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
81 enum sixpack_flags {
82 SIXPF_ERROR, /* Parity, etc. error */
83 };
84
85 struct 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
130 static void sixpack_decode(struct sixpack *, unsigned char[], int);
131 static 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
sp_xmit_on_air(unsigned long channel)139 static 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. */
sp_encaps(struct sixpack * sp,unsigned char * icp,int len)164 static 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
237 out_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
sp_xmit(struct sk_buff * skb,struct net_device * dev)246 static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
247 {
248 struct sixpack *sp = netdev_priv(dev);
249
250 spin_lock_bh(&sp->lock);
251 /* We were not busy, so we are now... :-) */
252 netif_stop_queue(dev);
253 dev->stats.tx_bytes += skb->len;
254 sp_encaps(sp, skb->data, skb->len);
255 spin_unlock_bh(&sp->lock);
256
257 dev_kfree_skb(skb);
258
259 return NETDEV_TX_OK;
260 }
261
sp_open_dev(struct net_device * dev)262 static int sp_open_dev(struct net_device *dev)
263 {
264 struct sixpack *sp = netdev_priv(dev);
265
266 if (sp->tty == NULL)
267 return -ENODEV;
268 return 0;
269 }
270
271 /* Close the low-level part of the 6pack channel. */
sp_close(struct net_device * dev)272 static int sp_close(struct net_device *dev)
273 {
274 struct sixpack *sp = netdev_priv(dev);
275
276 spin_lock_bh(&sp->lock);
277 if (sp->tty) {
278 /* TTY discipline is running. */
279 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
280 }
281 netif_stop_queue(dev);
282 spin_unlock_bh(&sp->lock);
283
284 return 0;
285 }
286
287 /* Return the frame type ID */
sp_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,const void * daddr,const void * saddr,unsigned len)288 static int sp_header(struct sk_buff *skb, struct net_device *dev,
289 unsigned short type, const void *daddr,
290 const void *saddr, unsigned len)
291 {
292 #ifdef CONFIG_INET
293 if (type != ETH_P_AX25)
294 return ax25_hard_header(skb, dev, type, daddr, saddr, len);
295 #endif
296 return 0;
297 }
298
sp_set_mac_address(struct net_device * dev,void * addr)299 static int sp_set_mac_address(struct net_device *dev, void *addr)
300 {
301 struct sockaddr_ax25 *sa = addr;
302
303 netif_tx_lock_bh(dev);
304 netif_addr_lock(dev);
305 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
306 netif_addr_unlock(dev);
307 netif_tx_unlock_bh(dev);
308
309 return 0;
310 }
311
sp_rebuild_header(struct sk_buff * skb)312 static int sp_rebuild_header(struct sk_buff *skb)
313 {
314 #ifdef CONFIG_INET
315 return ax25_rebuild_header(skb);
316 #else
317 return 0;
318 #endif
319 }
320
321 static const struct header_ops sp_header_ops = {
322 .create = sp_header,
323 .rebuild = sp_rebuild_header,
324 };
325
326 static const struct net_device_ops sp_netdev_ops = {
327 .ndo_open = sp_open_dev,
328 .ndo_stop = sp_close,
329 .ndo_start_xmit = sp_xmit,
330 .ndo_set_mac_address = sp_set_mac_address,
331 };
332
sp_setup(struct net_device * dev)333 static void sp_setup(struct net_device *dev)
334 {
335 /* Finish setting up the DEVICE info. */
336 dev->netdev_ops = &sp_netdev_ops;
337 dev->destructor = free_netdev;
338 dev->mtu = SIXP_MTU;
339 dev->hard_header_len = AX25_MAX_HEADER_LEN;
340 dev->header_ops = &sp_header_ops;
341
342 dev->addr_len = AX25_ADDR_LEN;
343 dev->type = ARPHRD_AX25;
344 dev->tx_queue_len = 10;
345
346 /* Only activated in AX.25 mode */
347 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
348 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
349
350 dev->flags = 0;
351 }
352
353 /* Send one completely decapsulated IP datagram to the IP layer. */
354
355 /*
356 * This is the routine that sends the received data to the kernel AX.25.
357 * 'cmd' is the KISS command. For AX.25 data, it is zero.
358 */
359
sp_bump(struct sixpack * sp,char cmd)360 static void sp_bump(struct sixpack *sp, char cmd)
361 {
362 struct sk_buff *skb;
363 int count;
364 unsigned char *ptr;
365
366 count = sp->rcount + 1;
367
368 sp->dev->stats.rx_bytes += count;
369
370 if ((skb = dev_alloc_skb(count)) == NULL)
371 goto out_mem;
372
373 ptr = skb_put(skb, count);
374 *ptr++ = cmd; /* KISS command */
375
376 memcpy(ptr, sp->cooked_buf + 1, count);
377 skb->protocol = ax25_type_trans(skb, sp->dev);
378 netif_rx(skb);
379 sp->dev->stats.rx_packets++;
380
381 return;
382
383 out_mem:
384 sp->dev->stats.rx_dropped++;
385 }
386
387
388 /* ----------------------------------------------------------------------- */
389
390 /*
391 * We have a potential race on dereferencing tty->disc_data, because the tty
392 * layer provides no locking at all - thus one cpu could be running
393 * sixpack_receive_buf while another calls sixpack_close, which zeroes
394 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
395 * best way to fix this is to use a rwlock in the tty struct, but for now we
396 * use a single global rwlock for all ttys in ppp line discipline.
397 */
398 static DEFINE_RWLOCK(disc_data_lock);
399
sp_get(struct tty_struct * tty)400 static struct sixpack *sp_get(struct tty_struct *tty)
401 {
402 struct sixpack *sp;
403
404 read_lock(&disc_data_lock);
405 sp = tty->disc_data;
406 if (sp)
407 atomic_inc(&sp->refcnt);
408 read_unlock(&disc_data_lock);
409
410 return sp;
411 }
412
sp_put(struct sixpack * sp)413 static void sp_put(struct sixpack *sp)
414 {
415 if (atomic_dec_and_test(&sp->refcnt))
416 up(&sp->dead_sem);
417 }
418
419 /*
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.
422 */
sixpack_write_wakeup(struct tty_struct * tty)423 static void sixpack_write_wakeup(struct tty_struct *tty)
424 {
425 struct sixpack *sp = sp_get(tty);
426 int actual;
427
428 if (!sp)
429 return;
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);
435 sp->tx_enable = 0;
436 netif_wake_queue(sp->dev);
437 goto out;
438 }
439
440 if (sp->tx_enable) {
441 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
442 sp->xleft -= actual;
443 sp->xhead += actual;
444 }
445
446 out:
447 sp_put(sp);
448 }
449
450 /* ----------------------------------------------------------------------- */
451
452 /*
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.
457 */
sixpack_receive_buf(struct tty_struct * tty,const unsigned char * cp,char * fp,int count)458 static void sixpack_receive_buf(struct tty_struct *tty,
459 const unsigned char *cp, char *fp, int count)
460 {
461 struct sixpack *sp;
462 unsigned char buf[512];
463 int count1;
464
465 if (!count)
466 return;
467
468 sp = sp_get(tty);
469 if (!sp)
470 return;
471
472 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
473
474 /* Read the characters out of the buffer */
475
476 count1 = count;
477 while (count) {
478 count--;
479 if (fp && *fp++) {
480 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
481 sp->dev->stats.rx_errors++;
482 continue;
483 }
484 }
485 sixpack_decode(sp, buf, count1);
486
487 sp_put(sp);
488 tty_unthrottle(tty);
489 }
490
491 /*
492 * Try to resync the TNC. Called by the resync timer defined in
493 * decode_prio_command
494 */
495
496 #define TNC_UNINITIALIZED 0
497 #define TNC_UNSYNC_STARTUP 1
498 #define TNC_UNSYNCED 2
499 #define TNC_IN_SYNC 3
500
__tnc_set_sync_state(struct sixpack * sp,int new_tnc_state)501 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
502 {
503 char *msg;
504
505 switch (new_tnc_state) {
506 default: /* gcc oh piece-o-crap ... */
507 case TNC_UNSYNC_STARTUP:
508 msg = "Synchronizing with TNC";
509 break;
510 case TNC_UNSYNCED:
511 msg = "Lost synchronization with TNC\n";
512 break;
513 case TNC_IN_SYNC:
514 msg = "Found TNC";
515 break;
516 }
517
518 sp->tnc_state = new_tnc_state;
519 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
520 }
521
tnc_set_sync_state(struct sixpack * sp,int new_tnc_state)522 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
523 {
524 int old_tnc_state = sp->tnc_state;
525
526 if (old_tnc_state != new_tnc_state)
527 __tnc_set_sync_state(sp, new_tnc_state);
528 }
529
resync_tnc(unsigned long channel)530 static void resync_tnc(unsigned long channel)
531 {
532 struct sixpack *sp = (struct sixpack *) channel;
533 static char resync_cmd = 0xe8;
534
535 /* clear any data that might have been received */
536
537 sp->rx_count = 0;
538 sp->rx_count_cooked = 0;
539
540 /* reset state machine */
541
542 sp->status = 1;
543 sp->status1 = 1;
544 sp->status2 = 0;
545
546 /* resync the TNC */
547
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);
551
552
553 /* Start resync timer again -- the TNC might be still absent */
554
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);
560 }
561
tnc_init(struct sixpack * sp)562 static inline int tnc_init(struct sixpack *sp)
563 {
564 unsigned char inbyte = 0xe8;
565
566 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
567
568 sp->tty->ops->write(sp->tty, &inbyte, 1);
569
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);
575
576 return 0;
577 }
578
579 /*
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...
585 */
sixpack_open(struct tty_struct * tty)586 static int sixpack_open(struct tty_struct *tty)
587 {
588 char *rbuff = NULL, *xbuff = NULL;
589 struct net_device *dev;
590 struct sixpack *sp;
591 unsigned long len;
592 int err = 0;
593
594 if (!capable(CAP_NET_ADMIN))
595 return -EPERM;
596 if (tty->ops->write == NULL)
597 return -EOPNOTSUPP;
598
599 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
600 sp_setup);
601 if (!dev) {
602 err = -ENOMEM;
603 goto out;
604 }
605
606 sp = netdev_priv(dev);
607 sp->dev = dev;
608
609 spin_lock_init(&sp->lock);
610 atomic_set(&sp->refcnt, 1);
611 sema_init(&sp->dead_sem, 0);
612
613 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
614
615 len = dev->mtu * 2;
616
617 rbuff = kmalloc(len + 4, GFP_KERNEL);
618 xbuff = kmalloc(len + 4, GFP_KERNEL);
619
620 if (rbuff == NULL || xbuff == NULL) {
621 err = -ENOBUFS;
622 goto out_free;
623 }
624
625 spin_lock_bh(&sp->lock);
626
627 sp->tty = tty;
628
629 sp->rbuff = rbuff;
630 sp->xbuff = xbuff;
631
632 sp->mtu = AX25_MTU + 73;
633 sp->buffsize = len;
634 sp->rcount = 0;
635 sp->rx_count = 0;
636 sp->rx_count_cooked = 0;
637 sp->xleft = 0;
638
639 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
640
641 sp->duplex = 0;
642 sp->tx_delay = SIXP_TXDELAY;
643 sp->persistence = SIXP_PERSIST;
644 sp->slottime = SIXP_SLOTTIME;
645 sp->led_state = 0x60;
646 sp->status = 1;
647 sp->status1 = 1;
648 sp->status2 = 0;
649 sp->tx_enable = 0;
650
651 netif_start_queue(dev);
652
653 init_timer(&sp->tx_t);
654 sp->tx_t.function = sp_xmit_on_air;
655 sp->tx_t.data = (unsigned long) sp;
656
657 init_timer(&sp->resync_t);
658
659 spin_unlock_bh(&sp->lock);
660
661 /* Done. We have linked the TTY line to a channel. */
662 tty->disc_data = sp;
663 tty->receive_room = 65536;
664
665 /* Now we're ready to register. */
666 err = register_netdev(dev);
667 if (err)
668 goto out_free;
669
670 tnc_init(sp);
671
672 return 0;
673
674 out_free:
675 kfree(xbuff);
676 kfree(rbuff);
677
678 if (dev)
679 free_netdev(dev);
680
681 out:
682 return err;
683 }
684
685
686 /*
687 * Close down a 6pack channel.
688 * This means flushing out any pending queues, and then restoring the
689 * TTY line discipline to what it was before it got hooked to 6pack
690 * (which usually is TTY again).
691 */
sixpack_close(struct tty_struct * tty)692 static void sixpack_close(struct tty_struct *tty)
693 {
694 struct sixpack *sp;
695
696 write_lock_bh(&disc_data_lock);
697 sp = tty->disc_data;
698 tty->disc_data = NULL;
699 write_unlock_bh(&disc_data_lock);
700 if (!sp)
701 return;
702
703 /*
704 * We have now ensured that nobody can start using ap from now on, but
705 * we have to wait for all existing users to finish.
706 */
707 if (!atomic_dec_and_test(&sp->refcnt))
708 down(&sp->dead_sem);
709
710 unregister_netdev(sp->dev);
711
712 del_timer(&sp->tx_t);
713 del_timer(&sp->resync_t);
714
715 /* Free all 6pack frame buffers. */
716 kfree(sp->rbuff);
717 kfree(sp->xbuff);
718 }
719
720 /* Perform I/O control on an active 6pack channel. */
sixpack_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)721 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
722 unsigned int cmd, unsigned long arg)
723 {
724 struct sixpack *sp = sp_get(tty);
725 struct net_device *dev;
726 unsigned int tmp, err;
727
728 if (!sp)
729 return -ENXIO;
730 dev = sp->dev;
731
732 switch(cmd) {
733 case SIOCGIFNAME:
734 err = copy_to_user((void __user *) arg, dev->name,
735 strlen(dev->name) + 1) ? -EFAULT : 0;
736 break;
737
738 case SIOCGIFENCAP:
739 err = put_user(0, (int __user *) arg);
740 break;
741
742 case SIOCSIFENCAP:
743 if (get_user(tmp, (int __user *) arg)) {
744 err = -EFAULT;
745 break;
746 }
747
748 sp->mode = tmp;
749 dev->addr_len = AX25_ADDR_LEN;
750 dev->hard_header_len = AX25_KISS_HEADER_LEN +
751 AX25_MAX_HEADER_LEN + 3;
752 dev->type = ARPHRD_AX25;
753
754 err = 0;
755 break;
756
757 case SIOCSIFHWADDR: {
758 char addr[AX25_ADDR_LEN];
759
760 if (copy_from_user(&addr,
761 (void __user *) arg, AX25_ADDR_LEN)) {
762 err = -EFAULT;
763 break;
764 }
765
766 netif_tx_lock_bh(dev);
767 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
768 netif_tx_unlock_bh(dev);
769
770 err = 0;
771 break;
772 }
773
774 default:
775 err = tty_mode_ioctl(tty, file, cmd, arg);
776 }
777
778 sp_put(sp);
779
780 return err;
781 }
782
783 #ifdef CONFIG_COMPAT
sixpack_compat_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)784 static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
785 unsigned int cmd, unsigned long arg)
786 {
787 switch (cmd) {
788 case SIOCGIFNAME:
789 case SIOCGIFENCAP:
790 case SIOCSIFENCAP:
791 case SIOCSIFHWADDR:
792 return sixpack_ioctl(tty, file, cmd,
793 (unsigned long)compat_ptr(arg));
794 }
795
796 return -ENOIOCTLCMD;
797 }
798 #endif
799
800 static struct tty_ldisc_ops sp_ldisc = {
801 .owner = THIS_MODULE,
802 .magic = TTY_LDISC_MAGIC,
803 .name = "6pack",
804 .open = sixpack_open,
805 .close = sixpack_close,
806 .ioctl = sixpack_ioctl,
807 #ifdef CONFIG_COMPAT
808 .compat_ioctl = sixpack_compat_ioctl,
809 #endif
810 .receive_buf = sixpack_receive_buf,
811 .write_wakeup = sixpack_write_wakeup,
812 };
813
814 /* Initialize 6pack control device -- register 6pack line discipline */
815
816 static const char msg_banner[] __initconst = KERN_INFO \
817 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
818 static const char msg_regfail[] __initconst = KERN_ERR \
819 "6pack: can't register line discipline (err = %d)\n";
820
sixpack_init_driver(void)821 static int __init sixpack_init_driver(void)
822 {
823 int status;
824
825 printk(msg_banner);
826
827 /* Register the provided line protocol discipline */
828 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
829 printk(msg_regfail, status);
830
831 return status;
832 }
833
834 static const char msg_unregfail[] = KERN_ERR \
835 "6pack: can't unregister line discipline (err = %d)\n";
836
sixpack_exit_driver(void)837 static void __exit sixpack_exit_driver(void)
838 {
839 int ret;
840
841 if ((ret = tty_unregister_ldisc(N_6PACK)))
842 printk(msg_unregfail, ret);
843 }
844
845 /* encode an AX.25 packet into 6pack */
846
encode_sixpack(unsigned char * tx_buf,unsigned char * tx_buf_raw,int length,unsigned char tx_delay)847 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
848 int length, unsigned char tx_delay)
849 {
850 int count = 0;
851 unsigned char checksum = 0, buf[400];
852 int raw_count = 0;
853
854 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
855 tx_buf_raw[raw_count++] = SIXP_SEOF;
856
857 buf[0] = tx_delay;
858 for (count = 1; count < length; count++)
859 buf[count] = tx_buf[count];
860
861 for (count = 0; count < length; count++)
862 checksum += buf[count];
863 buf[length] = (unsigned char) 0xff - checksum;
864
865 for (count = 0; count <= length; count++) {
866 if ((count % 3) == 0) {
867 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
868 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
869 } else if ((count % 3) == 1) {
870 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
871 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
872 } else {
873 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
874 tx_buf_raw[raw_count++] = (buf[count] >> 2);
875 }
876 }
877 if ((length % 3) != 2)
878 raw_count++;
879 tx_buf_raw[raw_count++] = SIXP_SEOF;
880 return raw_count;
881 }
882
883 /* decode 4 sixpack-encoded bytes into 3 data bytes */
884
decode_data(struct sixpack * sp,unsigned char inbyte)885 static void decode_data(struct sixpack *sp, unsigned char inbyte)
886 {
887 unsigned char *buf;
888
889 if (sp->rx_count != 3) {
890 sp->raw_buf[sp->rx_count++] = inbyte;
891
892 return;
893 }
894
895 buf = sp->raw_buf;
896 sp->cooked_buf[sp->rx_count_cooked++] =
897 buf[0] | ((buf[1] << 2) & 0xc0);
898 sp->cooked_buf[sp->rx_count_cooked++] =
899 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
900 sp->cooked_buf[sp->rx_count_cooked++] =
901 (buf[2] & 0x03) | (inbyte << 2);
902 sp->rx_count = 0;
903 }
904
905 /* identify and execute a 6pack priority command byte */
906
decode_prio_command(struct sixpack * sp,unsigned char cmd)907 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
908 {
909 unsigned char channel;
910 int actual;
911
912 channel = cmd & SIXP_CHN_MASK;
913 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
914
915 /* RX and DCD flags can only be set in the same prio command,
916 if the DCD flag has been set without the RX flag in the previous
917 prio command. If DCD has not been set before, something in the
918 transmission has gone wrong. In this case, RX and DCD are
919 cleared in order to prevent the decode_data routine from
920 reading further data that might be corrupt. */
921
922 if (((sp->status & SIXP_DCD_MASK) == 0) &&
923 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
924 if (sp->status != 1)
925 printk(KERN_DEBUG "6pack: protocol violation\n");
926 else
927 sp->status = 0;
928 cmd &= ~SIXP_RX_DCD_MASK;
929 }
930 sp->status = cmd & SIXP_PRIO_DATA_MASK;
931 } else { /* output watchdog char if idle */
932 if ((sp->status2 != 0) && (sp->duplex == 1)) {
933 sp->led_state = 0x70;
934 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
935 sp->tx_enable = 1;
936 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
937 sp->xleft -= actual;
938 sp->xhead += actual;
939 sp->led_state = 0x60;
940 sp->status2 = 0;
941
942 }
943 }
944
945 /* needed to trigger the TNC watchdog */
946 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
947
948 /* if the state byte has been received, the TNC is present,
949 so the resync timer can be reset. */
950
951 if (sp->tnc_state == TNC_IN_SYNC) {
952 del_timer(&sp->resync_t);
953 sp->resync_t.data = (unsigned long) sp;
954 sp->resync_t.function = resync_tnc;
955 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
956 add_timer(&sp->resync_t);
957 }
958
959 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
960 }
961
962 /* identify and execute a standard 6pack command byte */
963
decode_std_command(struct sixpack * sp,unsigned char cmd)964 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
965 {
966 unsigned char checksum = 0, rest = 0, channel;
967 short i;
968
969 channel = cmd & SIXP_CHN_MASK;
970 switch (cmd & SIXP_CMD_MASK) { /* normal command */
971 case SIXP_SEOF:
972 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
973 if ((sp->status & SIXP_RX_DCD_MASK) ==
974 SIXP_RX_DCD_MASK) {
975 sp->led_state = 0x68;
976 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
977 }
978 } else {
979 sp->led_state = 0x60;
980 /* fill trailing bytes with zeroes */
981 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
982 rest = sp->rx_count;
983 if (rest != 0)
984 for (i = rest; i <= 3; i++)
985 decode_data(sp, 0);
986 if (rest == 2)
987 sp->rx_count_cooked -= 2;
988 else if (rest == 3)
989 sp->rx_count_cooked -= 1;
990 for (i = 0; i < sp->rx_count_cooked; i++)
991 checksum += sp->cooked_buf[i];
992 if (checksum != SIXP_CHKSUM) {
993 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
994 } else {
995 sp->rcount = sp->rx_count_cooked-2;
996 sp_bump(sp, 0);
997 }
998 sp->rx_count_cooked = 0;
999 }
1000 break;
1001 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
1002 break;
1003 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
1004 break;
1005 case SIXP_RX_BUF_OVL:
1006 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
1007 }
1008 }
1009
1010 /* decode a 6pack packet */
1011
1012 static void
sixpack_decode(struct sixpack * sp,unsigned char * pre_rbuff,int count)1013 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
1014 {
1015 unsigned char inbyte;
1016 int count1;
1017
1018 for (count1 = 0; count1 < count; count1++) {
1019 inbyte = pre_rbuff[count1];
1020 if (inbyte == SIXP_FOUND_TNC) {
1021 tnc_set_sync_state(sp, TNC_IN_SYNC);
1022 del_timer(&sp->resync_t);
1023 }
1024 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1025 decode_prio_command(sp, inbyte);
1026 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1027 decode_std_command(sp, inbyte);
1028 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1029 decode_data(sp, inbyte);
1030 }
1031 }
1032
1033 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1034 MODULE_DESCRIPTION("6pack driver for AX.25");
1035 MODULE_LICENSE("GPL");
1036 MODULE_ALIAS_LDISC(N_6PACK);
1037
1038 module_init(sixpack_init_driver);
1039 module_exit(sixpack_exit_driver);
1040