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perf tools: Don't clone maps from parent when synthesizing forks
[linux/fpc-iii.git] / drivers / net / hamradio / 6pack.c
blob17e6dcd2eb4248c6378439194a283ad1f93f70c6
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/refcount.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 refcount_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 *, const 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
138 static void sp_xmit_on_air(struct timer_list *t)
139 {
140 struct sixpack *sp = from_timer(sp, t, tx_t);
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. */
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(&sp->tx_t);
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
245 static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
246 {
247 struct sixpack *sp = netdev_priv(dev);
248
249 if (skb->protocol == htons(ETH_P_IP))
250 return ax25_ip_xmit(skb);
251
252 spin_lock_bh(&sp->lock);
253 /* We were not busy, so we are now... :-) */
254 netif_stop_queue(dev);
255 dev->stats.tx_bytes += skb->len;
256 sp_encaps(sp, skb->data, skb->len);
257 spin_unlock_bh(&sp->lock);
258
259 dev_kfree_skb(skb);
260
261 return NETDEV_TX_OK;
262 }
263
264 static int sp_open_dev(struct net_device *dev)
265 {
266 struct sixpack *sp = netdev_priv(dev);
267
268 if (sp->tty == NULL)
269 return -ENODEV;
270 return 0;
271 }
272
273 /* Close the low-level part of the 6pack channel. */
274 static int sp_close(struct net_device *dev)
275 {
276 struct sixpack *sp = netdev_priv(dev);
277
278 spin_lock_bh(&sp->lock);
279 if (sp->tty) {
280 /* TTY discipline is running. */
281 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
282 }
283 netif_stop_queue(dev);
284 spin_unlock_bh(&sp->lock);
285
286 return 0;
287 }
288
289 static int sp_set_mac_address(struct net_device *dev, void *addr)
290 {
291 struct sockaddr_ax25 *sa = addr;
292
293 netif_tx_lock_bh(dev);
294 netif_addr_lock(dev);
295 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
296 netif_addr_unlock(dev);
297 netif_tx_unlock_bh(dev);
298
299 return 0;
300 }
301
302 static const struct net_device_ops sp_netdev_ops = {
303 .ndo_open = sp_open_dev,
304 .ndo_stop = sp_close,
305 .ndo_start_xmit = sp_xmit,
306 .ndo_set_mac_address = sp_set_mac_address,
307 };
308
309 static void sp_setup(struct net_device *dev)
310 {
311 /* Finish setting up the DEVICE info. */
312 dev->netdev_ops = &sp_netdev_ops;
313 dev->needs_free_netdev = true;
314 dev->mtu = SIXP_MTU;
315 dev->hard_header_len = AX25_MAX_HEADER_LEN;
316 dev->header_ops = &ax25_header_ops;
317
318 dev->addr_len = AX25_ADDR_LEN;
319 dev->type = ARPHRD_AX25;
320 dev->tx_queue_len = 10;
321
322 /* Only activated in AX.25 mode */
323 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
324 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
325
326 dev->flags = 0;
327 }
328
329 /* Send one completely decapsulated IP datagram to the IP layer. */
330
331 /*
332 * This is the routine that sends the received data to the kernel AX.25.
333 * 'cmd' is the KISS command. For AX.25 data, it is zero.
334 */
335
336 static void sp_bump(struct sixpack *sp, char cmd)
337 {
338 struct sk_buff *skb;
339 int count;
340 unsigned char *ptr;
341
342 count = sp->rcount + 1;
343
344 sp->dev->stats.rx_bytes += count;
345
346 if ((skb = dev_alloc_skb(count)) == NULL)
347 goto out_mem;
348
349 ptr = skb_put(skb, count);
350 *ptr++ = cmd; /* KISS command */
351
352 memcpy(ptr, sp->cooked_buf + 1, count);
353 skb->protocol = ax25_type_trans(skb, sp->dev);
354 netif_rx(skb);
355 sp->dev->stats.rx_packets++;
356
357 return;
358
359 out_mem:
360 sp->dev->stats.rx_dropped++;
361 }
362
363
364 /* ----------------------------------------------------------------------- */
365
366 /*
367 * We have a potential race on dereferencing tty->disc_data, because the tty
368 * layer provides no locking at all - thus one cpu could be running
369 * sixpack_receive_buf while another calls sixpack_close, which zeroes
370 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
371 * best way to fix this is to use a rwlock in the tty struct, but for now we
372 * use a single global rwlock for all ttys in ppp line discipline.
373 */
374 static DEFINE_RWLOCK(disc_data_lock);
375
376 static struct sixpack *sp_get(struct tty_struct *tty)
377 {
378 struct sixpack *sp;
379
380 read_lock(&disc_data_lock);
381 sp = tty->disc_data;
382 if (sp)
383 refcount_inc(&sp->refcnt);
384 read_unlock(&disc_data_lock);
385
386 return sp;
387 }
388
389 static void sp_put(struct sixpack *sp)
390 {
391 if (refcount_dec_and_test(&sp->refcnt))
392 up(&sp->dead_sem);
393 }
394
395 /*
396 * Called by the TTY driver when there's room for more data. If we have
397 * more packets to send, we send them here.
398 */
399 static void sixpack_write_wakeup(struct tty_struct *tty)
400 {
401 struct sixpack *sp = sp_get(tty);
402 int actual;
403
404 if (!sp)
405 return;
406 if (sp->xleft <= 0) {
407 /* Now serial buffer is almost free & we can start
408 * transmission of another packet */
409 sp->dev->stats.tx_packets++;
410 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
411 sp->tx_enable = 0;
412 netif_wake_queue(sp->dev);
413 goto out;
414 }
415
416 if (sp->tx_enable) {
417 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
418 sp->xleft -= actual;
419 sp->xhead += actual;
420 }
421
422 out:
423 sp_put(sp);
424 }
425
426 /* ----------------------------------------------------------------------- */
427
428 /*
429 * Handle the 'receiver data ready' interrupt.
430 * This function is called by the tty module in the kernel when
431 * a block of 6pack data has been received, which can now be decapsulated
432 * and sent on to some IP layer for further processing.
433 */
434 static void sixpack_receive_buf(struct tty_struct *tty,
435 const unsigned char *cp, char *fp, int count)
436 {
437 struct sixpack *sp;
438 int count1;
439
440 if (!count)
441 return;
442
443 sp = sp_get(tty);
444 if (!sp)
445 return;
446
447 /* Read the characters out of the buffer */
448 count1 = count;
449 while (count) {
450 count--;
451 if (fp && *fp++) {
452 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
453 sp->dev->stats.rx_errors++;
454 continue;
455 }
456 }
457 sixpack_decode(sp, cp, count1);
458
459 sp_put(sp);
460 tty_unthrottle(tty);
461 }
462
463 /*
464 * Try to resync the TNC. Called by the resync timer defined in
465 * decode_prio_command
466 */
467
468 #define TNC_UNINITIALIZED 0
469 #define TNC_UNSYNC_STARTUP 1
470 #define TNC_UNSYNCED 2
471 #define TNC_IN_SYNC 3
472
473 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
474 {
475 char *msg;
476
477 switch (new_tnc_state) {
478 default: /* gcc oh piece-o-crap ... */
479 case TNC_UNSYNC_STARTUP:
480 msg = "Synchronizing with TNC";
481 break;
482 case TNC_UNSYNCED:
483 msg = "Lost synchronization with TNC\n";
484 break;
485 case TNC_IN_SYNC:
486 msg = "Found TNC";
487 break;
488 }
489
490 sp->tnc_state = new_tnc_state;
491 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
492 }
493
494 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
495 {
496 int old_tnc_state = sp->tnc_state;
497
498 if (old_tnc_state != new_tnc_state)
499 __tnc_set_sync_state(sp, new_tnc_state);
500 }
501
502 static void resync_tnc(struct timer_list *t)
503 {
504 struct sixpack *sp = from_timer(sp, t, resync_t);
505 static char resync_cmd = 0xe8;
506
507 /* clear any data that might have been received */
508
509 sp->rx_count = 0;
510 sp->rx_count_cooked = 0;
511
512 /* reset state machine */
513
514 sp->status = 1;
515 sp->status1 = 1;
516 sp->status2 = 0;
517
518 /* resync the TNC */
519
520 sp->led_state = 0x60;
521 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
522 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
523
524
525 /* Start resync timer again -- the TNC might be still absent */
526
527 del_timer(&sp->resync_t);
528 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
529 add_timer(&sp->resync_t);
530 }
531
532 static inline int tnc_init(struct sixpack *sp)
533 {
534 unsigned char inbyte = 0xe8;
535
536 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
537
538 sp->tty->ops->write(sp->tty, &inbyte, 1);
539
540 del_timer(&sp->resync_t);
541 sp->resync_t.expires = jiffies + SIXP_RESYNC_TIMEOUT;
542 add_timer(&sp->resync_t);
543
544 return 0;
545 }
546
547 /*
548 * Open the high-level part of the 6pack channel.
549 * This function is called by the TTY module when the
550 * 6pack line discipline is called for. Because we are
551 * sure the tty line exists, we only have to link it to
552 * a free 6pcack channel...
553 */
554 static int sixpack_open(struct tty_struct *tty)
555 {
556 char *rbuff = NULL, *xbuff = NULL;
557 struct net_device *dev;
558 struct sixpack *sp;
559 unsigned long len;
560 int err = 0;
561
562 if (!capable(CAP_NET_ADMIN))
563 return -EPERM;
564 if (tty->ops->write == NULL)
565 return -EOPNOTSUPP;
566
567 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
568 sp_setup);
569 if (!dev) {
570 err = -ENOMEM;
571 goto out;
572 }
573
574 sp = netdev_priv(dev);
575 sp->dev = dev;
576
577 spin_lock_init(&sp->lock);
578 refcount_set(&sp->refcnt, 1);
579 sema_init(&sp->dead_sem, 0);
580
581 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
582
583 len = dev->mtu * 2;
584
585 rbuff = kmalloc(len + 4, GFP_KERNEL);
586 xbuff = kmalloc(len + 4, GFP_KERNEL);
587
588 if (rbuff == NULL || xbuff == NULL) {
589 err = -ENOBUFS;
590 goto out_free;
591 }
592
593 spin_lock_bh(&sp->lock);
594
595 sp->tty = tty;
596
597 sp->rbuff = rbuff;
598 sp->xbuff = xbuff;
599
600 sp->mtu = AX25_MTU + 73;
601 sp->buffsize = len;
602 sp->rcount = 0;
603 sp->rx_count = 0;
604 sp->rx_count_cooked = 0;
605 sp->xleft = 0;
606
607 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
608
609 sp->duplex = 0;
610 sp->tx_delay = SIXP_TXDELAY;
611 sp->persistence = SIXP_PERSIST;
612 sp->slottime = SIXP_SLOTTIME;
613 sp->led_state = 0x60;
614 sp->status = 1;
615 sp->status1 = 1;
616 sp->status2 = 0;
617 sp->tx_enable = 0;
618
619 netif_start_queue(dev);
620
621 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
622
623 timer_setup(&sp->resync_t, resync_tnc, 0);
624
625 spin_unlock_bh(&sp->lock);
626
627 /* Done. We have linked the TTY line to a channel. */
628 tty->disc_data = sp;
629 tty->receive_room = 65536;
630
631 /* Now we're ready to register. */
632 err = register_netdev(dev);
633 if (err)
634 goto out_free;
635
636 tnc_init(sp);
637
638 return 0;
639
640 out_free:
641 kfree(xbuff);
642 kfree(rbuff);
643
644 free_netdev(dev);
645
646 out:
647 return err;
648 }
649
650
651 /*
652 * Close down a 6pack channel.
653 * This means flushing out any pending queues, and then restoring the
654 * TTY line discipline to what it was before it got hooked to 6pack
655 * (which usually is TTY again).
656 */
657 static void sixpack_close(struct tty_struct *tty)
658 {
659 struct sixpack *sp;
660
661 write_lock_bh(&disc_data_lock);
662 sp = tty->disc_data;
663 tty->disc_data = NULL;
664 write_unlock_bh(&disc_data_lock);
665 if (!sp)
666 return;
667
668 /*
669 * We have now ensured that nobody can start using ap from now on, but
670 * we have to wait for all existing users to finish.
671 */
672 if (!refcount_dec_and_test(&sp->refcnt))
673 down(&sp->dead_sem);
674
675 /* We must stop the queue to avoid potentially scribbling
676 * on the free buffers. The sp->dead_sem is not sufficient
677 * to protect us from sp->xbuff access.
678 */
679 netif_stop_queue(sp->dev);
680
681 del_timer_sync(&sp->tx_t);
682 del_timer_sync(&sp->resync_t);
683
684 /* Free all 6pack frame buffers. */
685 kfree(sp->rbuff);
686 kfree(sp->xbuff);
687
688 unregister_netdev(sp->dev);
689 }
690
691 /* Perform I/O control on an active 6pack channel. */
692 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
693 unsigned int cmd, unsigned long arg)
694 {
695 struct sixpack *sp = sp_get(tty);
696 struct net_device *dev;
697 unsigned int tmp, err;
698
699 if (!sp)
700 return -ENXIO;
701 dev = sp->dev;
702
703 switch(cmd) {
704 case SIOCGIFNAME:
705 err = copy_to_user((void __user *) arg, dev->name,
706 strlen(dev->name) + 1) ? -EFAULT : 0;
707 break;
708
709 case SIOCGIFENCAP:
710 err = put_user(0, (int __user *) arg);
711 break;
712
713 case SIOCSIFENCAP:
714 if (get_user(tmp, (int __user *) arg)) {
715 err = -EFAULT;
716 break;
717 }
718
719 sp->mode = tmp;
720 dev->addr_len = AX25_ADDR_LEN;
721 dev->hard_header_len = AX25_KISS_HEADER_LEN +
722 AX25_MAX_HEADER_LEN + 3;
723 dev->type = ARPHRD_AX25;
724
725 err = 0;
726 break;
727
728 case SIOCSIFHWADDR: {
729 char addr[AX25_ADDR_LEN];
730
731 if (copy_from_user(&addr,
732 (void __user *) arg, AX25_ADDR_LEN)) {
733 err = -EFAULT;
734 break;
735 }
736
737 netif_tx_lock_bh(dev);
738 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
739 netif_tx_unlock_bh(dev);
740
741 err = 0;
742 break;
743 }
744
745 default:
746 err = tty_mode_ioctl(tty, file, cmd, arg);
747 }
748
749 sp_put(sp);
750
751 return err;
752 }
753
754 static struct tty_ldisc_ops sp_ldisc = {
755 .owner = THIS_MODULE,
756 .magic = TTY_LDISC_MAGIC,
757 .name = "6pack",
758 .open = sixpack_open,
759 .close = sixpack_close,
760 .ioctl = sixpack_ioctl,
761 .receive_buf = sixpack_receive_buf,
762 .write_wakeup = sixpack_write_wakeup,
763 };
764
765 /* Initialize 6pack control device -- register 6pack line discipline */
766
767 static const char msg_banner[] __initconst = KERN_INFO \
768 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
769 static const char msg_regfail[] __initconst = KERN_ERR \
770 "6pack: can't register line discipline (err = %d)\n";
771
772 static int __init sixpack_init_driver(void)
773 {
774 int status;
775
776 printk(msg_banner);
777
778 /* Register the provided line protocol discipline */
779 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
780 printk(msg_regfail, status);
781
782 return status;
783 }
784
785 static const char msg_unregfail[] = KERN_ERR \
786 "6pack: can't unregister line discipline (err = %d)\n";
787
788 static void __exit sixpack_exit_driver(void)
789 {
790 int ret;
791
792 if ((ret = tty_unregister_ldisc(N_6PACK)))
793 printk(msg_unregfail, ret);
794 }
795
796 /* encode an AX.25 packet into 6pack */
797
798 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
799 int length, unsigned char tx_delay)
800 {
801 int count = 0;
802 unsigned char checksum = 0, buf[400];
803 int raw_count = 0;
804
805 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
806 tx_buf_raw[raw_count++] = SIXP_SEOF;
807
808 buf[0] = tx_delay;
809 for (count = 1; count < length; count++)
810 buf[count] = tx_buf[count];
811
812 for (count = 0; count < length; count++)
813 checksum += buf[count];
814 buf[length] = (unsigned char) 0xff - checksum;
815
816 for (count = 0; count <= length; count++) {
817 if ((count % 3) == 0) {
818 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
819 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
820 } else if ((count % 3) == 1) {
821 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
822 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
823 } else {
824 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
825 tx_buf_raw[raw_count++] = (buf[count] >> 2);
826 }
827 }
828 if ((length % 3) != 2)
829 raw_count++;
830 tx_buf_raw[raw_count++] = SIXP_SEOF;
831 return raw_count;
832 }
833
834 /* decode 4 sixpack-encoded bytes into 3 data bytes */
835
836 static void decode_data(struct sixpack *sp, unsigned char inbyte)
837 {
838 unsigned char *buf;
839
840 if (sp->rx_count != 3) {
841 sp->raw_buf[sp->rx_count++] = inbyte;
842
843 return;
844 }
845
846 buf = sp->raw_buf;
847 sp->cooked_buf[sp->rx_count_cooked++] =
848 buf[0] | ((buf[1] << 2) & 0xc0);
849 sp->cooked_buf[sp->rx_count_cooked++] =
850 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
851 sp->cooked_buf[sp->rx_count_cooked++] =
852 (buf[2] & 0x03) | (inbyte << 2);
853 sp->rx_count = 0;
854 }
855
856 /* identify and execute a 6pack priority command byte */
857
858 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
859 {
860 int actual;
861
862 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
863
864 /* RX and DCD flags can only be set in the same prio command,
865 if the DCD flag has been set without the RX flag in the previous
866 prio command. If DCD has not been set before, something in the
867 transmission has gone wrong. In this case, RX and DCD are
868 cleared in order to prevent the decode_data routine from
869 reading further data that might be corrupt. */
870
871 if (((sp->status & SIXP_DCD_MASK) == 0) &&
872 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
873 if (sp->status != 1)
874 printk(KERN_DEBUG "6pack: protocol violation\n");
875 else
876 sp->status = 0;
877 cmd &= ~SIXP_RX_DCD_MASK;
878 }
879 sp->status = cmd & SIXP_PRIO_DATA_MASK;
880 } else { /* output watchdog char if idle */
881 if ((sp->status2 != 0) && (sp->duplex == 1)) {
882 sp->led_state = 0x70;
883 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
884 sp->tx_enable = 1;
885 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
886 sp->xleft -= actual;
887 sp->xhead += actual;
888 sp->led_state = 0x60;
889 sp->status2 = 0;
890
891 }
892 }
893
894 /* needed to trigger the TNC watchdog */
895 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
896
897 /* if the state byte has been received, the TNC is present,
898 so the resync timer can be reset. */
899
900 if (sp->tnc_state == TNC_IN_SYNC) {
901 del_timer(&sp->resync_t);
902 sp->resync_t.expires = jiffies + SIXP_INIT_RESYNC_TIMEOUT;
903 add_timer(&sp->resync_t);
904 }
905
906 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
907 }
908
909 /* identify and execute a standard 6pack command byte */
910
911 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
912 {
913 unsigned char checksum = 0, rest = 0;
914 short i;
915
916 switch (cmd & SIXP_CMD_MASK) { /* normal command */
917 case SIXP_SEOF:
918 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
919 if ((sp->status & SIXP_RX_DCD_MASK) ==
920 SIXP_RX_DCD_MASK) {
921 sp->led_state = 0x68;
922 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
923 }
924 } else {
925 sp->led_state = 0x60;
926 /* fill trailing bytes with zeroes */
927 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
928 rest = sp->rx_count;
929 if (rest != 0)
930 for (i = rest; i <= 3; i++)
931 decode_data(sp, 0);
932 if (rest == 2)
933 sp->rx_count_cooked -= 2;
934 else if (rest == 3)
935 sp->rx_count_cooked -= 1;
936 for (i = 0; i < sp->rx_count_cooked; i++)
937 checksum += sp->cooked_buf[i];
938 if (checksum != SIXP_CHKSUM) {
939 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
940 } else {
941 sp->rcount = sp->rx_count_cooked-2;
942 sp_bump(sp, 0);
943 }
944 sp->rx_count_cooked = 0;
945 }
946 break;
947 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
948 break;
949 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
950 break;
951 case SIXP_RX_BUF_OVL:
952 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
953 }
954 }
955
956 /* decode a 6pack packet */
957
958 static void
959 sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
960 {
961 unsigned char inbyte;
962 int count1;
963
964 for (count1 = 0; count1 < count; count1++) {
965 inbyte = pre_rbuff[count1];
966 if (inbyte == SIXP_FOUND_TNC) {
967 tnc_set_sync_state(sp, TNC_IN_SYNC);
968 del_timer(&sp->resync_t);
969 }
970 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
971 decode_prio_command(sp, inbyte);
972 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
973 decode_std_command(sp, inbyte);
974 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
975 decode_data(sp, inbyte);
976 }
977 }
978
979 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
980 MODULE_DESCRIPTION("6pack driver for AX.25");
981 MODULE_LICENSE("GPL");
982 MODULE_ALIAS_LDISC(N_6PACK);
983
984 module_init(sixpack_init_driver);
985 module_exit(sixpack_exit_driver);
Linux with added FPC-III support