aboutsummaryrefslogtreecommitdiff
path: root/drivers/net/hamradio/hdlcdrv.c
blob: c67a27245072746c3275a3b27a4fd899ebb6f3a4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
/*****************************************************************************/

/*
 *	hdlcdrv.c  -- HDLC packet radio network driver.
 *
 *	Copyright (C) 1996-2000  Thomas Sailer (sailer@ife.ee.ethz.ch)
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 *
 *	This program is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *	GNU General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License
 *	along with this program; if not, write to the Free Software
 *	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *  Please note that the GPL allows you to use the driver, NOT the radio.
 *  In order to use the radio, you need a license from the communications
 *  authority of your country.
 *
 *  The driver was derived from Donald Beckers skeleton.c
 *	Written 1993-94 by Donald Becker.
 *
 *  History:
 *   0.1  21.09.1996  Started
 *        18.10.1996  Changed to new user space access routines 
 *                    (copy_{to,from}_user)
 *   0.2  21.11.1996  various small changes
 *   0.3  03.03.1997  fixed (hopefully) IP not working with ax.25 as a module
 *   0.4  16.04.1997  init code/data tagged
 *   0.5  30.07.1997  made HDLC buffers bigger (solves a problem with the
 *                    soundmodem driver)
 *   0.6  05.04.1998  add spinlocks
 *   0.7  03.08.1999  removed some old compatibility cruft
 *   0.8  12.02.2000  adapted to softnet driver interface
 */

/*****************************************************************************/

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/if.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/bitops.h>

#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/hdlcdrv.h>
#include <linux/random.h>
#include <net/ax25.h> 
#include <asm/uaccess.h>

#include <linux/crc-ccitt.h>

/* --------------------------------------------------------------------- */

#define KISS_VERBOSE

/* --------------------------------------------------------------------- */

#define PARAM_TXDELAY   1
#define PARAM_PERSIST   2
#define PARAM_SLOTTIME  3
#define PARAM_TXTAIL    4
#define PARAM_FULLDUP   5
#define PARAM_HARDWARE  6
#define PARAM_RETURN    255

/* --------------------------------------------------------------------- */
/*
 * the CRC routines are stolen from WAMPES
 * by Dieter Deyke
 */


/*---------------------------------------------------------------------------*/

static inline void append_crc_ccitt(unsigned char *buffer, int len)
{
 	unsigned int crc = crc_ccitt(0xffff, buffer, len) ^ 0xffff;
	buffer += len;
	*buffer++ = crc;
	*buffer++ = crc >> 8;
}

/*---------------------------------------------------------------------------*/

static inline int check_crc_ccitt(const unsigned char *buf, int cnt)
{
	return (crc_ccitt(0xffff, buf, cnt) & 0xffff) == 0xf0b8;
}

/*---------------------------------------------------------------------------*/

#if 0
static int calc_crc_ccitt(const unsigned char *buf, int cnt)
{
	unsigned int crc = 0xffff;

	for (; cnt > 0; cnt--)
		crc = (crc >> 8) ^ crc_ccitt_table[(crc ^ *buf++) & 0xff];
	crc ^= 0xffff;
	return crc & 0xffff;
}
#endif

/* ---------------------------------------------------------------------- */

#define tenms_to_2flags(s,tenms) ((tenms * s->par.bitrate) / 100 / 16)

/* ---------------------------------------------------------------------- */
/*
 * The HDLC routines
 */

static int hdlc_rx_add_bytes(struct hdlcdrv_state *s, unsigned int bits, 
			     int num)
{
	int added = 0;
	
	while (s->hdlcrx.rx_state && num >= 8) {
		if (s->hdlcrx.len >= sizeof(s->hdlcrx.buffer)) {
			s->hdlcrx.rx_state = 0;
			return 0;
		}
		*s->hdlcrx.bp++ = bits >> (32-num);
		s->hdlcrx.len++;
		num -= 8;
		added += 8;
	}
	return added;
}

static void hdlc_rx_flag(struct net_device *dev, struct hdlcdrv_state *s)
{
	struct sk_buff *skb;
	int pkt_len;
	unsigned char *cp;

	if (s->hdlcrx.len < 4) 
		return;
	if (!check_crc_ccitt(s->hdlcrx.buffer, s->hdlcrx.len)) 
		return;
	pkt_len = s->hdlcrx.len - 2 + 1; /* KISS kludge */
	if (!(skb = dev_alloc_skb(pkt_len))) {
		printk("%s: memory squeeze, dropping packet\n", dev->name);
		dev->stats.rx_dropped++;
		return;
	}
	cp = skb_put(skb, pkt_len);
	*cp++ = 0; /* KISS kludge */
	memcpy(cp, s->hdlcrx.buffer, pkt_len - 1);
	skb->protocol = ax25_type_trans(skb, dev);
	netif_rx(skb);
	dev->stats.rx_packets++;
}

void hdlcdrv_receiver(struct net_device *dev, struct hdlcdrv_state *s)
{
	int i;
	unsigned int mask1, mask2, mask3, mask4, mask5, mask6, word;
	
	if (!s || s->magic != HDLCDRV_MAGIC) 
		return;
	if (test_and_set_bit(0, &s->hdlcrx.in_hdlc_rx))
		return;

	while (!hdlcdrv_hbuf_empty(&s->hdlcrx.hbuf)) {
		word = hdlcdrv_hbuf_get(&s->hdlcrx.hbuf);	

#ifdef HDLCDRV_DEBUG
		hdlcdrv_add_bitbuffer_word(&s->bitbuf_hdlc, word);
#endif /* HDLCDRV_DEBUG */
	       	s->hdlcrx.bitstream >>= 16;
		s->hdlcrx.bitstream |= word << 16;
		s->hdlcrx.bitbuf >>= 16;
		s->hdlcrx.bitbuf |= word << 16;
		s->hdlcrx.numbits += 16;
		for(i = 15, mask1 = 0x1fc00, mask2 = 0x1fe00, mask3 = 0x0fc00,
		    mask4 = 0x1f800, mask5 = 0xf800, mask6 = 0xffff; 
		    i >= 0; 
		    i--, mask1 <<= 1, mask2 <<= 1, mask3 <<= 1, mask4 <<= 1, 
		    mask5 <<= 1, mask6 = (mask6 << 1) | 1) {
			if ((s->hdlcrx.bitstream & mask1) == mask1)
				s->hdlcrx.rx_state = 0; /* abort received */
			else if ((s->hdlcrx.bitstream & mask2) == mask3) {
				/* flag received */
				if (s->hdlcrx.rx_state) {
					hdlc_rx_add_bytes(s, s->hdlcrx.bitbuf 
							  << (8+i),
							  s->hdlcrx.numbits
							  -8-i);
					hdlc_rx_flag(dev, s);
				}
				s->hdlcrx.len = 0;
				s->hdlcrx.bp = s->hdlcrx.buffer;
				s->hdlcrx.rx_state = 1;
				s->hdlcrx.numbits = i;
			} else if ((s->hdlcrx.bitstream & mask4) == mask5) {
				/* stuffed bit */
				s->hdlcrx.numbits--;
				s->hdlcrx.bitbuf = (s->hdlcrx.bitbuf & (~mask6)) |
					((s->hdlcrx.bitbuf & mask6) << 1);
			}
		}
		s->hdlcrx.numbits -= hdlc_rx_add_bytes(s, s->hdlcrx.bitbuf,
						       s->hdlcrx.numbits);
	}
	clear_bit(0, &s->hdlcrx.in_hdlc_rx);
}

/* ---------------------------------------------------------------------- */

static inline void do_kiss_params(struct hdlcdrv_state *s,
				  unsigned char *data, unsigned long len)
{

#ifdef KISS_VERBOSE
#define PKP(a,b) printk(KERN_INFO "hdlcdrv.c: channel params: " a "\n", b)
#else /* KISS_VERBOSE */	      
#define PKP(a,b) 
#endif /* KISS_VERBOSE */	      

	if (len < 2)
		return;
	switch(data[0]) {
	case PARAM_TXDELAY:
		s->ch_params.tx_delay = data[1];
		PKP("TX delay = %ums", 10 * s->ch_params.tx_delay);
		break;
	case PARAM_PERSIST:   
		s->ch_params.ppersist = data[1];
		PKP("p persistence = %u", s->ch_params.ppersist);
		break;
	case PARAM_SLOTTIME:  
		s->ch_params.slottime = data[1];
		PKP("slot time = %ums", s->ch_params.slottime);
		break;
	case PARAM_TXTAIL:    
		s->ch_params.tx_tail = data[1];
		PKP("TX tail = %ums", s->ch_params.tx_tail);
		break;
	case PARAM_FULLDUP:   
		s->ch_params.fulldup = !!data[1];
		PKP("%s duplex", s->ch_params.fulldup ? "full" : "half");
		break;
	default:
		break;
	}
#undef PKP
}

/* ---------------------------------------------------------------------- */

void hdlcdrv_transmitter(struct net_device *dev, struct hdlcdrv_state *s)
{
	unsigned int mask1, mask2, mask3;
	int i;
	struct sk_buff *skb;
	int pkt_len;

	if (!s || s->magic != HDLCDRV_MAGIC) 
		return;
	if (test_and_set_bit(0, &s->hdlctx.in_hdlc_tx))
		return;
	for (;;) {
		if (s->hdlctx.numbits >= 16) {
			if (hdlcdrv_hbuf_full(&s->hdlctx.hbuf)) {
				clear_bit(0, &s->hdlctx.in_hdlc_tx);
				return;
			}
			hdlcdrv_hbuf_put(&s->hdlctx.hbuf, s->hdlctx.bitbuf);
			s->hdlctx.bitbuf >>= 16;
			s->hdlctx.numbits -= 16;
		}
		switch (s->hdlctx.tx_state) {
		default:
			clear_bit(0, &s->hdlctx.in_hdlc_tx);
			return;
		case 0:
		case 1:
			if (s->hdlctx.numflags) {
				s->hdlctx.numflags--;
				s->hdlctx.bitbuf |= 
					0x7e7e << s->hdlctx.numbits;
				s->hdlctx.numbits += 16;
				break;
			}
			if (s->hdlctx.tx_state == 1) {
				clear_bit(0, &s->hdlctx.in_hdlc_tx);
				return;
			}
			if (!(skb = s->skb)) {
				int flgs = tenms_to_2flags(s, s->ch_params.tx_tail);
				if (flgs < 2)
					flgs = 2;
				s->hdlctx.tx_state = 1;
				s->hdlctx.numflags = flgs;
				break;
			}
			s->skb = NULL;
			netif_wake_queue(dev);
			pkt_len = skb->len-1; /* strip KISS byte */
			if (pkt_len >= HDLCDRV_MAXFLEN || pkt_len < 2) {
				s->hdlctx.tx_state = 0;
				s->hdlctx.numflags = 1;
				dev_kfree_skb_irq(skb);
				break;
			}
			skb_copy_from_linear_data_offset(skb, 1,
							 s->hdlctx.buffer,
							 pkt_len);
			dev_kfree_skb_irq(skb);
			s->hdlctx.bp = s->hdlctx.buffer;
			append_crc_ccitt(s->hdlctx.buffer, pkt_len);
			s->hdlctx.len = pkt_len+2; /* the appended CRC */
			s->hdlctx.tx_state = 2;
			s->hdlctx.bitstream = 0;
			dev->stats.tx_packets++;
			break;
		case 2:
			if (!s->hdlctx.len) {
				s->hdlctx.tx_state = 0;
				s->hdlctx.numflags = 1;
				break;
			}
			s->hdlctx.len--;
			s->hdlctx.bitbuf |= *s->hdlctx.bp <<
				s->hdlctx.numbits;
			s->hdlctx.bitstream >>= 8;
			s->hdlctx.bitstream |= (*s->hdlctx.bp++) << 16;
			mask1 = 0x1f000;
			mask2 = 0x10000;
			mask3 = 0xffffffff >> (31-s->hdlctx.numbits);
			s->hdlctx.numbits += 8;
			for(i = 0; i < 8; i++, mask1 <<= 1, mask2 <<= 1, 
			    mask3 = (mask3 << 1) | 1) {
				if ((s->hdlctx.bitstream & mask1) != mask1) 
					continue;
				s->hdlctx.bitstream &= ~mask2;
				s->hdlctx.bitbuf = 
					(s->hdlctx.bitbuf & mask3) |
						((s->hdlctx.bitbuf & 
						 (~mask3)) << 1);
				s->hdlctx.numbits++;
				mask3 = (mask3 << 1) | 1;
			}
			break;
		}
	}
}

/* ---------------------------------------------------------------------- */

static void start_tx(struct net_device *dev, struct hdlcdrv_state *s)
{
	s->hdlctx.tx_state = 0;
	s->hdlctx.numflags = tenms_to_2flags(s, s->ch_params.tx_delay);
	s->hdlctx.bitbuf = s->hdlctx.bitstream = s->hdlctx.numbits = 0;
	hdlcdrv_transmitter(dev, s);
	s->hdlctx.ptt = 1;
	s->ptt_keyed++;
}

/* ---------------------------------------------------------------------- */

void hdlcdrv_arbitrate(struct net_device *dev, struct hdlcdrv_state *s)
{
	if (!s || s->magic != HDLCDRV_MAGIC || s->hdlctx.ptt || !s->skb) 
		return;
	if (s->ch_params.fulldup) {
		start_tx(dev, s);
		return;
	}
	if (s->hdlcrx.dcd) {
		s->hdlctx.slotcnt = s->ch_params.slottime;
		return;
	}
	if ((--s->hdlctx.slotcnt) > 0)
		return;
	s->hdlctx.slotcnt = s->ch_params.slottime;
	if ((prandom_u32() % 256) > s->ch_params.ppersist)
		return;
	start_tx(dev, s);
}

/* --------------------------------------------------------------------- */
/*
 * ===================== network driver interface =========================
 */

static netdev_tx_t hdlcdrv_send_packet(struct sk_buff *skb,
				       struct net_device *dev)
{
	struct hdlcdrv_state *sm = netdev_priv(dev);

	if (skb->data[0] != 0) {
		do_kiss_params(sm, skb->data, skb->len);
		dev_kfree_skb(skb);
		return NETDEV_TX_OK;
	}
	if (sm->skb)
		return NETDEV_TX_LOCKED;
	netif_stop_queue(dev);
	sm->skb = skb;
	return NETDEV_TX_OK;
}

/* --------------------------------------------------------------------- */

static int hdlcdrv_set_mac_address(struct net_device *dev, void *addr)
{
	struct sockaddr *sa = (struct sockaddr *)addr;

	/* addr is an AX.25 shifted ASCII mac address */
	memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 
	return 0;                                         
}

/* --------------------------------------------------------------------- */
/*
 * Open/initialize the board. This is called (in the current kernel)
 * sometime after booting when the 'ifconfig' program is run.
 *
 * This routine should set everything up anew at each open, even
 * registers that "should" only need to be set once at boot, so that
 * there is non-reboot way to recover if something goes wrong.
 */

static int hdlcdrv_open(struct net_device *dev)
{
	struct hdlcdrv_state *s = netdev_priv(dev);
	int i;

	if (!s->ops || !s->ops->open)
		return -ENODEV;

	/*
	 * initialise some variables
	 */
	s->opened = 1;
	s->hdlcrx.hbuf.rd = s->hdlcrx.hbuf.wr = 0;
	s->hdlcrx.in_hdlc_rx = 0;
	s->hdlcrx.rx_state = 0;
	
	s->hdlctx.hbuf.rd = s->hdlctx.hbuf.wr = 0;
	s->hdlctx.in_hdlc_tx = 0;
	s->hdlctx.tx_state = 1;
	s->hdlctx.numflags = 0;
	s->hdlctx.bitstream = s->hdlctx.bitbuf = s->hdlctx.numbits = 0;
	s->hdlctx.ptt = 0;
	s->hdlctx.slotcnt = s->ch_params.slottime;
	s->hdlctx.calibrate = 0;

	i = s->ops->open(dev);
	if (i)
		return i;
	netif_start_queue(dev);
	return 0;
}

/* --------------------------------------------------------------------- */
/* 
 * The inverse routine to hdlcdrv_open(). 
 */

static int hdlcdrv_close(struct net_device *dev)
{
	struct hdlcdrv_state *s = netdev_priv(dev);
	int i = 0;

	netif_stop_queue(dev);

	if (s->ops && s->ops->close)
		i = s->ops->close(dev);
	if (s->skb)
		dev_kfree_skb(s->skb);
	s->skb = NULL;
	s->opened = 0;
	return i;
}

/* --------------------------------------------------------------------- */

static int hdlcdrv_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
	struct hdlcdrv_state *s = netdev_priv(dev);
	struct hdlcdrv_ioctl bi;

	if (cmd != SIOCDEVPRIVATE) {
		if (s->ops && s->ops->ioctl)
			return s->ops->ioctl(dev, ifr, &bi, cmd);
		return -ENOIOCTLCMD;
	}
	if (copy_from_user(&bi, ifr->ifr_data, sizeof(bi)))
		return -EFAULT;

	switch (bi.cmd) {
	default:
		if (s->ops && s->ops->ioctl)
			return s->ops->ioctl(dev, ifr, &bi, cmd);
		return -ENOIOCTLCMD;

	case HDLCDRVCTL_GETCHANNELPAR:
		bi.data.cp.tx_delay = s->ch_params.tx_delay;
		bi.data.cp.tx_tail = s->ch_params.tx_tail;
		bi.data.cp.slottime = s->ch_params.slottime;
		bi.data.cp.ppersist = s->ch_params.ppersist;
		bi.data.cp.fulldup = s->ch_params.fulldup;
		break;

	case HDLCDRVCTL_SETCHANNELPAR:
		if (!capable(CAP_NET_ADMIN))
			return -EACCES;
		s->ch_params.tx_delay = bi.data.cp.tx_delay;
		s->ch_params.tx_tail = bi.data.cp.tx_tail;
		s->ch_params.slottime = bi.data.cp.slottime;
		s->ch_params.ppersist = bi.data.cp.ppersist;
		s->ch_params.fulldup = bi.data.cp.fulldup;
		s->hdlctx.slotcnt = 1;
		return 0;
		
	case HDLCDRVCTL_GETMODEMPAR:
		bi.data.mp.iobase = dev->base_addr;
		bi.data.mp.irq = dev->irq;
		bi.data.mp.dma = dev->dma;
		bi.data.mp.dma2 = s->ptt_out.dma2;
		bi.data.mp.seriobase = s->ptt_out.seriobase;
		bi.data.mp.pariobase = s->ptt_out.pariobase;
		bi.data.mp.midiiobase = s->ptt_out.midiiobase;
		break;

	case HDLCDRVCTL_SETMODEMPAR:
		if ((!capable(CAP_SYS_RAWIO)) || netif_running(dev))
			return -EACCES;
		dev->base_addr = bi.data.mp.iobase;
		dev->irq = bi.data.mp.irq;
		dev->dma = bi.data.mp.dma;
		s->ptt_out.dma2 = bi.data.mp.dma2;
		s->ptt_out.seriobase = bi.data.mp.seriobase;
		s->ptt_out.pariobase = bi.data.mp.pariobase;
		s->ptt_out.midiiobase = bi.data.mp.midiiobase;
		return 0;	
	
	case HDLCDRVCTL_GETSTAT:
		bi.data.cs.ptt = hdlcdrv_ptt(s);
		bi.data.cs.dcd = s->hdlcrx.dcd;
		bi.data.cs.ptt_keyed = s->ptt_keyed;
		bi.data.cs.tx_packets = dev->stats.tx_packets;
		bi.data.cs.tx_errors = dev->stats.tx_errors;
		bi.data.cs.rx_packets = dev->stats.rx_packets;
		bi.data.cs.rx_errors = dev->stats.rx_errors;
		break;		

	case HDLCDRVCTL_OLDGETSTAT:
		bi.data.ocs.ptt = hdlcdrv_ptt(s);
		bi.data.ocs.dcd = s->hdlcrx.dcd;
		bi.data.ocs.ptt_keyed = s->ptt_keyed;
		break;		

	case HDLCDRVCTL_CALIBRATE:
		if(!capable(CAP_SYS_RAWIO))
			return -EPERM;
		if (bi.data.calibrate > INT_MAX / s->par.bitrate)
			return -EINVAL;
		s->hdlctx.calibrate = bi.data.calibrate * s->par.bitrate / 16;
		return 0;

	case HDLCDRVCTL_GETSAMPLES:
#ifndef HDLCDRV_DEBUG
		return -EPERM;
#else /* HDLCDRV_DEBUG */
		if (s->bitbuf_channel.rd == s->bitbuf_channel.wr) 
			return -EAGAIN;
		bi.data.bits = 
			s->bitbuf_channel.buffer[s->bitbuf_channel.rd];
		s->bitbuf_channel.rd = (s->bitbuf_channel.rd+1) %
			sizeof(s->bitbuf_channel.buffer);
		break;
#endif /* HDLCDRV_DEBUG */
				
	case HDLCDRVCTL_GETBITS:
#ifndef HDLCDRV_DEBUG
		return -EPERM;
#else /* HDLCDRV_DEBUG */
		if (s->bitbuf_hdlc.rd == s->bitbuf_hdlc.wr) 
			return -EAGAIN;
		bi.data.bits = 
			s->bitbuf_hdlc.buffer[s->bitbuf_hdlc.rd];
		s->bitbuf_hdlc.rd = (s->bitbuf_hdlc.rd+1) %
			sizeof(s->bitbuf_hdlc.buffer);
		break;		
#endif /* HDLCDRV_DEBUG */

	case HDLCDRVCTL_DRIVERNAME:
		if (s->ops && s->ops->drvname) {
			strncpy(bi.data.drivername, s->ops->drvname, 
				sizeof(bi.data.drivername));
			break;
		}
		bi.data.drivername[0] = '\0';
		break;
		
	}
	if (copy_to_user(ifr->ifr_data, &bi, sizeof(bi)))
		return -EFAULT;
	return 0;

}

/* --------------------------------------------------------------------- */

static const struct net_device_ops hdlcdrv_netdev = {
	.ndo_open	= hdlcdrv_open,
	.ndo_stop	= hdlcdrv_close,
	.ndo_start_xmit = hdlcdrv_send_packet,
	.ndo_do_ioctl	= hdlcdrv_ioctl,
	.ndo_set_mac_address = hdlcdrv_set_mac_address,
};

/*
 * Initialize fields in hdlcdrv
 */
static void hdlcdrv_setup(struct net_device *dev)
{
	static const struct hdlcdrv_channel_params dflt_ch_params = { 
		20, 2, 10, 40, 0 
	};
	struct hdlcdrv_state *s = netdev_priv(dev);

	/*
	 * initialize the hdlcdrv_state struct
	 */
	s->ch_params = dflt_ch_params;
	s->ptt_keyed = 0;

	spin_lock_init(&s->hdlcrx.hbuf.lock);
	s->hdlcrx.hbuf.rd = s->hdlcrx.hbuf.wr = 0;
	s->hdlcrx.in_hdlc_rx = 0;
	s->hdlcrx.rx_state = 0;
	
	spin_lock_init(&s->hdlctx.hbuf.lock);
	s->hdlctx.hbuf.rd = s->hdlctx.hbuf.wr = 0;
	s->hdlctx.in_hdlc_tx = 0;
	s->hdlctx.tx_state = 1;
	s->hdlctx.numflags = 0;
	s->hdlctx.bitstream = s->hdlctx.bitbuf = s->hdlctx.numbits = 0;
	s->hdlctx.ptt = 0;
	s->hdlctx.slotcnt = s->ch_params.slottime;
	s->hdlctx.calibrate = 0;

#ifdef HDLCDRV_DEBUG
	s->bitbuf_channel.rd = s->bitbuf_channel.wr = 0;
	s->bitbuf_channel.shreg = 0x80;

	s->bitbuf_hdlc.rd = s->bitbuf_hdlc.wr = 0;
	s->bitbuf_hdlc.shreg = 0x80;
#endif /* HDLCDRV_DEBUG */


	/* Fill in the fields of the device structure */

	s->skb = NULL;
	
	dev->netdev_ops = &hdlcdrv_netdev;
	dev->header_ops = &ax25_header_ops;
	
	dev->type = ARPHRD_AX25;           /* AF_AX25 device */
	dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
	dev->mtu = AX25_DEF_PACLEN;        /* eth_mtu is the default */
	dev->addr_len = AX25_ADDR_LEN;     /* sizeof an ax.25 address */
	memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
	memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN);
	dev->tx_queue_len = 16;
}

/* --------------------------------------------------------------------- */
struct net_device *hdlcdrv_register(const struct hdlcdrv_ops *ops,
				    unsigned int privsize, const char *ifname,
				    unsigned int baseaddr, unsigned int irq, 
				    unsigned int dma) 
{
	struct net_device *dev;
	struct hdlcdrv_state *s;
	int err;

	BUG_ON(ops == NULL);

	if (privsize < sizeof(struct hdlcdrv_state))
		privsize = sizeof(struct hdlcdrv_state);

	dev = alloc_netdev(privsize, ifname, NET_NAME_UNKNOWN, hdlcdrv_setup);
	if (!dev)
		return ERR_PTR(-ENOMEM);

	/*
	 * initialize part of the hdlcdrv_state struct
	 */
	s = netdev_priv(dev);
	s->magic = HDLCDRV_MAGIC;
	s->ops = ops;
	dev->base_addr = baseaddr;
	dev->irq = irq;
	dev->dma = dma;

	err = register_netdev(dev);
	if (err < 0) {
		printk(KERN_WARNING "hdlcdrv: cannot register net "
		       "device %s\n", dev->name);
		free_netdev(dev);
		dev = ERR_PTR(err);
	}
	return dev;
}

/* --------------------------------------------------------------------- */

void hdlcdrv_unregister(struct net_device *dev) 
{
	struct hdlcdrv_state *s = netdev_priv(dev);

	BUG_ON(s->magic != HDLCDRV_MAGIC);

	if (s->opened && s->ops->close)
		s->ops->close(dev);
	unregister_netdev(dev);
	
	free_netdev(dev);
}

/* --------------------------------------------------------------------- */

EXPORT_SYMBOL(hdlcdrv_receiver);
EXPORT_SYMBOL(hdlcdrv_transmitter);
EXPORT_SYMBOL(hdlcdrv_arbitrate);
EXPORT_SYMBOL(hdlcdrv_register);
EXPORT_SYMBOL(hdlcdrv_unregister);

/* --------------------------------------------------------------------- */

static int __init hdlcdrv_init_driver(void)
{
	printk(KERN_INFO "hdlcdrv: (C) 1996-2000 Thomas Sailer HB9JNX/AE4WA\n");
	printk(KERN_INFO "hdlcdrv: version 0.8\n");
	return 0;
}

/* --------------------------------------------------------------------- */

static void __exit hdlcdrv_cleanup_driver(void)
{
	printk(KERN_INFO "hdlcdrv: cleanup\n");
}

/* --------------------------------------------------------------------- */

MODULE_AUTHOR("Thomas M. Sailer, sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu");
MODULE_DESCRIPTION("Packet Radio network interface HDLC encoder/decoder");
MODULE_LICENSE("GPL");
module_init(hdlcdrv_init_driver);
module_exit(hdlcdrv_cleanup_driver);

/* --------------------------------------------------------------------- */