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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/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 * @array: Is this an array of reset controls (1)?
36 * @deassert_count: Number of times this reset line has been deasserted
37 * @triggered_count: Number of times this reset line has been reset. Currently
38 * only used for shared resets, which means that the value
39 * will be either 0 or 1.
40 */
41struct reset_control {
42 struct reset_controller_dev *rcdev;
43 struct list_head list;
44 unsigned int id;
45 struct kref refcnt;
46 bool acquired;
47 bool shared;
48 bool array;
49 atomic_t deassert_count;
50 atomic_t triggered_count;
51};
52
53/**
54 * struct reset_control_array - an array of reset controls
55 * @base: reset control for compatibility with reset control API functions
56 * @num_rstcs: number of reset controls
57 * @rstc: array of reset controls
58 */
59struct reset_control_array {
60 struct reset_control base;
61 unsigned int num_rstcs;
62 struct reset_control *rstc[];
63};
64
65static const char *rcdev_name(struct reset_controller_dev *rcdev)
66{
67 if (rcdev->dev)
68 return dev_name(rcdev->dev);
69
70 if (rcdev->of_node)
71 return rcdev->of_node->full_name;
72
73 return NULL;
74}
75
76/**
77 * of_reset_simple_xlate - translate reset_spec to the reset line number
78 * @rcdev: a pointer to the reset controller device
79 * @reset_spec: reset line specifier as found in the device tree
80 *
81 * This static translation function is used by default if of_xlate in
82 * :c:type:`reset_controller_dev` is not set. It is useful for all reset
83 * controllers with 1:1 mapping, where reset lines can be indexed by number
84 * without gaps.
85 */
86static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
87 const struct of_phandle_args *reset_spec)
88{
89 if (reset_spec->args[0] >= rcdev->nr_resets)
90 return -EINVAL;
91
92 return reset_spec->args[0];
93}
94
95/**
96 * reset_controller_register - register a reset controller device
97 * @rcdev: a pointer to the initialized reset controller device
98 */
99int reset_controller_register(struct reset_controller_dev *rcdev)
100{
101 if (!rcdev->of_xlate) {
102 rcdev->of_reset_n_cells = 1;
103 rcdev->of_xlate = of_reset_simple_xlate;
104 }
105
106 INIT_LIST_HEAD(&rcdev->reset_control_head);
107
108 mutex_lock(&reset_list_mutex);
109 list_add(&rcdev->list, &reset_controller_list);
110 mutex_unlock(&reset_list_mutex);
111
112 return 0;
113}
114EXPORT_SYMBOL_GPL(reset_controller_register);
115
116/**
117 * reset_controller_unregister - unregister a reset controller device
118 * @rcdev: a pointer to the reset controller device
119 */
120void reset_controller_unregister(struct reset_controller_dev *rcdev)
121{
122 mutex_lock(&reset_list_mutex);
123 list_del(&rcdev->list);
124 mutex_unlock(&reset_list_mutex);
125}
126EXPORT_SYMBOL_GPL(reset_controller_unregister);
127
128static void devm_reset_controller_release(struct device *dev, void *res)
129{
130 reset_controller_unregister(*(struct reset_controller_dev **)res);
131}
132
133/**
134 * devm_reset_controller_register - resource managed reset_controller_register()
135 * @dev: device that is registering this reset controller
136 * @rcdev: a pointer to the initialized reset controller device
137 *
138 * Managed reset_controller_register(). For reset controllers registered by
139 * this function, reset_controller_unregister() is automatically called on
140 * driver detach. See reset_controller_register() for more information.
141 */
142int devm_reset_controller_register(struct device *dev,
143 struct reset_controller_dev *rcdev)
144{
145 struct reset_controller_dev **rcdevp;
146 int ret;
147
148 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
149 GFP_KERNEL);
150 if (!rcdevp)
151 return -ENOMEM;
152
153 ret = reset_controller_register(rcdev);
154 if (ret) {
155 devres_free(rcdevp);
156 return ret;
157 }
158
159 *rcdevp = rcdev;
160 devres_add(dev, rcdevp);
161
162 return ret;
163}
164EXPORT_SYMBOL_GPL(devm_reset_controller_register);
165
166/**
167 * reset_controller_add_lookup - register a set of lookup entries
168 * @lookup: array of reset lookup entries
169 * @num_entries: number of entries in the lookup array
170 */
171void reset_controller_add_lookup(struct reset_control_lookup *lookup,
172 unsigned int num_entries)
173{
174 struct reset_control_lookup *entry;
175 unsigned int i;
176
177 mutex_lock(&reset_lookup_mutex);
178 for (i = 0; i < num_entries; i++) {
179 entry = &lookup[i];
180
181 if (!entry->dev_id || !entry->provider) {
182 pr_warn("%s(): reset lookup entry badly specified, skipping\n",
183 __func__);
184 continue;
185 }
186
187 list_add_tail(&entry->list, &reset_lookup_list);
188 }
189 mutex_unlock(&reset_lookup_mutex);
190}
191EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
192
193static inline struct reset_control_array *
194rstc_to_array(struct reset_control *rstc) {
195 return container_of(rstc, struct reset_control_array, base);
196}
197
198static int reset_control_array_reset(struct reset_control_array *resets)
199{
200 int ret, i;
201
202 for (i = 0; i < resets->num_rstcs; i++) {
203 ret = reset_control_reset(resets->rstc[i]);
204 if (ret)
205 return ret;
206 }
207
208 return 0;
209}
210
211static int reset_control_array_rearm(struct reset_control_array *resets)
212{
213 struct reset_control *rstc;
214 int i;
215
216 for (i = 0; i < resets->num_rstcs; i++) {
217 rstc = resets->rstc[i];
218
219 if (!rstc)
220 continue;
221
222 if (WARN_ON(IS_ERR(rstc)))
223 return -EINVAL;
224
225 if (rstc->shared) {
226 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
227 return -EINVAL;
228 } else {
229 if (!rstc->acquired)
230 return -EPERM;
231 }
232 }
233
234 for (i = 0; i < resets->num_rstcs; i++) {
235 rstc = resets->rstc[i];
236
237 if (rstc && rstc->shared)
238 WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);
239 }
240
241 return 0;
242}
243
244static int reset_control_array_assert(struct reset_control_array *resets)
245{
246 int ret, i;
247
248 for (i = 0; i < resets->num_rstcs; i++) {
249 ret = reset_control_assert(resets->rstc[i]);
250 if (ret)
251 goto err;
252 }
253
254 return 0;
255
256err:
257 while (i--)
258 reset_control_deassert(resets->rstc[i]);
259 return ret;
260}
261
262static int reset_control_array_deassert(struct reset_control_array *resets)
263{
264 int ret, i;
265
266 for (i = 0; i < resets->num_rstcs; i++) {
267 ret = reset_control_deassert(resets->rstc[i]);
268 if (ret)
269 goto err;
270 }
271
272 return 0;
273
274err:
275 while (i--)
276 reset_control_assert(resets->rstc[i]);
277 return ret;
278}
279
280static int reset_control_array_acquire(struct reset_control_array *resets)
281{
282 unsigned int i;
283 int err;
284
285 for (i = 0; i < resets->num_rstcs; i++) {
286 err = reset_control_acquire(resets->rstc[i]);
287 if (err < 0)
288 goto release;
289 }
290
291 return 0;
292
293release:
294 while (i--)
295 reset_control_release(resets->rstc[i]);
296
297 return err;
298}
299
300static void reset_control_array_release(struct reset_control_array *resets)
301{
302 unsigned int i;
303
304 for (i = 0; i < resets->num_rstcs; i++)
305 reset_control_release(resets->rstc[i]);
306}
307
308static inline bool reset_control_is_array(struct reset_control *rstc)
309{
310 return rstc->array;
311}
312
313/**
314 * reset_control_reset - reset the controlled device
315 * @rstc: reset controller
316 *
317 * On a shared reset line the actual reset pulse is only triggered once for the
318 * lifetime of the reset_control instance: for all but the first caller this is
319 * a no-op.
320 * Consumers must not use reset_control_(de)assert on shared reset lines when
321 * reset_control_reset has been used.
322 *
323 * If rstc is NULL it is an optional reset and the function will just
324 * return 0.
325 */
326int reset_control_reset(struct reset_control *rstc)
327{
328 int ret;
329
330 if (!rstc)
331 return 0;
332
333 if (WARN_ON(IS_ERR(rstc)))
334 return -EINVAL;
335
336 if (reset_control_is_array(rstc))
337 return reset_control_array_reset(rstc_to_array(rstc));
338
339 if (!rstc->rcdev->ops->reset)
340 return -ENOTSUPP;
341
342 if (rstc->shared) {
343 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
344 return -EINVAL;
345
346 if (atomic_inc_return(&rstc->triggered_count) != 1)
347 return 0;
348 } else {
349 if (!rstc->acquired)
350 return -EPERM;
351 }
352
353 ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
354 if (rstc->shared && ret)
355 atomic_dec(&rstc->triggered_count);
356
357 return ret;
358}
359EXPORT_SYMBOL_GPL(reset_control_reset);
360
361/**
362 * reset_control_bulk_reset - reset the controlled devices in order
363 * @num_rstcs: number of entries in rstcs array
364 * @rstcs: array of struct reset_control_bulk_data with reset controls set
365 *
366 * Issue a reset on all provided reset controls, in order.
367 *
368 * See also: reset_control_reset()
369 */
370int reset_control_bulk_reset(int num_rstcs,
371 struct reset_control_bulk_data *rstcs)
372{
373 int ret, i;
374
375 for (i = 0; i < num_rstcs; i++) {
376 ret = reset_control_reset(rstcs[i].rstc);
377 if (ret)
378 return ret;
379 }
380
381 return 0;
382}
383EXPORT_SYMBOL_GPL(reset_control_bulk_reset);
384
385/**
386 * reset_control_rearm - allow shared reset line to be re-triggered"
387 * @rstc: reset controller
388 *
389 * On a shared reset line the actual reset pulse is only triggered once for the
390 * lifetime of the reset_control instance, except if this call is used.
391 *
392 * Calls to this function must be balanced with calls to reset_control_reset,
393 * a warning is thrown in case triggered_count ever dips below 0.
394 *
395 * Consumers must not use reset_control_(de)assert on shared reset lines when
396 * reset_control_reset or reset_control_rearm have been used.
397 *
398 * If rstc is NULL the function will just return 0.
399 */
400int reset_control_rearm(struct reset_control *rstc)
401{
402 if (!rstc)
403 return 0;
404
405 if (WARN_ON(IS_ERR(rstc)))
406 return -EINVAL;
407
408 if (reset_control_is_array(rstc))
409 return reset_control_array_rearm(rstc_to_array(rstc));
410
411 if (rstc->shared) {
412 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
413 return -EINVAL;
414
415 WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);
416 } else {
417 if (!rstc->acquired)
418 return -EPERM;
419 }
420
421 return 0;
422}
423EXPORT_SYMBOL_GPL(reset_control_rearm);
424
425/**
426 * reset_control_assert - asserts the reset line
427 * @rstc: reset controller
428 *
429 * Calling this on an exclusive reset controller guarantees that the reset
430 * will be asserted. When called on a shared reset controller the line may
431 * still be deasserted, as long as other users keep it so.
432 *
433 * For shared reset controls a driver cannot expect the hw's registers and
434 * internal state to be reset, but must be prepared for this to happen.
435 * Consumers must not use reset_control_reset on shared reset lines when
436 * reset_control_(de)assert has been used.
437 *
438 * If rstc is NULL it is an optional reset and the function will just
439 * return 0.
440 */
441int reset_control_assert(struct reset_control *rstc)
442{
443 if (!rstc)
444 return 0;
445
446 if (WARN_ON(IS_ERR(rstc)))
447 return -EINVAL;
448
449 if (reset_control_is_array(rstc))
450 return reset_control_array_assert(rstc_to_array(rstc));
451
452 if (rstc->shared) {
453 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
454 return -EINVAL;
455
456 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
457 return -EINVAL;
458
459 if (atomic_dec_return(&rstc->deassert_count) != 0)
460 return 0;
461
462 /*
463 * Shared reset controls allow the reset line to be in any state
464 * after this call, so doing nothing is a valid option.
465 */
466 if (!rstc->rcdev->ops->assert)
467 return 0;
468 } else {
469 /*
470 * If the reset controller does not implement .assert(), there
471 * is no way to guarantee that the reset line is asserted after
472 * this call.
473 */
474 if (!rstc->rcdev->ops->assert)
475 return -ENOTSUPP;
476
477 if (!rstc->acquired) {
478 WARN(1, "reset %s (ID: %u) is not acquired\n",
479 rcdev_name(rstc->rcdev), rstc->id);
480 return -EPERM;
481 }
482 }
483
484 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
485}
486EXPORT_SYMBOL_GPL(reset_control_assert);
487
488/**
489 * reset_control_bulk_assert - asserts the reset lines in order
490 * @num_rstcs: number of entries in rstcs array
491 * @rstcs: array of struct reset_control_bulk_data with reset controls set
492 *
493 * Assert the reset lines for all provided reset controls, in order.
494 * If an assertion fails, already asserted resets are deasserted again.
495 *
496 * See also: reset_control_assert()
497 */
498int reset_control_bulk_assert(int num_rstcs,
499 struct reset_control_bulk_data *rstcs)
500{
501 int ret, i;
502
503 for (i = 0; i < num_rstcs; i++) {
504 ret = reset_control_assert(rstcs[i].rstc);
505 if (ret)
506 goto err;
507 }
508
509 return 0;
510
511err:
512 while (i--)
513 reset_control_deassert(rstcs[i].rstc);
514 return ret;
515}
516EXPORT_SYMBOL_GPL(reset_control_bulk_assert);
517
518/**
519 * reset_control_deassert - deasserts the reset line
520 * @rstc: reset controller
521 *
522 * After calling this function, the reset is guaranteed to be deasserted.
523 * Consumers must not use reset_control_reset on shared reset lines when
524 * reset_control_(de)assert has been used.
525 *
526 * If rstc is NULL it is an optional reset and the function will just
527 * return 0.
528 */
529int reset_control_deassert(struct reset_control *rstc)
530{
531 if (!rstc)
532 return 0;
533
534 if (WARN_ON(IS_ERR(rstc)))
535 return -EINVAL;
536
537 if (reset_control_is_array(rstc))
538 return reset_control_array_deassert(rstc_to_array(rstc));
539
540 if (rstc->shared) {
541 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
542 return -EINVAL;
543
544 if (atomic_inc_return(&rstc->deassert_count) != 1)
545 return 0;
546 } else {
547 if (!rstc->acquired) {
548 WARN(1, "reset %s (ID: %u) is not acquired\n",
549 rcdev_name(rstc->rcdev), rstc->id);
550 return -EPERM;
551 }
552 }
553
554 /*
555 * If the reset controller does not implement .deassert(), we assume
556 * that it handles self-deasserting reset lines via .reset(). In that
557 * case, the reset lines are deasserted by default. If that is not the
558 * case, the reset controller driver should implement .deassert() and
559 * return -ENOTSUPP.
560 */
561 if (!rstc->rcdev->ops->deassert)
562 return 0;
563
564 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
565}
566EXPORT_SYMBOL_GPL(reset_control_deassert);
567
568/**
569 * reset_control_bulk_deassert - deasserts the reset lines in reverse order
570 * @num_rstcs: number of entries in rstcs array
571 * @rstcs: array of struct reset_control_bulk_data with reset controls set
572 *
573 * Deassert the reset lines for all provided reset controls, in reverse order.
574 * If a deassertion fails, already deasserted resets are asserted again.
575 *
576 * See also: reset_control_deassert()
577 */
578int reset_control_bulk_deassert(int num_rstcs,
579 struct reset_control_bulk_data *rstcs)
580{
581 int ret, i;
582
583 for (i = num_rstcs - 1; i >= 0; i--) {
584 ret = reset_control_deassert(rstcs[i].rstc);
585 if (ret)
586 goto err;
587 }
588
589 return 0;
590
591err:
592 while (i < num_rstcs)
593 reset_control_assert(rstcs[i++].rstc);
594 return ret;
595}
596EXPORT_SYMBOL_GPL(reset_control_bulk_deassert);
597
598/**
599 * reset_control_status - returns a negative errno if not supported, a
600 * positive value if the reset line is asserted, or zero if the reset
601 * line is not asserted or if the desc is NULL (optional reset).
602 * @rstc: reset controller
603 */
604int reset_control_status(struct reset_control *rstc)
605{
606 if (!rstc)
607 return 0;
608
609 if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
610 return -EINVAL;
611
612 if (rstc->rcdev->ops->status)
613 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
614
615 return -ENOTSUPP;
616}
617EXPORT_SYMBOL_GPL(reset_control_status);
618
619/**
620 * reset_control_acquire() - acquires a reset control for exclusive use
621 * @rstc: reset control
622 *
623 * This is used to explicitly acquire a reset control for exclusive use. Note
624 * that exclusive resets are requested as acquired by default. In order for a
625 * second consumer to be able to control the reset, the first consumer has to
626 * release it first. Typically the easiest way to achieve this is to call the
627 * reset_control_get_exclusive_released() to obtain an instance of the reset
628 * control. Such reset controls are not acquired by default.
629 *
630 * Consumers implementing shared access to an exclusive reset need to follow
631 * a specific protocol in order to work together. Before consumers can change
632 * a reset they must acquire exclusive access using reset_control_acquire().
633 * After they are done operating the reset, they must release exclusive access
634 * with a call to reset_control_release(). Consumers are not granted exclusive
635 * access to the reset as long as another consumer hasn't released a reset.
636 *
637 * See also: reset_control_release()
638 */
639int reset_control_acquire(struct reset_control *rstc)
640{
641 struct reset_control *rc;
642
643 if (!rstc)
644 return 0;
645
646 if (WARN_ON(IS_ERR(rstc)))
647 return -EINVAL;
648
649 if (reset_control_is_array(rstc))
650 return reset_control_array_acquire(rstc_to_array(rstc));
651
652 mutex_lock(&reset_list_mutex);
653
654 if (rstc->acquired) {
655 mutex_unlock(&reset_list_mutex);
656 return 0;
657 }
658
659 list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
660 if (rstc != rc && rstc->id == rc->id) {
661 if (rc->acquired) {
662 mutex_unlock(&reset_list_mutex);
663 return -EBUSY;
664 }
665 }
666 }
667
668 rstc->acquired = true;
669
670 mutex_unlock(&reset_list_mutex);
671 return 0;
672}
673EXPORT_SYMBOL_GPL(reset_control_acquire);
674
675/**
676 * reset_control_bulk_acquire - acquires reset controls for exclusive use
677 * @num_rstcs: number of entries in rstcs array
678 * @rstcs: array of struct reset_control_bulk_data with reset controls set
679 *
680 * This is used to explicitly acquire reset controls requested with
681 * reset_control_bulk_get_exclusive_release() for temporary exclusive use.
682 *
683 * See also: reset_control_acquire(), reset_control_bulk_release()
684 */
685int reset_control_bulk_acquire(int num_rstcs,
686 struct reset_control_bulk_data *rstcs)
687{
688 int ret, i;
689
690 for (i = 0; i < num_rstcs; i++) {
691 ret = reset_control_acquire(rstcs[i].rstc);
692 if (ret)
693 goto err;
694 }
695
696 return 0;
697
698err:
699 while (i--)
700 reset_control_release(rstcs[i].rstc);
701 return ret;
702}
703EXPORT_SYMBOL_GPL(reset_control_bulk_acquire);
704
705/**
706 * reset_control_release() - releases exclusive access to a reset control
707 * @rstc: reset control
708 *
709 * Releases exclusive access right to a reset control previously obtained by a
710 * call to reset_control_acquire(). Until a consumer calls this function, no
711 * other consumers will be granted exclusive access.
712 *
713 * See also: reset_control_acquire()
714 */
715void reset_control_release(struct reset_control *rstc)
716{
717 if (!rstc || WARN_ON(IS_ERR(rstc)))
718 return;
719
720 if (reset_control_is_array(rstc))
721 reset_control_array_release(rstc_to_array(rstc));
722 else
723 rstc->acquired = false;
724}
725EXPORT_SYMBOL_GPL(reset_control_release);
726
727/**
728 * reset_control_bulk_release() - releases exclusive access to reset controls
729 * @num_rstcs: number of entries in rstcs array
730 * @rstcs: array of struct reset_control_bulk_data with reset controls set
731 *
732 * Releases exclusive access right to reset controls previously obtained by a
733 * call to reset_control_bulk_acquire().
734 *
735 * See also: reset_control_release(), reset_control_bulk_acquire()
736 */
737void reset_control_bulk_release(int num_rstcs,
738 struct reset_control_bulk_data *rstcs)
739{
740 int i;
741
742 for (i = 0; i < num_rstcs; i++)
743 reset_control_release(rstcs[i].rstc);
744}
745EXPORT_SYMBOL_GPL(reset_control_bulk_release);
746
747static struct reset_control *
748__reset_control_get_internal(struct reset_controller_dev *rcdev,
749 unsigned int index, bool shared, bool acquired)
750{
751 struct reset_control *rstc;
752
753 lockdep_assert_held(&reset_list_mutex);
754
755 list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
756 if (rstc->id == index) {
757 /*
758 * Allow creating a secondary exclusive reset_control
759 * that is initially not acquired for an already
760 * controlled reset line.
761 */
762 if (!rstc->shared && !shared && !acquired)
763 break;
764
765 if (WARN_ON(!rstc->shared || !shared))
766 return ERR_PTR(-EBUSY);
767
768 kref_get(&rstc->refcnt);
769 return rstc;
770 }
771 }
772
773 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
774 if (!rstc)
775 return ERR_PTR(-ENOMEM);
776
777 if (!try_module_get(rcdev->owner)) {
778 kfree(rstc);
779 return ERR_PTR(-ENODEV);
780 }
781
782 rstc->rcdev = rcdev;
783 list_add(&rstc->list, &rcdev->reset_control_head);
784 rstc->id = index;
785 kref_init(&rstc->refcnt);
786 rstc->acquired = acquired;
787 rstc->shared = shared;
788
789 return rstc;
790}
791
792static void __reset_control_release(struct kref *kref)
793{
794 struct reset_control *rstc = container_of(kref, struct reset_control,
795 refcnt);
796
797 lockdep_assert_held(&reset_list_mutex);
798
799 module_put(rstc->rcdev->owner);
800
801 list_del(&rstc->list);
802 kfree(rstc);
803}
804
805static void __reset_control_put_internal(struct reset_control *rstc)
806{
807 lockdep_assert_held(&reset_list_mutex);
808
809 kref_put(&rstc->refcnt, __reset_control_release);
810}
811
812struct reset_control *
813__of_reset_control_get(struct device_node *node, const char *id, int index,
814 bool shared, bool optional, bool acquired)
815{
816 struct reset_control *rstc;
817 struct reset_controller_dev *r, *rcdev;
818 struct of_phandle_args args;
819 int rstc_id;
820 int ret;
821
822 if (!node)
823 return ERR_PTR(-EINVAL);
824
825 if (id) {
826 index = of_property_match_string(node,
827 "reset-names", id);
828 if (index == -EILSEQ)
829 return ERR_PTR(index);
830 if (index < 0)
831 return optional ? NULL : ERR_PTR(-ENOENT);
832 }
833
834 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
835 index, &args);
836 if (ret == -EINVAL)
837 return ERR_PTR(ret);
838 if (ret)
839 return optional ? NULL : ERR_PTR(ret);
840
841 mutex_lock(&reset_list_mutex);
842 rcdev = NULL;
843 list_for_each_entry(r, &reset_controller_list, list) {
844 if (args.np == r->of_node) {
845 rcdev = r;
846 break;
847 }
848 }
849
850 if (!rcdev) {
851 rstc = ERR_PTR(-EPROBE_DEFER);
852 goto out;
853 }
854
855 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
856 rstc = ERR_PTR(-EINVAL);
857 goto out;
858 }
859
860 rstc_id = rcdev->of_xlate(rcdev, &args);
861 if (rstc_id < 0) {
862 rstc = ERR_PTR(rstc_id);
863 goto out;
864 }
865
866 /* reset_list_mutex also protects the rcdev's reset_control list */
867 rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
868
869out:
870 mutex_unlock(&reset_list_mutex);
871 of_node_put(args.np);
872
873 return rstc;
874}
875EXPORT_SYMBOL_GPL(__of_reset_control_get);
876
877static struct reset_controller_dev *
878__reset_controller_by_name(const char *name)
879{
880 struct reset_controller_dev *rcdev;
881
882 lockdep_assert_held(&reset_list_mutex);
883
884 list_for_each_entry(rcdev, &reset_controller_list, list) {
885 if (!rcdev->dev)
886 continue;
887
888 if (!strcmp(name, dev_name(rcdev->dev)))
889 return rcdev;
890 }
891
892 return NULL;
893}
894
895static struct reset_control *
896__reset_control_get_from_lookup(struct device *dev, const char *con_id,
897 bool shared, bool optional, bool acquired)
898{
899 const struct reset_control_lookup *lookup;
900 struct reset_controller_dev *rcdev;
901 const char *dev_id = dev_name(dev);
902 struct reset_control *rstc = NULL;
903
904 mutex_lock(&reset_lookup_mutex);
905
906 list_for_each_entry(lookup, &reset_lookup_list, list) {
907 if (strcmp(lookup->dev_id, dev_id))
908 continue;
909
910 if ((!con_id && !lookup->con_id) ||
911 ((con_id && lookup->con_id) &&
912 !strcmp(con_id, lookup->con_id))) {
913 mutex_lock(&reset_list_mutex);
914 rcdev = __reset_controller_by_name(lookup->provider);
915 if (!rcdev) {
916 mutex_unlock(&reset_list_mutex);
917 mutex_unlock(&reset_lookup_mutex);
918 /* Reset provider may not be ready yet. */
919 return ERR_PTR(-EPROBE_DEFER);
920 }
921
922 rstc = __reset_control_get_internal(rcdev,
923 lookup->index,
924 shared, acquired);
925 mutex_unlock(&reset_list_mutex);
926 break;
927 }
928 }
929
930 mutex_unlock(&reset_lookup_mutex);
931
932 if (!rstc)
933 return optional ? NULL : ERR_PTR(-ENOENT);
934
935 return rstc;
936}
937
938struct reset_control *__reset_control_get(struct device *dev, const char *id,
939 int index, bool shared, bool optional,
940 bool acquired)
941{
942 if (WARN_ON(shared && acquired))
943 return ERR_PTR(-EINVAL);
944
945 if (dev->of_node)
946 return __of_reset_control_get(dev->of_node, id, index, shared,
947 optional, acquired);
948
949 return __reset_control_get_from_lookup(dev, id, shared, optional,
950 acquired);
951}
952EXPORT_SYMBOL_GPL(__reset_control_get);
953
954int __reset_control_bulk_get(struct device *dev, int num_rstcs,
955 struct reset_control_bulk_data *rstcs,
956 bool shared, bool optional, bool acquired)
957{
958 int ret, i;
959
960 for (i = 0; i < num_rstcs; i++) {
961 rstcs[i].rstc = __reset_control_get(dev, rstcs[i].id, 0,
962 shared, optional, acquired);
963 if (IS_ERR(rstcs[i].rstc)) {
964 ret = PTR_ERR(rstcs[i].rstc);
965 goto err;
966 }
967 }
968
969 return 0;
970
971err:
972 mutex_lock(&reset_list_mutex);
973 while (i--)
974 __reset_control_put_internal(rstcs[i].rstc);
975 mutex_unlock(&reset_list_mutex);
976 return ret;
977}
978EXPORT_SYMBOL_GPL(__reset_control_bulk_get);
979
980static void reset_control_array_put(struct reset_control_array *resets)
981{
982 int i;
983
984 mutex_lock(&reset_list_mutex);
985 for (i = 0; i < resets->num_rstcs; i++)
986 __reset_control_put_internal(resets->rstc[i]);
987 mutex_unlock(&reset_list_mutex);
988 kfree(resets);
989}
990
991/**
992 * reset_control_put - free the reset controller
993 * @rstc: reset controller
994 */
995void reset_control_put(struct reset_control *rstc)
996{
997 if (IS_ERR_OR_NULL(rstc))
998 return;
999
1000 if (reset_control_is_array(rstc)) {
1001 reset_control_array_put(rstc_to_array(rstc));
1002 return;
1003 }
1004
1005 mutex_lock(&reset_list_mutex);
1006 __reset_control_put_internal(rstc);
1007 mutex_unlock(&reset_list_mutex);
1008}
1009EXPORT_SYMBOL_GPL(reset_control_put);
1010
1011/**
1012 * reset_control_bulk_put - free the reset controllers
1013 * @num_rstcs: number of entries in rstcs array
1014 * @rstcs: array of struct reset_control_bulk_data with reset controls set
1015 */
1016void reset_control_bulk_put(int num_rstcs, struct reset_control_bulk_data *rstcs)
1017{
1018 mutex_lock(&reset_list_mutex);
1019 while (num_rstcs--) {
1020 if (IS_ERR_OR_NULL(rstcs[num_rstcs].rstc))
1021 continue;
1022 __reset_control_put_internal(rstcs[num_rstcs].rstc);
1023 }
1024 mutex_unlock(&reset_list_mutex);
1025}
1026EXPORT_SYMBOL_GPL(reset_control_bulk_put);
1027
1028static void devm_reset_control_release(struct device *dev, void *res)
1029{
1030 reset_control_put(*(struct reset_control **)res);
1031}
1032
1033struct reset_control *
1034__devm_reset_control_get(struct device *dev, const char *id, int index,
1035 bool shared, bool optional, bool acquired)
1036{
1037 struct reset_control **ptr, *rstc;
1038
1039 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
1040 GFP_KERNEL);
1041 if (!ptr)
1042 return ERR_PTR(-ENOMEM);
1043
1044 rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
1045 if (IS_ERR_OR_NULL(rstc)) {
1046 devres_free(ptr);
1047 return rstc;
1048 }
1049
1050 *ptr = rstc;
1051 devres_add(dev, ptr);
1052
1053 return rstc;
1054}
1055EXPORT_SYMBOL_GPL(__devm_reset_control_get);
1056
1057struct reset_control_bulk_devres {
1058 int num_rstcs;
1059 struct reset_control_bulk_data *rstcs;
1060};
1061
1062static void devm_reset_control_bulk_release(struct device *dev, void *res)
1063{
1064 struct reset_control_bulk_devres *devres = res;
1065
1066 reset_control_bulk_put(devres->num_rstcs, devres->rstcs);
1067}
1068
1069int __devm_reset_control_bulk_get(struct device *dev, int num_rstcs,
1070 struct reset_control_bulk_data *rstcs,
1071 bool shared, bool optional, bool acquired)
1072{
1073 struct reset_control_bulk_devres *ptr;
1074 int ret;
1075
1076 ptr = devres_alloc(devm_reset_control_bulk_release, sizeof(*ptr),
1077 GFP_KERNEL);
1078 if (!ptr)
1079 return -ENOMEM;
1080
1081 ret = __reset_control_bulk_get(dev, num_rstcs, rstcs, shared, optional, acquired);
1082 if (ret < 0) {
1083 devres_free(ptr);
1084 return ret;
1085 }
1086
1087 ptr->num_rstcs = num_rstcs;
1088 ptr->rstcs = rstcs;
1089 devres_add(dev, ptr);
1090
1091 return 0;
1092}
1093EXPORT_SYMBOL_GPL(__devm_reset_control_bulk_get);
1094
1095/**
1096 * __device_reset - find reset controller associated with the device
1097 * and perform reset
1098 * @dev: device to be reset by the controller
1099 * @optional: whether it is optional to reset the device
1100 *
1101 * Convenience wrapper for __reset_control_get() and reset_control_reset().
1102 * This is useful for the common case of devices with single, dedicated reset
1103 * lines.
1104 */
1105int __device_reset(struct device *dev, bool optional)
1106{
1107 struct reset_control *rstc;
1108 int ret;
1109
1110 rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
1111 if (IS_ERR(rstc))
1112 return PTR_ERR(rstc);
1113
1114 ret = reset_control_reset(rstc);
1115
1116 reset_control_put(rstc);
1117
1118 return ret;
1119}
1120EXPORT_SYMBOL_GPL(__device_reset);
1121
1122/*
1123 * APIs to manage an array of reset controls.
1124 */
1125
1126/**
1127 * of_reset_control_get_count - Count number of resets available with a device
1128 *
1129 * @node: device node that contains 'resets'.
1130 *
1131 * Returns positive reset count on success, or error number on failure and
1132 * on count being zero.
1133 */
1134static int of_reset_control_get_count(struct device_node *node)
1135{
1136 int count;
1137
1138 if (!node)
1139 return -EINVAL;
1140
1141 count = of_count_phandle_with_args(node, "resets", "#reset-cells");
1142 if (count == 0)
1143 count = -ENOENT;
1144
1145 return count;
1146}
1147
1148/**
1149 * of_reset_control_array_get - Get a list of reset controls using
1150 * device node.
1151 *
1152 * @np: device node for the device that requests the reset controls array
1153 * @shared: whether reset controls are shared or not
1154 * @optional: whether it is optional to get the reset controls
1155 * @acquired: only one reset control may be acquired for a given controller
1156 * and ID
1157 *
1158 * Returns pointer to allocated reset_control on success or error on failure
1159 */
1160struct reset_control *
1161of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
1162 bool acquired)
1163{
1164 struct reset_control_array *resets;
1165 struct reset_control *rstc;
1166 int num, i;
1167
1168 num = of_reset_control_get_count(np);
1169 if (num < 0)
1170 return optional ? NULL : ERR_PTR(num);
1171
1172 resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
1173 if (!resets)
1174 return ERR_PTR(-ENOMEM);
1175
1176 for (i = 0; i < num; i++) {
1177 rstc = __of_reset_control_get(np, NULL, i, shared, optional,
1178 acquired);
1179 if (IS_ERR(rstc))
1180 goto err_rst;
1181 resets->rstc[i] = rstc;
1182 }
1183 resets->num_rstcs = num;
1184 resets->base.array = true;
1185
1186 return &resets->base;
1187
1188err_rst:
1189 mutex_lock(&reset_list_mutex);
1190 while (--i >= 0)
1191 __reset_control_put_internal(resets->rstc[i]);
1192 mutex_unlock(&reset_list_mutex);
1193
1194 kfree(resets);
1195
1196 return rstc;
1197}
1198EXPORT_SYMBOL_GPL(of_reset_control_array_get);
1199
1200/**
1201 * devm_reset_control_array_get - Resource managed reset control array get
1202 *
1203 * @dev: device that requests the list of reset controls
1204 * @shared: whether reset controls are shared or not
1205 * @optional: whether it is optional to get the reset controls
1206 *
1207 * The reset control array APIs are intended for a list of resets
1208 * that just have to be asserted or deasserted, without any
1209 * requirements on the order.
1210 *
1211 * Returns pointer to allocated reset_control on success or error on failure
1212 */
1213struct reset_control *
1214devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
1215{
1216 struct reset_control **ptr, *rstc;
1217
1218 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
1219 GFP_KERNEL);
1220 if (!ptr)
1221 return ERR_PTR(-ENOMEM);
1222
1223 rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
1224 if (IS_ERR_OR_NULL(rstc)) {
1225 devres_free(ptr);
1226 return rstc;
1227 }
1228
1229 *ptr = rstc;
1230 devres_add(dev, ptr);
1231
1232 return rstc;
1233}
1234EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
1235
1236static int reset_control_get_count_from_lookup(struct device *dev)
1237{
1238 const struct reset_control_lookup *lookup;
1239 const char *dev_id;
1240 int count = 0;
1241
1242 if (!dev)
1243 return -EINVAL;
1244
1245 dev_id = dev_name(dev);
1246 mutex_lock(&reset_lookup_mutex);
1247
1248 list_for_each_entry(lookup, &reset_lookup_list, list) {
1249 if (!strcmp(lookup->dev_id, dev_id))
1250 count++;
1251 }
1252
1253 mutex_unlock(&reset_lookup_mutex);
1254
1255 if (count == 0)
1256 count = -ENOENT;
1257
1258 return count;
1259}
1260
1261/**
1262 * reset_control_get_count - Count number of resets available with a device
1263 *
1264 * @dev: device for which to return the number of resets
1265 *
1266 * Returns positive reset count on success, or error number on failure and
1267 * on count being zero.
1268 */
1269int reset_control_get_count(struct device *dev)
1270{
1271 if (dev->of_node)
1272 return of_reset_control_get_count(dev->of_node);
1273
1274 return reset_control_get_count_from_lookup(dev);
1275}
1276EXPORT_SYMBOL_GPL(reset_control_get_count);