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.
6 * Authors: Andreas K霵sgen <ajk@iehk.rwth-aachen.de>
7 * Ralf Baechle DL5RB <ralf@linux-mips.org>
9 * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
11 * Laurence Culhane, <loz@holmes.demon.co.uk>
12 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
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>
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>
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>
35 #include <linux/tcp.h>
36 #include <asm/semaphore.h>
37 #include <asm/atomic.h>
39 #define SIXPACK_VERSION "Revision: 0.3.0"
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 */
47 #define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
49 /* masks to get certain bits out of the status bytes sent by the TNC */
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
64 #define SIXP_FOUND_TNC 0xe9
65 #define SIXP_CON_ON 0x68
66 #define SIXP_DCD_MASK 0x08
67 #define SIXP_DAMA_OFF 0
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 */
76 /* 6pack configuration. */
77 #define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
78 #define SIXP_MTU 256 /* Default MTU */
81 SIXPF_ERROR, /* Parity, etc. error */
86 struct tty_struct *tty; /* ptr to TTY structure */
87 struct net_device *dev; /* easy for intr handling */
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 */
96 unsigned char raw_buf[4];
97 unsigned char cooked_buf[400];
99 unsigned int rx_count;
100 unsigned int rx_count_cooked;
102 /* 6pack interface statistics. */
103 struct net_device_stats stats;
105 int mtu; /* Our mtu (to spot changes!) */
106 int buffsize; /* Max buffers sizes */
108 unsigned long flags; /* Flag values/ mode etc */
109 unsigned char mode; /* 6pack mode */
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;
123 struct timer_list tx_t;
124 struct timer_list resync_t;
126 struct semaphore dead_sem;
130 #define AX25_6PACK_HEADER_LEN 0
132 static void sixpack_decode(struct sixpack *, unsigned char[], int);
133 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
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.
141 static void sp_xmit_on_air(unsigned long channel)
143 struct sixpack *sp = (struct sixpack *) channel;
144 int actual, when = sp->slottime;
145 static unsigned char random;
147 random = random * 17 + 41;
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);
153 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
156 sp->led_state = 0x60;
157 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
160 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
163 /* ----> 6pack timer interrupt handler and friends. <---- */
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)
168 unsigned char *msg, *p = icp;
171 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
172 msg = "oversized transmit packet!";
176 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
177 msg = "oversized transmit packet!";
182 msg = "invalid KISS command";
186 if ((p[0] != 0) && (len > 2)) {
187 msg = "KISS control packet too long";
191 if ((p[0] == 0) && (len < 15)) {
192 msg = "bad AX.25 packet to transmit";
196 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
197 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
200 case 1: sp->tx_delay = p[1];
202 case 2: sp->persistence = p[1];
204 case 3: sp->slottime = p[1];
206 case 4: /* ignored */
208 case 5: sp->duplex = p[1];
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.
221 if (sp->duplex == 1) {
222 sp->led_state = 0x70;
223 sp->tty->driver->write(sp->tty, &sp->led_state, 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);
232 sp->xhead = sp->xbuff;
234 sp_xmit_on_air((unsigned long)sp);
240 sp->stats.tx_dropped++;
241 netif_start_queue(sp->dev);
243 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
246 /* Encapsulate an IP datagram and kick it into a TTY queue. */
248 static int sp_xmit(struct sk_buff *skb, struct net_device *dev)
250 struct sixpack *sp = netdev_priv(dev);
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);
264 static int sp_open_dev(struct net_device *dev)
266 struct sixpack *sp = netdev_priv(dev);
273 /* Close the low-level part of the 6pack channel. */
274 static int sp_close(struct net_device *dev)
276 struct sixpack *sp = netdev_priv(dev);
278 spin_lock_bh(&sp->lock);
280 /* TTY discipline is running. */
281 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
283 netif_stop_queue(dev);
284 spin_unlock_bh(&sp->lock);
289 /* Return the frame type ID */
290 static int sp_header(struct sk_buff *skb, struct net_device *dev,
291 unsigned short type, void *daddr, void *saddr, unsigned len)
294 if (type != htons(ETH_P_AX25))
295 return ax25_hard_header(skb, dev, type, daddr, saddr, len);
300 static struct net_device_stats *sp_get_stats(struct net_device *dev)
302 struct sixpack *sp = netdev_priv(dev);
306 static int sp_set_mac_address(struct net_device *dev, void *addr)
308 struct sockaddr_ax25 *sa = addr;
310 netif_tx_lock_bh(dev);
311 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
312 netif_tx_unlock_bh(dev);
317 static int sp_rebuild_header(struct sk_buff *skb)
320 return ax25_rebuild_header(skb);
326 static void sp_setup(struct net_device *dev)
328 /* Finish setting up the DEVICE info. */
330 dev->hard_start_xmit = sp_xmit;
331 dev->open = sp_open_dev;
332 dev->destructor = free_netdev;
333 dev->stop = sp_close;
334 dev->hard_header = sp_header;
335 dev->get_stats = sp_get_stats;
336 dev->set_mac_address = sp_set_mac_address;
337 dev->hard_header_len = AX25_MAX_HEADER_LEN;
338 dev->addr_len = AX25_ADDR_LEN;
339 dev->type = ARPHRD_AX25;
340 dev->tx_queue_len = 10;
341 dev->rebuild_header = sp_rebuild_header;
342 dev->tx_timeout = NULL;
344 /* Only activated in AX.25 mode */
345 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
346 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
351 /* Send one completely decapsulated IP datagram to the IP layer. */
354 * This is the routine that sends the received data to the kernel AX.25.
355 * 'cmd' is the KISS command. For AX.25 data, it is zero.
358 static void sp_bump(struct sixpack *sp, char cmd)
364 count = sp->rcount + 1;
366 sp->stats.rx_bytes += count;
368 if ((skb = dev_alloc_skb(count)) == NULL)
371 ptr = skb_put(skb, count);
372 *ptr++ = cmd; /* KISS command */
374 memcpy(ptr, sp->cooked_buf + 1, count);
375 skb->protocol = ax25_type_trans(skb, sp->dev);
377 sp->dev->last_rx = jiffies;
378 sp->stats.rx_packets++;
383 sp->stats.rx_dropped++;
387 /* ----------------------------------------------------------------------- */
390 * We have a potential race on dereferencing tty->disc_data, because the tty
391 * layer provides no locking at all - thus one cpu could be running
392 * sixpack_receive_buf while another calls sixpack_close, which zeroes
393 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
394 * best way to fix this is to use a rwlock in the tty struct, but for now we
395 * use a single global rwlock for all ttys in ppp line discipline.
397 static DEFINE_RWLOCK(disc_data_lock);
399 static struct sixpack *sp_get(struct tty_struct *tty)
403 read_lock(&disc_data_lock);
406 atomic_inc(&sp->refcnt);
407 read_unlock(&disc_data_lock);
412 static void sp_put(struct sixpack *sp)
414 if (atomic_dec_and_test(&sp->refcnt))
419 * Called by the TTY driver when there's room for more data. If we have
420 * more packets to send, we send them here.
422 static void sixpack_write_wakeup(struct tty_struct *tty)
424 struct sixpack *sp = sp_get(tty);
429 if (sp->xleft <= 0) {
430 /* Now serial buffer is almost free & we can start
431 * transmission of another packet */
432 sp->stats.tx_packets++;
433 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
435 netif_wake_queue(sp->dev);
440 actual = tty->driver->write(tty, sp->xhead, sp->xleft);
449 /* ----------------------------------------------------------------------- */
452 * Handle the 'receiver data ready' interrupt.
453 * This function is called by the 'tty_io' module in the kernel when
454 * a block of 6pack data has been received, which can now be decapsulated
455 * and sent on to some IP layer for further processing.
457 static void sixpack_receive_buf(struct tty_struct *tty,
458 const unsigned char *cp, char *fp, int count)
461 unsigned char buf[512];
471 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
473 /* Read the characters out of the buffer */
479 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
480 sp->stats.rx_errors++;
484 sixpack_decode(sp, buf, count1);
487 if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
488 && tty->driver->unthrottle)
489 tty->driver->unthrottle(tty);
493 * Try to resync the TNC. Called by the resync timer defined in
494 * decode_prio_command
497 #define TNC_UNINITIALIZED 0
498 #define TNC_UNSYNC_STARTUP 1
499 #define TNC_UNSYNCED 2
500 #define TNC_IN_SYNC 3
502 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
506 switch (new_tnc_state) {
507 default: /* gcc oh piece-o-crap ... */
508 case TNC_UNSYNC_STARTUP:
509 msg = "Synchronizing with TNC";
512 msg = "Lost synchronization with TNC\n";
519 sp->tnc_state = new_tnc_state;
520 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
523 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
525 int old_tnc_state = sp->tnc_state;
527 if (old_tnc_state != new_tnc_state)
528 __tnc_set_sync_state(sp, new_tnc_state);
531 static void resync_tnc(unsigned long channel)
533 struct sixpack *sp = (struct sixpack *) channel;
534 static char resync_cmd = 0xe8;
536 /* clear any data that might have been received */
539 sp->rx_count_cooked = 0;
541 /* reset state machine */
549 sp->led_state = 0x60;
550 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
551 sp->tty->driver->write(sp->tty, &resync_cmd, 1);
554 /* Start resync timer again -- the TNC might be still absent */
556 del_timer(&sp->resync_t);
557 sp->resync_t.data = (unsigned long) sp;
558 sp->resync_t.function = resync_tnc;
559 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
560 add_timer(&sp->resync_t);
563 static inline int tnc_init(struct sixpack *sp)
565 unsigned char inbyte = 0xe8;
567 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
569 sp->tty->driver->write(sp->tty, &inbyte, 1);
571 del_timer(&sp->resync_t);
572 sp->resync_t.data = (unsigned long) sp;
573 sp->resync_t.function = resync_tnc;
574 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
575 add_timer(&sp->resync_t);
581 * Open the high-level part of the 6pack channel.
582 * This function is called by the TTY module when the
583 * 6pack line discipline is called for. Because we are
584 * sure the tty line exists, we only have to link it to
585 * a free 6pcack channel...
587 static int sixpack_open(struct tty_struct *tty)
589 char *rbuff = NULL, *xbuff = NULL;
590 struct net_device *dev;
595 if (!capable(CAP_NET_ADMIN))
598 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
604 sp = netdev_priv(dev);
607 spin_lock_init(&sp->lock);
608 atomic_set(&sp->refcnt, 1);
609 init_MUTEX_LOCKED(&sp->dead_sem);
611 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
615 rbuff = kmalloc(len + 4, GFP_KERNEL);
616 xbuff = kmalloc(len + 4, GFP_KERNEL);
618 if (rbuff == NULL || xbuff == NULL) {
623 spin_lock_bh(&sp->lock);
630 sp->mtu = AX25_MTU + 73;
634 sp->rx_count_cooked = 0;
637 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
640 sp->tx_delay = SIXP_TXDELAY;
641 sp->persistence = SIXP_PERSIST;
642 sp->slottime = SIXP_SLOTTIME;
643 sp->led_state = 0x60;
649 netif_start_queue(dev);
651 init_timer(&sp->tx_t);
652 sp->tx_t.function = sp_xmit_on_air;
653 sp->tx_t.data = (unsigned long) sp;
655 init_timer(&sp->resync_t);
657 spin_unlock_bh(&sp->lock);
659 /* Done. We have linked the TTY line to a channel. */
661 tty->receive_room = 65536;
663 /* Now we're ready to register. */
664 if (register_netdev(dev))
684 * Close down a 6pack channel.
685 * This means flushing out any pending queues, and then restoring the
686 * TTY line discipline to what it was before it got hooked to 6pack
687 * (which usually is TTY again).
689 static void sixpack_close(struct tty_struct *tty)
693 write_lock(&disc_data_lock);
695 tty->disc_data = NULL;
696 write_unlock(&disc_data_lock);
701 * We have now ensured that nobody can start using ap from now on, but
702 * we have to wait for all existing users to finish.
704 if (!atomic_dec_and_test(&sp->refcnt))
707 unregister_netdev(sp->dev);
709 del_timer(&sp->tx_t);
710 del_timer(&sp->resync_t);
712 /* Free all 6pack frame buffers. */
717 /* Perform I/O control on an active 6pack channel. */
718 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
719 unsigned int cmd, unsigned long arg)
721 struct sixpack *sp = sp_get(tty);
722 struct net_device *dev = sp->dev;
723 unsigned int tmp, err;
730 err = copy_to_user((void __user *) arg, dev->name,
731 strlen(dev->name) + 1) ? -EFAULT : 0;
735 err = put_user(0, (int __user *) arg);
739 if (get_user(tmp, (int __user *) arg)) {
745 dev->addr_len = AX25_ADDR_LEN;
746 dev->hard_header_len = AX25_KISS_HEADER_LEN +
747 AX25_MAX_HEADER_LEN + 3;
748 dev->type = ARPHRD_AX25;
753 case SIOCSIFHWADDR: {
754 char addr[AX25_ADDR_LEN];
756 if (copy_from_user(&addr,
757 (void __user *) arg, AX25_ADDR_LEN)) {
762 netif_tx_lock_bh(dev);
763 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
764 netif_tx_unlock_bh(dev);
770 /* Allow stty to read, but not set, the serial port */
773 err = n_tty_ioctl(tty, (struct file *) file, cmd, arg);
785 static struct tty_ldisc sp_ldisc = {
786 .owner = THIS_MODULE,
787 .magic = TTY_LDISC_MAGIC,
789 .open = sixpack_open,
790 .close = sixpack_close,
791 .ioctl = sixpack_ioctl,
792 .receive_buf = sixpack_receive_buf,
793 .write_wakeup = sixpack_write_wakeup,
796 /* Initialize 6pack control device -- register 6pack line discipline */
798 static char msg_banner[] __initdata = KERN_INFO \
799 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
800 static char msg_regfail[] __initdata = KERN_ERR \
801 "6pack: can't register line discipline (err = %d)\n";
803 static int __init sixpack_init_driver(void)
809 /* Register the provided line protocol discipline */
810 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
811 printk(msg_regfail, status);
816 static const char msg_unregfail[] __exitdata = KERN_ERR \
817 "6pack: can't unregister line discipline (err = %d)\n";
819 static void __exit sixpack_exit_driver(void)
823 if ((ret = tty_unregister_ldisc(N_6PACK)))
824 printk(msg_unregfail, ret);
827 /* encode an AX.25 packet into 6pack */
829 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
830 int length, unsigned char tx_delay)
833 unsigned char checksum = 0, buf[400];
836 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
837 tx_buf_raw[raw_count++] = SIXP_SEOF;
840 for (count = 1; count < length; count++)
841 buf[count] = tx_buf[count];
843 for (count = 0; count < length; count++)
844 checksum += buf[count];
845 buf[length] = (unsigned char) 0xff - checksum;
847 for (count = 0; count <= length; count++) {
848 if ((count % 3) == 0) {
849 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
850 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
851 } else if ((count % 3) == 1) {
852 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
853 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
855 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
856 tx_buf_raw[raw_count++] = (buf[count] >> 2);
859 if ((length % 3) != 2)
861 tx_buf_raw[raw_count++] = SIXP_SEOF;
865 /* decode 4 sixpack-encoded bytes into 3 data bytes */
867 static void decode_data(struct sixpack *sp, unsigned char inbyte)
871 if (sp->rx_count != 3) {
872 sp->raw_buf[sp->rx_count++] = inbyte;
878 sp->cooked_buf[sp->rx_count_cooked++] =
879 buf[0] | ((buf[1] << 2) & 0xc0);
880 sp->cooked_buf[sp->rx_count_cooked++] =
881 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
882 sp->cooked_buf[sp->rx_count_cooked++] =
883 (buf[2] & 0x03) | (inbyte << 2);
887 /* identify and execute a 6pack priority command byte */
889 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
891 unsigned char channel;
894 channel = cmd & SIXP_CHN_MASK;
895 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
897 /* RX and DCD flags can only be set in the same prio command,
898 if the DCD flag has been set without the RX flag in the previous
899 prio command. If DCD has not been set before, something in the
900 transmission has gone wrong. In this case, RX and DCD are
901 cleared in order to prevent the decode_data routine from
902 reading further data that might be corrupt. */
904 if (((sp->status & SIXP_DCD_MASK) == 0) &&
905 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
907 printk(KERN_DEBUG "6pack: protocol violation\n");
910 cmd &= ~SIXP_RX_DCD_MASK;
912 sp->status = cmd & SIXP_PRIO_DATA_MASK;
913 } else { /* output watchdog char if idle */
914 if ((sp->status2 != 0) && (sp->duplex == 1)) {
915 sp->led_state = 0x70;
916 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
918 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
921 sp->led_state = 0x60;
927 /* needed to trigger the TNC watchdog */
928 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
930 /* if the state byte has been received, the TNC is present,
931 so the resync timer can be reset. */
933 if (sp->tnc_state == TNC_IN_SYNC) {
934 del_timer(&sp->resync_t);
935 sp->resync_t.data = (unsigned long) sp;
936 sp->resync_t.function = resync_tnc;
937 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
938 add_timer(&sp->resync_t);
941 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
944 /* identify and execute a standard 6pack command byte */
946 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
948 unsigned char checksum = 0, rest = 0, channel;
951 channel = cmd & SIXP_CHN_MASK;
952 switch (cmd & SIXP_CMD_MASK) { /* normal command */
954 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
955 if ((sp->status & SIXP_RX_DCD_MASK) ==
957 sp->led_state = 0x68;
958 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
961 sp->led_state = 0x60;
962 /* fill trailing bytes with zeroes */
963 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
966 for (i = rest; i <= 3; i++)
969 sp->rx_count_cooked -= 2;
971 sp->rx_count_cooked -= 1;
972 for (i = 0; i < sp->rx_count_cooked; i++)
973 checksum += sp->cooked_buf[i];
974 if (checksum != SIXP_CHKSUM) {
975 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
977 sp->rcount = sp->rx_count_cooked-2;
980 sp->rx_count_cooked = 0;
983 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
985 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
987 case SIXP_RX_BUF_OVL:
988 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
992 /* decode a 6pack packet */
995 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
997 unsigned char inbyte;
1000 for (count1 = 0; count1 < count; count1++) {
1001 inbyte = pre_rbuff[count1];
1002 if (inbyte == SIXP_FOUND_TNC) {
1003 tnc_set_sync_state(sp, TNC_IN_SYNC);
1004 del_timer(&sp->resync_t);
1006 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1007 decode_prio_command(sp, inbyte);
1008 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1009 decode_std_command(sp, inbyte);
1010 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1011 decode_data(sp, inbyte);
1015 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1016 MODULE_DESCRIPTION("6pack driver for AX.25");
1017 MODULE_LICENSE("GPL");
1018 MODULE_ALIAS_LDISC(N_6PACK);
1020 module_init(sixpack_init_driver);
1021 module_exit(sixpack_exit_driver);