2 * Reset Controller framework
4 * Copyright 2013 Philipp Zabel, Pengutronix
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.
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>
19 #include <linux/reset.h>
20 #include <linux/reset-controller.h>
21 #include <linux/slab.h>
23 static DEFINE_MUTEX(reset_list_mutex);
24 static LIST_HEAD(reset_controller_list);
26 static DEFINE_MUTEX(reset_lookup_mutex);
27 static LIST_HEAD(reset_lookup_list);
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
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.
43 struct reset_control {
44 struct reset_controller_dev *rcdev;
45 struct list_head list;
50 atomic_t deassert_count;
51 atomic_t triggered_count;
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
60 struct reset_control_array {
61 struct reset_control base;
62 unsigned int num_rstcs;
63 struct reset_control *rstc[];
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)
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.
75 static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
76 const struct of_phandle_args *reset_spec)
78 if (reset_spec->args[0] >= rcdev->nr_resets)
81 return reset_spec->args[0];
85 * reset_controller_register - register a reset controller device
86 * @rcdev: a pointer to the initialized reset controller device
88 int reset_controller_register(struct reset_controller_dev *rcdev)
90 if (!rcdev->of_xlate) {
91 rcdev->of_reset_n_cells = 1;
92 rcdev->of_xlate = of_reset_simple_xlate;
95 INIT_LIST_HEAD(&rcdev->reset_control_head);
97 mutex_lock(&reset_list_mutex);
98 list_add(&rcdev->list, &reset_controller_list);
99 mutex_unlock(&reset_list_mutex);
103 EXPORT_SYMBOL_GPL(reset_controller_register);
106 * reset_controller_unregister - unregister a reset controller device
107 * @rcdev: a pointer to the reset controller device
109 void reset_controller_unregister(struct reset_controller_dev *rcdev)
111 mutex_lock(&reset_list_mutex);
112 list_del(&rcdev->list);
113 mutex_unlock(&reset_list_mutex);
115 EXPORT_SYMBOL_GPL(reset_controller_unregister);
117 static void devm_reset_controller_release(struct device *dev, void *res)
119 reset_controller_unregister(*(struct reset_controller_dev **)res);
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
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.
131 int devm_reset_controller_register(struct device *dev,
132 struct reset_controller_dev *rcdev)
134 struct reset_controller_dev **rcdevp;
137 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
142 ret = reset_controller_register(rcdev);
145 devres_add(dev, rcdevp);
152 EXPORT_SYMBOL_GPL(devm_reset_controller_register);
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
159 void reset_controller_add_lookup(struct reset_control_lookup *lookup,
160 unsigned int num_entries)
162 struct reset_control_lookup *entry;
165 mutex_lock(&reset_lookup_mutex);
166 for (i = 0; i < num_entries; i++) {
169 if (!entry->dev_id || !entry->provider) {
170 pr_warn("%s(): reset lookup entry badly specified, skipping\n",
175 list_add_tail(&entry->list, &reset_lookup_list);
177 mutex_unlock(&reset_lookup_mutex);
179 EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
181 static inline struct reset_control_array *
182 rstc_to_array(struct reset_control *rstc) {
183 return container_of(rstc, struct reset_control_array, base);
186 static int reset_control_array_reset(struct reset_control_array *resets)
190 for (i = 0; i < resets->num_rstcs; i++) {
191 ret = reset_control_reset(resets->rstc[i]);
199 static int reset_control_array_assert(struct reset_control_array *resets)
203 for (i = 0; i < resets->num_rstcs; i++) {
204 ret = reset_control_assert(resets->rstc[i]);
213 reset_control_deassert(resets->rstc[i]);
217 static int reset_control_array_deassert(struct reset_control_array *resets)
221 for (i = 0; i < resets->num_rstcs; i++) {
222 ret = reset_control_deassert(resets->rstc[i]);
231 reset_control_assert(resets->rstc[i]);
235 static inline bool reset_control_is_array(struct reset_control *rstc)
241 * reset_control_reset - reset the controlled device
242 * @rstc: reset controller
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
247 * Consumers must not use reset_control_(de)assert on shared reset lines when
248 * reset_control_reset has been used.
250 * If rstc is NULL it is an optional reset and the function will just
253 int reset_control_reset(struct reset_control *rstc)
260 if (WARN_ON(IS_ERR(rstc)))
263 if (reset_control_is_array(rstc))
264 return reset_control_array_reset(rstc_to_array(rstc));
266 if (!rstc->rcdev->ops->reset)
270 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
273 if (atomic_inc_return(&rstc->triggered_count) != 1)
277 ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
278 if (rstc->shared && ret)
279 atomic_dec(&rstc->triggered_count);
283 EXPORT_SYMBOL_GPL(reset_control_reset);
286 * reset_control_assert - asserts the reset line
287 * @rstc: reset controller
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.
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.
299 * If rstc is NULL it is an optional reset and the function will just
302 int reset_control_assert(struct reset_control *rstc)
307 if (WARN_ON(IS_ERR(rstc)))
310 if (reset_control_is_array(rstc))
311 return reset_control_array_assert(rstc_to_array(rstc));
314 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
317 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
320 if (atomic_dec_return(&rstc->deassert_count) != 0)
324 * Shared reset controls allow the reset line to be in any state
325 * after this call, so doing nothing is a valid option.
327 if (!rstc->rcdev->ops->assert)
331 * If the reset controller does not implement .assert(), there
332 * is no way to guarantee that the reset line is asserted after
335 if (!rstc->rcdev->ops->assert)
339 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
341 EXPORT_SYMBOL_GPL(reset_control_assert);
344 * reset_control_deassert - deasserts the reset line
345 * @rstc: reset controller
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.
352 * If rstc is NULL it is an optional reset and the function will just
355 int reset_control_deassert(struct reset_control *rstc)
360 if (WARN_ON(IS_ERR(rstc)))
363 if (reset_control_is_array(rstc))
364 return reset_control_array_deassert(rstc_to_array(rstc));
367 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
370 if (atomic_inc_return(&rstc->deassert_count) != 1)
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
381 if (!rstc->rcdev->ops->deassert)
384 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
386 EXPORT_SYMBOL_GPL(reset_control_deassert);
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
394 int reset_control_status(struct reset_control *rstc)
399 if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
402 if (rstc->rcdev->ops->status)
403 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
407 EXPORT_SYMBOL_GPL(reset_control_status);
409 static struct reset_control *__reset_control_get_internal(
410 struct reset_controller_dev *rcdev,
411 unsigned int index, bool shared)
413 struct reset_control *rstc;
415 lockdep_assert_held(&reset_list_mutex);
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);
422 kref_get(&rstc->refcnt);
427 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
429 return ERR_PTR(-ENOMEM);
431 try_module_get(rcdev->owner);
434 list_add(&rstc->list, &rcdev->reset_control_head);
436 kref_init(&rstc->refcnt);
437 rstc->shared = shared;
442 static void __reset_control_release(struct kref *kref)
444 struct reset_control *rstc = container_of(kref, struct reset_control,
447 lockdep_assert_held(&reset_list_mutex);
449 module_put(rstc->rcdev->owner);
451 list_del(&rstc->list);
455 static void __reset_control_put_internal(struct reset_control *rstc)
457 lockdep_assert_held(&reset_list_mutex);
459 kref_put(&rstc->refcnt, __reset_control_release);
462 struct reset_control *__of_reset_control_get(struct device_node *node,
463 const char *id, int index, bool shared,
466 struct reset_control *rstc;
467 struct reset_controller_dev *r, *rcdev;
468 struct of_phandle_args args;
473 return ERR_PTR(-EINVAL);
476 index = of_property_match_string(node,
478 if (index == -EILSEQ)
479 return ERR_PTR(index);
481 return optional ? NULL : ERR_PTR(-ENOENT);
484 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
489 return optional ? NULL : ERR_PTR(ret);
491 mutex_lock(&reset_list_mutex);
493 list_for_each_entry(r, &reset_controller_list, list) {
494 if (args.np == r->of_node) {
501 rstc = ERR_PTR(-EPROBE_DEFER);
505 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
506 rstc = ERR_PTR(-EINVAL);
510 rstc_id = rcdev->of_xlate(rcdev, &args);
512 rstc = ERR_PTR(rstc_id);
516 /* reset_list_mutex also protects the rcdev's reset_control list */
517 rstc = __reset_control_get_internal(rcdev, rstc_id, shared);
520 mutex_unlock(&reset_list_mutex);
521 of_node_put(args.np);
525 EXPORT_SYMBOL_GPL(__of_reset_control_get);
527 static struct reset_controller_dev *
528 __reset_controller_by_name(const char *name)
530 struct reset_controller_dev *rcdev;
532 lockdep_assert_held(&reset_list_mutex);
534 list_for_each_entry(rcdev, &reset_controller_list, list) {
538 if (!strcmp(name, dev_name(rcdev->dev)))
545 static struct reset_control *
546 __reset_control_get_from_lookup(struct device *dev, const char *con_id,
547 bool shared, bool optional)
549 const struct reset_control_lookup *lookup;
550 struct reset_controller_dev *rcdev;
551 const char *dev_id = dev_name(dev);
552 struct reset_control *rstc = NULL;
555 return ERR_PTR(-EINVAL);
557 mutex_lock(&reset_lookup_mutex);
559 list_for_each_entry(lookup, &reset_lookup_list, list) {
560 if (strcmp(lookup->dev_id, dev_id))
563 if ((!con_id && !lookup->con_id) ||
564 ((con_id && lookup->con_id) &&
565 !strcmp(con_id, lookup->con_id))) {
566 mutex_lock(&reset_list_mutex);
567 rcdev = __reset_controller_by_name(lookup->provider);
569 mutex_unlock(&reset_list_mutex);
570 mutex_unlock(&reset_lookup_mutex);
571 /* Reset provider may not be ready yet. */
572 return ERR_PTR(-EPROBE_DEFER);
575 rstc = __reset_control_get_internal(rcdev,
578 mutex_unlock(&reset_list_mutex);
583 mutex_unlock(&reset_lookup_mutex);
586 return optional ? NULL : ERR_PTR(-ENOENT);
591 struct reset_control *__reset_control_get(struct device *dev, const char *id,
592 int index, bool shared, bool optional)
595 return __of_reset_control_get(dev->of_node, id, index, shared,
598 return __reset_control_get_from_lookup(dev, id, shared, optional);
600 EXPORT_SYMBOL_GPL(__reset_control_get);
602 static void reset_control_array_put(struct reset_control_array *resets)
606 mutex_lock(&reset_list_mutex);
607 for (i = 0; i < resets->num_rstcs; i++)
608 __reset_control_put_internal(resets->rstc[i]);
609 mutex_unlock(&reset_list_mutex);
613 * reset_control_put - free the reset controller
614 * @rstc: reset controller
616 void reset_control_put(struct reset_control *rstc)
618 if (IS_ERR_OR_NULL(rstc))
621 if (reset_control_is_array(rstc)) {
622 reset_control_array_put(rstc_to_array(rstc));
626 mutex_lock(&reset_list_mutex);
627 __reset_control_put_internal(rstc);
628 mutex_unlock(&reset_list_mutex);
630 EXPORT_SYMBOL_GPL(reset_control_put);
632 static void devm_reset_control_release(struct device *dev, void *res)
634 reset_control_put(*(struct reset_control **)res);
637 struct reset_control *__devm_reset_control_get(struct device *dev,
638 const char *id, int index, bool shared,
641 struct reset_control **ptr, *rstc;
643 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
646 return ERR_PTR(-ENOMEM);
648 rstc = __reset_control_get(dev, id, index, shared, optional);
651 devres_add(dev, ptr);
658 EXPORT_SYMBOL_GPL(__devm_reset_control_get);
661 * device_reset - find reset controller associated with the device
663 * @dev: device to be reset by the controller
664 * @optional: whether it is optional to reset the device
666 * Convenience wrapper for __reset_control_get() and reset_control_reset().
667 * This is useful for the common case of devices with single, dedicated reset
670 int __device_reset(struct device *dev, bool optional)
672 struct reset_control *rstc;
675 rstc = __reset_control_get(dev, NULL, 0, 0, optional);
677 return PTR_ERR(rstc);
679 ret = reset_control_reset(rstc);
681 reset_control_put(rstc);
685 EXPORT_SYMBOL_GPL(__device_reset);
688 * APIs to manage an array of reset controls.
691 * of_reset_control_get_count - Count number of resets available with a device
693 * @node: device node that contains 'resets'.
695 * Returns positive reset count on success, or error number on failure and
696 * on count being zero.
698 static int of_reset_control_get_count(struct device_node *node)
705 count = of_count_phandle_with_args(node, "resets", "#reset-cells");
713 * of_reset_control_array_get - Get a list of reset controls using
716 * @np: device node for the device that requests the reset controls array
717 * @shared: whether reset controls are shared or not
718 * @optional: whether it is optional to get the reset controls
720 * Returns pointer to allocated reset_control_array on success or
723 struct reset_control *
724 of_reset_control_array_get(struct device_node *np, bool shared, bool optional)
726 struct reset_control_array *resets;
727 struct reset_control *rstc;
730 num = of_reset_control_get_count(np);
732 return optional ? NULL : ERR_PTR(num);
734 resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
736 return ERR_PTR(-ENOMEM);
738 for (i = 0; i < num; i++) {
739 rstc = __of_reset_control_get(np, NULL, i, shared, optional);
742 resets->rstc[i] = rstc;
744 resets->num_rstcs = num;
745 resets->base.array = true;
747 return &resets->base;
750 mutex_lock(&reset_list_mutex);
752 __reset_control_put_internal(resets->rstc[i]);
753 mutex_unlock(&reset_list_mutex);
759 EXPORT_SYMBOL_GPL(of_reset_control_array_get);
762 * devm_reset_control_array_get - Resource managed reset control array get
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
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.
772 * Returns pointer to allocated reset_control_array on success or
775 struct reset_control *
776 devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
778 struct reset_control **devres;
779 struct reset_control *rstc;
781 devres = devres_alloc(devm_reset_control_release, sizeof(*devres),
784 return ERR_PTR(-ENOMEM);
786 rstc = of_reset_control_array_get(dev->of_node, shared, optional);
793 devres_add(dev, devres);
797 EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
799 static int reset_control_get_count_from_lookup(struct device *dev)
801 const struct reset_control_lookup *lookup;
808 dev_id = dev_name(dev);
809 mutex_lock(&reset_lookup_mutex);
811 list_for_each_entry(lookup, &reset_lookup_list, list) {
812 if (!strcmp(lookup->dev_id, dev_id))
816 mutex_unlock(&reset_lookup_mutex);
825 * reset_control_get_count - Count number of resets available with a device
827 * @dev: device for which to return the number of resets
829 * Returns positive reset count on success, or error number on failure and
830 * on count being zero.
832 int reset_control_get_count(struct device *dev)
835 return of_reset_control_get_count(dev->of_node);
837 return reset_control_get_count_from_lookup(dev);
839 EXPORT_SYMBOL_GPL(reset_control_get_count);