drivers/video/backlight/backlight.c - kernel/msm-4.9 - Gitiles

 /*
  * Backlight Lowlevel Control Abstraction
  *
  * Copyright (C) 2003,2004 Hewlett-Packard Company
  *
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/device.h>
 #include <linux/backlight.h>
 #include <linux/notifier.h>
 #include <linux/ctype.h>
 #include <linux/err.h>
 #include <linux/fb.h>
 #include <linux/slab.h>

 #ifdef CONFIG_PMAC_BACKLIGHT
 #include <asm/backlight.h>
 #endif

 static const char *const backlight_types[] = {
 	[BACKLIGHT_RAW] = "raw",
 	[BACKLIGHT_PLATFORM] = "platform",
 	[BACKLIGHT_FIRMWARE] = "firmware",
 };

 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
 			   defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
 /* This callback gets called when something important happens inside a
  * framebuffer driver. We're looking if that important event is blanking,
  * and if it is, we're switching backlight power as well ...
  */
 static int fb_notifier_callback(struct notifier_block *self,
 				unsigned long event, void *data)
 {
 	struct backlight_device *bd;
 	struct fb_event *evdata = data;

 	/* If we aren't interested in this event, skip it immediately ... */
 	if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
 		return 0;

 	bd = container_of(self, struct backlight_device, fb_notif);
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops)
 		if (!bd->ops->check_fb ||
 		    bd->ops->check_fb(bd, evdata->info)) {
 			bd->props.fb_blank = *(int *)evdata->data;
 			if (bd->props.fb_blank == FB_BLANK_UNBLANK)
 				bd->props.state &= ~BL_CORE_FBBLANK;
 			else
 				bd->props.state |= BL_CORE_FBBLANK;
 			backlight_update_status(bd);
 		}
 	mutex_unlock(&bd->ops_lock);
 	return 0;
 }

 static int backlight_register_fb(struct backlight_device *bd)
 {
 	memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
 	bd->fb_notif.notifier_call = fb_notifier_callback;

 	return fb_register_client(&bd->fb_notif);
 }

 static void backlight_unregister_fb(struct backlight_device *bd)
 {
 	fb_unregister_client(&bd->fb_notif);
 }
 #else
 static inline int backlight_register_fb(struct backlight_device *bd)
 {
 	return 0;
 }

 static inline void backlight_unregister_fb(struct backlight_device *bd)
 {
 }
 #endif /* CONFIG_FB */

 static void backlight_generate_event(struct backlight_device *bd,
 				     enum backlight_update_reason reason)
 {
 	char *envp[2];

 	switch (reason) {
 	case BACKLIGHT_UPDATE_SYSFS:
 		envp[0] = "SOURCE=sysfs";
 		break;
 	case BACKLIGHT_UPDATE_HOTKEY:
 		envp[0] = "SOURCE=hotkey";
 		break;
 	default:
 		envp[0] = "SOURCE=unknown";
 		break;
 	}
 	envp[1] = NULL;
 	kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
 	sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
 }

 static ssize_t backlight_show_power(struct device *dev,
 		struct device_attribute *attr,char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);

 	return sprintf(buf, "%d\n", bd->props.power);
 }

 static ssize_t backlight_store_power(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	int rc;
 	struct backlight_device *bd = to_backlight_device(dev);
 	unsigned long power;

 	rc = strict_strtoul(buf, 0, &power);
 	if (rc)
 		return rc;

 	rc = -ENXIO;
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops) {
 		pr_debug("backlight: set power to %lu\n", power);
 		if (bd->props.power != power) {
 			bd->props.power = power;
 			backlight_update_status(bd);
 		}
 		rc = count;
 	}
 	mutex_unlock(&bd->ops_lock);

 	return rc;
 }

 static ssize_t backlight_show_brightness(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);

 	return sprintf(buf, "%d\n", bd->props.brightness);
 }

 static ssize_t backlight_store_brightness(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	int rc;
 	struct backlight_device *bd = to_backlight_device(dev);
 	unsigned long brightness;

 	rc = strict_strtoul(buf, 0, &brightness);
 	if (rc)
 		return rc;

 	rc = -ENXIO;

 	mutex_lock(&bd->ops_lock);
 	if (bd->ops) {
 		if (brightness > bd->props.max_brightness)
 			rc = -EINVAL;
 		else {
 			pr_debug("backlight: set brightness to %lu\n",
 				 brightness);
 			bd->props.brightness = brightness;
 			backlight_update_status(bd);
 			rc = count;
 		}
 	}
 	mutex_unlock(&bd->ops_lock);

 	backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);

 	return rc;
 }

 static ssize_t backlight_show_type(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);

 	return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
 }

 static ssize_t backlight_show_max_brightness(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct backlight_device *bd = to_backlight_device(dev);

 	return sprintf(buf, "%d\n", bd->props.max_brightness);
 }

 static ssize_t backlight_show_actual_brightness(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	int rc = -ENXIO;
 	struct backlight_device *bd = to_backlight_device(dev);

 	mutex_lock(&bd->ops_lock);
 	if (bd->ops && bd->ops->get_brightness)
 		rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 	mutex_unlock(&bd->ops_lock);

 	return rc;
 }

 static struct class *backlight_class;

 static int backlight_suspend(struct device *dev, pm_message_t state)
 {
 	struct backlight_device *bd = to_backlight_device(dev);

 	mutex_lock(&bd->ops_lock);
 	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 		bd->props.state |= BL_CORE_SUSPENDED;
 		backlight_update_status(bd);
 	}
 	mutex_unlock(&bd->ops_lock);

 	return 0;
 }

 static int backlight_resume(struct device *dev)
 {
 	struct backlight_device *bd = to_backlight_device(dev);

 	mutex_lock(&bd->ops_lock);
 	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 		bd->props.state &= ~BL_CORE_SUSPENDED;
 		backlight_update_status(bd);
 	}
 	mutex_unlock(&bd->ops_lock);

 	return 0;
 }

 static void bl_device_release(struct device *dev)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 	kfree(bd);
 }

 static struct device_attribute bl_device_attributes[] = {
 	__ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
 	__ATTR(brightness, 0644, backlight_show_brightness,
 		     backlight_store_brightness),
 	__ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 		     NULL),
 	__ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 	__ATTR(type, 0444, backlight_show_type, NULL),
 	__ATTR_NULL,
 };

 /**
  * backlight_force_update - tell the backlight subsystem that hardware state
  *   has changed
  * @bd: the backlight device to update
  *
  * Updates the internal state of the backlight in response to a hardware event,
  * and generate a uevent to notify userspace
  */
 void backlight_force_update(struct backlight_device *bd,
 			    enum backlight_update_reason reason)
 {
 	mutex_lock(&bd->ops_lock);
 	if (bd->ops && bd->ops->get_brightness)
 		bd->props.brightness = bd->ops->get_brightness(bd);
 	mutex_unlock(&bd->ops_lock);
 	backlight_generate_event(bd, reason);
 }
 EXPORT_SYMBOL(backlight_force_update);

 /**
  * backlight_device_register - create and register a new object of
  *   backlight_device class.
  * @name: the name of the new object(must be the same as the name of the
  *   respective framebuffer device).
  * @parent: a pointer to the parent device
  * @devdata: an optional pointer to be stored for private driver use. The
  *   methods may retrieve it by using bl_get_data(bd).
  * @ops: the backlight operations structure.
  *
  * Creates and registers new backlight device. Returns either an
  * ERR_PTR() or a pointer to the newly allocated device.
  */
 struct backlight_device *backlight_device_register(const char *name,
 	struct device *parent, void *devdata, const struct backlight_ops *ops,
 	const struct backlight_properties *props)
 {
 	struct backlight_device *new_bd;
 	int rc;

 	pr_debug("backlight_device_register: name=%s\n", name);

 	new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 	if (!new_bd)
 		return ERR_PTR(-ENOMEM);

 	mutex_init(&new_bd->update_lock);
 	mutex_init(&new_bd->ops_lock);

 	new_bd->dev.class = backlight_class;
 	new_bd->dev.parent = parent;
 	new_bd->dev.release = bl_device_release;
 	dev_set_name(&new_bd->dev, name);
 	dev_set_drvdata(&new_bd->dev, devdata);

 	/* Set default properties */
 	if (props) {
 		memcpy(&new_bd->props, props,
 		       sizeof(struct backlight_properties));
 		if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
 			WARN(1, "%s: invalid backlight type", name);
 			new_bd->props.type = BACKLIGHT_RAW;
 		}
 	} else {
 		new_bd->props.type = BACKLIGHT_RAW;
 	}

 	rc = device_register(&new_bd->dev);
 	if (rc) {
 		kfree(new_bd);
 		return ERR_PTR(rc);
 	}

 	rc = backlight_register_fb(new_bd);
 	if (rc) {
 		device_unregister(&new_bd->dev);
 		return ERR_PTR(rc);
 	}

 	new_bd->ops = ops;

 #ifdef CONFIG_PMAC_BACKLIGHT
 	mutex_lock(&pmac_backlight_mutex);
 	if (!pmac_backlight)
 		pmac_backlight = new_bd;
 	mutex_unlock(&pmac_backlight_mutex);
 #endif

 	return new_bd;
 }
 EXPORT_SYMBOL(backlight_device_register);

 /**
  * backlight_device_unregister - unregisters a backlight device object.
  * @bd: the backlight device object to be unregistered and freed.
  *
  * Unregisters a previously registered via backlight_device_register object.
  */
 void backlight_device_unregister(struct backlight_device *bd)
 {
 	if (!bd)
 		return;

 #ifdef CONFIG_PMAC_BACKLIGHT
 	mutex_lock(&pmac_backlight_mutex);
 	if (pmac_backlight == bd)
 		pmac_backlight = NULL;
 	mutex_unlock(&pmac_backlight_mutex);
 #endif
 	mutex_lock(&bd->ops_lock);
 	bd->ops = NULL;
 	mutex_unlock(&bd->ops_lock);

 	backlight_unregister_fb(bd);
 	device_unregister(&bd->dev);
 }
 EXPORT_SYMBOL(backlight_device_unregister);

 static void __exit backlight_class_exit(void)
 {
 	class_destroy(backlight_class);
 }

 static int __init backlight_class_init(void)
 {
 	backlight_class = class_create(THIS_MODULE, "backlight");
 	if (IS_ERR(backlight_class)) {
 		printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
 				PTR_ERR(backlight_class));
 		return PTR_ERR(backlight_class);
 	}

 	backlight_class->dev_attrs = bl_device_attributes;
 	backlight_class->suspend = backlight_suspend;
 	backlight_class->resume = backlight_resume;
 	return 0;
 }

 /*
  * if this is compiled into the kernel, we need to ensure that the
  * class is registered before users of the class try to register lcd's
  */
 postcore_initcall(backlight_class_init);
 module_exit(backlight_class_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");
	/*
	* Backlight Lowlevel Control Abstraction
	*
	* Copyright (C) 2003,2004 Hewlett-Packard Company
	*
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/device.h>
	#include <linux/backlight.h>
	#include <linux/notifier.h>
	#include <linux/ctype.h>
	#include <linux/err.h>
	#include <linux/fb.h>
	#include <linux/slab.h>

	#ifdef CONFIG_PMAC_BACKLIGHT
	#include <asm/backlight.h>
	#endif

	static const char *const backlight_types[] = {
	[BACKLIGHT_RAW] = "raw",
	[BACKLIGHT_PLATFORM] = "platform",
	[BACKLIGHT_FIRMWARE] = "firmware",
	};

	#if defined(CONFIG_FB) \|\| (defined(CONFIG_FB_MODULE) && \
	defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
	/* This callback gets called when something important happens inside a
	* framebuffer driver. We're looking if that important event is blanking,
	* and if it is, we're switching backlight power as well ...
	*/
	static int fb_notifier_callback(struct notifier_block *self,
	unsigned long event, void *data)
	{
	struct backlight_device *bd;
	struct fb_event *evdata = data;

	/* If we aren't interested in this event, skip it immediately ... */
	if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
	return 0;

	bd = container_of(self, struct backlight_device, fb_notif);
	mutex_lock(&bd->ops_lock);
	if (bd->ops)
	if (!bd->ops->check_fb \|\|
	bd->ops->check_fb(bd, evdata->info)) {
	bd->props.fb_blank = (int )evdata->data;
	if (bd->props.fb_blank == FB_BLANK_UNBLANK)
	bd->props.state &= ~BL_CORE_FBBLANK;
	else
	bd->props.state \|= BL_CORE_FBBLANK;
	backlight_update_status(bd);
	}
	mutex_unlock(&bd->ops_lock);
	return 0;
	}

	static int backlight_register_fb(struct backlight_device *bd)
	{
	memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
	bd->fb_notif.notifier_call = fb_notifier_callback;

	return fb_register_client(&bd->fb_notif);
	}

	static void backlight_unregister_fb(struct backlight_device *bd)
	{
	fb_unregister_client(&bd->fb_notif);
	}
	#else
	static inline int backlight_register_fb(struct backlight_device *bd)
	{
	return 0;
	}

	static inline void backlight_unregister_fb(struct backlight_device *bd)
	{
	}
	#endif /* CONFIG_FB */

	static void backlight_generate_event(struct backlight_device *bd,
	enum backlight_update_reason reason)
	{
	char *envp[2];

	switch (reason) {
	case BACKLIGHT_UPDATE_SYSFS:
	envp[0] = "SOURCE=sysfs";
	break;
	case BACKLIGHT_UPDATE_HOTKEY:
	envp[0] = "SOURCE=hotkey";
	break;
	default:
	envp[0] = "SOURCE=unknown";
	break;
	}
	envp[1] = NULL;
	kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
	sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
	}

	static ssize_t backlight_show_power(struct device *dev,
	struct device_attribute attr,char buf)
	{
	struct backlight_device *bd = to_backlight_device(dev);

	return sprintf(buf, "%d\n", bd->props.power);
	}

	static ssize_t backlight_store_power(struct device *dev,
	struct device_attribute attr, const char buf, size_t count)
	{
	int rc;
	struct backlight_device *bd = to_backlight_device(dev);
	unsigned long power;

	rc = strict_strtoul(buf, 0, &power);
	if (rc)
	return rc;

	rc = -ENXIO;
	mutex_lock(&bd->ops_lock);
	if (bd->ops) {
	pr_debug("backlight: set power to %lu\n", power);
	if (bd->props.power != power) {
	bd->props.power = power;
	backlight_update_status(bd);
	}
	rc = count;
	}
	mutex_unlock(&bd->ops_lock);

	return rc;
	}

	static ssize_t backlight_show_brightness(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct backlight_device *bd = to_backlight_device(dev);

	return sprintf(buf, "%d\n", bd->props.brightness);
	}

	static ssize_t backlight_store_brightness(struct device *dev,
	struct device_attribute attr, const char buf, size_t count)
	{
	int rc;
	struct backlight_device *bd = to_backlight_device(dev);
	unsigned long brightness;

	rc = strict_strtoul(buf, 0, &brightness);
	if (rc)
	return rc;

	rc = -ENXIO;

	mutex_lock(&bd->ops_lock);
	if (bd->ops) {
	if (brightness > bd->props.max_brightness)
	rc = -EINVAL;
	else {
	pr_debug("backlight: set brightness to %lu\n",
	brightness);
	bd->props.brightness = brightness;
	backlight_update_status(bd);
	rc = count;
	}
	}
	mutex_unlock(&bd->ops_lock);

	backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);

	return rc;
	}

	static ssize_t backlight_show_type(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct backlight_device *bd = to_backlight_device(dev);

	return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
	}

	static ssize_t backlight_show_max_brightness(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct backlight_device *bd = to_backlight_device(dev);

	return sprintf(buf, "%d\n", bd->props.max_brightness);
	}

	static ssize_t backlight_show_actual_brightness(struct device *dev,
	struct device_attribute attr, char buf)
	{
	int rc = -ENXIO;
	struct backlight_device *bd = to_backlight_device(dev);

	mutex_lock(&bd->ops_lock);
	if (bd->ops && bd->ops->get_brightness)
	rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
	mutex_unlock(&bd->ops_lock);

	return rc;
	}

	static struct class *backlight_class;

	static int backlight_suspend(struct device *dev, pm_message_t state)
	{
	struct backlight_device *bd = to_backlight_device(dev);

	mutex_lock(&bd->ops_lock);
	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
	bd->props.state \|= BL_CORE_SUSPENDED;
	backlight_update_status(bd);
	}
	mutex_unlock(&bd->ops_lock);

	return 0;
	}

	static int backlight_resume(struct device *dev)
	{
	struct backlight_device *bd = to_backlight_device(dev);

	mutex_lock(&bd->ops_lock);
	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
	bd->props.state &= ~BL_CORE_SUSPENDED;
	backlight_update_status(bd);
	}
	mutex_unlock(&bd->ops_lock);

	return 0;
	}

	static void bl_device_release(struct device *dev)
	{
	struct backlight_device *bd = to_backlight_device(dev);
	kfree(bd);
	}

	static struct device_attribute bl_device_attributes[] = {
	__ATTR(bl_power, 0644, backlight_show_power, backlight_store_power),
	__ATTR(brightness, 0644, backlight_show_brightness,
	backlight_store_brightness),
	__ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
	NULL),
	__ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
	__ATTR(type, 0444, backlight_show_type, NULL),
	__ATTR_NULL,
	};

	/**
	* backlight_force_update - tell the backlight subsystem that hardware state
	* has changed
	* @bd: the backlight device to update
	*
	* Updates the internal state of the backlight in response to a hardware event,
	* and generate a uevent to notify userspace
	*/
	void backlight_force_update(struct backlight_device *bd,
	enum backlight_update_reason reason)
	{
	mutex_lock(&bd->ops_lock);
	if (bd->ops && bd->ops->get_brightness)
	bd->props.brightness = bd->ops->get_brightness(bd);
	mutex_unlock(&bd->ops_lock);
	backlight_generate_event(bd, reason);
	}
	EXPORT_SYMBOL(backlight_force_update);

	/**
	* backlight_device_register - create and register a new object of
	* backlight_device class.
	* @name: the name of the new object(must be the same as the name of the
	* respective framebuffer device).
	* @parent: a pointer to the parent device
	* @devdata: an optional pointer to be stored for private driver use. The
	* methods may retrieve it by using bl_get_data(bd).
	* @ops: the backlight operations structure.
	*
	* Creates and registers new backlight device. Returns either an
	* ERR_PTR() or a pointer to the newly allocated device.
	*/
	struct backlight_device backlight_device_register(const char name,
	struct device parent, void devdata, const struct backlight_ops *ops,
	const struct backlight_properties *props)
	{
	struct backlight_device *new_bd;
	int rc;

	pr_debug("backlight_device_register: name=%s\n", name);

	new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
	if (!new_bd)
	return ERR_PTR(-ENOMEM);

	mutex_init(&new_bd->update_lock);
	mutex_init(&new_bd->ops_lock);

	new_bd->dev.class = backlight_class;
	new_bd->dev.parent = parent;
	new_bd->dev.release = bl_device_release;
	dev_set_name(&new_bd->dev, name);
	dev_set_drvdata(&new_bd->dev, devdata);

	/* Set default properties */
	if (props) {
	memcpy(&new_bd->props, props,
	sizeof(struct backlight_properties));
	if (props->type <= 0 \|\| props->type >= BACKLIGHT_TYPE_MAX) {
	WARN(1, "%s: invalid backlight type", name);
	new_bd->props.type = BACKLIGHT_RAW;
	}
	} else {
	new_bd->props.type = BACKLIGHT_RAW;
	}

	rc = device_register(&new_bd->dev);
	if (rc) {
	kfree(new_bd);
	return ERR_PTR(rc);
	}

	rc = backlight_register_fb(new_bd);
	if (rc) {
	device_unregister(&new_bd->dev);
	return ERR_PTR(rc);
	}

	new_bd->ops = ops;

	#ifdef CONFIG_PMAC_BACKLIGHT
	mutex_lock(&pmac_backlight_mutex);
	if (!pmac_backlight)
	pmac_backlight = new_bd;
	mutex_unlock(&pmac_backlight_mutex);
	#endif

	return new_bd;
	}
	EXPORT_SYMBOL(backlight_device_register);

	/**
	* backlight_device_unregister - unregisters a backlight device object.
	* @bd: the backlight device object to be unregistered and freed.
	*
	* Unregisters a previously registered via backlight_device_register object.
	*/
	void backlight_device_unregister(struct backlight_device *bd)
	{
	if (!bd)
	return;

	#ifdef CONFIG_PMAC_BACKLIGHT
	mutex_lock(&pmac_backlight_mutex);
	if (pmac_backlight == bd)
	pmac_backlight = NULL;
	mutex_unlock(&pmac_backlight_mutex);
	#endif
	mutex_lock(&bd->ops_lock);
	bd->ops = NULL;
	mutex_unlock(&bd->ops_lock);

	backlight_unregister_fb(bd);
	device_unregister(&bd->dev);
	}
	EXPORT_SYMBOL(backlight_device_unregister);

	static void __exit backlight_class_exit(void)
	{
	class_destroy(backlight_class);
	}

	static int __init backlight_class_init(void)
	{
	backlight_class = class_create(THIS_MODULE, "backlight");
	if (IS_ERR(backlight_class)) {
	printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
	PTR_ERR(backlight_class));
	return PTR_ERR(backlight_class);
	}

	backlight_class->dev_attrs = bl_device_attributes;
	backlight_class->suspend = backlight_suspend;
	backlight_class->resume = backlight_resume;
	return 0;
	}

	/*
	* if this is compiled into the kernel, we need to ensure that the
	* class is registered before users of the class try to register lcd's
	*/
	postcore_initcall(backlight_class_init);
	module_exit(backlight_class_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
	MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");