// 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? * @array: Is this an array of reset controls (1)? * @deassert_count: 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 * * This static translation function is used by default if of_xlate in * :c:type:`reset_controller_dev` is not set. It is useful for all 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) {		devres_free(rcdevp);		return ret;	} 	*rcdevp = rcdev;	devres_add(dev, 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_rearm(struct reset_control_array *resets){	struct reset_control *rstc;	int i; 	for (i = 0; i < resets->num_rstcs; i++) {		rstc = resets->rstc[i]; 		if (!rstc)			continue; 		if (WARN_ON(IS_ERR(rstc)))			return -EINVAL; 		if (rstc->shared) {			if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))				return -EINVAL;		} else {			if (!rstc->acquired)				return -EPERM;		}	} 	for (i = 0; i < resets->num_rstcs; i++) {		rstc = resets->rstc[i]; 		if (rstc && rstc->shared)			WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);	} 	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_bulk_reset - reset the controlled devices in order * @num_rstcs: number of entries in rstcs array * @rstcs: array of struct reset_control_bulk_data with reset controls set * * Issue a reset on all provided reset controls, in order. * * See also: reset_control_reset() */int reset_control_bulk_reset(int num_rstcs,			     struct reset_control_bulk_data *rstcs){	int ret, i; 	for (i = 0; i < num_rstcs; i++) {		ret = reset_control_reset(rstcs[i].rstc);		if (ret)			return ret;	} 	return 0;}EXPORT_SYMBOL_GPL(reset_control_bulk_reset); /** * reset_control_rearm - allow shared reset line to be re-triggered" * @rstc: reset controller * * On a shared reset line the actual reset pulse is only triggered once for the * lifetime of the reset_control instance, except if this call is used. * * Calls to this function must be balanced with calls to reset_control_reset, * a warning is thrown in case triggered_count ever dips below 0. * * Consumers must not use reset_control_(de)assert on shared reset lines when * reset_control_reset or reset_control_rearm have been used. * * If rstc is NULL the function will just return 0. */int reset_control_rearm(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_rearm(rstc_to_array(rstc)); 	if (rstc->shared) {		if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))			return -EINVAL; 		WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);	} else {		if (!rstc->acquired)			return -EPERM;	} 	return 0;}EXPORT_SYMBOL_GPL(reset_control_rearm); /** * 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. * * 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_bulk_assert - asserts the reset lines in order * @num_rstcs: number of entries in rstcs array * @rstcs: array of struct reset_control_bulk_data with reset controls set * * Assert the reset lines for all provided reset controls, in order. * If an assertion fails, already asserted resets are deasserted again. * * See also: reset_control_assert() */int reset_control_bulk_assert(int num_rstcs,			      struct reset_control_bulk_data *rstcs){

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