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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/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[] __counted_by(num_rstcs);
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 if (IS_ERR_OR_NULL(rstc))
811 return;
812
813 kref_put(&rstc->refcnt, __reset_control_release);
814}
815
816struct reset_control *
817__of_reset_control_get(struct device_node *node, const char *id, int index,
818 bool shared, bool optional, bool acquired)
819{
820 struct reset_control *rstc;
821 struct reset_controller_dev *r, *rcdev;
822 struct of_phandle_args args;
823 int rstc_id;
824 int ret;
825
826 if (!node)
827 return ERR_PTR(-EINVAL);
828
829 if (id) {
830 index = of_property_match_string(node,
831 "reset-names", id);
832 if (index == -EILSEQ)
833 return ERR_PTR(index);
834 if (index < 0)
835 return optional ? NULL : ERR_PTR(-ENOENT);
836 }
837
838 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
839 index, &args);
840 if (ret == -EINVAL)
841 return ERR_PTR(ret);
842 if (ret)
843 return optional ? NULL : ERR_PTR(ret);
844
845 mutex_lock(&reset_list_mutex);
846 rcdev = NULL;
847 list_for_each_entry(r, &reset_controller_list, list) {
848 if (args.np == r->of_node) {
849 rcdev = r;
850 break;
851 }
852 }
853
854 if (!rcdev) {
855 rstc = ERR_PTR(-EPROBE_DEFER);
856 goto out;
857 }
858
859 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
860 rstc = ERR_PTR(-EINVAL);
861 goto out;
862 }
863
864 rstc_id = rcdev->of_xlate(rcdev, &args);
865 if (rstc_id < 0) {
866 rstc = ERR_PTR(rstc_id);
867 goto out;
868 }
869
870 /* reset_list_mutex also protects the rcdev's reset_control list */
871 rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
872
873out:
874 mutex_unlock(&reset_list_mutex);
875 of_node_put(args.np);
876
877 return rstc;
878}
879EXPORT_SYMBOL_GPL(__of_reset_control_get);
880
881static struct reset_controller_dev *
882__reset_controller_by_name(const char *name)
883{
884 struct reset_controller_dev *rcdev;
885
886 lockdep_assert_held(&reset_list_mutex);
887
888 list_for_each_entry(rcdev, &reset_controller_list, list) {
889 if (!rcdev->dev)
890 continue;
891
892 if (!strcmp(name, dev_name(rcdev->dev)))
893 return rcdev;
894 }
895
896 return NULL;
897}
898
899static struct reset_control *
900__reset_control_get_from_lookup(struct device *dev, const char *con_id,
901 bool shared, bool optional, bool acquired)
902{
903 const struct reset_control_lookup *lookup;
904 struct reset_controller_dev *rcdev;
905 const char *dev_id = dev_name(dev);
906 struct reset_control *rstc = NULL;
907
908 mutex_lock(&reset_lookup_mutex);
909
910 list_for_each_entry(lookup, &reset_lookup_list, list) {
911 if (strcmp(lookup->dev_id, dev_id))
912 continue;
913
914 if ((!con_id && !lookup->con_id) ||
915 ((con_id && lookup->con_id) &&
916 !strcmp(con_id, lookup->con_id))) {
917 mutex_lock(&reset_list_mutex);
918 rcdev = __reset_controller_by_name(lookup->provider);
919 if (!rcdev) {
920 mutex_unlock(&reset_list_mutex);
921 mutex_unlock(&reset_lookup_mutex);
922 /* Reset provider may not be ready yet. */
923 return ERR_PTR(-EPROBE_DEFER);
924 }
925
926 rstc = __reset_control_get_internal(rcdev,
927 lookup->index,
928 shared, acquired);
929 mutex_unlock(&reset_list_mutex);
930 break;
931 }
932 }
933
934 mutex_unlock(&reset_lookup_mutex);
935
936 if (!rstc)
937 return optional ? NULL : ERR_PTR(-ENOENT);
938
939 return rstc;
940}
941
942struct reset_control *__reset_control_get(struct device *dev, const char *id,
943 int index, bool shared, bool optional,
944 bool acquired)
945{
946 if (WARN_ON(shared && acquired))
947 return ERR_PTR(-EINVAL);
948
949 if (dev->of_node)
950 return __of_reset_control_get(dev->of_node, id, index, shared,
951 optional, acquired);
952
953 return __reset_control_get_from_lookup(dev, id, shared, optional,
954 acquired);
955}
956EXPORT_SYMBOL_GPL(__reset_control_get);
957
958int __reset_control_bulk_get(struct device *dev, int num_rstcs,
959 struct reset_control_bulk_data *rstcs,
960 bool shared, bool optional, bool acquired)
961{
962 int ret, i;
963
964 for (i = 0; i < num_rstcs; i++) {
965 rstcs[i].rstc = __reset_control_get(dev, rstcs[i].id, 0,
966 shared, optional, acquired);
967 if (IS_ERR(rstcs[i].rstc)) {
968 ret = PTR_ERR(rstcs[i].rstc);
969 goto err;
970 }
971 }
972
973 return 0;
974
975err:
976 mutex_lock(&reset_list_mutex);
977 while (i--)
978 __reset_control_put_internal(rstcs[i].rstc);
979 mutex_unlock(&reset_list_mutex);
980 return ret;
981}
982EXPORT_SYMBOL_GPL(__reset_control_bulk_get);
983
984static void reset_control_array_put(struct reset_control_array *resets)
985{
986 int i;
987
988 mutex_lock(&reset_list_mutex);
989 for (i = 0; i < resets->num_rstcs; i++)
990 __reset_control_put_internal(resets->rstc[i]);
991 mutex_unlock(&reset_list_mutex);
992 kfree(resets);
993}
994
995/**
996 * reset_control_put - free the reset controller
997 * @rstc: reset controller
998 */
999void reset_control_put(struct reset_control *rstc)
1000{
1001 if (IS_ERR_OR_NULL(rstc))
1002 return;
1003
1004 if (reset_control_is_array(rstc)) {
1005 reset_control_array_put(rstc_to_array(rstc));
1006 return;
1007 }
1008
1009 mutex_lock(&reset_list_mutex);
1010 __reset_control_put_internal(rstc);
1011 mutex_unlock(&reset_list_mutex);
1012}
1013EXPORT_SYMBOL_GPL(reset_control_put);
1014
1015/**
1016 * reset_control_bulk_put - free the reset controllers
1017 * @num_rstcs: number of entries in rstcs array
1018 * @rstcs: array of struct reset_control_bulk_data with reset controls set
1019 */
1020void reset_control_bulk_put(int num_rstcs, struct reset_control_bulk_data *rstcs)
1021{
1022 mutex_lock(&reset_list_mutex);
1023 while (num_rstcs--)
1024 __reset_control_put_internal(rstcs[num_rstcs].rstc);
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 resets->num_rstcs = num;
1189
1190 for (i = 0; i < num; i++) {
1191 rstc = __of_reset_control_get(np, NULL, i, shared, optional,
1192 acquired);
1193 if (IS_ERR(rstc))
1194 goto err_rst;
1195 resets->rstc[i] = rstc;
1196 }
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);
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 simple translation function should be used for reset controllers
81 * with 1:1 mapping, where reset lines can be indexed by number without gaps.
82 */
83static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
84 const struct of_phandle_args *reset_spec)
85{
86 if (reset_spec->args[0] >= rcdev->nr_resets)
87 return -EINVAL;
88
89 return reset_spec->args[0];
90}
91
92/**
93 * reset_controller_register - register a reset controller device
94 * @rcdev: a pointer to the initialized reset controller device
95 */
96int reset_controller_register(struct reset_controller_dev *rcdev)
97{
98 if (!rcdev->of_xlate) {
99 rcdev->of_reset_n_cells = 1;
100 rcdev->of_xlate = of_reset_simple_xlate;
101 }
102
103 INIT_LIST_HEAD(&rcdev->reset_control_head);
104
105 mutex_lock(&reset_list_mutex);
106 list_add(&rcdev->list, &reset_controller_list);
107 mutex_unlock(&reset_list_mutex);
108
109 return 0;
110}
111EXPORT_SYMBOL_GPL(reset_controller_register);
112
113/**
114 * reset_controller_unregister - unregister a reset controller device
115 * @rcdev: a pointer to the reset controller device
116 */
117void reset_controller_unregister(struct reset_controller_dev *rcdev)
118{
119 mutex_lock(&reset_list_mutex);
120 list_del(&rcdev->list);
121 mutex_unlock(&reset_list_mutex);
122}
123EXPORT_SYMBOL_GPL(reset_controller_unregister);
124
125static void devm_reset_controller_release(struct device *dev, void *res)
126{
127 reset_controller_unregister(*(struct reset_controller_dev **)res);
128}
129
130/**
131 * devm_reset_controller_register - resource managed reset_controller_register()
132 * @dev: device that is registering this reset controller
133 * @rcdev: a pointer to the initialized reset controller device
134 *
135 * Managed reset_controller_register(). For reset controllers registered by
136 * this function, reset_controller_unregister() is automatically called on
137 * driver detach. See reset_controller_register() for more information.
138 */
139int devm_reset_controller_register(struct device *dev,
140 struct reset_controller_dev *rcdev)
141{
142 struct reset_controller_dev **rcdevp;
143 int ret;
144
145 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
146 GFP_KERNEL);
147 if (!rcdevp)
148 return -ENOMEM;
149
150 ret = reset_controller_register(rcdev);
151 if (!ret) {
152 *rcdevp = rcdev;
153 devres_add(dev, rcdevp);
154 } else {
155 devres_free(rcdevp);
156 }
157
158 return ret;
159}
160EXPORT_SYMBOL_GPL(devm_reset_controller_register);
161
162/**
163 * reset_controller_add_lookup - register a set of lookup entries
164 * @lookup: array of reset lookup entries
165 * @num_entries: number of entries in the lookup array
166 */
167void reset_controller_add_lookup(struct reset_control_lookup *lookup,
168 unsigned int num_entries)
169{
170 struct reset_control_lookup *entry;
171 unsigned int i;
172
173 mutex_lock(&reset_lookup_mutex);
174 for (i = 0; i < num_entries; i++) {
175 entry = &lookup[i];
176
177 if (!entry->dev_id || !entry->provider) {
178 pr_warn("%s(): reset lookup entry badly specified, skipping\n",
179 __func__);
180 continue;
181 }
182
183 list_add_tail(&entry->list, &reset_lookup_list);
184 }
185 mutex_unlock(&reset_lookup_mutex);
186}
187EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
188
189static inline struct reset_control_array *
190rstc_to_array(struct reset_control *rstc) {
191 return container_of(rstc, struct reset_control_array, base);
192}
193
194static int reset_control_array_reset(struct reset_control_array *resets)
195{
196 int ret, i;
197
198 for (i = 0; i < resets->num_rstcs; i++) {
199 ret = reset_control_reset(resets->rstc[i]);
200 if (ret)
201 return ret;
202 }
203
204 return 0;
205}
206
207static int reset_control_array_assert(struct reset_control_array *resets)
208{
209 int ret, i;
210
211 for (i = 0; i < resets->num_rstcs; i++) {
212 ret = reset_control_assert(resets->rstc[i]);
213 if (ret)
214 goto err;
215 }
216
217 return 0;
218
219err:
220 while (i--)
221 reset_control_deassert(resets->rstc[i]);
222 return ret;
223}
224
225static int reset_control_array_deassert(struct reset_control_array *resets)
226{
227 int ret, i;
228
229 for (i = 0; i < resets->num_rstcs; i++) {
230 ret = reset_control_deassert(resets->rstc[i]);
231 if (ret)
232 goto err;
233 }
234
235 return 0;
236
237err:
238 while (i--)
239 reset_control_assert(resets->rstc[i]);
240 return ret;
241}
242
243static int reset_control_array_acquire(struct reset_control_array *resets)
244{
245 unsigned int i;
246 int err;
247
248 for (i = 0; i < resets->num_rstcs; i++) {
249 err = reset_control_acquire(resets->rstc[i]);
250 if (err < 0)
251 goto release;
252 }
253
254 return 0;
255
256release:
257 while (i--)
258 reset_control_release(resets->rstc[i]);
259
260 return err;
261}
262
263static void reset_control_array_release(struct reset_control_array *resets)
264{
265 unsigned int i;
266
267 for (i = 0; i < resets->num_rstcs; i++)
268 reset_control_release(resets->rstc[i]);
269}
270
271static inline bool reset_control_is_array(struct reset_control *rstc)
272{
273 return rstc->array;
274}
275
276/**
277 * reset_control_reset - reset the controlled device
278 * @rstc: reset controller
279 *
280 * On a shared reset line the actual reset pulse is only triggered once for the
281 * lifetime of the reset_control instance: for all but the first caller this is
282 * a no-op.
283 * Consumers must not use reset_control_(de)assert on shared reset lines when
284 * reset_control_reset has been used.
285 *
286 * If rstc is NULL it is an optional reset and the function will just
287 * return 0.
288 */
289int reset_control_reset(struct reset_control *rstc)
290{
291 int ret;
292
293 if (!rstc)
294 return 0;
295
296 if (WARN_ON(IS_ERR(rstc)))
297 return -EINVAL;
298
299 if (reset_control_is_array(rstc))
300 return reset_control_array_reset(rstc_to_array(rstc));
301
302 if (!rstc->rcdev->ops->reset)
303 return -ENOTSUPP;
304
305 if (rstc->shared) {
306 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
307 return -EINVAL;
308
309 if (atomic_inc_return(&rstc->triggered_count) != 1)
310 return 0;
311 } else {
312 if (!rstc->acquired)
313 return -EPERM;
314 }
315
316 ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
317 if (rstc->shared && ret)
318 atomic_dec(&rstc->triggered_count);
319
320 return ret;
321}
322EXPORT_SYMBOL_GPL(reset_control_reset);
323
324/**
325 * reset_control_assert - asserts the reset line
326 * @rstc: reset controller
327 *
328 * Calling this on an exclusive reset controller guarantees that the reset
329 * will be asserted. When called on a shared reset controller the line may
330 * still be deasserted, as long as other users keep it so.
331 *
332 * For shared reset controls a driver cannot expect the hw's registers and
333 * internal state to be reset, but must be prepared for this to happen.
334 * Consumers must not use reset_control_reset on shared reset lines when
335 * reset_control_(de)assert has been used.
336 * return 0.
337 *
338 * If rstc is NULL it is an optional reset and the function will just
339 * return 0.
340 */
341int reset_control_assert(struct reset_control *rstc)
342{
343 if (!rstc)
344 return 0;
345
346 if (WARN_ON(IS_ERR(rstc)))
347 return -EINVAL;
348
349 if (reset_control_is_array(rstc))
350 return reset_control_array_assert(rstc_to_array(rstc));
351
352 if (rstc->shared) {
353 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
354 return -EINVAL;
355
356 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
357 return -EINVAL;
358
359 if (atomic_dec_return(&rstc->deassert_count) != 0)
360 return 0;
361
362 /*
363 * Shared reset controls allow the reset line to be in any state
364 * after this call, so doing nothing is a valid option.
365 */
366 if (!rstc->rcdev->ops->assert)
367 return 0;
368 } else {
369 /*
370 * If the reset controller does not implement .assert(), there
371 * is no way to guarantee that the reset line is asserted after
372 * this call.
373 */
374 if (!rstc->rcdev->ops->assert)
375 return -ENOTSUPP;
376
377 if (!rstc->acquired) {
378 WARN(1, "reset %s (ID: %u) is not acquired\n",
379 rcdev_name(rstc->rcdev), rstc->id);
380 return -EPERM;
381 }
382 }
383
384 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
385}
386EXPORT_SYMBOL_GPL(reset_control_assert);
387
388/**
389 * reset_control_deassert - deasserts the reset line
390 * @rstc: reset controller
391 *
392 * After calling this function, the reset is guaranteed to be deasserted.
393 * Consumers must not use reset_control_reset on shared reset lines when
394 * reset_control_(de)assert has been used.
395 * return 0.
396 *
397 * If rstc is NULL it is an optional reset and the function will just
398 * return 0.
399 */
400int reset_control_deassert(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_deassert(rstc_to_array(rstc));
410
411 if (rstc->shared) {
412 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
413 return -EINVAL;
414
415 if (atomic_inc_return(&rstc->deassert_count) != 1)
416 return 0;
417 } else {
418 if (!rstc->acquired) {
419 WARN(1, "reset %s (ID: %u) is not acquired\n",
420 rcdev_name(rstc->rcdev), rstc->id);
421 return -EPERM;
422 }
423 }
424
425 /*
426 * If the reset controller does not implement .deassert(), we assume
427 * that it handles self-deasserting reset lines via .reset(). In that
428 * case, the reset lines are deasserted by default. If that is not the
429 * case, the reset controller driver should implement .deassert() and
430 * return -ENOTSUPP.
431 */
432 if (!rstc->rcdev->ops->deassert)
433 return 0;
434
435 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
436}
437EXPORT_SYMBOL_GPL(reset_control_deassert);
438
439/**
440 * reset_control_status - returns a negative errno if not supported, a
441 * positive value if the reset line is asserted, or zero if the reset
442 * line is not asserted or if the desc is NULL (optional reset).
443 * @rstc: reset controller
444 */
445int reset_control_status(struct reset_control *rstc)
446{
447 if (!rstc)
448 return 0;
449
450 if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
451 return -EINVAL;
452
453 if (rstc->rcdev->ops->status)
454 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
455
456 return -ENOTSUPP;
457}
458EXPORT_SYMBOL_GPL(reset_control_status);
459
460/**
461 * reset_control_acquire() - acquires a reset control for exclusive use
462 * @rstc: reset control
463 *
464 * This is used to explicitly acquire a reset control for exclusive use. Note
465 * that exclusive resets are requested as acquired by default. In order for a
466 * second consumer to be able to control the reset, the first consumer has to
467 * release it first. Typically the easiest way to achieve this is to call the
468 * reset_control_get_exclusive_released() to obtain an instance of the reset
469 * control. Such reset controls are not acquired by default.
470 *
471 * Consumers implementing shared access to an exclusive reset need to follow
472 * a specific protocol in order to work together. Before consumers can change
473 * a reset they must acquire exclusive access using reset_control_acquire().
474 * After they are done operating the reset, they must release exclusive access
475 * with a call to reset_control_release(). Consumers are not granted exclusive
476 * access to the reset as long as another consumer hasn't released a reset.
477 *
478 * See also: reset_control_release()
479 */
480int reset_control_acquire(struct reset_control *rstc)
481{
482 struct reset_control *rc;
483
484 if (!rstc)
485 return 0;
486
487 if (WARN_ON(IS_ERR(rstc)))
488 return -EINVAL;
489
490 if (reset_control_is_array(rstc))
491 return reset_control_array_acquire(rstc_to_array(rstc));
492
493 mutex_lock(&reset_list_mutex);
494
495 if (rstc->acquired) {
496 mutex_unlock(&reset_list_mutex);
497 return 0;
498 }
499
500 list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
501 if (rstc != rc && rstc->id == rc->id) {
502 if (rc->acquired) {
503 mutex_unlock(&reset_list_mutex);
504 return -EBUSY;
505 }
506 }
507 }
508
509 rstc->acquired = true;
510
511 mutex_unlock(&reset_list_mutex);
512 return 0;
513}
514EXPORT_SYMBOL_GPL(reset_control_acquire);
515
516/**
517 * reset_control_release() - releases exclusive access to a reset control
518 * @rstc: reset control
519 *
520 * Releases exclusive access right to a reset control previously obtained by a
521 * call to reset_control_acquire(). Until a consumer calls this function, no
522 * other consumers will be granted exclusive access.
523 *
524 * See also: reset_control_acquire()
525 */
526void reset_control_release(struct reset_control *rstc)
527{
528 if (!rstc || WARN_ON(IS_ERR(rstc)))
529 return;
530
531 if (reset_control_is_array(rstc))
532 reset_control_array_release(rstc_to_array(rstc));
533 else
534 rstc->acquired = false;
535}
536EXPORT_SYMBOL_GPL(reset_control_release);
537
538static struct reset_control *__reset_control_get_internal(
539 struct reset_controller_dev *rcdev,
540 unsigned int index, bool shared, bool acquired)
541{
542 struct reset_control *rstc;
543
544 lockdep_assert_held(&reset_list_mutex);
545
546 list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
547 if (rstc->id == index) {
548 /*
549 * Allow creating a secondary exclusive reset_control
550 * that is initially not acquired for an already
551 * controlled reset line.
552 */
553 if (!rstc->shared && !shared && !acquired)
554 break;
555
556 if (WARN_ON(!rstc->shared || !shared))
557 return ERR_PTR(-EBUSY);
558
559 kref_get(&rstc->refcnt);
560 return rstc;
561 }
562 }
563
564 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
565 if (!rstc)
566 return ERR_PTR(-ENOMEM);
567
568 try_module_get(rcdev->owner);
569
570 rstc->rcdev = rcdev;
571 list_add(&rstc->list, &rcdev->reset_control_head);
572 rstc->id = index;
573 kref_init(&rstc->refcnt);
574 rstc->acquired = acquired;
575 rstc->shared = shared;
576
577 return rstc;
578}
579
580static void __reset_control_release(struct kref *kref)
581{
582 struct reset_control *rstc = container_of(kref, struct reset_control,
583 refcnt);
584
585 lockdep_assert_held(&reset_list_mutex);
586
587 module_put(rstc->rcdev->owner);
588
589 list_del(&rstc->list);
590 kfree(rstc);
591}
592
593static void __reset_control_put_internal(struct reset_control *rstc)
594{
595 lockdep_assert_held(&reset_list_mutex);
596
597 kref_put(&rstc->refcnt, __reset_control_release);
598}
599
600struct reset_control *__of_reset_control_get(struct device_node *node,
601 const char *id, int index, bool shared,
602 bool optional, bool acquired)
603{
604 struct reset_control *rstc;
605 struct reset_controller_dev *r, *rcdev;
606 struct of_phandle_args args;
607 int rstc_id;
608 int ret;
609
610 if (!node)
611 return ERR_PTR(-EINVAL);
612
613 if (id) {
614 index = of_property_match_string(node,
615 "reset-names", id);
616 if (index == -EILSEQ)
617 return ERR_PTR(index);
618 if (index < 0)
619 return optional ? NULL : ERR_PTR(-ENOENT);
620 }
621
622 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
623 index, &args);
624 if (ret == -EINVAL)
625 return ERR_PTR(ret);
626 if (ret)
627 return optional ? NULL : ERR_PTR(ret);
628
629 mutex_lock(&reset_list_mutex);
630 rcdev = NULL;
631 list_for_each_entry(r, &reset_controller_list, list) {
632 if (args.np == r->of_node) {
633 rcdev = r;
634 break;
635 }
636 }
637
638 if (!rcdev) {
639 rstc = ERR_PTR(-EPROBE_DEFER);
640 goto out;
641 }
642
643 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
644 rstc = ERR_PTR(-EINVAL);
645 goto out;
646 }
647
648 rstc_id = rcdev->of_xlate(rcdev, &args);
649 if (rstc_id < 0) {
650 rstc = ERR_PTR(rstc_id);
651 goto out;
652 }
653
654 /* reset_list_mutex also protects the rcdev's reset_control list */
655 rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
656
657out:
658 mutex_unlock(&reset_list_mutex);
659 of_node_put(args.np);
660
661 return rstc;
662}
663EXPORT_SYMBOL_GPL(__of_reset_control_get);
664
665static struct reset_controller_dev *
666__reset_controller_by_name(const char *name)
667{
668 struct reset_controller_dev *rcdev;
669
670 lockdep_assert_held(&reset_list_mutex);
671
672 list_for_each_entry(rcdev, &reset_controller_list, list) {
673 if (!rcdev->dev)
674 continue;
675
676 if (!strcmp(name, dev_name(rcdev->dev)))
677 return rcdev;
678 }
679
680 return NULL;
681}
682
683static struct reset_control *
684__reset_control_get_from_lookup(struct device *dev, const char *con_id,
685 bool shared, bool optional, bool acquired)
686{
687 const struct reset_control_lookup *lookup;
688 struct reset_controller_dev *rcdev;
689 const char *dev_id = dev_name(dev);
690 struct reset_control *rstc = NULL;
691
692 mutex_lock(&reset_lookup_mutex);
693
694 list_for_each_entry(lookup, &reset_lookup_list, list) {
695 if (strcmp(lookup->dev_id, dev_id))
696 continue;
697
698 if ((!con_id && !lookup->con_id) ||
699 ((con_id && lookup->con_id) &&
700 !strcmp(con_id, lookup->con_id))) {
701 mutex_lock(&reset_list_mutex);
702 rcdev = __reset_controller_by_name(lookup->provider);
703 if (!rcdev) {
704 mutex_unlock(&reset_list_mutex);
705 mutex_unlock(&reset_lookup_mutex);
706 /* Reset provider may not be ready yet. */
707 return ERR_PTR(-EPROBE_DEFER);
708 }
709
710 rstc = __reset_control_get_internal(rcdev,
711 lookup->index,
712 shared, acquired);
713 mutex_unlock(&reset_list_mutex);
714 break;
715 }
716 }
717
718 mutex_unlock(&reset_lookup_mutex);
719
720 if (!rstc)
721 return optional ? NULL : ERR_PTR(-ENOENT);
722
723 return rstc;
724}
725
726struct reset_control *__reset_control_get(struct device *dev, const char *id,
727 int index, bool shared, bool optional,
728 bool acquired)
729{
730 if (WARN_ON(shared && acquired))
731 return ERR_PTR(-EINVAL);
732
733 if (dev->of_node)
734 return __of_reset_control_get(dev->of_node, id, index, shared,
735 optional, acquired);
736
737 return __reset_control_get_from_lookup(dev, id, shared, optional,
738 acquired);
739}
740EXPORT_SYMBOL_GPL(__reset_control_get);
741
742static void reset_control_array_put(struct reset_control_array *resets)
743{
744 int i;
745
746 mutex_lock(&reset_list_mutex);
747 for (i = 0; i < resets->num_rstcs; i++)
748 __reset_control_put_internal(resets->rstc[i]);
749 mutex_unlock(&reset_list_mutex);
750 kfree(resets);
751}
752
753/**
754 * reset_control_put - free the reset controller
755 * @rstc: reset controller
756 */
757void reset_control_put(struct reset_control *rstc)
758{
759 if (IS_ERR_OR_NULL(rstc))
760 return;
761
762 if (reset_control_is_array(rstc)) {
763 reset_control_array_put(rstc_to_array(rstc));
764 return;
765 }
766
767 mutex_lock(&reset_list_mutex);
768 __reset_control_put_internal(rstc);
769 mutex_unlock(&reset_list_mutex);
770}
771EXPORT_SYMBOL_GPL(reset_control_put);
772
773static void devm_reset_control_release(struct device *dev, void *res)
774{
775 reset_control_put(*(struct reset_control **)res);
776}
777
778struct reset_control *__devm_reset_control_get(struct device *dev,
779 const char *id, int index, bool shared,
780 bool optional, bool acquired)
781{
782 struct reset_control **ptr, *rstc;
783
784 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
785 GFP_KERNEL);
786 if (!ptr)
787 return ERR_PTR(-ENOMEM);
788
789 rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
790 if (!IS_ERR(rstc)) {
791 *ptr = rstc;
792 devres_add(dev, ptr);
793 } else {
794 devres_free(ptr);
795 }
796
797 return rstc;
798}
799EXPORT_SYMBOL_GPL(__devm_reset_control_get);
800
801/**
802 * device_reset - find reset controller associated with the device
803 * and perform reset
804 * @dev: device to be reset by the controller
805 * @optional: whether it is optional to reset the device
806 *
807 * Convenience wrapper for __reset_control_get() and reset_control_reset().
808 * This is useful for the common case of devices with single, dedicated reset
809 * lines.
810 */
811int __device_reset(struct device *dev, bool optional)
812{
813 struct reset_control *rstc;
814 int ret;
815
816 rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
817 if (IS_ERR(rstc))
818 return PTR_ERR(rstc);
819
820 ret = reset_control_reset(rstc);
821
822 reset_control_put(rstc);
823
824 return ret;
825}
826EXPORT_SYMBOL_GPL(__device_reset);
827
828/*
829 * APIs to manage an array of reset controls.
830 */
831
832/**
833 * of_reset_control_get_count - Count number of resets available with a device
834 *
835 * @node: device node that contains 'resets'.
836 *
837 * Returns positive reset count on success, or error number on failure and
838 * on count being zero.
839 */
840static int of_reset_control_get_count(struct device_node *node)
841{
842 int count;
843
844 if (!node)
845 return -EINVAL;
846
847 count = of_count_phandle_with_args(node, "resets", "#reset-cells");
848 if (count == 0)
849 count = -ENOENT;
850
851 return count;
852}
853
854/**
855 * of_reset_control_array_get - Get a list of reset controls using
856 * device node.
857 *
858 * @np: device node for the device that requests the reset controls array
859 * @shared: whether reset controls are shared or not
860 * @optional: whether it is optional to get the reset controls
861 * @acquired: only one reset control may be acquired for a given controller
862 * and ID
863 *
864 * Returns pointer to allocated reset_control_array on success or
865 * error on failure
866 */
867struct reset_control *
868of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
869 bool acquired)
870{
871 struct reset_control_array *resets;
872 struct reset_control *rstc;
873 int num, i;
874
875 num = of_reset_control_get_count(np);
876 if (num < 0)
877 return optional ? NULL : ERR_PTR(num);
878
879 resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
880 if (!resets)
881 return ERR_PTR(-ENOMEM);
882
883 for (i = 0; i < num; i++) {
884 rstc = __of_reset_control_get(np, NULL, i, shared, optional,
885 acquired);
886 if (IS_ERR(rstc))
887 goto err_rst;
888 resets->rstc[i] = rstc;
889 }
890 resets->num_rstcs = num;
891 resets->base.array = true;
892
893 return &resets->base;
894
895err_rst:
896 mutex_lock(&reset_list_mutex);
897 while (--i >= 0)
898 __reset_control_put_internal(resets->rstc[i]);
899 mutex_unlock(&reset_list_mutex);
900
901 kfree(resets);
902
903 return rstc;
904}
905EXPORT_SYMBOL_GPL(of_reset_control_array_get);
906
907/**
908 * devm_reset_control_array_get - Resource managed reset control array get
909 *
910 * @dev: device that requests the list of reset controls
911 * @shared: whether reset controls are shared or not
912 * @optional: whether it is optional to get the reset controls
913 *
914 * The reset control array APIs are intended for a list of resets
915 * that just have to be asserted or deasserted, without any
916 * requirements on the order.
917 *
918 * Returns pointer to allocated reset_control_array on success or
919 * error on failure
920 */
921struct reset_control *
922devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
923{
924 struct reset_control **devres;
925 struct reset_control *rstc;
926
927 devres = devres_alloc(devm_reset_control_release, sizeof(*devres),
928 GFP_KERNEL);
929 if (!devres)
930 return ERR_PTR(-ENOMEM);
931
932 rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
933 if (IS_ERR(rstc)) {
934 devres_free(devres);
935 return rstc;
936 }
937
938 *devres = rstc;
939 devres_add(dev, devres);
940
941 return rstc;
942}
943EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
944
945static int reset_control_get_count_from_lookup(struct device *dev)
946{
947 const struct reset_control_lookup *lookup;
948 const char *dev_id;
949 int count = 0;
950
951 if (!dev)
952 return -EINVAL;
953
954 dev_id = dev_name(dev);
955 mutex_lock(&reset_lookup_mutex);
956
957 list_for_each_entry(lookup, &reset_lookup_list, list) {
958 if (!strcmp(lookup->dev_id, dev_id))
959 count++;
960 }
961
962 mutex_unlock(&reset_lookup_mutex);
963
964 if (count == 0)
965 count = -ENOENT;
966
967 return count;
968}
969
970/**
971 * reset_control_get_count - Count number of resets available with a device
972 *
973 * @dev: device for which to return the number of resets
974 *
975 * Returns positive reset count on success, or error number on failure and
976 * on count being zero.
977 */
978int reset_control_get_count(struct device *dev)
979{
980 if (dev->of_node)
981 return of_reset_control_get_count(dev->of_node);
982
983 return reset_control_get_count_from_lookup(dev);
984}
985EXPORT_SYMBOL_GPL(reset_control_get_count);