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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
81enum sixpack_flags {
82 SIXPF_ERROR, /* Parity, etc. error */
83};
84
85struct 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 spinlock_t rxlock;
103
104 int mtu; /* Our mtu (to spot changes!) */
105 int buffsize; /* Max buffers sizes */
106
107 unsigned long flags; /* Flag values/ mode etc */
108 unsigned char mode; /* 6pack mode */
109
110 /* 6pack stuff */
111 unsigned char tx_delay;
112 unsigned char persistence;
113 unsigned char slottime;
114 unsigned char duplex;
115 unsigned char led_state;
116 unsigned char status;
117 unsigned char status1;
118 unsigned char status2;
119 unsigned char tx_enable;
120 unsigned char tnc_state;
121
122 struct timer_list tx_t;
123 struct timer_list resync_t;
124 refcount_t refcnt;
125 struct completion dead;
126 spinlock_t lock;
127};
128
129#define AX25_6PACK_HEADER_LEN 0
130
131static void sixpack_decode(struct sixpack *, const unsigned char[], int);
132static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
133
134/*
135 * Perform the persistence/slottime algorithm for CSMA access. If the
136 * persistence check was successful, write the data to the serial driver.
137 * Note that in case of DAMA operation, the data is not sent here.
138 */
139
140static void sp_xmit_on_air(struct timer_list *t)
141{
142 struct sixpack *sp = from_timer(sp, t, tx_t);
143 int actual, when = sp->slottime;
144 static unsigned char random;
145
146 random = random * 17 + 41;
147
148 if (((sp->status1 & SIXP_DCD_MASK) == 0) && (random < sp->persistence)) {
149 sp->led_state = 0x70;
150 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
151 sp->tx_enable = 1;
152 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
153 sp->xleft -= actual;
154 sp->xhead += actual;
155 sp->led_state = 0x60;
156 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
157 sp->status2 = 0;
158 } else
159 mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
160}
161
162/* ----> 6pack timer interrupt handler and friends. <---- */
163
164/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
165static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
166{
167 unsigned char *msg, *p = icp;
168 int actual, count;
169
170 if (len > sp->mtu) { /* sp->mtu = AX25_MTU = max. PACLEN = 256 */
171 msg = "oversized transmit packet!";
172 goto out_drop;
173 }
174
175 if (p[0] > 5) {
176 msg = "invalid KISS command";
177 goto out_drop;
178 }
179
180 if ((p[0] != 0) && (len > 2)) {
181 msg = "KISS control packet too long";
182 goto out_drop;
183 }
184
185 if ((p[0] == 0) && (len < 15)) {
186 msg = "bad AX.25 packet to transmit";
187 goto out_drop;
188 }
189
190 count = encode_sixpack(p, sp->xbuff, len, sp->tx_delay);
191 set_bit(TTY_DO_WRITE_WAKEUP, &sp->tty->flags);
192
193 switch (p[0]) {
194 case 1: sp->tx_delay = p[1];
195 return;
196 case 2: sp->persistence = p[1];
197 return;
198 case 3: sp->slottime = p[1];
199 return;
200 case 4: /* ignored */
201 return;
202 case 5: sp->duplex = p[1];
203 return;
204 }
205
206 if (p[0] != 0)
207 return;
208
209 /*
210 * In case of fullduplex or DAMA operation, we don't take care about the
211 * state of the DCD or of any timers, as the determination of the
212 * correct time to send is the job of the AX.25 layer. We send
213 * immediately after data has arrived.
214 */
215 if (sp->duplex == 1) {
216 sp->led_state = 0x70;
217 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
218 sp->tx_enable = 1;
219 actual = sp->tty->ops->write(sp->tty, sp->xbuff, count);
220 sp->xleft = count - actual;
221 sp->xhead = sp->xbuff + actual;
222 sp->led_state = 0x60;
223 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
224 } else {
225 sp->xleft = count;
226 sp->xhead = sp->xbuff;
227 sp->status2 = count;
228 sp_xmit_on_air(&sp->tx_t);
229 }
230
231 return;
232
233out_drop:
234 sp->dev->stats.tx_dropped++;
235 netif_start_queue(sp->dev);
236 if (net_ratelimit())
237 printk(KERN_DEBUG "%s: %s - dropped.\n", sp->dev->name, msg);
238}
239
240/* Encapsulate an IP datagram and kick it into a TTY queue. */
241
242static netdev_tx_t sp_xmit(struct sk_buff *skb, struct net_device *dev)
243{
244 struct sixpack *sp = netdev_priv(dev);
245
246 if (skb->protocol == htons(ETH_P_IP))
247 return ax25_ip_xmit(skb);
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 NETDEV_TX_OK;
259}
260
261static 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. */
271static 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
286static int sp_set_mac_address(struct net_device *dev, void *addr)
287{
288 struct sockaddr_ax25 *sa = addr;
289
290 netif_tx_lock_bh(dev);
291 netif_addr_lock(dev);
292 __dev_addr_set(dev, &sa->sax25_call, AX25_ADDR_LEN);
293 netif_addr_unlock(dev);
294 netif_tx_unlock_bh(dev);
295
296 return 0;
297}
298
299static const struct net_device_ops sp_netdev_ops = {
300 .ndo_open = sp_open_dev,
301 .ndo_stop = sp_close,
302 .ndo_start_xmit = sp_xmit,
303 .ndo_set_mac_address = sp_set_mac_address,
304};
305
306static void sp_setup(struct net_device *dev)
307{
308 /* Finish setting up the DEVICE info. */
309 dev->netdev_ops = &sp_netdev_ops;
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 dev_addr_set(dev, (u8 *)&ax25_defaddr);
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
332static 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
355out_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 */
370static DEFINE_RWLOCK(disc_data_lock);
371
372static 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
385static 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 */
395static 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
418out:
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 */
430static void sixpack_receive_buf(struct tty_struct *tty, const u8 *cp,
431 const u8 *fp, size_t 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
469static 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
490static 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
498static 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
525static 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 */
545static 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 spin_lock_init(&sp->rxlock);
570 refcount_set(&sp->refcnt, 1);
571 init_completion(&sp->dead);
572
573 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
574
575 len = dev->mtu * 2;
576
577 rbuff = kmalloc(len + 4, GFP_KERNEL);
578 xbuff = kmalloc(len + 4, GFP_KERNEL);
579
580 if (rbuff == NULL || xbuff == NULL) {
581 err = -ENOBUFS;
582 goto out_free;
583 }
584
585 spin_lock_bh(&sp->lock);
586
587 sp->tty = tty;
588
589 sp->rbuff = rbuff;
590 sp->xbuff = xbuff;
591
592 sp->mtu = AX25_MTU + 73;
593 sp->buffsize = len;
594 sp->rcount = 0;
595 sp->rx_count = 0;
596 sp->rx_count_cooked = 0;
597 sp->xleft = 0;
598
599 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
600
601 sp->duplex = 0;
602 sp->tx_delay = SIXP_TXDELAY;
603 sp->persistence = SIXP_PERSIST;
604 sp->slottime = SIXP_SLOTTIME;
605 sp->led_state = 0x60;
606 sp->status = 1;
607 sp->status1 = 1;
608 sp->status2 = 0;
609 sp->tx_enable = 0;
610
611 netif_start_queue(dev);
612
613 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
614
615 timer_setup(&sp->resync_t, resync_tnc, 0);
616
617 spin_unlock_bh(&sp->lock);
618
619 /* Done. We have linked the TTY line to a channel. */
620 tty->disc_data = sp;
621 tty->receive_room = 65536;
622
623 /* Now we're ready to register. */
624 err = register_netdev(dev);
625 if (err)
626 goto out_free;
627
628 tnc_init(sp);
629
630 return 0;
631
632out_free:
633 kfree(xbuff);
634 kfree(rbuff);
635
636 free_netdev(dev);
637
638out:
639 return err;
640}
641
642
643/*
644 * Close down a 6pack channel.
645 * This means flushing out any pending queues, and then restoring the
646 * TTY line discipline to what it was before it got hooked to 6pack
647 * (which usually is TTY again).
648 */
649static void sixpack_close(struct tty_struct *tty)
650{
651 struct sixpack *sp;
652
653 write_lock_irq(&disc_data_lock);
654 sp = tty->disc_data;
655 tty->disc_data = NULL;
656 write_unlock_irq(&disc_data_lock);
657 if (!sp)
658 return;
659
660 /*
661 * We have now ensured that nobody can start using ap from now on, but
662 * we have to wait for all existing users to finish.
663 */
664 if (!refcount_dec_and_test(&sp->refcnt))
665 wait_for_completion(&sp->dead);
666
667 /* We must stop the queue to avoid potentially scribbling
668 * on the free buffers. The sp->dead completion is not sufficient
669 * to protect us from sp->xbuff access.
670 */
671 netif_stop_queue(sp->dev);
672
673 unregister_netdev(sp->dev);
674
675 del_timer_sync(&sp->tx_t);
676 del_timer_sync(&sp->resync_t);
677
678 /* Free all 6pack frame buffers after unreg. */
679 kfree(sp->rbuff);
680 kfree(sp->xbuff);
681
682 free_netdev(sp->dev);
683}
684
685/* Perform I/O control on an active 6pack channel. */
686static int sixpack_ioctl(struct tty_struct *tty, unsigned int cmd,
687 unsigned long arg)
688{
689 struct sixpack *sp = sp_get(tty);
690 struct net_device *dev;
691 unsigned int tmp, err;
692
693 if (!sp)
694 return -ENXIO;
695 dev = sp->dev;
696
697 switch(cmd) {
698 case SIOCGIFNAME:
699 err = copy_to_user((void __user *) arg, dev->name,
700 strlen(dev->name) + 1) ? -EFAULT : 0;
701 break;
702
703 case SIOCGIFENCAP:
704 err = put_user(0, (int __user *) arg);
705 break;
706
707 case SIOCSIFENCAP:
708 if (get_user(tmp, (int __user *) arg)) {
709 err = -EFAULT;
710 break;
711 }
712
713 sp->mode = tmp;
714 dev->addr_len = AX25_ADDR_LEN;
715 dev->hard_header_len = AX25_KISS_HEADER_LEN +
716 AX25_MAX_HEADER_LEN + 3;
717 dev->type = ARPHRD_AX25;
718
719 err = 0;
720 break;
721
722 case SIOCSIFHWADDR: {
723 char addr[AX25_ADDR_LEN];
724
725 if (copy_from_user(&addr,
726 (void __user *)arg, AX25_ADDR_LEN)) {
727 err = -EFAULT;
728 break;
729 }
730
731 netif_tx_lock_bh(dev);
732 __dev_addr_set(dev, &addr, AX25_ADDR_LEN);
733 netif_tx_unlock_bh(dev);
734 err = 0;
735 break;
736 }
737 default:
738 err = tty_mode_ioctl(tty, cmd, arg);
739 }
740
741 sp_put(sp);
742
743 return err;
744}
745
746static struct tty_ldisc_ops sp_ldisc = {
747 .owner = THIS_MODULE,
748 .num = N_6PACK,
749 .name = "6pack",
750 .open = sixpack_open,
751 .close = sixpack_close,
752 .ioctl = sixpack_ioctl,
753 .receive_buf = sixpack_receive_buf,
754 .write_wakeup = sixpack_write_wakeup,
755};
756
757/* Initialize 6pack control device -- register 6pack line discipline */
758
759static const char msg_banner[] __initconst = KERN_INFO \
760 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
761static const char msg_regfail[] __initconst = KERN_ERR \
762 "6pack: can't register line discipline (err = %d)\n";
763
764static int __init sixpack_init_driver(void)
765{
766 int status;
767
768 printk(msg_banner);
769
770 /* Register the provided line protocol discipline */
771 status = tty_register_ldisc(&sp_ldisc);
772 if (status)
773 printk(msg_regfail, status);
774
775 return status;
776}
777
778static void __exit sixpack_exit_driver(void)
779{
780 tty_unregister_ldisc(&sp_ldisc);
781}
782
783/* encode an AX.25 packet into 6pack */
784
785static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
786 int length, unsigned char tx_delay)
787{
788 int count = 0;
789 unsigned char checksum = 0, buf[400];
790 int raw_count = 0;
791
792 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
793 tx_buf_raw[raw_count++] = SIXP_SEOF;
794
795 buf[0] = tx_delay;
796 for (count = 1; count < length; count++)
797 buf[count] = tx_buf[count];
798
799 for (count = 0; count < length; count++)
800 checksum += buf[count];
801 buf[length] = (unsigned char) 0xff - checksum;
802
803 for (count = 0; count <= length; count++) {
804 if ((count % 3) == 0) {
805 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
806 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
807 } else if ((count % 3) == 1) {
808 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
809 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
810 } else {
811 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
812 tx_buf_raw[raw_count++] = (buf[count] >> 2);
813 }
814 }
815 if ((length % 3) != 2)
816 raw_count++;
817 tx_buf_raw[raw_count++] = SIXP_SEOF;
818 return raw_count;
819}
820
821/* decode 4 sixpack-encoded bytes into 3 data bytes */
822
823static void decode_data(struct sixpack *sp, unsigned char inbyte)
824{
825 unsigned char *buf;
826
827 if (sp->rx_count != 3) {
828 sp->raw_buf[sp->rx_count++] = inbyte;
829
830 return;
831 }
832
833 if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) {
834 pr_err("6pack: cooked buffer overrun, data loss\n");
835 sp->rx_count = 0;
836 return;
837 }
838
839 buf = sp->raw_buf;
840 sp->cooked_buf[sp->rx_count_cooked++] =
841 buf[0] | ((buf[1] << 2) & 0xc0);
842 sp->cooked_buf[sp->rx_count_cooked++] =
843 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
844 sp->cooked_buf[sp->rx_count_cooked++] =
845 (buf[2] & 0x03) | (inbyte << 2);
846 sp->rx_count = 0;
847}
848
849/* identify and execute a 6pack priority command byte */
850
851static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
852{
853 int actual;
854
855 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
856
857 /* RX and DCD flags can only be set in the same prio command,
858 if the DCD flag has been set without the RX flag in the previous
859 prio command. If DCD has not been set before, something in the
860 transmission has gone wrong. In this case, RX and DCD are
861 cleared in order to prevent the decode_data routine from
862 reading further data that might be corrupt. */
863
864 if (((sp->status & SIXP_DCD_MASK) == 0) &&
865 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
866 if (sp->status != 1)
867 printk(KERN_DEBUG "6pack: protocol violation\n");
868 else
869 sp->status = 0;
870 cmd &= ~SIXP_RX_DCD_MASK;
871 }
872 sp->status = cmd & SIXP_PRIO_DATA_MASK;
873 } else { /* output watchdog char if idle */
874 if ((sp->status2 != 0) && (sp->duplex == 1)) {
875 sp->led_state = 0x70;
876 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
877 sp->tx_enable = 1;
878 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
879 sp->xleft -= actual;
880 sp->xhead += actual;
881 sp->led_state = 0x60;
882 sp->status2 = 0;
883
884 }
885 }
886
887 /* needed to trigger the TNC watchdog */
888 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
889
890 /* if the state byte has been received, the TNC is present,
891 so the resync timer can be reset. */
892
893 if (sp->tnc_state == TNC_IN_SYNC)
894 mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
895
896 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
897}
898
899/* identify and execute a standard 6pack command byte */
900
901static void decode_std_command(struct sixpack *sp, unsigned char cmd)
902{
903 unsigned char checksum = 0, rest = 0;
904 short i;
905
906 switch (cmd & SIXP_CMD_MASK) { /* normal command */
907 case SIXP_SEOF:
908 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
909 if ((sp->status & SIXP_RX_DCD_MASK) ==
910 SIXP_RX_DCD_MASK) {
911 sp->led_state = 0x68;
912 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
913 }
914 } else {
915 sp->led_state = 0x60;
916 /* fill trailing bytes with zeroes */
917 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
918 spin_lock_bh(&sp->rxlock);
919 rest = sp->rx_count;
920 if (rest != 0)
921 for (i = rest; i <= 3; i++)
922 decode_data(sp, 0);
923 if (rest == 2)
924 sp->rx_count_cooked -= 2;
925 else if (rest == 3)
926 sp->rx_count_cooked -= 1;
927 for (i = 0; i < sp->rx_count_cooked; i++)
928 checksum += sp->cooked_buf[i];
929 if (checksum != SIXP_CHKSUM) {
930 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
931 } else {
932 sp->rcount = sp->rx_count_cooked-2;
933 sp_bump(sp, 0);
934 }
935 sp->rx_count_cooked = 0;
936 spin_unlock_bh(&sp->rxlock);
937 }
938 break;
939 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
940 break;
941 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
942 break;
943 case SIXP_RX_BUF_OVL:
944 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
945 }
946}
947
948/* decode a 6pack packet */
949
950static void
951sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
952{
953 unsigned char inbyte;
954 int count1;
955
956 for (count1 = 0; count1 < count; count1++) {
957 inbyte = pre_rbuff[count1];
958 if (inbyte == SIXP_FOUND_TNC) {
959 tnc_set_sync_state(sp, TNC_IN_SYNC);
960 del_timer(&sp->resync_t);
961 }
962 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
963 decode_prio_command(sp, inbyte);
964 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
965 decode_std_command(sp, inbyte);
966 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK) {
967 spin_lock_bh(&sp->rxlock);
968 decode_data(sp, inbyte);
969 spin_unlock_bh(&sp->rxlock);
970 }
971 }
972}
973
974MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
975MODULE_DESCRIPTION("6pack driver for AX.25");
976MODULE_LICENSE("GPL");
977MODULE_ALIAS_LDISC(N_6PACK);
978
979module_init(sixpack_init_driver);
980module_exit(sixpack_exit_driver);
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 (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
81enum sixpack_flags {
82 SIXPF_ERROR, /* Parity, etc. error */
83};
84
85struct 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
130static void sixpack_decode(struct sixpack *, const unsigned char[], int);
131static 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
139static 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. */
164static 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
237out_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
246static 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
265static 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. */
275static 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
290static 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
303static 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
310static 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
337static 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 + 1)) == NULL)
348 goto out_mem;
349
350 ptr = skb_put(skb, count + 1);
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
360out_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 */
375static DEFINE_RWLOCK(disc_data_lock);
376
377static 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
390static void sp_put(struct sixpack *sp)
391{
392 if (refcount_dec_and_test(&sp->refcnt))
393 complete(&sp->dead);
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 */
400static 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
423out:
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 */
435static 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
474static 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
495static 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
503static 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 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
528}
529
530static inline int tnc_init(struct sixpack *sp)
531{
532 unsigned char inbyte = 0xe8;
533
534 tnc_set_sync_state(sp, TNC_UNSYNC_STARTUP);
535
536 sp->tty->ops->write(sp->tty, &inbyte, 1);
537
538 mod_timer(&sp->resync_t, jiffies + SIXP_RESYNC_TIMEOUT);
539
540 return 0;
541}
542
543/*
544 * Open the high-level part of the 6pack channel.
545 * This function is called by the TTY module when the
546 * 6pack line discipline is called for. Because we are
547 * sure the tty line exists, we only have to link it to
548 * a free 6pcack channel...
549 */
550static int sixpack_open(struct tty_struct *tty)
551{
552 char *rbuff = NULL, *xbuff = NULL;
553 struct net_device *dev;
554 struct sixpack *sp;
555 unsigned long len;
556 int err = 0;
557
558 if (!capable(CAP_NET_ADMIN))
559 return -EPERM;
560 if (tty->ops->write == NULL)
561 return -EOPNOTSUPP;
562
563 dev = alloc_netdev(sizeof(struct sixpack), "sp%d", NET_NAME_UNKNOWN,
564 sp_setup);
565 if (!dev) {
566 err = -ENOMEM;
567 goto out;
568 }
569
570 sp = netdev_priv(dev);
571 sp->dev = dev;
572
573 spin_lock_init(&sp->lock);
574 refcount_set(&sp->refcnt, 1);
575 init_completion(&sp->dead);
576
577 /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
578
579 len = dev->mtu * 2;
580
581 rbuff = kmalloc(len + 4, GFP_KERNEL);
582 xbuff = kmalloc(len + 4, GFP_KERNEL);
583
584 if (rbuff == NULL || xbuff == NULL) {
585 err = -ENOBUFS;
586 goto out_free;
587 }
588
589 spin_lock_bh(&sp->lock);
590
591 sp->tty = tty;
592
593 sp->rbuff = rbuff;
594 sp->xbuff = xbuff;
595
596 sp->mtu = AX25_MTU + 73;
597 sp->buffsize = len;
598 sp->rcount = 0;
599 sp->rx_count = 0;
600 sp->rx_count_cooked = 0;
601 sp->xleft = 0;
602
603 sp->flags = 0; /* Clear ESCAPE & ERROR flags */
604
605 sp->duplex = 0;
606 sp->tx_delay = SIXP_TXDELAY;
607 sp->persistence = SIXP_PERSIST;
608 sp->slottime = SIXP_SLOTTIME;
609 sp->led_state = 0x60;
610 sp->status = 1;
611 sp->status1 = 1;
612 sp->status2 = 0;
613 sp->tx_enable = 0;
614
615 netif_start_queue(dev);
616
617 timer_setup(&sp->tx_t, sp_xmit_on_air, 0);
618
619 timer_setup(&sp->resync_t, resync_tnc, 0);
620
621 spin_unlock_bh(&sp->lock);
622
623 /* Done. We have linked the TTY line to a channel. */
624 tty->disc_data = sp;
625 tty->receive_room = 65536;
626
627 /* Now we're ready to register. */
628 err = register_netdev(dev);
629 if (err)
630 goto out_free;
631
632 tnc_init(sp);
633
634 return 0;
635
636out_free:
637 kfree(xbuff);
638 kfree(rbuff);
639
640 free_netdev(dev);
641
642out:
643 return err;
644}
645
646
647/*
648 * Close down a 6pack channel.
649 * This means flushing out any pending queues, and then restoring the
650 * TTY line discipline to what it was before it got hooked to 6pack
651 * (which usually is TTY again).
652 */
653static void sixpack_close(struct tty_struct *tty)
654{
655 struct sixpack *sp;
656
657 write_lock_bh(&disc_data_lock);
658 sp = tty->disc_data;
659 tty->disc_data = NULL;
660 write_unlock_bh(&disc_data_lock);
661 if (!sp)
662 return;
663
664 /*
665 * We have now ensured that nobody can start using ap from now on, but
666 * we have to wait for all existing users to finish.
667 */
668 if (!refcount_dec_and_test(&sp->refcnt))
669 wait_for_completion(&sp->dead);
670
671 /* We must stop the queue to avoid potentially scribbling
672 * on the free buffers. The sp->dead completion is not sufficient
673 * to protect us from sp->xbuff access.
674 */
675 netif_stop_queue(sp->dev);
676
677 del_timer_sync(&sp->tx_t);
678 del_timer_sync(&sp->resync_t);
679
680 /* Free all 6pack frame buffers. */
681 kfree(sp->rbuff);
682 kfree(sp->xbuff);
683
684 unregister_netdev(sp->dev);
685}
686
687/* Perform I/O control on an active 6pack channel. */
688static int sixpack_ioctl(struct tty_struct *tty, struct file *file,
689 unsigned int cmd, unsigned long arg)
690{
691 struct sixpack *sp = sp_get(tty);
692 struct net_device *dev;
693 unsigned int tmp, err;
694
695 if (!sp)
696 return -ENXIO;
697 dev = sp->dev;
698
699 switch(cmd) {
700 case SIOCGIFNAME:
701 err = copy_to_user((void __user *) arg, dev->name,
702 strlen(dev->name) + 1) ? -EFAULT : 0;
703 break;
704
705 case SIOCGIFENCAP:
706 err = put_user(0, (int __user *) arg);
707 break;
708
709 case SIOCSIFENCAP:
710 if (get_user(tmp, (int __user *) arg)) {
711 err = -EFAULT;
712 break;
713 }
714
715 sp->mode = tmp;
716 dev->addr_len = AX25_ADDR_LEN;
717 dev->hard_header_len = AX25_KISS_HEADER_LEN +
718 AX25_MAX_HEADER_LEN + 3;
719 dev->type = ARPHRD_AX25;
720
721 err = 0;
722 break;
723
724 case SIOCSIFHWADDR: {
725 char addr[AX25_ADDR_LEN];
726
727 if (copy_from_user(&addr,
728 (void __user *) arg, AX25_ADDR_LEN)) {
729 err = -EFAULT;
730 break;
731 }
732
733 netif_tx_lock_bh(dev);
734 memcpy(dev->dev_addr, &addr, AX25_ADDR_LEN);
735 netif_tx_unlock_bh(dev);
736
737 err = 0;
738 break;
739 }
740
741 default:
742 err = tty_mode_ioctl(tty, file, cmd, arg);
743 }
744
745 sp_put(sp);
746
747 return err;
748}
749
750static struct tty_ldisc_ops sp_ldisc = {
751 .owner = THIS_MODULE,
752 .magic = TTY_LDISC_MAGIC,
753 .name = "6pack",
754 .open = sixpack_open,
755 .close = sixpack_close,
756 .ioctl = sixpack_ioctl,
757 .receive_buf = sixpack_receive_buf,
758 .write_wakeup = sixpack_write_wakeup,
759};
760
761/* Initialize 6pack control device -- register 6pack line discipline */
762
763static const char msg_banner[] __initconst = KERN_INFO \
764 "AX.25: 6pack driver, " SIXPACK_VERSION "\n";
765static const char msg_regfail[] __initconst = KERN_ERR \
766 "6pack: can't register line discipline (err = %d)\n";
767
768static int __init sixpack_init_driver(void)
769{
770 int status;
771
772 printk(msg_banner);
773
774 /* Register the provided line protocol discipline */
775 if ((status = tty_register_ldisc(N_6PACK, &sp_ldisc)) != 0)
776 printk(msg_regfail, status);
777
778 return status;
779}
780
781static const char msg_unregfail[] = KERN_ERR \
782 "6pack: can't unregister line discipline (err = %d)\n";
783
784static void __exit sixpack_exit_driver(void)
785{
786 int ret;
787
788 if ((ret = tty_unregister_ldisc(N_6PACK)))
789 printk(msg_unregfail, ret);
790}
791
792/* encode an AX.25 packet into 6pack */
793
794static int encode_sixpack(unsigned char *tx_buf, unsigned char *tx_buf_raw,
795 int length, unsigned char tx_delay)
796{
797 int count = 0;
798 unsigned char checksum = 0, buf[400];
799 int raw_count = 0;
800
801 tx_buf_raw[raw_count++] = SIXP_PRIO_CMD_MASK | SIXP_TX_MASK;
802 tx_buf_raw[raw_count++] = SIXP_SEOF;
803
804 buf[0] = tx_delay;
805 for (count = 1; count < length; count++)
806 buf[count] = tx_buf[count];
807
808 for (count = 0; count < length; count++)
809 checksum += buf[count];
810 buf[length] = (unsigned char) 0xff - checksum;
811
812 for (count = 0; count <= length; count++) {
813 if ((count % 3) == 0) {
814 tx_buf_raw[raw_count++] = (buf[count] & 0x3f);
815 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x30);
816 } else if ((count % 3) == 1) {
817 tx_buf_raw[raw_count++] |= (buf[count] & 0x0f);
818 tx_buf_raw[raw_count] = ((buf[count] >> 2) & 0x3c);
819 } else {
820 tx_buf_raw[raw_count++] |= (buf[count] & 0x03);
821 tx_buf_raw[raw_count++] = (buf[count] >> 2);
822 }
823 }
824 if ((length % 3) != 2)
825 raw_count++;
826 tx_buf_raw[raw_count++] = SIXP_SEOF;
827 return raw_count;
828}
829
830/* decode 4 sixpack-encoded bytes into 3 data bytes */
831
832static void decode_data(struct sixpack *sp, unsigned char inbyte)
833{
834 unsigned char *buf;
835
836 if (sp->rx_count != 3) {
837 sp->raw_buf[sp->rx_count++] = inbyte;
838
839 return;
840 }
841
842 buf = sp->raw_buf;
843 sp->cooked_buf[sp->rx_count_cooked++] =
844 buf[0] | ((buf[1] << 2) & 0xc0);
845 sp->cooked_buf[sp->rx_count_cooked++] =
846 (buf[1] & 0x0f) | ((buf[2] << 2) & 0xf0);
847 sp->cooked_buf[sp->rx_count_cooked++] =
848 (buf[2] & 0x03) | (inbyte << 2);
849 sp->rx_count = 0;
850}
851
852/* identify and execute a 6pack priority command byte */
853
854static void decode_prio_command(struct sixpack *sp, unsigned char cmd)
855{
856 int actual;
857
858 if ((cmd & SIXP_PRIO_DATA_MASK) != 0) { /* idle ? */
859
860 /* RX and DCD flags can only be set in the same prio command,
861 if the DCD flag has been set without the RX flag in the previous
862 prio command. If DCD has not been set before, something in the
863 transmission has gone wrong. In this case, RX and DCD are
864 cleared in order to prevent the decode_data routine from
865 reading further data that might be corrupt. */
866
867 if (((sp->status & SIXP_DCD_MASK) == 0) &&
868 ((cmd & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)) {
869 if (sp->status != 1)
870 printk(KERN_DEBUG "6pack: protocol violation\n");
871 else
872 sp->status = 0;
873 cmd &= ~SIXP_RX_DCD_MASK;
874 }
875 sp->status = cmd & SIXP_PRIO_DATA_MASK;
876 } else { /* output watchdog char if idle */
877 if ((sp->status2 != 0) && (sp->duplex == 1)) {
878 sp->led_state = 0x70;
879 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
880 sp->tx_enable = 1;
881 actual = sp->tty->ops->write(sp->tty, sp->xbuff, sp->status2);
882 sp->xleft -= actual;
883 sp->xhead += actual;
884 sp->led_state = 0x60;
885 sp->status2 = 0;
886
887 }
888 }
889
890 /* needed to trigger the TNC watchdog */
891 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
892
893 /* if the state byte has been received, the TNC is present,
894 so the resync timer can be reset. */
895
896 if (sp->tnc_state == TNC_IN_SYNC)
897 mod_timer(&sp->resync_t, jiffies + SIXP_INIT_RESYNC_TIMEOUT);
898
899 sp->status1 = cmd & SIXP_PRIO_DATA_MASK;
900}
901
902/* identify and execute a standard 6pack command byte */
903
904static void decode_std_command(struct sixpack *sp, unsigned char cmd)
905{
906 unsigned char checksum = 0, rest = 0;
907 short i;
908
909 switch (cmd & SIXP_CMD_MASK) { /* normal command */
910 case SIXP_SEOF:
911 if ((sp->rx_count == 0) && (sp->rx_count_cooked == 0)) {
912 if ((sp->status & SIXP_RX_DCD_MASK) ==
913 SIXP_RX_DCD_MASK) {
914 sp->led_state = 0x68;
915 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
916 }
917 } else {
918 sp->led_state = 0x60;
919 /* fill trailing bytes with zeroes */
920 sp->tty->ops->write(sp->tty, &sp->led_state, 1);
921 rest = sp->rx_count;
922 if (rest != 0)
923 for (i = rest; i <= 3; i++)
924 decode_data(sp, 0);
925 if (rest == 2)
926 sp->rx_count_cooked -= 2;
927 else if (rest == 3)
928 sp->rx_count_cooked -= 1;
929 for (i = 0; i < sp->rx_count_cooked; i++)
930 checksum += sp->cooked_buf[i];
931 if (checksum != SIXP_CHKSUM) {
932 printk(KERN_DEBUG "6pack: bad checksum %2.2x\n", checksum);
933 } else {
934 sp->rcount = sp->rx_count_cooked-2;
935 sp_bump(sp, 0);
936 }
937 sp->rx_count_cooked = 0;
938 }
939 break;
940 case SIXP_TX_URUN: printk(KERN_DEBUG "6pack: TX underrun\n");
941 break;
942 case SIXP_RX_ORUN: printk(KERN_DEBUG "6pack: RX overrun\n");
943 break;
944 case SIXP_RX_BUF_OVL:
945 printk(KERN_DEBUG "6pack: RX buffer overflow\n");
946 }
947}
948
949/* decode a 6pack packet */
950
951static void
952sixpack_decode(struct sixpack *sp, const unsigned char *pre_rbuff, int count)
953{
954 unsigned char inbyte;
955 int count1;
956
957 for (count1 = 0; count1 < count; count1++) {
958 inbyte = pre_rbuff[count1];
959 if (inbyte == SIXP_FOUND_TNC) {
960 tnc_set_sync_state(sp, TNC_IN_SYNC);
961 del_timer(&sp->resync_t);
962 }
963 if ((inbyte & SIXP_PRIO_CMD_MASK) != 0)
964 decode_prio_command(sp, inbyte);
965 else if ((inbyte & SIXP_STD_CMD_MASK) != 0)
966 decode_std_command(sp, inbyte);
967 else if ((sp->status & SIXP_RX_DCD_MASK) == SIXP_RX_DCD_MASK)
968 decode_data(sp, inbyte);
969 }
970}
971
972MODULE_AUTHOR("Ralf Baechle DO1GRB <ralf@linux-mips.org>");
973MODULE_DESCRIPTION("6pack driver for AX.25");
974MODULE_LICENSE("GPL");
975MODULE_ALIAS_LDISC(N_6PACK);
976
977module_init(sixpack_init_driver);
978module_exit(sixpack_exit_driver);