1 // SPDX-License-Identifier: GPL-2.0-only
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.
7 * Authors: Andreas Könsgen <ajk@comnets.uni-bremen.de>
8 * Ralf Baechle DL5RB <ralf@linux-mips.org>
10 * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
12 * Laurence Culhane, <loz@holmes.demon.co.uk>
13 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
16 #include <linux/module.h>
17 #include <linux/uaccess.h>
18 #include <linux/bitops.h>
19 #include <linux/string.h>
21 #include <linux/interrupt.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>
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>
36 #include <linux/tcp.h>
37 #include <linux/semaphore.h>
38 #include <linux/refcount.h>
40 #define SIXPACK_VERSION "Revision: 0.3.0"
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 */
48 #define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
50 /* masks to get certain bits out of the status bytes sent by the TNC */
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
65 #define SIXP_FOUND_TNC 0xe9
66 #define SIXP_CON_ON 0x68
67 #define SIXP_DCD_MASK 0x08
68 #define SIXP_DAMA_OFF 0
70 /* default level 2 parameters */
71 #define SIXP_TXDELAY 25 /* 250 ms */
72 #define SIXP_PERSIST 50 /* in 256ths */
73 #define SIXP_SLOTTIME 10 /* 100 ms */
74 #define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */
75 #define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */
77 /* 6pack configuration. */
78 #define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
79 #define SIXP_MTU 256 /* Default MTU */
82 SIXPF_ERROR, /* Parity, etc. error */
87 struct tty_struct *tty; /* ptr to TTY structure */
88 struct net_device *dev; /* easy for intr handling */
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 */
97 unsigned char raw_buf[4];
98 unsigned char cooked_buf[400];
100 unsigned int rx_count;
101 unsigned int rx_count_cooked;
103 int mtu; /* Our mtu (to spot changes!) */
104 int buffsize; /* Max buffers sizes */
106 unsigned long flags; /* Flag values/ mode etc */
107 unsigned char mode; /* 6pack mode */
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;
121 struct timer_list tx_t;
122 struct timer_list resync_t;
124 struct completion dead;
128 #define AX25_6PACK_HEADER_LEN 0
130 static void sixpack_decode(struct sixpack *, const unsigned char[], int);
131 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
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.
139 static void sp_xmit_on_air(struct timer_list *t)
141 struct sixpack *sp = from_timer(sp, t, tx_t);
142 int actual, when = sp->slottime;
143 static unsigned char random;
145 random = random * 17 + 41;
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);
151 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
154 sp->led_state = 0x60;
155 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
158 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
161 /* ----> 6pack timer interrupt handler and friends. <---- */
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)
166 unsigned char *msg, *p = icp;
169 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
170 msg = "oversized transmit packet!";
174 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
175 msg = "oversized transmit packet!";
180 msg = "invalid KISS command";
184 if ((p[0] != 0) && (len > 2)) {
185 msg = "KISS control packet too long";
189 if ((p[0] == 0) && (len < 15)) {
190 msg = "bad AX.25 packet to transmit";
194 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
195 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
198 case 1: sp->tx_delay = p[1];
200 case 2: sp->persistence = p[1];
202 case 3: sp->slottime = p[1];
204 case 4: /* ignored */
206 case 5: sp->duplex = p[1];
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.
219 if (sp->duplex == 1) {
220 sp->led_state = 0x70;
221 sp->tty->ops->write(sp->tty, &sp->led_state, 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);
230 sp->xhead = sp->xbuff;
232 sp_xmit_on_air(&sp->tx_t);
238 sp->dev->stats.tx_dropped++;
239 netif_start_queue(sp->dev);
241 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
244 /* Encapsulate an IP datagram and kick it into a TTY queue. */
246 static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
248 struct sixpack *sp = netdev_priv(dev);
250 if (skb->protocol == htons(ETH_P_IP))
251 return ax25_ip_xmit(skb);
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);
265 static int sp_open_dev(struct net_device *dev)
267 struct sixpack *sp = netdev_priv(dev);
274 /* Close the low-level part of the 6pack channel. */
275 static int sp_close(struct net_device *dev)
277 struct sixpack *sp = netdev_priv(dev);
279 spin_lock_bh(&sp->lock);
281 /* TTY discipline is running. */
282 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
284 netif_stop_queue(dev);
285 spin_unlock_bh(&sp->lock);
290 static int sp_set_mac_address(struct net_device *dev, void *addr)
292 struct sockaddr_ax25 *sa = addr;
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);
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,
310 static void sp_setup(struct net_device *dev)
312 /* Finish setting up the DEVICE info. */
313 dev->netdev_ops = &sp_netdev_ops;
315 dev->hard_header_len = AX25_MAX_HEADER_LEN;
316 dev->header_ops = &ax25_header_ops;
318 dev->addr_len = AX25_ADDR_LEN;
319 dev->type = ARPHRD_AX25;
320 dev->tx_queue_len = 10;
322 /* Only activated in AX.25 mode */
323 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
324 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
329 /* Send one completely decapsulated IP datagram to the IP layer. */
332 * This is the routine that sends the received data to the kernel AX.25.
333 * 'cmd' is the KISS command. For AX.25 data, it is zero.
336 static void sp_bump(struct sixpack *sp, char cmd)
342 count = sp->rcount + 1;
344 sp->dev->stats.rx_bytes += count;
346 if ((skb = dev_alloc_skb(count + 1)) == NULL)
349 ptr = skb_put(skb, count + 1);
350 *ptr++ = cmd; /* KISS command */
352 memcpy(ptr, sp->cooked_buf + 1, count);
353 skb->protocol = ax25_type_trans(skb, sp->dev);
355 sp->dev->stats.rx_packets++;
360 sp->dev->stats.rx_dropped++;
364 /* ----------------------------------------------------------------------- */
367 * We have a potential race on dereferencing tty->disc_data, because the tty
368 * layer provides no locking at all - thus one cpu could be running
369 * sixpack_receive_buf while another calls sixpack_close, which zeroes
370 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
371 * best way to fix this is to use a rwlock in the tty struct, but for now we
372 * use a single global rwlock for all ttys in ppp line discipline.
374 static DEFINE_RWLOCK(disc_data_lock);
376 static struct sixpack *sp_get(struct tty_struct *tty)
380 read_lock(&disc_data_lock);
383 refcount_inc(&sp->refcnt);
384 read_unlock(&disc_data_lock);
389 static void sp_put(struct sixpack *sp)
391 if (refcount_dec_and_test(&sp->refcnt))
396 * Called by the TTY driver when there's room for more data. If we have
397 * more packets to send, we send them here.
399 static void sixpack_write_wakeup(struct tty_struct *tty)
401 struct sixpack *sp = sp_get(tty);
406 if (sp->xleft <= 0) {
407 /* Now serial buffer is almost free & we can start
408 * transmission of another packet */
409 sp->dev->stats.tx_packets++;
410 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
412 netif_wake_queue(sp->dev);
417 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
426 /* ----------------------------------------------------------------------- */
429 * Handle the 'receiver data ready' interrupt.
430 * This function is called by the tty module in the kernel when
431 * a block of 6pack data has been received, which can now be decapsulated
432 * and sent on to some IP layer for further processing.
434 static void sixpack_receive_buf(struct tty_struct *tty,
435 const unsigned char *cp, char *fp, int count)
447 /* Read the characters out of the buffer */
452 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
453 sp->dev->stats.rx_errors++;
457 sixpack_decode(sp, cp, count1);
464 * Try to resync the TNC. Called by the resync timer defined in
465 * decode_prio_command
468 #define TNC_UNINITIALIZED 0
469 #define TNC_UNSYNC_STARTUP 1
470 #define TNC_UNSYNCED 2
471 #define TNC_IN_SYNC 3
473 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
477 switch (new_tnc_state) {
478 default: /* gcc oh piece-o-crap ... */
479 case TNC_UNSYNC_STARTUP:
480 msg = "Synchronizing with TNC";
483 msg = "Lost synchronization with TNC\n";
490 sp->tnc_state = new_tnc_state;
491 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
494 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
496 int old_tnc_state = sp->tnc_state;
498 if (old_tnc_state != new_tnc_state)
499 __tnc_set_sync_state(sp, new_tnc_state);
502 static void resync_tnc(struct timer_list *t)
504 struct sixpack *sp = from_timer(sp, t, resync_t);
505 static char resync_cmd = 0xe8;
507 /* clear any data that might have been received */
510 sp->rx_count_cooked = 0;
512 /* reset state machine */
520 sp->led_state = 0x60;
521 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
522 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
525 /* Start resync timer again -- the TNC might be still absent */
526 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
529 static inline int tnc_init(struct sixpack *sp)
531 unsigned char inbyte = 0xe8;
533 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
535 sp->tty->ops->write(sp->tty, &inbyte, 1);
537 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
543 * Open the high-level part of the 6pack channel.
544 * This function is called by the TTY module when the
545 * 6pack line discipline is called for. Because we are
546 * sure the tty line exists, we only have to link it to
547 * a free 6pcack channel...
549 static int sixpack_open(struct tty_struct *tty)
551 char *rbuff = NULL, *xbuff = NULL;
552 struct net_device *dev;
557 if (!capable(CAP_NET_ADMIN))
559 if (tty->ops->write == NULL)
562 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
569 sp = netdev_priv(dev);
572 spin_lock_init(&sp->lock);
573 refcount_set(&sp->refcnt, 1);
574 init_completion(&sp->dead);
576 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
580 rbuff = kmalloc(len + 4, GFP_KERNEL);
581 xbuff = kmalloc(len + 4, GFP_KERNEL);
583 if (rbuff == NULL || xbuff == NULL) {
588 spin_lock_bh(&sp->lock);
595 sp->mtu = AX25_MTU + 73;
599 sp->rx_count_cooked = 0;
602 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
605 sp->tx_delay = SIXP_TXDELAY;
606 sp->persistence = SIXP_PERSIST;
607 sp->slottime = SIXP_SLOTTIME;
608 sp->led_state = 0x60;
614 netif_start_queue(dev);
616 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
618 timer_setup(&sp->resync_t, resync_tnc, 0);
620 spin_unlock_bh(&sp->lock);
622 /* Done. We have linked the TTY line to a channel. */
624 tty->receive_room = 65536;
626 /* Now we're ready to register. */
627 err = register_netdev(dev);
647 * Close down a 6pack channel.
648 * This means flushing out any pending queues, and then restoring the
649 * TTY line discipline to what it was before it got hooked to 6pack
650 * (which usually is TTY again).
652 static void sixpack_close(struct tty_struct *tty)
656 write_lock_irq(&disc_data_lock);
658 tty->disc_data = NULL;
659 write_unlock_irq(&disc_data_lock);
664 * We have now ensured that nobody can start using ap from now on, but
665 * we have to wait for all existing users to finish.
667 if (!refcount_dec_and_test(&sp->refcnt))
668 wait_for_completion(&sp->dead);
670 /* We must stop the queue to avoid potentially scribbling
671 * on the free buffers. The sp->dead completion is not sufficient
672 * to protect us from sp->xbuff access.
674 netif_stop_queue(sp->dev);
676 unregister_netdev(sp->dev);
678 del_timer_sync(&sp->tx_t);
679 del_timer_sync(&sp->resync_t);
681 /* Free all 6pack frame buffers after unreg. */
685 free_netdev(sp->dev);
688 /* Perform I/O control on an active 6pack channel. */
689 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
690 unsigned int cmd, unsigned long arg)
692 struct sixpack *sp = sp_get(tty);
693 struct net_device *dev;
694 unsigned int tmp, err;
702 err = copy_to_user((void __user *) arg, dev->name,
703 strlen(dev->name) + 1) ? -EFAULT : 0;
707 err = put_user(0, (int __user *) arg);
711 if (get_user(tmp, (int __user *) arg)) {
717 dev->addr_len = AX25_ADDR_LEN;
718 dev->hard_header_len = AX25_KISS_HEADER_LEN +
719 AX25_MAX_HEADER_LEN + 3;
720 dev->type = ARPHRD_AX25;
725 case SIOCSIFHWADDR: {
726 char addr[AX25_ADDR_LEN];
728 if (copy_from_user(&addr,
729 (void __user *) arg, AX25_ADDR_LEN)) {
734 netif_tx_lock_bh(dev);
735 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
736 netif_tx_unlock_bh(dev);
743 err = tty_mode_ioctl(tty, file, cmd, arg);
751 static struct tty_ldisc_ops sp_ldisc = {
752 .owner = THIS_MODULE,
753 .magic = TTY_LDISC_MAGIC,
755 .open = sixpack_open,
756 .close = sixpack_close,
757 .ioctl = sixpack_ioctl,
758 .receive_buf = sixpack_receive_buf,
759 .write_wakeup = sixpack_write_wakeup,
762 /* Initialize 6pack control device -- register 6pack line discipline */
764 static const char msg_banner[] __initconst = KERN_INFO \
765 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
766 static const char msg_regfail[] __initconst = KERN_ERR \
767 "6pack: can't register line discipline (err = %d)\n";
769 static int __init sixpack_init_driver(void)
775 /* Register the provided line protocol discipline */
776 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
777 printk(msg_regfail, status);
782 static const char msg_unregfail[] = KERN_ERR \
783 "6pack: can't unregister line discipline (err = %d)\n";
785 static void __exit sixpack_exit_driver(void)
789 if ((ret = tty_unregister_ldisc(N_6PACK)))
790 printk(msg_unregfail, ret);
793 /* encode an AX.25 packet into 6pack */
795 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
796 int length, unsigned char tx_delay)
799 unsigned char checksum = 0, buf[400];
802 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
803 tx_buf_raw[raw_count++] = SIXP_SEOF;
806 for (count = 1; count < length; count++)
807 buf[count] = tx_buf[count];
809 for (count = 0; count < length; count++)
810 checksum += buf[count];
811 buf[length] = (unsigned char) 0xff - checksum;
813 for (count = 0; count <= length; count++) {
814 if ((count % 3) == 0) {
815 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
816 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
817 } else if ((count % 3) == 1) {
818 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
819 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
821 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
822 tx_buf_raw[raw_count++] = (buf[count] >> 2);
825 if ((length % 3) != 2)
827 tx_buf_raw[raw_count++] = SIXP_SEOF;
831 /* decode 4 sixpack-encoded bytes into 3 data bytes */
833 static void decode_data(struct sixpack *sp, unsigned char inbyte)
837 if (sp->rx_count != 3) {
838 sp->raw_buf[sp->rx_count++] = inbyte;
843 if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) {
844 pr_err("6pack: cooked buffer overrun, data loss\n");
850 sp->cooked_buf[sp->rx_count_cooked++] =
851 buf[0] | ((buf[1] << 2) & 0xc0);
852 sp->cooked_buf[sp->rx_count_cooked++] =
853 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
854 sp->cooked_buf[sp->rx_count_cooked++] =
855 (buf[2] & 0x03) | (inbyte << 2);
859 /* identify and execute a 6pack priority command byte */
861 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
865 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
867 /* RX and DCD flags can only be set in the same prio command,
868 if the DCD flag has been set without the RX flag in the previous
869 prio command. If DCD has not been set before, something in the
870 transmission has gone wrong. In this case, RX and DCD are
871 cleared in order to prevent the decode_data routine from
872 reading further data that might be corrupt. */
874 if (((sp->status & SIXP_DCD_MASK) == 0) &&
875 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
877 printk(KERN_DEBUG "6pack: protocol violation\n");
880 cmd &= ~SIXP_RX_DCD_MASK;
882 sp->status = cmd & SIXP_PRIO_DATA_MASK;
883 } else { /* output watchdog char if idle */
884 if ((sp->status2 != 0) && (sp->duplex == 1)) {
885 sp->led_state = 0x70;
886 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
888 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
891 sp->led_state = 0x60;
897 /* needed to trigger the TNC watchdog */
898 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
900 /* if the state byte has been received, the TNC is present,
901 so the resync timer can be reset. */
903 if (sp->tnc_state == TNC_IN_SYNC)
904 mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
906 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
909 /* identify and execute a standard 6pack command byte */
911 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
913 unsigned char checksum = 0, rest = 0;
916 switch (cmd & SIXP_CMD_MASK) { /* normal command */
918 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
919 if ((sp->status & SIXP_RX_DCD_MASK) ==
921 sp->led_state = 0x68;
922 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
925 sp->led_state = 0x60;
926 /* fill trailing bytes with zeroes */
927 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
930 for (i = rest; i <= 3; i++)
933 sp->rx_count_cooked -= 2;
935 sp->rx_count_cooked -= 1;
936 for (i = 0; i < sp->rx_count_cooked; i++)
937 checksum += sp->cooked_buf[i];
938 if (checksum != SIXP_CHKSUM) {
939 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
941 sp->rcount = sp->rx_count_cooked-2;
944 sp->rx_count_cooked = 0;
947 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
949 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
951 case SIXP_RX_BUF_OVL:
952 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
956 /* decode a 6pack packet */
959 sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
961 unsigned char inbyte;
964 for (count1 = 0; count1 < count; count1++) {
965 inbyte = pre_rbuff[count1];
966 if (inbyte == SIXP_FOUND_TNC) {
967 tnc_set_sync_state(sp, TNC_IN_SYNC);
968 del_timer(&sp->resync_t);
970 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
971 decode_prio_command(sp, inbyte);
972 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
973 decode_std_command(sp, inbyte);
974 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
975 decode_data(sp, inbyte);
979 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
980 MODULE_DESCRIPTION("6pack driver for AX.25");
981 MODULE_LICENSE("GPL");
982 MODULE_ALIAS_LDISC(N_6PACK);
984 module_init(sixpack_init_driver);
985 module_exit(sixpack_exit_driver);