// SPDX-License-Identifier: GPL-2.0-or-later /* * Reset Controller framework * * Copyright 2013 Philipp Zabel, Pengutronix */ #include <linux/atomic.h> #include <linux/device.h> #include <linux/err.h> #include <linux/export.h> #include <linux/kernel.h> #include <linux/kref.h> #include <linux/module.h> #include <linux/of.h> #include <linux/reset.h> #include <linux/reset-controller.h> #include <linux/slab.h> static DEFINE_MUTEX(reset_list_mutex); static LIST_HEAD(reset_controller_list); static DEFINE_MUTEX(reset_lookup_mutex); static LIST_HEAD(reset_lookup_list); /** * struct reset_control - a reset control * @rcdev: a pointer to the reset controller device * this reset control belongs to * @list: list entry for the rcdev's reset controller list * @id: ID of the reset controller in the reset * controller device * @refcnt: Number of gets of this reset_control * @acquired: Only one reset_control may be acquired for a given rcdev and id. * @shared: Is this a shared (1), or an exclusive (0) reset_control? * @deassert_cnt: Number of times this reset line has been deasserted * @triggered_count: Number of times this reset line has been reset. Currently * only used for shared resets, which means that the value * will be either 0 or 1. */ struct reset_control { struct reset_controller_dev *rcdev; struct list_head list; unsigned int id; struct kref refcnt; bool acquired; bool shared; bool array; atomic_t deassert_count; atomic_t triggered_count; }; /** * struct reset_control_array - an array of reset controls * @base: reset control for compatibility with reset control API functions * @num_rstcs: number of reset controls * @rstc: array of reset controls */ struct reset_control_array { struct reset_control base; unsigned int num_rstcs; struct reset_control *rstc[]; }; static const char *rcdev_name(struct reset_controller_dev *rcdev) { if (rcdev->dev) return dev_name(rcdev->dev); if (rcdev->of_node) return rcdev->of_node->full_name; return NULL; } /** * of_reset_simple_xlate - translate reset_spec to the reset line number * @rcdev: a pointer to the reset controller device * @reset_spec: reset line specifier as found in the device tree * @flags: a flags pointer to fill in (optional) * * This simple translation function should be used for reset controllers * with 1:1 mapping, where reset lines can be indexed by number without gaps. */ static int of_reset_simple_xlate(struct reset_controller_dev *rcdev, const struct of_phandle_args *reset_spec) { if (reset_spec->args[0] >= rcdev->nr_resets) return -EINVAL; return reset_spec->args[0]; } /** * reset_controller_register - register a reset controller device * @rcdev: a pointer to the initialized reset controller device */ int reset_controller_register(struct reset_controller_dev *rcdev) { if (!rcdev->of_xlate) { rcdev->of_reset_n_cells = 1; rcdev->of_xlate = of_reset_simple_xlate; } INIT_LIST_HEAD(&rcdev->reset_control_head); mutex_lock(&reset_list_mutex); list_add(&rcdev->list, &reset_controller_list); mutex_unlock(&reset_list_mutex); return 0; } EXPORT_SYMBOL_GPL(reset_controller_register); /** * reset_controller_unregister - unregister a reset controller device * @rcdev: a pointer to the reset controller device */ void reset_controller_unregister(struct reset_controller_dev *rcdev) { mutex_lock(&reset_list_mutex); list_del(&rcdev->list); mutex_unlock(&reset_list_mutex); } EXPORT_SYMBOL_GPL(reset_controller_unregister); static void devm_reset_controller_release(struct device *dev, void *res) { reset_controller_unregister(*(struct reset_controller_dev **)res); } /** * devm_reset_controller_register - resource managed reset_controller_register() * @dev: device that is registering this reset controller * @rcdev: a pointer to the initialized reset controller device * * Managed reset_controller_register(). For reset controllers registered by * this function, reset_controller_unregister() is automatically called on * driver detach. See reset_controller_register() for more information. */ int devm_reset_controller_register(struct device *dev, struct reset_controller_dev *rcdev) { struct reset_controller_dev **rcdevp; int ret; rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp), GFP_KERNEL); if (!rcdevp) return -ENOMEM; ret = reset_controller_register(rcdev); if (!ret) { *rcdevp = rcdev; devres_add(dev, rcdevp); } else { devres_free(rcdevp); } return ret; } EXPORT_SYMBOL_GPL(devm_reset_controller_register); /** * reset_controller_add_lookup - register a set of lookup entries * @lookup: array of reset lookup entries * @num_entries: number of entries in the lookup array */ void reset_controller_add_lookup(struct reset_control_lookup *lookup, unsigned int num_entries) { struct reset_control_lookup *entry; unsigned int i; mutex_lock(&reset_lookup_mutex); for (i = 0; i < num_entries; i++) { entry = &lookup[i]; if (!entry->dev_id || !entry->provider) { pr_warn("%s(): reset lookup entry badly specified, skipping\n", __func__); continue; } list_add_tail(&entry->list, &reset_lookup_list); } mutex_unlock(&reset_lookup_mutex); } EXPORT_SYMBOL_GPL(reset_controller_add_lookup); static inline struct reset_control_array * rstc_to_array(struct reset_control *rstc) { return container_of(rstc, struct reset_control_array, base); } static int reset_control_array_reset(struct reset_control_array *resets) { int ret, i; for (i = 0; i < resets->num_rstcs; i++) { ret = reset_control_reset(resets->rstc[i]); if (ret) return ret; } return 0; } static int reset_control_array_assert(struct reset_control_array *resets) { int ret, i; for (i = 0; i < resets->num_rstcs; i++) { ret = reset_control_assert(resets->rstc[i]); if (ret) goto err; } return 0; err: while (i--) reset_control_deassert(resets->rstc[i]); return ret; } static int reset_control_array_deassert(struct reset_control_array *resets) { int ret, i; for (i = 0; i < resets->num_rstcs; i++) { ret = reset_control_deassert(resets->rstc[i]); if (ret) goto err; } return 0; err: while (i--) reset_control_assert(resets->rstc[i]); return ret; } static int reset_control_array_acquire(struct reset_control_array *resets) { unsigned int i; int err; for (i = 0; i < resets->num_rstcs; i++) { err = reset_control_acquire(resets->rstc[i]); if (err < 0) goto release; } return 0; release: while (i--) reset_control_release(resets->rstc[i]); return err; } static void reset_control_array_release(struct reset_control_array *resets) { unsigned int i; for (i = 0; i < resets->num_rstcs; i++) reset_control_release(resets->rstc[i]); } static inline bool reset_control_is_array(struct reset_control *rstc) { return rstc->array; } /** * reset_control_reset - reset the controlled device * @rstc: reset controller * * On a shared reset line the actual reset pulse is only triggered once for the * lifetime of the reset_control instance: for all but the first caller this is * a no-op. * Consumers must not use reset_control_(de)assert on shared reset lines when * reset_control_reset has been used. * * If rstc is NULL it is an optional reset and the function will just * return 0. */ int reset_control_reset(struct reset_control *rstc) { int ret; if (!rstc) return 0; if (WARN_ON(IS_ERR(rstc))) return -EINVAL; if (reset_control_is_array(rstc)) return reset_control_array_reset(rstc_to_array(rstc)); if (!rstc->rcdev->ops->reset) return -ENOTSUPP; if (rstc->shared) { if (WARN_ON(atomic_read(&rstc->deassert_count) != 0)) return -EINVAL; if (atomic_inc_return(&rstc->triggered_count) != 1) return 0; } else { if (!rstc->acquired) return -EPERM; } ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); if (rstc->shared && ret) atomic_dec(&rstc->triggered_count); return ret; } EXPORT_SYMBOL_GPL(reset_control_reset); /** * reset_control_assert - asserts the reset line * @rstc: reset controller * * Calling this on an exclusive reset controller guarantees that the reset * will be asserted. When called on a shared reset controller the line may * still be deasserted, as long as other users keep it so. * * For shared reset controls a driver cannot expect the hw's registers and * internal state to be reset, but must be prepared for this to happen. * Consumers must not use reset_control_reset on shared reset lines when * reset_control_(de)assert has been used. * return 0. * * If rstc is NULL it is an optional reset and the function will just * return 0. */ int reset_control_assert(struct reset_control *rstc) { if (!rstc) return 0; if (WARN_ON(IS_ERR(rstc))) return -EINVAL; if (reset_control_is_array(rstc)) return reset_control_array_assert(rstc_to_array(rstc)); if (rstc->shared) { if (WARN_ON(atomic_read(&rstc->triggered_count) != 0)) return -EINVAL; if (WARN_ON(atomic_read(&rstc->deassert_count) == 0)) return -EINVAL; if (atomic_dec_return(&rstc->deassert_count) != 0) return 0; /* * Shared reset controls allow the reset line to be in any state * after this call, so doing nothing is a valid option. */ if (!rstc->rcdev->ops->assert) return 0; } else { /* * If the reset controller does not implement .assert(), there * is no way to guarantee that the reset line is asserted after * this call. */ if (!rstc->rcdev->ops->assert) return -ENOTSUPP; if (!rstc->acquired) { WARN(1, "reset %s (ID: %u) is not acquired\n", rcdev_name(rstc->rcdev), rstc->id); return -EPERM; } } return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_assert); /** * reset_control_deassert - deasserts the reset line * @rstc: reset controller * * After calling this function, the reset is guaranteed to be deasserted. * Consumers must not use reset_control_reset on shared reset lines when * reset_control_(de)assert has been used. * return 0. * * If rstc is NULL it is an optional reset and the function will just * return 0. */ int reset_control_deassert(struct reset_control *rstc) { if (!rstc) return 0; if (WARN_ON(IS_ERR(rstc))) return -EINVAL; if (reset_control_is_array(rstc)) return reset_control_array_deassert(rstc_to_array(rstc)); if (rstc->shared) { if (WARN_ON(atomic_read(&rstc->triggered_count) != 0)) return -EINVAL; if (atomic_inc_return(&rstc->deassert_count) != 1) return 0; } else { if (!rstc->acquired) { WARN(1, "reset %s (ID: %u) is not acquired\n", rcdev_name(rstc->rcdev), rstc->id); return -EPERM; } } /* * If the reset controller does not implement .deassert(), we assume * that it handles self-deasserting reset lines via .reset(). In that * case, the reset lines are deasserted by default. If that is not the * case, the reset controller driver should implement .deassert() and * return -ENOTSUPP. */ if (!rstc->rcdev->ops->deassert) return 0; return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_deassert); /** * reset_control_status - returns a negative errno if not supported, a * positive value if the reset line is asserted, or zero if the reset * line is not asserted or if the desc is NULL (optional reset). * @rstc: reset controller */ int reset_control_status(struct reset_control *rstc) { if (!rstc) return 0; if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc)) return -EINVAL; if (rstc->rcdev->ops->status) return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); return -ENOTSUPP; } EXPORT_SYMBOL_GPL(reset_control_status); /** * reset_control_acquire() - acquires a reset control for exclusive use * @rstc: reset control * * This is used to explicitly acquire a reset control for exclusive use. Note * that exclusive resets are requested as acquired by default. In order for a * second consumer to be able to control the reset, the first consumer has to * release it first. Typically the easiest way to achieve this is to call the * reset_control_get_exclusive_released() to obtain an instance of the reset * control. Such reset controls are not acquired by default. * * Consumers implementing shared access to an exclusive reset need to follow * a specific protocol in order to work together. Before consumers can change * a reset they must acquire exclusive access using reset_control_acquire(). * After they are done operating the reset, they must release exclusive access * with a call to reset_control_release(). Consumers are not granted exclusive * access to the reset as long as another consumer hasn't released a reset. * * See also: reset_control_release() */ int reset_control_acquire(struct reset_control *rstc) { struct reset_control *rc; if (!rstc) return 0; if (WARN_ON(IS_ERR(rstc))) return -EINVAL; if (reset_control_is_array(rstc)) return reset_control_array_acquire(rstc_to_array(rstc)); mutex_lock(&reset_list_mutex); if (rstc->acquired) { mutex_unlock(&reset_list_mutex); return 0; } list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) { if (rstc != rc && rstc->id == rc->id) { if (rc->acquired) { mutex_unlock(&reset_list_mutex); return -EBUSY; } } } rstc->acquired = true; mutex_unlock(&reset_list_mutex); return 0; } EXPORT_SYMBOL_GPL(reset_control_acquire); /** * reset_control_release() - releases exclusive access to a reset control * @rstc: reset control * * Releases exclusive access right to a reset control previously obtained by a * call to reset_control_acquire(). Until a consumer calls this function, no * other consumers will be granted exclusive access. * * See also: reset_control_acquire() */ void reset_control_release(struct reset_control *rstc) { if (!rstc || WARN_ON(IS_ERR(rstc))) return; if (reset_control_is_array(rstc)) reset_control_array_release(rstc_to_array(rstc)); else rstc->acquired = false; } EXPORT_SYMBOL_GPL(reset_control_release); static struct reset_control *__reset_control_get_internal( struct reset_controller_dev *rcdev, unsigned int index, bool shared, bool acquired) { struct reset_control *rstc; lockdep_assert_held(&reset_list_mutex); list_for_each_entry(rstc, &rcdev->reset_control_head, list) { if (rstc->id == index) { /* * Allow creating a secondary exclusive reset_control * that is initially not acquired for an already * controlled reset line. */ if (!rstc->shared && !shared && !acquired) break; if (WARN_ON(!rstc->shared || !shared)) return ERR_PTR(-EBUSY); kref_get(&rstc->refcnt); return rstc; } } rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); if (!rstc) return ERR_PTR(-ENOMEM); try_module_get(rcdev->owner); rstc->rcdev = rcdev; list_add(&rstc->list, &rcdev->reset_control_head); rstc->id = index; kref_init(&rstc->refcnt); rstc->acquired = acquired; rstc->shared = shared; return rstc; } static void __reset_control_release(struct kref *kref) { struct reset_control *rstc = container_of(kref, struct reset_control, refcnt); lockdep_assert_held(&reset_list_mutex); module_put(rstc->rcdev->owner); list_del(&rstc->list); kfree(rstc); } static void __reset_control_put_internal(struct reset_control *rstc) { lockdep_assert_held(&reset_list_mutex); kref_put(&rstc->refcnt, __reset_control_release); } struct reset_control *__of_reset_control_get(struct device_node *node, const char *id, int index, bool shared, bool optional, bool acquired) { struct reset_control *rstc; struct reset_controller_dev *r, *rcdev; struct of_phandle_args args; int rstc_id; int ret; if (!node) return ERR_PTR(-EINVAL); if (id) { index = of_property_match_string(node, "reset-names", id); if (index == -EILSEQ) return ERR_PTR(index); if (index < 0) return optional ? NULL : ERR_PTR(-ENOENT); } ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", index, &args); if (ret == -EINVAL) return ERR_PTR(ret); if (ret) return optional ? NULL : ERR_PTR(ret); mutex_lock(&reset_list_mutex); rcdev = NULL; list_for_each_entry(r, &reset_controller_list, list) { if (args.np == r->of_node) { rcdev = r; break; } } if (!rcdev) { rstc = ERR_PTR(-EPROBE_DEFER); goto out; } if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) { rstc = ERR_PTR(-EINVAL); goto out; } rstc_id = rcdev->of_xlate(rcdev, &args); if (rstc_id < 0) { rstc = ERR_PTR(rstc_id); goto out; } /* reset_list_mutex also protects the rcdev's reset_control list */ rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired); out: mutex_unlock(&reset_list_mutex); of_node_put(args.np); return rstc; } EXPORT_SYMBOL_GPL(__of_reset_control_get); static struct reset_controller_dev * __reset_controller_by_name(const char *name) { struct reset_controller_dev *rcdev; lockdep_assert_held(&reset_list_mutex); list_for_each_entry(rcdev, &reset_controller_list, list) { if (!rcdev->dev) continue; if (!strcmp(name, dev_name(rcdev->dev))) return rcdev; } return NULL; } static struct reset_control * __reset_control_get_from_lookup(struct device *dev, const char *con_id, bool shared, bool optional, bool acquired) { const struct reset_control_lookup *lookup; struct reset_controller_dev *rcdev; const char *dev_id = dev_name(dev); struct reset_control *rstc = NULL; if (!dev) return ERR_PTR(-EINVAL); mutex_lock(&reset_lookup_mutex); list_for_each_entry(lookup, &reset_lookup_list, list) { if (strcmp(lookup->dev_id, dev_id)) continue; if ((!con_id && !lookup->con_id) || ((con_id && lookup->con_id) && !strcmp(con_id, lookup->con_id))) { mutex_lock(&reset_list_mutex); rcdev = __reset_controller_by_name(lookup->provider); if (!rcdev) { mutex_unlock(&reset_list_mutex); mutex_unlock(&reset_lookup_mutex); /* Reset provider may not be ready yet. */ return ERR_PTR(-EPROBE_DEFER); } rstc = __reset_control_get_internal(rcdev, lookup->index, shared, acquired); mutex_unlock(&reset_list_mutex); break; } } mutex_unlock(&reset_lookup_mutex); if (!rstc) return optional ? NULL : ERR_PTR(-ENOENT); return rstc; } struct reset_control *__reset_control_get(struct device *dev, const char *id, int index, bool shared, bool optional, bool acquired) { if (WARN_ON(shared && acquired)) return ERR_PTR(-EINVAL); if (dev->of_node) return __of_reset_control_get(dev->of_node, id, index, shared, optional, acquired); return __reset_control_get_from_lookup(dev, id, shared, optional, acquired); } EXPORT_SYMBOL_GPL(__reset_control_get); static void reset_control_array_put(struct reset_control_array *resets) { int i; mutex_lock(&reset_list_mutex); for (i = 0; i < resets->num_rstcs; i++) __reset_control_put_internal(resets->rstc[i]); mutex_unlock(&reset_list_mutex); } /** * reset_control_put - free the reset controller * @rstc: reset controller */ void reset_control_put(struct reset_control *rstc) { if (IS_ERR_OR_NULL(rstc)) return; if (reset_control_is_array(rstc)) { reset_control_array_put(rstc_to_array(rstc)); return; } mutex_lock(&reset_list_mutex); __reset_control_put_internal(rstc); mutex_unlock(&reset_list_mutex); } EXPORT_SYMBOL_GPL(reset_control_put); static void devm_reset_control_release(struct device *dev, void *res) { reset_control_put(*(struct reset_control **)res); } struct reset_control *__devm_reset_control_get(struct device *dev, const char *id, int index, bool shared, bool optional, bool acquired) { struct reset_control **ptr, *rstc; ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); rstc = __reset_control_get(dev, id, index, shared, optional, acquired); if (!IS_ERR(rstc)) { *ptr = rstc; devres_add(dev, ptr); } else { devres_free(ptr); } return rstc; } EXPORT_SYMBOL_GPL(__devm_reset_control_get); /** * device_reset - find reset controller associated with the device * and perform reset * @dev: device to be reset by the controller * @optional: whether it is optional to reset the device * * Convenience wrapper for __reset_control_get() and reset_control_reset(). * This is useful for the common case of devices with single, dedicated reset * lines. */ int __device_reset(struct device *dev, bool optional) { struct reset_control *rstc; int ret; rstc = __reset_control_get(dev, NULL, 0, 0, optional, true); if (IS_ERR(rstc)) return PTR_ERR(rstc); ret = reset_control_reset(rstc); reset_control_put(rstc); return ret; } EXPORT_SYMBOL_GPL(__device_reset); /** * APIs to manage an array of reset controls. */ /** * of_reset_control_get_count - Count number of resets available with a device * * @node: device node that contains 'resets'. * * Returns positive reset count on success, or error number on failure and * on count being zero. */ static int of_reset_control_get_count(struct device_node *node) { int count; if (!node) return -EINVAL; count = of_count_phandle_with_args(node, "resets", "#reset-cells"); if (count == 0) count = -ENOENT; return count; } /** * of_reset_control_array_get - Get a list of reset controls using * device node. * * @np: device node for the device that requests the reset controls array * @shared: whether reset controls are shared or not * @optional: whether it is optional to get the reset controls * @acquired: only one reset control may be acquired for a given controller * and ID * * Returns pointer to allocated reset_control_array on success or * error on failure */ struct reset_control * of_reset_control_array_get(struct device_node *np, bool shared, bool optional, bool acquired) { struct reset_control_array *resets; struct reset_control *rstc; int num, i; num = of_reset_control_get_count(np); if (num < 0) return optional ? NULL : ERR_PTR(num); resets = kzalloc(struct_size(resets, rstc, num), GFP_KERNEL); if (!resets) return ERR_PTR(-ENOMEM); for (i = 0; i < num; i++) { rstc = __of_reset_control_get(np, NULL, i, shared, optional, acquired); if (IS_ERR(rstc)) goto err_rst; resets->rstc[i] = rstc; } resets->num_rstcs = num; resets->base.array = true; return &resets->base; err_rst: mutex_lock(&reset_list_mutex); while (--i >= 0) __reset_control_put_internal(resets->rstc[i]); mutex_unlock(&reset_list_mutex); kfree(resets); return rstc; } EXPORT_SYMBOL_GPL(of_reset_control_array_get); /** * devm_reset_control_array_get - Resource managed reset control array get * * @dev: device that requests the list of reset controls * @shared: whether reset controls are shared or not * @optional: whether it is optional to get the reset controls * * The reset control array APIs are intended for a list of resets * that just have to be asserted or deasserted, without any * requirements on the order. * * Returns pointer to allocated reset_control_array on success or * error on failure */ struct reset_control * devm_reset_control_array_get(struct device *dev, bool shared, bool optional) { struct reset_control **devres; struct reset_control *rstc; devres = devres_alloc(devm_reset_control_release, sizeof(*devres), GFP_KERNEL); if (!devres) return ERR_PTR(-ENOMEM); rstc = of_reset_control_array_get(dev->of_node, shared, optional, true); if (IS_ERR(rstc)) { devres_free(devres); return rstc; } *devres = rstc; devres_add(dev, devres); return rstc; } EXPORT_SYMBOL_GPL(devm_reset_control_array_get); static int reset_control_get_count_from_lookup(struct device *dev) { const struct reset_control_lookup *lookup; const char *dev_id; int count = 0; if (!dev) return -EINVAL; dev_id = dev_name(dev); mutex_lock(&reset_lookup_mutex); list_for_each_entry(lookup, &reset_lookup_list, list) { if (!strcmp(lookup->dev_id, dev_id)) count++; } mutex_unlock(&reset_lookup_mutex); if (count == 0) count = -ENOENT; return count; } /** * reset_control_get_count - Count number of resets available with a device * * @dev: device for which to return the number of resets * * Returns positive reset count on success, or error number on failure and * on count being zero. */ int reset_control_get_count(struct device *dev) { if (dev->of_node) return of_reset_control_get_count(dev->of_node); return reset_control_get_count_from_lookup(dev); } EXPORT_SYMBOL_GPL(reset_control_get_count);