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 sp_start_tx_timer(struct sixpack *);
134 static void sixpack_decode(struct sixpack *, unsigned char[], int);
135 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
138 * perform the persistence/slottime algorithm for CSMA access. If the
139 * persistence check was successful, write the data to the serial driver.
140 * Note that in case of DAMA operation, the data is not sent here.
143 static void sp_xmit_on_air(unsigned long channel)
145 struct sixpack *sp = (struct sixpack *) channel;
147 static unsigned char random;
149 random = random * 17 + 41;
151 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
152 sp->led_state = 0x70;
153 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
155 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
158 sp->led_state = 0x60;
159 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
162 sp_start_tx_timer(sp);
165 /* ----> 6pack timer interrupt handler and friends. <---- */
166 static void sp_start_tx_timer(struct sixpack *sp)
168 int when = sp->slottime;
170 del_timer(&sp->tx_t);
171 sp->tx_t.data = (unsigned long) sp;
172 sp->tx_t.function = sp_xmit_on_air;
173 sp->tx_t.expires = jiffies + ((when + 1) * HZ) / 100;
174 add_timer(&sp->tx_t);
177 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */
178 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
180 unsigned char *msg, *p = icp;
183 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
184 msg = "oversized transmit packet!";
188 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
189 msg = "oversized transmit packet!";
194 msg = "invalid KISS command";
198 if ((p[0] != 0) && (len > 2)) {
199 msg = "KISS control packet too long";
203 if ((p[0] == 0) && (len < 15)) {
204 msg = "bad AX.25 packet to transmit";
208 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
209 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
212 case 1: sp->tx_delay = p[1];
214 case 2: sp->persistence = p[1];
216 case 3: sp->slottime = p[1];
218 case 4: /* ignored */
220 case 5: sp->duplex = p[1];
228 * In case of fullduplex or DAMA operation, we don't take care about the
229 * state of the DCD or of any timers, as the determination of the
230 * correct time to send is the job of the AX.25 layer. We send
231 * immediately after data has arrived.
233 if (sp->duplex == 1) {
234 sp->led_state = 0x70;
235 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
237 actual = sp->tty->driver->write(sp->tty, sp->xbuff, count);
238 sp->xleft = count - actual;
239 sp->xhead = sp->xbuff + actual;
240 sp->led_state = 0x60;
241 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
244 sp->xhead = sp->xbuff;
247 sp_start_tx_timer(sp);
253 sp->stats.tx_dropped++;
254 netif_start_queue(sp->dev);
256 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
259 /* Encapsulate an IP datagram and kick it into a TTY queue. */
261 static int sp_xmit(struct sk_buff *skb, struct net_device *dev)
263 struct sixpack *sp = netdev_priv(dev);
265 spin_lock_bh(&sp->lock);
266 /* We were not busy, so we are now... :-) */
267 netif_stop_queue(dev);
268 sp->stats.tx_bytes += skb->len;
269 sp_encaps(sp, skb->data, skb->len);
270 spin_unlock_bh(&sp->lock);
277 static int sp_open_dev(struct net_device *dev)
279 struct sixpack *sp = netdev_priv(dev);
286 /* Close the low-level part of the 6pack channel. */
287 static int sp_close(struct net_device *dev)
289 struct sixpack *sp = netdev_priv(dev);
291 spin_lock_bh(&sp->lock);
293 /* TTY discipline is running. */
294 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
296 netif_stop_queue(dev);
297 spin_unlock_bh(&sp->lock);
302 /* Return the frame type ID */
303 static int sp_header(struct sk_buff *skb, struct net_device *dev,
304 unsigned short type, void *daddr, void *saddr, unsigned len)
307 if (type != htons(ETH_P_AX25))
308 return ax25_encapsulate(skb, dev, type, daddr, saddr, len);
313 static struct net_device_stats *sp_get_stats(struct net_device *dev)
315 struct sixpack *sp = netdev_priv(dev);
319 static int sp_set_mac_address(struct net_device *dev, void *addr)
321 struct sockaddr_ax25 *sa = addr;
323 if (sa->sax25_family != AF_AX25)
326 if (!sa->sax25_ndigis)
329 spin_lock_irq(&dev->xmit_lock);
330 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
331 spin_unlock_irq(&dev->xmit_lock);
336 static int sp_rebuild_header(struct sk_buff *skb)
339 return ax25_rebuild_header(skb);
345 static void sp_setup(struct net_device *dev)
347 static char ax25_bcast[AX25_ADDR_LEN] =
348 {'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
349 static char ax25_test[AX25_ADDR_LEN] =
350 {'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};
352 /* Finish setting up the DEVICE info. */
354 dev->hard_start_xmit = sp_xmit;
355 dev->open = sp_open_dev;
356 dev->destructor = free_netdev;
357 dev->stop = sp_close;
358 dev->hard_header = sp_header;
359 dev->get_stats = sp_get_stats;
360 dev->set_mac_address = sp_set_mac_address;
361 dev->hard_header_len = AX25_MAX_HEADER_LEN;
362 dev->addr_len = AX25_ADDR_LEN;
363 dev->type = ARPHRD_AX25;
364 dev->tx_queue_len = 10;
365 dev->rebuild_header = sp_rebuild_header;
366 dev->tx_timeout = NULL;
368 /* Only activated in AX.25 mode */
369 memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);
370 memcpy(dev->dev_addr, ax25_test, AX25_ADDR_LEN);
372 SET_MODULE_OWNER(dev);
377 /* Send one completely decapsulated IP datagram to the IP layer. */
380 * This is the routine that sends the received data to the kernel AX.25.
381 * 'cmd' is the KISS command. For AX.25 data, it is zero.
384 static void sp_bump(struct sixpack *sp, char cmd)
390 count = sp->rcount + 1;
392 sp->stats.rx_bytes += count;
394 if ((skb = dev_alloc_skb(count)) == NULL)
398 ptr = skb_put(skb, count);
399 *ptr++ = cmd; /* KISS command */
401 memcpy(ptr, sp->cooked_buf + 1, count);
402 skb->mac.raw = skb->data;
403 skb->protocol = htons(ETH_P_AX25);
405 sp->dev->last_rx = jiffies;
406 sp->stats.rx_packets++;
411 sp->stats.rx_dropped++;
415 /* ----------------------------------------------------------------------- */
418 * We have a potential race on dereferencing tty->disc_data, because the tty
419 * layer provides no locking at all - thus one cpu could be running
420 * sixpack_receive_buf while another calls sixpack_close, which zeroes
421 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
422 * best way to fix this is to use a rwlock in the tty struct, but for now we
423 * use a single global rwlock for all ttys in ppp line discipline.
425 static DEFINE_RWLOCK(disc_data_lock);
427 static struct sixpack *sp_get(struct tty_struct *tty)
431 read_lock(&disc_data_lock);
434 atomic_inc(&sp->refcnt);
435 read_unlock(&disc_data_lock);
440 static void sp_put(struct sixpack *sp)
442 if (atomic_dec_and_test(&sp->refcnt))
447 * Called by the TTY driver when there's room for more data. If we have
448 * more packets to send, we send them here.
450 static void sixpack_write_wakeup(struct tty_struct *tty)
452 struct sixpack *sp = sp_get(tty);
457 if (sp->xleft <= 0) {
458 /* Now serial buffer is almost free & we can start
459 * transmission of another packet */
460 sp->stats.tx_packets++;
461 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
463 netif_wake_queue(sp->dev);
468 actual = tty->driver->write(tty, sp->xhead, sp->xleft);
477 /* ----------------------------------------------------------------------- */
479 static int sixpack_receive_room(struct tty_struct *tty)
481 return 65536; /* We can handle an infinite amount of data. :-) */
485 * Handle the 'receiver data ready' interrupt.
486 * This function is called by the 'tty_io' module in the kernel when
487 * a block of 6pack data has been received, which can now be decapsulated
488 * and sent on to some IP layer for further processing.
490 static void sixpack_receive_buf(struct tty_struct *tty,
491 const unsigned char *cp, char *fp, int count)
494 unsigned char buf[512];
504 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
506 /* Read the characters out of the buffer */
512 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
513 sp->stats.rx_errors++;
517 sixpack_decode(sp, buf, count1);
520 if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
521 && tty->driver->unthrottle)
522 tty->driver->unthrottle(tty);
526 * Try to resync the TNC. Called by the resync timer defined in
527 * decode_prio_command
530 #define TNC_UNINITIALIZED 0
531 #define TNC_UNSYNC_STARTUP 1
532 #define TNC_UNSYNCED 2
533 #define TNC_IN_SYNC 3
535 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
539 switch (new_tnc_state) {
540 default: /* gcc oh piece-o-crap ... */
541 case TNC_UNSYNC_STARTUP:
542 msg = "Synchronizing with TNC";
545 msg = "Lost synchronization with TNC\n";
552 sp->tnc_state = new_tnc_state;
553 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
556 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
558 int old_tnc_state = sp->tnc_state;
560 if (old_tnc_state != new_tnc_state)
561 __tnc_set_sync_state(sp, new_tnc_state);
564 static void resync_tnc(unsigned long channel)
566 struct sixpack *sp = (struct sixpack *) channel;
567 static char resync_cmd = 0xe8;
569 /* clear any data that might have been received */
572 sp->rx_count_cooked = 0;
574 /* reset state machine */
582 sp->led_state = 0x60;
583 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
584 sp->tty->driver->write(sp->tty, &resync_cmd, 1);
587 /* Start resync timer again -- the TNC might be still absent */
589 del_timer(&sp->resync_t);
590 sp->resync_t.data = (unsigned long) sp;
591 sp->resync_t.function = resync_tnc;
592 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
593 add_timer(&sp->resync_t);
596 static inline int tnc_init(struct sixpack *sp)
598 unsigned char inbyte = 0xe8;
600 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
602 sp->tty->driver->write(sp->tty, &inbyte, 1);
604 del_timer(&sp->resync_t);
605 sp->resync_t.data = (unsigned long) sp;
606 sp->resync_t.function = resync_tnc;
607 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
608 add_timer(&sp->resync_t);
614 * Open the high-level part of the 6pack channel.
615 * This function is called by the TTY module when the
616 * 6pack line discipline is called for. Because we are
617 * sure the tty line exists, we only have to link it to
618 * a free 6pcack channel...
620 static int sixpack_open(struct tty_struct *tty)
622 char *rbuff = NULL, *xbuff = NULL;
623 struct net_device *dev;
628 if (!capable(CAP_NET_ADMIN))
631 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
637 sp = netdev_priv(dev);
640 spin_lock_init(&sp->lock);
641 atomic_set(&sp->refcnt, 1);
642 init_MUTEX_LOCKED(&sp->dead_sem);
644 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
648 rbuff = kmalloc(len + 4, GFP_KERNEL);
649 xbuff = kmalloc(len + 4, GFP_KERNEL);
651 if (rbuff == NULL || xbuff == NULL) {
656 spin_lock_bh(&sp->lock);
663 sp->mtu = AX25_MTU + 73;
667 sp->rx_count_cooked = 0;
670 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
673 sp->tx_delay = SIXP_TXDELAY;
674 sp->persistence = SIXP_PERSIST;
675 sp->slottime = SIXP_SLOTTIME;
676 sp->led_state = 0x60;
682 netif_start_queue(dev);
684 init_timer(&sp->tx_t);
685 init_timer(&sp->resync_t);
687 spin_unlock_bh(&sp->lock);
689 /* Done. We have linked the TTY line to a channel. */
692 /* Now we're ready to register. */
693 if (register_netdev(dev))
713 * Close down a 6pack channel.
714 * This means flushing out any pending queues, and then restoring the
715 * TTY line discipline to what it was before it got hooked to 6pack
716 * (which usually is TTY again).
718 static void sixpack_close(struct tty_struct *tty)
722 write_lock(&disc_data_lock);
724 tty->disc_data = NULL;
725 write_unlock(&disc_data_lock);
730 * We have now ensured that nobody can start using ap from now on, but
731 * we have to wait for all existing users to finish.
733 if (!atomic_dec_and_test(&sp->refcnt))
736 unregister_netdev(sp->dev);
738 del_timer(&sp->tx_t);
739 del_timer(&sp->resync_t);
741 /* Free all 6pack frame buffers. */
746 /* Perform I/O control on an active 6pack channel. */
747 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
748 unsigned int cmd, unsigned long arg)
750 struct sixpack *sp = sp_get(tty);
751 struct net_device *dev = sp->dev;
752 unsigned int tmp, err;
759 err = copy_to_user((void *) arg, dev->name,
760 strlen(dev->name) + 1) ? -EFAULT : 0;
764 err = put_user(0, (int __user *)arg);
768 if (get_user(tmp, (int __user *) arg)) {
774 dev->addr_len = AX25_ADDR_LEN;
775 dev->hard_header_len = AX25_KISS_HEADER_LEN +
776 AX25_MAX_HEADER_LEN + 3;
777 dev->type = ARPHRD_AX25;
782 case SIOCSIFHWADDR: {
783 char addr[AX25_ADDR_LEN];
785 if (copy_from_user(&addr,
786 (void __user *) arg, AX25_ADDR_LEN)) {
791 spin_lock_irq(&dev->xmit_lock);
792 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
793 spin_unlock_irq(&dev->xmit_lock);
799 /* Allow stty to read, but not set, the serial port */
802 err = n_tty_ioctl(tty, (struct file *) file, cmd, arg);
814 static struct tty_ldisc sp_ldisc = {
815 .owner = THIS_MODULE,
816 .magic = TTY_LDISC_MAGIC,
818 .open = sixpack_open,
819 .close = sixpack_close,
820 .ioctl = sixpack_ioctl,
821 .receive_buf = sixpack_receive_buf,
822 .receive_room = sixpack_receive_room,
823 .write_wakeup = sixpack_write_wakeup,
826 /* Initialize 6pack control device -- register 6pack line discipline */
828 static char msg_banner[] __initdata = KERN_INFO \
829 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
830 static char msg_regfail[] __initdata = KERN_ERR \
831 "6pack: can't register line discipline (err = %d)\n";
833 static int __init sixpack_init_driver(void)
839 /* Register the provided line protocol discipline */
840 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
841 printk(msg_regfail, status);
846 static const char msg_unregfail[] __exitdata = KERN_ERR \
847 "6pack: can't unregister line discipline (err = %d)\n";
849 static void __exit sixpack_exit_driver(void)
853 if ((ret = tty_register_ldisc(N_6PACK, NULL)))
854 printk(msg_unregfail, ret);
857 /* encode an AX.25 packet into 6pack */
859 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
860 int length, unsigned char tx_delay)
863 unsigned char checksum = 0, buf[400];
866 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
867 tx_buf_raw[raw_count++] = SIXP_SEOF;
870 for (count = 1; count < length; count++)
871 buf[count] = tx_buf[count];
873 for (count = 0; count < length; count++)
874 checksum += buf[count];
875 buf[length] = (unsigned char) 0xff - checksum;
877 for (count = 0; count <= length; count++) {
878 if ((count % 3) == 0) {
879 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
880 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
881 } else if ((count % 3) == 1) {
882 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
883 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
885 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
886 tx_buf_raw[raw_count++] = (buf[count] >> 2);
889 if ((length % 3) != 2)
891 tx_buf_raw[raw_count++] = SIXP_SEOF;
895 /* decode 4 sixpack-encoded bytes into 3 data bytes */
897 static void decode_data(struct sixpack *sp, unsigned char inbyte)
901 if (sp->rx_count != 3) {
902 sp->raw_buf[sp->rx_count++] = inbyte;
908 sp->cooked_buf[sp->rx_count_cooked++] =
909 buf[0] | ((buf[1] << 2) & 0xc0);
910 sp->cooked_buf[sp->rx_count_cooked++] =
911 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
912 sp->cooked_buf[sp->rx_count_cooked++] =
913 (buf[2] & 0x03) | (inbyte << 2);
917 /* identify and execute a 6pack priority command byte */
919 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
921 unsigned char channel;
924 channel = cmd & SIXP_CHN_MASK;
925 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
927 /* RX and DCD flags can only be set in the same prio command,
928 if the DCD flag has been set without the RX flag in the previous
929 prio command. If DCD has not been set before, something in the
930 transmission has gone wrong. In this case, RX and DCD are
931 cleared in order to prevent the decode_data routine from
932 reading further data that might be corrupt. */
934 if (((sp->status & SIXP_DCD_MASK) == 0) &&
935 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
937 printk(KERN_DEBUG "6pack: protocol violation\n");
940 cmd &= !SIXP_RX_DCD_MASK;
942 sp->status = cmd & SIXP_PRIO_DATA_MASK;
943 } else { /* output watchdog char if idle */
944 if ((sp->status2 != 0) && (sp->duplex == 1)) {
945 sp->led_state = 0x70;
946 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
948 actual = sp->tty->driver->write(sp->tty, sp->xbuff, sp->status2);
951 sp->led_state = 0x60;
957 /* needed to trigger the TNC watchdog */
958 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
960 /* if the state byte has been received, the TNC is present,
961 so the resync timer can be reset. */
963 if (sp->tnc_state == TNC_IN_SYNC) {
964 del_timer(&sp->resync_t);
965 sp->resync_t.data = (unsigned long) sp;
966 sp->resync_t.function = resync_tnc;
967 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
968 add_timer(&sp->resync_t);
971 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
974 /* identify and execute a standard 6pack command byte */
976 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
978 unsigned char checksum = 0, rest = 0, channel;
981 channel = cmd & SIXP_CHN_MASK;
982 switch (cmd & SIXP_CMD_MASK) { /* normal command */
984 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
985 if ((sp->status & SIXP_RX_DCD_MASK) ==
987 sp->led_state = 0x68;
988 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
991 sp->led_state = 0x60;
992 /* fill trailing bytes with zeroes */
993 sp->tty->driver->write(sp->tty, &sp->led_state, 1);
996 for (i = rest; i <= 3; i++)
999 sp->rx_count_cooked -= 2;
1001 sp->rx_count_cooked -= 1;
1002 for (i = 0; i < sp->rx_count_cooked; i++)
1003 checksum += sp->cooked_buf[i];
1004 if (checksum != SIXP_CHKSUM) {
1005 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
1007 sp->rcount = sp->rx_count_cooked-2;
1010 sp->rx_count_cooked = 0;
1013 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
1015 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
1017 case SIXP_RX_BUF_OVL:
1018 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
1022 /* decode a 6pack packet */
1025 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
1027 unsigned char inbyte;
1030 for (count1 = 0; count1 < count; count1++) {
1031 inbyte = pre_rbuff[count1];
1032 if (inbyte == SIXP_FOUND_TNC) {
1033 tnc_set_sync_state(sp, TNC_IN_SYNC);
1034 del_timer(&sp->resync_t);
1036 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1037 decode_prio_command(sp, inbyte);
1038 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1039 decode_std_command(sp, inbyte);
1040 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1041 decode_data(sp, inbyte);
1045 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1046 MODULE_DESCRIPTION("6pack driver for AX.25");
1047 MODULE_LICENSE("GPL");
1048 MODULE_ALIAS_LDISC(N_6PACK);
1050 module_init(sixpack_init_driver);
1051 module_exit(sixpack_exit_driver);