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Merge tag 'for-linus-5.15b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel...
[mirror_ubuntu-jammy-kernel.git] / drivers / net / hamradio / 6pack.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * 6pack.c This module implements the 6pack protocol for kernel-based
4 * devices like TTY. It interfaces between a raw TTY and the
5 * kernel's AX.25 protocol layers.
6 *
7 * Authors: Andreas Könsgen <ajk@comnets.uni-bremen.de>
8 * Ralf Baechle DL5RB <ralf@linux-mips.org>
9 *
10 * Quite a lot of stuff "stolen" by Joerg Reuter from slip.c, written by
11 *
12 * Laurence Culhane, <loz@holmes.demon.co.uk>
13 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
14 */
15
16 #include <linux/module.h>
17 #include <linux/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 <linux/slab.h>
28 #include <net/ax25.h>
29 #include <linux/etherdevice.h>
30 #include <linux/skbuff.h>
31 #include <linux/rtnetlink.h>
32 #include <linux/spinlock.h>
33 #include <linux/if_arp.h>
34 #include <linux/init.h>
35 #include <linux/ip.h>
36 #include <linux/tcp.h>
37 #include <linux/semaphore.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 25 /* 250 ms */
72 #define SIXP_PERSIST 50 /* in 256ths */
73 #define SIXP_SLOTTIME 10 /* 100 ms */
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 completion dead;
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
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. */
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 (p[0] > 5) {
175 msg = "invalid KISS command";
176 goto out_drop;
177 }
178
179 if ((p[0] != 0) && (len > 2)) {
180 msg = "KISS control packet too long";
181 goto out_drop;
182 }
183
184 if ((p[0] == 0) && (len < 15)) {
185 msg = "bad AX.25 packet to transmit";
186 goto out_drop;
187 }
188
189 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
190 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
191
192 switch (p[0]) {
193 case 1: sp->tx_delay = p[1];
194 return;
195 case 2: sp->persistence = p[1];
196 return;
197 case 3: sp->slottime = p[1];
198 return;
199 case 4: /* ignored */
200 return;
201 case 5: sp->duplex = p[1];
202 return;
203 }
204
205 if (p[0] != 0)
206 return;
207
208 /*
209 * In case of fullduplex or DAMA operation, we don't take care about the
210 * state of the DCD or of any timers, as the determination of the
211 * correct time to send is the job of the AX.25 layer. We send
212 * immediately after data has arrived.
213 */
214 if (sp->duplex == 1) {
215 sp->led_state = 0x70;
216 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
217 sp->tx_enable = 1;
218 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
219 sp->xleft = count - actual;
220 sp->xhead = sp->xbuff + actual;
221 sp->led_state = 0x60;
222 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
223 } else {
224 sp->xleft = count;
225 sp->xhead = sp->xbuff;
226 sp->status2 = count;
227 sp_xmit_on_air(&sp->tx_t);
228 }
229
230 return;
231
232 out_drop:
233 sp->dev->stats.tx_dropped++;
234 netif_start_queue(sp->dev);
235 if (net_ratelimit())
236 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
237 }
238
239 /* Encapsulate an IP datagram and kick it into a TTY queue. */
240
241 static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
242 {
243 struct sixpack *sp = netdev_priv(dev);
244
245 if (skb->protocol == htons(ETH_P_IP))
246 return ax25_ip_xmit(skb);
247
248 spin_lock_bh(&sp->lock);
249 /* We were not busy, so we are now... :-) */
250 netif_stop_queue(dev);
251 dev->stats.tx_bytes += skb->len;
252 sp_encaps(sp, skb->data, skb->len);
253 spin_unlock_bh(&sp->lock);
254
255 dev_kfree_skb(skb);
256
257 return NETDEV_TX_OK;
258 }
259
260 static int sp_open_dev(struct net_device *dev)
261 {
262 struct sixpack *sp = netdev_priv(dev);
263
264 if (sp->tty == NULL)
265 return -ENODEV;
266 return 0;
267 }
268
269 /* Close the low-level part of the 6pack channel. */
270 static int sp_close(struct net_device *dev)
271 {
272 struct sixpack *sp = netdev_priv(dev);
273
274 spin_lock_bh(&sp->lock);
275 if (sp->tty) {
276 /* TTY discipline is running. */
277 clear_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
278 }
279 netif_stop_queue(dev);
280 spin_unlock_bh(&sp->lock);
281
282 return 0;
283 }
284
285 static int sp_set_mac_address(struct net_device *dev, void *addr)
286 {
287 struct sockaddr_ax25 *sa = addr;
288
289 netif_tx_lock_bh(dev);
290 netif_addr_lock(dev);
291 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN);
292 netif_addr_unlock(dev);
293 netif_tx_unlock_bh(dev);
294
295 return 0;
296 }
297
298 static const struct net_device_ops sp_netdev_ops = {
299 .ndo_open = sp_open_dev,
300 .ndo_stop = sp_close,
301 .ndo_start_xmit = sp_xmit,
302 .ndo_set_mac_address = sp_set_mac_address,
303 };
304
305 static void sp_setup(struct net_device *dev)
306 {
307 /* Finish setting up the DEVICE info. */
308 dev->netdev_ops = &sp_netdev_ops;
309 dev->needs_free_netdev = true;
310 dev->mtu = SIXP_MTU;
311 dev->hard_header_len = AX25_MAX_HEADER_LEN;
312 dev->header_ops = &ax25_header_ops;
313
314 dev->addr_len = AX25_ADDR_LEN;
315 dev->type = ARPHRD_AX25;
316 dev->tx_queue_len = 10;
317
318 /* Only activated in AX.25 mode */
319 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
320 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
321
322 dev->flags = 0;
323 }
324
325 /* Send one completely decapsulated IP datagram to the IP layer. */
326
327 /*
328 * This is the routine that sends the received data to the kernel AX.25.
329 * 'cmd' is the KISS command. For AX.25 data, it is zero.
330 */
331
332 static void sp_bump(struct sixpack *sp, char cmd)
333 {
334 struct sk_buff *skb;
335 int count;
336 unsigned char *ptr;
337
338 count = sp->rcount + 1;
339
340 sp->dev->stats.rx_bytes += count;
341
342 if ((skb = dev_alloc_skb(count + 1)) == NULL)
343 goto out_mem;
344
345 ptr = skb_put(skb, count + 1);
346 *ptr++ = cmd; /* KISS command */
347
348 memcpy(ptr, sp->cooked_buf + 1, count);
349 skb->protocol = ax25_type_trans(skb, sp->dev);
350 netif_rx(skb);
351 sp->dev->stats.rx_packets++;
352
353 return;
354
355 out_mem:
356 sp->dev->stats.rx_dropped++;
357 }
358
359
360 /* ----------------------------------------------------------------------- */
361
362 /*
363 * We have a potential race on dereferencing tty->disc_data, because the tty
364 * layer provides no locking at all - thus one cpu could be running
365 * sixpack_receive_buf while another calls sixpack_close, which zeroes
366 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The
367 * best way to fix this is to use a rwlock in the tty struct, but for now we
368 * use a single global rwlock for all ttys in ppp line discipline.
369 */
370 static DEFINE_RWLOCK(disc_data_lock);
371
372 static struct sixpack *sp_get(struct tty_struct *tty)
373 {
374 struct sixpack *sp;
375
376 read_lock(&disc_data_lock);
377 sp = tty->disc_data;
378 if (sp)
379 refcount_inc(&sp->refcnt);
380 read_unlock(&disc_data_lock);
381
382 return sp;
383 }
384
385 static void sp_put(struct sixpack *sp)
386 {
387 if (refcount_dec_and_test(&sp->refcnt))
388 complete(&sp->dead);
389 }
390
391 /*
392 * Called by the TTY driver when there's room for more data. If we have
393 * more packets to send, we send them here.
394 */
395 static void sixpack_write_wakeup(struct tty_struct *tty)
396 {
397 struct sixpack *sp = sp_get(tty);
398 int actual;
399
400 if (!sp)
401 return;
402 if (sp->xleft <= 0) {
403 /* Now serial buffer is almost free & we can start
404 * transmission of another packet */
405 sp->dev->stats.tx_packets++;
406 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
407 sp->tx_enable = 0;
408 netif_wake_queue(sp->dev);
409 goto out;
410 }
411
412 if (sp->tx_enable) {
413 actual = tty->ops->write(tty, sp->xhead, sp->xleft);
414 sp->xleft -= actual;
415 sp->xhead += actual;
416 }
417
418 out:
419 sp_put(sp);
420 }
421
422 /* ----------------------------------------------------------------------- */
423
424 /*
425 * Handle the 'receiver data ready' interrupt.
426 * This function is called by the tty module in the kernel when
427 * a block of 6pack data has been received, which can now be decapsulated
428 * and sent on to some IP layer for further processing.
429 */
430 static void sixpack_receive_buf(struct tty_struct *tty,
431 const unsigned char *cp, const char *fp, int count)
432 {
433 struct sixpack *sp;
434 int count1;
435
436 if (!count)
437 return;
438
439 sp = sp_get(tty);
440 if (!sp)
441 return;
442
443 /* Read the characters out of the buffer */
444 count1 = count;
445 while (count) {
446 count--;
447 if (fp && *fp++) {
448 if (!test_and_set_bit(SIXPF_ERROR, &sp->flags))
449 sp->dev->stats.rx_errors++;
450 continue;
451 }
452 }
453 sixpack_decode(sp, cp, count1);
454
455 sp_put(sp);
456 tty_unthrottle(tty);
457 }
458
459 /*
460 * Try to resync the TNC. Called by the resync timer defined in
461 * decode_prio_command
462 */
463
464 #define TNC_UNINITIALIZED 0
465 #define TNC_UNSYNC_STARTUP 1
466 #define TNC_UNSYNCED 2
467 #define TNC_IN_SYNC 3
468
469 static void __tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
470 {
471 char *msg;
472
473 switch (new_tnc_state) {
474 default: /* gcc oh piece-o-crap ... */
475 case TNC_UNSYNC_STARTUP:
476 msg = "Synchronizing with TNC";
477 break;
478 case TNC_UNSYNCED:
479 msg = "Lost synchronization with TNC\n";
480 break;
481 case TNC_IN_SYNC:
482 msg = "Found TNC";
483 break;
484 }
485
486 sp->tnc_state = new_tnc_state;
487 printk(KERN_INFO "%s: %s\n", sp->dev->name, msg);
488 }
489
490 static inline void tnc_set_sync_state(struct sixpack *sp, int new_tnc_state)
491 {
492 int old_tnc_state = sp->tnc_state;
493
494 if (old_tnc_state != new_tnc_state)
495 __tnc_set_sync_state(sp, new_tnc_state);
496 }
497
498 static void resync_tnc(struct timer_list *t)
499 {
500 struct sixpack *sp = from_timer(sp, t, resync_t);
501 static char resync_cmd = 0xe8;
502
503 /* clear any data that might have been received */
504
505 sp->rx_count = 0;
506 sp->rx_count_cooked = 0;
507
508 /* reset state machine */
509
510 sp->status = 1;
511 sp->status1 = 1;
512 sp->status2 = 0;
513
514 /* resync the TNC */
515
516 sp->led_state = 0x60;
517 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
518 sp->tty->ops->write(sp->tty, &resync_cmd, 1);
519
520
521 /* Start resync timer again -- the TNC might be still absent */
522 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
523 }
524
525 static inline int tnc_init(struct sixpack *sp)
526 {
527 unsigned char inbyte = 0xe8;
528
529 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
530
531 sp->tty->ops->write(sp->tty, &inbyte, 1);
532
533 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
534
535 return 0;
536 }
537
538 /*
539 * Open the high-level part of the 6pack channel.
540 * This function is called by the TTY module when the
541 * 6pack line discipline is called for. Because we are
542 * sure the tty line exists, we only have to link it to
543 * a free 6pcack channel...
544 */
545 static int sixpack_open(struct tty_struct *tty)
546 {
547 char *rbuff = NULL, *xbuff = NULL;
548 struct net_device *dev;
549 struct sixpack *sp;
550 unsigned long len;
551 int err = 0;
552
553 if (!capable(CAP_NET_ADMIN))
554 return -EPERM;
555 if (tty->ops->write == NULL)
556 return -EOPNOTSUPP;
557
558 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
559 sp_setup);
560 if (!dev) {
561 err = -ENOMEM;
562 goto out;
563 }
564
565 sp = netdev_priv(dev);
566 sp->dev = dev;
567
568 spin_lock_init(&sp->lock);
569 refcount_set(&sp->refcnt, 1);
570 init_completion(&sp->dead);
571
572 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
573
574 len = dev->mtu * 2;
575
576 rbuff = kmalloc(len + 4, GFP_KERNEL);
577 xbuff = kmalloc(len + 4, GFP_KERNEL);
578
579 if (rbuff == NULL || xbuff == NULL) {
580 err = -ENOBUFS;
581 goto out_free;
582 }
583
584 spin_lock_bh(&sp->lock);
585
586 sp->tty = tty;
587
588 sp->rbuff = rbuff;
589 sp->xbuff = xbuff;
590
591 sp->mtu = AX25_MTU + 73;
592 sp->buffsize = len;
593 sp->rcount = 0;
594 sp->rx_count = 0;
595 sp->rx_count_cooked = 0;
596 sp->xleft = 0;
597
598 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
599
600 sp->duplex = 0;
601 sp->tx_delay = SIXP_TXDELAY;
602 sp->persistence = SIXP_PERSIST;
603 sp->slottime = SIXP_SLOTTIME;
604 sp->led_state = 0x60;
605 sp->status = 1;
606 sp->status1 = 1;
607 sp->status2 = 0;
608 sp->tx_enable = 0;
609
610 netif_start_queue(dev);
611
612 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
613
614 timer_setup(&sp->resync_t, resync_tnc, 0);
615
616 spin_unlock_bh(&sp->lock);
617
618 /* Done. We have linked the TTY line to a channel. */
619 tty->disc_data = sp;
620 tty->receive_room = 65536;
621
622 /* Now we're ready to register. */
623 err = register_netdev(dev);
624 if (err)
625 goto out_free;
626
627 tnc_init(sp);
628
629 return 0;
630
631 out_free:
632 kfree(xbuff);
633 kfree(rbuff);
634
635 free_netdev(dev);
636
637 out:
638 return err;
639 }
640
641
642 /*
643 * Close down a 6pack channel.
644 * This means flushing out any pending queues, and then restoring the
645 * TTY line discipline to what it was before it got hooked to 6pack
646 * (which usually is TTY again).
647 */
648 static void sixpack_close(struct tty_struct *tty)
649 {
650 struct sixpack *sp;
651
652 write_lock_irq(&disc_data_lock);
653 sp = tty->disc_data;
654 tty->disc_data = NULL;
655 write_unlock_irq(&disc_data_lock);
656 if (!sp)
657 return;
658
659 /*
660 * We have now ensured that nobody can start using ap from now on, but
661 * we have to wait for all existing users to finish.
662 */
663 if (!refcount_dec_and_test(&sp->refcnt))
664 wait_for_completion(&sp->dead);
665
666 /* We must stop the queue to avoid potentially scribbling
667 * on the free buffers. The sp->dead completion is not sufficient
668 * to protect us from sp->xbuff access.
669 */
670 netif_stop_queue(sp->dev);
671
672 del_timer_sync(&sp->tx_t);
673 del_timer_sync(&sp->resync_t);
674
675 /* Free all 6pack frame buffers. */
676 kfree(sp->rbuff);
677 kfree(sp->xbuff);
678
679 unregister_netdev(sp->dev);
680 }
681
682 /* Perform I/O control on an active 6pack channel. */
683 static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
684 unsigned int cmd, unsigned long arg)
685 {
686 struct sixpack *sp = sp_get(tty);
687 struct net_device *dev;
688 unsigned int tmp, err;
689
690 if (!sp)
691 return -ENXIO;
692 dev = sp->dev;
693
694 switch(cmd) {
695 case SIOCGIFNAME:
696 err = copy_to_user((void __user *) arg, dev->name,
697 strlen(dev->name) + 1) ? -EFAULT : 0;
698 break;
699
700 case SIOCGIFENCAP:
701 err = put_user(0, (int __user *) arg);
702 break;
703
704 case SIOCSIFENCAP:
705 if (get_user(tmp, (int __user *) arg)) {
706 err = -EFAULT;
707 break;
708 }
709
710 sp->mode = tmp;
711 dev->addr_len = AX25_ADDR_LEN;
712 dev->hard_header_len = AX25_KISS_HEADER_LEN +
713 AX25_MAX_HEADER_LEN + 3;
714 dev->type = ARPHRD_AX25;
715
716 err = 0;
717 break;
718
719 case SIOCSIFHWADDR: {
720 char addr[AX25_ADDR_LEN];
721
722 if (copy_from_user(&addr,
723 (void __user *)arg, AX25_ADDR_LEN)) {
724 err = -EFAULT;
725 break;
726 }
727
728 netif_tx_lock_bh(dev);
729 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
730 netif_tx_unlock_bh(dev);
731 err = 0;
732 break;
733 }
734 default:
735 err = tty_mode_ioctl(tty, file, cmd, arg);
736 }
737
738 sp_put(sp);
739
740 return err;
741 }
742
743 static struct tty_ldisc_ops sp_ldisc = {
744 .owner = THIS_MODULE,
745 .num = N_6PACK,
746 .name = "6pack",
747 .open = sixpack_open,
748 .close = sixpack_close,
749 .ioctl = sixpack_ioctl,
750 .receive_buf = sixpack_receive_buf,
751 .write_wakeup = sixpack_write_wakeup,
752 };
753
754 /* Initialize 6pack control device -- register 6pack line discipline */
755
756 static const char msg_banner[] __initconst = KERN_INFO \
757 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
758 static const char msg_regfail[] __initconst = KERN_ERR \
759 "6pack: can't register line discipline (err = %d)\n";
760
761 static int __init sixpack_init_driver(void)
762 {
763 int status;
764
765 printk(msg_banner);
766
767 /* Register the provided line protocol discipline */
768 status = tty_register_ldisc(&sp_ldisc);
769 if (status)
770 printk(msg_regfail, status);
771
772 return status;
773 }
774
775 static void __exit sixpack_exit_driver(void)
776 {
777 tty_unregister_ldisc(&sp_ldisc);
778 }
779
780 /* encode an AX.25 packet into 6pack */
781
782 static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
783 int length, unsigned char tx_delay)
784 {
785 int count = 0;
786 unsigned char checksum = 0, buf[400];
787 int raw_count = 0;
788
789 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
790 tx_buf_raw[raw_count++] = SIXP_SEOF;
791
792 buf[0] = tx_delay;
793 for (count = 1; count < length; count++)
794 buf[count] = tx_buf[count];
795
796 for (count = 0; count < length; count++)
797 checksum += buf[count];
798 buf[length] = (unsigned char) 0xff - checksum;
799
800 for (count = 0; count <= length; count++) {
801 if ((count % 3) == 0) {
802 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
803 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
804 } else if ((count % 3) == 1) {
805 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
806 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
807 } else {
808 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
809 tx_buf_raw[raw_count++] = (buf[count] >> 2);
810 }
811 }
812 if ((length % 3) != 2)
813 raw_count++;
814 tx_buf_raw[raw_count++] = SIXP_SEOF;
815 return raw_count;
816 }
817
818 /* decode 4 sixpack-encoded bytes into 3 data bytes */
819
820 static void decode_data(struct sixpack *sp, unsigned char inbyte)
821 {
822 unsigned char *buf;
823
824 if (sp->rx_count != 3) {
825 sp->raw_buf[sp->rx_count++] = inbyte;
826
827 return;
828 }
829
830 if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) {
831 pr_err("6pack: cooked buffer overrun, data loss\n");
832 sp->rx_count = 0;
833 return;
834 }
835
836 buf = sp->raw_buf;
837 sp->cooked_buf[sp->rx_count_cooked++] =
838 buf[0] | ((buf[1] << 2) & 0xc0);
839 sp->cooked_buf[sp->rx_count_cooked++] =
840 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
841 sp->cooked_buf[sp->rx_count_cooked++] =
842 (buf[2] & 0x03) | (inbyte << 2);
843 sp->rx_count = 0;
844 }
845
846 /* identify and execute a 6pack priority command byte */
847
848 static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
849 {
850 int actual;
851
852 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
853
854 /* RX and DCD flags can only be set in the same prio command,
855 if the DCD flag has been set without the RX flag in the previous
856 prio command. If DCD has not been set before, something in the
857 transmission has gone wrong. In this case, RX and DCD are
858 cleared in order to prevent the decode_data routine from
859 reading further data that might be corrupt. */
860
861 if (((sp->status & SIXP_DCD_MASK) == 0) &&
862 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
863 if (sp->status != 1)
864 printk(KERN_DEBUG "6pack: protocol violation\n");
865 else
866 sp->status = 0;
867 cmd &= ~SIXP_RX_DCD_MASK;
868 }
869 sp->status = cmd & SIXP_PRIO_DATA_MASK;
870 } else { /* output watchdog char if idle */
871 if ((sp->status2 != 0) && (sp->duplex == 1)) {
872 sp->led_state = 0x70;
873 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
874 sp->tx_enable = 1;
875 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
876 sp->xleft -= actual;
877 sp->xhead += actual;
878 sp->led_state = 0x60;
879 sp->status2 = 0;
880
881 }
882 }
883
884 /* needed to trigger the TNC watchdog */
885 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
886
887 /* if the state byte has been received, the TNC is present,
888 so the resync timer can be reset. */
889
890 if (sp->tnc_state == TNC_IN_SYNC)
891 mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
892
893 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
894 }
895
896 /* identify and execute a standard 6pack command byte */
897
898 static void decode_std_command(struct sixpack *sp, unsigned char cmd)
899 {
900 unsigned char checksum = 0, rest = 0;
901 short i;
902
903 switch (cmd & SIXP_CMD_MASK) { /* normal command */
904 case SIXP_SEOF:
905 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
906 if ((sp->status & SIXP_RX_DCD_MASK) ==
907 SIXP_RX_DCD_MASK) {
908 sp->led_state = 0x68;
909 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
910 }
911 } else {
912 sp->led_state = 0x60;
913 /* fill trailing bytes with zeroes */
914 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
915 rest = sp->rx_count;
916 if (rest != 0)
917 for (i = rest; i <= 3; i++)
918 decode_data(sp, 0);
919 if (rest == 2)
920 sp->rx_count_cooked -= 2;
921 else if (rest == 3)
922 sp->rx_count_cooked -= 1;
923 for (i = 0; i < sp->rx_count_cooked; i++)
924 checksum += sp->cooked_buf[i];
925 if (checksum != SIXP_CHKSUM) {
926 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
927 } else {
928 sp->rcount = sp->rx_count_cooked-2;
929 sp_bump(sp, 0);
930 }
931 sp->rx_count_cooked = 0;
932 }
933 break;
934 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
935 break;
936 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
937 break;
938 case SIXP_RX_BUF_OVL:
939 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
940 }
941 }
942
943 /* decode a 6pack packet */
944
945 static void
946 sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
947 {
948 unsigned char inbyte;
949 int count1;
950
951 for (count1 = 0; count1 < count; count1++) {
952 inbyte = pre_rbuff[count1];
953 if (inbyte == SIXP_FOUND_TNC) {
954 tnc_set_sync_state(sp, TNC_IN_SYNC);
955 del_timer(&sp->resync_t);
956 }
957 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
958 decode_prio_command(sp, inbyte);
959 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
960 decode_std_command(sp, inbyte);
961 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
962 decode_data(sp, inbyte);
963 }
964 }
965
966 MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
967 MODULE_DESCRIPTION("6pack driver for AX.25");
968 MODULE_LICENSE("GPL");
969 MODULE_ALIAS_LDISC(N_6PACK);
970
971 module_init(sixpack_init_driver);
972 module_exit(sixpack_exit_driver);
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