_ioctl(tty, cmd, arg);726 }727 728 sp_put(sp);729 730 return err;731}732 733static struct tty_ldisc_ops sp_ldisc = {734 .owner = THIS_MODULE,735 .num = N_6PACK,736 .name = "6pack",737 .open = sixpack_open,738 .close = sixpack_close,739 .ioctl = sixpack_ioctl,740 .receive_buf = sixpack_receive_buf,741 .write_wakeup = sixpack_write_wakeup,742};743 744/* Initialize 6pack control device -- register 6pack line discipline */745 746static int __init sixpack_init_driver(void)747{748 int status;749 750 /* Register the provided line protocol discipline */751 status = tty_register_ldisc(&sp_ldisc);752 if (status)753 pr_err("6pack: can't register line discipline (err = %d)\n", status);754 755 return status;756}757 758static void __exit sixpack_exit_driver(void)759{760 tty_unregister_ldisc(&sp_ldisc);761}762 763/* encode an AX.25 packet into 6pack */764 765static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,766 int length, unsigned char tx_delay)767{768 int count = 0;769 unsigned char checksum = 0, buf[400];770 int raw_count = 0;771 772 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;773 tx_buf_raw[raw_count++] = SIXP_SEOF;774 775 buf[0] = tx_delay;776 for (count = 1; count < length; count++)777 buf[count] = tx_buf[count];778 779 for (count = 0; count < length; count++)780 checksum += buf[count];781 buf[length] = (unsigned char) 0xff - checksum;782 783 for (count = 0; count <= length; count++) {784 if ((count % 3) == 0) {785 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);786 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);787 } else if ((count % 3) == 1) {788 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);789 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);790 } else {791 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);792 tx_buf_raw[raw_count++] = (buf[count] >> 2);793 }794 }795 if ((length % 3) != 2)796 raw_count++;797 tx_buf_raw[raw_count++] = SIXP_SEOF;798 return raw_count;799}800 801/* decode 4 sixpack-encoded bytes into 3 data bytes */802 803static void decode_data(struct sixpack *sp, u8 inbyte)804{805 u8 *buf;806 807 if (sp->rx_count != 3) {808 sp->raw_buf[sp->rx_count++] = inbyte;809 810 return;811 }812 813 if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) {814 pr_err("6pack: cooked buffer overrun, data loss\n");815 sp->rx_count = 0;816 return;817 }818 819 buf = sp->raw_buf;820 sp->cooked_buf[sp->rx_count_cooked++] =821 buf[0] | ((buf[1] << 2) & 0xc0);822 sp->cooked_buf[sp->rx_count_cooked++] =823 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);824 sp->cooked_buf[sp->rx_count_cooked++] =825 (buf[2] & 0x03) | (inbyte << 2);826 sp->rx_count = 0;827}828 829/* identify and execute a 6pack priority command byte */830 831static void decode_prio_command(struct sixpack *sp, u8 cmd)832{833 ssize_t actual;834 835 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */836 837 /* RX and DCD flags can only be set in the same prio command,838 if the DCD flag has been set without the RX flag in the previous839 prio command. If DCD has not been set before, something in the840 transmission has gone wrong. In this case, RX and DCD are841 cleared in order to prevent the decode_data routine from842 reading further data that might be corrupt. */843 844 if (((sp->status & SIXP_DCD_MASK) == 0) &&845 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {846 if (sp->status != 1)847 printk(KERN_DEBUG "6pack: protocol violation\n");848 else849 sp->status = 0;850 cmd &= ~SIXP_RX_DCD_MASK;851 }852 sp->status = cmd & SIXP_PRIO_DATA_MASK;853 } else { /* output watchdog char if idle */854 if ((sp->status2 != 0) && (sp->duplex == 1)) {855 sp->led_state = 0x70;856 sp->tty->ops->write(sp->tty, &sp->led_state, 1);857 sp->tx_enable = 1;858 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);859 sp->xleft -= actual;860 sp->xhead += actual;861 sp->led_state = 0x60;862 sp->status2 = 0;863 864 }865 }866 867 /* needed to trigger the TNC watchdog */868 sp->tty->ops->write(sp->tty, &sp->led_state, 1);869 870 /* if the state byte has been received, the TNC is present,871 so the resync timer can be reset. */872 873 if (sp->tnc_state == TNC_IN_SYNC)874 mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);875 876 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;877}878 879/* identify and execute a standard 6pack command byte */880 881static void decode_std_command(struct sixpack *sp, u8 cmd)882{883 u8 checksum = 0, rest = 0;884 short i;885 886 switch (cmd & SIXP_CMD_MASK) { /* normal command */887 case SIXP_SEOF:888 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {889 if ((sp->status & SIXP_RX_DCD_MASK) ==890 SIXP_RX_DCD_MASK) {891 sp->led_state = 0x68;892 sp->tty->ops->write(sp->tty, &sp->led_state, 1);893 }894 } else {895 sp->led_state = 0x60;896 /* fill trailing bytes with zeroes */897 sp->tty->ops->write(sp->tty, &sp->led_state, 1);898 spin_lock_bh(&sp->rxlock);899 rest = sp->rx_count;900 if (rest != 0)901 for (i = rest; i <= 3; i++)902 decode_data(sp, 0);903 if (rest == 2)904 sp->rx_count_cooked -= 2;905 else if (rest == 3)906 sp->rx_count_cooked -= 1;907 for (i = 0; i < sp->rx_count_cooked; i++)908 checksum += sp->cooked_buf[i];909 if (checksum != SIXP_CHKSUM) {910 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);911 } else {912 sp->rcount = sp->rx_count_cooked-2;913 sp_bump(sp, 0);914 }915 sp->rx_count_cooked = 0;916 spin_unlock_bh(&sp->rxlock);917 }918 break;919 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");920 break;921 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");922 break;923 case SIXP_RX_BUF_OVL:924 printk(KERN_DEBUG "6pack: RX buffer overflow\n");925 }926}927 928/* decode a 6pack packet */929 930static void931sixpack_decode(struct sixpack *sp, const u8 *pre_rbuff, size_t count)932{933 size_t count1;934 u8 inbyte;935 936 for (count1 = 0; count1 < count; count1++) {937 inbyte = pre_rbuff[count1];938 if (inbyte == SIXP_FOUND_TNC) {939 tnc_set_sync_state(sp, TNC_IN_SYNC);940 del_timer(&sp->resync_t);941 }942 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)943 decode_prio_command(sp, inbyte);944 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)945 decode_std_command(sp, inbyte);946 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK) {947 spin_lock_bh(&sp->rxlock);948 decode_data(sp, inbyte);949 spin_unlock_bh(&sp->rxlock);950 }951 }952}953 954MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");955MODULE_DESCRIPTION("6pack driver for AX.25");956MODULE_LICENSE("GPL");957MODULE_ALIAS_LDISC(N_6PACK);958 959module_init(sixpack_init_driver);960module_exit(sixpack_exit_driver);961