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