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@comnets.uni-bremen.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>
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/compat.h>
39 #include <asm/atomic.h>
41 #define SIXPACK_VERSION "Revision: 0.3.0"
43 /* sixpack priority commands */
44 #define SIXP_SEOF 0x40 /* start and end of a 6pack frame */
45 #define SIXP_TX_URUN 0x48 /* transmit overrun */
46 #define SIXP_RX_ORUN 0x50 /* receive overrun */
47 #define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */
49 #define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
51 /* masks to get certain bits out of the status bytes sent by the TNC */
53 #define SIXP_CMD_MASK 0xC0
54 #define SIXP_CHN_MASK 0x07
55 #define SIXP_PRIO_CMD_MASK 0x80
56 #define SIXP_STD_CMD_MASK 0x40
57 #define SIXP_PRIO_DATA_MASK 0x38
58 #define SIXP_TX_MASK 0x20
59 #define SIXP_RX_MASK 0x10
60 #define SIXP_RX_DCD_MASK 0x18
61 #define SIXP_LEDS_ON 0x78
62 #define SIXP_LEDS_OFF 0x60
66 #define SIXP_FOUND_TNC 0xe9
67 #define SIXP_CON_ON 0x68
68 #define SIXP_DCD_MASK 0x08
69 #define SIXP_DAMA_OFF 0
71 /* default level 2 parameters */
72 #define SIXP_TXDELAY (HZ/4) /* in 1 s */
73 #define SIXP_PERSIST 50 /* in 256ths */
74 #define SIXP_SLOTTIME (HZ/10) /* in 1 s */
75 #define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */
76 #define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */
78 /* 6pack configuration. */
79 #define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
80 #define SIXP_MTU 256 /* Default MTU */
83 SIXPF_ERROR, /* Parity, etc. error */
88 struct tty_struct *tty; /* ptr to TTY structure */
89 struct net_device *dev; /* easy for intr handling */
91 /* These are pointers to the malloc()ed frame buffers. */
92 unsigned char *rbuff; /* receiver buffer */
93 int rcount; /* received chars counter */
94 unsigned char *xbuff; /* transmitter buffer */
95 unsigned char *xhead; /* next byte to XMIT */
96 int xleft; /* bytes left in XMIT queue */
98 unsigned char raw_buf[4];
99 unsigned char cooked_buf[400];
101 unsigned int rx_count;
102 unsigned int rx_count_cooked;
104 int mtu; /* Our mtu (to spot changes!) */
105 int buffsize; /* Max buffers sizes */
107 unsigned long flags; /* Flag values/ mode etc */
108 unsigned char mode; /* 6pack mode */
111 unsigned char tx_delay;
112 unsigned char persistence;
113 unsigned char slottime;
114 unsigned char duplex;
115 unsigned char led_state;
116 unsigned char status;
117 unsigned char status1;
118 unsigned char status2;
119 unsigned char tx_enable;
120 unsigned char tnc_state;
122 struct timer_list tx_t;
123 struct timer_list resync_t;
125 struct semaphore dead_sem;
129 #define AX25_6PACK_HEADER_LEN 0
131 static void sixpack_decode(struct sixpack *, unsigned char[], int);
132 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
135 * Perform the persistence/slottime algorithm for CSMA access. If the
136 * persistence check was successful, write the data to the serial driver.
137 * Note that in case of DAMA operation, the data is not sent here.
140 static void sp_xmit_on_air(unsigned long channel)
142 struct sixpack *sp = (struct sixpack *) channel;
143 int actual, when = sp->slottime;
144 static unsigned char random;
146 random = random * 17 + 41;
148 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
149 sp->led_state = 0x70;
150 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
152 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
155 sp->led_state = 0x60;
156 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
159 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
162 /* ----> 6pack timer interrupt handler and friends. <---- */
164 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */
165 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
167 unsigned char *msg, *p = icp;
170 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
171 msg = "oversized transmit packet!";
175 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
176 msg = "oversized transmit packet!";
181 msg = "invalid KISS command";
185 if ((p[0] != 0) && (len > 2)) {
186 msg = "KISS control packet too long";
190 if ((p[0] == 0) && (len < 15)) {
191 msg = "bad AX.25 packet to transmit";
195 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
196 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
199 case 1: sp->tx_delay = p[1];
201 case 2: sp->persistence = p[1];
203 case 3: sp->slottime = p[1];
205 case 4: /* ignored */
207 case 5: sp->duplex = p[1];
215 * In case of fullduplex or DAMA operation, we don't take care about the
216 * state of the DCD or of any timers, as the determination of the
217 * correct time to send is the job of the AX.25 layer. We send
218 * immediately after data has arrived.
220 if (sp->duplex == 1) {
221 sp->led_state = 0x70;
222 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
224 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
225 sp->xleft = count - actual;
226 sp->xhead = sp->xbuff + actual;
227 sp->led_state = 0x60;
228 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
231 sp->xhead = sp->xbuff;
233 sp_xmit_on_air((unsigned long)sp);
239 sp->dev->stats.tx_dropped++;
240 netif_start_queue(sp->dev);
242 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
245 /* Encapsulate an IP datagram and kick it into a TTY queue. */
247 static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
249 struct sixpack *sp = netdev_priv(dev);
251 spin_lock_bh(&sp->lock);
252 /* We were not busy, so we are now... :-) */
253 netif_stop_queue(dev);
254 dev->stats.tx_bytes += skb->len;
255 sp_encaps(sp, skb->data, skb->len);
256 spin_unlock_bh(&sp->lock);
263 static int sp_open_dev(struct net_device *dev)
265 struct sixpack *sp = netdev_priv(dev);
272 /* Close the low-level part of the 6pack channel. */
273 static int sp_close(struct net_device *dev)
275 struct sixpack *sp = netdev_priv(dev);
277 spin_lock_bh(&sp->lock);
279 /* TTY discipline is running. */
280 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
282 netif_stop_queue(dev);
283 spin_unlock_bh(&sp->lock);
288 /* Return the frame type ID */
289 static int sp_header(struct sk_buff *skb, struct net_device *dev,
290 unsigned short type, const void *daddr,
291 const void *saddr, unsigned len)
294 if (type != ETH_P_AX25)
295 return ax25_hard_header(skb, dev, type, daddr, saddr, len);
300 static int sp_set_mac_address(struct net_device *dev, void *addr)
302 struct sockaddr_ax25 *sa = addr;
304 netif_tx_lock_bh(dev);
305 netif_addr_lock(dev);
306 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
307 netif_addr_unlock(dev);
308 netif_tx_unlock_bh(dev);
313 static int sp_rebuild_header(struct sk_buff *skb)
316 return ax25_rebuild_header(skb);
322 static const struct header_ops sp_header_ops = {
324 .rebuild = sp_rebuild_header,
327 static const struct net_device_ops sp_netdev_ops = {
328 .ndo_open = sp_open_dev,
329 .ndo_stop = sp_close,
330 .ndo_start_xmit = sp_xmit,
331 .ndo_set_mac_address = sp_set_mac_address,
334 static void sp_setup(struct net_device *dev)
336 /* Finish setting up the DEVICE info. */
337 dev->netdev_ops = &sp_netdev_ops;
338 dev->destructor = free_netdev;
340 dev->hard_header_len = AX25_MAX_HEADER_LEN;
341 dev->header_ops = &sp_header_ops;
343 dev->addr_len = AX25_ADDR_LEN;
344 dev->type = ARPHRD_AX25;
345 dev->tx_queue_len = 10;
347 /* Only activated in AX.25 mode */
348 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
349 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
354 /* Send one completely decapsulated IP datagram to the IP layer. */
357 * This is the routine that sends the received data to the kernel AX.25.
358 * 'cmd' is the KISS command. For AX.25 data, it is zero.
361 static void sp_bump(struct sixpack *sp, char cmd)
367 count = sp->rcount + 1;
369 sp->dev->stats.rx_bytes += count;
371 if ((skb = dev_alloc_skb(count)) == NULL)
374 ptr = skb_put(skb, count);
375 *ptr++ = cmd; /* KISS command */
377 memcpy(ptr, sp->cooked_buf + 1, count);
378 skb->protocol = ax25_type_trans(skb, sp->dev);
380 sp->dev->stats.rx_packets++;
385 sp->dev->stats.rx_dropped++;
389 /* ----------------------------------------------------------------------- */
392 * We have a potential race on dereferencing tty->disc_data, because the tty
393 * layer provides no locking at all - thus one cpu could be running
394 * sixpack_receive_buf while another calls sixpack_close, which zeroes
395 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
396 * best way to fix this is to use a rwlock in the tty struct, but for now we
397 * use a single global rwlock for all ttys in ppp line discipline.
399 static DEFINE_RWLOCK(disc_data_lock);
401 static struct sixpack *sp_get(struct tty_struct *tty)
405 read_lock(&disc_data_lock);
408 atomic_inc(&sp->refcnt);
409 read_unlock(&disc_data_lock);
414 static void sp_put(struct sixpack *sp)
416 if (atomic_dec_and_test(&sp->refcnt))
421 * Called by the TTY driver when there's room for more data. If we have
422 * more packets to send, we send them here.
424 static void sixpack_write_wakeup(struct tty_struct *tty)
426 struct sixpack *sp = sp_get(tty);
431 if (sp->xleft <= 0) {
432 /* Now serial buffer is almost free & we can start
433 * transmission of another packet */
434 sp->dev->stats.tx_packets++;
435 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
437 netif_wake_queue(sp->dev);
442 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
451 /* ----------------------------------------------------------------------- */
454 * Handle the 'receiver data ready' interrupt.
455 * This function is called by the 'tty_io' module in the kernel when
456 * a block of 6pack data has been received, which can now be decapsulated
457 * and sent on to some IP layer for further processing.
459 static unsigned int sixpack_receive_buf(struct tty_struct *tty,
460 const unsigned char *cp, char *fp, int count)
463 unsigned char buf[512];
473 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
475 /* Read the characters out of the buffer */
481 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
482 sp->dev->stats.rx_errors++;
486 sixpack_decode(sp, buf, count1);
495 * Try to resync the TNC. Called by the resync timer defined in
496 * decode_prio_command
499 #define TNC_UNINITIALIZED 0
500 #define TNC_UNSYNC_STARTUP 1
501 #define TNC_UNSYNCED 2
502 #define TNC_IN_SYNC 3
504 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
508 switch (new_tnc_state) {
509 default: /* gcc oh piece-o-crap ... */
510 case TNC_UNSYNC_STARTUP:
511 msg = "Synchronizing with TNC";
514 msg = "Lost synchronization with TNC\n";
521 sp->tnc_state = new_tnc_state;
522 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
525 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
527 int old_tnc_state = sp->tnc_state;
529 if (old_tnc_state != new_tnc_state)
530 __tnc_set_sync_state(sp, new_tnc_state);
533 static void resync_tnc(unsigned long channel)
535 struct sixpack *sp = (struct sixpack *) channel;
536 static char resync_cmd = 0xe8;
538 /* clear any data that might have been received */
541 sp->rx_count_cooked = 0;
543 /* reset state machine */
551 sp->led_state = 0x60;
552 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
553 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
556 /* Start resync timer again -- the TNC might be still absent */
558 del_timer(&sp->resync_t);
559 sp->resync_t.data = (unsigned long) sp;
560 sp->resync_t.function = resync_tnc;
561 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
562 add_timer(&sp->resync_t);
565 static inline int tnc_init(struct sixpack *sp)
567 unsigned char inbyte = 0xe8;
569 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
571 sp->tty->ops->write(sp->tty, &inbyte, 1);
573 del_timer(&sp->resync_t);
574 sp->resync_t.data = (unsigned long) sp;
575 sp->resync_t.function = resync_tnc;
576 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
577 add_timer(&sp->resync_t);
583 * Open the high-level part of the 6pack channel.
584 * This function is called by the TTY module when the
585 * 6pack line discipline is called for. Because we are
586 * sure the tty line exists, we only have to link it to
587 * a free 6pcack channel...
589 static int sixpack_open(struct tty_struct *tty)
591 char *rbuff = NULL, *xbuff = NULL;
592 struct net_device *dev;
597 if (!capable(CAP_NET_ADMIN))
599 if (tty->ops->write == NULL)
602 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
608 sp = netdev_priv(dev);
611 spin_lock_init(&sp->lock);
612 atomic_set(&sp->refcnt, 1);
613 sema_init(&sp->dead_sem, 0);
615 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
619 rbuff = kmalloc(len + 4, GFP_KERNEL);
620 xbuff = kmalloc(len + 4, GFP_KERNEL);
622 if (rbuff == NULL || xbuff == NULL) {
627 spin_lock_bh(&sp->lock);
634 sp->mtu = AX25_MTU + 73;
638 sp->rx_count_cooked = 0;
641 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
644 sp->tx_delay = SIXP_TXDELAY;
645 sp->persistence = SIXP_PERSIST;
646 sp->slottime = SIXP_SLOTTIME;
647 sp->led_state = 0x60;
653 netif_start_queue(dev);
655 init_timer(&sp->tx_t);
656 sp->tx_t.function = sp_xmit_on_air;
657 sp->tx_t.data = (unsigned long) sp;
659 init_timer(&sp->resync_t);
661 spin_unlock_bh(&sp->lock);
663 /* Done. We have linked the TTY line to a channel. */
665 tty->receive_room = 65536;
667 /* Now we're ready to register. */
668 if (register_netdev(dev))
688 * Close down a 6pack channel.
689 * This means flushing out any pending queues, and then restoring the
690 * TTY line discipline to what it was before it got hooked to 6pack
691 * (which usually is TTY again).
693 static void sixpack_close(struct tty_struct *tty)
697 write_lock(&disc_data_lock);
699 tty->disc_data = NULL;
700 write_unlock(&disc_data_lock);
705 * We have now ensured that nobody can start using ap from now on, but
706 * we have to wait for all existing users to finish.
708 if (!atomic_dec_and_test(&sp->refcnt))
711 unregister_netdev(sp->dev);
713 del_timer(&sp->tx_t);
714 del_timer(&sp->resync_t);
716 /* Free all 6pack frame buffers. */
721 /* Perform I/O control on an active 6pack channel. */
722 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
723 unsigned int cmd, unsigned long arg)
725 struct sixpack *sp = sp_get(tty);
726 struct net_device *dev;
727 unsigned int tmp, err;
735 err = copy_to_user((void __user *) arg, dev->name,
736 strlen(dev->name) + 1) ? -EFAULT : 0;
740 err = put_user(0, (int __user *) arg);
744 if (get_user(tmp, (int __user *) arg)) {
750 dev->addr_len = AX25_ADDR_LEN;
751 dev->hard_header_len = AX25_KISS_HEADER_LEN +
752 AX25_MAX_HEADER_LEN + 3;
753 dev->type = ARPHRD_AX25;
758 case SIOCSIFHWADDR: {
759 char addr[AX25_ADDR_LEN];
761 if (copy_from_user(&addr,
762 (void __user *) arg, AX25_ADDR_LEN)) {
767 netif_tx_lock_bh(dev);
768 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
769 netif_tx_unlock_bh(dev);
776 err = tty_mode_ioctl(tty, file, cmd, arg);
785 static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
786 unsigned int cmd, unsigned long arg)
793 return sixpack_ioctl(tty, file, cmd,
794 (unsigned long)compat_ptr(arg));
801 static struct tty_ldisc_ops sp_ldisc = {
802 .owner = THIS_MODULE,
803 .magic = TTY_LDISC_MAGIC,
805 .open = sixpack_open,
806 .close = sixpack_close,
807 .ioctl = sixpack_ioctl,
809 .compat_ioctl = sixpack_compat_ioctl,
811 .receive_buf = sixpack_receive_buf,
812 .write_wakeup = sixpack_write_wakeup,
815 /* Initialize 6pack control device -- register 6pack line discipline */
817 static const char msg_banner[] __initdata = KERN_INFO \
818 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
819 static const 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->ops->write(sp->tty, &sp->led_state, 1);
937 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
940 sp->led_state = 0x60;
946 /* needed to trigger the TNC watchdog */
947 sp->tty->ops->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->ops->write(sp->tty, &sp->led_state, 1);
980 sp->led_state = 0x60;
981 /* fill trailing bytes with zeroes */
982 sp->tty->ops->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);