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/refcount.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 refcount_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 *, const 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(struct timer_list * t)139 static void sp_xmit_on_air(struct timer_list *t)
140 {
141 struct sixpack *sp = from_timer(sp, t, tx_t);
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(&sp->tx_t);
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 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
sp_open_dev(struct net_device * dev)265 static 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. */
sp_close(struct net_device * dev)275 static 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
sp_set_mac_address(struct net_device * dev,void * addr)290 static 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
303 static 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
sp_setup(struct net_device * dev)310 static void sp_setup(struct net_device *dev)
311 {
312 /* Finish setting up the DEVICE info. */
313 dev->netdev_ops = &sp_netdev_ops;
314 dev->needs_free_netdev = true;
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
sp_bump(struct sixpack * sp,char cmd)337 static 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
360 out_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 */
375 static DEFINE_RWLOCK(disc_data_lock);
376
sp_get(struct tty_struct * tty)377 static 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 refcount_inc(&sp->refcnt);
385 read_unlock(&disc_data_lock);
386
387 return sp;
388 }
389
sp_put(struct sixpack * sp)390 static void sp_put(struct sixpack *sp)
391 {
392 if (refcount_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 */
sixpack_write_wakeup(struct tty_struct * tty)400 static 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
423 out:
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 */
sixpack_receive_buf(struct tty_struct * tty,const unsigned char * cp,char * fp,int count)435 static 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
__tnc_set_sync_state(struct sixpack * sp,int new_tnc_state)474 static 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
tnc_set_sync_state(struct sixpack * sp,int new_tnc_state)495 static 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
resync_tnc(struct timer_list * t)503 static void resync_tnc(struct timer_list *t)
504 {
505 struct sixpack *sp = from_timer(sp, t, resync_t);
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.expires = jiffies + SIXP_RESYNC_TIMEOUT;
530 add_timer(&sp->resync_t);
531 }
532
tnc_init(struct sixpack * sp)533 static inline int tnc_init(struct sixpack *sp)
534 {
535 unsigned char inbyte = 0xe8;
536
537 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
538
539 sp->tty->ops->write(sp->tty, &inbyte, 1);
540
541 del_timer(&sp->resync_t);
542 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
543 add_timer(&sp->resync_t);
544
545 return 0;
546 }
547
548 /*
549 * Open the high-level part of the 6pack channel.
550 * This function is called by the TTY module when the
551 * 6pack line discipline is called for. Because we are
552 * sure the tty line exists, we only have to link it to
553 * a free 6pcack channel...
554 */
sixpack_open(struct tty_struct * tty)555 static int sixpack_open(struct tty_struct *tty)
556 {
557 char *rbuff = NULL, *xbuff = NULL;
558 struct net_device *dev;
559 struct sixpack *sp;
560 unsigned long len;
561 int err = 0;
562
563 if (!capable(CAP_NET_ADMIN))
564 return -EPERM;
565 if (tty->ops->write == NULL)
566 return -EOPNOTSUPP;
567
568 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
569 sp_setup);
570 if (!dev) {
571 err = -ENOMEM;
572 goto out;
573 }
574
575 sp = netdev_priv(dev);
576 sp->dev = dev;
577
578 spin_lock_init(&sp->lock);
579 refcount_set(&sp->refcnt, 1);
580 sema_init(&sp->dead_sem, 0);
581
582 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
583
584 len = dev->mtu * 2;
585
586 rbuff = kmalloc(len + 4, GFP_KERNEL);
587 xbuff = kmalloc(len + 4, GFP_KERNEL);
588
589 if (rbuff == NULL || xbuff == NULL) {
590 err = -ENOBUFS;
591 goto out_free;
592 }
593
594 spin_lock_bh(&sp->lock);
595
596 sp->tty = tty;
597
598 sp->rbuff = rbuff;
599 sp->xbuff = xbuff;
600
601 sp->mtu = AX25_MTU + 73;
602 sp->buffsize = len;
603 sp->rcount = 0;
604 sp->rx_count = 0;
605 sp->rx_count_cooked = 0;
606 sp->xleft = 0;
607
608 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
609
610 sp->duplex = 0;
611 sp->tx_delay = SIXP_TXDELAY;
612 sp->persistence = SIXP_PERSIST;
613 sp->slottime = SIXP_SLOTTIME;
614 sp->led_state = 0x60;
615 sp->status = 1;
616 sp->status1 = 1;
617 sp->status2 = 0;
618 sp->tx_enable = 0;
619
620 netif_start_queue(dev);
621
622 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
623
624 timer_setup(&sp->resync_t, resync_tnc, 0);
625
626 spin_unlock_bh(&sp->lock);
627
628 /* Done. We have linked the TTY line to a channel. */
629 tty->disc_data = sp;
630 tty->receive_room = 65536;
631
632 /* Now we're ready to register. */
633 err = register_netdev(dev);
634 if (err)
635 goto out_free;
636
637 tnc_init(sp);
638
639 return 0;
640
641 out_free:
642 kfree(xbuff);
643 kfree(rbuff);
644
645 free_netdev(dev);
646
647 out:
648 return err;
649 }
650
651
652 /*
653 * Close down a 6pack channel.
654 * This means flushing out any pending queues, and then restoring the
655 * TTY line discipline to what it was before it got hooked to 6pack
656 * (which usually is TTY again).
657 */
sixpack_close(struct tty_struct * tty)658 static void sixpack_close(struct tty_struct *tty)
659 {
660 struct sixpack *sp;
661
662 write_lock_bh(&disc_data_lock);
663 sp = tty->disc_data;
664 tty->disc_data = NULL;
665 write_unlock_bh(&disc_data_lock);
666 if (!sp)
667 return;
668
669 /*
670 * We have now ensured that nobody can start using ap from now on, but
671 * we have to wait for all existing users to finish.
672 */
673 if (!refcount_dec_and_test(&sp->refcnt))
674 down(&sp->dead_sem);
675
676 /* We must stop the queue to avoid potentially scribbling
677 * on the free buffers. The sp->dead_sem is not sufficient
678 * to protect us from sp->xbuff access.
679 */
680 netif_stop_queue(sp->dev);
681
682 del_timer_sync(&sp->tx_t);
683 del_timer_sync(&sp->resync_t);
684
685 /* Free all 6pack frame buffers. */
686 kfree(sp->rbuff);
687 kfree(sp->xbuff);
688
689 unregister_netdev(sp->dev);
690 }
691
692 /* Perform I/O control on an active 6pack channel. */
sixpack_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)693 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
694 unsigned int cmd, unsigned long arg)
695 {
696 struct sixpack *sp = sp_get(tty);
697 struct net_device *dev;
698 unsigned int tmp, err;
699
700 if (!sp)
701 return -ENXIO;
702 dev = sp->dev;
703
704 switch(cmd) {
705 case SIOCGIFNAME:
706 err = copy_to_user((void __user *) arg, dev->name,
707 strlen(dev->name) + 1) ? -EFAULT : 0;
708 break;
709
710 case SIOCGIFENCAP:
711 err = put_user(0, (int __user *) arg);
712 break;
713
714 case SIOCSIFENCAP:
715 if (get_user(tmp, (int __user *) arg)) {
716 err = -EFAULT;
717 break;
718 }
719
720 sp->mode = tmp;
721 dev->addr_len = AX25_ADDR_LEN;
722 dev->hard_header_len = AX25_KISS_HEADER_LEN +
723 AX25_MAX_HEADER_LEN + 3;
724 dev->type = ARPHRD_AX25;
725
726 err = 0;
727 break;
728
729 case SIOCSIFHWADDR: {
730 char addr[AX25_ADDR_LEN];
731
732 if (copy_from_user(&addr,
733 (void __user *) arg, AX25_ADDR_LEN)) {
734 err = -EFAULT;
735 break;
736 }
737
738 netif_tx_lock_bh(dev);
739 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
740 netif_tx_unlock_bh(dev);
741
742 err = 0;
743 break;
744 }
745
746 default:
747 err = tty_mode_ioctl(tty, file, cmd, arg);
748 }
749
750 sp_put(sp);
751
752 return err;
753 }
754
755 #ifdef CONFIG_COMPAT
sixpack_compat_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)756 static long sixpack_compat_ioctl(struct tty_struct * tty, struct file * file,
757 unsigned int cmd, unsigned long arg)
758 {
759 switch (cmd) {
760 case SIOCGIFNAME:
761 case SIOCGIFENCAP:
762 case SIOCSIFENCAP:
763 case SIOCSIFHWADDR:
764 return sixpack_ioctl(tty, file, cmd,
765 (unsigned long)compat_ptr(arg));
766 }
767
768 return -ENOIOCTLCMD;
769 }
770 #endif
771
772 static struct tty_ldisc_ops sp_ldisc = {
773 .owner = THIS_MODULE,
774 .magic = TTY_LDISC_MAGIC,
775 .name = "6pack",
776 .open = sixpack_open,
777 .close = sixpack_close,
778 .ioctl = sixpack_ioctl,
779 #ifdef CONFIG_COMPAT
780 .compat_ioctl = sixpack_compat_ioctl,
781 #endif
782 .receive_buf = sixpack_receive_buf,
783 .write_wakeup = sixpack_write_wakeup,
784 };
785
786 /* Initialize 6pack control device -- register 6pack line discipline */
787
788 static const char msg_banner[] __initconst = KERN_INFO \
789 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
790 static const char msg_regfail[] __initconst = KERN_ERR \
791 "6pack: can't register line discipline (err = %d)\n";
792
sixpack_init_driver(void)793 static int __init sixpack_init_driver(void)
794 {
795 int status;
796
797 printk(msg_banner);
798
799 /* Register the provided line protocol discipline */
800 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
801 printk(msg_regfail, status);
802
803 return status;
804 }
805
806 static const char msg_unregfail[] = KERN_ERR \
807 "6pack: can't unregister line discipline (err = %d)\n";
808
sixpack_exit_driver(void)809 static void __exit sixpack_exit_driver(void)
810 {
811 int ret;
812
813 if ((ret = tty_unregister_ldisc(N_6PACK)))
814 printk(msg_unregfail, ret);
815 }
816
817 /* encode an AX.25 packet into 6pack */
818
encode_sixpack(unsigned char * tx_buf,unsigned char * tx_buf_raw,int length,unsigned char tx_delay)819 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
820 int length, unsigned char tx_delay)
821 {
822 int count = 0;
823 unsigned char checksum = 0, buf[400];
824 int raw_count = 0;
825
826 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
827 tx_buf_raw[raw_count++] = SIXP_SEOF;
828
829 buf[0] = tx_delay;
830 for (count = 1; count < length; count++)
831 buf[count] = tx_buf[count];
832
833 for (count = 0; count < length; count++)
834 checksum += buf[count];
835 buf[length] = (unsigned char) 0xff - checksum;
836
837 for (count = 0; count <= length; count++) {
838 if ((count % 3) == 0) {
839 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
840 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
841 } else if ((count % 3) == 1) {
842 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
843 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
844 } else {
845 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
846 tx_buf_raw[raw_count++] = (buf[count] >> 2);
847 }
848 }
849 if ((length % 3) != 2)
850 raw_count++;
851 tx_buf_raw[raw_count++] = SIXP_SEOF;
852 return raw_count;
853 }
854
855 /* decode 4 sixpack-encoded bytes into 3 data bytes */
856
decode_data(struct sixpack * sp,unsigned char inbyte)857 static void decode_data(struct sixpack *sp, unsigned char inbyte)
858 {
859 unsigned char *buf;
860
861 if (sp->rx_count != 3) {
862 sp->raw_buf[sp->rx_count++] = inbyte;
863
864 return;
865 }
866
867 buf = sp->raw_buf;
868 sp->cooked_buf[sp->rx_count_cooked++] =
869 buf[0] | ((buf[1] << 2) & 0xc0);
870 sp->cooked_buf[sp->rx_count_cooked++] =
871 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
872 sp->cooked_buf[sp->rx_count_cooked++] =
873 (buf[2] & 0x03) | (inbyte << 2);
874 sp->rx_count = 0;
875 }
876
877 /* identify and execute a 6pack priority command byte */
878
decode_prio_command(struct sixpack * sp,unsigned char cmd)879 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
880 {
881 int actual;
882
883 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
884
885 /* RX and DCD flags can only be set in the same prio command,
886 if the DCD flag has been set without the RX flag in the previous
887 prio command. If DCD has not been set before, something in the
888 transmission has gone wrong. In this case, RX and DCD are
889 cleared in order to prevent the decode_data routine from
890 reading further data that might be corrupt. */
891
892 if (((sp->status & SIXP_DCD_MASK) == 0) &&
893 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
894 if (sp->status != 1)
895 printk(KERN_DEBUG "6pack: protocol violation\n");
896 else
897 sp->status = 0;
898 cmd &= ~SIXP_RX_DCD_MASK;
899 }
900 sp->status = cmd & SIXP_PRIO_DATA_MASK;
901 } else { /* output watchdog char if idle */
902 if ((sp->status2 != 0) && (sp->duplex == 1)) {
903 sp->led_state = 0x70;
904 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
905 sp->tx_enable = 1;
906 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
907 sp->xleft -= actual;
908 sp->xhead += actual;
909 sp->led_state = 0x60;
910 sp->status2 = 0;
911
912 }
913 }
914
915 /* needed to trigger the TNC watchdog */
916 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
917
918 /* if the state byte has been received, the TNC is present,
919 so the resync timer can be reset. */
920
921 if (sp->tnc_state == TNC_IN_SYNC) {
922 del_timer(&sp->resync_t);
923 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
924 add_timer(&sp->resync_t);
925 }
926
927 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
928 }
929
930 /* identify and execute a standard 6pack command byte */
931
decode_std_command(struct sixpack * sp,unsigned char cmd)932 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
933 {
934 unsigned char checksum = 0, rest = 0;
935 short i;
936
937 switch (cmd & SIXP_CMD_MASK) { /* normal command */
938 case SIXP_SEOF:
939 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
940 if ((sp->status & SIXP_RX_DCD_MASK) ==
941 SIXP_RX_DCD_MASK) {
942 sp->led_state = 0x68;
943 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
944 }
945 } else {
946 sp->led_state = 0x60;
947 /* fill trailing bytes with zeroes */
948 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
949 rest = sp->rx_count;
950 if (rest != 0)
951 for (i = rest; i <= 3; i++)
952 decode_data(sp, 0);
953 if (rest == 2)
954 sp->rx_count_cooked -= 2;
955 else if (rest == 3)
956 sp->rx_count_cooked -= 1;
957 for (i = 0; i < sp->rx_count_cooked; i++)
958 checksum += sp->cooked_buf[i];
959 if (checksum != SIXP_CHKSUM) {
960 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
961 } else {
962 sp->rcount = sp->rx_count_cooked-2;
963 sp_bump(sp, 0);
964 }
965 sp->rx_count_cooked = 0;
966 }
967 break;
968 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
969 break;
970 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
971 break;
972 case SIXP_RX_BUF_OVL:
973 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
974 }
975 }
976
977 /* decode a 6pack packet */
978
979 static void
sixpack_decode(struct sixpack * sp,const unsigned char * pre_rbuff,int count)980 sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
981 {
982 unsigned char inbyte;
983 int count1;
984
985 for (count1 = 0; count1 < count; count1++) {
986 inbyte = pre_rbuff[count1];
987 if (inbyte == SIXP_FOUND_TNC) {
988 tnc_set_sync_state(sp, TNC_IN_SYNC);
989 del_timer(&sp->resync_t);
990 }
991 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
992 decode_prio_command(sp, inbyte);
993 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
994 decode_std_command(sp, inbyte);
995 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
996 decode_data(sp, inbyte);
997 }
998 }
999
1000 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1001 MODULE_DESCRIPTION("6pack driver for AX.25");
1002 MODULE_LICENSE("GPL");
1003 MODULE_ALIAS_LDISC(N_6PACK);
1004
1005 module_init(sixpack_init_driver);
1006 module_exit(sixpack_exit_driver);
1007
