drivers/leds/led-class.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * LED Class Core
  *
  * Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
  * Copyright (C) 2005-2007 Richard Purdie <rpurdie@openedhand.com>
  */

 #include <linux/ctype.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/leds.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/property.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/timer.h>
 #include <uapi/linux/uleds.h>
 #include <linux/of.h>
 #include "leds.h"

 static struct class *leds_class;

 static ssize_t brightness_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);

 	/* no lock needed for this */
 	led_update_brightness(led_cdev);

 	return sprintf(buf, "%u\n", led_cdev->brightness);
 }

 static ssize_t brightness_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t size)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);
 	unsigned long state;
 	ssize_t ret;

 	mutex_lock(&led_cdev->led_access);

 	if (led_sysfs_is_disabled(led_cdev)) {
 		ret = -EBUSY;
 		goto unlock;
 	}

 	ret = kstrtoul(buf, 10, &state);
 	if (ret)
 		goto unlock;

 	if (state == LED_OFF)
 		led_trigger_remove(led_cdev);
 	led_set_brightness(led_cdev, state);
 	flush_work(&led_cdev->set_brightness_work);

 	ret = size;
 unlock:
 	mutex_unlock(&led_cdev->led_access);
 	return ret;
 }
 static DEVICE_ATTR_RW(brightness);

 static ssize_t max_brightness_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);

 	return sprintf(buf, "%u\n", led_cdev->max_brightness);
 }
 static DEVICE_ATTR_RO(max_brightness);

 #ifdef CONFIG_LEDS_TRIGGERS
 static BIN_ATTR(trigger, 0644, led_trigger_read, led_trigger_write, 0);
 static struct bin_attribute *led_trigger_bin_attrs[] = {
 	&bin_attr_trigger,
 	NULL,
 };
 static const struct attribute_group led_trigger_group = {
 	.bin_attrs = led_trigger_bin_attrs,
 };
 #endif

 static struct attribute *led_class_attrs[] = {
 	&dev_attr_brightness.attr,
 	&dev_attr_max_brightness.attr,
 	NULL,
 };

 static const struct attribute_group led_group = {
 	.attrs = led_class_attrs,
 };

 static const struct attribute_group *led_groups[] = {
 	&led_group,
 #ifdef CONFIG_LEDS_TRIGGERS
 	&led_trigger_group,
 #endif
 	NULL,
 };

 #ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
 static ssize_t brightness_hw_changed_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);

 	if (led_cdev->brightness_hw_changed == -1)
 		return -ENODATA;

 	return sprintf(buf, "%u\n", led_cdev->brightness_hw_changed);
 }

 static DEVICE_ATTR_RO(brightness_hw_changed);

 static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
 {
 	struct device *dev = led_cdev->dev;
 	int ret;

 	ret = device_create_file(dev, &dev_attr_brightness_hw_changed);
 	if (ret) {
 		dev_err(dev, "Error creating brightness_hw_changed\n");
 		return ret;
 	}

 	led_cdev->brightness_hw_changed_kn =
 		sysfs_get_dirent(dev->kobj.sd, "brightness_hw_changed");
 	if (!led_cdev->brightness_hw_changed_kn) {
 		dev_err(dev, "Error getting brightness_hw_changed kn\n");
 		device_remove_file(dev, &dev_attr_brightness_hw_changed);
 		return -ENXIO;
 	}

 	return 0;
 }

 static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
 {
 	sysfs_put(led_cdev->brightness_hw_changed_kn);
 	device_remove_file(led_cdev->dev, &dev_attr_brightness_hw_changed);
 }

 void led_classdev_notify_brightness_hw_changed(struct led_classdev *led_cdev, unsigned int brightness)
 {
 	if (WARN_ON(!led_cdev->brightness_hw_changed_kn))
 		return;

 	led_cdev->brightness_hw_changed = brightness;
 	sysfs_notify_dirent(led_cdev->brightness_hw_changed_kn);
 }
 EXPORT_SYMBOL_GPL(led_classdev_notify_brightness_hw_changed);
 #else
 static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
 {
 	return 0;
 }
 static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
 {
 }
 #endif

 /**
  * led_classdev_suspend - suspend an led_classdev.
  * @led_cdev: the led_classdev to suspend.
  */
 void led_classdev_suspend(struct led_classdev *led_cdev)
 {
 	led_cdev->flags |= LED_SUSPENDED;
 	led_set_brightness_nopm(led_cdev, 0);
 	flush_work(&led_cdev->set_brightness_work);
 }
 EXPORT_SYMBOL_GPL(led_classdev_suspend);

 /**
  * led_classdev_resume - resume an led_classdev.
  * @led_cdev: the led_classdev to resume.
  */
 void led_classdev_resume(struct led_classdev *led_cdev)
 {
 	led_set_brightness_nopm(led_cdev, led_cdev->brightness);

 	if (led_cdev->flash_resume)
 		led_cdev->flash_resume(led_cdev);

 	led_cdev->flags &= ~LED_SUSPENDED;
 }
 EXPORT_SYMBOL_GPL(led_classdev_resume);

 #ifdef CONFIG_PM_SLEEP
 static int led_suspend(struct device *dev)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);

 	if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 		led_classdev_suspend(led_cdev);

 	return 0;
 }

 static int led_resume(struct device *dev)
 {
 	struct led_classdev *led_cdev = dev_get_drvdata(dev);

 	if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
 		led_classdev_resume(led_cdev);

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);

 /**
  * of_led_get() - request a LED device via the LED framework
  * @np: device node to get the LED device from
  * @index: the index of the LED
  *
  * Returns the LED device parsed from the phandle specified in the "leds"
  * property of a device tree node or a negative error-code on failure.
  */
 struct led_classdev *of_led_get(struct device_node *np, int index)
 {
 	struct device *led_dev;
 	struct led_classdev *led_cdev;
 	struct device_node *led_node;

 	led_node = of_parse_phandle(np, "leds", index);
 	if (!led_node)
 		return ERR_PTR(-ENOENT);

 	led_dev = class_find_device_by_of_node(leds_class, led_node);
 	of_node_put(led_node);

 	if (!led_dev)
 		return ERR_PTR(-EPROBE_DEFER);

 	led_cdev = dev_get_drvdata(led_dev);

 	if (!try_module_get(led_cdev->dev->parent->driver->owner))
 		return ERR_PTR(-ENODEV);

 	return led_cdev;
 }
 EXPORT_SYMBOL_GPL(of_led_get);

 /**
  * led_put() - release a LED device
  * @led_cdev: LED device
  */
 void led_put(struct led_classdev *led_cdev)
 {
 	module_put(led_cdev->dev->parent->driver->owner);
 }
 EXPORT_SYMBOL_GPL(led_put);

 static void devm_led_release(struct device *dev, void *res)
 {
 	struct led_classdev **p = res;

 	led_put(*p);
 }

 /**
  * devm_of_led_get - Resource-managed request of a LED device
  * @dev:	LED consumer
  * @index:	index of the LED to obtain in the consumer
  *
  * The device node of the device is parse to find the request LED device.
  * The LED device returned from this function is automatically released
  * on driver detach.
  *
  * @return a pointer to a LED device or ERR_PTR(errno) on failure.
  */
 struct led_classdev *__must_check devm_of_led_get(struct device *dev,
 						  int index)
 {
 	struct led_classdev *led;
 	struct led_classdev **dr;

 	if (!dev)
 		return ERR_PTR(-EINVAL);

 	/* Not using device tree? */
 	if (!IS_ENABLED(CONFIG_OF) || !dev->of_node)
 		return ERR_PTR(-ENOTSUPP);

 	led = of_led_get(dev->of_node, index);
 	if (IS_ERR(led))
 		return led;

 	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
 			  GFP_KERNEL);
 	if (!dr) {
 		led_put(led);
 		return ERR_PTR(-ENOMEM);
 	}

 	*dr = led;
 	devres_add(dev, dr);

 	return led;
 }
 EXPORT_SYMBOL_GPL(devm_of_led_get);

 static int led_classdev_next_name(const char *init_name, char *name,
 				  size_t len)
 {
 	unsigned int i = 0;
 	int ret = 0;
 	struct device *dev;

 	strlcpy(name, init_name, len);

 	while ((ret < len) &&
 	       (dev = class_find_device_by_name(leds_class, name))) {
 		put_device(dev);
 		ret = snprintf(name, len, "%s_%u", init_name, ++i);
 	}

 	if (ret >= len)
 		return -ENOMEM;

 	return i;
 }

 /**
  * led_classdev_register_ext - register a new object of led_classdev class
  *			       with init data.
  *
  * @parent: parent of LED device
  * @led_cdev: the led_classdev structure for this device.
  * @init_data: LED class device initialization data
  */
 int led_classdev_register_ext(struct device *parent,
 			      struct led_classdev *led_cdev,
 			      struct led_init_data *init_data)
 {
 	char composed_name[LED_MAX_NAME_SIZE];
 	char final_name[LED_MAX_NAME_SIZE];
 	const char *proposed_name = composed_name;
 	int ret;

 	if (init_data) {
 		if (init_data->devname_mandatory && !init_data->devicename) {
 			dev_err(parent, "Mandatory device name is missing");
 			return -EINVAL;
 		}
 		ret = led_compose_name(parent, init_data, composed_name);
 		if (ret < 0)
 			return ret;

 		if (init_data->fwnode)
 			fwnode_property_read_string(init_data->fwnode,
 				"linux,default-trigger",
 				&led_cdev->default_trigger);
 	} else {
 		proposed_name = led_cdev->name;
 	}

 	ret = led_classdev_next_name(proposed_name, final_name, sizeof(final_name));
 	if (ret < 0)
 		return ret;

 	mutex_init(&led_cdev->led_access);
 	mutex_lock(&led_cdev->led_access);
 	led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
 				led_cdev, led_cdev->groups, "%s", final_name);
 	if (IS_ERR(led_cdev->dev)) {
 		mutex_unlock(&led_cdev->led_access);
 		return PTR_ERR(led_cdev->dev);
 	}
 	if (init_data && init_data->fwnode) {
 		led_cdev->dev->fwnode = init_data->fwnode;
 		led_cdev->dev->of_node = to_of_node(init_data->fwnode);
 	}

 	if (ret)
 		dev_warn(parent, "Led %s renamed to %s due to name collision",
 				proposed_name, dev_name(led_cdev->dev));

 	if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
 		ret = led_add_brightness_hw_changed(led_cdev);
 		if (ret) {
 			device_unregister(led_cdev->dev);
 			led_cdev->dev = NULL;
 			mutex_unlock(&led_cdev->led_access);
 			return ret;
 		}
 	}

 	led_cdev->work_flags = 0;
 #ifdef CONFIG_LEDS_TRIGGERS
 	init_rwsem(&led_cdev->trigger_lock);
 #endif
 #ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
 	led_cdev->brightness_hw_changed = -1;
 #endif
 	/* add to the list of leds */
 	down_write(&leds_list_lock);
 	list_add_tail(&led_cdev->node, &leds_list);
 	up_write(&leds_list_lock);

 	if (!led_cdev->max_brightness)
 		led_cdev->max_brightness = LED_FULL;

 	led_update_brightness(led_cdev);

 	led_init_core(led_cdev);

 #ifdef CONFIG_LEDS_TRIGGERS
 	led_trigger_set_default(led_cdev);
 #endif

 	mutex_unlock(&led_cdev->led_access);

 	dev_dbg(parent, "Registered led device: %s\n",
 			led_cdev->name);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(led_classdev_register_ext);

 /**
  * led_classdev_unregister - unregisters a object of led_properties class.
  * @led_cdev: the led device to unregister
  *
  * Unregisters a previously registered via led_classdev_register object.
  */
 void led_classdev_unregister(struct led_classdev *led_cdev)
 {
 	if (IS_ERR_OR_NULL(led_cdev->dev))
 		return;

 #ifdef CONFIG_LEDS_TRIGGERS
 	down_write(&led_cdev->trigger_lock);
 	if (led_cdev->trigger)
 		led_trigger_set(led_cdev, NULL);
 	up_write(&led_cdev->trigger_lock);
 #endif

 	led_cdev->flags |= LED_UNREGISTERING;

 	/* Stop blinking */
 	led_stop_software_blink(led_cdev);

 	led_set_brightness(led_cdev, LED_OFF);

 	flush_work(&led_cdev->set_brightness_work);

 	if (led_cdev->flags & LED_BRIGHT_HW_CHANGED)
 		led_remove_brightness_hw_changed(led_cdev);

 	device_unregister(led_cdev->dev);

 	down_write(&leds_list_lock);
 	list_del(&led_cdev->node);
 	up_write(&leds_list_lock);

 	mutex_destroy(&led_cdev->led_access);
 }
 EXPORT_SYMBOL_GPL(led_classdev_unregister);

 static void devm_led_classdev_release(struct device *dev, void *res)
 {
 	led_classdev_unregister(*(struct led_classdev **)res);
 }

 /**
  * devm_led_classdev_register_ext - resource managed led_classdev_register_ext()
  *
  * @parent: parent of LED device
  * @led_cdev: the led_classdev structure for this device.
  * @init_data: LED class device initialization data
  */
 int devm_led_classdev_register_ext(struct device *parent,
 				   struct led_classdev *led_cdev,
 				   struct led_init_data *init_data)
 {
 	struct led_classdev **dr;
 	int rc;

 	dr = devres_alloc(devm_led_classdev_release, sizeof(*dr), GFP_KERNEL);
 	if (!dr)
 		return -ENOMEM;

 	rc = led_classdev_register_ext(parent, led_cdev, init_data);
 	if (rc) {
 		devres_free(dr);
 		return rc;
 	}

 	*dr = led_cdev;
 	devres_add(parent, dr);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(devm_led_classdev_register_ext);

 static int devm_led_classdev_match(struct device *dev, void *res, void *data)
 {
 	struct led_classdev **p = res;

 	if (WARN_ON(!p || !*p))
 		return 0;

 	return *p == data;
 }

 /**
  * devm_led_classdev_unregister() - resource managed led_classdev_unregister()
  * @parent: The device to unregister.
  * @led_cdev: the led_classdev structure for this device.
  */
 void devm_led_classdev_unregister(struct device *dev,
 				  struct led_classdev *led_cdev)
 {
 	WARN_ON(devres_release(dev,
 			       devm_led_classdev_release,
 			       devm_led_classdev_match, led_cdev));
 }
 EXPORT_SYMBOL_GPL(devm_led_classdev_unregister);

 static int __init leds_init(void)
 {
 	leds_class = class_create(THIS_MODULE, "leds");
 	if (IS_ERR(leds_class))
 		return PTR_ERR(leds_class);
 	leds_class->pm = &leds_class_dev_pm_ops;
 	leds_class->dev_groups = led_groups;
 	return 0;
 }

 static void __exit leds_exit(void)
 {
 	class_destroy(leds_class);
 }

 subsys_initcall(leds_init);
 module_exit(leds_exit);

 MODULE_AUTHOR("John Lenz, Richard Purdie");
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("LED Class Interface");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* LED Class Core
	*
	* Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
	* Copyright (C) 2005-2007 Richard Purdie <rpurdie@openedhand.com>
	*/

	#include <linux/ctype.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/leds.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/property.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <linux/timer.h>
	#include <uapi/linux/uleds.h>
	#include <linux/of.h>
	#include "leds.h"

	static struct class *leds_class;

	static ssize_t brightness_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct led_classdev *led_cdev = dev_get_drvdata(dev);

	/* no lock needed for this */
	led_update_brightness(led_cdev);

	return sprintf(buf, "%u\n", led_cdev->brightness);
	}

	static ssize_t brightness_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t size)
	{
	struct led_classdev *led_cdev = dev_get_drvdata(dev);
	unsigned long state;
	ssize_t ret;

	mutex_lock(&led_cdev->led_access);

	if (led_sysfs_is_disabled(led_cdev)) {
	ret = -EBUSY;
	goto unlock;
	}

	ret = kstrtoul(buf, 10, &state);
	if (ret)
	goto unlock;

	if (state == LED_OFF)
	led_trigger_remove(led_cdev);
	led_set_brightness(led_cdev, state);
	flush_work(&led_cdev->set_brightness_work);

	ret = size;
	unlock:
	mutex_unlock(&led_cdev->led_access);
	return ret;
	}
	static DEVICE_ATTR_RW(brightness);

	static ssize_t max_brightness_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct led_classdev *led_cdev = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", led_cdev->max_brightness);
	}
	static DEVICE_ATTR_RO(max_brightness);

	#ifdef CONFIG_LEDS_TRIGGERS
	static BIN_ATTR(trigger, 0644, led_trigger_read, led_trigger_write, 0);
	static struct bin_attribute *led_trigger_bin_attrs[] = {
	&bin_attr_trigger,
	NULL,
	};
	static const struct attribute_group led_trigger_group = {
	.bin_attrs = led_trigger_bin_attrs,
	};
	#endif

	static struct attribute *led_class_attrs[] = {
	&dev_attr_brightness.attr,
	&dev_attr_max_brightness.attr,
	NULL,
	};

	static const struct attribute_group led_group = {
	.attrs = led_class_attrs,
	};

	static const struct attribute_group *led_groups[] = {
	&led_group,
	#ifdef CONFIG_LEDS_TRIGGERS
	&led_trigger_group,
	#endif
	NULL,
	};

	#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
	static ssize_t brightness_hw_changed_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct led_classdev *led_cdev = dev_get_drvdata(dev);

	if (led_cdev->brightness_hw_changed == -1)
	return -ENODATA;

	return sprintf(buf, "%u\n", led_cdev->brightness_hw_changed);
	}

	static DEVICE_ATTR_RO(brightness_hw_changed);

	static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
	{
	struct device *dev = led_cdev->dev;
	int ret;

	ret = device_create_file(dev, &dev_attr_brightness_hw_changed);
	if (ret) {
	dev_err(dev, "Error creating brightness_hw_changed\n");
	return ret;
	}

	led_cdev->brightness_hw_changed_kn =
	sysfs_get_dirent(dev->kobj.sd, "brightness_hw_changed");
	if (!led_cdev->brightness_hw_changed_kn) {
	dev_err(dev, "Error getting brightness_hw_changed kn\n");
	device_remove_file(dev, &dev_attr_brightness_hw_changed);
	return -ENXIO;
	}

	return 0;
	}

	static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
	{
	sysfs_put(led_cdev->brightness_hw_changed_kn);
	device_remove_file(led_cdev->dev, &dev_attr_brightness_hw_changed);
	}

	void led_classdev_notify_brightness_hw_changed(struct led_classdev *led_cdev, unsigned int brightness)
	{
	if (WARN_ON(!led_cdev->brightness_hw_changed_kn))
	return;

	led_cdev->brightness_hw_changed = brightness;
	sysfs_notify_dirent(led_cdev->brightness_hw_changed_kn);
	}
	EXPORT_SYMBOL_GPL(led_classdev_notify_brightness_hw_changed);
	#else
	static int led_add_brightness_hw_changed(struct led_classdev *led_cdev)
	{
	return 0;
	}
	static void led_remove_brightness_hw_changed(struct led_classdev *led_cdev)
	{
	}
	#endif

	/**
	* led_classdev_suspend - suspend an led_classdev.
	* @led_cdev: the led_classdev to suspend.
	*/
	void led_classdev_suspend(struct led_classdev *led_cdev)
	{
	led_cdev->flags \|= LED_SUSPENDED;
	led_set_brightness_nopm(led_cdev, 0);
	flush_work(&led_cdev->set_brightness_work);
	}
	EXPORT_SYMBOL_GPL(led_classdev_suspend);

	/**
	* led_classdev_resume - resume an led_classdev.
	* @led_cdev: the led_classdev to resume.
	*/
	void led_classdev_resume(struct led_classdev *led_cdev)
	{
	led_set_brightness_nopm(led_cdev, led_cdev->brightness);

	if (led_cdev->flash_resume)
	led_cdev->flash_resume(led_cdev);

	led_cdev->flags &= ~LED_SUSPENDED;
	}
	EXPORT_SYMBOL_GPL(led_classdev_resume);

	#ifdef CONFIG_PM_SLEEP
	static int led_suspend(struct device *dev)
	{
	struct led_classdev *led_cdev = dev_get_drvdata(dev);

	if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
	led_classdev_suspend(led_cdev);

	return 0;
	}

	static int led_resume(struct device *dev)
	{
	struct led_classdev *led_cdev = dev_get_drvdata(dev);

	if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
	led_classdev_resume(led_cdev);

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);

	/**
	* of_led_get() - request a LED device via the LED framework
	* @np: device node to get the LED device from
	* @index: the index of the LED
	*
	* Returns the LED device parsed from the phandle specified in the "leds"
	* property of a device tree node or a negative error-code on failure.
	*/
	struct led_classdev of_led_get(struct device_node np, int index)
	{
	struct device *led_dev;
	struct led_classdev *led_cdev;
	struct device_node *led_node;

	led_node = of_parse_phandle(np, "leds", index);
	if (!led_node)
	return ERR_PTR(-ENOENT);

	led_dev = class_find_device_by_of_node(leds_class, led_node);
	of_node_put(led_node);

	if (!led_dev)
	return ERR_PTR(-EPROBE_DEFER);

	led_cdev = dev_get_drvdata(led_dev);

	if (!try_module_get(led_cdev->dev->parent->driver->owner))
	return ERR_PTR(-ENODEV);

	return led_cdev;
	}
	EXPORT_SYMBOL_GPL(of_led_get);

	/**
	* led_put() - release a LED device
	* @led_cdev: LED device
	*/
	void led_put(struct led_classdev *led_cdev)
	{
	module_put(led_cdev->dev->parent->driver->owner);
	}
	EXPORT_SYMBOL_GPL(led_put);

	static void devm_led_release(struct device dev, void res)
	{
	struct led_classdev **p = res;

	led_put(*p);
	}

	/**
	* devm_of_led_get - Resource-managed request of a LED device
	* @dev: LED consumer
	* @index: index of the LED to obtain in the consumer
	*
	* The device node of the device is parse to find the request LED device.
	* The LED device returned from this function is automatically released
	* on driver detach.
	*
	* @return a pointer to a LED device or ERR_PTR(errno) on failure.
	*/
	struct led_classdev __must_check devm_of_led_get(struct device dev,
	int index)
	{
	struct led_classdev *led;
	struct led_classdev **dr;

	if (!dev)
	return ERR_PTR(-EINVAL);

	/* Not using device tree? */
	if (!IS_ENABLED(CONFIG_OF) \|\| !dev->of_node)
	return ERR_PTR(-ENOTSUPP);

	led = of_led_get(dev->of_node, index);
	if (IS_ERR(led))
	return led;

	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
	GFP_KERNEL);
	if (!dr) {
	led_put(led);
	return ERR_PTR(-ENOMEM);
	}

	*dr = led;
	devres_add(dev, dr);

	return led;
	}
	EXPORT_SYMBOL_GPL(devm_of_led_get);

	static int led_classdev_next_name(const char init_name, char name,
	size_t len)
	{
	unsigned int i = 0;
	int ret = 0;
	struct device *dev;

	strlcpy(name, init_name, len);

	while ((ret < len) &&
	(dev = class_find_device_by_name(leds_class, name))) {
	put_device(dev);
	ret = snprintf(name, len, "%s_%u", init_name, ++i);
	}

	if (ret >= len)
	return -ENOMEM;

	return i;
	}

	/**
	* led_classdev_register_ext - register a new object of led_classdev class
	* with init data.
	*
	* @parent: parent of LED device
	* @led_cdev: the led_classdev structure for this device.
	* @init_data: LED class device initialization data
	*/
	int led_classdev_register_ext(struct device *parent,
	struct led_classdev *led_cdev,
	struct led_init_data *init_data)
	{
	char composed_name[LED_MAX_NAME_SIZE];
	char final_name[LED_MAX_NAME_SIZE];
	const char *proposed_name = composed_name;
	int ret;

	if (init_data) {
	if (init_data->devname_mandatory && !init_data->devicename) {
	dev_err(parent, "Mandatory device name is missing");
	return -EINVAL;
	}
	ret = led_compose_name(parent, init_data, composed_name);
	if (ret < 0)
	return ret;

	if (init_data->fwnode)
	fwnode_property_read_string(init_data->fwnode,
	"linux,default-trigger",
	&led_cdev->default_trigger);
	} else {
	proposed_name = led_cdev->name;
	}

	ret = led_classdev_next_name(proposed_name, final_name, sizeof(final_name));
	if (ret < 0)
	return ret;

	mutex_init(&led_cdev->led_access);
	mutex_lock(&led_cdev->led_access);
	led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
	led_cdev, led_cdev->groups, "%s", final_name);
	if (IS_ERR(led_cdev->dev)) {
	mutex_unlock(&led_cdev->led_access);
	return PTR_ERR(led_cdev->dev);
	}
	if (init_data && init_data->fwnode) {
	led_cdev->dev->fwnode = init_data->fwnode;
	led_cdev->dev->of_node = to_of_node(init_data->fwnode);
	}

	if (ret)
	dev_warn(parent, "Led %s renamed to %s due to name collision",
	proposed_name, dev_name(led_cdev->dev));

	if (led_cdev->flags & LED_BRIGHT_HW_CHANGED) {
	ret = led_add_brightness_hw_changed(led_cdev);
	if (ret) {
	device_unregister(led_cdev->dev);
	led_cdev->dev = NULL;
	mutex_unlock(&led_cdev->led_access);
	return ret;
	}
	}

	led_cdev->work_flags = 0;
	#ifdef CONFIG_LEDS_TRIGGERS
	init_rwsem(&led_cdev->trigger_lock);
	#endif
	#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
	led_cdev->brightness_hw_changed = -1;
	#endif
	/* add to the list of leds */
	down_write(&leds_list_lock);
	list_add_tail(&led_cdev->node, &leds_list);
	up_write(&leds_list_lock);

	if (!led_cdev->max_brightness)
	led_cdev->max_brightness = LED_FULL;

	led_update_brightness(led_cdev);

	led_init_core(led_cdev);

	#ifdef CONFIG_LEDS_TRIGGERS
	led_trigger_set_default(led_cdev);
	#endif

	mutex_unlock(&led_cdev->led_access);

	dev_dbg(parent, "Registered led device: %s\n",
	led_cdev->name);

	return 0;
	}
	EXPORT_SYMBOL_GPL(led_classdev_register_ext);

	/**
	* led_classdev_unregister - unregisters a object of led_properties class.
	* @led_cdev: the led device to unregister
	*
	* Unregisters a previously registered via led_classdev_register object.
	*/
	void led_classdev_unregister(struct led_classdev *led_cdev)
	{
	if (IS_ERR_OR_NULL(led_cdev->dev))
	return;

	#ifdef CONFIG_LEDS_TRIGGERS
	down_write(&led_cdev->trigger_lock);
	if (led_cdev->trigger)
	led_trigger_set(led_cdev, NULL);
	up_write(&led_cdev->trigger_lock);
	#endif

	led_cdev->flags \|= LED_UNREGISTERING;

	/* Stop blinking */
	led_stop_software_blink(led_cdev);

	led_set_brightness(led_cdev, LED_OFF);

	flush_work(&led_cdev->set_brightness_work);

	if (led_cdev->flags & LED_BRIGHT_HW_CHANGED)
	led_remove_brightness_hw_changed(led_cdev);

	device_unregister(led_cdev->dev);

	down_write(&leds_list_lock);
	list_del(&led_cdev->node);
	up_write(&leds_list_lock);

	mutex_destroy(&led_cdev->led_access);
	}
	EXPORT_SYMBOL_GPL(led_classdev_unregister);

	static void devm_led_classdev_release(struct device dev, void res)
	{
	led_classdev_unregister((struct led_classdev *)res);
	}

	/**
	* devm_led_classdev_register_ext - resource managed led_classdev_register_ext()
	*
	* @parent: parent of LED device
	* @led_cdev: the led_classdev structure for this device.
	* @init_data: LED class device initialization data
	*/
	int devm_led_classdev_register_ext(struct device *parent,
	struct led_classdev *led_cdev,
	struct led_init_data *init_data)
	{
	struct led_classdev **dr;
	int rc;

	dr = devres_alloc(devm_led_classdev_release, sizeof(*dr), GFP_KERNEL);
	if (!dr)
	return -ENOMEM;

	rc = led_classdev_register_ext(parent, led_cdev, init_data);
	if (rc) {
	devres_free(dr);
	return rc;
	}

	*dr = led_cdev;
	devres_add(parent, dr);

	return 0;
	}
	EXPORT_SYMBOL_GPL(devm_led_classdev_register_ext);

	static int devm_led_classdev_match(struct device dev, void res, void *data)
	{
	struct led_classdev **p = res;

	if (WARN_ON(!p \|\| !*p))
	return 0;

	return *p == data;
	}

	/**
	* devm_led_classdev_unregister() - resource managed led_classdev_unregister()
	* @parent: The device to unregister.
	* @led_cdev: the led_classdev structure for this device.
	*/
	void devm_led_classdev_unregister(struct device *dev,
	struct led_classdev *led_cdev)
	{
	WARN_ON(devres_release(dev,
	devm_led_classdev_release,
	devm_led_classdev_match, led_cdev));
	}
	EXPORT_SYMBOL_GPL(devm_led_classdev_unregister);

	static int __init leds_init(void)
	{
	leds_class = class_create(THIS_MODULE, "leds");
	if (IS_ERR(leds_class))
	return PTR_ERR(leds_class);
	leds_class->pm = &leds_class_dev_pm_ops;
	leds_class->dev_groups = led_groups;
	return 0;
	}

	static void __exit leds_exit(void)
	{
	class_destroy(leds_class);
	}

	subsys_initcall(leds_init);
	module_exit(leds_exit);

	MODULE_AUTHOR("John Lenz, Richard Purdie");
	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("LED Class Interface");