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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);
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/acpi.h>
16#include <linux/reset.h>
17#include <linux/reset-controller.h>
18#include <linux/slab.h>
19
20static DEFINE_MUTEX(reset_list_mutex);
21static LIST_HEAD(reset_controller_list);
22
23static DEFINE_MUTEX(reset_lookup_mutex);
24static LIST_HEAD(reset_lookup_list);
25
26/**
27 * struct reset_control - a reset control
28 * @rcdev: a pointer to the reset controller device
29 * this reset control belongs to
30 * @list: list entry for the rcdev's reset controller list
31 * @id: ID of the reset controller in the reset
32 * controller device
33 * @refcnt: Number of gets of this reset_control
34 * @acquired: Only one reset_control may be acquired for a given rcdev and id.
35 * @shared: Is this a shared (1), or an exclusive (0) reset_control?
36 * @array: Is this an array of reset controls (1)?
37 * @deassert_count: Number of times this reset line has been deasserted
38 * @triggered_count: Number of times this reset line has been reset. Currently
39 * only used for shared resets, which means that the value
40 * will be either 0 or 1.
41 */
42struct reset_control {
43 struct reset_controller_dev *rcdev;
44 struct list_head list;
45 unsigned int id;
46 struct kref refcnt;
47 bool acquired;
48 bool shared;
49 bool array;
50 atomic_t deassert_count;
51 atomic_t triggered_count;
52};
53
54/**
55 * struct reset_control_array - an array of reset controls
56 * @base: reset control for compatibility with reset control API functions
57 * @num_rstcs: number of reset controls
58 * @rstc: array of reset controls
59 */
60struct reset_control_array {
61 struct reset_control base;
62 unsigned int num_rstcs;
63 struct reset_control *rstc[];
64};
65
66static const char *rcdev_name(struct reset_controller_dev *rcdev)
67{
68 if (rcdev->dev)
69 return dev_name(rcdev->dev);
70
71 if (rcdev->of_node)
72 return rcdev->of_node->full_name;
73
74 return NULL;
75}
76
77/**
78 * of_reset_simple_xlate - translate reset_spec to the reset line number
79 * @rcdev: a pointer to the reset controller device
80 * @reset_spec: reset line specifier as found in the device tree
81 *
82 * This static translation function is used by default if of_xlate in
83 * :c:type:`reset_controller_dev` is not set. It is useful for all reset
84 * controllers with 1:1 mapping, where reset lines can be indexed by number
85 * without gaps.
86 */
87static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
88 const struct of_phandle_args *reset_spec)
89{
90 if (reset_spec->args[0] >= rcdev->nr_resets)
91 return -EINVAL;
92
93 return reset_spec->args[0];
94}
95
96/**
97 * reset_controller_register - register a reset controller device
98 * @rcdev: a pointer to the initialized reset controller device
99 */
100int reset_controller_register(struct reset_controller_dev *rcdev)
101{
102 if (!rcdev->of_xlate) {
103 rcdev->of_reset_n_cells = 1;
104 rcdev->of_xlate = of_reset_simple_xlate;
105 }
106
107 INIT_LIST_HEAD(&rcdev->reset_control_head);
108
109 mutex_lock(&reset_list_mutex);
110 list_add(&rcdev->list, &reset_controller_list);
111 mutex_unlock(&reset_list_mutex);
112
113 return 0;
114}
115EXPORT_SYMBOL_GPL(reset_controller_register);
116
117/**
118 * reset_controller_unregister - unregister a reset controller device
119 * @rcdev: a pointer to the reset controller device
120 */
121void reset_controller_unregister(struct reset_controller_dev *rcdev)
122{
123 mutex_lock(&reset_list_mutex);
124 list_del(&rcdev->list);
125 mutex_unlock(&reset_list_mutex);
126}
127EXPORT_SYMBOL_GPL(reset_controller_unregister);
128
129static void devm_reset_controller_release(struct device *dev, void *res)
130{
131 reset_controller_unregister(*(struct reset_controller_dev **)res);
132}
133
134/**
135 * devm_reset_controller_register - resource managed reset_controller_register()
136 * @dev: device that is registering this reset controller
137 * @rcdev: a pointer to the initialized reset controller device
138 *
139 * Managed reset_controller_register(). For reset controllers registered by
140 * this function, reset_controller_unregister() is automatically called on
141 * driver detach. See reset_controller_register() for more information.
142 */
143int devm_reset_controller_register(struct device *dev,
144 struct reset_controller_dev *rcdev)
145{
146 struct reset_controller_dev **rcdevp;
147 int ret;
148
149 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
150 GFP_KERNEL);
151 if (!rcdevp)
152 return -ENOMEM;
153
154 ret = reset_controller_register(rcdev);
155 if (ret) {
156 devres_free(rcdevp);
157 return ret;
158 }
159
160 *rcdevp = rcdev;
161 devres_add(dev, rcdevp);
162
163 return ret;
164}
165EXPORT_SYMBOL_GPL(devm_reset_controller_register);
166
167/**
168 * reset_controller_add_lookup - register a set of lookup entries
169 * @lookup: array of reset lookup entries
170 * @num_entries: number of entries in the lookup array
171 */
172void reset_controller_add_lookup(struct reset_control_lookup *lookup,
173 unsigned int num_entries)
174{
175 struct reset_control_lookup *entry;
176 unsigned int i;
177
178 mutex_lock(&reset_lookup_mutex);
179 for (i = 0; i < num_entries; i++) {
180 entry = &lookup[i];
181
182 if (!entry->dev_id || !entry->provider) {
183 pr_warn("%s(): reset lookup entry badly specified, skipping\n",
184 __func__);
185 continue;
186 }
187
188 list_add_tail(&entry->list, &reset_lookup_list);
189 }
190 mutex_unlock(&reset_lookup_mutex);
191}
192EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
193
194static inline struct reset_control_array *
195rstc_to_array(struct reset_control *rstc) {
196 return container_of(rstc, struct reset_control_array, base);
197}
198
199static int reset_control_array_reset(struct reset_control_array *resets)
200{
201 int ret, i;
202
203 for (i = 0; i < resets->num_rstcs; i++) {
204 ret = reset_control_reset(resets->rstc[i]);
205 if (ret)
206 return ret;
207 }
208
209 return 0;
210}
211
212static int reset_control_array_rearm(struct reset_control_array *resets)
213{
214 struct reset_control *rstc;
215 int i;
216
217 for (i = 0; i < resets->num_rstcs; i++) {
218 rstc = resets->rstc[i];
219
220 if (!rstc)
221 continue;
222
223 if (WARN_ON(IS_ERR(rstc)))
224 return -EINVAL;
225
226 if (rstc->shared) {
227 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
228 return -EINVAL;
229 } else {
230 if (!rstc->acquired)
231 return -EPERM;
232 }
233 }
234
235 for (i = 0; i < resets->num_rstcs; i++) {
236 rstc = resets->rstc[i];
237
238 if (rstc && rstc->shared)
239 WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);
240 }
241
242 return 0;
243}
244
245static int reset_control_array_assert(struct reset_control_array *resets)
246{
247 int ret, i;
248
249 for (i = 0; i < resets->num_rstcs; i++) {
250 ret = reset_control_assert(resets->rstc[i]);
251 if (ret)
252 goto err;
253 }
254
255 return 0;
256
257err:
258 while (i--)
259 reset_control_deassert(resets->rstc[i]);
260 return ret;
261}
262
263static int reset_control_array_deassert(struct reset_control_array *resets)
264{
265 int ret, i;
266
267 for (i = 0; i < resets->num_rstcs; i++) {
268 ret = reset_control_deassert(resets->rstc[i]);
269 if (ret)
270 goto err;
271 }
272
273 return 0;
274
275err:
276 while (i--)
277 reset_control_assert(resets->rstc[i]);
278 return ret;
279}
280
281static int reset_control_array_acquire(struct reset_control_array *resets)
282{
283 unsigned int i;
284 int err;
285
286 for (i = 0; i < resets->num_rstcs; i++) {
287 err = reset_control_acquire(resets->rstc[i]);
288 if (err < 0)
289 goto release;
290 }
291
292 return 0;
293
294release:
295 while (i--)
296 reset_control_release(resets->rstc[i]);
297
298 return err;
299}
300
301static void reset_control_array_release(struct reset_control_array *resets)
302{
303 unsigned int i;
304
305 for (i = 0; i < resets->num_rstcs; i++)
306 reset_control_release(resets->rstc[i]);
307}
308
309static inline bool reset_control_is_array(struct reset_control *rstc)
310{
311 return rstc->array;
312}
313
314/**
315 * reset_control_reset - reset the controlled device
316 * @rstc: reset controller
317 *
318 * On a shared reset line the actual reset pulse is only triggered once for the
319 * lifetime of the reset_control instance: for all but the first caller this is
320 * a no-op.
321 * Consumers must not use reset_control_(de)assert on shared reset lines when
322 * reset_control_reset has been used.
323 *
324 * If rstc is NULL it is an optional reset and the function will just
325 * return 0.
326 */
327int reset_control_reset(struct reset_control *rstc)
328{
329 int ret;
330
331 if (!rstc)
332 return 0;
333
334 if (WARN_ON(IS_ERR(rstc)))
335 return -EINVAL;
336
337 if (reset_control_is_array(rstc))
338 return reset_control_array_reset(rstc_to_array(rstc));
339
340 if (!rstc->rcdev->ops->reset)
341 return -ENOTSUPP;
342
343 if (rstc->shared) {
344 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
345 return -EINVAL;
346
347 if (atomic_inc_return(&rstc->triggered_count) != 1)
348 return 0;
349 } else {
350 if (!rstc->acquired)
351 return -EPERM;
352 }
353
354 ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
355 if (rstc->shared && ret)
356 atomic_dec(&rstc->triggered_count);
357
358 return ret;
359}
360EXPORT_SYMBOL_GPL(reset_control_reset);
361
362/**
363 * reset_control_bulk_reset - reset the controlled devices in order
364 * @num_rstcs: number of entries in rstcs array
365 * @rstcs: array of struct reset_control_bulk_data with reset controls set
366 *
367 * Issue a reset on all provided reset controls, in order.
368 *
369 * See also: reset_control_reset()
370 */
371int reset_control_bulk_reset(int num_rstcs,
372 struct reset_control_bulk_data *rstcs)
373{
374 int ret, i;
375
376 for (i = 0; i < num_rstcs; i++) {
377 ret = reset_control_reset(rstcs[i].rstc);
378 if (ret)
379 return ret;
380 }
381
382 return 0;
383}
384EXPORT_SYMBOL_GPL(reset_control_bulk_reset);
385
386/**
387 * reset_control_rearm - allow shared reset line to be re-triggered"
388 * @rstc: reset controller
389 *
390 * On a shared reset line the actual reset pulse is only triggered once for the
391 * lifetime of the reset_control instance, except if this call is used.
392 *
393 * Calls to this function must be balanced with calls to reset_control_reset,
394 * a warning is thrown in case triggered_count ever dips below 0.
395 *
396 * Consumers must not use reset_control_(de)assert on shared reset lines when
397 * reset_control_reset or reset_control_rearm have been used.
398 *
399 * If rstc is NULL the function will just return 0.
400 */
401int reset_control_rearm(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_rearm(rstc_to_array(rstc));
411
412 if (rstc->shared) {
413 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
414 return -EINVAL;
415
416 WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);
417 } else {
418 if (!rstc->acquired)
419 return -EPERM;
420 }
421
422 return 0;
423}
424EXPORT_SYMBOL_GPL(reset_control_rearm);
425
426/**
427 * reset_control_assert - asserts the reset line
428 * @rstc: reset controller
429 *
430 * Calling this on an exclusive reset controller guarantees that the reset
431 * will be asserted. When called on a shared reset controller the line may
432 * still be deasserted, as long as other users keep it so.
433 *
434 * For shared reset controls a driver cannot expect the hw's registers and
435 * internal state to be reset, but must be prepared for this to happen.
436 * Consumers must not use reset_control_reset on shared reset lines when
437 * reset_control_(de)assert has been used.
438 *
439 * If rstc is NULL it is an optional reset and the function will just
440 * return 0.
441 */
442int reset_control_assert(struct reset_control *rstc)
443{
444 if (!rstc)
445 return 0;
446
447 if (WARN_ON(IS_ERR(rstc)))
448 return -EINVAL;
449
450 if (reset_control_is_array(rstc))
451 return reset_control_array_assert(rstc_to_array(rstc));
452
453 if (rstc->shared) {
454 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
455 return -EINVAL;
456
457 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
458 return -EINVAL;
459
460 if (atomic_dec_return(&rstc->deassert_count) != 0)
461 return 0;
462
463 /*
464 * Shared reset controls allow the reset line to be in any state
465 * after this call, so doing nothing is a valid option.
466 */
467 if (!rstc->rcdev->ops->assert)
468 return 0;
469 } else {
470 /*
471 * If the reset controller does not implement .assert(), there
472 * is no way to guarantee that the reset line is asserted after
473 * this call.
474 */
475 if (!rstc->rcdev->ops->assert)
476 return -ENOTSUPP;
477
478 if (!rstc->acquired) {
479 WARN(1, "reset %s (ID: %u) is not acquired\n",
480 rcdev_name(rstc->rcdev), rstc->id);
481 return -EPERM;
482 }
483 }
484
485 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
486}
487EXPORT_SYMBOL_GPL(reset_control_assert);
488
489/**
490 * reset_control_bulk_assert - asserts the reset lines in order
491 * @num_rstcs: number of entries in rstcs array
492 * @rstcs: array of struct reset_control_bulk_data with reset controls set
493 *
494 * Assert the reset lines for all provided reset controls, in order.
495 * If an assertion fails, already asserted resets are deasserted again.
496 *
497 * See also: reset_control_assert()
498 */
499int reset_control_bulk_assert(int num_rstcs,
500 struct reset_control_bulk_data *rstcs)
501{
502 int ret, i;
503
504 for (i = 0; i < num_rstcs; i++) {
505 ret = reset_control_assert(rstcs[i].rstc);
506 if (ret)
507 goto err;
508 }
509
510 return 0;
511
512err:
513 while (i--)
514 reset_control_deassert(rstcs[i].rstc);
515 return ret;
516}
517EXPORT_SYMBOL_GPL(reset_control_bulk_assert);
518
519/**
520 * reset_control_deassert - deasserts the reset line
521 * @rstc: reset controller
522 *
523 * After calling this function, the reset is guaranteed to be deasserted.
524 * Consumers must not use reset_control_reset on shared reset lines when
525 * reset_control_(de)assert has been used.
526 *
527 * If rstc is NULL it is an optional reset and the function will just
528 * return 0.
529 */
530int reset_control_deassert(struct reset_control *rstc)
531{
532 if (!rstc)
533 return 0;
534
535 if (WARN_ON(IS_ERR(rstc)))
536 return -EINVAL;
537
538 if (reset_control_is_array(rstc))
539 return reset_control_array_deassert(rstc_to_array(rstc));
540
541 if (rstc->shared) {
542 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
543 return -EINVAL;
544
545 if (atomic_inc_return(&rstc->deassert_count) != 1)
546 return 0;
547 } else {
548 if (!rstc->acquired) {
549 WARN(1, "reset %s (ID: %u) is not acquired\n",
550 rcdev_name(rstc->rcdev), rstc->id);
551 return -EPERM;
552 }
553 }
554
555 /*
556 * If the reset controller does not implement .deassert(), we assume
557 * that it handles self-deasserting reset lines via .reset(). In that
558 * case, the reset lines are deasserted by default. If that is not the
559 * case, the reset controller driver should implement .deassert() and
560 * return -ENOTSUPP.
561 */
562 if (!rstc->rcdev->ops->deassert)
563 return 0;
564
565 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
566}
567EXPORT_SYMBOL_GPL(reset_control_deassert);
568
569/**
570 * reset_control_bulk_deassert - deasserts the reset lines in reverse order
571 * @num_rstcs: number of entries in rstcs array
572 * @rstcs: array of struct reset_control_bulk_data with reset controls set
573 *
574 * Deassert the reset lines for all provided reset controls, in reverse order.
575 * If a deassertion fails, already deasserted resets are asserted again.
576 *
577 * See also: reset_control_deassert()
578 */
579int reset_control_bulk_deassert(int num_rstcs,
580 struct reset_control_bulk_data *rstcs)
581{
582 int ret, i;
583
584 for (i = num_rstcs - 1; i >= 0; i--) {
585 ret = reset_control_deassert(rstcs[i].rstc);
586 if (ret)
587 goto err;
588 }
589
590 return 0;
591
592err:
593 while (i < num_rstcs)
594 reset_control_assert(rstcs[i++].rstc);
595 return ret;
596}
597EXPORT_SYMBOL_GPL(reset_control_bulk_deassert);
598
599/**
600 * reset_control_status - returns a negative errno if not supported, a
601 * positive value if the reset line is asserted, or zero if the reset
602 * line is not asserted or if the desc is NULL (optional reset).
603 * @rstc: reset controller
604 */
605int reset_control_status(struct reset_control *rstc)
606{
607 if (!rstc)
608 return 0;
609
610 if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
611 return -EINVAL;
612
613 if (rstc->rcdev->ops->status)
614 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
615
616 return -ENOTSUPP;
617}
618EXPORT_SYMBOL_GPL(reset_control_status);
619
620/**
621 * reset_control_acquire() - acquires a reset control for exclusive use
622 * @rstc: reset control
623 *
624 * This is used to explicitly acquire a reset control for exclusive use. Note
625 * that exclusive resets are requested as acquired by default. In order for a
626 * second consumer to be able to control the reset, the first consumer has to
627 * release it first. Typically the easiest way to achieve this is to call the
628 * reset_control_get_exclusive_released() to obtain an instance of the reset
629 * control. Such reset controls are not acquired by default.
630 *
631 * Consumers implementing shared access to an exclusive reset need to follow
632 * a specific protocol in order to work together. Before consumers can change
633 * a reset they must acquire exclusive access using reset_control_acquire().
634 * After they are done operating the reset, they must release exclusive access
635 * with a call to reset_control_release(). Consumers are not granted exclusive
636 * access to the reset as long as another consumer hasn't released a reset.
637 *
638 * See also: reset_control_release()
639 */
640int reset_control_acquire(struct reset_control *rstc)
641{
642 struct reset_control *rc;
643
644 if (!rstc)
645 return 0;
646
647 if (WARN_ON(IS_ERR(rstc)))
648 return -EINVAL;
649
650 if (reset_control_is_array(rstc))
651 return reset_control_array_acquire(rstc_to_array(rstc));
652
653 mutex_lock(&reset_list_mutex);
654
655 if (rstc->acquired) {
656 mutex_unlock(&reset_list_mutex);
657 return 0;
658 }
659
660 list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
661 if (rstc != rc && rstc->id == rc->id) {
662 if (rc->acquired) {
663 mutex_unlock(&reset_list_mutex);
664 return -EBUSY;
665 }
666 }
667 }
668
669 rstc->acquired = true;
670
671 mutex_unlock(&reset_list_mutex);
672 return 0;
673}
674EXPORT_SYMBOL_GPL(reset_control_acquire);
675
676/**
677 * reset_control_bulk_acquire - acquires reset controls for exclusive use
678 * @num_rstcs: number of entries in rstcs array
679 * @rstcs: array of struct reset_control_bulk_data with reset controls set
680 *
681 * This is used to explicitly acquire reset controls requested with
682 * reset_control_bulk_get_exclusive_release() for temporary exclusive use.
683 *
684 * See also: reset_control_acquire(), reset_control_bulk_release()
685 */
686int reset_control_bulk_acquire(int num_rstcs,
687 struct reset_control_bulk_data *rstcs)
688{
689 int ret, i;
690
691 for (i = 0; i < num_rstcs; i++) {
692 ret = reset_control_acquire(rstcs[i].rstc);
693 if (ret)
694 goto err;
695 }
696
697 return 0;
698
699err:
700 while (i--)
701 reset_control_release(rstcs[i].rstc);
702 return ret;
703}
704EXPORT_SYMBOL_GPL(reset_control_bulk_acquire);
705
706/**
707 * reset_control_release() - releases exclusive access to a reset control
708 * @rstc: reset control
709 *
710 * Releases exclusive access right to a reset control previously obtained by a
711 * call to reset_control_acquire(). Until a consumer calls this function, no
712 * other consumers will be granted exclusive access.
713 *
714 * See also: reset_control_acquire()
715 */
716void reset_control_release(struct reset_control *rstc)
717{
718 if (!rstc || WARN_ON(IS_ERR(rstc)))
719 return;
720
721 if (reset_control_is_array(rstc))
722 reset_control_array_release(rstc_to_array(rstc));
723 else
724 rstc->acquired = false;
725}
726EXPORT_SYMBOL_GPL(reset_control_release);
727
728/**
729 * reset_control_bulk_release() - releases exclusive access to reset controls
730 * @num_rstcs: number of entries in rstcs array
731 * @rstcs: array of struct reset_control_bulk_data with reset controls set
732 *
733 * Releases exclusive access right to reset controls previously obtained by a
734 * call to reset_control_bulk_acquire().
735 *
736 * See also: reset_control_release(), reset_control_bulk_acquire()
737 */
738void reset_control_bulk_release(int num_rstcs,
739 struct reset_control_bulk_data *rstcs)
740{
741 int i;
742
743 for (i = 0; i < num_rstcs; i++)
744 reset_control_release(rstcs[i].rstc);
745}
746EXPORT_SYMBOL_GPL(reset_control_bulk_release);
747
748static struct reset_control *
749__reset_control_get_internal(struct reset_controller_dev *rcdev,
750 unsigned int index, bool shared, bool acquired)
751{
752 struct reset_control *rstc;
753
754 lockdep_assert_held(&reset_list_mutex);
755
756 list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
757 if (rstc->id == index) {
758 /*
759 * Allow creating a secondary exclusive reset_control
760 * that is initially not acquired for an already
761 * controlled reset line.
762 */
763 if (!rstc->shared && !shared && !acquired)
764 break;
765
766 if (WARN_ON(!rstc->shared || !shared))
767 return ERR_PTR(-EBUSY);
768
769 kref_get(&rstc->refcnt);
770 return rstc;
771 }
772 }
773
774 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
775 if (!rstc)
776 return ERR_PTR(-ENOMEM);
777
778 if (!try_module_get(rcdev->owner)) {
779 kfree(rstc);
780 return ERR_PTR(-ENODEV);
781 }
782
783 rstc->rcdev = rcdev;
784 list_add(&rstc->list, &rcdev->reset_control_head);
785 rstc->id = index;
786 kref_init(&rstc->refcnt);
787 rstc->acquired = acquired;
788 rstc->shared = shared;
789
790 return rstc;
791}
792
793static void __reset_control_release(struct kref *kref)
794{
795 struct reset_control *rstc = container_of(kref, struct reset_control,
796 refcnt);
797
798 lockdep_assert_held(&reset_list_mutex);
799
800 module_put(rstc->rcdev->owner);
801
802 list_del(&rstc->list);
803 kfree(rstc);
804}
805
806static void __reset_control_put_internal(struct reset_control *rstc)
807{
808 lockdep_assert_held(&reset_list_mutex);
809
810 kref_put(&rstc->refcnt, __reset_control_release);
811}
812
813struct reset_control *
814__of_reset_control_get(struct device_node *node, const char *id, int index,
815 bool shared, bool optional, bool acquired)
816{
817 struct reset_control *rstc;
818 struct reset_controller_dev *r, *rcdev;
819 struct of_phandle_args args;
820 int rstc_id;
821 int ret;
822
823 if (!node)
824 return ERR_PTR(-EINVAL);
825
826 if (id) {
827 index = of_property_match_string(node,
828 "reset-names", id);
829 if (index == -EILSEQ)
830 return ERR_PTR(index);
831 if (index < 0)
832 return optional ? NULL : ERR_PTR(-ENOENT);
833 }
834
835 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
836 index, &args);
837 if (ret == -EINVAL)
838 return ERR_PTR(ret);
839 if (ret)
840 return optional ? NULL : ERR_PTR(ret);
841
842 mutex_lock(&reset_list_mutex);
843 rcdev = NULL;
844 list_for_each_entry(r, &reset_controller_list, list) {
845 if (args.np == r->of_node) {
846 rcdev = r;
847 break;
848 }
849 }
850
851 if (!rcdev) {
852 rstc = ERR_PTR(-EPROBE_DEFER);
853 goto out;
854 }
855
856 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
857 rstc = ERR_PTR(-EINVAL);
858 goto out;
859 }
860
861 rstc_id = rcdev->of_xlate(rcdev, &args);
862 if (rstc_id < 0) {
863 rstc = ERR_PTR(rstc_id);
864 goto out;
865 }
866
867 /* reset_list_mutex also protects the rcdev's reset_control list */
868 rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
869
870out:
871 mutex_unlock(&reset_list_mutex);
872 of_node_put(args.np);
873
874 return rstc;
875}
876EXPORT_SYMBOL_GPL(__of_reset_control_get);
877
878static struct reset_controller_dev *
879__reset_controller_by_name(const char *name)
880{
881 struct reset_controller_dev *rcdev;
882
883 lockdep_assert_held(&reset_list_mutex);
884
885 list_for_each_entry(rcdev, &reset_controller_list, list) {
886 if (!rcdev->dev)
887 continue;
888
889 if (!strcmp(name, dev_name(rcdev->dev)))
890 return rcdev;
891 }
892
893 return NULL;
894}
895
896static struct reset_control *
897__reset_control_get_from_lookup(struct device *dev, const char *con_id,
898 bool shared, bool optional, bool acquired)
899{
900 const struct reset_control_lookup *lookup;
901 struct reset_controller_dev *rcdev;
902 const char *dev_id = dev_name(dev);
903 struct reset_control *rstc = NULL;
904
905 mutex_lock(&reset_lookup_mutex);
906
907 list_for_each_entry(lookup, &reset_lookup_list, list) {
908 if (strcmp(lookup->dev_id, dev_id))
909 continue;
910
911 if ((!con_id && !lookup->con_id) ||
912 ((con_id && lookup->con_id) &&
913 !strcmp(con_id, lookup->con_id))) {
914 mutex_lock(&reset_list_mutex);
915 rcdev = __reset_controller_by_name(lookup->provider);
916 if (!rcdev) {
917 mutex_unlock(&reset_list_mutex);
918 mutex_unlock(&reset_lookup_mutex);
919 /* Reset provider may not be ready yet. */
920 return ERR_PTR(-EPROBE_DEFER);
921 }
922
923 rstc = __reset_control_get_internal(rcdev,
924 lookup->index,
925 shared, acquired);
926 mutex_unlock(&reset_list_mutex);
927 break;
928 }
929 }
930
931 mutex_unlock(&reset_lookup_mutex);
932
933 if (!rstc)
934 return optional ? NULL : ERR_PTR(-ENOENT);
935
936 return rstc;
937}
938
939struct reset_control *__reset_control_get(struct device *dev, const char *id,
940 int index, bool shared, bool optional,
941 bool acquired)
942{
943 if (WARN_ON(shared && acquired))
944 return ERR_PTR(-EINVAL);
945
946 if (dev->of_node)
947 return __of_reset_control_get(dev->of_node, id, index, shared,
948 optional, acquired);
949
950 return __reset_control_get_from_lookup(dev, id, shared, optional,
951 acquired);
952}
953EXPORT_SYMBOL_GPL(__reset_control_get);
954
955int __reset_control_bulk_get(struct device *dev, int num_rstcs,
956 struct reset_control_bulk_data *rstcs,
957 bool shared, bool optional, bool acquired)
958{
959 int ret, i;
960
961 for (i = 0; i < num_rstcs; i++) {
962 rstcs[i].rstc = __reset_control_get(dev, rstcs[i].id, 0,
963 shared, optional, acquired);
964 if (IS_ERR(rstcs[i].rstc)) {
965 ret = PTR_ERR(rstcs[i].rstc);
966 goto err;
967 }
968 }
969
970 return 0;
971
972err:
973 mutex_lock(&reset_list_mutex);
974 while (i--)
975 __reset_control_put_internal(rstcs[i].rstc);
976 mutex_unlock(&reset_list_mutex);
977 return ret;
978}
979EXPORT_SYMBOL_GPL(__reset_control_bulk_get);
980
981static void reset_control_array_put(struct reset_control_array *resets)
982{
983 int i;
984
985 mutex_lock(&reset_list_mutex);
986 for (i = 0; i < resets->num_rstcs; i++)
987 __reset_control_put_internal(resets->rstc[i]);
988 mutex_unlock(&reset_list_mutex);
989 kfree(resets);
990}
991
992/**
993 * reset_control_put - free the reset controller
994 * @rstc: reset controller
995 */
996void reset_control_put(struct reset_control *rstc)
997{
998 if (IS_ERR_OR_NULL(rstc))
999 return;
1000
1001 if (reset_control_is_array(rstc)) {
1002 reset_control_array_put(rstc_to_array(rstc));
1003 return;
1004 }
1005
1006 mutex_lock(&reset_list_mutex);
1007 __reset_control_put_internal(rstc);
1008 mutex_unlock(&reset_list_mutex);
1009}
1010EXPORT_SYMBOL_GPL(reset_control_put);
1011
1012/**
1013 * reset_control_bulk_put - free the reset controllers
1014 * @num_rstcs: number of entries in rstcs array
1015 * @rstcs: array of struct reset_control_bulk_data with reset controls set
1016 */
1017void reset_control_bulk_put(int num_rstcs, struct reset_control_bulk_data *rstcs)
1018{
1019 mutex_lock(&reset_list_mutex);
1020 while (num_rstcs--) {
1021 if (IS_ERR_OR_NULL(rstcs[num_rstcs].rstc))
1022 continue;
1023 __reset_control_put_internal(rstcs[num_rstcs].rstc);
1024 }
1025 mutex_unlock(&reset_list_mutex);
1026}
1027EXPORT_SYMBOL_GPL(reset_control_bulk_put);
1028
1029static void devm_reset_control_release(struct device *dev, void *res)
1030{
1031 reset_control_put(*(struct reset_control **)res);
1032}
1033
1034struct reset_control *
1035__devm_reset_control_get(struct device *dev, const char *id, int index,
1036 bool shared, bool optional, bool acquired)
1037{
1038 struct reset_control **ptr, *rstc;
1039
1040 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
1041 GFP_KERNEL);
1042 if (!ptr)
1043 return ERR_PTR(-ENOMEM);
1044
1045 rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
1046 if (IS_ERR_OR_NULL(rstc)) {
1047 devres_free(ptr);
1048 return rstc;
1049 }
1050
1051 *ptr = rstc;
1052 devres_add(dev, ptr);
1053
1054 return rstc;
1055}
1056EXPORT_SYMBOL_GPL(__devm_reset_control_get);
1057
1058struct reset_control_bulk_devres {
1059 int num_rstcs;
1060 struct reset_control_bulk_data *rstcs;
1061};
1062
1063static void devm_reset_control_bulk_release(struct device *dev, void *res)
1064{
1065 struct reset_control_bulk_devres *devres = res;
1066
1067 reset_control_bulk_put(devres->num_rstcs, devres->rstcs);
1068}
1069
1070int __devm_reset_control_bulk_get(struct device *dev, int num_rstcs,
1071 struct reset_control_bulk_data *rstcs,
1072 bool shared, bool optional, bool acquired)
1073{
1074 struct reset_control_bulk_devres *ptr;
1075 int ret;
1076
1077 ptr = devres_alloc(devm_reset_control_bulk_release, sizeof(*ptr),
1078 GFP_KERNEL);
1079 if (!ptr)
1080 return -ENOMEM;
1081
1082 ret = __reset_control_bulk_get(dev, num_rstcs, rstcs, shared, optional, acquired);
1083 if (ret < 0) {
1084 devres_free(ptr);
1085 return ret;
1086 }
1087
1088 ptr->num_rstcs = num_rstcs;
1089 ptr->rstcs = rstcs;
1090 devres_add(dev, ptr);
1091
1092 return 0;
1093}
1094EXPORT_SYMBOL_GPL(__devm_reset_control_bulk_get);
1095
1096/**
1097 * __device_reset - find reset controller associated with the device
1098 * and perform reset
1099 * @dev: device to be reset by the controller
1100 * @optional: whether it is optional to reset the device
1101 *
1102 * Convenience wrapper for __reset_control_get() and reset_control_reset().
1103 * This is useful for the common case of devices with single, dedicated reset
1104 * lines. _RST firmware method will be called for devices with ACPI.
1105 */
1106int __device_reset(struct device *dev, bool optional)
1107{
1108 struct reset_control *rstc;
1109 int ret;
1110
1111#ifdef CONFIG_ACPI
1112 acpi_handle handle = ACPI_HANDLE(dev);
1113
1114 if (handle) {
1115 if (!acpi_has_method(handle, "_RST"))
1116 return optional ? 0 : -ENOENT;
1117 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL,
1118 NULL)))
1119 return -EIO;
1120 }
1121#endif
1122
1123 rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
1124 if (IS_ERR(rstc))
1125 return PTR_ERR(rstc);
1126
1127 ret = reset_control_reset(rstc);
1128
1129 reset_control_put(rstc);
1130
1131 return ret;
1132}
1133EXPORT_SYMBOL_GPL(__device_reset);
1134
1135/*
1136 * APIs to manage an array of reset controls.
1137 */
1138
1139/**
1140 * of_reset_control_get_count - Count number of resets available with a device
1141 *
1142 * @node: device node that contains 'resets'.
1143 *
1144 * Returns positive reset count on success, or error number on failure and
1145 * on count being zero.
1146 */
1147static int of_reset_control_get_count(struct device_node *node)
1148{
1149 int count;
1150
1151 if (!node)
1152 return -EINVAL;
1153
1154 count = of_count_phandle_with_args(node, "resets", "#reset-cells");
1155 if (count == 0)
1156 count = -ENOENT;
1157
1158 return count;
1159}
1160
1161/**
1162 * of_reset_control_array_get - Get a list of reset controls using
1163 * device node.
1164 *
1165 * @np: device node for the device that requests the reset controls array
1166 * @shared: whether reset controls are shared or not
1167 * @optional: whether it is optional to get the reset controls
1168 * @acquired: only one reset control may be acquired for a given controller
1169 * and ID
1170 *
1171 * Returns pointer to allocated reset_control on success or error on failure
1172 */
1173struct reset_control *
1174of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
1175 bool acquired)
1176{
1177 struct reset_control_array *resets;
1178 struct reset_control *rstc;
1179 int num, i;
1180
1181 num = of_reset_control_get_count(np);
1182 if (num < 0)
1183 return optional ? NULL : ERR_PTR(num);
1184
1185 resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
1186 if (!resets)
1187 return ERR_PTR(-ENOMEM);
1188
1189 for (i = 0; i < num; i++) {
1190 rstc = __of_reset_control_get(np, NULL, i, shared, optional,
1191 acquired);
1192 if (IS_ERR(rstc))
1193 goto err_rst;
1194 resets->rstc[i] = rstc;
1195 }
1196 resets->num_rstcs = num;
1197 resets->base.array = true;
1198
1199 return &resets->base;
1200
1201err_rst:
1202 mutex_lock(&reset_list_mutex);
1203 while (--i >= 0)
1204 __reset_control_put_internal(resets->rstc[i]);
1205 mutex_unlock(&reset_list_mutex);
1206
1207 kfree(resets);
1208
1209 return rstc;
1210}
1211EXPORT_SYMBOL_GPL(of_reset_control_array_get);
1212
1213/**
1214 * devm_reset_control_array_get - Resource managed reset control array get
1215 *
1216 * @dev: device that requests the list of reset controls
1217 * @shared: whether reset controls are shared or not
1218 * @optional: whether it is optional to get the reset controls
1219 *
1220 * The reset control array APIs are intended for a list of resets
1221 * that just have to be asserted or deasserted, without any
1222 * requirements on the order.
1223 *
1224 * Returns pointer to allocated reset_control on success or error on failure
1225 */
1226struct reset_control *
1227devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
1228{
1229 struct reset_control **ptr, *rstc;
1230
1231 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
1232 GFP_KERNEL);
1233 if (!ptr)
1234 return ERR_PTR(-ENOMEM);
1235
1236 rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
1237 if (IS_ERR_OR_NULL(rstc)) {
1238 devres_free(ptr);
1239 return rstc;
1240 }
1241
1242 *ptr = rstc;
1243 devres_add(dev, ptr);
1244
1245 return rstc;
1246}
1247EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
1248
1249static int reset_control_get_count_from_lookup(struct device *dev)
1250{
1251 const struct reset_control_lookup *lookup;
1252 const char *dev_id;
1253 int count = 0;
1254
1255 if (!dev)
1256 return -EINVAL;
1257
1258 dev_id = dev_name(dev);
1259 mutex_lock(&reset_lookup_mutex);
1260
1261 list_for_each_entry(lookup, &reset_lookup_list, list) {
1262 if (!strcmp(lookup->dev_id, dev_id))
1263 count++;
1264 }
1265
1266 mutex_unlock(&reset_lookup_mutex);
1267
1268 if (count == 0)
1269 count = -ENOENT;
1270
1271 return count;
1272}
1273
1274/**
1275 * reset_control_get_count - Count number of resets available with a device
1276 *
1277 * @dev: device for which to return the number of resets
1278 *
1279 * Returns positive reset count on success, or error number on failure and
1280 * on count being zero.
1281 */
1282int reset_control_get_count(struct device *dev)
1283{
1284 if (dev->of_node)
1285 return of_reset_control_get_count(dev->of_node);
1286
1287 return reset_control_get_count_from_lookup(dev);
1288}
1289EXPORT_SYMBOL_GPL(reset_control_get_count);