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
79 * @flags: a flags pointer to fill in (optional)
81 * This simple translation function should be used for reset controllers
82 * with 1:1 mapping, where reset lines can be indexed by number without gaps.
84 static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
85 const struct of_phandle_args *reset_spec)
87 if (reset_spec->args[0] >= rcdev->nr_resets)
90 return reset_spec->args[0];
94 * reset_controller_register - register a reset controller device
95 * @rcdev: a pointer to the initialized reset controller device
97 int reset_controller_register(struct reset_controller_dev *rcdev)
99 if (!rcdev->of_xlate) {
100 rcdev->of_reset_n_cells = 1;
101 rcdev->of_xlate = of_reset_simple_xlate;
104 INIT_LIST_HEAD(&rcdev->reset_control_head);
106 mutex_lock(&reset_list_mutex);
107 list_add(&rcdev->list, &reset_controller_list);
108 mutex_unlock(&reset_list_mutex);
112 EXPORT_SYMBOL_GPL(reset_controller_register);
115 * reset_controller_unregister - unregister a reset controller device
116 * @rcdev: a pointer to the reset controller device
118 void reset_controller_unregister(struct reset_controller_dev *rcdev)
120 mutex_lock(&reset_list_mutex);
121 list_del(&rcdev->list);
122 mutex_unlock(&reset_list_mutex);
124 EXPORT_SYMBOL_GPL(reset_controller_unregister);
126 static void devm_reset_controller_release(struct device *dev, void *res)
128 reset_controller_unregister(*(struct reset_controller_dev **)res);
132 * devm_reset_controller_register - resource managed reset_controller_register()
133 * @dev: device that is registering this reset controller
134 * @rcdev: a pointer to the initialized reset controller device
136 * Managed reset_controller_register(). For reset controllers registered by
137 * this function, reset_controller_unregister() is automatically called on
138 * driver detach. See reset_controller_register() for more information.
140 int devm_reset_controller_register(struct device *dev,
141 struct reset_controller_dev *rcdev)
143 struct reset_controller_dev **rcdevp;
146 rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp),
151 ret = reset_controller_register(rcdev);
154 devres_add(dev, rcdevp);
161 EXPORT_SYMBOL_GPL(devm_reset_controller_register);
164 * reset_controller_add_lookup - register a set of lookup entries
165 * @lookup: array of reset lookup entries
166 * @num_entries: number of entries in the lookup array
168 void reset_controller_add_lookup(struct reset_control_lookup *lookup,
169 unsigned int num_entries)
171 struct reset_control_lookup *entry;
174 mutex_lock(&reset_lookup_mutex);
175 for (i = 0; i < num_entries; i++) {
178 if (!entry->dev_id || !entry->provider) {
179 pr_warn("%s(): reset lookup entry badly specified, skipping\n",
184 list_add_tail(&entry->list, &reset_lookup_list);
186 mutex_unlock(&reset_lookup_mutex);
188 EXPORT_SYMBOL_GPL(reset_controller_add_lookup);
190 static inline struct reset_control_array *
191 rstc_to_array(struct reset_control *rstc) {
192 return container_of(rstc, struct reset_control_array, base);
195 static int reset_control_array_reset(struct reset_control_array *resets)
199 for (i = 0; i < resets->num_rstcs; i++) {
200 ret = reset_control_reset(resets->rstc[i]);
208 static int reset_control_array_assert(struct reset_control_array *resets)
212 for (i = 0; i < resets->num_rstcs; i++) {
213 ret = reset_control_assert(resets->rstc[i]);
222 reset_control_deassert(resets->rstc[i]);
226 static int reset_control_array_deassert(struct reset_control_array *resets)
230 for (i = 0; i < resets->num_rstcs; i++) {
231 ret = reset_control_deassert(resets->rstc[i]);
240 reset_control_assert(resets->rstc[i]);
244 static int reset_control_array_acquire(struct reset_control_array *resets)
249 for (i = 0; i < resets->num_rstcs; i++) {
250 err = reset_control_acquire(resets->rstc[i]);
259 reset_control_release(resets->rstc[i]);
264 static void reset_control_array_release(struct reset_control_array *resets)
268 for (i = 0; i < resets->num_rstcs; i++)
269 reset_control_release(resets->rstc[i]);
272 static inline bool reset_control_is_array(struct reset_control *rstc)
278 * reset_control_reset - reset the controlled device
279 * @rstc: reset controller
281 * On a shared reset line the actual reset pulse is only triggered once for the
282 * lifetime of the reset_control instance: for all but the first caller this is
284 * Consumers must not use reset_control_(de)assert on shared reset lines when
285 * reset_control_reset has been used.
287 * If rstc is NULL it is an optional reset and the function will just
290 int reset_control_reset(struct reset_control *rstc)
297 if (WARN_ON(IS_ERR(rstc)))
300 if (reset_control_is_array(rstc))
301 return reset_control_array_reset(rstc_to_array(rstc));
303 if (!rstc->rcdev->ops->reset)
307 if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
310 if (atomic_inc_return(&rstc->triggered_count) != 1)
317 ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
318 if (rstc->shared && ret)
319 atomic_dec(&rstc->triggered_count);
323 EXPORT_SYMBOL_GPL(reset_control_reset);
326 * reset_control_assert - asserts the reset line
327 * @rstc: reset controller
329 * Calling this on an exclusive reset controller guarantees that the reset
330 * will be asserted. When called on a shared reset controller the line may
331 * still be deasserted, as long as other users keep it so.
333 * For shared reset controls a driver cannot expect the hw's registers and
334 * internal state to be reset, but must be prepared for this to happen.
335 * Consumers must not use reset_control_reset on shared reset lines when
336 * reset_control_(de)assert has been used.
339 * If rstc is NULL it is an optional reset and the function will just
342 int reset_control_assert(struct reset_control *rstc)
347 if (WARN_ON(IS_ERR(rstc)))
350 if (reset_control_is_array(rstc))
351 return reset_control_array_assert(rstc_to_array(rstc));
354 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
357 if (WARN_ON(atomic_read(&rstc->deassert_count) == 0))
360 if (atomic_dec_return(&rstc->deassert_count) != 0)
364 * Shared reset controls allow the reset line to be in any state
365 * after this call, so doing nothing is a valid option.
367 if (!rstc->rcdev->ops->assert)
371 * If the reset controller does not implement .assert(), there
372 * is no way to guarantee that the reset line is asserted after
375 if (!rstc->rcdev->ops->assert)
378 if (!rstc->acquired) {
379 WARN(1, "reset %s (ID: %u) is not acquired\n",
380 rcdev_name(rstc->rcdev), rstc->id);
385 return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
387 EXPORT_SYMBOL_GPL(reset_control_assert);
390 * reset_control_deassert - deasserts the reset line
391 * @rstc: reset controller
393 * After calling this function, the reset is guaranteed to be deasserted.
394 * Consumers must not use reset_control_reset on shared reset lines when
395 * reset_control_(de)assert has been used.
398 * If rstc is NULL it is an optional reset and the function will just
401 int reset_control_deassert(struct reset_control *rstc)
406 if (WARN_ON(IS_ERR(rstc)))
409 if (reset_control_is_array(rstc))
410 return reset_control_array_deassert(rstc_to_array(rstc));
413 if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))
416 if (atomic_inc_return(&rstc->deassert_count) != 1)
419 if (!rstc->acquired) {
420 WARN(1, "reset %s (ID: %u) is not acquired\n",
421 rcdev_name(rstc->rcdev), rstc->id);
427 * If the reset controller does not implement .deassert(), we assume
428 * that it handles self-deasserting reset lines via .reset(). In that
429 * case, the reset lines are deasserted by default. If that is not the
430 * case, the reset controller driver should implement .deassert() and
433 if (!rstc->rcdev->ops->deassert)
436 return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
438 EXPORT_SYMBOL_GPL(reset_control_deassert);
441 * reset_control_status - returns a negative errno if not supported, a
442 * positive value if the reset line is asserted, or zero if the reset
443 * line is not asserted or if the desc is NULL (optional reset).
444 * @rstc: reset controller
446 int reset_control_status(struct reset_control *rstc)
451 if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc))
454 if (rstc->rcdev->ops->status)
455 return rstc->rcdev->ops->status(rstc->rcdev, rstc->id);
459 EXPORT_SYMBOL_GPL(reset_control_status);
462 * reset_control_acquire() - acquires a reset control for exclusive use
463 * @rstc: reset control
465 * This is used to explicitly acquire a reset control for exclusive use. Note
466 * that exclusive resets are requested as acquired by default. In order for a
467 * second consumer to be able to control the reset, the first consumer has to
468 * release it first. Typically the easiest way to achieve this is to call the
469 * reset_control_get_exclusive_released() to obtain an instance of the reset
470 * control. Such reset controls are not acquired by default.
472 * Consumers implementing shared access to an exclusive reset need to follow
473 * a specific protocol in order to work together. Before consumers can change
474 * a reset they must acquire exclusive access using reset_control_acquire().
475 * After they are done operating the reset, they must release exclusive access
476 * with a call to reset_control_release(). Consumers are not granted exclusive
477 * access to the reset as long as another consumer hasn't released a reset.
479 * See also: reset_control_release()
481 int reset_control_acquire(struct reset_control *rstc)
483 struct reset_control *rc;
488 if (WARN_ON(IS_ERR(rstc)))
491 if (reset_control_is_array(rstc))
492 return reset_control_array_acquire(rstc_to_array(rstc));
494 mutex_lock(&reset_list_mutex);
496 if (rstc->acquired) {
497 mutex_unlock(&reset_list_mutex);
501 list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) {
502 if (rstc != rc && rstc->id == rc->id) {
504 mutex_unlock(&reset_list_mutex);
510 rstc->acquired = true;
512 mutex_unlock(&reset_list_mutex);
515 EXPORT_SYMBOL_GPL(reset_control_acquire);
518 * reset_control_release() - releases exclusive access to a reset control
519 * @rstc: reset control
521 * Releases exclusive access right to a reset control previously obtained by a
522 * call to reset_control_acquire(). Until a consumer calls this function, no
523 * other consumers will be granted exclusive access.
525 * See also: reset_control_acquire()
527 void reset_control_release(struct reset_control *rstc)
529 if (!rstc || WARN_ON(IS_ERR(rstc)))
532 if (reset_control_is_array(rstc))
533 reset_control_array_release(rstc_to_array(rstc));
535 rstc->acquired = false;
537 EXPORT_SYMBOL_GPL(reset_control_release);
539 static struct reset_control *__reset_control_get_internal(
540 struct reset_controller_dev *rcdev,
541 unsigned int index, bool shared, bool acquired)
543 struct reset_control *rstc;
545 lockdep_assert_held(&reset_list_mutex);
547 list_for_each_entry(rstc, &rcdev->reset_control_head, list) {
548 if (rstc->id == index) {
550 * Allow creating a secondary exclusive reset_control
551 * that is initially not acquired for an already
552 * controlled reset line.
554 if (!rstc->shared && !shared && !acquired)
557 if (WARN_ON(!rstc->shared || !shared))
558 return ERR_PTR(-EBUSY);
560 kref_get(&rstc->refcnt);
565 rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
567 return ERR_PTR(-ENOMEM);
569 try_module_get(rcdev->owner);
572 list_add(&rstc->list, &rcdev->reset_control_head);
574 kref_init(&rstc->refcnt);
575 rstc->acquired = acquired;
576 rstc->shared = shared;
581 static void __reset_control_release(struct kref *kref)
583 struct reset_control *rstc = container_of(kref, struct reset_control,
586 lockdep_assert_held(&reset_list_mutex);
588 module_put(rstc->rcdev->owner);
590 list_del(&rstc->list);
594 static void __reset_control_put_internal(struct reset_control *rstc)
596 lockdep_assert_held(&reset_list_mutex);
598 kref_put(&rstc->refcnt, __reset_control_release);
601 struct reset_control *__of_reset_control_get(struct device_node *node,
602 const char *id, int index, bool shared,
603 bool optional, bool acquired)
605 struct reset_control *rstc;
606 struct reset_controller_dev *r, *rcdev;
607 struct of_phandle_args args;
612 return ERR_PTR(-EINVAL);
615 index = of_property_match_string(node,
617 if (index == -EILSEQ)
618 return ERR_PTR(index);
620 return optional ? NULL : ERR_PTR(-ENOENT);
623 ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
628 return optional ? NULL : ERR_PTR(ret);
630 mutex_lock(&reset_list_mutex);
632 list_for_each_entry(r, &reset_controller_list, list) {
633 if (args.np == r->of_node) {
640 rstc = ERR_PTR(-EPROBE_DEFER);
644 if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
645 rstc = ERR_PTR(-EINVAL);
649 rstc_id = rcdev->of_xlate(rcdev, &args);
651 rstc = ERR_PTR(rstc_id);
655 /* reset_list_mutex also protects the rcdev's reset_control list */
656 rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
659 mutex_unlock(&reset_list_mutex);
660 of_node_put(args.np);
664 EXPORT_SYMBOL_GPL(__of_reset_control_get);
666 static struct reset_controller_dev *
667 __reset_controller_by_name(const char *name)
669 struct reset_controller_dev *rcdev;
671 lockdep_assert_held(&reset_list_mutex);
673 list_for_each_entry(rcdev, &reset_controller_list, list) {
677 if (!strcmp(name, dev_name(rcdev->dev)))
684 static struct reset_control *
685 __reset_control_get_from_lookup(struct device *dev, const char *con_id,
686 bool shared, bool optional, bool acquired)
688 const struct reset_control_lookup *lookup;
689 struct reset_controller_dev *rcdev;
690 const char *dev_id = dev_name(dev);
691 struct reset_control *rstc = NULL;
694 return ERR_PTR(-EINVAL);
696 mutex_lock(&reset_lookup_mutex);
698 list_for_each_entry(lookup, &reset_lookup_list, list) {
699 if (strcmp(lookup->dev_id, dev_id))
702 if ((!con_id && !lookup->con_id) ||
703 ((con_id && lookup->con_id) &&
704 !strcmp(con_id, lookup->con_id))) {
705 mutex_lock(&reset_list_mutex);
706 rcdev = __reset_controller_by_name(lookup->provider);
708 mutex_unlock(&reset_list_mutex);
709 mutex_unlock(&reset_lookup_mutex);
710 /* Reset provider may not be ready yet. */
711 return ERR_PTR(-EPROBE_DEFER);
714 rstc = __reset_control_get_internal(rcdev,
717 mutex_unlock(&reset_list_mutex);
722 mutex_unlock(&reset_lookup_mutex);
725 return optional ? NULL : ERR_PTR(-ENOENT);
730 struct reset_control *__reset_control_get(struct device *dev, const char *id,
731 int index, bool shared, bool optional,
734 if (WARN_ON(shared && acquired))
735 return ERR_PTR(-EINVAL);
738 return __of_reset_control_get(dev->of_node, id, index, shared,
741 return __reset_control_get_from_lookup(dev, id, shared, optional,
744 EXPORT_SYMBOL_GPL(__reset_control_get);
746 static void reset_control_array_put(struct reset_control_array *resets)
750 mutex_lock(&reset_list_mutex);
751 for (i = 0; i < resets->num_rstcs; i++)
752 __reset_control_put_internal(resets->rstc[i]);
753 mutex_unlock(&reset_list_mutex);
757 * reset_control_put - free the reset controller
758 * @rstc: reset controller
760 void reset_control_put(struct reset_control *rstc)
762 if (IS_ERR_OR_NULL(rstc))
765 if (reset_control_is_array(rstc)) {
766 reset_control_array_put(rstc_to_array(rstc));
770 mutex_lock(&reset_list_mutex);
771 __reset_control_put_internal(rstc);
772 mutex_unlock(&reset_list_mutex);
774 EXPORT_SYMBOL_GPL(reset_control_put);
776 static void devm_reset_control_release(struct device *dev, void *res)
778 reset_control_put(*(struct reset_control **)res);
781 struct reset_control *__devm_reset_control_get(struct device *dev,
782 const char *id, int index, bool shared,
783 bool optional, bool acquired)
785 struct reset_control **ptr, *rstc;
787 ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
790 return ERR_PTR(-ENOMEM);
792 rstc = __reset_control_get(dev, id, index, shared, optional, acquired);
795 devres_add(dev, ptr);
802 EXPORT_SYMBOL_GPL(__devm_reset_control_get);
805 * device_reset - find reset controller associated with the device
807 * @dev: device to be reset by the controller
808 * @optional: whether it is optional to reset the device
810 * Convenience wrapper for __reset_control_get() and reset_control_reset().
811 * This is useful for the common case of devices with single, dedicated reset
814 int __device_reset(struct device *dev, bool optional)
816 struct reset_control *rstc;
819 rstc = __reset_control_get(dev, NULL, 0, 0, optional, true);
821 return PTR_ERR(rstc);
823 ret = reset_control_reset(rstc);
825 reset_control_put(rstc);
829 EXPORT_SYMBOL_GPL(__device_reset);
832 * APIs to manage an array of reset controls.
835 * of_reset_control_get_count - Count number of resets available with a device
837 * @node: device node that contains 'resets'.
839 * Returns positive reset count on success, or error number on failure and
840 * on count being zero.
842 static int of_reset_control_get_count(struct device_node *node)
849 count = of_count_phandle_with_args(node, "resets", "#reset-cells");
857 * of_reset_control_array_get - Get a list of reset controls using
860 * @np: device node for the device that requests the reset controls array
861 * @shared: whether reset controls are shared or not
862 * @optional: whether it is optional to get the reset controls
863 * @acquired: only one reset control may be acquired for a given controller
866 * Returns pointer to allocated reset_control_array on success or
869 struct reset_control *
870 of_reset_control_array_get(struct device_node *np, bool shared, bool optional,
873 struct reset_control_array *resets;
874 struct reset_control *rstc;
877 num = of_reset_control_get_count(np);
879 return optional ? NULL : ERR_PTR(num);
881 resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL);
883 return ERR_PTR(-ENOMEM);
885 for (i = 0; i < num; i++) {
886 rstc = __of_reset_control_get(np, NULL, i, shared, optional,
890 resets->rstc[i] = rstc;
892 resets->num_rstcs = num;
893 resets->base.array = true;
895 return &resets->base;
898 mutex_lock(&reset_list_mutex);
900 __reset_control_put_internal(resets->rstc[i]);
901 mutex_unlock(&reset_list_mutex);
907 EXPORT_SYMBOL_GPL(of_reset_control_array_get);
910 * devm_reset_control_array_get - Resource managed reset control array get
912 * @dev: device that requests the list of reset controls
913 * @shared: whether reset controls are shared or not
914 * @optional: whether it is optional to get the reset controls
916 * The reset control array APIs are intended for a list of resets
917 * that just have to be asserted or deasserted, without any
918 * requirements on the order.
920 * Returns pointer to allocated reset_control_array on success or
923 struct reset_control *
924 devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
926 struct reset_control **devres;
927 struct reset_control *rstc;
929 devres = devres_alloc(devm_reset_control_release, sizeof(*devres),
932 return ERR_PTR(-ENOMEM);
934 rstc = of_reset_control_array_get(dev->of_node, shared, optional, true);
941 devres_add(dev, devres);
945 EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
947 static int reset_control_get_count_from_lookup(struct device *dev)
949 const struct reset_control_lookup *lookup;
956 dev_id = dev_name(dev);
957 mutex_lock(&reset_lookup_mutex);
959 list_for_each_entry(lookup, &reset_lookup_list, list) {
960 if (!strcmp(lookup->dev_id, dev_id))
964 mutex_unlock(&reset_lookup_mutex);
973 * reset_control_get_count - Count number of resets available with a device
975 * @dev: device for which to return the number of resets
977 * Returns positive reset count on success, or error number on failure and
978 * on count being zero.
980 int reset_control_get_count(struct device *dev)
983 return of_reset_control_get_count(dev->of_node);
985 return reset_control_get_count_from_lookup(dev);
987 EXPORT_SYMBOL_GPL(reset_control_get_count);