/* * Reset Controller framework * * Copyright 2013 Philipp Zabel, Pengutronix * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */#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); /** * 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 * @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 shared;	atomic_t deassert_count;	atomic_t triggered_count;}; /** * 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_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 (!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;	} 	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 (!rstc->rcdev->ops->assert)		return -ENOTSUPP; 	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;	} 	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 (!rstc->rcdev->ops->deassert)		return -ENOTSUPP; 	if (rstc->shared) {		if (WARN_ON(atomic_read(&rstc->triggered_count) != 0))			return -EINVAL; 		if (atomic_inc_return(&rstc->deassert_count) != 1)			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)))		return -EINVAL; 	if (rstc->rcdev->ops->status)		return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); 	return -ENOTSUPP;}EXPORT_SYMBOL_GPL(reset_control_status); static struct reset_control *__reset_control_get_internal(				struct reset_controller_dev *rcdev,				unsigned int index, bool shared){	struct reset_control *rstc; 	lockdep_assert_held(&reset_list_mutex); 	list_for_each_entry(rstc, &rcdev->reset_control_head, list) {		if (rstc->id == index) {			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->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){	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;		}	}	of_node_put(args.np); 	if (!rcdev) {		mutex_unlock(&reset_list_mutex);		return ERR_PTR(-EPROBE_DEFER);	} 	if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {		mutex_unlock(&reset_list_mutex);		return ERR_PTR(-EINVAL);	} 	rstc_id = rcdev->of_xlate(rcdev, &args);	if (rstc_id < 0) {		mutex_unlock(&reset_list_mutex);		return ERR_PTR(rstc_id);	} 	/* reset_list_mutex also protects the rcdev's reset_control list */	rstc = __reset_control_get_internal(rcdev, rstc_id, shared); 	mutex_unlock(&reset_list_mutex); 	return rstc;}EXPORT_SYMBOL_GPL(__of_reset_control_get); struct reset_control *__reset_control_get(struct device *dev, const char *id,					  int index, bool shared, bool optional){	if (dev->of_node)		return __of_reset_control_get(dev->of_node, id, index, shared,					      optional); 	return optional ? NULL : ERR_PTR(-EINVAL);}EXPORT_SYMBOL_GPL(__reset_control_get); /** * 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; 	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){	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);	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 * * 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){	struct reset_control *rstc;	int ret; 	rstc = reset_control_get(dev, NULL);	if (IS_ERR(rstc))		return PTR_ERR(rstc); 	ret = reset_control_reset(rstc); 	reset_control_put(rstc); 	return ret;}EXPORT_SYMBOL_GPL(device_reset);