1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Reset Controller framework
5 * Copyright 2013 Philipp Zabel, Pengutronix
7 #include <linux/atomic.h>
8 #include <linux/device.h>
10 #include <linux/export.h>
11 #include <linux/kernel.h>
12 #include <linux/kref.h>
13 #include <linux/module.h>
15 #include <linux/reset.h>
16 #include <linux/reset-controller.h>
17 #include <linux/slab.h>
19 static DEFINE_MUTEX(reset_list_mutex);
20 static LIST_HEAD(reset_controller_list);
22 static DEFINE_MUTEX(reset_lookup_mutex);
23 static LIST_HEAD(reset_lookup_list);
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
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.
40 struct reset_control {
41 struct reset_controller_dev *rcdev;
42 struct list_head list;
48 atomic_t deassert_count;
49 atomic_t triggered_count;
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
58 struct reset_control_array {
59 struct reset_control base;
60 unsigned int num_rstcs;
61 struct reset_control *rstc[];
64 static const char *rcdev_name(struct reset_controller_dev *rcdev)
67 return dev_name(rcdev->dev);
70 return rcdev->of_node->full_name;
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
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.
83 static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
84 const struct of_phandle_args *reset_spec)
86 if (reset_spec->args[0] >= rcdev->nr_resets)
89 return reset_spec->args[0];
93 * reset_controller_register - register a reset controller device
94 * @rcdev: a pointer to the initialized reset controller device
96 int reset_controller_register(struct reset_controller_dev *rcdev)
98 if (!rcdev->of_xlate) {
99 rcdev->of_reset_n_cells = 1;
100 rcdev->of_xlate = of_reset_simple_xlate;
103 INIT_LIST_HEAD(&rcdev->reset_control_head);
105 mutex_lock(&reset_list_mutex);
106 list_add(&rcdev->list, &reset_controller_list);
107 mutex_unlock(&reset_list_mutex);
111 EXPORT_SYMBOL_GPL(reset_controller_register);
114 * reset_controller_unregister - unregister a reset controller device
115 * @rcdev: a pointer to the reset controller device
117 void reset_controller_unregister(struct reset_controller_dev *rcdev)
119 mutex_lock(&reset_list_mutex);
120 list_del(&rcdev->list);
121 mutex_unlock(&reset_list_mutex);
123 EXPORT_SYMBOL_GPL(reset_controller_unregister);
125 static void devm_reset_controller_release(struct device *dev, void *res)
127 reset_controller_unregister(*(struct reset_controller_dev **)res);
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
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.
139 int devm_reset_controller_register(struct device *dev,
140 struct reset_controller_dev *rcdev)
142 struct reset_controller_dev **rcdevp;
145 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
150 ret = reset_controller_register(rcdev);
153 devres_add(dev, rcdevp);
160 EXPORT_SYMBOL_GPL(devm_reset_controller_register);
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
167 void reset_controller_add_lookup(struct reset_control_lookup *lookup,
168 unsigned int num_entries)
170 struct reset_control_lookup *entry;
173 mutex_lock(&reset_lookup_mutex);
174 for (i = 0; i < num_entries; i++) {
177 if (!entry->dev_id || !entry->provider) {
178 pr_warn("%s(): reset lookup entry badly specified, skipping\n",
183 list_add_tail(&entry->list, &reset_lookup_list);
185 mutex_unlock(&reset_lookup_mutex);
187 EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
189 static inline struct reset_control_array *
190 rstc_to_array(struct reset_control *rstc) {
191 return container_of(rstc, struct reset_control_array, base);
194 static int reset_control_array_reset(struct reset_control_array *resets)
198 for (i = 0; i < resets->num_rstcs; i++) {
199 ret = reset_control_reset(resets->rstc[i]);
207 static int reset_control_array_assert(struct reset_control_array *resets)
211 for (i = 0; i < resets->num_rstcs; i++) {
212 ret = reset_control_assert(resets->rstc[i]);
221 reset_control_deassert(resets->rstc[i]);
225 static int reset_control_array_deassert(struct reset_control_array *resets)
229 for (i = 0; i < resets->num_rstcs; i++) {
230 ret = reset_control_deassert(resets->rstc[i]);
239 reset_control_assert(resets->rstc[i]);
243 static int reset_control_array_acquire(struct reset_control_array *resets)
248 for (i = 0; i < resets->num_rstcs; i++) {
249 err = reset_control_acquire(resets->rstc[i]);
258 reset_control_release(resets->rstc[i]);
263 static void reset_control_array_release(struct reset_control_array *resets)
267 for (i = 0; i < resets->num_rstcs; i++)
268 reset_control_release(resets->rstc[i]);
271 static inline bool reset_control_is_array(struct reset_control *rstc)
277 * reset_control_reset - reset the controlled device
278 * @rstc: reset controller
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
283 * Consumers must not use reset_control_(de)assert on shared reset lines when
284 * reset_control_reset has been used.
286 * If rstc is NULL it is an optional reset and the function will just
289 int reset_control_reset(struct reset_control *rstc)
296 if (WARN_ON(IS_ERR(rstc)))
299 if (reset_control_is_array(rstc))
300 return reset_control_array_reset(rstc_to_array(rstc));
302 if (!rstc->rcdev->ops->reset)
306 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
309 if (atomic_inc_return(&rstc->triggered_count) != 1)
316 ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
317 if (rstc->shared && ret)
318 atomic_dec(&rstc->triggered_count);
322 EXPORT_SYMBOL_GPL(reset_control_reset);
325 * reset_control_assert - asserts the reset line
326 * @rstc: reset controller
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.
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.
338 * If rstc is NULL it is an optional reset and the function will just
341 int reset_control_assert(struct reset_control *rstc)
346 if (WARN_ON(IS_ERR(rstc)))
349 if (reset_control_is_array(rstc))
350 return reset_control_array_assert(rstc_to_array(rstc));
353 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
356 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
359 if (atomic_dec_return(&rstc->deassert_count) != 0)
363 * Shared reset controls allow the reset line to be in any state
364 * after this call, so doing nothing is a valid option.
366 if (!rstc->rcdev->ops->assert)
370 * If the reset controller does not implement .assert(), there
371 * is no way to guarantee that the reset line is asserted after
374 if (!rstc->rcdev->ops->assert)
377 if (!rstc->acquired) {
378 WARN(1, "reset %s (ID: %u) is not acquired\n",
379 rcdev_name(rstc->rcdev), rstc->id);
384 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
386 EXPORT_SYMBOL_GPL(reset_control_assert);
389 * reset_control_deassert - deasserts the reset line
390 * @rstc: reset controller
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.
397 * If rstc is NULL it is an optional reset and the function will just
400 int reset_control_deassert(struct reset_control *rstc)
405 if (WARN_ON(IS_ERR(rstc)))
408 if (reset_control_is_array(rstc))
409 return reset_control_array_deassert(rstc_to_array(rstc));
412 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
415 if (atomic_inc_return(&rstc->deassert_count) != 1)
418 if (!rstc->acquired) {
419 WARN(1, "reset %s (ID: %u) is not acquired\n",
420 rcdev_name(rstc->rcdev), rstc->id);
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
432 if (!rstc->rcdev->ops->deassert)
435 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
437 EXPORT_SYMBOL_GPL(reset_control_deassert);
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
445 int reset_control_status(struct reset_control *rstc)
450 if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
453 if (rstc->rcdev->ops->status)
454 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
458 EXPORT_SYMBOL_GPL(reset_control_status);
461 * reset_control_acquire() - acquires a reset control for exclusive use
462 * @rstc: reset control
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.
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.
478 * See also: reset_control_release()
480 int reset_control_acquire(struct reset_control *rstc)
482 struct reset_control *rc;
487 if (WARN_ON(IS_ERR(rstc)))
490 if (reset_control_is_array(rstc))
491 return reset_control_array_acquire(rstc_to_array(rstc));
493 mutex_lock(&reset_list_mutex);
495 if (rstc->acquired) {
496 mutex_unlock(&reset_list_mutex);
500 list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
501 if (rstc != rc && rstc->id == rc->id) {
503 mutex_unlock(&reset_list_mutex);
509 rstc->acquired = true;
511 mutex_unlock(&reset_list_mutex);
514 EXPORT_SYMBOL_GPL(reset_control_acquire);
517 * reset_control_release() - releases exclusive access to a reset control
518 * @rstc: reset control
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.
524 * See also: reset_control_acquire()
526 void reset_control_release(struct reset_control *rstc)
528 if (!rstc || WARN_ON(IS_ERR(rstc)))
531 if (reset_control_is_array(rstc))
532 reset_control_array_release(rstc_to_array(rstc));
534 rstc->acquired = false;
536 EXPORT_SYMBOL_GPL(reset_control_release);
538 static struct reset_control *__reset_control_get_internal(
539 struct reset_controller_dev *rcdev,
540 unsigned int index, bool shared, bool acquired)
542 struct reset_control *rstc;
544 lockdep_assert_held(&reset_list_mutex);
546 list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
547 if (rstc->id == index) {
549 * Allow creating a secondary exclusive reset_control
550 * that is initially not acquired for an already
551 * controlled reset line.
553 if (!rstc->shared && !shared && !acquired)
556 if (WARN_ON(!rstc->shared || !shared))
557 return ERR_PTR(-EBUSY);
559 kref_get(&rstc->refcnt);
564 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
566 return ERR_PTR(-ENOMEM);
568 try_module_get(rcdev->owner);
571 list_add(&rstc->list, &rcdev->reset_control_head);
573 kref_init(&rstc->refcnt);
574 rstc->acquired = acquired;
575 rstc->shared = shared;
580 static void __reset_control_release(struct kref *kref)
582 struct reset_control *rstc = container_of(kref, struct reset_control,
585 lockdep_assert_held(&reset_list_mutex);
587 module_put(rstc->rcdev->owner);
589 list_del(&rstc->list);
593 static void __reset_control_put_internal(struct reset_control *rstc)
595 lockdep_assert_held(&reset_list_mutex);
597 kref_put(&rstc->refcnt, __reset_control_release);
600 struct reset_control *__of_reset_control_get(struct device_node *node,
601 const char *id, int index, bool shared,
602 bool optional, bool acquired)
604 struct reset_control *rstc;
605 struct reset_controller_dev *r, *rcdev;
606 struct of_phandle_args args;
611 return ERR_PTR(-EINVAL);
614 index = of_property_match_string(node,
616 if (index == -EILSEQ)
617 return ERR_PTR(index);
619 return optional ? NULL : ERR_PTR(-ENOENT);
622 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
627 return optional ? NULL : ERR_PTR(ret);
629 mutex_lock(&reset_list_mutex);
631 list_for_each_entry(r, &reset_controller_list, list) {
632 if (args.np == r->of_node) {
639 rstc = ERR_PTR(-EPROBE_DEFER);
643 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
644 rstc = ERR_PTR(-EINVAL);
648 rstc_id = rcdev->of_xlate(rcdev, &args);
650 rstc = ERR_PTR(rstc_id);
654 /* reset_list_mutex also protects the rcdev's reset_control list */
655 rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
658 mutex_unlock(&reset_list_mutex);
659 of_node_put(args.np);
663 EXPORT_SYMBOL_GPL(__of_reset_control_get);
665 static struct reset_controller_dev *
666 __reset_controller_by_name(const char *name)
668 struct reset_controller_dev *rcdev;
670 lockdep_assert_held(&reset_list_mutex);
672 list_for_each_entry(rcdev, &reset_controller_list, list) {
676 if (!strcmp(name, dev_name(rcdev->dev)))
683 static struct reset_control *
684 __reset_control_get_from_lookup(struct device *dev, const char *con_id,
685 bool shared, bool optional, bool acquired)
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;
692 mutex_lock(&reset_lookup_mutex);
694 list_for_each_entry(lookup, &reset_lookup_list, list) {
695 if (strcmp(lookup->dev_id, dev_id))
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);
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);
710 rstc = __reset_control_get_internal(rcdev,
713 mutex_unlock(&reset_list_mutex);
718 mutex_unlock(&reset_lookup_mutex);
721 return optional ? NULL : ERR_PTR(-ENOENT);
726 struct reset_control *__reset_control_get(struct device *dev, const char *id,
727 int index, bool shared, bool optional,
730 if (WARN_ON(shared && acquired))
731 return ERR_PTR(-EINVAL);
734 return __of_reset_control_get(dev->of_node, id, index, shared,
737 return __reset_control_get_from_lookup(dev, id, shared, optional,
740 EXPORT_SYMBOL_GPL(__reset_control_get);
742 static void reset_control_array_put(struct reset_control_array *resets)
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);
754 * reset_control_put - free the reset controller
755 * @rstc: reset controller
757 void reset_control_put(struct reset_control *rstc)
759 if (IS_ERR_OR_NULL(rstc))
762 if (reset_control_is_array(rstc)) {
763 reset_control_array_put(rstc_to_array(rstc));
767 mutex_lock(&reset_list_mutex);
768 __reset_control_put_internal(rstc);
769 mutex_unlock(&reset_list_mutex);
771 EXPORT_SYMBOL_GPL(reset_control_put);
773 static void devm_reset_control_release(struct device *dev, void *res)
775 reset_control_put(*(struct reset_control **)res);
778 struct reset_control *__devm_reset_control_get(struct device *dev,
779 const char *id, int index, bool shared,
780 bool optional, bool acquired)
782 struct reset_control **ptr, *rstc;
784 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
787 return ERR_PTR(-ENOMEM);
789 rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
792 devres_add(dev, ptr);
799 EXPORT_SYMBOL_GPL(__devm_reset_control_get);
802 * device_reset - find reset controller associated with the device
804 * @dev: device to be reset by the controller
805 * @optional: whether it is optional to reset the device
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
811 int __device_reset(struct device *dev, bool optional)
813 struct reset_control *rstc;
816 rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
818 return PTR_ERR(rstc);
820 ret = reset_control_reset(rstc);
822 reset_control_put(rstc);
826 EXPORT_SYMBOL_GPL(__device_reset);
829 * APIs to manage an array of reset controls.
833 * of_reset_control_get_count - Count number of resets available with a device
835 * @node: device node that contains 'resets'.
837 * Returns positive reset count on success, or error number on failure and
838 * on count being zero.
840 static int of_reset_control_get_count(struct device_node *node)
847 count = of_count_phandle_with_args(node, "resets", "#reset-cells");
855 * of_reset_control_array_get - Get a list of reset controls using
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
864 * Returns pointer to allocated reset_control_array on success or
867 struct reset_control *
868 of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
871 struct reset_control_array *resets;
872 struct reset_control *rstc;
875 num = of_reset_control_get_count(np);
877 return optional ? NULL : ERR_PTR(num);
879 resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
881 return ERR_PTR(-ENOMEM);
883 for (i = 0; i < num; i++) {
884 rstc = __of_reset_control_get(np, NULL, i, shared, optional,
888 resets->rstc[i] = rstc;
890 resets->num_rstcs = num;
891 resets->base.array = true;
893 return &resets->base;
896 mutex_lock(&reset_list_mutex);
898 __reset_control_put_internal(resets->rstc[i]);
899 mutex_unlock(&reset_list_mutex);
905 EXPORT_SYMBOL_GPL(of_reset_control_array_get);
908 * devm_reset_control_array_get - Resource managed reset control array get
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
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.
918 * Returns pointer to allocated reset_control_array on success or
921 struct reset_control *
922 devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
924 struct reset_control **devres;
925 struct reset_control *rstc;
927 devres = devres_alloc(devm_reset_control_release, sizeof(*devres),
930 return ERR_PTR(-ENOMEM);
932 rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
939 devres_add(dev, devres);
943 EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
945 static int reset_control_get_count_from_lookup(struct device *dev)
947 const struct reset_control_lookup *lookup;
954 dev_id = dev_name(dev);
955 mutex_lock(&reset_lookup_mutex);
957 list_for_each_entry(lookup, &reset_lookup_list, list) {
958 if (!strcmp(lookup->dev_id, dev_id))
962 mutex_unlock(&reset_lookup_mutex);
971 * reset_control_get_count - Count number of resets available with a device
973 * @dev: device for which to return the number of resets
975 * Returns positive reset count on success, or error number on failure and
976 * on count being zero.
978 int reset_control_get_count(struct device *dev)
981 return of_reset_control_get_count(dev->of_node);
983 return reset_control_get_count_from_lookup(dev);
985 EXPORT_SYMBOL_GPL(reset_control_get_count);