summaryrefslogtreecommitdiff
path: root/drivers/reset/core.c
blob: 7597c70e04d5b42b54d18a8c7de022bc7586b99a (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Reset Controller framework
 *
 * Copyright 2013 Philipp Zabel, Pengutronix
 */
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/reset.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>

static DEFINE_MUTEX(reset_list_mutex);
static LIST_HEAD(reset_controller_list);

static DEFINE_MUTEX(reset_lookup_mutex);
static LIST_HEAD(reset_lookup_list);

/**
 * struct reset_control - a reset control
 * @rcdev: a pointer to the reset controller device
 *         this reset control belongs to
 * @list: list entry for the rcdev's reset controller list
 * @id: ID of the reset controller in the reset
 *      controller device
 * @refcnt: Number of gets of this reset_control
 * @acquired: Only one reset_control may be acquired for a given rcdev and id.
 * @shared: Is this a shared (1), or an exclusive (0) reset_control?
 * @deassert_cnt: Number of times this reset line has been deasserted
 * @triggered_count: Number of times this reset line has been reset. Currently
 *                   only used for shared resets, which means that the value
 *                   will be either 0 or 1.
 */
struct reset_control {
	struct reset_controller_dev *rcdev;
	struct list_head list;
	unsigned int id;
	struct kref refcnt;
	bool acquired;
	bool shared;
	bool array;
	atomic_t deassert_count;
	atomic_t triggered_count;
};

/**
 * struct reset_control_array - an array of reset controls
 * @base: reset control for compatibility with reset control API functions
 * @num_rstcs: number of reset controls
 * @rstc: array of reset controls
 */
struct reset_control_array {
	struct reset_control base;
	unsigned int num_rstcs;
	struct reset_control *rstc[];
};

static const char *rcdev_name(struct reset_controller_dev *rcdev)
{
	if (rcdev->dev)
		return dev_name(rcdev->dev);

	if (rcdev->of_node)
		return rcdev->of_node->full_name;

	return NULL;
}

/**
 * of_reset_simple_xlate - translate reset_spec to the reset line number
 * @rcdev: a pointer to the reset controller device
 * @reset_spec: reset line specifier as found in the device tree
 *
 * This static translation function is used by default if of_xlate in
 * :c:type:`reset_controller_dev` is not set. It is useful for all reset
 * controllers with 1:1 mapping, where reset lines can be indexed by number
 * without gaps.
 */
static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
			  const struct of_phandle_args *reset_spec)
{
	if (reset_spec->args[0] >= rcdev->nr_resets)
		return -EINVAL;

	return reset_spec->args[0];
}

/**
 * reset_controller_register - register a reset controller device
 * @rcdev: a pointer to the initialized reset controller device
 */
int reset_controller_register(struct reset_controller_dev *rcdev)
{
	if (!rcdev->of_xlate) {
		rcdev->of_reset_n_cells = 1;
		rcdev->of_xlate = of_reset_simple_xlate;
	}

	INIT_LIST_HEAD(&rcdev->reset_control_head);

	mutex_lock(&reset_list_mutex);
	list_add(&rcdev->list, &reset_controller_list);
	mutex_unlock(&reset_list_mutex);

	return 0;
}
EXPORT_SYMBOL_GPL(reset_controller_register);

/**
 * reset_controller_unregister - unregister a reset controller device
 * @rcdev: a pointer to the reset controller device
 */
void reset_controller_unregister(struct reset_controller_dev *rcdev)
{
	mutex_lock(&reset_list_mutex);
	list_del(&rcdev->list);
	mutex_unlock(&reset_list_mutex);
}
EXPORT_SYMBOL_GPL(reset_controller_unregister);

static void devm_reset_controller_release(struct device *dev, void *res)
{
	reset_controller_unregister(*(struct reset_controller_dev **)res);
}

/**
 * devm_reset_controller_register - resource managed reset_controller_register()
 * @dev: device that is registering this reset controller
 * @rcdev: a pointer to the initialized reset controller device
 *
 * Managed reset_controller_register(). For reset controllers registered by
 * this function, reset_controller_unregister() is automatically called on
 * driver detach. See reset_controller_register() for more information.
 */
int devm_reset_controller_register(struct device *dev,
				   struct reset_controller_dev *rcdev)
{
	struct reset_controller_dev **rcdevp;
	int ret;

	rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
			      GFP_KERNEL);
	if (!rcdevp)
		return -ENOMEM;

	ret = reset_controller_register(rcdev);
	if (!ret) {
		*rcdevp = rcdev;
		devres_add(dev, rcdevp);
	} else {
		devres_free(rcdevp);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(devm_reset_controller_register);

/**
 * reset_controller_add_lookup - register a set of lookup entries
 * @lookup: array of reset lookup entries
 * @num_entries: number of entries in the lookup array
 */
void reset_controller_add_lookup(struct reset_control_lookup *lookup,
				 unsigned int num_entries)
{
	struct reset_control_lookup *entry;
	unsigned int i;

	mutex_lock(&reset_lookup_mutex);
	for (i = 0; i < num_entries; i++) {
		entry = &lookup[i];

		if (!entry->dev_id || !entry->provider) {
			pr_warn("%s(): reset lookup entry badly specified, skipping\n",
				__func__);
			continue;
		}

		list_add_tail(&entry->list, &reset_lookup_list);
	}
	mutex_unlock(&reset_lookup_mutex);
}
EXPORT_SYMBOL_GPL(reset_controller_add_lookup);

static inline struct reset_control_array *
rstc_to_array(struct reset_control *rstc) {
	return container_of(rstc, struct reset_control_array, base);
}

static int reset_control_array_reset(struct reset_control_array *resets)
{
	int ret, i;

	for (i = 0; i < resets->num_rstcs; i++) {
		ret = reset_control_reset(resets->rstc[i]);
		if (ret)
			return ret;
	}

	return 0;
}

static int reset_control_array_assert(struct reset_control_array *resets)
{
	int ret, i;

	for (i = 0; i < resets->num_rstcs; i++) {
		ret = reset_control_assert(resets->rstc[i]);
		if (ret)
			goto err;
	}

	return 0;

err:
	while (i--)
		reset_control_deassert(resets->rstc[i]);
	return ret;
}

static int reset_control_array_deassert(struct reset_control_array *resets)
{
	int ret, i;

	for (i = 0; i < resets->num_rstcs; i++) {
		ret = reset_control_deassert(resets->rstc[i]);
		if (ret)
			goto err;
	}

	return 0;

err:
	while (i--)
		reset_control_assert(resets->rstc[i]);
	return ret;
}

static int reset_control_array_acquire(struct reset_control_array *resets)
{
	unsigned int i;
	int err;

	for (i = 0; i < resets->num_rstcs; i++) {
		err = reset_control_acquire(resets->rstc[i]);
		if (err < 0)
			goto release;
	}

	return 0;

release:
	while (i--)
		reset_control_release(resets->rstc[i]);

	return err;
}

static void reset_control_array_release(struct reset_control_array *resets)
{
	unsigned int i;

	for (i = 0; i < resets->num_rstcs; i++)
		reset_control_release(resets->rstc[i]);
}

static inline bool reset_control_is_array(struct reset_control *rstc)
{
	return rstc->array;
}

/**
 * reset_control_reset - reset the controlled device
 * @rstc: reset controller
 *
 * On a shared reset line the actual reset pulse is only triggered once for the
 * lifetime of the reset_control instance: for all but the first caller this is
 * a no-op.
 * Consumers must not use reset_control_(de)assert on shared reset lines when
 * reset_control_reset has been used.
 *
 * If rstc is NULL it is an optional reset and the function will just
 * return 0.
 */
int reset_control_reset(struct reset_control *rstc)
{
	int ret;

	if (!rstc)
		return 0;

	if (WARN_ON(IS_ERR(rstc)))
		return -EINVAL;

	if (reset_control_is_array(rstc))
		return reset_control_array_reset(rstc_to_array(rstc));

	if (!rstc->rcdev->ops->reset)
		return -ENOTSUPP;

	if (rstc->shared) {
		if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
			return -EINVAL;

		if (atomic_inc_return(&rstc->triggered_count) != 1)
			return 0;
	} else {
		if (!rstc->acquired)
			return -EPERM;
	}

	ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
	if (rstc->shared && ret)
		atomic_dec(&rstc->triggered_count);

	return ret;
}
EXPORT_SYMBOL_GPL(reset_control_reset);

/**
 * reset_control_assert - asserts the reset line
 * @rstc: reset controller
 *
 * Calling this on an exclusive reset controller guarantees that the reset
 * will be asserted. When called on a shared reset controller the line may
 * still be deasserted, as long as other users keep it so.
 *
 * For shared reset controls a driver cannot expect the hw's registers and
 * internal state to be reset, but must be prepared for this to happen.
 * Consumers must not use reset_control_reset on shared reset lines when
 * reset_control_(de)assert has been used.
 *
 * If rstc is NULL it is an optional reset and the function will just
 * return 0.
 */
int reset_control_assert(struct reset_control *rstc)
{
	if (!rstc)
		return 0;

	if (WARN_ON(IS_ERR(rstc)))
		return -EINVAL;

	if (reset_control_is_array(rstc))
		return reset_control_array_assert(rstc_to_array(rstc));

	if (rstc->shared) {
		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
			return -EINVAL;

		if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
			return -EINVAL;

		if (atomic_dec_return(&rstc->deassert_count) != 0)
			return 0;

		/*
		 * Shared reset controls allow the reset line to be in any state
		 * after this call, so doing nothing is a valid option.
		 */
		if (!rstc->rcdev->ops->assert)
			return 0;
	} else {
		/*
		 * If the reset controller does not implement .assert(), there
		 * is no way to guarantee that the reset line is asserted after
		 * this call.
		 */
		if (!rstc->rcdev->ops->assert)
			return -ENOTSUPP;

		if (!rstc->acquired) {
			WARN(1, "reset %s (ID: %u) is not acquired\n",
			     rcdev_name(rstc->rcdev), rstc->id);
			return -EPERM;
		}
	}

	return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
}
EXPORT_SYMBOL_GPL(reset_control_assert);

/**
 * reset_control_deassert - deasserts the reset line
 * @rstc: reset controller
 *
 * After calling this function, the reset is guaranteed to be deasserted.
 * Consumers must not use reset_control_reset on shared reset lines when
 * reset_control_(de)assert has been used.
 *
 * If rstc is NULL it is an optional reset and the function will just
 * return 0.
 */
int reset_control_deassert(struct reset_control *rstc)
{
	if (!rstc)
		return 0;

	if (WARN_ON(IS_ERR(rstc)))
		return -EINVAL;

	if (reset_control_is_array(rstc))
		return reset_control_array_deassert(rstc_to_array(rstc));

	if (rstc->shared) {
		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
			return -EINVAL;

		if (atomic_inc_return(&rstc->deassert_count) != 1)
			return 0;
	} else {
		if (!rstc->acquired) {
			WARN(1, "reset %s (ID: %u) is not acquired\n",
			     rcdev_name(rstc->rcdev), rstc->id);
			return -EPERM;
		}
	}

	/*
	 * If the reset controller does not implement .deassert(), we assume
	 * that it handles self-deasserting reset lines via .reset(). In that
	 * case, the reset lines are deasserted by default. If that is not the
	 * case, the reset controller driver should implement .deassert() and
	 * return -ENOTSUPP.
	 */
	if (!rstc->rcdev->ops->deassert)
		return 0;

	return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
}
EXPORT_SYMBOL_GPL(reset_control_deassert);

/**
 * reset_control_status - returns a negative errno if not supported, a
 * positive value if the reset line is asserted, or zero if the reset
 * line is not asserted or if the desc is NULL (optional reset).
 * @rstc: reset controller
 */
int reset_control_status(struct reset_control *rstc)
{
	if (!rstc)
		return 0;

	if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
		return -EINVAL;

	if (rstc->rcdev->ops->status)
		return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);

	return -ENOTSUPP;
}
EXPORT_SYMBOL_GPL(reset_control_status);

/**
 * reset_control_acquire() - acquires a reset control for exclusive use
 * @rstc: reset control
 *
 * This is used to explicitly acquire a reset control for exclusive use. Note
 * that exclusive resets are requested as acquired by default. In order for a
 * second consumer to be able to control the reset, the first consumer has to
 * release it first. Typically the easiest way to achieve this is to call the
 * reset_control_get_exclusive_released() to obtain an instance of the reset
 * control. Such reset controls are not acquired by default.
 *
 * Consumers implementing shared access to an exclusive reset need to follow
 * a specific protocol in order to work together. Before consumers can change
 * a reset they must acquire exclusive access using reset_control_acquire().
 * After they are done operating the reset, they must release exclusive access
 * with a call to reset_control_release(). Consumers are not granted exclusive
 * access to the reset as long as another consumer hasn't released a reset.
 *
 * See also: reset_control_release()
 */
int reset_control_acquire(struct reset_control *rstc)
{
	struct reset_control *rc;

	if (!rstc)
		return 0;

	if (WARN_ON(IS_ERR(rstc)))
		return -EINVAL;

	if (reset_control_is_array(rstc))
		return reset_control_array_acquire(rstc_to_array(rstc));

	mutex_lock(&reset_list_mutex);

	if (rstc->acquired) {
		mutex_unlock(&reset_list_mutex);
		return 0;
	}

	list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
		if (rstc != rc && rstc->id == rc->id) {
			if (rc->acquired) {
				mutex_unlock(&reset_list_mutex);
				return -EBUSY;
			}
		}
	}

	rstc->acquired = true;

	mutex_unlock(&reset_list_mutex);
	return 0;
}
EXPORT_SYMBOL_GPL(reset_control_acquire);

/**
 * reset_control_release() - releases exclusive access to a reset control
 * @rstc: reset control
 *
 * Releases exclusive access right to a reset control previously obtained by a
 * call to reset_control_acquire(). Until a consumer calls this function, no
 * other consumers will be granted exclusive access.
 *
 * See also: reset_control_acquire()
 */
void reset_control_release(struct reset_control *rstc)
{
	if (!rstc || WARN_ON(IS_ERR(rstc)))
		return;

	if (reset_control_is_array(rstc))
		reset_control_array_release(rstc_to_array(rstc));
	else
		rstc->acquired = false;
}
EXPORT_SYMBOL_GPL(reset_control_release);

static struct reset_control *__reset_control_get_internal(
				struct reset_controller_dev *rcdev,
				unsigned int index, bool shared, bool acquired)
{
	struct reset_control *rstc;

	lockdep_assert_held(&reset_list_mutex);

	list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
		if (rstc->id == index) {
			/*
			 * Allow creating a secondary exclusive reset_control
			 * that is initially not acquired for an already
			 * controlled reset line.
			 */
			if (!rstc->shared && !shared && !acquired)
				break;

			if (WARN_ON(!rstc->shared || !shared))
				return ERR_PTR(-EBUSY);

			kref_get(&rstc->refcnt);
			return rstc;
		}
	}

	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
	if (!rstc)
		return ERR_PTR(-ENOMEM);

	try_module_get(rcdev->owner);

	rstc->rcdev = rcdev;
	list_add(&rstc->list, &rcdev->reset_control_head);
	rstc->id = index;
	kref_init(&rstc->refcnt);
	rstc->acquired = acquired;
	rstc->shared = shared;

	return rstc;
}

static void __reset_control_release(struct kref *kref)
{
	struct reset_control *rstc = container_of(kref, struct reset_control,
						  refcnt);

	lockdep_assert_held(&reset_list_mutex);

	module_put(rstc->rcdev->owner);

	list_del(&rstc->list);
	kfree(rstc);
}

static void __reset_control_put_internal(struct reset_control *rstc)
{
	lockdep_assert_held(&reset_list_mutex);

	kref_put(&rstc->refcnt, __reset_control_release);
}

struct reset_control *__of_reset_control_get(struct device_node *node,
				     const char *id, int index, bool shared,
				     bool optional, bool acquired)
{
	struct reset_control *rstc;
	struct reset_controller_dev *r, *rcdev;
	struct of_phandle_args args;
	int rstc_id;
	int ret;

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

	if (id) {
		index = of_property_match_string(node,
						 "reset-names", id);
		if (index == -EILSEQ)
			return ERR_PTR(index);
		if (index < 0)
			return optional ? NULL : ERR_PTR(-ENOENT);
	}

	ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
					 index, &args);
	if (ret == -EINVAL)
		return ERR_PTR(ret);
	if (ret)
		return optional ? NULL : ERR_PTR(ret);

	mutex_lock(&reset_list_mutex);
	rcdev = NULL;
	list_for_each_entry(r, &reset_controller_list, list) {
		if (args.np == r->of_node) {
			rcdev = r;
			break;
		}
	}

	if (!rcdev) {
		rstc = ERR_PTR(-EPROBE_DEFER);
		goto out;
	}

	if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
		rstc = ERR_PTR(-EINVAL);
		goto out;
	}

	rstc_id = rcdev->of_xlate(rcdev, &args);
	if (rstc_id < 0) {
		rstc = ERR_PTR(rstc_id);
		goto out;
	}

	/* reset_list_mutex also protects the rcdev's reset_control list */
	rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);

out:
	mutex_unlock(&reset_list_mutex);
	of_node_put(args.np);

	return rstc;
}
EXPORT_SYMBOL_GPL(__of_reset_control_get);

static struct reset_controller_dev *
__reset_controller_by_name(const char *name)
{
	struct reset_controller_dev *rcdev;

	lockdep_assert_held(&reset_list_mutex);

	list_for_each_entry(rcdev, &reset_controller_list, list) {
		if (!rcdev->dev)
			continue;

		if (!strcmp(name, dev_name(rcdev->dev)))
			return rcdev;
	}

	return NULL;
}

static struct reset_control *
__reset_control_get_from_lookup(struct device *dev, const char *con_id,
				bool shared, bool optional, bool acquired)
{
	const struct reset_control_lookup *lookup;
	struct reset_controller_dev *rcdev;
	const char *dev_id = dev_name(dev);
	struct reset_control *rstc = NULL;

	mutex_lock(&reset_lookup_mutex);

	list_for_each_entry(lookup, &reset_lookup_list, list) {
		if (strcmp(lookup->dev_id, dev_id))
			continue;

		if ((!con_id && !lookup->con_id) ||
		    ((con_id && lookup->con_id) &&
		     !strcmp(con_id, lookup->con_id))) {
			mutex_lock(&reset_list_mutex);
			rcdev = __reset_controller_by_name(lookup->provider);
			if (!rcdev) {
				mutex_unlock(&reset_list_mutex);
				mutex_unlock(&reset_lookup_mutex);
				/* Reset provider may not be ready yet. */
				return ERR_PTR(-EPROBE_DEFER);
			}

			rstc = __reset_control_get_internal(rcdev,
							    lookup->index,
							    shared, acquired);
			mutex_unlock(&reset_list_mutex);
			break;
		}
	}

	mutex_unlock(&reset_lookup_mutex);

	if (!rstc)
		return optional ? NULL : ERR_PTR(-ENOENT);

	return rstc;
}

struct reset_control *__reset_control_get(struct device *dev, const char *id,
					  int index, bool shared, bool optional,
					  bool acquired)
{
	if (WARN_ON(shared && acquired))
		return ERR_PTR(-EINVAL);

	if (dev->of_node)
		return __of_reset_control_get(dev->of_node, id, index, shared,
					      optional, acquired);

	return __reset_control_get_from_lookup(dev, id, shared, optional,
					       acquired);
}
EXPORT_SYMBOL_GPL(__reset_control_get);

static void reset_control_array_put(struct reset_control_array *resets)
{
	int i;

	mutex_lock(&reset_list_mutex);
	for (i = 0; i < resets->num_rstcs; i++)
		__reset_control_put_internal(resets->rstc[i]);
	mutex_unlock(&reset_list_mutex);
	kfree(resets);
}

/**
 * reset_control_put - free the reset controller
 * @rstc: reset controller
 */
void reset_control_put(struct reset_control *rstc)
{
	if (IS_ERR_OR_NULL(rstc))
		return;

	if (reset_control_is_array(rstc)) {
		reset_control_array_put(rstc_to_array(rstc));
		return;
	}

	mutex_lock(&reset_list_mutex);
	__reset_control_put_internal(rstc);
	mutex_unlock(&reset_list_mutex);
}
EXPORT_SYMBOL_GPL(reset_control_put);

static void devm_reset_control_release(struct device *dev, void *res)
{
	reset_control_put(*(struct reset_control **)res);
}

struct reset_control *__devm_reset_control_get(struct device *dev,
				     const char *id, int index, bool shared,
				     bool optional, bool acquired)
{
	struct reset_control **ptr, *rstc;

	ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
			   GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
	if (!IS_ERR_OR_NULL(rstc)) {
		*ptr = rstc;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return rstc;
}
EXPORT_SYMBOL_GPL(__devm_reset_control_get);

/**
 * device_reset - find reset controller associated with the device
 *                and perform reset
 * @dev: device to be reset by the controller
 * @optional: whether it is optional to reset the device
 *
 * Convenience wrapper for __reset_control_get() and reset_control_reset().
 * This is useful for the common case of devices with single, dedicated reset
 * lines.
 */
int __device_reset(struct device *dev, bool optional)
{
	struct reset_control *rstc;
	int ret;

	rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
	if (IS_ERR(rstc))
		return PTR_ERR(rstc);

	ret = reset_control_reset(rstc);

	reset_control_put(rstc);

	return ret;
}
EXPORT_SYMBOL_GPL(__device_reset);

/*
 * APIs to manage an array of reset controls.
 */

/**
 * of_reset_control_get_count - Count number of resets available with a device
 *
 * @node: device node that contains 'resets'.
 *
 * Returns positive reset count on success, or error number on failure and
 * on count being zero.
 */
static int of_reset_control_get_count(struct device_node *node)
{
	int count;

	if (!node)
		return -EINVAL;

	count = of_count_phandle_with_args(node, "resets", "#reset-cells");
	if (count == 0)
		count = -ENOENT;

	return count;
}

/**
 * of_reset_control_array_get - Get a list of reset controls using
 *				device node.
 *
 * @np: device node for the device that requests the reset controls array
 * @shared: whether reset controls are shared or not
 * @optional: whether it is optional to get the reset controls
 * @acquired: only one reset control may be acquired for a given controller
 *            and ID
 *
 * Returns pointer to allocated reset_control on success or error on failure
 */
struct reset_control *
of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
			   bool acquired)
{
	struct reset_control_array *resets;
	struct reset_control *rstc;
	int num, i;

	num = of_reset_control_get_count(np);
	if (num < 0)
		return optional ? NULL : ERR_PTR(num);

	resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
	if (!resets)
		return ERR_PTR(-ENOMEM);

	for (i = 0; i < num; i++) {
		rstc = __of_reset_control_get(np, NULL, i, shared, optional,
					      acquired);
		if (IS_ERR(rstc))
			goto err_rst;
		resets->rstc[i] = rstc;
	}
	resets->num_rstcs = num;
	resets->base.array = true;

	return &resets->base;

err_rst:
	mutex_lock(&reset_list_mutex);
	while (--i >= 0)
		__reset_control_put_internal(resets->rstc[i]);
	mutex_unlock(&reset_list_mutex);

	kfree(resets);

	return rstc;
}
EXPORT_SYMBOL_GPL(of_reset_control_array_get);

/**
 * devm_reset_control_array_get - Resource managed reset control array get
 *
 * @dev: device that requests the list of reset controls
 * @shared: whether reset controls are shared or not
 * @optional: whether it is optional to get the reset controls
 *
 * The reset control array APIs are intended for a list of resets
 * that just have to be asserted or deasserted, without any
 * requirements on the order.
 *
 * Returns pointer to allocated reset_control on success or error on failure
 */
struct reset_control *
devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
{
	struct reset_control **devres;
	struct reset_control *rstc;

	devres = devres_alloc(devm_reset_control_release, sizeof(*devres),
			      GFP_KERNEL);
	if (!devres)
		return ERR_PTR(-ENOMEM);

	rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
	if (IS_ERR_OR_NULL(rstc)) {
		devres_free(devres);
		return rstc;
	}

	*devres = rstc;
	devres_add(dev, devres);

	return rstc;
}
EXPORT_SYMBOL_GPL(devm_reset_control_array_get);

static int reset_control_get_count_from_lookup(struct device *dev)
{
	const struct reset_control_lookup *lookup;
	const char *dev_id;
	int count = 0;

	if (!dev)
		return -EINVAL;

	dev_id = dev_name(dev);
	mutex_lock(&reset_lookup_mutex);

	list_for_each_entry(lookup, &reset_lookup_list, list) {
		if (!strcmp(lookup->dev_id, dev_id))
			count++;
	}

	mutex_unlock(&reset_lookup_mutex);

	if (count == 0)
		count = -ENOENT;

	return count;
}

/**
 * reset_control_get_count - Count number of resets available with a device
 *
 * @dev: device for which to return the number of resets
 *
 * Returns positive reset count on success, or error number on failure and
 * on count being zero.
 */
int reset_control_get_count(struct device *dev)
{
	if (dev->of_node)
		return of_reset_control_get_count(dev->of_node);

	return reset_control_get_count_from_lookup(dev);
}
EXPORT_SYMBOL_GPL(reset_control_get_count);