summaryrefslogtreecommitdiff
path: root/drivers/hwtracing/coresight/coresight.c
blob: b8091bef21dc79085c450c783b5784d229c3b333 (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
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
/* Copyright (c) 2012, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only 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.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/clk.h>
#include <linux/coresight.h>
#include <linux/of_platform.h>
#include <linux/delay.h>
#include <linux/pm_runtime.h>

#include "coresight-priv.h"

static DEFINE_MUTEX(coresight_mutex);

/**
 * struct coresight_node - elements of a path, from source to sink
 * @csdev:	Address of an element.
 * @link:	hook to the list.
 */
struct coresight_node {
	struct coresight_device *csdev;
	struct list_head link;
};

/*
 * When operating Coresight drivers from the sysFS interface, only a single
 * path can exist from a tracer (associated to a CPU) to a sink.
 */
static DEFINE_PER_CPU(struct list_head *, tracer_path);

/*
 * As of this writing only a single STM can be found in CS topologies.  Since
 * there is no way to know if we'll ever see more and what kind of
 * configuration they will enact, for the time being only define a single path
 * for STM.
 */
static struct list_head *stm_path;

/*
 * When losing synchronisation a new barrier packet needs to be inserted at the
 * beginning of the data collected in a buffer.  That way the decoder knows that
 * it needs to look for another sync sequence.
 */
const u32 barrier_pkt[5] = {0x7fffffff, 0x7fffffff,
			    0x7fffffff, 0x7fffffff, 0x0};

static int coresight_id_match(struct device *dev, void *data)
{
	int trace_id, i_trace_id;
	struct coresight_device *csdev, *i_csdev;

	csdev = data;
	i_csdev = to_coresight_device(dev);

	/*
	 * No need to care about oneself and components that are not
	 * sources or not enabled
	 */
	if (i_csdev == csdev || !i_csdev->enable ||
	    i_csdev->type != CORESIGHT_DEV_TYPE_SOURCE)
		return 0;

	/* Get the source ID for both compoment */
	trace_id = source_ops(csdev)->trace_id(csdev);
	i_trace_id = source_ops(i_csdev)->trace_id(i_csdev);

	/* All you need is one */
	if (trace_id == i_trace_id)
		return 1;

	return 0;
}

static int coresight_source_is_unique(struct coresight_device *csdev)
{
	int trace_id = source_ops(csdev)->trace_id(csdev);

	/* this shouldn't happen */
	if (trace_id < 0)
		return 0;

	return !bus_for_each_dev(&coresight_bustype, NULL,
				 csdev, coresight_id_match);
}

static int coresight_find_link_inport(struct coresight_device *csdev,
				      struct coresight_device *parent)
{
	int i;
	struct coresight_connection *conn;

	for (i = 0; i < parent->nr_outport; i++) {
		conn = &parent->conns[i];
		if (conn->child_dev == csdev)
			return conn->child_port;
	}

	dev_err(&csdev->dev, "couldn't find inport, parent: %s, child: %s\n",
		dev_name(&parent->dev), dev_name(&csdev->dev));

	return 0;
}

static int coresight_find_link_outport(struct coresight_device *csdev,
				       struct coresight_device *child)
{
	int i;
	struct coresight_connection *conn;

	for (i = 0; i < csdev->nr_outport; i++) {
		conn = &csdev->conns[i];
		if (conn->child_dev == child)
			return conn->outport;
	}

	dev_err(&csdev->dev, "couldn't find outport, parent: %s, child: %s\n",
		dev_name(&csdev->dev), dev_name(&child->dev));

	return 0;
}

static int coresight_enable_sink(struct coresight_device *csdev, u32 mode)
{
	int ret;

	if (!csdev->enable) {
		if (sink_ops(csdev)->enable) {
			ret = sink_ops(csdev)->enable(csdev, mode);
			if (ret)
				return ret;
		}
		csdev->enable = true;
	}

	atomic_inc(csdev->refcnt);

	return 0;
}

static void coresight_disable_sink(struct coresight_device *csdev)
{
	if (atomic_dec_return(csdev->refcnt) == 0) {
		if (sink_ops(csdev)->disable) {
			sink_ops(csdev)->disable(csdev);
			csdev->enable = false;
		}
	}
}

static int coresight_enable_link(struct coresight_device *csdev,
				 struct coresight_device *parent,
				 struct coresight_device *child)
{
	int ret;
	int link_subtype;
	int refport, inport, outport;

	if (!parent || !child)
		return -EINVAL;

	inport = coresight_find_link_inport(csdev, parent);
	outport = coresight_find_link_outport(csdev, child);
	link_subtype = csdev->subtype.link_subtype;

	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG)
		refport = inport;
	else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT)
		refport = outport;
	else
		refport = 0;

	if (atomic_inc_return(&csdev->refcnt[refport]) == 1) {
		if (link_ops(csdev)->enable) {
			ret = link_ops(csdev)->enable(csdev, inport, outport);
			if (ret)
				return ret;
		}
	}

	csdev->enable = true;

	return 0;
}

static void coresight_disable_link(struct coresight_device *csdev,
				   struct coresight_device *parent,
				   struct coresight_device *child)
{
	int i, nr_conns;
	int link_subtype;
	int refport, inport, outport;

	if (!parent || !child)
		return;

	inport = coresight_find_link_inport(csdev, parent);
	outport = coresight_find_link_outport(csdev, child);
	link_subtype = csdev->subtype.link_subtype;

	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG) {
		refport = inport;
		nr_conns = csdev->nr_inport;
	} else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT) {
		refport = outport;
		nr_conns = csdev->nr_outport;
	} else {
		refport = 0;
		nr_conns = 1;
	}

	if (atomic_dec_return(&csdev->refcnt[refport]) == 0) {
		if (link_ops(csdev)->disable)
			link_ops(csdev)->disable(csdev, inport, outport);
	}

	for (i = 0; i < nr_conns; i++)
		if (atomic_read(&csdev->refcnt[i]) != 0)
			return;

	csdev->enable = false;
}

static int coresight_enable_source(struct coresight_device *csdev, u32 mode)
{
	int ret;

	if (!coresight_source_is_unique(csdev)) {
		dev_warn(&csdev->dev, "traceID %d not unique\n",
			 source_ops(csdev)->trace_id(csdev));
		return -EINVAL;
	}

	if (!csdev->enable) {
		if (source_ops(csdev)->enable) {
			ret = source_ops(csdev)->enable(csdev, NULL, mode);
			if (ret)
				return ret;
		}
		csdev->enable = true;
	}

	atomic_inc(csdev->refcnt);

	return 0;
}

/**
 *  coresight_disable_source - Drop the reference count by 1 and disable
 *  the device if there are no users left.
 *
 *  @csdev - The coresight device to disable
 *
 *  Returns true if the device has been disabled.
 */
static bool coresight_disable_source(struct coresight_device *csdev)
{
	if (atomic_dec_return(csdev->refcnt) == 0) {
		if (source_ops(csdev)->disable)
			source_ops(csdev)->disable(csdev, NULL);
		csdev->enable = false;
	}
	return !csdev->enable;
}

void coresight_disable_path(struct list_head *path)
{
	u32 type;
	struct coresight_node *nd;
	struct coresight_device *csdev, *parent, *child;

	list_for_each_entry(nd, path, link) {
		csdev = nd->csdev;
		type = csdev->type;

		/*
		 * ETF devices are tricky... They can be a link or a sink,
		 * depending on how they are configured.  If an ETF has been
		 * "activated" it will be configured as a sink, otherwise
		 * go ahead with the link configuration.
		 */
		if (type == CORESIGHT_DEV_TYPE_LINKSINK)
			type = (csdev == coresight_get_sink(path)) ?
						CORESIGHT_DEV_TYPE_SINK :
						CORESIGHT_DEV_TYPE_LINK;

		switch (type) {
		case CORESIGHT_DEV_TYPE_SINK:
			coresight_disable_sink(csdev);
			break;
		case CORESIGHT_DEV_TYPE_SOURCE:
			/* sources are disabled from either sysFS or Perf */
			break;
		case CORESIGHT_DEV_TYPE_LINK:
			parent = list_prev_entry(nd, link)->csdev;
			child = list_next_entry(nd, link)->csdev;
			coresight_disable_link(csdev, parent, child);
			break;
		default:
			break;
		}
	}
}

int coresight_enable_path(struct list_head *path, u32 mode)
{

	int ret = 0;
	u32 type;
	struct coresight_node *nd;
	struct coresight_device *csdev, *parent, *child;

	list_for_each_entry_reverse(nd, path, link) {
		csdev = nd->csdev;
		type = csdev->type;

		/*
		 * ETF devices are tricky... They can be a link or a sink,
		 * depending on how they are configured.  If an ETF has been
		 * "activated" it will be configured as a sink, otherwise
		 * go ahead with the link configuration.
		 */
		if (type == CORESIGHT_DEV_TYPE_LINKSINK)
			type = (csdev == coresight_get_sink(path)) ?
						CORESIGHT_DEV_TYPE_SINK :
						CORESIGHT_DEV_TYPE_LINK;

		switch (type) {
		case CORESIGHT_DEV_TYPE_SINK:
			ret = coresight_enable_sink(csdev, mode);
			if (ret)
				goto err;
			break;
		case CORESIGHT_DEV_TYPE_SOURCE:
			/* sources are enabled from either sysFS or Perf */
			break;
		case CORESIGHT_DEV_TYPE_LINK:
			parent = list_prev_entry(nd, link)->csdev;
			child = list_next_entry(nd, link)->csdev;
			ret = coresight_enable_link(csdev, parent, child);
			if (ret)
				goto err;
			break;
		default:
			goto err;
		}
	}

out:
	return ret;
err:
	coresight_disable_path(path);
	goto out;
}

struct coresight_device *coresight_get_sink(struct list_head *path)
{
	struct coresight_device *csdev;

	if (!path)
		return NULL;

	csdev = list_last_entry(path, struct coresight_node, link)->csdev;
	if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
	    csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
		return NULL;

	return csdev;
}

static int coresight_enabled_sink(struct device *dev, void *data)
{
	bool *reset = data;
	struct coresight_device *csdev = to_coresight_device(dev);

	if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||
	     csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) &&
	     csdev->activated) {
		/*
		 * Now that we have a handle on the sink for this session,
		 * disable the sysFS "enable_sink" flag so that possible
		 * concurrent perf session that wish to use another sink don't
		 * trip on it.  Doing so has no ramification for the current
		 * session.
		 */
		if (*reset)
			csdev->activated = false;

		return 1;
	}

	return 0;
}

/**
 * coresight_get_enabled_sink - returns the first enabled sink found on the bus
 * @deactivate:	Whether the 'enable_sink' flag should be reset
 *
 * When operated from perf the deactivate parameter should be set to 'true'.
 * That way the "enabled_sink" flag of the sink that was selected can be reset,
 * allowing for other concurrent perf sessions to choose a different sink.
 *
 * When operated from sysFS users have full control and as such the deactivate
 * parameter should be set to 'false', hence mandating users to explicitly
 * clear the flag.
 */
struct coresight_device *coresight_get_enabled_sink(bool deactivate)
{
	struct device *dev = NULL;

	dev = bus_find_device(&coresight_bustype, NULL, &deactivate,
			      coresight_enabled_sink);

	return dev ? to_coresight_device(dev) : NULL;
}

/**
 * _coresight_build_path - recursively build a path from a @csdev to a sink.
 * @csdev:	The device to start from.
 * @path:	The list to add devices to.
 *
 * The tree of Coresight device is traversed until an activated sink is
 * found.  From there the sink is added to the list along with all the
 * devices that led to that point - the end result is a list from source
 * to sink. In that list the source is the first device and the sink the
 * last one.
 */
static int _coresight_build_path(struct coresight_device *csdev,
				 struct coresight_device *sink,
				 struct list_head *path)
{
	int i;
	bool found = false;
	struct coresight_node *node;

	/* An activated sink has been found.  Enqueue the element */
	if (csdev == sink)
		goto out;

	/* Not a sink - recursively explore each port found on this element */
	for (i = 0; i < csdev->nr_outport; i++) {
		struct coresight_device *child_dev = csdev->conns[i].child_dev;

		if (child_dev &&
		    _coresight_build_path(child_dev, sink, path) == 0) {
			found = true;
			break;
		}
	}

	if (!found)
		return -ENODEV;

out:
	/*
	 * A path from this element to a sink has been found.  The elements
	 * leading to the sink are already enqueued, all that is left to do
	 * is tell the PM runtime core we need this element and add a node
	 * for it.
	 */
	node = kzalloc(sizeof(struct coresight_node), GFP_KERNEL);
	if (!node)
		return -ENOMEM;

	node->csdev = csdev;
	list_add(&node->link, path);
	pm_runtime_get_sync(csdev->dev.parent);

	return 0;
}

struct list_head *coresight_build_path(struct coresight_device *source,
				       struct coresight_device *sink)
{
	struct list_head *path;
	int rc;

	if (!sink)
		return ERR_PTR(-EINVAL);

	path = kzalloc(sizeof(struct list_head), GFP_KERNEL);
	if (!path)
		return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(path);

	rc = _coresight_build_path(source, sink, path);
	if (rc) {
		kfree(path);
		return ERR_PTR(rc);
	}

	return path;
}

/**
 * coresight_release_path - release a previously built path.
 * @path:	the path to release.
 *
 * Go through all the elements of a path and 1) removed it from the list and
 * 2) free the memory allocated for each node.
 */
void coresight_release_path(struct list_head *path)
{
	struct coresight_device *csdev;
	struct coresight_node *nd, *next;

	list_for_each_entry_safe(nd, next, path, link) {
		csdev = nd->csdev;

		pm_runtime_put_sync(csdev->dev.parent);
		list_del(&nd->link);
		kfree(nd);
	}

	kfree(path);
	path = NULL;
}

/** coresight_validate_source - make sure a source has the right credentials
 *  @csdev:	the device structure for a source.
 *  @function:	the function this was called from.
 *
 * Assumes the coresight_mutex is held.
 */
static int coresight_validate_source(struct coresight_device *csdev,
				     const char *function)
{
	u32 type, subtype;

	type = csdev->type;
	subtype = csdev->subtype.source_subtype;

	if (type != CORESIGHT_DEV_TYPE_SOURCE) {
		dev_err(&csdev->dev, "wrong device type in %s\n", function);
		return -EINVAL;
	}

	if (subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_PROC &&
	    subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE) {
		dev_err(&csdev->dev, "wrong device subtype in %s\n", function);
		return -EINVAL;
	}

	return 0;
}

int coresight_enable(struct coresight_device *csdev)
{
	int cpu, ret = 0;
	struct coresight_device *sink;
	struct list_head *path;
	enum coresight_dev_subtype_source subtype;

	subtype = csdev->subtype.source_subtype;

	mutex_lock(&coresight_mutex);

	ret = coresight_validate_source(csdev, __func__);
	if (ret)
		goto out;

	if (csdev->enable) {
		/*
		 * There could be multiple applications driving the software
		 * source. So keep the refcount for each such user when the
		 * source is already enabled.
		 */
		if (subtype == CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE)
			atomic_inc(csdev->refcnt);
		goto out;
	}

	/*
	 * Search for a valid sink for this session but don't reset the
	 * "enable_sink" flag in sysFS.  Users get to do that explicitly.
	 */
	sink = coresight_get_enabled_sink(false);
	if (!sink) {
		ret = -EINVAL;
		goto out;
	}

	path = coresight_build_path(csdev, sink);
	if (IS_ERR(path)) {
		pr_err("building path(s) failed\n");
		ret = PTR_ERR(path);
		goto out;
	}

	ret = coresight_enable_path(path, CS_MODE_SYSFS);
	if (ret)
		goto err_path;

	ret = coresight_enable_source(csdev, CS_MODE_SYSFS);
	if (ret)
		goto err_source;

	switch (subtype) {
	case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
		/*
		 * When working from sysFS it is important to keep track
		 * of the paths that were created so that they can be
		 * undone in 'coresight_disable()'.  Since there can only
		 * be a single session per tracer (when working from sysFS)
		 * a per-cpu variable will do just fine.
		 */
		cpu = source_ops(csdev)->cpu_id(csdev);
		per_cpu(tracer_path, cpu) = path;
		break;
	case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
		stm_path = path;
		break;
	default:
		/* We can't be here */
		break;
	}

out:
	mutex_unlock(&coresight_mutex);
	return ret;

err_source:
	coresight_disable_path(path);

err_path:
	coresight_release_path(path);
	goto out;
}
EXPORT_SYMBOL_GPL(coresight_enable);

void coresight_disable(struct coresight_device *csdev)
{
	int cpu, ret;
	struct list_head *path = NULL;

	mutex_lock(&coresight_mutex);

	ret = coresight_validate_source(csdev, __func__);
	if (ret)
		goto out;

	if (!csdev->enable || !coresight_disable_source(csdev))
		goto out;

	switch (csdev->subtype.source_subtype) {
	case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
		cpu = source_ops(csdev)->cpu_id(csdev);
		path = per_cpu(tracer_path, cpu);
		per_cpu(tracer_path, cpu) = NULL;
		break;
	case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
		path = stm_path;
		stm_path = NULL;
		break;
	default:
		/* We can't be here */
		break;
	}

	coresight_disable_path(path);
	coresight_release_path(path);

out:
	mutex_unlock(&coresight_mutex);
}
EXPORT_SYMBOL_GPL(coresight_disable);

static ssize_t enable_sink_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct coresight_device *csdev = to_coresight_device(dev);

	return scnprintf(buf, PAGE_SIZE, "%u\n", csdev->activated);
}

static ssize_t enable_sink_store(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf, size_t size)
{
	int ret;
	unsigned long val;
	struct coresight_device *csdev = to_coresight_device(dev);

	ret = kstrtoul(buf, 10, &val);
	if (ret)
		return ret;

	if (val)
		csdev->activated = true;
	else
		csdev->activated = false;

	return size;

}
static DEVICE_ATTR_RW(enable_sink);

static ssize_t enable_source_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	struct coresight_device *csdev = to_coresight_device(dev);

	return scnprintf(buf, PAGE_SIZE, "%u\n", csdev->enable);
}

static ssize_t enable_source_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf, size_t size)
{
	int ret = 0;
	unsigned long val;
	struct coresight_device *csdev = to_coresight_device(dev);

	ret = kstrtoul(buf, 10, &val);
	if (ret)
		return ret;

	if (val) {
		ret = coresight_enable(csdev);
		if (ret)
			return ret;
	} else {
		coresight_disable(csdev);
	}

	return size;
}
static DEVICE_ATTR_RW(enable_source);

static struct attribute *coresight_sink_attrs[] = {
	&dev_attr_enable_sink.attr,
	NULL,
};
ATTRIBUTE_GROUPS(coresight_sink);

static struct attribute *coresight_source_attrs[] = {
	&dev_attr_enable_source.attr,
	NULL,
};
ATTRIBUTE_GROUPS(coresight_source);

static struct device_type coresight_dev_type[] = {
	{
		.name = "none",
	},
	{
		.name = "sink",
		.groups = coresight_sink_groups,
	},
	{
		.name = "link",
	},
	{
		.name = "linksink",
		.groups = coresight_sink_groups,
	},
	{
		.name = "source",
		.groups = coresight_source_groups,
	},
};

static void coresight_device_release(struct device *dev)
{
	struct coresight_device *csdev = to_coresight_device(dev);

	kfree(csdev->conns);
	kfree(csdev->refcnt);
	kfree(csdev);
}

static int coresight_orphan_match(struct device *dev, void *data)
{
	int i;
	bool still_orphan = false;
	struct coresight_device *csdev, *i_csdev;
	struct coresight_connection *conn;

	csdev = data;
	i_csdev = to_coresight_device(dev);

	/* No need to check oneself */
	if (csdev == i_csdev)
		return 0;

	/* Move on to another component if no connection is orphan */
	if (!i_csdev->orphan)
		return 0;
	/*
	 * Circle throuch all the connection of that component.  If we find
	 * an orphan connection whose name matches @csdev, link it.
	 */
	for (i = 0; i < i_csdev->nr_outport; i++) {
		conn = &i_csdev->conns[i];

		/* We have found at least one orphan connection */
		if (conn->child_dev == NULL) {
			/* Does it match this newly added device? */
			if (conn->child_name &&
			    !strcmp(dev_name(&csdev->dev), conn->child_name)) {
				conn->child_dev = csdev;
			} else {
				/* This component still has an orphan */
				still_orphan = true;
			}
		}
	}

	i_csdev->orphan = still_orphan;

	/*
	 * Returning '0' ensures that all known component on the
	 * bus will be checked.
	 */
	return 0;
}

static void coresight_fixup_orphan_conns(struct coresight_device *csdev)
{
	/*
	 * No need to check for a return value as orphan connection(s)
	 * are hooked-up with each newly added component.
	 */
	bus_for_each_dev(&coresight_bustype, NULL,
			 csdev, coresight_orphan_match);
}


static int coresight_name_match(struct device *dev, void *data)
{
	char *to_match;
	struct coresight_device *i_csdev;

	to_match = data;
	i_csdev = to_coresight_device(dev);

	if (to_match && !strcmp(to_match, dev_name(&i_csdev->dev)))
		return 1;

	return 0;
}

static void coresight_fixup_device_conns(struct coresight_device *csdev)
{
	int i;
	struct device *dev = NULL;
	struct coresight_connection *conn;

	for (i = 0; i < csdev->nr_outport; i++) {
		conn = &csdev->conns[i];
		dev = bus_find_device(&coresight_bustype, NULL,
				      (void *)conn->child_name,
				      coresight_name_match);

		if (dev) {
			conn->child_dev = to_coresight_device(dev);
			/* and put reference from 'bus_find_device()' */
			put_device(dev);
		} else {
			csdev->orphan = true;
			conn->child_dev = NULL;
		}
	}
}

static int coresight_remove_match(struct device *dev, void *data)
{
	int i;
	struct coresight_device *csdev, *iterator;
	struct coresight_connection *conn;

	csdev = data;
	iterator = to_coresight_device(dev);

	/* No need to check oneself */
	if (csdev == iterator)
		return 0;

	/*
	 * Circle throuch all the connection of that component.  If we find
	 * a connection whose name matches @csdev, remove it.
	 */
	for (i = 0; i < iterator->nr_outport; i++) {
		conn = &iterator->conns[i];

		if (conn->child_dev == NULL)
			continue;

		if (!strcmp(dev_name(&csdev->dev), conn->child_name)) {
			iterator->orphan = true;
			conn->child_dev = NULL;
			/* No need to continue */
			break;
		}
	}

	/*
	 * Returning '0' ensures that all known component on the
	 * bus will be checked.
	 */
	return 0;
}

static void coresight_remove_conns(struct coresight_device *csdev)
{
	bus_for_each_dev(&coresight_bustype, NULL,
			 csdev, coresight_remove_match);
}

/**
 * coresight_timeout - loop until a bit has changed to a specific state.
 * @addr: base address of the area of interest.
 * @offset: address of a register, starting from @addr.
 * @position: the position of the bit of interest.
 * @value: the value the bit should have.
 *
 * Return: 0 as soon as the bit has taken the desired state or -EAGAIN if
 * TIMEOUT_US has elapsed, which ever happens first.
 */

int coresight_timeout(void __iomem *addr, u32 offset, int position, int value)
{
	int i;
	u32 val;

	for (i = TIMEOUT_US; i > 0; i--) {
		val = __raw_readl(addr + offset);
		/* waiting on the bit to go from 0 to 1 */
		if (value) {
			if (val & BIT(position))
				return 0;
		/* waiting on the bit to go from 1 to 0 */
		} else {
			if (!(val & BIT(position)))
				return 0;
		}

		/*
		 * Delay is arbitrary - the specification doesn't say how long
		 * we are expected to wait.  Extra check required to make sure
		 * we don't wait needlessly on the last iteration.
		 */
		if (i - 1)
			udelay(1);
	}

	return -EAGAIN;
}

struct bus_type coresight_bustype = {
	.name	= "coresight",
};

static int __init coresight_init(void)
{
	return bus_register(&coresight_bustype);
}
postcore_initcall(coresight_init);

struct coresight_device *coresight_register(struct coresight_desc *desc)
{
	int i;
	int ret;
	int link_subtype;
	int nr_refcnts = 1;
	atomic_t *refcnts = NULL;
	struct coresight_device *csdev;
	struct coresight_connection *conns = NULL;

	csdev = kzalloc(sizeof(*csdev), GFP_KERNEL);
	if (!csdev) {
		ret = -ENOMEM;
		goto err_kzalloc_csdev;
	}

	if (desc->type == CORESIGHT_DEV_TYPE_LINK ||
	    desc->type == CORESIGHT_DEV_TYPE_LINKSINK) {
		link_subtype = desc->subtype.link_subtype;

		if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG)
			nr_refcnts = desc->pdata->nr_inport;
		else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT)
			nr_refcnts = desc->pdata->nr_outport;
	}

	refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL);
	if (!refcnts) {
		ret = -ENOMEM;
		goto err_kzalloc_refcnts;
	}

	csdev->refcnt = refcnts;

	csdev->nr_inport = desc->pdata->nr_inport;
	csdev->nr_outport = desc->pdata->nr_outport;

	/* Initialise connections if there is at least one outport */
	if (csdev->nr_outport) {
		conns = kcalloc(csdev->nr_outport, sizeof(*conns), GFP_KERNEL);
		if (!conns) {
			ret = -ENOMEM;
			goto err_kzalloc_conns;
		}

		for (i = 0; i < csdev->nr_outport; i++) {
			conns[i].outport = desc->pdata->outports[i];
			conns[i].child_name = desc->pdata->child_names[i];
			conns[i].child_port = desc->pdata->child_ports[i];
		}
	}

	csdev->conns = conns;

	csdev->type = desc->type;
	csdev->subtype = desc->subtype;
	csdev->ops = desc->ops;
	csdev->orphan = false;

	csdev->dev.type = &coresight_dev_type[desc->type];
	csdev->dev.groups = desc->groups;
	csdev->dev.parent = desc->dev;
	csdev->dev.release = coresight_device_release;
	csdev->dev.bus = &coresight_bustype;
	dev_set_name(&csdev->dev, "%s", desc->pdata->name);

	ret = device_register(&csdev->dev);
	if (ret)
		goto err_device_register;

	mutex_lock(&coresight_mutex);

	coresight_fixup_device_conns(csdev);
	coresight_fixup_orphan_conns(csdev);

	mutex_unlock(&coresight_mutex);

	return csdev;

err_device_register:
	kfree(conns);
err_kzalloc_conns:
	kfree(refcnts);
err_kzalloc_refcnts:
	kfree(csdev);
err_kzalloc_csdev:
	return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(coresight_register);

void coresight_unregister(struct coresight_device *csdev)
{
	/* Remove references of that device in the topology */
	coresight_remove_conns(csdev);
	device_unregister(&csdev->dev);
}
EXPORT_SYMBOL_GPL(coresight_unregister);