1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Reset Controller framework
  4 *
  5 * Copyright 2013 Philipp Zabel, Pengutronix
  6 */
  7#include <linux/atomic.h>
  8#include <linux/device.h>
  9#include <linux/err.h>
 10#include <linux/export.h>
 11#include <linux/kernel.h>
 12#include <linux/kref.h>
 13#include <linux/module.h>
 14#include <linux/of.h>
 15#include <linux/reset.h>
 16#include <linux/reset-controller.h>
 17#include <linux/slab.h>
 18
 19static DEFINE_MUTEX(reset_list_mutex);
 20static LIST_HEAD(reset_controller_list);
 21
 22static DEFINE_MUTEX(reset_lookup_mutex);
 23static LIST_HEAD(reset_lookup_list);
 24
 25/**
 26 * struct reset_control - a reset control
 27 * @rcdev: a pointer to the reset controller device
 28 *         this reset control belongs to
 29 * @list: list entry for the rcdev's reset controller list
 30 * @id: ID of the reset controller in the reset
 31 *      controller device
 32 * @refcnt: Number of gets of this reset_control
 33 * @acquired: Only one reset_control may be acquired for a given rcdev and id.
 34 * @shared: Is this a shared (1), or an exclusive (0) reset_control?
 35 * @deassert_cnt: Number of times this reset line has been deasserted
 36 * @triggered_count: Number of times this reset line has been reset. Currently
 37 *                   only used for shared resets, which means that the value
 38 *                   will be either 0 or 1.
 39 */
 40struct reset_control {
 41	struct reset_controller_dev *rcdev;
 42	struct list_head list;
 43	unsigned int id;
 44	struct kref refcnt;
 45	bool acquired;
 46	bool shared;
 47	bool array;
 48	atomic_t deassert_count;
 49	atomic_t triggered_count;
 50};
 51
 52/**
 53 * struct reset_control_array - an array of reset controls
 54 * @base: reset control for compatibility with reset control API functions
 55 * @num_rstcs: number of reset controls
 56 * @rstc: array of reset controls
 57 */
 58struct reset_control_array {
 59	struct reset_control base;
 60	unsigned int num_rstcs;
 61	struct reset_control *rstc[];
 62};
 63
 64static const char *rcdev_name(struct reset_controller_dev *rcdev)
 65{
 66	if (rcdev->dev)
 67		return dev_name(rcdev->dev);
 68
 69	if (rcdev->of_node)
 70		return rcdev->of_node->full_name;
 71
 72	return NULL;
 73}
 74
 75/**
 76 * of_reset_simple_xlate - translate reset_spec to the reset line number
 77 * @rcdev: a pointer to the reset controller device
 78 * @reset_spec: reset line specifier as found in the device tree
 79 *
 80 * This static translation function is used by default if of_xlate in
 81 * :c:type:`reset_controller_dev` is not set. It is useful for all reset
 82 * controllers with 1:1 mapping, where reset lines can be indexed by number
 83 * without gaps.
 84 */
 85static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
 86			  const struct of_phandle_args *reset_spec)
 87{
 88	if (reset_spec->args[0] >= rcdev->nr_resets)
 89		return -EINVAL;
 90
 91	return reset_spec->args[0];
 92}
 93
 94/**
 95 * reset_controller_register - register a reset controller device
 96 * @rcdev: a pointer to the initialized reset controller device
 97 */
 98int reset_controller_register(struct reset_controller_dev *rcdev)
 99{
100	if (!rcdev->of_xlate) {
101		rcdev->of_reset_n_cells = 1;
102		rcdev->of_xlate = of_reset_simple_xlate;
103	}
104
105	INIT_LIST_HEAD(&rcdev->reset_control_head);
106
107	mutex_lock(&reset_list_mutex);
108	list_add(&rcdev->list, &reset_controller_list);
109	mutex_unlock(&reset_list_mutex);
110
111	return 0;
112}
113EXPORT_SYMBOL_GPL(reset_controller_register);
114
115/**
116 * reset_controller_unregister - unregister a reset controller device
117 * @rcdev: a pointer to the reset controller device
118 */
119void reset_controller_unregister(struct reset_controller_dev *rcdev)
120{
121	mutex_lock(&reset_list_mutex);
122	list_del(&rcdev->list);
123	mutex_unlock(&reset_list_mutex);
124}
125EXPORT_SYMBOL_GPL(reset_controller_unregister);
126
127static void devm_reset_controller_release(struct device *dev, void *res)
128{
129	reset_controller_unregister(*(struct reset_controller_dev **)res);
130}
131
132/**
133 * devm_reset_controller_register - resource managed reset_controller_register()
134 * @dev: device that is registering this reset controller
135 * @rcdev: a pointer to the initialized reset controller device
136 *
137 * Managed reset_controller_register(). For reset controllers registered by
138 * this function, reset_controller_unregister() is automatically called on
139 * driver detach. See reset_controller_register() for more information.
140 */
141int devm_reset_controller_register(struct device *dev,
142				   struct reset_controller_dev *rcdev)
143{
144	struct reset_controller_dev **rcdevp;
145	int ret;
146
147	rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
148			      GFP_KERNEL);
149	if (!rcdevp)
150		return -ENOMEM;
151
152	ret = reset_controller_register(rcdev);
153	if (ret) {
154		devres_free(rcdevp);
155		return ret;
156	}
157
158	*rcdevp = rcdev;
159	devres_add(dev, rcdevp);
160
161	return ret;
162}
163EXPORT_SYMBOL_GPL(devm_reset_controller_register);
164
165/**
166 * reset_controller_add_lookup - register a set of lookup entries
167 * @lookup: array of reset lookup entries
168 * @num_entries: number of entries in the lookup array
169 */
170void reset_controller_add_lookup(struct reset_control_lookup *lookup,
171				 unsigned int num_entries)
172{
173	struct reset_control_lookup *entry;
174	unsigned int i;
175
176	mutex_lock(&reset_lookup_mutex);
177	for (i = 0; i < num_entries; i++) {
178		entry = &lookup[i];
179
180		if (!entry->dev_id || !entry->provider) {
181			pr_warn("%s(): reset lookup entry badly specified, skipping\n",
182				__func__);
183			continue;
184		}
185
186		list_add_tail(&entry->list, &reset_lookup_list);
187	}
188	mutex_unlock(&reset_lookup_mutex);
189}
190EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
191
192static inline struct reset_control_array *
193rstc_to_array(struct reset_control *rstc) {
194	return container_of(rstc, struct reset_control_array, base);
195}
196
197static int reset_control_array_reset(struct reset_control_array *resets)
198{
199	int ret, i;
200
201	for (i = 0; i < resets->num_rstcs; i++) {
202		ret = reset_control_reset(resets->rstc[i]);
203		if (ret)
204			return ret;
205	}
206
207	return 0;
208}
209
210static int reset_control_array_assert(struct reset_control_array *resets)
211{
212	int ret, i;
213
214	for (i = 0; i < resets->num_rstcs; i++) {
215		ret = reset_control_assert(resets->rstc[i]);
216		if (ret)
217			goto err;
218	}
219
220	return 0;
221
222err:
223	while (i--)
224		reset_control_deassert(resets->rstc[i]);
225	return ret;
226}
227
228static int reset_control_array_deassert(struct reset_control_array *resets)
229{
230	int ret, i;
231
232	for (i = 0; i < resets->num_rstcs; i++) {
233		ret = reset_control_deassert(resets->rstc[i]);
234		if (ret)
235			goto err;
236	}
237
238	return 0;
239
240err:
241	while (i--)
242		reset_control_assert(resets->rstc[i]);
243	return ret;
244}
245
246static int reset_control_array_acquire(struct reset_control_array *resets)
247{
248	unsigned int i;
249	int err;
250
251	for (i = 0; i < resets->num_rstcs; i++) {
252		err = reset_control_acquire(resets->rstc[i]);
253		if (err < 0)
254			goto release;
255	}
256
257	return 0;
258
259release:
260	while (i--)
261		reset_control_release(resets->rstc[i]);
262
263	return err;
264}
265
266static void reset_control_array_release(struct reset_control_array *resets)
267{
268	unsigned int i;
269
270	for (i = 0; i < resets->num_rstcs; i++)
271		reset_control_release(resets->rstc[i]);
272}
273
274static inline bool reset_control_is_array(struct reset_control *rstc)
275{
276	return rstc->array;
277}
278
279/**
280 * reset_control_reset - reset the controlled device
281 * @rstc: reset controller
282 *
283 * On a shared reset line the actual reset pulse is only triggered once for the
284 * lifetime of the reset_control instance: for all but the first caller this is
285 * a no-op.
286 * Consumers must not use reset_control_(de)assert on shared reset lines when
287 * reset_control_reset has been used.
288 *
289 * If rstc is NULL it is an optional reset and the function will just
290 * return 0.
291 */
292int reset_control_reset(struct reset_control *rstc)
293{
294	int ret;
295
296	if (!rstc)
297		return 0;
298
299	if (WARN_ON(IS_ERR(rstc)))
300		return -EINVAL;
301
302	if (reset_control_is_array(rstc))
303		return reset_control_array_reset(rstc_to_array(rstc));
304
305	if (!rstc->rcdev->ops->reset)
306		return -ENOTSUPP;
307
308	if (rstc->shared) {
309		if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
310			return -EINVAL;
311
312		if (atomic_inc_return(&rstc->triggered_count) != 1)
313			return 0;
314	} else {
315		if (!rstc->acquired)
316			return -EPERM;
317	}
318
319	ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
320	if (rstc->shared && ret)
321		atomic_dec(&rstc->triggered_count);
322
323	return ret;
324}
325EXPORT_SYMBOL_GPL(reset_control_reset);
326
327/**
328 * reset_control_assert - asserts the reset line
329 * @rstc: reset controller
330 *
331 * Calling this on an exclusive reset controller guarantees that the reset
332 * will be asserted. When called on a shared reset controller the line may
333 * still be deasserted, as long as other users keep it so.
334 *
335 * For shared reset controls a driver cannot expect the hw's registers and
336 * internal state to be reset, but must be prepared for this to happen.
337 * Consumers must not use reset_control_reset on shared reset lines when
338 * reset_control_(de)assert has been used.
339 *
340 * If rstc is NULL it is an optional reset and the function will just
341 * return 0.
342 */
343int reset_control_assert(struct reset_control *rstc)
344{
345	if (!rstc)
346		return 0;
347
348	if (WARN_ON(IS_ERR(rstc)))
349		return -EINVAL;
350
351	if (reset_control_is_array(rstc))
352		return reset_control_array_assert(rstc_to_array(rstc));
353
354	if (rstc->shared) {
355		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
356			return -EINVAL;
357
358		if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
359			return -EINVAL;
360
361		if (atomic_dec_return(&rstc->deassert_count) != 0)
362			return 0;
363
364		/*
365		 * Shared reset controls allow the reset line to be in any state
366		 * after this call, so doing nothing is a valid option.
367		 */
368		if (!rstc->rcdev->ops->assert)
369			return 0;
370	} else {
371		/*
372		 * If the reset controller does not implement .assert(), there
373		 * is no way to guarantee that the reset line is asserted after
374		 * this call.
375		 */
376		if (!rstc->rcdev->ops->assert)
377			return -ENOTSUPP;
378
379		if (!rstc->acquired) {
380			WARN(1, "reset %s (ID: %u) is not acquired\n",
381			     rcdev_name(rstc->rcdev), rstc->id);
382			return -EPERM;
383		}
384	}
385
386	return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
387}
388EXPORT_SYMBOL_GPL(reset_control_assert);
389
390/**
391 * reset_control_deassert - deasserts the reset line
392 * @rstc: reset controller
393 *
394 * After calling this function, the reset is guaranteed to be deasserted.
395 * Consumers must not use reset_control_reset on shared reset lines when
396 * reset_control_(de)assert has been used.
397 *
398 * If rstc is NULL it is an optional reset and the function will just
399 * return 0.
400 */
401int reset_control_deassert(struct reset_control *rstc)
402{
403	if (!rstc)
404		return 0;
405
406	if (WARN_ON(IS_ERR(rstc)))
407		return -EINVAL;
408
409	if (reset_control_is_array(rstc))
410		return reset_control_array_deassert(rstc_to_array(rstc));
411
412	if (rstc->shared) {
413		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
414			return -EINVAL;
415
416		if (atomic_inc_return(&rstc->deassert_count) != 1)
417			return 0;
418	} else {
419		if (!rstc->acquired) {
420			WARN(1, "reset %s (ID: %u) is not acquired\n",
421			     rcdev_name(rstc->rcdev), rstc->id);
422			return -EPERM;
423		}
424	}
425
426	/*
427	 * If the reset controller does not implement .deassert(), we assume
428	 * that it handles self-deasserting reset lines via .reset(). In that
429	 * case, the reset lines are deasserted by default. If that is not the
430	 * case, the reset controller driver should implement .deassert() and
431	 * return -ENOTSUPP.
432	 */
433	if (!rstc->rcdev->ops->deassert)
434		return 0;
435
436	return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
437}
438EXPORT_SYMBOL_GPL(reset_control_deassert);
439
440/**
441 * reset_control_status - returns a negative errno if not supported, a
442 * positive value if the reset line is asserted, or zero if the reset
443 * line is not asserted or if the desc is NULL (optional reset).
444 * @rstc: reset controller
445 */
446int reset_control_status(struct reset_control *rstc)
447{
448	if (!rstc)
449		return 0;
450
451	if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
452		return -EINVAL;
453
454	if (rstc->rcdev->ops->status)
455		return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
456
457	return -ENOTSUPP;
458}
459EXPORT_SYMBOL_GPL(reset_control_status);
460
461/**
462 * reset_control_acquire() - acquires a reset control for exclusive use
463 * @rstc: reset control
464 *
465 * This is used to explicitly acquire a reset control for exclusive use. Note
466 * that exclusive resets are requested as acquired by default. In order for a
467 * second consumer to be able to control the reset, the first consumer has to
468 * release it first. Typically the easiest way to achieve this is to call the
469 * reset_control_get_exclusive_released() to obtain an instance of the reset
470 * control. Such reset controls are not acquired by default.
471 *
472 * Consumers implementing shared access to an exclusive reset need to follow
473 * a specific protocol in order to work together. Before consumers can change
474 * a reset they must acquire exclusive access using reset_control_acquire().
475 * After they are done operating the reset, they must release exclusive access
476 * with a call to reset_control_release(). Consumers are not granted exclusive
477 * access to the reset as long as another consumer hasn't released a reset.
478 *
479 * See also: reset_control_release()
480 */
481int reset_control_acquire(struct reset_control *rstc)
482{
483	struct reset_control *rc;
484
485	if (!rstc)
486		return 0;
487
488	if (WARN_ON(IS_ERR(rstc)))
489		return -EINVAL;
490
491	if (reset_control_is_array(rstc))
492		return reset_control_array_acquire(rstc_to_array(rstc));
493
494	mutex_lock(&reset_list_mutex);
495
496	if (rstc->acquired) {
497		mutex_unlock(&reset_list_mutex);
498		return 0;
499	}
500
501	list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
502		if (rstc != rc && rstc->id == rc->id) {
503			if (rc->acquired) {
504				mutex_unlock(&reset_list_mutex);
505				return -EBUSY;
506			}
507		}
508	}
509
510	rstc->acquired = true;
511
512	mutex_unlock(&reset_list_mutex);
513	return 0;
514}
515EXPORT_SYMBOL_GPL(reset_control_acquire);
516
517/**
518 * reset_control_release() - releases exclusive access to a reset control
519 * @rstc: reset control
520 *
521 * Releases exclusive access right to a reset control previously obtained by a
522 * call to reset_control_acquire(). Until a consumer calls this function, no
523 * other consumers will be granted exclusive access.
524 *
525 * See also: reset_control_acquire()
526 */
527void reset_control_release(struct reset_control *rstc)
528{
529	if (!rstc || WARN_ON(IS_ERR(rstc)))
530		return;
531
532	if (reset_control_is_array(rstc))
533		reset_control_array_release(rstc_to_array(rstc));
534	else
535		rstc->acquired = false;
536}
537EXPORT_SYMBOL_GPL(reset_control_release);
538
539static struct reset_control *__reset_control_get_internal(
540				struct reset_controller_dev *rcdev,
541				unsigned int index, bool shared, bool acquired)
542{
543	struct reset_control *rstc;
544
545	lockdep_assert_held(&reset_list_mutex);
546
547	list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
548		if (rstc->id == index) {
549			/*
550			 * Allow creating a secondary exclusive reset_control
551			 * that is initially not acquired for an already
552			 * controlled reset line.
553			 */
554			if (!rstc->shared && !shared && !acquired)
555				break;
556
557			if (WARN_ON(!rstc->shared || !shared))
558				return ERR_PTR(-EBUSY);
559
560			kref_get(&rstc->refcnt);
561			return rstc;
562		}
563	}
564
565	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
566	if (!rstc)
567		return ERR_PTR(-ENOMEM);
568
569	try_module_get(rcdev->owner);
570
571	rstc->rcdev = rcdev;
572	list_add(&rstc->list, &rcdev->reset_control_head);
573	rstc->id = index;
574	kref_init(&rstc->refcnt);
575	rstc->acquired = acquired;
576	rstc->shared = shared;
577
578	return rstc;
579}
580
581static void __reset_control_release(struct kref *kref)
582{
583	struct reset_control *rstc = container_of(kref, struct reset_control,
584						  refcnt);
585
586	lockdep_assert_held(&reset_list_mutex);
587
588	module_put(rstc->rcdev->owner);
589
590	list_del(&rstc->list);
591	kfree(rstc);
592}
593
594static void __reset_control_put_internal(struct reset_control *rstc)
595{
596	lockdep_assert_held(&reset_list_mutex);
597
598	kref_put(&rstc->refcnt, __reset_control_release);
599}
600
601struct reset_control *__of_reset_control_get(struct device_node *node,
602				     const char *id, int index, bool shared,
603				     bool optional, bool acquired)
604{
605	struct reset_control *rstc;
606	struct reset_controller_dev *r, *rcdev;
607	struct of_phandle_args args;
608	int rstc_id;
609	int ret;
610
611	if (!node)
612		return ERR_PTR(-EINVAL);
613
614	if (id) {
615		index = of_property_match_string(node,
616						 "reset-names", id);
617		if (index == -EILSEQ)
618			return ERR_PTR(index);
619		if (index < 0)
620			return optional ? NULL : ERR_PTR(-ENOENT);
621	}
622
623	ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
624					 index, &args);
625	if (ret == -EINVAL)
626		return ERR_PTR(ret);
627	if (ret)
628		return optional ? NULL : ERR_PTR(ret);
629
630	mutex_lock(&reset_list_mutex);
631	rcdev = NULL;
632	list_for_each_entry(r, &reset_controller_list, list) {
633		if (args.np == r->of_node) {
634			rcdev = r;
635			break;
636		}
637	}
638
639	if (!rcdev) {
640		rstc = ERR_PTR(-EPROBE_DEFER);
641		goto out;
642	}
643
644	if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
645		rstc = ERR_PTR(-EINVAL);
646		goto out;
647	}
648
649	rstc_id = rcdev->of_xlate(rcdev, &args);
650	if (rstc_id < 0) {
651		rstc = ERR_PTR(rstc_id);
652		goto out;
653	}
654
655	/* reset_list_mutex also protects the rcdev's reset_control list */
656	rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
657
658out:
659	mutex_unlock(&reset_list_mutex);
660	of_node_put(args.np);
661
662	return rstc;
663}
664EXPORT_SYMBOL_GPL(__of_reset_control_get);
665
666static struct reset_controller_dev *
667__reset_controller_by_name(const char *name)
668{
669	struct reset_controller_dev *rcdev;
670
671	lockdep_assert_held(&reset_list_mutex);
672
673	list_for_each_entry(rcdev, &reset_controller_list, list) {
674		if (!rcdev->dev)
675			continue;
676
677		if (!strcmp(name, dev_name(rcdev->dev)))
678			return rcdev;
679	}
680
681	return NULL;
682}
683
684static struct reset_control *
685__reset_control_get_from_lookup(struct device *dev, const char *con_id,
686				bool shared, bool optional, bool acquired)
687{
688	const struct reset_control_lookup *lookup;
689	struct reset_controller_dev *rcdev;
690	const char *dev_id = dev_name(dev);
691	struct reset_control *rstc = NULL;
692
693	mutex_lock(&reset_lookup_mutex);
694
695	list_for_each_entry(lookup, &reset_lookup_list, list) {
696		if (strcmp(lookup->dev_id, dev_id))
697			continue;
698
699		if ((!con_id && !lookup->con_id) ||
700		    ((con_id && lookup->con_id) &&
701		     !strcmp(con_id, lookup->con_id))) {
702			mutex_lock(&reset_list_mutex);
703			rcdev = __reset_controller_by_name(lookup->provider);
704			if (!rcdev) {
705				mutex_unlock(&reset_list_mutex);
706				mutex_unlock(&reset_lookup_mutex);
707				/* Reset provider may not be ready yet. */
708				return ERR_PTR(-EPROBE_DEFER);
709			}
710
711			rstc = __reset_control_get_internal(rcdev,
712							    lookup->index,
713							    shared, acquired);
714			mutex_unlock(&reset_list_mutex);
715			break;
716		}
717	}
718
719	mutex_unlock(&reset_lookup_mutex);
720
721	if (!rstc)
722		return optional ? NULL : ERR_PTR(-ENOENT);
723
724	return rstc;
725}
726
727struct reset_control *__reset_control_get(struct device *dev, const char *id,
728					  int index, bool shared, bool optional,
729					  bool acquired)
730{
731	if (WARN_ON(shared && acquired))
732		return ERR_PTR(-EINVAL);
733
734	if (dev->of_node)
735		return __of_reset_control_get(dev->of_node, id, index, shared,
736					      optional, acquired);
737
738	return __reset_control_get_from_lookup(dev, id, shared, optional,
739					       acquired);
740}
741EXPORT_SYMBOL_GPL(__reset_control_get);
742
743static void reset_control_array_put(struct reset_control_array *resets)
744{
745	int i;
746
747	mutex_lock(&reset_list_mutex);
748	for (i = 0; i < resets->num_rstcs; i++)
749		__reset_control_put_internal(resets->rstc[i]);
750	mutex_unlock(&reset_list_mutex);
751	kfree(resets);
752}
753
754/**
755 * reset_control_put - free the reset controller
756 * @rstc: reset controller
757 */
758void reset_control_put(struct reset_control *rstc)
759{
760	if (IS_ERR_OR_NULL(rstc))
761		return;
762
763	if (reset_control_is_array(rstc)) {
764		reset_control_array_put(rstc_to_array(rstc));
765		return;
766	}
767
768	mutex_lock(&reset_list_mutex);
769	__reset_control_put_internal(rstc);
770	mutex_unlock(&reset_list_mutex);
771}
772EXPORT_SYMBOL_GPL(reset_control_put);
773
774static void devm_reset_control_release(struct device *dev, void *res)
775{
776	reset_control_put(*(struct reset_control **)res);
777}
778
779struct reset_control *__devm_reset_control_get(struct device *dev,
780				     const char *id, int index, bool shared,
781				     bool optional, bool acquired)
782{
783	struct reset_control **ptr, *rstc;
784
785	ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
786			   GFP_KERNEL);
787	if (!ptr)
788		return ERR_PTR(-ENOMEM);
789
790	rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
791	if (IS_ERR_OR_NULL(rstc)) {
792		devres_free(ptr);
793		return rstc;
794	}
795
796	*ptr = rstc;
797	devres_add(dev, ptr);
798
799	return rstc;
800}
801EXPORT_SYMBOL_GPL(__devm_reset_control_get);
802
803/**
804 * device_reset - find reset controller associated with the device
805 *                and perform reset
806 * @dev: device to be reset by the controller
807 * @optional: whether it is optional to reset the device
808 *
809 * Convenience wrapper for __reset_control_get() and reset_control_reset().
810 * This is useful for the common case of devices with single, dedicated reset
811 * lines.
812 */
813int __device_reset(struct device *dev, bool optional)
814{
815	struct reset_control *rstc;
816	int ret;
817
818	rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
819	if (IS_ERR(rstc))
820		return PTR_ERR(rstc);
821
822	ret = reset_control_reset(rstc);
823
824	reset_control_put(rstc);
825
826	return ret;
827}
828EXPORT_SYMBOL_GPL(__device_reset);
829
830/*
831 * APIs to manage an array of reset controls.
832 */
833
834/**
835 * of_reset_control_get_count - Count number of resets available with a device
836 *
837 * @node: device node that contains 'resets'.
838 *
839 * Returns positive reset count on success, or error number on failure and
840 * on count being zero.
841 */
842static int of_reset_control_get_count(struct device_node *node)
843{
844	int count;
845
846	if (!node)
847		return -EINVAL;
848
849	count = of_count_phandle_with_args(node, "resets", "#reset-cells");
850	if (count == 0)
851		count = -ENOENT;
852
853	return count;
854}
855
856/**
857 * of_reset_control_array_get - Get a list of reset controls using
858 *				device node.
859 *
860 * @np: device node for the device that requests the reset controls array
861 * @shared: whether reset controls are shared or not
862 * @optional: whether it is optional to get the reset controls
863 * @acquired: only one reset control may be acquired for a given controller
864 *            and ID
865 *
866 * Returns pointer to allocated reset_control on success or error on failure
867 */
868struct reset_control *
869of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
870			   bool acquired)
871{
872	struct reset_control_array *resets;
873	struct reset_control *rstc;
874	int num, i;
875
876	num = of_reset_control_get_count(np);
877	if (num < 0)
878		return optional ? NULL : ERR_PTR(num);
879
880	resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
881	if (!resets)
882		return ERR_PTR(-ENOMEM);
883
884	for (i = 0; i < num; i++) {
885		rstc = __of_reset_control_get(np, NULL, i, shared, optional,
886					      acquired);
887		if (IS_ERR(rstc))
888			goto err_rst;
889		resets->rstc[i] = rstc;
890	}
891	resets->num_rstcs = num;
892	resets->base.array = true;
893
894	return &resets->base;
895
896err_rst:
897	mutex_lock(&reset_list_mutex);
898	while (--i >= 0)
899		__reset_control_put_internal(resets->rstc[i]);
900	mutex_unlock(&reset_list_mutex);
901
902	kfree(resets);
903
904	return rstc;
905}
906EXPORT_SYMBOL_GPL(of_reset_control_array_get);
907
908/**
909 * devm_reset_control_array_get - Resource managed reset control array get
910 *
911 * @dev: device that requests the list of reset controls
912 * @shared: whether reset controls are shared or not
913 * @optional: whether it is optional to get the reset controls
914 *
915 * The reset control array APIs are intended for a list of resets
916 * that just have to be asserted or deasserted, without any
917 * requirements on the order.
918 *
919 * Returns pointer to allocated reset_control on success or error on failure
920 */
921struct reset_control *
922devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
923{
924	struct reset_control **ptr, *rstc;
925
926	ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
927			   GFP_KERNEL);
928	if (!ptr)
929		return ERR_PTR(-ENOMEM);
930
931	rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
932	if (IS_ERR_OR_NULL(rstc)) {
933		devres_free(ptr);
934		return rstc;
935	}
936
937	*ptr = rstc;
938	devres_add(dev, ptr);
939
940	return rstc;
941}
942EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
943
944static int reset_control_get_count_from_lookup(struct device *dev)
945{
946	const struct reset_control_lookup *lookup;
947	const char *dev_id;
948	int count = 0;
949
950	if (!dev)
951		return -EINVAL;
952
953	dev_id = dev_name(dev);
954	mutex_lock(&reset_lookup_mutex);
955
956	list_for_each_entry(lookup, &reset_lookup_list, list) {
957		if (!strcmp(lookup->dev_id, dev_id))
958			count++;
959	}
960
961	mutex_unlock(&reset_lookup_mutex);
962
963	if (count == 0)
964		count = -ENOENT;
965
966	return count;
967}
968
969/**
970 * reset_control_get_count - Count number of resets available with a device
971 *
972 * @dev: device for which to return the number of resets
973 *
974 * Returns positive reset count on success, or error number on failure and
975 * on count being zero.
976 */
977int reset_control_get_count(struct device *dev)
978{
979	if (dev->of_node)
980		return of_reset_control_get_count(dev->of_node);
981
982	return reset_control_get_count_from_lookup(dev);
983}
984EXPORT_SYMBOL_GPL(reset_control_get_count);