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1/*
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.
5 *
6 * Authors: Andreas Könsgen <ajk@comnets.uni-bremen.de>
7 * Ralf Baechle DL5RB <ralf@linux-mips.org>
8 *
9 * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
10 *
11 * Laurence Culhane, <loz@holmes.demon.co.uk>
12 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
13 */
14
15#include <linux/module.h>
16#include <linux/uaccess.h>
17#include <linux/bitops.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/interrupt.h>
21#include <linux/in.h>
22#include <linux/tty.h>
23#include <linux/errno.h>
24#include <linux/netdevice.h>
25#include <linux/timer.h>
26#include <linux/slab.h>
27#include <net/ax25.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>
34#include <linux/ip.h>
35#include <linux/tcp.h>
36#include <linux/semaphore.h>
37#include <linux/compat.h>
38#include <linux/atomic.h>
39
40#define SIXPACK_VERSION "Revision: 0.3.0"
41
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 */
47
48#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
49
50/* masks to get certain bits out of the status bytes sent by the TNC */
51
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
62#define SIXP_CON 0x08
63#define SIXP_STA 0x10
64
65#define SIXP_FOUND_TNC 0xe9
66#define SIXP_CON_ON 0x68
67#define SIXP_DCD_MASK 0x08
68#define SIXP_DAMA_OFF 0
69
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 */
76
77/* 6pack configuration. */
78#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
79#define SIXP_MTU 256 /* Default MTU */
80
81enum sixpack_flags {
82 SIXPF_ERROR, /* Parity, etc. error */
83};
84
85struct sixpack {
86 /* Various fields. */
87 struct tty_struct *tty; /* ptr to TTY structure */
88 struct net_device *dev; /* easy for intr handling */
89
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 */
96
97 unsigned char raw_buf[4];
98 unsigned char cooked_buf[400];
99
100 unsigned int rx_count;
101 unsigned int rx_count_cooked;
102
103 int mtu; /* Our mtu (to spot changes!) */
104 int buffsize; /* Max buffers sizes */
105
106 unsigned long flags; /* Flag values/ mode etc */
107 unsigned char mode; /* 6pack mode */
108
109 /* 6pack stuff */
110 unsigned char tx_delay;
111 unsigned char persistence;
112 unsigned char slottime;
113 unsigned char duplex;
114 unsigned char led_state;
115 unsigned char status;
116 unsigned char status1;
117 unsigned char status2;
118 unsigned char tx_enable;
119 unsigned char tnc_state;
120
121 struct timer_list tx_t;
122 struct timer_list resync_t;
123 atomic_t refcnt;
124 struct semaphore dead_sem;
125 spinlock_t lock;
126};
127
128#define AX25_6PACK_HEADER_LEN 0
129
130static void sixpack_decode(struct sixpack *, const unsigned char[], int);
131static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
132
133/*
134 * Perform the persistence/slottime algorithm for CSMA access. If the
135 * persistence check was successful, write the data to the serial driver.
136 * Note that in case of DAMA operation, the data is not sent here.
137 */
138
139static void sp_xmit_on_air(unsigned long channel)
140{
141 struct sixpack *sp = (struct sixpack *) channel;
142 int actual, when = sp->slottime;
143 static unsigned char random;
144
145 random = random * 17 + 41;
146
147 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
148 sp->led_state = 0x70;
149 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
150 sp->tx_enable = 1;
151 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
152 sp->xleft -= actual;
153 sp->xhead += actual;
154 sp->led_state = 0x60;
155 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
156 sp->status2 = 0;
157 } else
158 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
159}
160
161/* ----> 6pack timer interrupt handler and friends. <---- */
162
163/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
164static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
165{
166 unsigned char *msg, *p = icp;
167 int actual, count;
168
169 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
170 msg = "oversized transmit packet!";
171 goto out_drop;
172 }
173
174 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
175 msg = "oversized transmit packet!";
176 goto out_drop;
177 }
178
179 if (p[0] > 5) {
180 msg = "invalid KISS command";
181 goto out_drop;
182 }
183
184 if ((p[0] != 0) && (len > 2)) {
185 msg = "KISS control packet too long";
186 goto out_drop;
187 }
188
189 if ((p[0] == 0) && (len < 15)) {
190 msg = "bad AX.25 packet to transmit";
191 goto out_drop;
192 }
193
194 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
195 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
196
197 switch (p[0]) {
198 case 1: sp->tx_delay = p[1];
199 return;
200 case 2: sp->persistence = p[1];
201 return;
202 case 3: sp->slottime = p[1];
203 return;
204 case 4: /* ignored */
205 return;
206 case 5: sp->duplex = p[1];
207 return;
208 }
209
210 if (p[0] != 0)
211 return;
212
213 /*
214 * In case of fullduplex or DAMA operation, we don't take care about the
215 * state of the DCD or of any timers, as the determination of the
216 * correct time to send is the job of the AX.25 layer. We send
217 * immediately after data has arrived.
218 */
219 if (sp->duplex == 1) {
220 sp->led_state = 0x70;
221 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
222 sp->tx_enable = 1;
223 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
224 sp->xleft = count - actual;
225 sp->xhead = sp->xbuff + actual;
226 sp->led_state = 0x60;
227 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
228 } else {
229 sp->xleft = count;
230 sp->xhead = sp->xbuff;
231 sp->status2 = count;
232 sp_xmit_on_air((unsigned long)sp);
233 }
234
235 return;
236
237out_drop:
238 sp->dev->stats.tx_dropped++;
239 netif_start_queue(sp->dev);
240 if (net_ratelimit())
241 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
242}
243
244/* Encapsulate an IP datagram and kick it into a TTY queue. */
245
246static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
247{
248 struct sixpack *sp = netdev_priv(dev);
249
250 if (skb->protocol == htons(ETH_P_IP))
251 return ax25_ip_xmit(skb);
252
253 spin_lock_bh(&sp->lock);
254 /* We were not busy, so we are now... :-) */
255 netif_stop_queue(dev);
256 dev->stats.tx_bytes += skb->len;
257 sp_encaps(sp, skb->data, skb->len);
258 spin_unlock_bh(&sp->lock);
259
260 dev_kfree_skb(skb);
261
262 return NETDEV_TX_OK;
263}
264
265static int sp_open_dev(struct net_device *dev)
266{
267 struct sixpack *sp = netdev_priv(dev);
268
269 if (sp->tty == NULL)
270 return -ENODEV;
271 return 0;
272}
273
274/* Close the low-level part of the 6pack channel. */
275static int sp_close(struct net_device *dev)
276{
277 struct sixpack *sp = netdev_priv(dev);
278
279 spin_lock_bh(&sp->lock);
280 if (sp->tty) {
281 /* TTY discipline is running. */
282 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
283 }
284 netif_stop_queue(dev);
285 spin_unlock_bh(&sp->lock);
286
287 return 0;
288}
289
290static int sp_set_mac_address(struct net_device *dev, void *addr)
291{
292 struct sockaddr_ax25 *sa = addr;
293
294 netif_tx_lock_bh(dev);
295 netif_addr_lock(dev);
296 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
297 netif_addr_unlock(dev);
298 netif_tx_unlock_bh(dev);
299
300 return 0;
301}
302
303static const struct net_device_ops sp_netdev_ops = {
304 .ndo_open = sp_open_dev,
305 .ndo_stop = sp_close,
306 .ndo_start_xmit = sp_xmit,
307 .ndo_set_mac_address = sp_set_mac_address,
308};
309
310static void sp_setup(struct net_device *dev)
311{
312 /* Finish setting up the DEVICE info. */
313 dev->netdev_ops = &sp_netdev_ops;
314 dev->destructor = free_netdev;
315 dev->mtu = SIXP_MTU;
316 dev->hard_header_len = AX25_MAX_HEADER_LEN;
317 dev->header_ops = &ax25_header_ops;
318
319 dev->addr_len = AX25_ADDR_LEN;
320 dev->type = ARPHRD_AX25;
321 dev->tx_queue_len = 10;
322
323 /* Only activated in AX.25 mode */
324 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
325 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
326
327 dev->flags = 0;
328}
329
330/* Send one completely decapsulated IP datagram to the IP layer. */
331
332/*
333 * This is the routine that sends the received data to the kernel AX.25.
334 * 'cmd' is the KISS command. For AX.25 data, it is zero.
335 */
336
337static void sp_bump(struct sixpack *sp, char cmd)
338{
339 struct sk_buff *skb;
340 int count;
341 unsigned char *ptr;
342
343 count = sp->rcount + 1;
344
345 sp->dev->stats.rx_bytes += count;
346
347 if ((skb = dev_alloc_skb(count)) == NULL)
348 goto out_mem;
349
350 ptr = skb_put(skb, count);
351 *ptr++ = cmd; /* KISS command */
352
353 memcpy(ptr, sp->cooked_buf + 1, count);
354 skb->protocol = ax25_type_trans(skb, sp->dev);
355 netif_rx(skb);
356 sp->dev->stats.rx_packets++;
357
358 return;
359
360out_mem:
361 sp->dev->stats.rx_dropped++;
362}
363
364
365/* ----------------------------------------------------------------------- */
366
367/*
368 * We have a potential race on dereferencing tty->disc_data, because the tty
369 * layer provides no locking at all - thus one cpu could be running
370 * sixpack_receive_buf while another calls sixpack_close, which zeroes
371 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
372 * best way to fix this is to use a rwlock in the tty struct, but for now we
373 * use a single global rwlock for all ttys in ppp line discipline.
374 */
375static DEFINE_RWLOCK(disc_data_lock);
376
377static struct sixpack *sp_get(struct tty_struct *tty)
378{
379 struct sixpack *sp;
380
381 read_lock(&disc_data_lock);
382 sp = tty->disc_data;
383 if (sp)
384 atomic_inc(&sp->refcnt);
385 read_unlock(&disc_data_lock);
386
387 return sp;
388}
389
390static void sp_put(struct sixpack *sp)
391{
392 if (atomic_dec_and_test(&sp->refcnt))
393 up(&sp->dead_sem);
394}
395
396/*
397 * Called by the TTY driver when there's room for more data. If we have
398 * more packets to send, we send them here.
399 */
400static void sixpack_write_wakeup(struct tty_struct *tty)
401{
402 struct sixpack *sp = sp_get(tty);
403 int actual;
404
405 if (!sp)
406 return;
407 if (sp->xleft <= 0) {
408 /* Now serial buffer is almost free & we can start
409 * transmission of another packet */
410 sp->dev->stats.tx_packets++;
411 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
412 sp->tx_enable = 0;
413 netif_wake_queue(sp->dev);
414 goto out;
415 }
416
417 if (sp->tx_enable) {
418 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
419 sp->xleft -= actual;
420 sp->xhead += actual;
421 }
422
423out:
424 sp_put(sp);
425}
426
427/* ----------------------------------------------------------------------- */
428
429/*
430 * Handle the 'receiver data ready' interrupt.
431 * This function is called by the tty module in the kernel when
432 * a block of 6pack data has been received, which can now be decapsulated
433 * and sent on to some IP layer for further processing.
434 */
435static void sixpack_receive_buf(struct tty_struct *tty,
436 const unsigned char *cp, char *fp, int count)
437{
438 struct sixpack *sp;
439 int count1;
440
441 if (!count)
442 return;
443
444 sp = sp_get(tty);
445 if (!sp)
446 return;
447
448 /* Read the characters out of the buffer */
449 count1 = count;
450 while (count) {
451 count--;
452 if (fp && *fp++) {
453 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
454 sp->dev->stats.rx_errors++;
455 continue;
456 }
457 }
458 sixpack_decode(sp, cp, count1);
459
460 sp_put(sp);
461 tty_unthrottle(tty);
462}
463
464/*
465 * Try to resync the TNC. Called by the resync timer defined in
466 * decode_prio_command
467 */
468
469#define TNC_UNINITIALIZED 0
470#define TNC_UNSYNC_STARTUP 1
471#define TNC_UNSYNCED 2
472#define TNC_IN_SYNC 3
473
474static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
475{
476 char *msg;
477
478 switch (new_tnc_state) {
479 default: /* gcc oh piece-o-crap ... */
480 case TNC_UNSYNC_STARTUP:
481 msg = "Synchronizing with TNC";
482 break;
483 case TNC_UNSYNCED:
484 msg = "Lost synchronization with TNC\n";
485 break;
486 case TNC_IN_SYNC:
487 msg = "Found TNC";
488 break;
489 }
490
491 sp->tnc_state = new_tnc_state;
492 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
493}
494
495static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
496{
497 int old_tnc_state = sp->tnc_state;
498
499 if (old_tnc_state != new_tnc_state)
500 __tnc_set_sync_state(sp, new_tnc_state);
501}
502
503static void resync_tnc(unsigned long channel)
504{
505 struct sixpack *sp = (struct sixpack *) channel;
506 static char resync_cmd = 0xe8;
507
508 /* clear any data that might have been received */
509
510 sp->rx_count = 0;
511 sp->rx_count_cooked = 0;
512
513 /* reset state machine */
514
515 sp->status = 1;
516 sp->status1 = 1;
517 sp->status2 = 0;
518
519 /* resync the TNC */
520
521 sp->led_state = 0x60;
522 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
523 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
524
525
526 /* Start resync timer again -- the TNC might be still absent */
527
528 del_timer(&sp->resync_t);
529 sp->resync_t.data = (unsigned long) sp;
530 sp->resync_t.function = resync_tnc;
531 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
532 add_timer(&sp->resync_t);
533}
534
535static inline int tnc_init(struct sixpack *sp)
536{
537 unsigned char inbyte = 0xe8;
538
539 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
540
541 sp->tty->ops->write(sp->tty, &inbyte, 1);
542
543 del_timer(&sp->resync_t);
544 sp->resync_t.data = (unsigned long) sp;
545 sp->resync_t.function = resync_tnc;
546 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
547 add_timer(&sp->resync_t);
548
549 return 0;
550}
551
552/*
553 * Open the high-level part of the 6pack channel.
554 * This function is called by the TTY module when the
555 * 6pack line discipline is called for. Because we are
556 * sure the tty line exists, we only have to link it to
557 * a free 6pcack channel...
558 */
559static int sixpack_open(struct tty_struct *tty)
560{
561 char *rbuff = NULL, *xbuff = NULL;
562 struct net_device *dev;
563 struct sixpack *sp;
564 unsigned long len;
565 int err = 0;
566
567 if (!capable(CAP_NET_ADMIN))
568 return -EPERM;
569 if (tty->ops->write == NULL)
570 return -EOPNOTSUPP;
571
572 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
573 sp_setup);
574 if (!dev) {
575 err = -ENOMEM;
576 goto out;
577 }
578
579 sp = netdev_priv(dev);
580 sp->dev = dev;
581
582 spin_lock_init(&sp->lock);
583 atomic_set(&sp->refcnt, 1);
584 sema_init(&sp->dead_sem, 0);
585
586 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
587
588 len = dev->mtu * 2;
589
590 rbuff = kmalloc(len + 4, GFP_KERNEL);
591 xbuff = kmalloc(len + 4, GFP_KERNEL);
592
593 if (rbuff == NULL || xbuff == NULL) {
594 err = -ENOBUFS;
595 goto out_free;
596 }
597
598 spin_lock_bh(&sp->lock);
599
600 sp->tty = tty;
601
602 sp->rbuff = rbuff;
603 sp->xbuff = xbuff;
604
605 sp->mtu = AX25_MTU + 73;
606 sp->buffsize = len;
607 sp->rcount = 0;
608 sp->rx_count = 0;
609 sp->rx_count_cooked = 0;
610 sp->xleft = 0;
611
612 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
613
614 sp->duplex = 0;
615 sp->tx_delay = SIXP_TXDELAY;
616 sp->persistence = SIXP_PERSIST;
617 sp->slottime = SIXP_SLOTTIME;
618 sp->led_state = 0x60;
619 sp->status = 1;
620 sp->status1 = 1;
621 sp->status2 = 0;
622 sp->tx_enable = 0;
623
624 netif_start_queue(dev);
625
626 init_timer(&sp->tx_t);
627 sp->tx_t.function = sp_xmit_on_air;
628 sp->tx_t.data = (unsigned long) sp;
629
630 init_timer(&sp->resync_t);
631
632 spin_unlock_bh(&sp->lock);
633
634 /* Done. We have linked the TTY line to a channel. */
635 tty->disc_data = sp;
636 tty->receive_room = 65536;
637
638 /* Now we're ready to register. */
639 err = register_netdev(dev);
640 if (err)
641 goto out_free;
642
643 tnc_init(sp);
644
645 return 0;
646
647out_free:
648 kfree(xbuff);
649 kfree(rbuff);
650
651 free_netdev(dev);
652
653out:
654 return err;
655}
656
657
658/*
659 * Close down a 6pack channel.
660 * This means flushing out any pending queues, and then restoring the
661 * TTY line discipline to what it was before it got hooked to 6pack
662 * (which usually is TTY again).
663 */
664static void sixpack_close(struct tty_struct *tty)
665{
666 struct sixpack *sp;
667
668 write_lock_bh(&disc_data_lock);
669 sp = tty->disc_data;
670 tty->disc_data = NULL;
671 write_unlock_bh(&disc_data_lock);
672 if (!sp)
673 return;
674
675 /*
676 * We have now ensured that nobody can start using ap from now on, but
677 * we have to wait for all existing users to finish.
678 */
679 if (!atomic_dec_and_test(&sp->refcnt))
680 down(&sp->dead_sem);
681
682 /* We must stop the queue to avoid potentially scribbling
683 * on the free buffers. The sp->dead_sem is not sufficient
684 * to protect us from sp->xbuff access.
685 */
686 netif_stop_queue(sp->dev);
687
688 del_timer_sync(&sp->tx_t);
689 del_timer_sync(&sp->resync_t);
690
691 /* Free all 6pack frame buffers. */
692 kfree(sp->rbuff);
693 kfree(sp->xbuff);
694
695 unregister_netdev(sp->dev);
696}
697
698/* Perform I/O control on an active 6pack channel. */
699static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
700 unsigned int cmd, unsigned long arg)
701{
702 struct sixpack *sp = sp_get(tty);
703 struct net_device *dev;
704 unsigned int tmp, err;
705
706 if (!sp)
707 return -ENXIO;
708 dev = sp->dev;
709
710 switch(cmd) {
711 case SIOCGIFNAME:
712 err = copy_to_user((void __user *) arg, dev->name,
713 strlen(dev->name) + 1) ? -EFAULT : 0;
714 break;
715
716 case SIOCGIFENCAP:
717 err = put_user(0, (int __user *) arg);
718 break;
719
720 case SIOCSIFENCAP:
721 if (get_user(tmp, (int __user *) arg)) {
722 err = -EFAULT;
723 break;
724 }
725
726 sp->mode = tmp;
727 dev->addr_len = AX25_ADDR_LEN;
728 dev->hard_header_len = AX25_KISS_HEADER_LEN +
729 AX25_MAX_HEADER_LEN + 3;
730 dev->type = ARPHRD_AX25;
731
732 err = 0;
733 break;
734
735 case SIOCSIFHWADDR: {
736 char addr[AX25_ADDR_LEN];
737
738 if (copy_from_user(&addr,
739 (void __user *) arg, AX25_ADDR_LEN)) {
740 err = -EFAULT;
741 break;
742 }
743
744 netif_tx_lock_bh(dev);
745 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
746 netif_tx_unlock_bh(dev);
747
748 err = 0;
749 break;
750 }
751
752 default:
753 err = tty_mode_ioctl(tty, file, cmd, arg);
754 }
755
756 sp_put(sp);
757
758 return err;
759}
760
761#ifdef CONFIG_COMPAT
762static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
763 unsigned int cmd, unsigned long arg)
764{
765 switch (cmd) {
766 case SIOCGIFNAME:
767 case SIOCGIFENCAP:
768 case SIOCSIFENCAP:
769 case SIOCSIFHWADDR:
770 return sixpack_ioctl(tty, file, cmd,
771 (unsigned long)compat_ptr(arg));
772 }
773
774 return -ENOIOCTLCMD;
775}
776#endif
777
778static struct tty_ldisc_ops sp_ldisc = {
779 .owner = THIS_MODULE,
780 .magic = TTY_LDISC_MAGIC,
781 .name = "6pack",
782 .open = sixpack_open,
783 .close = sixpack_close,
784 .ioctl = sixpack_ioctl,
785#ifdef CONFIG_COMPAT
786 .compat_ioctl = sixpack_compat_ioctl,
787#endif
788 .receive_buf = sixpack_receive_buf,
789 .write_wakeup = sixpack_write_wakeup,
790};
791
792/* Initialize 6pack control device -- register 6pack line discipline */
793
794static const char msg_banner[] __initconst = KERN_INFO \
795 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
796static const char msg_regfail[] __initconst = KERN_ERR \
797 "6pack: can't register line discipline (err = %d)\n";
798
799static int __init sixpack_init_driver(void)
800{
801 int status;
802
803 printk(msg_banner);
804
805 /* Register the provided line protocol discipline */
806 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
807 printk(msg_regfail, status);
808
809 return status;
810}
811
812static const char msg_unregfail[] = KERN_ERR \
813 "6pack: can't unregister line discipline (err = %d)\n";
814
815static void __exit sixpack_exit_driver(void)
816{
817 int ret;
818
819 if ((ret = tty_unregister_ldisc(N_6PACK)))
820 printk(msg_unregfail, ret);
821}
822
823/* encode an AX.25 packet into 6pack */
824
825static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
826 int length, unsigned char tx_delay)
827{
828 int count = 0;
829 unsigned char checksum = 0, buf[400];
830 int raw_count = 0;
831
832 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
833 tx_buf_raw[raw_count++] = SIXP_SEOF;
834
835 buf[0] = tx_delay;
836 for (count = 1; count < length; count++)
837 buf[count] = tx_buf[count];
838
839 for (count = 0; count < length; count++)
840 checksum += buf[count];
841 buf[length] = (unsigned char) 0xff - checksum;
842
843 for (count = 0; count <= length; count++) {
844 if ((count % 3) == 0) {
845 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
846 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
847 } else if ((count % 3) == 1) {
848 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
849 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
850 } else {
851 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
852 tx_buf_raw[raw_count++] = (buf[count] >> 2);
853 }
854 }
855 if ((length % 3) != 2)
856 raw_count++;
857 tx_buf_raw[raw_count++] = SIXP_SEOF;
858 return raw_count;
859}
860
861/* decode 4 sixpack-encoded bytes into 3 data bytes */
862
863static void decode_data(struct sixpack *sp, unsigned char inbyte)
864{
865 unsigned char *buf;
866
867 if (sp->rx_count != 3) {
868 sp->raw_buf[sp->rx_count++] = inbyte;
869
870 return;
871 }
872
873 buf = sp->raw_buf;
874 sp->cooked_buf[sp->rx_count_cooked++] =
875 buf[0] | ((buf[1] << 2) & 0xc0);
876 sp->cooked_buf[sp->rx_count_cooked++] =
877 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
878 sp->cooked_buf[sp->rx_count_cooked++] =
879 (buf[2] & 0x03) | (inbyte << 2);
880 sp->rx_count = 0;
881}
882
883/* identify and execute a 6pack priority command byte */
884
885static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
886{
887 unsigned char channel;
888 int actual;
889
890 channel = cmd & SIXP_CHN_MASK;
891 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
892
893 /* RX and DCD flags can only be set in the same prio command,
894 if the DCD flag has been set without the RX flag in the previous
895 prio command. If DCD has not been set before, something in the
896 transmission has gone wrong. In this case, RX and DCD are
897 cleared in order to prevent the decode_data routine from
898 reading further data that might be corrupt. */
899
900 if (((sp->status & SIXP_DCD_MASK) == 0) &&
901 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
902 if (sp->status != 1)
903 printk(KERN_DEBUG "6pack: protocol violation\n");
904 else
905 sp->status = 0;
906 cmd &= ~SIXP_RX_DCD_MASK;
907 }
908 sp->status = cmd & SIXP_PRIO_DATA_MASK;
909 } else { /* output watchdog char if idle */
910 if ((sp->status2 != 0) && (sp->duplex == 1)) {
911 sp->led_state = 0x70;
912 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
913 sp->tx_enable = 1;
914 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
915 sp->xleft -= actual;
916 sp->xhead += actual;
917 sp->led_state = 0x60;
918 sp->status2 = 0;
919
920 }
921 }
922
923 /* needed to trigger the TNC watchdog */
924 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
925
926 /* if the state byte has been received, the TNC is present,
927 so the resync timer can be reset. */
928
929 if (sp->tnc_state == TNC_IN_SYNC) {
930 del_timer(&sp->resync_t);
931 sp->resync_t.data = (unsigned long) sp;
932 sp->resync_t.function = resync_tnc;
933 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
934 add_timer(&sp->resync_t);
935 }
936
937 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
938}
939
940/* identify and execute a standard 6pack command byte */
941
942static void decode_std_command(struct sixpack *sp, unsigned char cmd)
943{
944 unsigned char checksum = 0, rest = 0, channel;
945 short i;
946
947 channel = cmd & SIXP_CHN_MASK;
948 switch (cmd & SIXP_CMD_MASK) { /* normal command */
949 case SIXP_SEOF:
950 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
951 if ((sp->status & SIXP_RX_DCD_MASK) ==
952 SIXP_RX_DCD_MASK) {
953 sp->led_state = 0x68;
954 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
955 }
956 } else {
957 sp->led_state = 0x60;
958 /* fill trailing bytes with zeroes */
959 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
960 rest = sp->rx_count;
961 if (rest != 0)
962 for (i = rest; i <= 3; i++)
963 decode_data(sp, 0);
964 if (rest == 2)
965 sp->rx_count_cooked -= 2;
966 else if (rest == 3)
967 sp->rx_count_cooked -= 1;
968 for (i = 0; i < sp->rx_count_cooked; i++)
969 checksum += sp->cooked_buf[i];
970 if (checksum != SIXP_CHKSUM) {
971 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
972 } else {
973 sp->rcount = sp->rx_count_cooked-2;
974 sp_bump(sp, 0);
975 }
976 sp->rx_count_cooked = 0;
977 }
978 break;
979 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
980 break;
981 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
982 break;
983 case SIXP_RX_BUF_OVL:
984 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
985 }
986}
987
988/* decode a 6pack packet */
989
990static void
991sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
992{
993 unsigned char inbyte;
994 int count1;
995
996 for (count1 = 0; count1 < count; count1++) {
997 inbyte = pre_rbuff[count1];
998 if (inbyte == SIXP_FOUND_TNC) {
999 tnc_set_sync_state(sp, TNC_IN_SYNC);
1000 del_timer(&sp->resync_t);
1001 }
1002 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1003 decode_prio_command(sp, inbyte);
1004 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1005 decode_std_command(sp, inbyte);
1006 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1007 decode_data(sp, inbyte);
1008 }
1009}
1010
1011MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1012MODULE_DESCRIPTION("6pack driver for AX.25");
1013MODULE_LICENSE("GPL");
1014MODULE_ALIAS_LDISC(N_6PACK);
1015
1016module_init(sixpack_init_driver);
1017module_exit(sixpack_exit_driver);
1/*
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.
5 *
6 * Authors: Andreas Könsgen <ajk@comnets.uni-bremen.de>
7 * Ralf Baechle DL5RB <ralf@linux-mips.org>
8 *
9 * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
10 *
11 * Laurence Culhane, <loz@holmes.demon.co.uk>
12 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
13 */
14
15#include <linux/module.h>
16#include <asm/uaccess.h>
17#include <linux/bitops.h>
18#include <linux/string.h>
19#include <linux/mm.h>
20#include <linux/interrupt.h>
21#include <linux/in.h>
22#include <linux/tty.h>
23#include <linux/errno.h>
24#include <linux/netdevice.h>
25#include <linux/timer.h>
26#include <linux/slab.h>
27#include <net/ax25.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>
34#include <linux/ip.h>
35#include <linux/tcp.h>
36#include <linux/semaphore.h>
37#include <linux/compat.h>
38#include <linux/atomic.h>
39
40#define SIXPACK_VERSION "Revision: 0.3.0"
41
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 */
47
48#define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
49
50/* masks to get certain bits out of the status bytes sent by the TNC */
51
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
62#define SIXP_CON 0x08
63#define SIXP_STA 0x10
64
65#define SIXP_FOUND_TNC 0xe9
66#define SIXP_CON_ON 0x68
67#define SIXP_DCD_MASK 0x08
68#define SIXP_DAMA_OFF 0
69
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 */
76
77/* 6pack configuration. */
78#define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
79#define SIXP_MTU 256 /* Default MTU */
80
81enum sixpack_flags {
82 SIXPF_ERROR, /* Parity, etc. error */
83};
84
85struct sixpack {
86 /* Various fields. */
87 struct tty_struct *tty; /* ptr to TTY structure */
88 struct net_device *dev; /* easy for intr handling */
89
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 */
96
97 unsigned char raw_buf[4];
98 unsigned char cooked_buf[400];
99
100 unsigned int rx_count;
101 unsigned int rx_count_cooked;
102
103 int mtu; /* Our mtu (to spot changes!) */
104 int buffsize; /* Max buffers sizes */
105
106 unsigned long flags; /* Flag values/ mode etc */
107 unsigned char mode; /* 6pack mode */
108
109 /* 6pack stuff */
110 unsigned char tx_delay;
111 unsigned char persistence;
112 unsigned char slottime;
113 unsigned char duplex;
114 unsigned char led_state;
115 unsigned char status;
116 unsigned char status1;
117 unsigned char status2;
118 unsigned char tx_enable;
119 unsigned char tnc_state;
120
121 struct timer_list tx_t;
122 struct timer_list resync_t;
123 atomic_t refcnt;
124 struct semaphore dead_sem;
125 spinlock_t lock;
126};
127
128#define AX25_6PACK_HEADER_LEN 0
129
130static void sixpack_decode(struct sixpack *, unsigned char[], int);
131static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
132
133/*
134 * Perform the persistence/slottime algorithm for CSMA access. If the
135 * persistence check was successful, write the data to the serial driver.
136 * Note that in case of DAMA operation, the data is not sent here.
137 */
138
139static void sp_xmit_on_air(unsigned long channel)
140{
141 struct sixpack *sp = (struct sixpack *) channel;
142 int actual, when = sp->slottime;
143 static unsigned char random;
144
145 random = random * 17 + 41;
146
147 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
148 sp->led_state = 0x70;
149 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
150 sp->tx_enable = 1;
151 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
152 sp->xleft -= actual;
153 sp->xhead += actual;
154 sp->led_state = 0x60;
155 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
156 sp->status2 = 0;
157 } else
158 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
159}
160
161/* ----> 6pack timer interrupt handler and friends. <---- */
162
163/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
164static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
165{
166 unsigned char *msg, *p = icp;
167 int actual, count;
168
169 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
170 msg = "oversized transmit packet!";
171 goto out_drop;
172 }
173
174 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
175 msg = "oversized transmit packet!";
176 goto out_drop;
177 }
178
179 if (p[0] > 5) {
180 msg = "invalid KISS command";
181 goto out_drop;
182 }
183
184 if ((p[0] != 0) && (len > 2)) {
185 msg = "KISS control packet too long";
186 goto out_drop;
187 }
188
189 if ((p[0] == 0) && (len < 15)) {
190 msg = "bad AX.25 packet to transmit";
191 goto out_drop;
192 }
193
194 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
195 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
196
197 switch (p[0]) {
198 case 1: sp->tx_delay = p[1];
199 return;
200 case 2: sp->persistence = p[1];
201 return;
202 case 3: sp->slottime = p[1];
203 return;
204 case 4: /* ignored */
205 return;
206 case 5: sp->duplex = p[1];
207 return;
208 }
209
210 if (p[0] != 0)
211 return;
212
213 /*
214 * In case of fullduplex or DAMA operation, we don't take care about the
215 * state of the DCD or of any timers, as the determination of the
216 * correct time to send is the job of the AX.25 layer. We send
217 * immediately after data has arrived.
218 */
219 if (sp->duplex == 1) {
220 sp->led_state = 0x70;
221 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
222 sp->tx_enable = 1;
223 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
224 sp->xleft = count - actual;
225 sp->xhead = sp->xbuff + actual;
226 sp->led_state = 0x60;
227 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
228 } else {
229 sp->xleft = count;
230 sp->xhead = sp->xbuff;
231 sp->status2 = count;
232 sp_xmit_on_air((unsigned long)sp);
233 }
234
235 return;
236
237out_drop:
238 sp->dev->stats.tx_dropped++;
239 netif_start_queue(sp->dev);
240 if (net_ratelimit())
241 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
242}
243
244/* Encapsulate an IP datagram and kick it into a TTY queue. */
245
246static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
247{
248 struct sixpack *sp = netdev_priv(dev);
249
250 if (skb->protocol == htons(ETH_P_IP))
251 return ax25_ip_xmit(skb);
252
253 spin_lock_bh(&sp->lock);
254 /* We were not busy, so we are now... :-) */
255 netif_stop_queue(dev);
256 dev->stats.tx_bytes += skb->len;
257 sp_encaps(sp, skb->data, skb->len);
258 spin_unlock_bh(&sp->lock);
259
260 dev_kfree_skb(skb);
261
262 return NETDEV_TX_OK;
263}
264
265static int sp_open_dev(struct net_device *dev)
266{
267 struct sixpack *sp = netdev_priv(dev);
268
269 if (sp->tty == NULL)
270 return -ENODEV;
271 return 0;
272}
273
274/* Close the low-level part of the 6pack channel. */
275static int sp_close(struct net_device *dev)
276{
277 struct sixpack *sp = netdev_priv(dev);
278
279 spin_lock_bh(&sp->lock);
280 if (sp->tty) {
281 /* TTY discipline is running. */
282 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
283 }
284 netif_stop_queue(dev);
285 spin_unlock_bh(&sp->lock);
286
287 return 0;
288}
289
290static int sp_set_mac_address(struct net_device *dev, void *addr)
291{
292 struct sockaddr_ax25 *sa = addr;
293
294 netif_tx_lock_bh(dev);
295 netif_addr_lock(dev);
296 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
297 netif_addr_unlock(dev);
298 netif_tx_unlock_bh(dev);
299
300 return 0;
301}
302
303static const struct net_device_ops sp_netdev_ops = {
304 .ndo_open = sp_open_dev,
305 .ndo_stop = sp_close,
306 .ndo_start_xmit = sp_xmit,
307 .ndo_set_mac_address = sp_set_mac_address,
308};
309
310static void sp_setup(struct net_device *dev)
311{
312 /* Finish setting up the DEVICE info. */
313 dev->netdev_ops = &sp_netdev_ops;
314 dev->destructor = free_netdev;
315 dev->mtu = SIXP_MTU;
316 dev->hard_header_len = AX25_MAX_HEADER_LEN;
317 dev->header_ops = &ax25_header_ops;
318
319 dev->addr_len = AX25_ADDR_LEN;
320 dev->type = ARPHRD_AX25;
321 dev->tx_queue_len = 10;
322
323 /* Only activated in AX.25 mode */
324 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
325 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
326
327 dev->flags = 0;
328}
329
330/* Send one completely decapsulated IP datagram to the IP layer. */
331
332/*
333 * This is the routine that sends the received data to the kernel AX.25.
334 * 'cmd' is the KISS command. For AX.25 data, it is zero.
335 */
336
337static void sp_bump(struct sixpack *sp, char cmd)
338{
339 struct sk_buff *skb;
340 int count;
341 unsigned char *ptr;
342
343 count = sp->rcount + 1;
344
345 sp->dev->stats.rx_bytes += count;
346
347 if ((skb = dev_alloc_skb(count)) == NULL)
348 goto out_mem;
349
350 ptr = skb_put(skb, count);
351 *ptr++ = cmd; /* KISS command */
352
353 memcpy(ptr, sp->cooked_buf + 1, count);
354 skb->protocol = ax25_type_trans(skb, sp->dev);
355 netif_rx(skb);
356 sp->dev->stats.rx_packets++;
357
358 return;
359
360out_mem:
361 sp->dev->stats.rx_dropped++;
362}
363
364
365/* ----------------------------------------------------------------------- */
366
367/*
368 * We have a potential race on dereferencing tty->disc_data, because the tty
369 * layer provides no locking at all - thus one cpu could be running
370 * sixpack_receive_buf while another calls sixpack_close, which zeroes
371 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
372 * best way to fix this is to use a rwlock in the tty struct, but for now we
373 * use a single global rwlock for all ttys in ppp line discipline.
374 */
375static DEFINE_RWLOCK(disc_data_lock);
376
377static struct sixpack *sp_get(struct tty_struct *tty)
378{
379 struct sixpack *sp;
380
381 read_lock(&disc_data_lock);
382 sp = tty->disc_data;
383 if (sp)
384 atomic_inc(&sp->refcnt);
385 read_unlock(&disc_data_lock);
386
387 return sp;
388}
389
390static void sp_put(struct sixpack *sp)
391{
392 if (atomic_dec_and_test(&sp->refcnt))
393 up(&sp->dead_sem);
394}
395
396/*
397 * Called by the TTY driver when there's room for more data. If we have
398 * more packets to send, we send them here.
399 */
400static void sixpack_write_wakeup(struct tty_struct *tty)
401{
402 struct sixpack *sp = sp_get(tty);
403 int actual;
404
405 if (!sp)
406 return;
407 if (sp->xleft <= 0) {
408 /* Now serial buffer is almost free & we can start
409 * transmission of another packet */
410 sp->dev->stats.tx_packets++;
411 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
412 sp->tx_enable = 0;
413 netif_wake_queue(sp->dev);
414 goto out;
415 }
416
417 if (sp->tx_enable) {
418 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
419 sp->xleft -= actual;
420 sp->xhead += actual;
421 }
422
423out:
424 sp_put(sp);
425}
426
427/* ----------------------------------------------------------------------- */
428
429/*
430 * Handle the 'receiver data ready' interrupt.
431 * This function is called by the 'tty_io' module in the kernel when
432 * a block of 6pack data has been received, which can now be decapsulated
433 * and sent on to some IP layer for further processing.
434 */
435static void sixpack_receive_buf(struct tty_struct *tty,
436 const unsigned char *cp, char *fp, int count)
437{
438 struct sixpack *sp;
439 unsigned char buf[512];
440 int count1;
441
442 if (!count)
443 return;
444
445 sp = sp_get(tty);
446 if (!sp)
447 return;
448
449 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
450
451 /* Read the characters out of the buffer */
452
453 count1 = count;
454 while (count) {
455 count--;
456 if (fp && *fp++) {
457 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
458 sp->dev->stats.rx_errors++;
459 continue;
460 }
461 }
462 sixpack_decode(sp, buf, count1);
463
464 sp_put(sp);
465 tty_unthrottle(tty);
466}
467
468/*
469 * Try to resync the TNC. Called by the resync timer defined in
470 * decode_prio_command
471 */
472
473#define TNC_UNINITIALIZED 0
474#define TNC_UNSYNC_STARTUP 1
475#define TNC_UNSYNCED 2
476#define TNC_IN_SYNC 3
477
478static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
479{
480 char *msg;
481
482 switch (new_tnc_state) {
483 default: /* gcc oh piece-o-crap ... */
484 case TNC_UNSYNC_STARTUP:
485 msg = "Synchronizing with TNC";
486 break;
487 case TNC_UNSYNCED:
488 msg = "Lost synchronization with TNC\n";
489 break;
490 case TNC_IN_SYNC:
491 msg = "Found TNC";
492 break;
493 }
494
495 sp->tnc_state = new_tnc_state;
496 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
497}
498
499static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
500{
501 int old_tnc_state = sp->tnc_state;
502
503 if (old_tnc_state != new_tnc_state)
504 __tnc_set_sync_state(sp, new_tnc_state);
505}
506
507static void resync_tnc(unsigned long channel)
508{
509 struct sixpack *sp = (struct sixpack *) channel;
510 static char resync_cmd = 0xe8;
511
512 /* clear any data that might have been received */
513
514 sp->rx_count = 0;
515 sp->rx_count_cooked = 0;
516
517 /* reset state machine */
518
519 sp->status = 1;
520 sp->status1 = 1;
521 sp->status2 = 0;
522
523 /* resync the TNC */
524
525 sp->led_state = 0x60;
526 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
527 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
528
529
530 /* Start resync timer again -- the TNC might be still absent */
531
532 del_timer(&sp->resync_t);
533 sp->resync_t.data = (unsigned long) sp;
534 sp->resync_t.function = resync_tnc;
535 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
536 add_timer(&sp->resync_t);
537}
538
539static inline int tnc_init(struct sixpack *sp)
540{
541 unsigned char inbyte = 0xe8;
542
543 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
544
545 sp->tty->ops->write(sp->tty, &inbyte, 1);
546
547 del_timer(&sp->resync_t);
548 sp->resync_t.data = (unsigned long) sp;
549 sp->resync_t.function = resync_tnc;
550 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
551 add_timer(&sp->resync_t);
552
553 return 0;
554}
555
556/*
557 * Open the high-level part of the 6pack channel.
558 * This function is called by the TTY module when the
559 * 6pack line discipline is called for. Because we are
560 * sure the tty line exists, we only have to link it to
561 * a free 6pcack channel...
562 */
563static int sixpack_open(struct tty_struct *tty)
564{
565 char *rbuff = NULL, *xbuff = NULL;
566 struct net_device *dev;
567 struct sixpack *sp;
568 unsigned long len;
569 int err = 0;
570
571 if (!capable(CAP_NET_ADMIN))
572 return -EPERM;
573 if (tty->ops->write == NULL)
574 return -EOPNOTSUPP;
575
576 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
577 sp_setup);
578 if (!dev) {
579 err = -ENOMEM;
580 goto out;
581 }
582
583 sp = netdev_priv(dev);
584 sp->dev = dev;
585
586 spin_lock_init(&sp->lock);
587 atomic_set(&sp->refcnt, 1);
588 sema_init(&sp->dead_sem, 0);
589
590 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
591
592 len = dev->mtu * 2;
593
594 rbuff = kmalloc(len + 4, GFP_KERNEL);
595 xbuff = kmalloc(len + 4, GFP_KERNEL);
596
597 if (rbuff == NULL || xbuff == NULL) {
598 err = -ENOBUFS;
599 goto out_free;
600 }
601
602 spin_lock_bh(&sp->lock);
603
604 sp->tty = tty;
605
606 sp->rbuff = rbuff;
607 sp->xbuff = xbuff;
608
609 sp->mtu = AX25_MTU + 73;
610 sp->buffsize = len;
611 sp->rcount = 0;
612 sp->rx_count = 0;
613 sp->rx_count_cooked = 0;
614 sp->xleft = 0;
615
616 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
617
618 sp->duplex = 0;
619 sp->tx_delay = SIXP_TXDELAY;
620 sp->persistence = SIXP_PERSIST;
621 sp->slottime = SIXP_SLOTTIME;
622 sp->led_state = 0x60;
623 sp->status = 1;
624 sp->status1 = 1;
625 sp->status2 = 0;
626 sp->tx_enable = 0;
627
628 netif_start_queue(dev);
629
630 init_timer(&sp->tx_t);
631 sp->tx_t.function = sp_xmit_on_air;
632 sp->tx_t.data = (unsigned long) sp;
633
634 init_timer(&sp->resync_t);
635
636 spin_unlock_bh(&sp->lock);
637
638 /* Done. We have linked the TTY line to a channel. */
639 tty->disc_data = sp;
640 tty->receive_room = 65536;
641
642 /* Now we're ready to register. */
643 err = register_netdev(dev);
644 if (err)
645 goto out_free;
646
647 tnc_init(sp);
648
649 return 0;
650
651out_free:
652 kfree(xbuff);
653 kfree(rbuff);
654
655 free_netdev(dev);
656
657out:
658 return err;
659}
660
661
662/*
663 * Close down a 6pack channel.
664 * This means flushing out any pending queues, and then restoring the
665 * TTY line discipline to what it was before it got hooked to 6pack
666 * (which usually is TTY again).
667 */
668static void sixpack_close(struct tty_struct *tty)
669{
670 struct sixpack *sp;
671
672 write_lock_bh(&disc_data_lock);
673 sp = tty->disc_data;
674 tty->disc_data = NULL;
675 write_unlock_bh(&disc_data_lock);
676 if (!sp)
677 return;
678
679 /*
680 * We have now ensured that nobody can start using ap from now on, but
681 * we have to wait for all existing users to finish.
682 */
683 if (!atomic_dec_and_test(&sp->refcnt))
684 down(&sp->dead_sem);
685
686 /* We must stop the queue to avoid potentially scribbling
687 * on the free buffers. The sp->dead_sem is not sufficient
688 * to protect us from sp->xbuff access.
689 */
690 netif_stop_queue(sp->dev);
691
692 del_timer_sync(&sp->tx_t);
693 del_timer_sync(&sp->resync_t);
694
695 /* Free all 6pack frame buffers. */
696 kfree(sp->rbuff);
697 kfree(sp->xbuff);
698
699 unregister_netdev(sp->dev);
700}
701
702/* Perform I/O control on an active 6pack channel. */
703static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
704 unsigned int cmd, unsigned long arg)
705{
706 struct sixpack *sp = sp_get(tty);
707 struct net_device *dev;
708 unsigned int tmp, err;
709
710 if (!sp)
711 return -ENXIO;
712 dev = sp->dev;
713
714 switch(cmd) {
715 case SIOCGIFNAME:
716 err = copy_to_user((void __user *) arg, dev->name,
717 strlen(dev->name) + 1) ? -EFAULT : 0;
718 break;
719
720 case SIOCGIFENCAP:
721 err = put_user(0, (int __user *) arg);
722 break;
723
724 case SIOCSIFENCAP:
725 if (get_user(tmp, (int __user *) arg)) {
726 err = -EFAULT;
727 break;
728 }
729
730 sp->mode = tmp;
731 dev->addr_len = AX25_ADDR_LEN;
732 dev->hard_header_len = AX25_KISS_HEADER_LEN +
733 AX25_MAX_HEADER_LEN + 3;
734 dev->type = ARPHRD_AX25;
735
736 err = 0;
737 break;
738
739 case SIOCSIFHWADDR: {
740 char addr[AX25_ADDR_LEN];
741
742 if (copy_from_user(&addr,
743 (void __user *) arg, AX25_ADDR_LEN)) {
744 err = -EFAULT;
745 break;
746 }
747
748 netif_tx_lock_bh(dev);
749 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
750 netif_tx_unlock_bh(dev);
751
752 err = 0;
753 break;
754 }
755
756 default:
757 err = tty_mode_ioctl(tty, file, cmd, arg);
758 }
759
760 sp_put(sp);
761
762 return err;
763}
764
765#ifdef CONFIG_COMPAT
766static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
767 unsigned int cmd, unsigned long arg)
768{
769 switch (cmd) {
770 case SIOCGIFNAME:
771 case SIOCGIFENCAP:
772 case SIOCSIFENCAP:
773 case SIOCSIFHWADDR:
774 return sixpack_ioctl(tty, file, cmd,
775 (unsigned long)compat_ptr(arg));
776 }
777
778 return -ENOIOCTLCMD;
779}
780#endif
781
782static struct tty_ldisc_ops sp_ldisc = {
783 .owner = THIS_MODULE,
784 .magic = TTY_LDISC_MAGIC,
785 .name = "6pack",
786 .open = sixpack_open,
787 .close = sixpack_close,
788 .ioctl = sixpack_ioctl,
789#ifdef CONFIG_COMPAT
790 .compat_ioctl = sixpack_compat_ioctl,
791#endif
792 .receive_buf = sixpack_receive_buf,
793 .write_wakeup = sixpack_write_wakeup,
794};
795
796/* Initialize 6pack control device -- register 6pack line discipline */
797
798static const char msg_banner[] __initconst = KERN_INFO \
799 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
800static const char msg_regfail[] __initconst = KERN_ERR \
801 "6pack: can't register line discipline (err = %d)\n";
802
803static int __init sixpack_init_driver(void)
804{
805 int status;
806
807 printk(msg_banner);
808
809 /* Register the provided line protocol discipline */
810 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
811 printk(msg_regfail, status);
812
813 return status;
814}
815
816static const char msg_unregfail[] = KERN_ERR \
817 "6pack: can't unregister line discipline (err = %d)\n";
818
819static void __exit sixpack_exit_driver(void)
820{
821 int ret;
822
823 if ((ret = tty_unregister_ldisc(N_6PACK)))
824 printk(msg_unregfail, ret);
825}
826
827/* encode an AX.25 packet into 6pack */
828
829static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
830 int length, unsigned char tx_delay)
831{
832 int count = 0;
833 unsigned char checksum = 0, buf[400];
834 int raw_count = 0;
835
836 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
837 tx_buf_raw[raw_count++] = SIXP_SEOF;
838
839 buf[0] = tx_delay;
840 for (count = 1; count < length; count++)
841 buf[count] = tx_buf[count];
842
843 for (count = 0; count < length; count++)
844 checksum += buf[count];
845 buf[length] = (unsigned char) 0xff - checksum;
846
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);
854 } else {
855 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
856 tx_buf_raw[raw_count++] = (buf[count] >> 2);
857 }
858 }
859 if ((length % 3) != 2)
860 raw_count++;
861 tx_buf_raw[raw_count++] = SIXP_SEOF;
862 return raw_count;
863}
864
865/* decode 4 sixpack-encoded bytes into 3 data bytes */
866
867static void decode_data(struct sixpack *sp, unsigned char inbyte)
868{
869 unsigned char *buf;
870
871 if (sp->rx_count != 3) {
872 sp->raw_buf[sp->rx_count++] = inbyte;
873
874 return;
875 }
876
877 buf = sp->raw_buf;
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);
884 sp->rx_count = 0;
885}
886
887/* identify and execute a 6pack priority command byte */
888
889static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
890{
891 unsigned char channel;
892 int actual;
893
894 channel = cmd & SIXP_CHN_MASK;
895 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
896
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. */
903
904 if (((sp->status & SIXP_DCD_MASK) == 0) &&
905 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
906 if (sp->status != 1)
907 printk(KERN_DEBUG "6pack: protocol violation\n");
908 else
909 sp->status = 0;
910 cmd &= ~SIXP_RX_DCD_MASK;
911 }
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->ops->write(sp->tty, &sp->led_state, 1);
917 sp->tx_enable = 1;
918 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
919 sp->xleft -= actual;
920 sp->xhead += actual;
921 sp->led_state = 0x60;
922 sp->status2 = 0;
923
924 }
925 }
926
927 /* needed to trigger the TNC watchdog */
928 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
929
930 /* if the state byte has been received, the TNC is present,
931 so the resync timer can be reset. */
932
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);
939 }
940
941 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
942}
943
944/* identify and execute a standard 6pack command byte */
945
946static void decode_std_command(struct sixpack *sp, unsigned char cmd)
947{
948 unsigned char checksum = 0, rest = 0, channel;
949 short i;
950
951 channel = cmd & SIXP_CHN_MASK;
952 switch (cmd & SIXP_CMD_MASK) { /* normal command */
953 case SIXP_SEOF:
954 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
955 if ((sp->status & SIXP_RX_DCD_MASK) ==
956 SIXP_RX_DCD_MASK) {
957 sp->led_state = 0x68;
958 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
959 }
960 } else {
961 sp->led_state = 0x60;
962 /* fill trailing bytes with zeroes */
963 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
964 rest = sp->rx_count;
965 if (rest != 0)
966 for (i = rest; i <= 3; i++)
967 decode_data(sp, 0);
968 if (rest == 2)
969 sp->rx_count_cooked -= 2;
970 else if (rest == 3)
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);
976 } else {
977 sp->rcount = sp->rx_count_cooked-2;
978 sp_bump(sp, 0);
979 }
980 sp->rx_count_cooked = 0;
981 }
982 break;
983 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
984 break;
985 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
986 break;
987 case SIXP_RX_BUF_OVL:
988 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
989 }
990}
991
992/* decode a 6pack packet */
993
994static void
995sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
996{
997 unsigned char inbyte;
998 int count1;
999
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);
1005 }
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);
1012 }
1013}
1014
1015MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1016MODULE_DESCRIPTION("6pack driver for AX.25");
1017MODULE_LICENSE("GPL");
1018MODULE_ALIAS_LDISC(N_6PACK);
1019
1020module_init(sixpack_init_driver);
1021module_exit(sixpack_exit_driver);