aboutsummaryrefslogtreecommitdiff
path: root/drivers/isdn/pcbit/layer2.c
blob: 58eee50c8e263debb3a2848e71f778bb09f8ef86 (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
/*
 * PCBIT-D low-layer interface
 *
 * Copyright (C) 1996 Universidade de Lisboa
 *
 * Written by Pedro Roque Marques (roque@di.fc.ul.pt)
 *
 * This software may be used and distributed according to the terms of
 * the GNU General Public License, incorporated herein by reference.
 */

/*
 * 19991203 - Fernando Carvalho - takion@superbofh.org
 * Hacked to compile with egcs and run with current version of isdn modules
*/

/*
 *        Based on documentation provided by Inesc:
 *        - "Interface com bus do PC para o PCBIT e PCBIT-D", Inesc, Jan 93
 */

/*
 *        TODO: better handling of errors
 *              re-write/remove debug printks
 */

#include <linux/sched.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/mm.h>
#include <linux/skbuff.h>

#include <linux/isdnif.h>

#include <asm/system.h>
#include <asm/io.h>


#include "pcbit.h"
#include "layer2.h"
#include "edss1.h"

#undef DEBUG_FRAG


/*
 *  Prototypes
 */

static void pcbit_transmit(struct pcbit_dev *dev);

static void pcbit_recv_ack(struct pcbit_dev *dev, unsigned char ack);

static void pcbit_l2_error(struct pcbit_dev *dev);
static void pcbit_l2_active_conf(struct pcbit_dev *dev, u_char info);
static void pcbit_l2_err_recover(unsigned long data);

static void pcbit_firmware_bug(struct pcbit_dev *dev);

static __inline__ void
pcbit_sched_delivery(struct pcbit_dev *dev)
{
	schedule_work(&dev->qdelivery);
}


/*
 *  Called from layer3
 */

int
pcbit_l2_write(struct pcbit_dev *dev, ulong msg, ushort refnum,
	       struct sk_buff *skb, unsigned short hdr_len)
{
	struct frame_buf *frame,
	*ptr;
	unsigned long flags;

	if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING) {
		dev_kfree_skb(skb);
		return -1;
	}
	if ((frame = kmalloc(sizeof(struct frame_buf),
						  GFP_ATOMIC)) == NULL) {
		printk(KERN_WARNING "pcbit_2_write: kmalloc failed\n");
		dev_kfree_skb(skb);
		return -1;
	}
	frame->msg = msg;
	frame->refnum = refnum;
	frame->copied = 0;
	frame->hdr_len = hdr_len;

	if (skb)
		frame->dt_len = skb->len - hdr_len;
	else
		frame->dt_len = 0;

	frame->skb = skb;

	frame->next = NULL;

	spin_lock_irqsave(&dev->lock, flags);

	if (dev->write_queue == NULL) {
		dev->write_queue = frame;
		spin_unlock_irqrestore(&dev->lock, flags);
		pcbit_transmit(dev);
	} else {
		for (ptr = dev->write_queue; ptr->next; ptr = ptr->next);
		ptr->next = frame;

		spin_unlock_irqrestore(&dev->lock, flags);
	}
	return 0;
}

static __inline__ void
pcbit_tx_update(struct pcbit_dev *dev, ushort len)
{
	u_char info;

	dev->send_seq = (dev->send_seq + 1) % 8;

	dev->fsize[dev->send_seq] = len;
	info = 0;
	info |= dev->rcv_seq << 3;
	info |= dev->send_seq;

	writeb(info, dev->sh_mem + BANK4);

}

/*
 * called by interrupt service routine or by write_2
 */

static void
pcbit_transmit(struct pcbit_dev *dev)
{
	struct frame_buf *frame = NULL;
	unsigned char unacked;
	int flen;               /* fragment frame length including all headers */
	int free;
	int count,
	 cp_len;
	unsigned long flags;
	unsigned short tt;

	if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING)
		return;

	unacked = (dev->send_seq + (8 - dev->unack_seq)) & 0x07;

	spin_lock_irqsave(&dev->lock, flags);

	if (dev->free > 16 && dev->write_queue && unacked < 7) {

		if (!dev->w_busy)
			dev->w_busy = 1;
		else {
			spin_unlock_irqrestore(&dev->lock, flags);
			return;
		}


		frame = dev->write_queue;
		free = dev->free;

		spin_unlock_irqrestore(&dev->lock, flags);

		if (frame->copied == 0) {

			/* Type 0 frame */

			ulong 	msg;

			if (frame->skb)
				flen = FRAME_HDR_LEN + PREHDR_LEN + frame->skb->len;
			else
				flen = FRAME_HDR_LEN + PREHDR_LEN;

			if (flen > free)
				flen = free;

			msg = frame->msg;

			/*
			 *  Board level 2 header
			 */

			pcbit_writew(dev, flen - FRAME_HDR_LEN);

			pcbit_writeb(dev, GET_MSG_CPU(msg));

			pcbit_writeb(dev, GET_MSG_PROC(msg));

			/* TH */
			pcbit_writew(dev, frame->hdr_len + PREHDR_LEN);

			/* TD */
			pcbit_writew(dev, frame->dt_len);


			/*
			 *  Board level 3 fixed-header
			 */

			/* LEN = TH */
			pcbit_writew(dev, frame->hdr_len + PREHDR_LEN);

			/* XX */
			pcbit_writew(dev, 0);

			/* C + S */
			pcbit_writeb(dev, GET_MSG_CMD(msg));
			pcbit_writeb(dev, GET_MSG_SCMD(msg));

			/* NUM */
			pcbit_writew(dev, frame->refnum);

			count = FRAME_HDR_LEN + PREHDR_LEN;
		} else {
			/* Type 1 frame */

			flen = 2 + (frame->skb->len - frame->copied);

			if (flen > free)
				flen = free;

			/* TT */
			tt = ((ushort) (flen - 2)) | 0x8000U;	/* Type 1 */
			pcbit_writew(dev, tt);

			count = 2;
		}

		if (frame->skb) {
			cp_len = frame->skb->len - frame->copied;
			if (cp_len > flen - count)
				cp_len = flen - count;

			memcpy_topcbit(dev, frame->skb->data + frame->copied,
				       cp_len);
			frame->copied += cp_len;
		}
		/* bookkeeping */
		dev->free -= flen;
		pcbit_tx_update(dev, flen);

		spin_lock_irqsave(&dev->lock, flags);

		if (frame->skb == NULL || frame->copied == frame->skb->len) {

			dev->write_queue = frame->next;

			if (frame->skb != NULL) {
				/* free frame */
				dev_kfree_skb(frame->skb);
			}
			kfree(frame);
		}
		dev->w_busy = 0;
		spin_unlock_irqrestore(&dev->lock, flags);
	} else {
		spin_unlock_irqrestore(&dev->lock, flags);
#ifdef DEBUG
		printk(KERN_DEBUG "unacked %d free %d write_queue %s\n",
		     unacked, dev->free, dev->write_queue ? "not empty" :
		       "empty");
#endif
	}
}


/*
 *  deliver a queued frame to the upper layer
 */

void
pcbit_deliver(struct work_struct *work)
{
	struct frame_buf *frame;
	unsigned long flags, msg;
	struct pcbit_dev *dev =
		container_of(work, struct pcbit_dev, qdelivery);

	spin_lock_irqsave(&dev->lock, flags);

	while ((frame = dev->read_queue)) {
		dev->read_queue = frame->next;
		spin_unlock_irqrestore(&dev->lock, flags);

		msg = 0;
		SET_MSG_CPU(msg, 0);
		SET_MSG_PROC(msg, 0);
		SET_MSG_CMD(msg, frame->skb->data[2]);
		SET_MSG_SCMD(msg, frame->skb->data[3]);

		frame->refnum = *((ushort *) frame->skb->data + 4);
		frame->msg = *((ulong *) & msg);

		skb_pull(frame->skb, 6);

		pcbit_l3_receive(dev, frame->msg, frame->skb, frame->hdr_len,
				 frame->refnum);

		kfree(frame);

		spin_lock_irqsave(&dev->lock, flags);
	}

	spin_unlock_irqrestore(&dev->lock, flags);
}

/*
 * Reads BANK 2 & Reassembles
 */

static void
pcbit_receive(struct pcbit_dev *dev)
{
	unsigned short tt;
	u_char cpu,
	 proc;
	struct frame_buf *frame = NULL;
	unsigned long flags;
	u_char type1;

	if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING)
		return;

	tt = pcbit_readw(dev);

	if ((tt & 0x7fffU) > 511) {
		printk(KERN_INFO "pcbit: invalid frame length -> TT=%04x\n",
		       tt);
		pcbit_l2_error(dev);
		return;
	}
	if (!(tt & 0x8000U)) {  /* Type 0 */
		type1 = 0;

		if (dev->read_frame) {
			printk(KERN_DEBUG "pcbit_receive: Type 0 frame and read_frame != NULL\n");
			/* discard previous queued frame */
			if (dev->read_frame->skb)
				kfree_skb(dev->read_frame->skb);
			kfree(dev->read_frame);
			dev->read_frame = NULL;
		}
		frame = kzalloc(sizeof(struct frame_buf), GFP_ATOMIC);

		if (frame == NULL) {
			printk(KERN_WARNING "kmalloc failed\n");
			return;
		}

		cpu = pcbit_readb(dev);
		proc = pcbit_readb(dev);


		if (cpu != 0x06 && cpu != 0x02) {
			printk(KERN_DEBUG "pcbit: invalid cpu value\n");
			kfree(frame);
			pcbit_l2_error(dev);
			return;
		}
		/*
		 * we discard cpu & proc on receiving
		 * but we read it to update the pointer
		 */

		frame->hdr_len = pcbit_readw(dev);
		frame->dt_len = pcbit_readw(dev);

		/*
		   * 0 sized packet
		   * I don't know if they are an error or not...
		   * But they are very frequent
		   * Not documented
		 */

		if (frame->hdr_len == 0) {
			kfree(frame);
#ifdef DEBUG
			printk(KERN_DEBUG "0 sized frame\n");
#endif
			pcbit_firmware_bug(dev);
			return;
		}
		/* sanity check the length values */
		if (frame->hdr_len > 1024 || frame->dt_len > 2048) {
#ifdef DEBUG
			printk(KERN_DEBUG "length problem: ");
			printk(KERN_DEBUG "TH=%04x TD=%04x\n",
			       frame->hdr_len,
			       frame->dt_len);
#endif
			pcbit_l2_error(dev);
			kfree(frame);
			return;
		}
		/* minimum frame read */

		frame->skb = dev_alloc_skb(frame->hdr_len + frame->dt_len +
					   ((frame->hdr_len + 15) & ~15));

		if (!frame->skb) {
			printk(KERN_DEBUG "pcbit_receive: out of memory\n");
			kfree(frame);
			return;
		}
		/* 16 byte alignment for IP */
		if (frame->dt_len)
			skb_reserve(frame->skb, (frame->hdr_len + 15) & ~15);

	} else {
		/* Type 1 */
		type1 = 1;
		tt &= 0x7fffU;

		if (!(frame = dev->read_frame)) {
			printk("Type 1 frame and no frame queued\n");
			/* usually after an error: toss frame */
			dev->readptr += tt;
			if (dev->readptr > dev->sh_mem + BANK2 + BANKLEN)
				dev->readptr -= BANKLEN;
			return;

		}
	}

	memcpy_frompcbit(dev, skb_put(frame->skb, tt), tt);

	frame->copied += tt;
	spin_lock_irqsave(&dev->lock, flags);
	if (frame->copied == frame->hdr_len + frame->dt_len) {

		if (type1) {
			dev->read_frame = NULL;
		}
		if (dev->read_queue) {
			struct frame_buf *ptr;
			for (ptr = dev->read_queue; ptr->next; ptr = ptr->next);
			ptr->next = frame;
		} else
			dev->read_queue = frame;

	} else {
		dev->read_frame = frame;
	}
	spin_unlock_irqrestore(&dev->lock, flags);
}

/*
 *  The board sends 0 sized frames
 *  They are TDATA_CONFs that get messed up somehow
 *  gotta send a fake acknowledgment to the upper layer somehow
 */

static __inline__ void
pcbit_fake_conf(struct pcbit_dev *dev, struct pcbit_chan *chan)
{
	isdn_ctrl ictl;

	if (chan->queued) {
		chan->queued--;

		ictl.driver = dev->id;
		ictl.command = ISDN_STAT_BSENT;
		ictl.arg = chan->id;
		dev->dev_if->statcallb(&ictl);
	}
}

static void
pcbit_firmware_bug(struct pcbit_dev *dev)
{
	struct pcbit_chan *chan;

	chan = dev->b1;

	if (chan->fsm_state == ST_ACTIVE) {
		pcbit_fake_conf(dev, chan);
	}
	chan = dev->b2;

	if (chan->fsm_state == ST_ACTIVE) {
		pcbit_fake_conf(dev, chan);
	}
}

irqreturn_t
pcbit_irq_handler(int interrupt, void *devptr)
{
	struct pcbit_dev *dev;
	u_char info,
	 ack_seq,
	 read_seq;

	dev = (struct pcbit_dev *) devptr;

	if (!dev) {
		printk(KERN_WARNING "pcbit_irq_handler: wrong device\n");
		return IRQ_NONE;
	}
	if (dev->interrupt) {
		printk(KERN_DEBUG "pcbit: reentering interrupt hander\n");
		return IRQ_HANDLED;
	}
	dev->interrupt = 1;

	info = readb(dev->sh_mem + BANK3);

	if (dev->l2_state == L2_STARTING || dev->l2_state == L2_ERROR) {
		pcbit_l2_active_conf(dev, info);
		dev->interrupt = 0;
		return IRQ_HANDLED;
	}
	if (info & 0x40U) {     /* E bit set */
#ifdef DEBUG
		printk(KERN_DEBUG "pcbit_irq_handler: E bit on\n");
#endif
		pcbit_l2_error(dev);
		dev->interrupt = 0;
		return IRQ_HANDLED;
	}
	if (dev->l2_state != L2_RUNNING && dev->l2_state != L2_LOADING) {
		dev->interrupt = 0;
		return IRQ_HANDLED;
	}
	ack_seq = (info >> 3) & 0x07U;
	read_seq = (info & 0x07U);

	dev->interrupt = 0;

	if (read_seq != dev->rcv_seq) {
		while (read_seq != dev->rcv_seq) {
			pcbit_receive(dev);
			dev->rcv_seq = (dev->rcv_seq + 1) % 8;
		}
		pcbit_sched_delivery(dev);
	}
	if (ack_seq != dev->unack_seq) {
		pcbit_recv_ack(dev, ack_seq);
	}
	info = dev->rcv_seq << 3;
	info |= dev->send_seq;

	writeb(info, dev->sh_mem + BANK4);
	return IRQ_HANDLED;
}


static void
pcbit_l2_active_conf(struct pcbit_dev *dev, u_char info)
{
	u_char state;

	state = dev->l2_state;

#ifdef DEBUG
	printk(KERN_DEBUG "layer2_active_confirm\n");
#endif


	if (info & 0x80U) {
		dev->rcv_seq = info & 0x07U;
		dev->l2_state = L2_RUNNING;
	} else
		dev->l2_state = L2_DOWN;

	if (state == L2_STARTING)
		wake_up_interruptible(&dev->set_running_wq);

	if (state == L2_ERROR && dev->l2_state == L2_RUNNING) {
		pcbit_transmit(dev);
	}
}

static void
pcbit_l2_err_recover(unsigned long data)
{

	struct pcbit_dev *dev;
	struct frame_buf *frame;

	dev = (struct pcbit_dev *) data;

	del_timer(&dev->error_recover_timer);
	if (dev->w_busy || dev->r_busy) {
		init_timer(&dev->error_recover_timer);
		dev->error_recover_timer.expires = jiffies + ERRTIME;
		add_timer(&dev->error_recover_timer);
		return;
	}
	dev->w_busy = dev->r_busy = 1;

	if (dev->read_frame) {
		if (dev->read_frame->skb)
			kfree_skb(dev->read_frame->skb);
		kfree(dev->read_frame);
		dev->read_frame = NULL;
	}
	if (dev->write_queue) {
		frame = dev->write_queue;
#ifdef FREE_ON_ERROR
		dev->write_queue = dev->write_queue->next;

		if (frame->skb) {
			dev_kfree_skb(frame->skb);
		}
		kfree(frame);
#else
		frame->copied = 0;
#endif
	}
	dev->rcv_seq = dev->send_seq = dev->unack_seq = 0;
	dev->free = 511;
	dev->l2_state = L2_ERROR;

	/* this is an hack... */
	pcbit_firmware_bug(dev);

	dev->writeptr = dev->sh_mem;
	dev->readptr = dev->sh_mem + BANK2;

	writeb((0x80U | ((dev->rcv_seq & 0x07) << 3) | (dev->send_seq & 0x07)),
	       dev->sh_mem + BANK4);
	dev->w_busy = dev->r_busy = 0;

}

static void
pcbit_l2_error(struct pcbit_dev *dev)
{
	if (dev->l2_state == L2_RUNNING) {

		printk(KERN_INFO "pcbit: layer 2 error\n");

#ifdef DEBUG
		log_state(dev);
#endif

		dev->l2_state = L2_DOWN;

		init_timer(&dev->error_recover_timer);
		dev->error_recover_timer.function = &pcbit_l2_err_recover;
		dev->error_recover_timer.data = (ulong) dev;
		dev->error_recover_timer.expires = jiffies + ERRTIME;
		add_timer(&dev->error_recover_timer);
	}
}

/*
 * Description:
 * if board acks frames
 *   update dev->free
 *   call pcbit_transmit to write possible queued frames
 */

static void
pcbit_recv_ack(struct pcbit_dev *dev, unsigned char ack)
{
	int i,
	 count;
	int unacked;

	unacked = (dev->send_seq + (8 - dev->unack_seq)) & 0x07;

	/* dev->unack_seq < ack <= dev->send_seq; */

	if (unacked) {

		if (dev->send_seq > dev->unack_seq) {
			if (ack <= dev->unack_seq || ack > dev->send_seq) {
				printk(KERN_DEBUG
				     "layer 2 ack unacceptable - dev %d",
				       dev->id);

				pcbit_l2_error(dev);
			} else if (ack > dev->send_seq && ack <= dev->unack_seq) {
				printk(KERN_DEBUG
				     "layer 2 ack unacceptable - dev %d",
				       dev->id);
				pcbit_l2_error(dev);
			}
		}
		/* ack is acceptable */


		i = dev->unack_seq;

		do {
			dev->unack_seq = i = (i + 1) % 8;
			dev->free += dev->fsize[i];
		} while (i != ack);

		count = 0;
		while (count < 7 && dev->write_queue) {
			u8 lsend_seq = dev->send_seq;

			pcbit_transmit(dev);

			if (dev->send_seq == lsend_seq)
				break;
			count++;
		}
	} else
		printk(KERN_DEBUG "recv_ack: unacked = 0\n");
}