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/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 <linux/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 int mtu; /* Our mtu (to spot changes!) */
103 int buffsize; /* Max buffers sizes */
105 unsigned long flags; /* Flag values/ mode etc */
106 unsigned char mode; /* 6pack mode */
109 unsigned char tx_delay;
110 unsigned char persistence;
111 unsigned char slottime;
112 unsigned char duplex;
113 unsigned char led_state;
114 unsigned char status;
115 unsigned char status1;
116 unsigned char status2;
117 unsigned char tx_enable;
118 unsigned char tnc_state;
120 struct timer_list tx_t;
121 struct timer_list resync_t;
123 struct semaphore dead_sem;
127 #define AX25_6PACK_HEADER_LEN 0
129 static void sixpack_decode(struct sixpack *, unsigned char[], int);
130 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
133 * Perform the persistence/slottime algorithm for CSMA access. If the
134 * persistence check was successful, write the data to the serial driver.
135 * Note that in case of DAMA operation, the data is not sent here.
138 static void sp_xmit_on_air(unsigned long channel)
140 struct sixpack *sp = (struct sixpack *) channel;
141 int actual, when = sp->slottime;
142 static unsigned char random;
144 random = random * 17 + 41;
146 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
147 sp->led_state = 0x70;
148 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
150 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
153 sp->led_state = 0x60;
154 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
157 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
160 /* ----> 6pack timer interrupt handler and friends. <---- */
162 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */
163 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
165 unsigned char *msg, *p = icp;
168 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
169 msg = "oversized transmit packet!";
173 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
174 msg = "oversized transmit packet!";
179 msg = "invalid KISS command";
183 if ((p[0] != 0) && (len > 2)) {
184 msg = "KISS control packet too long";
188 if ((p[0] == 0) && (len < 15)) {
189 msg = "bad AX.25 packet to transmit";
193 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
194 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
197 case 1: sp->tx_delay = p[1];
199 case 2: sp->persistence = p[1];
201 case 3: sp->slottime = p[1];
203 case 4: /* ignored */
205 case 5: sp->duplex = p[1];
213 * In case of fullduplex or DAMA operation, we don't take care about the
214 * state of the DCD or of any timers, as the determination of the
215 * correct time to send is the job of the AX.25 layer. We send
216 * immediately after data has arrived.
218 if (sp->duplex == 1) {
219 sp->led_state = 0x70;
220 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
222 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
223 sp->xleft = count - actual;
224 sp->xhead = sp->xbuff + actual;
225 sp->led_state = 0x60;
226 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
229 sp->xhead = sp->xbuff;
231 sp_xmit_on_air((unsigned long)sp);
237 sp->dev->stats.tx_dropped++;
238 netif_start_queue(sp->dev);
240 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
243 /* Encapsulate an IP datagram and kick it into a TTY queue. */
245 static int sp_xmit(struct sk_buff *skb, struct net_device *dev)
247 struct sixpack *sp = netdev_priv(dev);
249 spin_lock_bh(&sp->lock);
250 /* We were not busy, so we are now... :-) */
251 netif_stop_queue(dev);
252 dev->stats.tx_bytes += skb->len;
253 sp_encaps(sp, skb->data, skb->len);
254 spin_unlock_bh(&sp->lock);
261 static int sp_open_dev(struct net_device *dev)
263 struct sixpack *sp = netdev_priv(dev);
270 /* Close the low-level part of the 6pack channel. */
271 static int sp_close(struct net_device *dev)
273 struct sixpack *sp = netdev_priv(dev);
275 spin_lock_bh(&sp->lock);
277 /* TTY discipline is running. */
278 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
280 netif_stop_queue(dev);
281 spin_unlock_bh(&sp->lock);
286 /* Return the frame type ID */
287 static int sp_header(struct sk_buff *skb, struct net_device *dev,
288 unsigned short type, const void *daddr,
289 const void *saddr, unsigned len)
292 if (type != ETH_P_AX25)
293 return ax25_hard_header(skb, dev, type, daddr, saddr, len);
298 static int sp_set_mac_address(struct net_device *dev, void *addr)
300 struct sockaddr_ax25 *sa = addr;
302 netif_tx_lock_bh(dev);
303 netif_addr_lock(dev);
304 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
305 netif_addr_unlock(dev);
306 netif_tx_unlock_bh(dev);
311 static int sp_rebuild_header(struct sk_buff *skb)
314 return ax25_rebuild_header(skb);
320 static const struct header_ops sp_header_ops = {
322 .rebuild = sp_rebuild_header,
325 static const struct net_device_ops sp_netdev_ops = {
326 .ndo_open = sp_open_dev,
327 .ndo_stop = sp_close,
328 .ndo_start_xmit = sp_xmit,
329 .ndo_set_mac_address = sp_set_mac_address,
332 static void sp_setup(struct net_device *dev)
334 /* Finish setting up the DEVICE info. */
335 dev->netdev_ops = &sp_netdev_ops;
336 dev->destructor = free_netdev;
338 dev->hard_header_len = AX25_MAX_HEADER_LEN;
339 dev->header_ops = &sp_header_ops;
341 dev->addr_len = AX25_ADDR_LEN;
342 dev->type = ARPHRD_AX25;
343 dev->tx_queue_len = 10;
345 /* Only activated in AX.25 mode */
346 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
347 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
352 /* Send one completely decapsulated IP datagram to the IP layer. */
355 * This is the routine that sends the received data to the kernel AX.25.
356 * 'cmd' is the KISS command. For AX.25 data, it is zero.
359 static void sp_bump(struct sixpack *sp, char cmd)
365 count = sp->rcount + 1;
367 sp->dev->stats.rx_bytes += count;
369 if ((skb = dev_alloc_skb(count)) == NULL)
372 ptr = skb_put(skb, count);
373 *ptr++ = cmd; /* KISS command */
375 memcpy(ptr, sp->cooked_buf + 1, count);
376 skb->protocol = ax25_type_trans(skb, sp->dev);
378 sp->dev->stats.rx_packets++;
383 sp->dev->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)
404 read_lock_irqsave(&disc_data_lock, flags);
407 atomic_inc(&sp->refcnt);
408 read_unlock_irqrestore(&disc_data_lock, flags);
413 static void sp_put(struct sixpack *sp)
415 if (atomic_dec_and_test(&sp->refcnt))
420 * Called by the TTY driver when there's room for more data. If we have
421 * more packets to send, we send them here.
423 static void sixpack_write_wakeup(struct tty_struct *tty)
425 struct sixpack *sp = sp_get(tty);
430 if (sp->xleft <= 0) {
431 /* Now serial buffer is almost free & we can start
432 * transmission of another packet */
433 sp->dev->stats.tx_packets++;
434 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
436 netif_wake_queue(sp->dev);
441 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
450 /* ----------------------------------------------------------------------- */
453 * Handle the 'receiver data ready' interrupt.
454 * This function is called by the 'tty_io' module in the kernel when
455 * a block of 6pack data has been received, which can now be decapsulated
456 * and sent on to some IP layer for further processing.
458 static void sixpack_receive_buf(struct tty_struct *tty,
459 const unsigned char *cp, char *fp, int count)
462 unsigned char buf[512];
472 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
474 /* Read the characters out of the buffer */
480 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
481 sp->dev->stats.rx_errors++;
485 sixpack_decode(sp, buf, count1);
492 * Try to resync the TNC. Called by the resync timer defined in
493 * decode_prio_command
496 #define TNC_UNINITIALIZED 0
497 #define TNC_UNSYNC_STARTUP 1
498 #define TNC_UNSYNCED 2
499 #define TNC_IN_SYNC 3
501 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
505 switch (new_tnc_state) {
506 default: /* gcc oh piece-o-crap ... */
507 case TNC_UNSYNC_STARTUP:
508 msg = "Synchronizing with TNC";
511 msg = "Lost synchronization with TNC\n";
518 sp->tnc_state = new_tnc_state;
519 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
522 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
524 int old_tnc_state = sp->tnc_state;
526 if (old_tnc_state != new_tnc_state)
527 __tnc_set_sync_state(sp, new_tnc_state);
530 static void resync_tnc(unsigned long channel)
532 struct sixpack *sp = (struct sixpack *) channel;
533 static char resync_cmd = 0xe8;
535 /* clear any data that might have been received */
538 sp->rx_count_cooked = 0;
540 /* reset state machine */
548 sp->led_state = 0x60;
549 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
550 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
553 /* Start resync timer again -- the TNC might be still absent */
555 del_timer(&sp->resync_t);
556 sp->resync_t.data = (unsigned long) sp;
557 sp->resync_t.function = resync_tnc;
558 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
559 add_timer(&sp->resync_t);
562 static inline int tnc_init(struct sixpack *sp)
564 unsigned char inbyte = 0xe8;
566 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
568 sp->tty->ops->write(sp->tty, &inbyte, 1);
570 del_timer(&sp->resync_t);
571 sp->resync_t.data = (unsigned long) sp;
572 sp->resync_t.function = resync_tnc;
573 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
574 add_timer(&sp->resync_t);
580 * Open the high-level part of the 6pack channel.
581 * This function is called by the TTY module when the
582 * 6pack line discipline is called for. Because we are
583 * sure the tty line exists, we only have to link it to
584 * a free 6pcack channel...
586 static int sixpack_open(struct tty_struct *tty)
588 char *rbuff = NULL, *xbuff = NULL;
589 struct net_device *dev;
594 if (!capable(CAP_NET_ADMIN))
596 if (tty->ops->write == NULL)
599 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
605 sp = netdev_priv(dev);
608 spin_lock_init(&sp->lock);
609 atomic_set(&sp->refcnt, 1);
610 init_MUTEX_LOCKED(&sp->dead_sem);
612 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
616 rbuff = kmalloc(len + 4, GFP_KERNEL);
617 xbuff = kmalloc(len + 4, GFP_KERNEL);
619 if (rbuff == NULL || xbuff == NULL) {
624 spin_lock_bh(&sp->lock);
631 sp->mtu = AX25_MTU + 73;
635 sp->rx_count_cooked = 0;
638 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
641 sp->tx_delay = SIXP_TXDELAY;
642 sp->persistence = SIXP_PERSIST;
643 sp->slottime = SIXP_SLOTTIME;
644 sp->led_state = 0x60;
650 netif_start_queue(dev);
652 init_timer(&sp->tx_t);
653 sp->tx_t.function = sp_xmit_on_air;
654 sp->tx_t.data = (unsigned long) sp;
656 init_timer(&sp->resync_t);
658 spin_unlock_bh(&sp->lock);
660 /* Done. We have linked the TTY line to a channel. */
662 tty->receive_room = 65536;
664 /* Now we're ready to register. */
665 if (register_netdev(dev))
685 * Close down a 6pack channel.
686 * This means flushing out any pending queues, and then restoring the
687 * TTY line discipline to what it was before it got hooked to 6pack
688 * (which usually is TTY again).
690 static void sixpack_close(struct tty_struct *tty)
695 write_lock_irqsave(&disc_data_lock, flags);
697 tty->disc_data = NULL;
698 write_unlock_irqrestore(&disc_data_lock, flags);
703 * We have now ensured that nobody can start using ap from now on, but
704 * we have to wait for all existing users to finish.
706 if (!atomic_dec_and_test(&sp->refcnt))
709 unregister_netdev(sp->dev);
711 del_timer(&sp->tx_t);
712 del_timer(&sp->resync_t);
714 /* Free all 6pack frame buffers. */
719 /* Perform I/O control on an active 6pack channel. */
720 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
721 unsigned int cmd, unsigned long arg)
723 struct sixpack *sp = sp_get(tty);
724 struct net_device *dev;
725 unsigned int tmp, err;
733 err = copy_to_user((void __user *) arg, dev->name,
734 strlen(dev->name) + 1) ? -EFAULT : 0;
738 err = put_user(0, (int __user *) arg);
742 if (get_user(tmp, (int __user *) arg)) {
748 dev->addr_len = AX25_ADDR_LEN;
749 dev->hard_header_len = AX25_KISS_HEADER_LEN +
750 AX25_MAX_HEADER_LEN + 3;
751 dev->type = ARPHRD_AX25;
756 case SIOCSIFHWADDR: {
757 char addr[AX25_ADDR_LEN];
759 if (copy_from_user(&addr,
760 (void __user *) arg, AX25_ADDR_LEN)) {
765 netif_tx_lock_bh(dev);
766 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
767 netif_tx_unlock_bh(dev);
774 err = tty_mode_ioctl(tty, file, cmd, arg);
782 static struct tty_ldisc_ops sp_ldisc = {
783 .owner = THIS_MODULE,
784 .magic = TTY_LDISC_MAGIC,
786 .open = sixpack_open,
787 .close = sixpack_close,
788 .ioctl = sixpack_ioctl,
789 .receive_buf = sixpack_receive_buf,
790 .write_wakeup = sixpack_write_wakeup,
793 /* Initialize 6pack control device -- register 6pack line discipline */
795 static const char msg_banner[] __initdata = KERN_INFO \
796 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
797 static const char msg_regfail[] __initdata = KERN_ERR \
798 "6pack: can't register line discipline (err = %d)\n";
800 static int __init sixpack_init_driver(void)
806 /* Register the provided line protocol discipline */
807 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
808 printk(msg_regfail, status);
813 static const char msg_unregfail[] __exitdata = KERN_ERR \
814 "6pack: can't unregister line discipline (err = %d)\n";
816 static void __exit sixpack_exit_driver(void)
820 if ((ret = tty_unregister_ldisc(N_6PACK)))
821 printk(msg_unregfail, ret);
824 /* encode an AX.25 packet into 6pack */
826 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
827 int length, unsigned char tx_delay)
830 unsigned char checksum = 0, buf[400];
833 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
834 tx_buf_raw[raw_count++] = SIXP_SEOF;
837 for (count = 1; count < length; count++)
838 buf[count] = tx_buf[count];
840 for (count = 0; count < length; count++)
841 checksum += buf[count];
842 buf[length] = (unsigned char) 0xff - checksum;
844 for (count = 0; count <= length; count++) {
845 if ((count % 3) == 0) {
846 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
847 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
848 } else if ((count % 3) == 1) {
849 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
850 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
852 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
853 tx_buf_raw[raw_count++] = (buf[count] >> 2);
856 if ((length % 3) != 2)
858 tx_buf_raw[raw_count++] = SIXP_SEOF;
862 /* decode 4 sixpack-encoded bytes into 3 data bytes */
864 static void decode_data(struct sixpack *sp, unsigned char inbyte)
868 if (sp->rx_count != 3) {
869 sp->raw_buf[sp->rx_count++] = inbyte;
875 sp->cooked_buf[sp->rx_count_cooked++] =
876 buf[0] | ((buf[1] << 2) & 0xc0);
877 sp->cooked_buf[sp->rx_count_cooked++] =
878 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
879 sp->cooked_buf[sp->rx_count_cooked++] =
880 (buf[2] & 0x03) | (inbyte << 2);
884 /* identify and execute a 6pack priority command byte */
886 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
888 unsigned char channel;
891 channel = cmd & SIXP_CHN_MASK;
892 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
894 /* RX and DCD flags can only be set in the same prio command,
895 if the DCD flag has been set without the RX flag in the previous
896 prio command. If DCD has not been set before, something in the
897 transmission has gone wrong. In this case, RX and DCD are
898 cleared in order to prevent the decode_data routine from
899 reading further data that might be corrupt. */
901 if (((sp->status & SIXP_DCD_MASK) == 0) &&
902 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
904 printk(KERN_DEBUG "6pack: protocol violation\n");
907 cmd &= ~SIXP_RX_DCD_MASK;
909 sp->status = cmd & SIXP_PRIO_DATA_MASK;
910 } else { /* output watchdog char if idle */
911 if ((sp->status2 != 0) && (sp->duplex == 1)) {
912 sp->led_state = 0x70;
913 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
915 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
918 sp->led_state = 0x60;
924 /* needed to trigger the TNC watchdog */
925 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
927 /* if the state byte has been received, the TNC is present,
928 so the resync timer can be reset. */
930 if (sp->tnc_state == TNC_IN_SYNC) {
931 del_timer(&sp->resync_t);
932 sp->resync_t.data = (unsigned long) sp;
933 sp->resync_t.function = resync_tnc;
934 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
935 add_timer(&sp->resync_t);
938 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
941 /* identify and execute a standard 6pack command byte */
943 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
945 unsigned char checksum = 0, rest = 0, channel;
948 channel = cmd & SIXP_CHN_MASK;
949 switch (cmd & SIXP_CMD_MASK) { /* normal command */
951 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
952 if ((sp->status & SIXP_RX_DCD_MASK) ==
954 sp->led_state = 0x68;
955 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
958 sp->led_state = 0x60;
959 /* fill trailing bytes with zeroes */
960 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
963 for (i = rest; i <= 3; i++)
966 sp->rx_count_cooked -= 2;
968 sp->rx_count_cooked -= 1;
969 for (i = 0; i < sp->rx_count_cooked; i++)
970 checksum += sp->cooked_buf[i];
971 if (checksum != SIXP_CHKSUM) {
972 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
974 sp->rcount = sp->rx_count_cooked-2;
977 sp->rx_count_cooked = 0;
980 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
982 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
984 case SIXP_RX_BUF_OVL:
985 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
989 /* decode a 6pack packet */
992 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
994 unsigned char inbyte;
997 for (count1 = 0; count1 < count; count1++) {
998 inbyte = pre_rbuff[count1];
999 if (inbyte == SIXP_FOUND_TNC) {
1000 tnc_set_sync_state(sp, TNC_IN_SYNC);
1001 del_timer(&sp->resync_t);
1003 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1004 decode_prio_command(sp, inbyte);
1005 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1006 decode_std_command(sp, inbyte);
1007 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1008 decode_data(sp, inbyte);
1012 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1013 MODULE_DESCRIPTION("6pack driver for AX.25");
1014 MODULE_LICENSE("GPL");
1015 MODULE_ALIAS_LDISC(N_6PACK);
1017 module_init(sixpack_init_driver);
1018 module_exit(sixpack_exit_driver);