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 Könsgen <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/config.h>
16 #include <linux/module.h>
17 #include <asm/system.h>
18 #include <asm/uaccess.h>
19 #include <linux/bitops.h>
20 #include <linux/string.h>
22 #include <linux/interrupt.h>
24 #include <linux/tty.h>
25 #include <linux/errno.h>
26 #include <linux/netdevice.h>
27 #include <linux/timer.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 <asm/semaphore.h>
38 #include <asm/atomic.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 (HZ/4) /* in 1 s */
72 #define SIXP_PERSIST 50 /* in 256ths */
73 #define SIXP_SLOTTIME (HZ/10) /* in 1 s */
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 /* 6pack interface statistics. */
104 struct net_device_stats stats;
106 int mtu; /* Our mtu (to spot changes!) */
107 int buffsize; /* Max buffers sizes */
109 unsigned long flags; /* Flag values/ mode etc */
110 unsigned char mode; /* 6pack mode */
113 unsigned char tx_delay;
114 unsigned char persistence;
115 unsigned char slottime;
116 unsigned char duplex;
117 unsigned char led_state;
118 unsigned char status;
119 unsigned char status1;
120 unsigned char status2;
121 unsigned char tx_enable;
122 unsigned char tnc_state;
124 struct timer_list tx_t;
125 struct timer_list resync_t;
127 struct semaphore dead_sem;
131 #define AX25_6PACK_HEADER_LEN 0
133 static void sixpack_decode(struct sixpack *, unsigned char[], int);
134 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
137 * Perform the persistence/slottime algorithm for CSMA access. If the
138 * persistence check was successful, write the data to the serial driver.
139 * Note that in case of DAMA operation, the data is not sent here.
142 static void sp_xmit_on_air(unsigned long channel)
144 struct sixpack *sp = (struct sixpack *) channel;
145 int actual, when = sp->slottime;
146 static unsigned char random;
148 random = random * 17 + 41;
150 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
151 sp->led_state = 0x70;
152 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
154 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
157 sp->led_state = 0x60;
158 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
161 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
164 /* ----> 6pack timer interrupt handler and friends. <---- */
166 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */
167 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
169 unsigned char *msg, *p = icp;
172 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
173 msg = "oversized transmit packet!";
177 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
178 msg = "oversized transmit packet!";
183 msg = "invalid KISS command";
187 if ((p[0] != 0) && (len > 2)) {
188 msg = "KISS control packet too long";
192 if ((p[0] == 0) && (len < 15)) {
193 msg = "bad AX.25 packet to transmit";
197 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
198 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
201 case 1: sp->tx_delay = p[1];
203 case 2: sp->persistence = p[1];
205 case 3: sp->slottime = p[1];
207 case 4: /* ignored */
209 case 5: sp->duplex = p[1];
217 * In case of fullduplex or DAMA operation, we don't take care about the
218 * state of the DCD or of any timers, as the determination of the
219 * correct time to send is the job of the AX.25 layer. We send
220 * immediately after data has arrived.
222 if (sp->duplex == 1) {
223 sp->led_state = 0x70;
224 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
226 actual = sp->tty->driver->write(sp->tty, sp->xbuff, count);
227 sp->xleft = count - actual;
228 sp->xhead = sp->xbuff + actual;
229 sp->led_state = 0x60;
230 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
233 sp->xhead = sp->xbuff;
235 sp_xmit_on_air((unsigned long)sp);
241 sp->stats.tx_dropped++;
242 netif_start_queue(sp->dev);
244 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
247 /* Encapsulate an IP datagram and kick it into a TTY queue. */
249 static int sp_xmit(struct sk_buff *skb, struct net_device *dev)
251 struct sixpack *sp = netdev_priv(dev);
253 spin_lock_bh(&sp->lock);
254 /* We were not busy, so we are now... :-) */
255 netif_stop_queue(dev);
256 sp->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 /* Return the frame type ID */
291 static int sp_header(struct sk_buff *skb, struct net_device *dev,
292 unsigned short type, void *daddr, void *saddr, unsigned len)
295 if (type != htons(ETH_P_AX25))
296 return ax25_encapsulate(skb, dev, type, daddr, saddr, len);
301 static struct net_device_stats *sp_get_stats(struct net_device *dev)
303 struct sixpack *sp = netdev_priv(dev);
307 static int sp_set_mac_address(struct net_device *dev, void *addr)
309 struct sockaddr_ax25 *sa = addr;
311 if (sa->sax25_family != AF_AX25)
314 if (!sa->sax25_ndigis)
317 spin_lock_irq(&dev->xmit_lock);
318 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
319 spin_unlock_irq(&dev->xmit_lock);
324 static int sp_rebuild_header(struct sk_buff *skb)
327 return ax25_rebuild_header(skb);
333 static void sp_setup(struct net_device *dev)
335 static char ax25_bcast[AX25_ADDR_LEN] =
336 {'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
337 static char ax25_test[AX25_ADDR_LEN] =
338 {'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};
340 /* Finish setting up the DEVICE info. */
342 dev->hard_start_xmit = sp_xmit;
343 dev->open = sp_open_dev;
344 dev->destructor = free_netdev;
345 dev->stop = sp_close;
346 dev->hard_header = sp_header;
347 dev->get_stats = sp_get_stats;
348 dev->set_mac_address = sp_set_mac_address;
349 dev->hard_header_len = AX25_MAX_HEADER_LEN;
350 dev->addr_len = AX25_ADDR_LEN;
351 dev->type = ARPHRD_AX25;
352 dev->tx_queue_len = 10;
353 dev->rebuild_header = sp_rebuild_header;
354 dev->tx_timeout = NULL;
356 /* Only activated in AX.25 mode */
357 memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);
358 memcpy(dev->dev_addr, ax25_test, AX25_ADDR_LEN);
360 SET_MODULE_OWNER(dev);
365 /* Send one completely decapsulated IP datagram to the IP layer. */
368 * This is the routine that sends the received data to the kernel AX.25.
369 * 'cmd' is the KISS command. For AX.25 data, it is zero.
372 static void sp_bump(struct sixpack *sp, char cmd)
378 count = sp->rcount + 1;
380 sp->stats.rx_bytes += count;
382 if ((skb = dev_alloc_skb(count)) == NULL)
385 ptr = skb_put(skb, count);
386 *ptr++ = cmd; /* KISS command */
388 memcpy(ptr, sp->cooked_buf + 1, count);
389 skb->protocol = ax25_type_trans(skb, sp->dev);
391 sp->dev->last_rx = jiffies;
392 sp->stats.rx_packets++;
397 sp->stats.rx_dropped++;
401 /* ----------------------------------------------------------------------- */
404 * We have a potential race on dereferencing tty->disc_data, because the tty
405 * layer provides no locking at all - thus one cpu could be running
406 * sixpack_receive_buf while another calls sixpack_close, which zeroes
407 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
408 * best way to fix this is to use a rwlock in the tty struct, but for now we
409 * use a single global rwlock for all ttys in ppp line discipline.
411 static DEFINE_RWLOCK(disc_data_lock);
413 static struct sixpack *sp_get(struct tty_struct *tty)
417 read_lock(&disc_data_lock);
420 atomic_inc(&sp->refcnt);
421 read_unlock(&disc_data_lock);
426 static void sp_put(struct sixpack *sp)
428 if (atomic_dec_and_test(&sp->refcnt))
433 * Called by the TTY driver when there's room for more data. If we have
434 * more packets to send, we send them here.
436 static void sixpack_write_wakeup(struct tty_struct *tty)
438 struct sixpack *sp = sp_get(tty);
443 if (sp->xleft <= 0) {
444 /* Now serial buffer is almost free & we can start
445 * transmission of another packet */
446 sp->stats.tx_packets++;
447 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
449 netif_wake_queue(sp->dev);
454 actual = tty->driver->write(tty, sp->xhead, sp->xleft);
463 /* ----------------------------------------------------------------------- */
465 static int sixpack_receive_room(struct tty_struct *tty)
467 return 65536; /* We can handle an infinite amount of data. :-) */
471 * Handle the 'receiver data ready' interrupt.
472 * This function is called by the 'tty_io' module in the kernel when
473 * a block of 6pack data has been received, which can now be decapsulated
474 * and sent on to some IP layer for further processing.
476 static void sixpack_receive_buf(struct tty_struct *tty,
477 const unsigned char *cp, char *fp, int count)
480 unsigned char buf[512];
490 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
492 /* Read the characters out of the buffer */
498 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
499 sp->stats.rx_errors++;
503 sixpack_decode(sp, buf, count1);
506 if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
507 && tty->driver->unthrottle)
508 tty->driver->unthrottle(tty);
512 * Try to resync the TNC. Called by the resync timer defined in
513 * decode_prio_command
516 #define TNC_UNINITIALIZED 0
517 #define TNC_UNSYNC_STARTUP 1
518 #define TNC_UNSYNCED 2
519 #define TNC_IN_SYNC 3
521 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
525 switch (new_tnc_state) {
526 default: /* gcc oh piece-o-crap ... */
527 case TNC_UNSYNC_STARTUP:
528 msg = "Synchronizing with TNC";
531 msg = "Lost synchronization with TNC\n";
538 sp->tnc_state = new_tnc_state;
539 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
542 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
544 int old_tnc_state = sp->tnc_state;
546 if (old_tnc_state != new_tnc_state)
547 __tnc_set_sync_state(sp, new_tnc_state);
550 static void resync_tnc(unsigned long channel)
552 struct sixpack *sp = (struct sixpack *) channel;
553 static char resync_cmd = 0xe8;
555 /* clear any data that might have been received */
558 sp->rx_count_cooked = 0;
560 /* reset state machine */
568 sp->led_state = 0x60;
569 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
570 sp->tty->driver->write(sp->tty, &resync_cmd, 1);
573 /* Start resync timer again -- the TNC might be still absent */
575 del_timer(&sp->resync_t);
576 sp->resync_t.data = (unsigned long) sp;
577 sp->resync_t.function = resync_tnc;
578 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
579 add_timer(&sp->resync_t);
582 static inline int tnc_init(struct sixpack *sp)
584 unsigned char inbyte = 0xe8;
586 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
588 sp->tty->driver->write(sp->tty, &inbyte, 1);
590 del_timer(&sp->resync_t);
591 sp->resync_t.data = (unsigned long) sp;
592 sp->resync_t.function = resync_tnc;
593 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
594 add_timer(&sp->resync_t);
600 * Open the high-level part of the 6pack channel.
601 * This function is called by the TTY module when the
602 * 6pack line discipline is called for. Because we are
603 * sure the tty line exists, we only have to link it to
604 * a free 6pcack channel...
606 static int sixpack_open(struct tty_struct *tty)
608 char *rbuff = NULL, *xbuff = NULL;
609 struct net_device *dev;
614 if (!capable(CAP_NET_ADMIN))
617 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
623 sp = netdev_priv(dev);
626 spin_lock_init(&sp->lock);
627 atomic_set(&sp->refcnt, 1);
628 init_MUTEX_LOCKED(&sp->dead_sem);
630 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
634 rbuff = kmalloc(len + 4, GFP_KERNEL);
635 xbuff = kmalloc(len + 4, GFP_KERNEL);
637 if (rbuff == NULL || xbuff == NULL) {
642 spin_lock_bh(&sp->lock);
649 sp->mtu = AX25_MTU + 73;
653 sp->rx_count_cooked = 0;
656 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
659 sp->tx_delay = SIXP_TXDELAY;
660 sp->persistence = SIXP_PERSIST;
661 sp->slottime = SIXP_SLOTTIME;
662 sp->led_state = 0x60;
668 netif_start_queue(dev);
670 init_timer(&sp->tx_t);
671 sp->tx_t.function = sp_xmit_on_air;
672 sp->tx_t.data = (unsigned long) sp;
674 init_timer(&sp->resync_t);
676 spin_unlock_bh(&sp->lock);
678 /* Done. We have linked the TTY line to a channel. */
681 /* Now we're ready to register. */
682 if (register_netdev(dev))
702 * Close down a 6pack channel.
703 * This means flushing out any pending queues, and then restoring the
704 * TTY line discipline to what it was before it got hooked to 6pack
705 * (which usually is TTY again).
707 static void sixpack_close(struct tty_struct *tty)
711 write_lock(&disc_data_lock);
713 tty->disc_data = NULL;
714 write_unlock(&disc_data_lock);
719 * We have now ensured that nobody can start using ap from now on, but
720 * we have to wait for all existing users to finish.
722 if (!atomic_dec_and_test(&sp->refcnt))
725 unregister_netdev(sp->dev);
727 del_timer(&sp->tx_t);
728 del_timer(&sp->resync_t);
730 /* Free all 6pack frame buffers. */
735 /* Perform I/O control on an active 6pack channel. */
736 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
737 unsigned int cmd, unsigned long arg)
739 struct sixpack *sp = sp_get(tty);
740 struct net_device *dev = sp->dev;
741 unsigned int tmp, err;
748 err = copy_to_user((void __user *) arg, dev->name,
749 strlen(dev->name) + 1) ? -EFAULT : 0;
753 err = put_user(0, (int __user *) arg);
757 if (get_user(tmp, (int __user *) arg)) {
763 dev->addr_len = AX25_ADDR_LEN;
764 dev->hard_header_len = AX25_KISS_HEADER_LEN +
765 AX25_MAX_HEADER_LEN + 3;
766 dev->type = ARPHRD_AX25;
771 case SIOCSIFHWADDR: {
772 char addr[AX25_ADDR_LEN];
774 if (copy_from_user(&addr,
775 (void __user *) arg, AX25_ADDR_LEN)) {
780 spin_lock_irq(&dev->xmit_lock);
781 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
782 spin_unlock_irq(&dev->xmit_lock);
788 /* Allow stty to read, but not set, the serial port */
791 err = n_tty_ioctl(tty, (struct file *) file, cmd, arg);
803 static struct tty_ldisc sp_ldisc = {
804 .owner = THIS_MODULE,
805 .magic = TTY_LDISC_MAGIC,
807 .open = sixpack_open,
808 .close = sixpack_close,
809 .ioctl = sixpack_ioctl,
810 .receive_buf = sixpack_receive_buf,
811 .receive_room = sixpack_receive_room,
812 .write_wakeup = sixpack_write_wakeup,
815 /* Initialize 6pack control device -- register 6pack line discipline */
817 static char msg_banner[] __initdata = KERN_INFO \
818 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
819 static char msg_regfail[] __initdata = KERN_ERR \
820 "6pack: can't register line discipline (err = %d)\n";
822 static int __init sixpack_init_driver(void)
828 /* Register the provided line protocol discipline */
829 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
830 printk(msg_regfail, status);
835 static const char msg_unregfail[] __exitdata = KERN_ERR \
836 "6pack: can't unregister line discipline (err = %d)\n";
838 static void __exit sixpack_exit_driver(void)
842 if ((ret = tty_unregister_ldisc(N_6PACK)))
843 printk(msg_unregfail, ret);
846 /* encode an AX.25 packet into 6pack */
848 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
849 int length, unsigned char tx_delay)
852 unsigned char checksum = 0, buf[400];
855 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
856 tx_buf_raw[raw_count++] = SIXP_SEOF;
859 for (count = 1; count < length; count++)
860 buf[count] = tx_buf[count];
862 for (count = 0; count < length; count++)
863 checksum += buf[count];
864 buf[length] = (unsigned char) 0xff - checksum;
866 for (count = 0; count <= length; count++) {
867 if ((count % 3) == 0) {
868 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
869 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
870 } else if ((count % 3) == 1) {
871 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
872 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
874 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
875 tx_buf_raw[raw_count++] = (buf[count] >> 2);
878 if ((length % 3) != 2)
880 tx_buf_raw[raw_count++] = SIXP_SEOF;
884 /* decode 4 sixpack-encoded bytes into 3 data bytes */
886 static void decode_data(struct sixpack *sp, unsigned char inbyte)
890 if (sp->rx_count != 3) {
891 sp->raw_buf[sp->rx_count++] = inbyte;
897 sp->cooked_buf[sp->rx_count_cooked++] =
898 buf[0] | ((buf[1] << 2) & 0xc0);
899 sp->cooked_buf[sp->rx_count_cooked++] =
900 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
901 sp->cooked_buf[sp->rx_count_cooked++] =
902 (buf[2] & 0x03) | (inbyte << 2);
906 /* identify and execute a 6pack priority command byte */
908 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
910 unsigned char channel;
913 channel = cmd & SIXP_CHN_MASK;
914 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
916 /* RX and DCD flags can only be set in the same prio command,
917 if the DCD flag has been set without the RX flag in the previous
918 prio command. If DCD has not been set before, something in the
919 transmission has gone wrong. In this case, RX and DCD are
920 cleared in order to prevent the decode_data routine from
921 reading further data that might be corrupt. */
923 if (((sp->status & SIXP_DCD_MASK) == 0) &&
924 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
926 printk(KERN_DEBUG "6pack: protocol violation\n");
929 cmd &= !SIXP_RX_DCD_MASK;
931 sp->status = cmd & SIXP_PRIO_DATA_MASK;
932 } else { /* output watchdog char if idle */
933 if ((sp->status2 != 0) && (sp->duplex == 1)) {
934 sp->led_state = 0x70;
935 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
937 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
940 sp->led_state = 0x60;
946 /* needed to trigger the TNC watchdog */
947 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
949 /* if the state byte has been received, the TNC is present,
950 so the resync timer can be reset. */
952 if (sp->tnc_state == TNC_IN_SYNC) {
953 del_timer(&sp->resync_t);
954 sp->resync_t.data = (unsigned long) sp;
955 sp->resync_t.function = resync_tnc;
956 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
957 add_timer(&sp->resync_t);
960 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
963 /* identify and execute a standard 6pack command byte */
965 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
967 unsigned char checksum = 0, rest = 0, channel;
970 channel = cmd & SIXP_CHN_MASK;
971 switch (cmd & SIXP_CMD_MASK) { /* normal command */
973 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
974 if ((sp->status & SIXP_RX_DCD_MASK) ==
976 sp->led_state = 0x68;
977 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
980 sp->led_state = 0x60;
981 /* fill trailing bytes with zeroes */
982 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
985 for (i = rest; i <= 3; i++)
988 sp->rx_count_cooked -= 2;
990 sp->rx_count_cooked -= 1;
991 for (i = 0; i < sp->rx_count_cooked; i++)
992 checksum += sp->cooked_buf[i];
993 if (checksum != SIXP_CHKSUM) {
994 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
996 sp->rcount = sp->rx_count_cooked-2;
999 sp->rx_count_cooked = 0;
1002 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
1004 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
1006 case SIXP_RX_BUF_OVL:
1007 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
1011 /* decode a 6pack packet */
1014 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
1016 unsigned char inbyte;
1019 for (count1 = 0; count1 < count; count1++) {
1020 inbyte = pre_rbuff[count1];
1021 if (inbyte == SIXP_FOUND_TNC) {
1022 tnc_set_sync_state(sp, TNC_IN_SYNC);
1023 del_timer(&sp->resync_t);
1025 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1026 decode_prio_command(sp, inbyte);
1027 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1028 decode_std_command(sp, inbyte);
1029 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1030 decode_data(sp, inbyte);
1034 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1035 MODULE_DESCRIPTION("6pack driver for AX.25");
1036 MODULE_LICENSE("GPL");
1037 MODULE_ALIAS_LDISC(N_6PACK);
1039 module_init(sixpack_init_driver);
1040 module_exit(sixpack_exit_driver);