summaryrefslogtreecommitdiffstats
path: root/drivers/isdn/i4l/isdn_v110.c
blob: 8b74ce412524827c14333e4444e275ac4fdcc723 (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
/* $Id: isdn_v110.c,v 1.1.2.2 2004/01/12 22:37:19 keil Exp $
 *
 * Linux ISDN subsystem, V.110 related functions (linklevel).
 *
 * Copyright by Thomas Pfeiffer (pfeiffer@pds.de)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 */

#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/delay.h>

#include <linux/isdn.h>
#include "isdn_v110.h"

#undef ISDN_V110_DEBUG

char *isdn_v110_revision = "$Revision: 1.1.2.2 $";

#define V110_38400 255
#define V110_19200  15
#define V110_9600    3

/*
 * The following data are precoded matrices, online and offline matrix
 * for 9600, 19200 und 38400, respectively
 */
static unsigned char V110_OnMatrix_9600[] =
{0xfc, 0xfc, 0xfc, 0xfc, 0xff, 0xff, 0xff, 0xfd, 0xff, 0xff,
 0xff, 0xfd, 0xff, 0xff, 0xff, 0xfd, 0xff, 0xff, 0xff, 0xfd,
 0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfd, 0xff, 0xff,
 0xff, 0xfd, 0xff, 0xff, 0xff, 0xfd, 0xff, 0xff, 0xff, 0xfd};

static unsigned char V110_OffMatrix_9600[] =
{0xfc, 0xfc, 0xfc, 0xfc, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};

static unsigned char V110_OnMatrix_19200[] =
{0xf0, 0xf0, 0xff, 0xf7, 0xff, 0xf7, 0xff, 0xf7, 0xff, 0xf7,
 0xfd, 0xff, 0xff, 0xf7, 0xff, 0xf7, 0xff, 0xf7, 0xff, 0xf7};

static unsigned char V110_OffMatrix_19200[] =
{0xf0, 0xf0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};

static unsigned char V110_OnMatrix_38400[] =
{0x00, 0x7f, 0x7f, 0x7f, 0x7f, 0xfd, 0x7f, 0x7f, 0x7f, 0x7f};

static unsigned char V110_OffMatrix_38400[] =
{0x00, 0xff, 0xff, 0xff, 0xff, 0xfd, 0xff, 0xff, 0xff, 0xff};

/*
 * FlipBits reorders sequences of keylen bits in one byte.
 * E.g. source order 7654321 will be converted to 45670123 when keylen = 4,
 * and to 67452301 when keylen = 2. This is necessary because ordering on
 * the isdn line is the other way.
 */
static inline unsigned char
FlipBits(unsigned char c, int keylen)
{
	unsigned char b = c;
	unsigned char bit = 128;
	int i;
	int j;
	int hunks = (8 / keylen);

	c = 0;
	for (i = 0; i < hunks; i++) {
		for (j = 0; j < keylen; j++) {
			if (b & (bit >> j))
				c |= bit >> (keylen - j - 1);
		}
		bit >>= keylen;
	}
	return c;
}


/* isdn_v110_open allocates and initializes private V.110 data
 * structures and returns a pointer to these.
 */
static isdn_v110_stream *
isdn_v110_open(unsigned char key, int hdrlen, int maxsize)
{
	int i;
	isdn_v110_stream *v;

	if ((v = kzalloc(sizeof(isdn_v110_stream), GFP_ATOMIC)) == NULL)
		return NULL;
	v->key = key;
	v->nbits = 0;
	for (i = 0; key & (1 << i); i++)
		v->nbits++;

	v->nbytes = 8 / v->nbits;
	v->decodelen = 0;

	switch (key) {
	case V110_38400:
		v->OnlineFrame = V110_OnMatrix_38400;
		v->OfflineFrame = V110_OffMatrix_38400;
		break;
	case V110_19200:
		v->OnlineFrame = V110_OnMatrix_19200;
		v->OfflineFrame = V110_OffMatrix_19200;
		break;
	default:
		v->OnlineFrame = V110_OnMatrix_9600;
		v->OfflineFrame = V110_OffMatrix_9600;
		break;
	}
	v->framelen = v->nbytes * 10;
	v->SyncInit = 5;
	v->introducer = 0;
	v->dbit = 1;
	v->b = 0;
	v->skbres = hdrlen;
	v->maxsize = maxsize - hdrlen;
	if ((v->encodebuf = kmalloc(maxsize, GFP_ATOMIC)) == NULL) {
		kfree(v);
		return NULL;
	}
	return v;
}

/* isdn_v110_close frees private V.110 data structures */
void
isdn_v110_close(isdn_v110_stream *v)
{
	if (v == NULL)
		return;
#ifdef ISDN_V110_DEBUG
	printk(KERN_DEBUG "v110 close\n");
#endif
	kfree(v->encodebuf);
	kfree(v);
}


/*
 * ValidHeaderBytes return the number of valid bytes in v->decodebuf
 */
static int
ValidHeaderBytes(isdn_v110_stream *v)
{
	int i;
	for (i = 0; (i < v->decodelen) && (i < v->nbytes); i++)
		if ((v->decodebuf[i] & v->key) != 0)
			break;
	return i;
}

/*
 * SyncHeader moves the decodebuf ptr to the next valid header
 */
static void
SyncHeader(isdn_v110_stream *v)
{
	unsigned char *rbuf = v->decodebuf;
	int len = v->decodelen;

	if (len == 0)
		return;
	for (rbuf++, len--; len > 0; len--, rbuf++)	/* such den SyncHeader in buf ! */
		if ((*rbuf & v->key) == 0)	/* erstes byte gefunden ?       */
			break;  /* jupp!                        */
	if (len)
		memcpy(v->decodebuf, rbuf, len);

	v->decodelen = len;
#ifdef ISDN_V110_DEBUG
	printk(KERN_DEBUG "isdn_v110: Header resync\n");
#endif
}

/* DecodeMatrix takes n (n>=1) matrices (v110 frames, 10 bytes) where
   len is the number of matrix-lines. len must be a multiple of 10, i.e.
   only complete matices must be given.
   From these, netto data is extracted and returned in buf. The return-value
   is the bytecount of the decoded data.
*/
static int
DecodeMatrix(isdn_v110_stream *v, unsigned char *m, int len, unsigned char *buf)
{
	int line = 0;
	int buflen = 0;
	int mbit = 64;
	int introducer = v->introducer;
	int dbit = v->dbit;
	unsigned char b = v->b;

	while (line < len) {    /* Are we done with all lines of the matrix? */
		if ((line % 10) == 0) {	/* the 0. line of the matrix is always 0 ! */
			if (m[line] != 0x00) {	/* not 0 ? -> error! */
#ifdef ISDN_V110_DEBUG
				printk(KERN_DEBUG "isdn_v110: DecodeMatrix, V110 Bad Header\n");
				/* returning now is not the right thing, though :-( */
#endif
			}
			line++; /* next line of matrix */
			continue;
		} else if ((line % 10) == 5) {	/* in line 5 there's only e-bits ! */
			if ((m[line] & 0x70) != 0x30) {	/* 011 has to be at the beginning! */
#ifdef ISDN_V110_DEBUG
				printk(KERN_DEBUG "isdn_v110: DecodeMatrix, V110 Bad 5th line\n");
				/* returning now is not the right thing, though :-( */
#endif
			}
			line++; /* next line */
			continue;
		} else if (!introducer) {	/* every byte starts with 10 (stopbit, startbit) */
			introducer = (m[line] & mbit) ? 0 : 1;	/* current bit of the matrix */
		next_byte:
			if (mbit > 2) {	/* was it the last bit in this line ? */
				mbit >>= 1;	/* no -> take next */
				continue;
			}       /* otherwise start with leftmost bit in the next line */
			mbit = 64;
			line++;
			continue;
		} else {        /* otherwise we need to set a data bit */
			if (m[line] & mbit)	/* was that bit set in the matrix ? */
				b |= dbit;	/* yes -> set it in the data byte */
			else
				b &= dbit - 1;	/* no -> clear it in the data byte */
			if (dbit < 128)	/* is that data byte done ? */
				dbit <<= 1;	/* no, got the next bit */
			else {  /* data byte is done */
				buf[buflen++] = b;	/* copy byte into the output buffer */
				introducer = b = 0;	/* init of the intro sequence and of the data byte */
				dbit = 1;	/* next we look for the 0th bit */
			}
			goto next_byte;	/* look for next bit in the matrix */
		}
	}
	v->introducer = introducer;
	v->dbit = dbit;
	v->b = b;
	return buflen;          /* return number of bytes in the output buffer */
}

/*
 * DecodeStream receives V.110 coded data from the input stream. It recovers the
 * original frames.
 * The input stream doesn't need to be framed
 */
struct sk_buff *
isdn_v110_decode(isdn_v110_stream *v, struct sk_buff *skb)
{
	int i;
	int j;
	int len;
	unsigned char *v110_buf;
	unsigned char *rbuf;

	if (!skb) {
		printk(KERN_WARNING "isdn_v110_decode called with NULL skb!\n");
		return NULL;
	}
	rbuf = skb->data;
	len = skb->len;
	if (v == NULL) {
		/* invalid handle, no chance to proceed */
		printk(KERN_WARNING "isdn_v110_decode called with NULL stream!\n");
		dev_kfree_skb(skb);
		return NULL;
	}
	if (v->decodelen == 0)  /* cache empty?               */
		for (; len > 0; len--, rbuf++)	/* scan for SyncHeader in buf */
			if ((*rbuf & v->key) == 0)
				break;	/* found first byte           */
	if (len == 0) {
		dev_kfree_skb(skb);
		return NULL;
	}
	/* copy new data to decode-buffer */
	memcpy(&(v->decodebuf[v->decodelen]), rbuf, len);
	v->decodelen += len;
ReSync:
	if (v->decodelen < v->nbytes) {	/* got a new header ? */
		dev_kfree_skb(skb);
		return NULL;    /* no, try later      */
	}
	if (ValidHeaderBytes(v) != v->nbytes) {	/* is that a valid header? */
		SyncHeader(v);  /* no -> look for header */
		goto ReSync;
	}
	len = (v->decodelen - (v->decodelen % (10 * v->nbytes))) / v->nbytes;
	if ((v110_buf = kmalloc(len, GFP_ATOMIC)) == NULL) {
		printk(KERN_WARNING "isdn_v110_decode: Couldn't allocate v110_buf\n");
		dev_kfree_skb(skb);
		return NULL;
	}
	for (i = 0; i < len; i++) {
		v110_buf[i] = 0;
		for (j = 0; j < v->nbytes; j++)
			v110_buf[i] |= (v->decodebuf[(i * v->nbytes) + j] & v->key) << (8 - ((j + 1) * v->nbits));
		v110_buf[i] = FlipBits(v110_buf[i], v->nbits);
	}
	v->decodelen = (v->decodelen % (10 * v->nbytes));
	memcpy(v->decodebuf, &(v->decodebuf[len * v->nbytes]), v->decodelen);

	skb_trim(skb, DecodeMatrix(v, v110_buf, len, skb->data));
	kfree(v110_buf);
	if (skb->len)
		return skb;
	else {
		kfree_skb(skb);
		return NULL;
	}
}

/* EncodeMatrix takes input data in buf, len is the bytecount.
   Data is encoded into v110 frames in m. Return value is the number of
   matrix-lines generated.
*/
static int
EncodeMatrix(unsigned char *buf, int len, unsigned char *m, int mlen)
{
	int line = 0;
	int i = 0;
	int mbit = 128;
	int dbit = 1;
	int introducer = 3;
	int ibit[] = {0, 1, 1};

	while ((i < len) && (line < mlen)) {	/* while we still have input data */
		switch (line % 10) {	/* in which line of the matrix are we? */
		case 0:
			m[line++] = 0x00;	/* line 0 is always 0 */
			mbit = 128;	/* go on with the 7th bit */
			break;
		case 5:
			m[line++] = 0xbf;	/* line 5 is always 10111111 */
			mbit = 128;	/* go on with the 7th bit */
			break;
		}
		if (line >= mlen) {
			printk(KERN_WARNING "isdn_v110 (EncodeMatrix): buffer full!\n");
			return line;
		}
	next_bit:
		switch (mbit) { /* leftmost or rightmost bit ? */
		case 1:
			line++;	/* rightmost -> go to next line */
			if (line >= mlen) {
				printk(KERN_WARNING "isdn_v110 (EncodeMatrix): buffer full!\n");
				return line;
			}
		case 128:
			m[line] = 128;	/* leftmost -> set byte to 1000000 */
			mbit = 64;	/* current bit in the matrix line */
			continue;
		}
		if (introducer) {	/* set 110 sequence ? */
			introducer--;	/* set on digit less */
			m[line] |= ibit[introducer] ? mbit : 0;	/* set corresponding bit */
			mbit >>= 1;	/* bit of matrix line  >> 1 */
			goto next_bit;	/* and go on there */
		}               /* else push data bits into the matrix! */
		m[line] |= (buf[i] & dbit) ? mbit : 0;	/* set data bit in matrix */
		if (dbit == 128) {	/* was it the last one? */
			dbit = 1;	/* then go on with first bit of  */
			i++;            /* next byte in input buffer */
			if (i < len)	/* input buffer done ? */
				introducer = 3;	/* no, write introducer 110 */
			else {  /* input buffer done ! */
				m[line] |= (mbit - 1) & 0xfe;	/* set remaining bits in line to 1 */
				break;
			}
		} else          /* not the last data bit */
			dbit <<= 1;	/* then go to next data bit */
		mbit >>= 1;     /* go to next bit of matrix */
		goto next_bit;

	}
	/* if necessary, generate remaining lines of the matrix... */
	if ((line) && ((line + 10) < mlen))
		switch (++line % 10) {
		case 1:
			m[line++] = 0xfe;
		case 2:
			m[line++] = 0xfe;
		case 3:
			m[line++] = 0xfe;
		case 4:
			m[line++] = 0xfe;
		case 5:
			m[line++] = 0xbf;
		case 6:
			m[line++] = 0xfe;
		case 7:
			m[line++] = 0xfe;
		case 8:
			m[line++] = 0xfe;
		case 9:
			m[line++] = 0xfe;
		}
	return line;            /* that's how many lines we have */
}

/*
 * Build a sync frame.
 */
static struct sk_buff *
isdn_v110_sync(isdn_v110_stream *v)
{
	struct sk_buff *skb;

	if (v == NULL) {
		/* invalid handle, no chance to proceed */
		printk(KERN_WARNING "isdn_v110_sync called with NULL stream!\n");
		return NULL;
	}
	if ((skb = dev_alloc_skb(v->framelen + v->skbres))) {
		skb_reserve(skb, v->skbres);
		skb_put_data(skb, v->OfflineFrame, v->framelen);
	}
	return skb;
}

/*
 * Build an idle frame.
 */
static struct sk_buff *
isdn_v110_idle(isdn_v110_stream *v)
{
	struct sk_buff *skb;

	if (v == NULL) {
		/* invalid handle, no chance to proceed */
		printk(KERN_WARNING "isdn_v110_sync called with NULL stream!\n");
		return NULL;
	}
	if ((skb = dev_alloc_skb(v->framelen + v->skbres))) {
		skb_reserve(skb, v->skbres);
		skb_put_data(skb, v->OnlineFrame, v->framelen);
	}
	return skb;
}

struct sk_buff *
isdn_v110_encode(isdn_v110_stream *v, struct sk_buff *skb)
{
	int i;
	int j;
	int rlen;
	int mlen;
	int olen;
	int size;
	int sval1;
	int sval2;
	int nframes;
	unsigned char *v110buf;
	unsigned char *rbuf;
	struct sk_buff *nskb;

	if (v == NULL) {
		/* invalid handle, no chance to proceed */
		printk(KERN_WARNING "isdn_v110_encode called with NULL stream!\n");
		return NULL;
	}
	if (!skb) {
		/* invalid skb, no chance to proceed */
		printk(KERN_WARNING "isdn_v110_encode called with NULL skb!\n");
		return NULL;
	}
	rlen = skb->len;
	nframes = (rlen + 3) / 4;
	v110buf = v->encodebuf;
	if ((nframes * 40) > v->maxsize) {
		size = v->maxsize;
		rlen = v->maxsize / 40;
	} else
		size = nframes * 40;
	if (!(nskb = dev_alloc_skb(size + v->skbres + sizeof(int)))) {
		printk(KERN_WARNING "isdn_v110_encode: Couldn't alloc skb\n");
		return NULL;
	}
	skb_reserve(nskb, v->skbres + sizeof(int));
	if (skb->len == 0) {
		skb_put_data(nskb, v->OnlineFrame, v->framelen);
		*((int *)skb_push(nskb, sizeof(int))) = 0;
		return nskb;
	}
	mlen = EncodeMatrix(skb->data, rlen, v110buf, size);
	/* now distribute 2 or 4 bits each to the output stream! */
	rbuf = skb_put(nskb, size);
	olen = 0;
	sval1 = 8 - v->nbits;
	sval2 = v->key << sval1;
	for (i = 0; i < mlen; i++) {
		v110buf[i] = FlipBits(v110buf[i], v->nbits);
		for (j = 0; j < v->nbytes; j++) {
			if (size--)
				*rbuf++ = ~v->key | (((v110buf[i] << (j * v->nbits)) & sval2) >> sval1);
			else {
				printk(KERN_WARNING "isdn_v110_encode: buffers full!\n");
				goto buffer_full;
			}
			olen++;
		}
	}
buffer_full:
	skb_trim(nskb, olen);
	*((int *)skb_push(nskb, sizeof(int))) = rlen;
	return nskb;
}

int
isdn_v110_stat_callback(int idx, isdn_ctrl *c)
{
	isdn_v110_stream *v = NULL;
	int i;
	int ret = 0;

	if (idx < 0)
		return 0;
	switch (c->command) {
	case ISDN_STAT_BSENT:
		/* Keep the send-queue of the driver filled
		 * with frames:
		 * If number of outstanding frames < 3,
		 * send down an Idle-Frame (or an Sync-Frame, if
		 * v->SyncInit != 0).
		 */
		if (!(v = dev->v110[idx]))
			return 0;
		atomic_inc(&dev->v110use[idx]);
		for (i = 0; i * v->framelen < c->parm.length; i++) {
			if (v->skbidle > 0) {
				v->skbidle--;
				ret = 1;
			} else {
				if (v->skbuser > 0)
					v->skbuser--;
				ret = 0;
			}
		}
		for (i = v->skbuser + v->skbidle; i < 2; i++) {
			struct sk_buff *skb;
			if (v->SyncInit > 0)
				skb = isdn_v110_sync(v);
			else
				skb = isdn_v110_idle(v);
			if (skb) {
				if (dev->drv[c->driver]->interface->writebuf_skb(c->driver, c->arg, 1, skb) <= 0) {
					dev_kfree_skb(skb);
					break;
				} else {
					if (v->SyncInit)
						v->SyncInit--;
					v->skbidle++;
				}
			} else
				break;
		}
		atomic_dec(&dev->v110use[idx]);
		return ret;
	case ISDN_STAT_DHUP:
	case ISDN_STAT_BHUP:
		while (1) {
			atomic_inc(&dev->v110use[idx]);
			if (atomic_dec_and_test(&dev->v110use[idx])) {
				isdn_v110_close(dev->v110[idx]);
				dev->v110[idx] = NULL;
				break;
			}
			mdelay(1);
		}
		break;
	case ISDN_STAT_BCONN:
		if (dev->v110emu[idx] && (dev->v110[idx] == NULL)) {
			int hdrlen = dev->drv[c->driver]->interface->hl_hdrlen;
			int maxsize = dev->drv[c->driver]->interface->maxbufsize;
			atomic_inc(&dev->v110use[idx]);
			switch (dev->v110emu[idx]) {
			case ISDN_PROTO_L2_V11096:
				dev->v110[idx] = isdn_v110_open(V110_9600, hdrlen, maxsize);
				break;
			case ISDN_PROTO_L2_V11019:
				dev->v110[idx] = isdn_v110_open(V110_19200, hdrlen, maxsize);
				break;
			case ISDN_PROTO_L2_V11038:
				dev->v110[idx] = isdn_v110_open(V110_38400, hdrlen, maxsize);
				break;
			default:;
			}
			if ((v = dev->v110[idx])) {
				while (v->SyncInit) {
					struct sk_buff *skb = isdn_v110_sync(v);
					if (dev->drv[c->driver]->interface->writebuf_skb(c->driver, c->arg, 1, skb) <= 0) {
						dev_kfree_skb(skb);
						/* Unable to send, try later */
						break;
					}
					v->SyncInit--;
					v->skbidle++;
				}
			} else
				printk(KERN_WARNING "isdn_v110: Couldn't open stream for chan %d\n", idx);
			atomic_dec(&dev->v110use[idx]);
		}
		break;
	default:
		return 0;
	}
	return 0;
}