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@iehk.rwth-aachen.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/system.h>
17 #include <asm/uaccess.h>
18 #include <linux/bitops.h>
19 #include <linux/string.h>
20 #include <linux/mm.h>
21 #include <linux/interrupt.h>
22 #include <linux/in.h>
23 #include <linux/tty.h>
24 #include <linux/errno.h>
25 #include <linux/netdevice.h>
26 #include <linux/timer.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 <asm/atomic.h>
38
39 #define SIXPACK_VERSION "Revision: 0.3.0"
40
41 /* sixpack priority commands */
42 #define SIXP_SEOF 0x40 /* start and end of a 6pack frame */
43 #define SIXP_TX_URUN 0x48 /* transmit overrun */
44 #define SIXP_RX_ORUN 0x50 /* receive overrun */
45 #define SIXP_RX_BUF_OVL 0x58 /* receive buffer overflow */
46
47 #define SIXP_CHKSUM 0xFF /* valid checksum of a 6pack frame */
48
49 /* masks to get certain bits out of the status bytes sent by the TNC */
50
51 #define SIXP_CMD_MASK 0xC0
52 #define SIXP_CHN_MASK 0x07
53 #define SIXP_PRIO_CMD_MASK 0x80
54 #define SIXP_STD_CMD_MASK 0x40
55 #define SIXP_PRIO_DATA_MASK 0x38
56 #define SIXP_TX_MASK 0x20
57 #define SIXP_RX_MASK 0x10
58 #define SIXP_RX_DCD_MASK 0x18
59 #define SIXP_LEDS_ON 0x78
60 #define SIXP_LEDS_OFF 0x60
61 #define SIXP_CON 0x08
62 #define SIXP_STA 0x10
63
64 #define SIXP_FOUND_TNC 0xe9
65 #define SIXP_CON_ON 0x68
66 #define SIXP_DCD_MASK 0x08
67 #define SIXP_DAMA_OFF 0
68
69 /* default level 2 parameters */
70 #define SIXP_TXDELAY (HZ/4) /* in 1 s */
71 #define SIXP_PERSIST 50 /* in 256ths */
72 #define SIXP_SLOTTIME (HZ/10) /* in 1 s */
73 #define SIXP_INIT_RESYNC_TIMEOUT (3*HZ/2) /* in 1 s */
74 #define SIXP_RESYNC_TIMEOUT 5*HZ /* in 1 s */
75
76 /* 6pack configuration. */
77 #define SIXP_NRUNIT 31 /* MAX number of 6pack channels */
78 #define SIXP_MTU 256 /* Default MTU */
79
80 enum sixpack_flags {
81 SIXPF_ERROR, /* Parity, etc. error */
82 };
83
84 struct sixpack {
85 /* Various fields. */
86 struct tty_struct *tty; /* ptr to TTY structure */
87 struct net_device *dev; /* easy for intr handling */
88
89 /* These are pointers to the malloc()ed frame buffers. */
90 unsigned char *rbuff; /* receiver buffer */
91 int rcount; /* received chars counter */
92 unsigned char *xbuff; /* transmitter buffer */
93 unsigned char *xhead; /* next byte to XMIT */
94 int xleft; /* bytes left in XMIT queue */
95
96 unsigned char raw_buf[4];
97 unsigned char cooked_buf[400];
98
99 unsigned int rx_count;
100 unsigned int rx_count_cooked;
101
102 int mtu; /* Our mtu (to spot changes!) */
103 int buffsize; /* Max buffers sizes */
104
105 unsigned long flags; /* Flag values/ mode etc */
106 unsigned char mode; /* 6pack mode */
107
108 /* 6pack stuff */
109 unsigned char tx_delay;
110 unsigned char persistence;
111 unsigned char slottime;
112 unsigned char duplex;
113 unsigned char led_state;
114 unsigned char status;
115 unsigned char status1;
116 unsigned char status2;
117 unsigned char tx_enable;
118 unsigned char tnc_state;
119
120 struct timer_list tx_t;
121 struct timer_list resync_t;
122 atomic_t refcnt;
123 struct semaphore dead_sem;
124 spinlock_t lock;
125 };
126
127 #define AX25_6PACK_HEADER_LEN 0
128
129 static void sixpack_decode(struct sixpack *, unsigned char[], int);
130 static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
131
132 /*
133 * Perform the persistence/slottime algorithm for CSMA access. If the
134 * persistence check was successful, write the data to the serial driver.
135 * Note that in case of DAMA operation, the data is not sent here.
136 */
137
sp_xmit_on_air(unsigned long channel)138 static void sp_xmit_on_air(unsigned long channel)
139 {
140 struct sixpack *sp = (struct sixpack *) channel;
141 int actual, when = sp->slottime;
142 static unsigned char random;
143
144 random = random * 17 + 41;
145
146 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
147 sp->led_state = 0x70;
148 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
149 sp->tx_enable = 1;
150 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
151 sp->xleft -= actual;
152 sp->xhead += actual;
153 sp->led_state = 0x60;
154 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
155 sp->status2 = 0;
156 } else
157 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
158 }
159
160 /* ----> 6pack timer interrupt handler and friends. <---- */
161
162 /* Encapsulate one AX.25 frame and stuff into a TTY queue. */
sp_encaps(struct sixpack * sp,unsigned char * icp,int len)163 static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
164 {
165 unsigned char *msg, *p = icp;
166 int actual, count;
167
168 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
169 msg = "oversized transmit packet!";
170 goto out_drop;
171 }
172
173 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
174 msg = "oversized transmit packet!";
175 goto out_drop;
176 }
177
178 if (p[0] > 5) {
179 msg = "invalid KISS command";
180 goto out_drop;
181 }
182
183 if ((p[0] != 0) && (len > 2)) {
184 msg = "KISS control packet too long";
185 goto out_drop;
186 }
187
188 if ((p[0] == 0) && (len < 15)) {
189 msg = "bad AX.25 packet to transmit";
190 goto out_drop;
191 }
192
193 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
194 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
195
196 switch (p[0]) {
197 case 1: sp->tx_delay = p[1];
198 return;
199 case 2: sp->persistence = p[1];
200 return;
201 case 3: sp->slottime = p[1];
202 return;
203 case 4: /* ignored */
204 return;
205 case 5: sp->duplex = p[1];
206 return;
207 }
208
209 if (p[0] != 0)
210 return;
211
212 /*
213 * In case of fullduplex or DAMA operation, we don't take care about the
214 * state of the DCD or of any timers, as the determination of the
215 * correct time to send is the job of the AX.25 layer. We send
216 * immediately after data has arrived.
217 */
218 if (sp->duplex == 1) {
219 sp->led_state = 0x70;
220 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
221 sp->tx_enable = 1;
222 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
223 sp->xleft = count - actual;
224 sp->xhead = sp->xbuff + actual;
225 sp->led_state = 0x60;
226 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
227 } else {
228 sp->xleft = count;
229 sp->xhead = sp->xbuff;
230 sp->status2 = count;
231 sp_xmit_on_air((unsigned long)sp);
232 }
233
234 return;
235
236 out_drop:
237 sp->dev->stats.tx_dropped++;
238 netif_start_queue(sp->dev);
239 if (net_ratelimit())
240 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
241 }
242
243 /* Encapsulate an IP datagram and kick it into a TTY queue. */
244
sp_xmit(struct sk_buff * skb,struct net_device * dev)245 static int sp_xmit(struct sk_buff *skb, struct net_device *dev)
246 {
247 struct sixpack *sp = netdev_priv(dev);
248
249 spin_lock_bh(&sp->lock);
250 /* We were not busy, so we are now... :-) */
251 netif_stop_queue(dev);
252 dev->stats.tx_bytes += skb->len;
253 sp_encaps(sp, skb->data, skb->len);
254 spin_unlock_bh(&sp->lock);
255
256 dev_kfree_skb(skb);
257
258 return 0;
259 }
260
sp_open_dev(struct net_device * dev)261 static int sp_open_dev(struct net_device *dev)
262 {
263 struct sixpack *sp = netdev_priv(dev);
264
265 if (sp->tty == NULL)
266 return -ENODEV;
267 return 0;
268 }
269
270 /* Close the low-level part of the 6pack channel. */
sp_close(struct net_device * dev)271 static int sp_close(struct net_device *dev)
272 {
273 struct sixpack *sp = netdev_priv(dev);
274
275 spin_lock_bh(&sp->lock);
276 if (sp->tty) {
277 /* TTY discipline is running. */
278 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
279 }
280 netif_stop_queue(dev);
281 spin_unlock_bh(&sp->lock);
282
283 return 0;
284 }
285
286 /* 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)287 static int sp_header(struct sk_buff *skb, struct net_device *dev,
288 unsigned short type, const void *daddr,
289 const void *saddr, unsigned len)
290 {
291 #ifdef CONFIG_INET
292 if (type != ETH_P_AX25)
293 return ax25_hard_header(skb, dev, type, daddr, saddr, len);
294 #endif
295 return 0;
296 }
297
sp_set_mac_address(struct net_device * dev,void * addr)298 static int sp_set_mac_address(struct net_device *dev, void *addr)
299 {
300 struct sockaddr_ax25 *sa = addr;
301
302 netif_tx_lock_bh(dev);
303 netif_addr_lock(dev);
304 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
305 netif_addr_unlock(dev);
306 netif_tx_unlock_bh(dev);
307
308 return 0;
309 }
310
sp_rebuild_header(struct sk_buff * skb)311 static int sp_rebuild_header(struct sk_buff *skb)
312 {
313 #ifdef CONFIG_INET
314 return ax25_rebuild_header(skb);
315 #else
316 return 0;
317 #endif
318 }
319
320 static const struct header_ops sp_header_ops = {
321 .create = sp_header,
322 .rebuild = sp_rebuild_header,
323 };
324
sp_setup(struct net_device * dev)325 static void sp_setup(struct net_device *dev)
326 {
327 /* Finish setting up the DEVICE info. */
328 dev->mtu = SIXP_MTU;
329 dev->hard_start_xmit = sp_xmit;
330 dev->open = sp_open_dev;
331 dev->destructor = free_netdev;
332 dev->stop = sp_close;
333
334 dev->set_mac_address = sp_set_mac_address;
335 dev->hard_header_len = AX25_MAX_HEADER_LEN;
336 dev->header_ops = &sp_header_ops;
337
338 dev->addr_len = AX25_ADDR_LEN;
339 dev->type = ARPHRD_AX25;
340 dev->tx_queue_len = 10;
341 dev->tx_timeout = NULL;
342
343 /* Only activated in AX.25 mode */
344 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
345 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
346
347 dev->flags = 0;
348 }
349
350 /* Send one completely decapsulated IP datagram to the IP layer. */
351
352 /*
353 * This is the routine that sends the received data to the kernel AX.25.
354 * 'cmd' is the KISS command. For AX.25 data, it is zero.
355 */
356
sp_bump(struct sixpack * sp,char cmd)357 static void sp_bump(struct sixpack *sp, char cmd)
358 {
359 struct sk_buff *skb;
360 int count;
361 unsigned char *ptr;
362
363 count = sp->rcount + 1;
364
365 sp->dev->stats.rx_bytes += count;
366
367 if ((skb = dev_alloc_skb(count)) == NULL)
368 goto out_mem;
369
370 ptr = skb_put(skb, count);
371 *ptr++ = cmd; /* KISS command */
372
373 memcpy(ptr, sp->cooked_buf + 1, count);
374 skb->protocol = ax25_type_trans(skb, sp->dev);
375 netif_rx(skb);
376 sp->dev->stats.rx_packets++;
377
378 return;
379
380 out_mem:
381 sp->dev->stats.rx_dropped++;
382 }
383
384
385 /* ----------------------------------------------------------------------- */
386
387 /*
388 * We have a potential race on dereferencing tty->disc_data, because the tty
389 * layer provides no locking at all - thus one cpu could be running
390 * sixpack_receive_buf while another calls sixpack_close, which zeroes
391 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
392 * best way to fix this is to use a rwlock in the tty struct, but for now we
393 * use a single global rwlock for all ttys in ppp line discipline.
394 */
395 static DEFINE_RWLOCK(disc_data_lock);
396
sp_get(struct tty_struct * tty)397 static struct sixpack *sp_get(struct tty_struct *tty)
398 {
399 struct sixpack *sp;
400
401 read_lock(&disc_data_lock);
402 sp = tty->disc_data;
403 if (sp)
404 atomic_inc(&sp->refcnt);
405 read_unlock(&disc_data_lock);
406
407 return sp;
408 }
409
sp_put(struct sixpack * sp)410 static void sp_put(struct sixpack *sp)
411 {
412 if (atomic_dec_and_test(&sp->refcnt))
413 up(&sp->dead_sem);
414 }
415
416 /*
417 * Called by the TTY driver when there's room for more data. If we have
418 * more packets to send, we send them here.
419 */
sixpack_write_wakeup(struct tty_struct * tty)420 static void sixpack_write_wakeup(struct tty_struct *tty)
421 {
422 struct sixpack *sp = sp_get(tty);
423 int actual;
424
425 if (!sp)
426 return;
427 if (sp->xleft <= 0) {
428 /* Now serial buffer is almost free & we can start
429 * transmission of another packet */
430 sp->dev->stats.tx_packets++;
431 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
432 sp->tx_enable = 0;
433 netif_wake_queue(sp->dev);
434 goto out;
435 }
436
437 if (sp->tx_enable) {
438 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
439 sp->xleft -= actual;
440 sp->xhead += actual;
441 }
442
443 out:
444 sp_put(sp);
445 }
446
447 /* ----------------------------------------------------------------------- */
448
449 /*
450 * Handle the 'receiver data ready' interrupt.
451 * This function is called by the 'tty_io' module in the kernel when
452 * a block of 6pack data has been received, which can now be decapsulated
453 * and sent on to some IP layer for further processing.
454 */
sixpack_receive_buf(struct tty_struct * tty,const unsigned char * cp,char * fp,int count)455 static void sixpack_receive_buf(struct tty_struct *tty,
456 const unsigned char *cp, char *fp, int count)
457 {
458 struct sixpack *sp;
459 unsigned char buf[512];
460 int count1;
461
462 if (!count)
463 return;
464
465 sp = sp_get(tty);
466 if (!sp)
467 return;
468
469 memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
470
471 /* Read the characters out of the buffer */
472
473 count1 = count;
474 while (count) {
475 count--;
476 if (fp && *fp++) {
477 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
478 sp->dev->stats.rx_errors++;
479 continue;
480 }
481 }
482 sixpack_decode(sp, buf, count1);
483
484 sp_put(sp);
485 tty_unthrottle(tty);
486 }
487
488 /*
489 * Try to resync the TNC. Called by the resync timer defined in
490 * decode_prio_command
491 */
492
493 #define TNC_UNINITIALIZED 0
494 #define TNC_UNSYNC_STARTUP 1
495 #define TNC_UNSYNCED 2
496 #define TNC_IN_SYNC 3
497
__tnc_set_sync_state(struct sixpack * sp,int new_tnc_state)498 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
499 {
500 char *msg;
501
502 switch (new_tnc_state) {
503 default: /* gcc oh piece-o-crap ... */
504 case TNC_UNSYNC_STARTUP:
505 msg = "Synchronizing with TNC";
506 break;
507 case TNC_UNSYNCED:
508 msg = "Lost synchronization with TNC\n";
509 break;
510 case TNC_IN_SYNC:
511 msg = "Found TNC";
512 break;
513 }
514
515 sp->tnc_state = new_tnc_state;
516 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
517 }
518
tnc_set_sync_state(struct sixpack * sp,int new_tnc_state)519 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
520 {
521 int old_tnc_state = sp->tnc_state;
522
523 if (old_tnc_state != new_tnc_state)
524 __tnc_set_sync_state(sp, new_tnc_state);
525 }
526
resync_tnc(unsigned long channel)527 static void resync_tnc(unsigned long channel)
528 {
529 struct sixpack *sp = (struct sixpack *) channel;
530 static char resync_cmd = 0xe8;
531
532 /* clear any data that might have been received */
533
534 sp->rx_count = 0;
535 sp->rx_count_cooked = 0;
536
537 /* reset state machine */
538
539 sp->status = 1;
540 sp->status1 = 1;
541 sp->status2 = 0;
542
543 /* resync the TNC */
544
545 sp->led_state = 0x60;
546 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
547 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
548
549
550 /* Start resync timer again -- the TNC might be still absent */
551
552 del_timer(&sp->resync_t);
553 sp->resync_t.data = (unsigned long) sp;
554 sp->resync_t.function = resync_tnc;
555 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
556 add_timer(&sp->resync_t);
557 }
558
tnc_init(struct sixpack * sp)559 static inline int tnc_init(struct sixpack *sp)
560 {
561 unsigned char inbyte = 0xe8;
562
563 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
564
565 sp->tty->ops->write(sp->tty, &inbyte, 1);
566
567 del_timer(&sp->resync_t);
568 sp->resync_t.data = (unsigned long) sp;
569 sp->resync_t.function = resync_tnc;
570 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
571 add_timer(&sp->resync_t);
572
573 return 0;
574 }
575
576 /*
577 * Open the high-level part of the 6pack channel.
578 * This function is called by the TTY module when the
579 * 6pack line discipline is called for. Because we are
580 * sure the tty line exists, we only have to link it to
581 * a free 6pcack channel...
582 */
sixpack_open(struct tty_struct * tty)583 static int sixpack_open(struct tty_struct *tty)
584 {
585 char *rbuff = NULL, *xbuff = NULL;
586 struct net_device *dev;
587 struct sixpack *sp;
588 unsigned long len;
589 int err = 0;
590
591 if (!capable(CAP_NET_ADMIN))
592 return -EPERM;
593 if (tty->ops->write == NULL)
594 return -EOPNOTSUPP;
595
596 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
597 if (!dev) {
598 err = -ENOMEM;
599 goto out;
600 }
601
602 sp = netdev_priv(dev);
603 sp->dev = dev;
604
605 spin_lock_init(&sp->lock);
606 atomic_set(&sp->refcnt, 1);
607 init_MUTEX_LOCKED(&sp->dead_sem);
608
609 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
610
611 len = dev->mtu * 2;
612
613 rbuff = kmalloc(len + 4, GFP_KERNEL);
614 xbuff = kmalloc(len + 4, GFP_KERNEL);
615
616 if (rbuff == NULL || xbuff == NULL) {
617 err = -ENOBUFS;
618 goto out_free;
619 }
620
621 spin_lock_bh(&sp->lock);
622
623 sp->tty = tty;
624
625 sp->rbuff = rbuff;
626 sp->xbuff = xbuff;
627
628 sp->mtu = AX25_MTU + 73;
629 sp->buffsize = len;
630 sp->rcount = 0;
631 sp->rx_count = 0;
632 sp->rx_count_cooked = 0;
633 sp->xleft = 0;
634
635 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
636
637 sp->duplex = 0;
638 sp->tx_delay = SIXP_TXDELAY;
639 sp->persistence = SIXP_PERSIST;
640 sp->slottime = SIXP_SLOTTIME;
641 sp->led_state = 0x60;
642 sp->status = 1;
643 sp->status1 = 1;
644 sp->status2 = 0;
645 sp->tx_enable = 0;
646
647 netif_start_queue(dev);
648
649 init_timer(&sp->tx_t);
650 sp->tx_t.function = sp_xmit_on_air;
651 sp->tx_t.data = (unsigned long) sp;
652
653 init_timer(&sp->resync_t);
654
655 spin_unlock_bh(&sp->lock);
656
657 /* Done. We have linked the TTY line to a channel. */
658 tty->disc_data = sp;
659 tty->receive_room = 65536;
660
661 /* Now we're ready to register. */
662 if (register_netdev(dev))
663 goto out_free;
664
665 tnc_init(sp);
666
667 return 0;
668
669 out_free:
670 kfree(xbuff);
671 kfree(rbuff);
672
673 if (dev)
674 free_netdev(dev);
675
676 out:
677 return err;
678 }
679
680
681 /*
682 * Close down a 6pack channel.
683 * This means flushing out any pending queues, and then restoring the
684 * TTY line discipline to what it was before it got hooked to 6pack
685 * (which usually is TTY again).
686 */
sixpack_close(struct tty_struct * tty)687 static void sixpack_close(struct tty_struct *tty)
688 {
689 struct sixpack *sp;
690
691 write_lock(&disc_data_lock);
692 sp = tty->disc_data;
693 tty->disc_data = NULL;
694 write_unlock(&disc_data_lock);
695 if (!sp)
696 return;
697
698 /*
699 * We have now ensured that nobody can start using ap from now on, but
700 * we have to wait for all existing users to finish.
701 */
702 if (!atomic_dec_and_test(&sp->refcnt))
703 down(&sp->dead_sem);
704
705 unregister_netdev(sp->dev);
706
707 del_timer(&sp->tx_t);
708 del_timer(&sp->resync_t);
709
710 /* Free all 6pack frame buffers. */
711 kfree(sp->rbuff);
712 kfree(sp->xbuff);
713 }
714
715 /* Perform I/O control on an active 6pack channel. */
sixpack_ioctl(struct tty_struct * tty,struct file * file,unsigned int cmd,unsigned long arg)716 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
717 unsigned int cmd, unsigned long arg)
718 {
719 struct sixpack *sp = sp_get(tty);
720 struct net_device *dev;
721 unsigned int tmp, err;
722
723 if (!sp)
724 return -ENXIO;
725 dev = sp->dev;
726
727 switch(cmd) {
728 case SIOCGIFNAME:
729 err = copy_to_user((void __user *) arg, dev->name,
730 strlen(dev->name) + 1) ? -EFAULT : 0;
731 break;
732
733 case SIOCGIFENCAP:
734 err = put_user(0, (int __user *) arg);
735 break;
736
737 case SIOCSIFENCAP:
738 if (get_user(tmp, (int __user *) arg)) {
739 err = -EFAULT;
740 break;
741 }
742
743 sp->mode = tmp;
744 dev->addr_len = AX25_ADDR_LEN;
745 dev->hard_header_len = AX25_KISS_HEADER_LEN +
746 AX25_MAX_HEADER_LEN + 3;
747 dev->type = ARPHRD_AX25;
748
749 err = 0;
750 break;
751
752 case SIOCSIFHWADDR: {
753 char addr[AX25_ADDR_LEN];
754
755 if (copy_from_user(&addr,
756 (void __user *) arg, AX25_ADDR_LEN)) {
757 err = -EFAULT;
758 break;
759 }
760
761 netif_tx_lock_bh(dev);
762 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
763 netif_tx_unlock_bh(dev);
764
765 err = 0;
766 break;
767 }
768
769 default:
770 err = tty_mode_ioctl(tty, file, cmd, arg);
771 }
772
773 sp_put(sp);
774
775 return err;
776 }
777
778 static 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 .receive_buf = sixpack_receive_buf,
786 .write_wakeup = sixpack_write_wakeup,
787 };
788
789 /* Initialize 6pack control device -- register 6pack line discipline */
790
791 static char msg_banner[] __initdata = KERN_INFO \
792 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
793 static char msg_regfail[] __initdata = KERN_ERR \
794 "6pack: can't register line discipline (err = %d)\n";
795
sixpack_init_driver(void)796 static int __init sixpack_init_driver(void)
797 {
798 int status;
799
800 printk(msg_banner);
801
802 /* Register the provided line protocol discipline */
803 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
804 printk(msg_regfail, status);
805
806 return status;
807 }
808
809 static const char msg_unregfail[] __exitdata = KERN_ERR \
810 "6pack: can't unregister line discipline (err = %d)\n";
811
sixpack_exit_driver(void)812 static void __exit sixpack_exit_driver(void)
813 {
814 int ret;
815
816 if ((ret = tty_unregister_ldisc(N_6PACK)))
817 printk(msg_unregfail, ret);
818 }
819
820 /* encode an AX.25 packet into 6pack */
821
encode_sixpack(unsigned char * tx_buf,unsigned char * tx_buf_raw,int length,unsigned char tx_delay)822 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
823 int length, unsigned char tx_delay)
824 {
825 int count = 0;
826 unsigned char checksum = 0, buf[400];
827 int raw_count = 0;
828
829 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
830 tx_buf_raw[raw_count++] = SIXP_SEOF;
831
832 buf[0] = tx_delay;
833 for (count = 1; count < length; count++)
834 buf[count] = tx_buf[count];
835
836 for (count = 0; count < length; count++)
837 checksum += buf[count];
838 buf[length] = (unsigned char) 0xff - checksum;
839
840 for (count = 0; count <= length; count++) {
841 if ((count % 3) == 0) {
842 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
843 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
844 } else if ((count % 3) == 1) {
845 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
846 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
847 } else {
848 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
849 tx_buf_raw[raw_count++] = (buf[count] >> 2);
850 }
851 }
852 if ((length % 3) != 2)
853 raw_count++;
854 tx_buf_raw[raw_count++] = SIXP_SEOF;
855 return raw_count;
856 }
857
858 /* decode 4 sixpack-encoded bytes into 3 data bytes */
859
decode_data(struct sixpack * sp,unsigned char inbyte)860 static void decode_data(struct sixpack *sp, unsigned char inbyte)
861 {
862 unsigned char *buf;
863
864 if (sp->rx_count != 3) {
865 sp->raw_buf[sp->rx_count++] = inbyte;
866
867 return;
868 }
869
870 buf = sp->raw_buf;
871 sp->cooked_buf[sp->rx_count_cooked++] =
872 buf[0] | ((buf[1] << 2) & 0xc0);
873 sp->cooked_buf[sp->rx_count_cooked++] =
874 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
875 sp->cooked_buf[sp->rx_count_cooked++] =
876 (buf[2] & 0x03) | (inbyte << 2);
877 sp->rx_count = 0;
878 }
879
880 /* identify and execute a 6pack priority command byte */
881
decode_prio_command(struct sixpack * sp,unsigned char cmd)882 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
883 {
884 unsigned char channel;
885 int actual;
886
887 channel = cmd & SIXP_CHN_MASK;
888 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
889
890 /* RX and DCD flags can only be set in the same prio command,
891 if the DCD flag has been set without the RX flag in the previous
892 prio command. If DCD has not been set before, something in the
893 transmission has gone wrong. In this case, RX and DCD are
894 cleared in order to prevent the decode_data routine from
895 reading further data that might be corrupt. */
896
897 if (((sp->status & SIXP_DCD_MASK) == 0) &&
898 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
899 if (sp->status != 1)
900 printk(KERN_DEBUG "6pack: protocol violation\n");
901 else
902 sp->status = 0;
903 cmd &= ~SIXP_RX_DCD_MASK;
904 }
905 sp->status = cmd & SIXP_PRIO_DATA_MASK;
906 } else { /* output watchdog char if idle */
907 if ((sp->status2 != 0) && (sp->duplex == 1)) {
908 sp->led_state = 0x70;
909 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
910 sp->tx_enable = 1;
911 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
912 sp->xleft -= actual;
913 sp->xhead += actual;
914 sp->led_state = 0x60;
915 sp->status2 = 0;
916
917 }
918 }
919
920 /* needed to trigger the TNC watchdog */
921 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
922
923 /* if the state byte has been received, the TNC is present,
924 so the resync timer can be reset. */
925
926 if (sp->tnc_state == TNC_IN_SYNC) {
927 del_timer(&sp->resync_t);
928 sp->resync_t.data = (unsigned long) sp;
929 sp->resync_t.function = resync_tnc;
930 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
931 add_timer(&sp->resync_t);
932 }
933
934 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
935 }
936
937 /* identify and execute a standard 6pack command byte */
938
decode_std_command(struct sixpack * sp,unsigned char cmd)939 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
940 {
941 unsigned char checksum = 0, rest = 0, channel;
942 short i;
943
944 channel = cmd & SIXP_CHN_MASK;
945 switch (cmd & SIXP_CMD_MASK) { /* normal command */
946 case SIXP_SEOF:
947 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
948 if ((sp->status & SIXP_RX_DCD_MASK) ==
949 SIXP_RX_DCD_MASK) {
950 sp->led_state = 0x68;
951 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
952 }
953 } else {
954 sp->led_state = 0x60;
955 /* fill trailing bytes with zeroes */
956 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
957 rest = sp->rx_count;
958 if (rest != 0)
959 for (i = rest; i <= 3; i++)
960 decode_data(sp, 0);
961 if (rest == 2)
962 sp->rx_count_cooked -= 2;
963 else if (rest == 3)
964 sp->rx_count_cooked -= 1;
965 for (i = 0; i < sp->rx_count_cooked; i++)
966 checksum += sp->cooked_buf[i];
967 if (checksum != SIXP_CHKSUM) {
968 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
969 } else {
970 sp->rcount = sp->rx_count_cooked-2;
971 sp_bump(sp, 0);
972 }
973 sp->rx_count_cooked = 0;
974 }
975 break;
976 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
977 break;
978 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
979 break;
980 case SIXP_RX_BUF_OVL:
981 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
982 }
983 }
984
985 /* decode a 6pack packet */
986
987 static void
sixpack_decode(struct sixpack * sp,unsigned char * pre_rbuff,int count)988 sixpack_decode(struct sixpack *sp, unsigned char *pre_rbuff, int count)
989 {
990 unsigned char inbyte;
991 int count1;
992
993 for (count1 = 0; count1 < count; count1++) {
994 inbyte = pre_rbuff[count1];
995 if (inbyte == SIXP_FOUND_TNC) {
996 tnc_set_sync_state(sp, TNC_IN_SYNC);
997 del_timer(&sp->resync_t);
998 }
999 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
1000 decode_prio_command(sp, inbyte);
1001 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
1002 decode_std_command(sp, inbyte);
1003 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
1004 decode_data(sp, inbyte);
1005 }
1006 }
1007
1008 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
1009 MODULE_DESCRIPTION("6pack driver for AX.25");
1010 MODULE_LICENSE("GPL");
1011 MODULE_ALIAS_LDISC(N_6PACK);
1012
1013 module_init(sixpack_init_driver);
1014 module_exit(sixpack_exit_driver);
1015