summaryrefslogtreecommitdiff
path: root/drivers/misc/ti-st/st_core.c
blob: c8c6a363069cc189b799bcf376fcf6991cc05e6e (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
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
/*
 *  Shared Transport Line discipline driver Core
 *	This hooks up ST KIM driver and ST LL driver
 *  Copyright (C) 2009-2010 Texas Instruments
 *  Author: Pavan Savoy <pavan_savoy@ti.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#define pr_fmt(fmt)	"(stc): " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/tty.h>

#include <linux/seq_file.h>
#include <linux/skbuff.h>

#include <linux/ti_wilink_st.h>

extern void st_kim_recv(void *, const unsigned char *, long);
void st_int_recv(void *, const unsigned char *, long);
/* function pointer pointing to either,
 * st_kim_recv during registration to receive fw download responses
 * st_int_recv after registration to receive proto stack responses
 */
static void (*st_recv) (void *, const unsigned char *, long);

/********************************************************************/
static void add_channel_to_table(struct st_data_s *st_gdata,
		struct st_proto_s *new_proto)
{
	pr_info("%s: id %d\n", __func__, new_proto->chnl_id);
	/* list now has the channel id as index itself */
	st_gdata->list[new_proto->chnl_id] = new_proto;
	st_gdata->is_registered[new_proto->chnl_id] = true;
}

static void remove_channel_from_table(struct st_data_s *st_gdata,
		struct st_proto_s *proto)
{
	pr_info("%s: id %d\n", __func__, proto->chnl_id);
/*	st_gdata->list[proto->chnl_id] = NULL; */
	st_gdata->is_registered[proto->chnl_id] = false;
}

/*
 * called from KIM during firmware download.
 *
 * This is a wrapper function to tty->ops->write_room.
 * It returns number of free space available in
 * uart tx buffer.
 */
int st_get_uart_wr_room(struct st_data_s *st_gdata)
{
	struct tty_struct *tty;
	if (unlikely(st_gdata == NULL || st_gdata->tty == NULL)) {
		pr_err("tty unavailable to perform write");
		return -1;
	}
	tty = st_gdata->tty;
	return tty->ops->write_room(tty);
}

/* can be called in from
 * -- KIM (during fw download)
 * -- ST Core (during st_write)
 *
 *  This is the internal write function - a wrapper
 *  to tty->ops->write
 */
int st_int_write(struct st_data_s *st_gdata,
	const unsigned char *data, int count)
{
	struct tty_struct *tty;
	if (unlikely(st_gdata == NULL || st_gdata->tty == NULL)) {
		pr_err("tty unavailable to perform write");
		return -EINVAL;
	}
	tty = st_gdata->tty;
#ifdef VERBOSE
	print_hex_dump(KERN_DEBUG, "<out<", DUMP_PREFIX_NONE,
		16, 1, data, count, 0);
#endif
	return tty->ops->write(tty, data, count);

}

/*
 * push the skb received to relevant
 * protocol stacks
 */
static void st_send_frame(unsigned char chnl_id, struct st_data_s *st_gdata)
{
	pr_debug(" %s(prot:%d) ", __func__, chnl_id);

	if (unlikely
	    (st_gdata == NULL || st_gdata->rx_skb == NULL
	     || st_gdata->is_registered[chnl_id] == false)) {
		pr_err("chnl_id %d not registered, no data to send?",
			   chnl_id);
		kfree_skb(st_gdata->rx_skb);
		return;
	}
	/* this cannot fail
	 * this shouldn't take long
	 * - should be just skb_queue_tail for the
	 *   protocol stack driver
	 */
	if (likely(st_gdata->list[chnl_id]->recv != NULL)) {
		if (unlikely
			(st_gdata->list[chnl_id]->recv
			(st_gdata->list[chnl_id]->priv_data, st_gdata->rx_skb)
			     != 0)) {
			pr_err(" proto stack %d's ->recv failed", chnl_id);
			kfree_skb(st_gdata->rx_skb);
			return;
		}
	} else {
		pr_err(" proto stack %d's ->recv null", chnl_id);
		kfree_skb(st_gdata->rx_skb);
	}
	return;
}

/**
 * st_reg_complete -
 * to call registration complete callbacks
 * of all protocol stack drivers
 * This function is being called with spin lock held, protocol drivers are
 * only expected to complete their waits and do nothing more than that.
 */
static void st_reg_complete(struct st_data_s *st_gdata, char err)
{
	unsigned char i = 0;
	pr_info(" %s ", __func__);
	for (i = 0; i < ST_MAX_CHANNELS; i++) {
		if (likely(st_gdata != NULL &&
			st_gdata->is_registered[i] == true &&
				st_gdata->list[i]->reg_complete_cb != NULL)) {
			st_gdata->list[i]->reg_complete_cb
				(st_gdata->list[i]->priv_data, err);
			pr_info("protocol %d's cb sent %d\n", i, err);
			if (err) { /* cleanup registered protocol */
				st_gdata->is_registered[i] = false;
				if (st_gdata->protos_registered)
					st_gdata->protos_registered--;
			}
		}
	}
}

static inline int st_check_data_len(struct st_data_s *st_gdata,
	unsigned char chnl_id, int len)
{
	int room = skb_tailroom(st_gdata->rx_skb);

	pr_debug("len %d room %d", len, room);

	if (!len) {
		/* Received packet has only packet header and
		 * has zero length payload. So, ask ST CORE to
		 * forward the packet to protocol driver (BT/FM/GPS)
		 */
		st_send_frame(chnl_id, st_gdata);

	} else if (len > room) {
		/* Received packet's payload length is larger.
		 * We can't accommodate it in created skb.
		 */
		pr_err("Data length is too large len %d room %d", len,
			   room);
		kfree_skb(st_gdata->rx_skb);
	} else {
		/* Packet header has non-zero payload length and
		 * we have enough space in created skb. Lets read
		 * payload data */
		st_gdata->rx_state = ST_W4_DATA;
		st_gdata->rx_count = len;
		return len;
	}

	/* Change ST state to continue to process next
	 * packet */
	st_gdata->rx_state = ST_W4_PACKET_TYPE;
	st_gdata->rx_skb = NULL;
	st_gdata->rx_count = 0;
	st_gdata->rx_chnl = 0;

	return 0;
}

/**
 * st_wakeup_ack - internal function for action when wake-up ack
 *	received
 */
static inline void st_wakeup_ack(struct st_data_s *st_gdata,
	unsigned char cmd)
{
	struct sk_buff *waiting_skb;
	unsigned long flags = 0;

	spin_lock_irqsave(&st_gdata->lock, flags);
	/* de-Q from waitQ and Q in txQ now that the
	 * chip is awake
	 */
	while ((waiting_skb = skb_dequeue(&st_gdata->tx_waitq)))
		skb_queue_tail(&st_gdata->txq, waiting_skb);

	/* state forwarded to ST LL */
	st_ll_sleep_state(st_gdata, (unsigned long)cmd);
	spin_unlock_irqrestore(&st_gdata->lock, flags);

	/* wake up to send the recently copied skbs from waitQ */
	st_tx_wakeup(st_gdata);
}

/**
 * st_int_recv - ST's internal receive function.
 *	Decodes received RAW data and forwards to corresponding
 *	client drivers (Bluetooth,FM,GPS..etc).
 *	This can receive various types of packets,
 *	HCI-Events, ACL, SCO, 4 types of HCI-LL PM packets
 *	CH-8 packets from FM, CH-9 packets from GPS cores.
 */
void st_int_recv(void *disc_data,
	const unsigned char *data, long count)
{
	char *ptr;
	struct st_proto_s *proto;
	unsigned short payload_len = 0;
	int len = 0;
	unsigned char type = 0;
	unsigned char *plen;
	struct st_data_s *st_gdata = (struct st_data_s *)disc_data;
	unsigned long flags;

	ptr = (char *)data;
	/* tty_receive sent null ? */
	if (unlikely(ptr == NULL) || (st_gdata == NULL)) {
		pr_err(" received null from TTY ");
		return;
	}

	pr_debug("count %ld rx_state %ld"
		   "rx_count %ld", count, st_gdata->rx_state,
		   st_gdata->rx_count);

	spin_lock_irqsave(&st_gdata->lock, flags);
	/* Decode received bytes here */
	while (count) {
		if (st_gdata->rx_count) {
			len = min_t(unsigned int, st_gdata->rx_count, count);
			memcpy(skb_put(st_gdata->rx_skb, len), ptr, len);
			st_gdata->rx_count -= len;
			count -= len;
			ptr += len;

			if (st_gdata->rx_count)
				continue;

			/* Check ST RX state machine , where are we? */
			switch (st_gdata->rx_state) {
			/* Waiting for complete packet ? */
			case ST_W4_DATA:
				pr_debug("Complete pkt received");
				/* Ask ST CORE to forward
				 * the packet to protocol driver */
				st_send_frame(st_gdata->rx_chnl, st_gdata);

				st_gdata->rx_state = ST_W4_PACKET_TYPE;
				st_gdata->rx_skb = NULL;
				continue;
			/* parse the header to know details */
			case ST_W4_HEADER:
				proto = st_gdata->list[st_gdata->rx_chnl];
				plen =
				&st_gdata->rx_skb->data
				[proto->offset_len_in_hdr];
				pr_debug("plen pointing to %x\n", *plen);
				if (proto->len_size == 1)/* 1 byte len field */
					payload_len = *(unsigned char *)plen;
				else if (proto->len_size == 2)
					payload_len =
					__le16_to_cpu(*(unsigned short *)plen);
				else
					pr_info("%s: invalid length "
					"for id %d\n",
					__func__, proto->chnl_id);
				st_check_data_len(st_gdata, proto->chnl_id,
						payload_len);
				pr_debug("off %d, pay len %d\n",
					proto->offset_len_in_hdr, payload_len);
				continue;
			}	/* end of switch rx_state */
		}

		/* end of if rx_count */
		/* Check first byte of packet and identify module
		 * owner (BT/FM/GPS) */
		switch (*ptr) {
		case LL_SLEEP_IND:
		case LL_SLEEP_ACK:
		case LL_WAKE_UP_IND:
			pr_debug("PM packet");
			/* this takes appropriate action based on
			 * sleep state received --
			 */
			st_ll_sleep_state(st_gdata, *ptr);
			/* if WAKEUP_IND collides copy from waitq to txq
			 * and assume chip awake
			 */
			spin_unlock_irqrestore(&st_gdata->lock, flags);
			if (st_ll_getstate(st_gdata) == ST_LL_AWAKE)
				st_wakeup_ack(st_gdata, LL_WAKE_UP_ACK);
			spin_lock_irqsave(&st_gdata->lock, flags);

			ptr++;
			count--;
			continue;
		case LL_WAKE_UP_ACK:
			pr_debug("PM packet");

			spin_unlock_irqrestore(&st_gdata->lock, flags);
			/* wake up ack received */
			st_wakeup_ack(st_gdata, *ptr);
			spin_lock_irqsave(&st_gdata->lock, flags);

			ptr++;
			count--;
			continue;
			/* Unknow packet? */
		default:
			type = *ptr;

			/* Default case means non-HCILL packets,
			 * possibilities are packets for:
			 * (a) valid protocol -  Supported Protocols within
			 *     the ST_MAX_CHANNELS.
			 * (b) registered protocol - Checked by
			 *     "st_gdata->list[type] == NULL)" are supported
			 *     protocols only.
			 *  Rules out any invalid protocol and
			 *  unregistered protocols with channel ID < 16.
			 */

			if ((type >= ST_MAX_CHANNELS) ||
					(st_gdata->list[type] == NULL)) {
				pr_err("chip/interface misbehavior: "
						"dropping frame starting "
						"with 0x%02x\n", type);
				goto done;
			}

			st_gdata->rx_skb = alloc_skb(
					st_gdata->list[type]->max_frame_size,
					GFP_ATOMIC);
			if (st_gdata->rx_skb == NULL) {
				pr_err("out of memory: dropping\n");
				goto done;
			}

			skb_reserve(st_gdata->rx_skb,
					st_gdata->list[type]->reserve);
			/* next 2 required for BT only */
			st_gdata->rx_skb->cb[0] = type; /*pkt_type*/
			st_gdata->rx_skb->cb[1] = 0; /*incoming*/
			st_gdata->rx_chnl = *ptr;
			st_gdata->rx_state = ST_W4_HEADER;
			st_gdata->rx_count = st_gdata->list[type]->hdr_len;
			pr_debug("rx_count %ld\n", st_gdata->rx_count);
		};
		ptr++;
		count--;
	}
done:
	spin_unlock_irqrestore(&st_gdata->lock, flags);
	pr_debug("done %s", __func__);
	return;
}

/**
 * st_int_dequeue - internal de-Q function.
 *	If the previous data set was not written
 *	completely, return that skb which has the pending data.
 *	In normal cases, return top of txq.
 */
static struct sk_buff *st_int_dequeue(struct st_data_s *st_gdata)
{
	struct sk_buff *returning_skb;

	pr_debug("%s", __func__);
	if (st_gdata->tx_skb != NULL) {
		returning_skb = st_gdata->tx_skb;
		st_gdata->tx_skb = NULL;
		return returning_skb;
	}
	return skb_dequeue(&st_gdata->txq);
}

/**
 * st_int_enqueue - internal Q-ing function.
 *	Will either Q the skb to txq or the tx_waitq
 *	depending on the ST LL state.
 *	If the chip is asleep, then Q it onto waitq and
 *	wakeup the chip.
 *	txq and waitq needs protection since the other contexts
 *	may be sending data, waking up chip.
 */
static void st_int_enqueue(struct st_data_s *st_gdata, struct sk_buff *skb)
{
	unsigned long flags = 0;

	pr_debug("%s", __func__);
	spin_lock_irqsave(&st_gdata->lock, flags);

	switch (st_ll_getstate(st_gdata)) {
	case ST_LL_AWAKE:
		pr_debug("ST LL is AWAKE, sending normally");
		skb_queue_tail(&st_gdata->txq, skb);
		break;
	case ST_LL_ASLEEP_TO_AWAKE:
		skb_queue_tail(&st_gdata->tx_waitq, skb);
		break;
	case ST_LL_AWAKE_TO_ASLEEP:
		pr_err("ST LL is illegal state(%ld),"
			   "purging received skb.", st_ll_getstate(st_gdata));
		kfree_skb(skb);
		break;
	case ST_LL_ASLEEP:
		skb_queue_tail(&st_gdata->tx_waitq, skb);
		st_ll_wakeup(st_gdata);
		break;
	default:
		pr_err("ST LL is illegal state(%ld),"
			   "purging received skb.", st_ll_getstate(st_gdata));
		kfree_skb(skb);
		break;
	}

	spin_unlock_irqrestore(&st_gdata->lock, flags);
	pr_debug("done %s", __func__);
	return;
}

/*
 * internal wakeup function
 * called from either
 * - TTY layer when write's finished
 * - st_write (in context of the protocol stack)
 */
void st_tx_wakeup(struct st_data_s *st_data)
{
	struct sk_buff *skb;
	unsigned long flags;	/* for irq save flags */
	pr_debug("%s", __func__);
	/* check for sending & set flag sending here */
	if (test_and_set_bit(ST_TX_SENDING, &st_data->tx_state)) {
		pr_debug("ST already sending");
		/* keep sending */
		set_bit(ST_TX_WAKEUP, &st_data->tx_state);
		return;
		/* TX_WAKEUP will be checked in another
		 * context
		 */
	}
	do {			/* come back if st_tx_wakeup is set */
		/* woke-up to write */
		clear_bit(ST_TX_WAKEUP, &st_data->tx_state);
		while ((skb = st_int_dequeue(st_data))) {
			int len;
			spin_lock_irqsave(&st_data->lock, flags);
			/* enable wake-up from TTY */
			set_bit(TTY_DO_WRITE_WAKEUP, &st_data->tty->flags);
			len = st_int_write(st_data, skb->data, skb->len);
			skb_pull(skb, len);
			/* if skb->len = len as expected, skb->len=0 */
			if (skb->len) {
				/* would be the next skb to be sent */
				st_data->tx_skb = skb;
				spin_unlock_irqrestore(&st_data->lock, flags);
				break;
			}
			kfree_skb(skb);
			spin_unlock_irqrestore(&st_data->lock, flags);
		}
		/* if wake-up is set in another context- restart sending */
	} while (test_bit(ST_TX_WAKEUP, &st_data->tx_state));

	/* clear flag sending */
	clear_bit(ST_TX_SENDING, &st_data->tx_state);
}

/********************************************************************/
/* functions called from ST KIM
*/
void kim_st_list_protocols(struct st_data_s *st_gdata, void *buf)
{
	seq_printf(buf, "[%d]\nBT=%c\nFM=%c\nGPS=%c\n",
			st_gdata->protos_registered,
			st_gdata->is_registered[0x04] == true ? 'R' : 'U',
			st_gdata->is_registered[0x08] == true ? 'R' : 'U',
			st_gdata->is_registered[0x09] == true ? 'R' : 'U');
}

/********************************************************************/
/*
 * functions called from protocol stack drivers
 * to be EXPORT-ed
 */
long st_register(struct st_proto_s *new_proto)
{
	struct st_data_s	*st_gdata;
	long err = 0;
	unsigned long flags = 0;

	st_kim_ref(&st_gdata, 0);
	if (st_gdata == NULL || new_proto == NULL || new_proto->recv == NULL
	    || new_proto->reg_complete_cb == NULL) {
		pr_err("gdata/new_proto/recv or reg_complete_cb not ready");
		return -EINVAL;
	}

	if (new_proto->chnl_id >= ST_MAX_CHANNELS) {
		pr_err("chnl_id %d not supported", new_proto->chnl_id);
		return -EPROTONOSUPPORT;
	}

	if (st_gdata->is_registered[new_proto->chnl_id] == true) {
		pr_err("chnl_id %d already registered", new_proto->chnl_id);
		return -EALREADY;
	}

	/* can be from process context only */
	spin_lock_irqsave(&st_gdata->lock, flags);

	if (test_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state)) {
		pr_info(" ST_REG_IN_PROGRESS:%d ", new_proto->chnl_id);
		/* fw download in progress */

		add_channel_to_table(st_gdata, new_proto);
		st_gdata->protos_registered++;
		new_proto->write = st_write;

		set_bit(ST_REG_PENDING, &st_gdata->st_state);
		spin_unlock_irqrestore(&st_gdata->lock, flags);
		return -EINPROGRESS;
	} else if (st_gdata->protos_registered == ST_EMPTY) {
		pr_info(" chnl_id list empty :%d ", new_proto->chnl_id);
		set_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
		st_recv = st_kim_recv;

		/* enable the ST LL - to set default chip state */
		st_ll_enable(st_gdata);

		/* release lock previously held - re-locked below */
		spin_unlock_irqrestore(&st_gdata->lock, flags);

		/* this may take a while to complete
		 * since it involves BT fw download
		 */
		err = st_kim_start(st_gdata->kim_data);
		if (err != 0) {
			clear_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
			if ((st_gdata->protos_registered != ST_EMPTY) &&
			    (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
				pr_err(" KIM failure complete callback ");
				spin_lock_irqsave(&st_gdata->lock, flags);
				st_reg_complete(st_gdata, err);
				spin_unlock_irqrestore(&st_gdata->lock, flags);
				clear_bit(ST_REG_PENDING, &st_gdata->st_state);
			}
			return -EINVAL;
		}

		spin_lock_irqsave(&st_gdata->lock, flags);

		clear_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
		st_recv = st_int_recv;

		/* this is where all pending registration
		 * are signalled to be complete by calling callback functions
		 */
		if ((st_gdata->protos_registered != ST_EMPTY) &&
		    (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
			pr_debug(" call reg complete callback ");
			st_reg_complete(st_gdata, 0);
		}
		clear_bit(ST_REG_PENDING, &st_gdata->st_state);

		/* check for already registered once more,
		 * since the above check is old
		 */
		if (st_gdata->is_registered[new_proto->chnl_id] == true) {
			pr_err(" proto %d already registered ",
				   new_proto->chnl_id);
			spin_unlock_irqrestore(&st_gdata->lock, flags);
			return -EALREADY;
		}

		add_channel_to_table(st_gdata, new_proto);
		st_gdata->protos_registered++;
		new_proto->write = st_write;
		spin_unlock_irqrestore(&st_gdata->lock, flags);
		return err;
	}
	/* if fw is already downloaded & new stack registers protocol */
	else {
		add_channel_to_table(st_gdata, new_proto);
		st_gdata->protos_registered++;
		new_proto->write = st_write;

		/* lock already held before entering else */
		spin_unlock_irqrestore(&st_gdata->lock, flags);
		return err;
	}
	pr_debug("done %s(%d) ", __func__, new_proto->chnl_id);
}
EXPORT_SYMBOL_GPL(st_register);

/* to unregister a protocol -
 * to be called from protocol stack driver
 */
long st_unregister(struct st_proto_s *proto)
{
	long err = 0;
	unsigned long flags = 0;
	struct st_data_s	*st_gdata;

	pr_debug("%s: %d ", __func__, proto->chnl_id);

	st_kim_ref(&st_gdata, 0);
	if (!st_gdata || proto->chnl_id >= ST_MAX_CHANNELS) {
		pr_err(" chnl_id %d not supported", proto->chnl_id);
		return -EPROTONOSUPPORT;
	}

	spin_lock_irqsave(&st_gdata->lock, flags);

	if (st_gdata->is_registered[proto->chnl_id] == false) {
		pr_err(" chnl_id %d not registered", proto->chnl_id);
		spin_unlock_irqrestore(&st_gdata->lock, flags);
		return -EPROTONOSUPPORT;
	}

	if (st_gdata->protos_registered)
		st_gdata->protos_registered--;

	remove_channel_from_table(st_gdata, proto);
	spin_unlock_irqrestore(&st_gdata->lock, flags);

	if ((st_gdata->protos_registered == ST_EMPTY) &&
	    (!test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
		pr_info(" all chnl_ids unregistered ");

		/* stop traffic on tty */
		if (st_gdata->tty) {
			tty_ldisc_flush(st_gdata->tty);
			stop_tty(st_gdata->tty);
		}

		/* all chnl_ids now unregistered */
		st_kim_stop(st_gdata->kim_data);
		/* disable ST LL */
		st_ll_disable(st_gdata);
	}
	return err;
}

/*
 * called in protocol stack drivers
 * via the write function pointer
 */
long st_write(struct sk_buff *skb)
{
	struct st_data_s *st_gdata;
	long len;

	st_kim_ref(&st_gdata, 0);
	if (unlikely(skb == NULL || st_gdata == NULL
		|| st_gdata->tty == NULL)) {
		pr_err("data/tty unavailable to perform write");
		return -EINVAL;
	}

	pr_debug("%d to be written", skb->len);
	len = skb->len;

	/* st_ll to decide where to enqueue the skb */
	st_int_enqueue(st_gdata, skb);
	/* wake up */
	st_tx_wakeup(st_gdata);

	/* return number of bytes written */
	return len;
}

/* for protocols making use of shared transport */
EXPORT_SYMBOL_GPL(st_unregister);

/********************************************************************/
/*
 * functions called from TTY layer
 */
static int st_tty_open(struct tty_struct *tty)
{
	int err = 0;
	struct st_data_s *st_gdata;
	pr_info("%s ", __func__);

	st_kim_ref(&st_gdata, 0);
	st_gdata->tty = tty;
	tty->disc_data = st_gdata;

	/* don't do an wakeup for now */
	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

	/* mem already allocated
	 */
	tty->receive_room = 65536;
	/* Flush any pending characters in the driver and discipline. */
	tty_ldisc_flush(tty);
	tty_driver_flush_buffer(tty);
	/*
	 * signal to UIM via KIM that -
	 * installation of N_TI_WL ldisc is complete
	 */
	st_kim_complete(st_gdata->kim_data);
	pr_debug("done %s", __func__);
	return err;
}

static void st_tty_close(struct tty_struct *tty)
{
	unsigned char i = ST_MAX_CHANNELS;
	unsigned long flags = 0;
	struct	st_data_s *st_gdata = tty->disc_data;

	pr_info("%s ", __func__);

	/* TODO:
	 * if a protocol has been registered & line discipline
	 * un-installed for some reason - what should be done ?
	 */
	spin_lock_irqsave(&st_gdata->lock, flags);
	for (i = ST_BT; i < ST_MAX_CHANNELS; i++) {
		if (st_gdata->is_registered[i] == true)
			pr_err("%d not un-registered", i);
		st_gdata->list[i] = NULL;
		st_gdata->is_registered[i] = false;
	}
	st_gdata->protos_registered = 0;
	spin_unlock_irqrestore(&st_gdata->lock, flags);
	/*
	 * signal to UIM via KIM that -
	 * N_TI_WL ldisc is un-installed
	 */
	st_kim_complete(st_gdata->kim_data);
	st_gdata->tty = NULL;
	/* Flush any pending characters in the driver and discipline. */
	tty_ldisc_flush(tty);
	tty_driver_flush_buffer(tty);

	spin_lock_irqsave(&st_gdata->lock, flags);
	/* empty out txq and tx_waitq */
	skb_queue_purge(&st_gdata->txq);
	skb_queue_purge(&st_gdata->tx_waitq);
	/* reset the TTY Rx states of ST */
	st_gdata->rx_count = 0;
	st_gdata->rx_state = ST_W4_PACKET_TYPE;
	kfree_skb(st_gdata->rx_skb);
	st_gdata->rx_skb = NULL;
	spin_unlock_irqrestore(&st_gdata->lock, flags);

	pr_debug("%s: done ", __func__);
}

static void st_tty_receive(struct tty_struct *tty, const unsigned char *data,
			   char *tty_flags, int count)
{
#ifdef VERBOSE
	print_hex_dump(KERN_DEBUG, ">in>", DUMP_PREFIX_NONE,
		16, 1, data, count, 0);
#endif

	/*
	 * if fw download is in progress then route incoming data
	 * to KIM for validation
	 */
	st_recv(tty->disc_data, data, count);
	pr_debug("done %s", __func__);
}

/* wake-up function called in from the TTY layer
 * inside the internal wakeup function will be called
 */
static void st_tty_wakeup(struct tty_struct *tty)
{
	struct	st_data_s *st_gdata = tty->disc_data;
	pr_debug("%s ", __func__);
	/* don't do an wakeup for now */
	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

	/* call our internal wakeup */
	st_tx_wakeup((void *)st_gdata);
}

static void st_tty_flush_buffer(struct tty_struct *tty)
{
	struct	st_data_s *st_gdata = tty->disc_data;
	pr_debug("%s ", __func__);

	kfree_skb(st_gdata->tx_skb);
	st_gdata->tx_skb = NULL;

	tty_driver_flush_buffer(tty);
	return;
}

static struct tty_ldisc_ops st_ldisc_ops = {
	.magic = TTY_LDISC_MAGIC,
	.name = "n_st",
	.open = st_tty_open,
	.close = st_tty_close,
	.receive_buf = st_tty_receive,
	.write_wakeup = st_tty_wakeup,
	.flush_buffer = st_tty_flush_buffer,
	.owner = THIS_MODULE
};

/********************************************************************/
int st_core_init(struct st_data_s **core_data)
{
	struct st_data_s *st_gdata;
	long err;

	err = tty_register_ldisc(N_TI_WL, &st_ldisc_ops);
	if (err) {
		pr_err("error registering %d line discipline %ld",
			   N_TI_WL, err);
		return err;
	}
	pr_debug("registered n_shared line discipline");

	st_gdata = kzalloc(sizeof(struct st_data_s), GFP_KERNEL);
	if (!st_gdata) {
		pr_err("memory allocation failed");
		err = tty_unregister_ldisc(N_TI_WL);
		if (err)
			pr_err("unable to un-register ldisc %ld", err);
		err = -ENOMEM;
		return err;
	}

	/* Initialize ST TxQ and Tx waitQ queue head. All BT/FM/GPS module skb's
	 * will be pushed in this queue for actual transmission.
	 */
	skb_queue_head_init(&st_gdata->txq);
	skb_queue_head_init(&st_gdata->tx_waitq);

	/* Locking used in st_int_enqueue() to avoid multiple execution */
	spin_lock_init(&st_gdata->lock);

	err = st_ll_init(st_gdata);
	if (err) {
		pr_err("error during st_ll initialization(%ld)", err);
		kfree(st_gdata);
		err = tty_unregister_ldisc(N_TI_WL);
		if (err)
			pr_err("unable to un-register ldisc");
		return err;
	}
	*core_data = st_gdata;
	return 0;
}

void st_core_exit(struct st_data_s *st_gdata)
{
	long err;
	/* internal module cleanup */
	err = st_ll_deinit(st_gdata);
	if (err)
		pr_err("error during deinit of ST LL %ld", err);

	if (st_gdata != NULL) {
		/* Free ST Tx Qs and skbs */
		skb_queue_purge(&st_gdata->txq);
		skb_queue_purge(&st_gdata->tx_waitq);
		kfree_skb(st_gdata->rx_skb);
		kfree_skb(st_gdata->tx_skb);
		/* TTY ldisc cleanup */
		err = tty_unregister_ldisc(N_TI_WL);
		if (err)
			pr_err("unable to un-register ldisc %ld", err);
		/* free the global data pointer */
		kfree(st_gdata);
	}
}