| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Backlight Lowlevel Control Abstraction |
| * |
| * Copyright (C) 2003,2004 Hewlett-Packard Company |
| * |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #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 |
| |
| /** |
| * DOC: overview |
| * |
| * The backlight core supports implementing backlight drivers. |
| * |
| * A backlight driver registers a driver using |
| * devm_backlight_device_register(). The properties of the backlight |
| * driver such as type and max_brightness must be specified. |
| * When the core detect changes in for example brightness or power state |
| * the update_status() operation is called. The backlight driver shall |
| * implement this operation and use it to adjust backlight. |
| * |
| * Several sysfs attributes are provided by the backlight core:: |
| * |
| * - brightness R/W, set the requested brightness level |
| * - actual_brightness RO, the brightness level used by the HW |
| * - max_brightness RO, the maximum brightness level supported |
| * |
| * See Documentation/ABI/stable/sysfs-class-backlight for the full list. |
| * |
| * The backlight can be adjusted using the sysfs interface, and |
| * the backlight driver may also support adjusting backlight using |
| * a hot-key or some other platform or firmware specific way. |
| * |
| * The driver must implement the get_brightness() operation if |
| * the HW do not support all the levels that can be specified in |
| * brightness, thus providing user-space access to the actual level |
| * via the actual_brightness attribute. |
| * |
| * When the backlight changes this is reported to user-space using |
| * an uevent connected to the actual_brightness attribute. |
| * When brightness is set by platform specific means, for example |
| * a hot-key to adjust backlight, the driver must notify the backlight |
| * core that brightness has changed using backlight_force_update(). |
| * |
| * The backlight driver core receives notifications from fbdev and |
| * if the event is FB_EVENT_BLANK and if the value of blank, from the |
| * FBIOBLANK ioctrl, results in a change in the backlight state the |
| * update_status() operation is called. |
| */ |
| |
| static struct list_head backlight_dev_list; |
| static struct mutex backlight_dev_list_mutex; |
| static struct blocking_notifier_head backlight_notifier; |
| |
| static const char *const backlight_types[] = { |
| [BACKLIGHT_RAW] = "raw", |
| [BACKLIGHT_PLATFORM] = "platform", |
| [BACKLIGHT_FIRMWARE] = "firmware", |
| }; |
| |
| static const char *const backlight_scale_types[] = { |
| [BACKLIGHT_SCALE_UNKNOWN] = "unknown", |
| [BACKLIGHT_SCALE_LINEAR] = "linear", |
| [BACKLIGHT_SCALE_NON_LINEAR] = "non-linear", |
| }; |
| |
| #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \ |
| defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)) |
| /* |
| * fb_notifier_callback |
| * |
| * This callback gets called when something important happens inside a |
| * framebuffer driver. The backlight core only cares about FB_BLANK_UNBLANK |
| * which is reported to the driver using backlight_update_status() |
| * as a state change. |
| * |
| * There may be several fbdev's connected to the backlight device, |
| * in which case they are kept track of. A state change is only reported |
| * if there is a change in backlight for the specified fbdev. |
| */ |
| static int fb_notifier_callback(struct notifier_block *self, |
| unsigned long event, void *data) |
| { |
| struct backlight_device *bd; |
| struct fb_event *evdata = data; |
| int node = evdata->info->node; |
| int fb_blank = 0; |
| |
| /* If we aren't interested in this event, skip it immediately ... */ |
| if (event != FB_EVENT_BLANK) |
| return 0; |
| |
| bd = container_of(self, struct backlight_device, fb_notif); |
| mutex_lock(&bd->ops_lock); |
| |
| if (!bd->ops) |
| goto out; |
| if (bd->ops->check_fb && !bd->ops->check_fb(bd, evdata->info)) |
| goto out; |
| |
| fb_blank = *(int *)evdata->data; |
| if (fb_blank == FB_BLANK_UNBLANK && !bd->fb_bl_on[node]) { |
| bd->fb_bl_on[node] = true; |
| if (!bd->use_count++) { |
| bd->props.state &= ~BL_CORE_FBBLANK; |
| bd->props.fb_blank = FB_BLANK_UNBLANK; |
| backlight_update_status(bd); |
| } |
| } else if (fb_blank != FB_BLANK_UNBLANK && bd->fb_bl_on[node]) { |
| bd->fb_bl_on[node] = false; |
| if (!(--bd->use_count)) { |
| bd->props.state |= BL_CORE_FBBLANK; |
| bd->props.fb_blank = fb_blank; |
| backlight_update_status(bd); |
| } |
| } |
| out: |
| 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 bl_power_show(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 bl_power_store(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, old_power; |
| |
| rc = kstrtoul(buf, 0, &power); |
| if (rc) |
| return rc; |
| |
| rc = -ENXIO; |
| mutex_lock(&bd->ops_lock); |
| if (bd->ops) { |
| pr_debug("set power to %lu\n", power); |
| if (bd->props.power != power) { |
| old_power = bd->props.power; |
| bd->props.power = power; |
| rc = backlight_update_status(bd); |
| if (rc) |
| bd->props.power = old_power; |
| else |
| rc = count; |
| } else { |
| rc = count; |
| } |
| } |
| mutex_unlock(&bd->ops_lock); |
| |
| return rc; |
| } |
| static DEVICE_ATTR_RW(bl_power); |
| |
| static ssize_t brightness_show(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); |
| } |
| |
| int backlight_device_set_brightness(struct backlight_device *bd, |
| unsigned long brightness) |
| { |
| int rc = -ENXIO; |
| |
| mutex_lock(&bd->ops_lock); |
| if (bd->ops) { |
| if (brightness > bd->props.max_brightness) |
| rc = -EINVAL; |
| else { |
| pr_debug("set brightness to %lu\n", brightness); |
| bd->props.brightness = brightness; |
| rc = backlight_update_status(bd); |
| } |
| } |
| mutex_unlock(&bd->ops_lock); |
| |
| backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS); |
| |
| return rc; |
| } |
| EXPORT_SYMBOL(backlight_device_set_brightness); |
| |
| static ssize_t brightness_store(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 = kstrtoul(buf, 0, &brightness); |
| if (rc) |
| return rc; |
| |
| rc = backlight_device_set_brightness(bd, brightness); |
| |
| return rc ? rc : count; |
| } |
| static DEVICE_ATTR_RW(brightness); |
| |
| static ssize_t type_show(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 DEVICE_ATTR_RO(type); |
| |
| static ssize_t max_brightness_show(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 DEVICE_ATTR_RO(max_brightness); |
| |
| static ssize_t actual_brightness_show(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 = bd->ops->get_brightness(bd); |
| if (rc >= 0) |
| rc = sprintf(buf, "%d\n", rc); |
| } else { |
| rc = sprintf(buf, "%d\n", bd->props.brightness); |
| } |
| mutex_unlock(&bd->ops_lock); |
| |
| return rc; |
| } |
| static DEVICE_ATTR_RO(actual_brightness); |
| |
| static ssize_t scale_show(struct device *dev, |
| struct device_attribute *attr, char *buf) |
| { |
| struct backlight_device *bd = to_backlight_device(dev); |
| |
| if (WARN_ON(bd->props.scale > BACKLIGHT_SCALE_NON_LINEAR)) |
| return sprintf(buf, "unknown\n"); |
| |
| return sprintf(buf, "%s\n", backlight_scale_types[bd->props.scale]); |
| } |
| static DEVICE_ATTR_RO(scale); |
| |
| static struct class *backlight_class; |
| |
| #ifdef CONFIG_PM_SLEEP |
| static int backlight_suspend(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 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; |
| } |
| #endif |
| |
| static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend, |
| backlight_resume); |
| |
| static void bl_device_release(struct device *dev) |
| { |
| struct backlight_device *bd = to_backlight_device(dev); |
| kfree(bd); |
| } |
| |
| static struct attribute *bl_device_attrs[] = { |
| &dev_attr_bl_power.attr, |
| &dev_attr_brightness.attr, |
| &dev_attr_actual_brightness.attr, |
| &dev_attr_max_brightness.attr, |
| &dev_attr_scale.attr, |
| &dev_attr_type.attr, |
| NULL, |
| }; |
| ATTRIBUTE_GROUPS(bl_device); |
| |
| /** |
| * backlight_force_update - tell the backlight subsystem that hardware state |
| * has changed |
| * @bd: the backlight device to update |
| * @reason: reason for update |
| * |
| * Updates the internal state of the backlight in response to a hardware event, |
| * and generates an uevent to notify userspace. A backlight driver shall call |
| * backlight_force_update() when the backlight is changed using, for example, |
| * a hot-key. The updated brightness is read using get_brightness() and the |
| * brightness value is reported using an uevent. |
| */ |
| void backlight_force_update(struct backlight_device *bd, |
| enum backlight_update_reason reason) |
| { |
| int brightness; |
| |
| mutex_lock(&bd->ops_lock); |
| if (bd->ops && bd->ops->get_brightness) { |
| brightness = bd->ops->get_brightness(bd); |
| if (brightness >= 0) |
| bd->props.brightness = brightness; |
| else |
| dev_err(&bd->dev, |
| "Could not update brightness from device: %pe\n", |
| ERR_PTR(brightness)); |
| } |
| mutex_unlock(&bd->ops_lock); |
| backlight_generate_event(bd, reason); |
| } |
| EXPORT_SYMBOL(backlight_force_update); |
| |
| /* deprecated - use devm_backlight_device_register() */ |
| 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, "%s", 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) { |
| put_device(&new_bd->dev); |
| 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 |
| |
| mutex_lock(&backlight_dev_list_mutex); |
| list_add(&new_bd->entry, &backlight_dev_list); |
| mutex_unlock(&backlight_dev_list_mutex); |
| |
| blocking_notifier_call_chain(&backlight_notifier, |
| BACKLIGHT_REGISTERED, new_bd); |
| |
| return new_bd; |
| } |
| EXPORT_SYMBOL(backlight_device_register); |
| |
| /** backlight_device_get_by_type - find first backlight device of a type |
| * @type: the type of backlight device |
| * |
| * Look up the first backlight device of the specified type |
| * |
| * RETURNS: |
| * |
| * Pointer to backlight device if any was found. Otherwise NULL. |
| */ |
| struct backlight_device *backlight_device_get_by_type(enum backlight_type type) |
| { |
| bool found = false; |
| struct backlight_device *bd; |
| |
| mutex_lock(&backlight_dev_list_mutex); |
| list_for_each_entry(bd, &backlight_dev_list, entry) { |
| if (bd->props.type == type) { |
| found = true; |
| break; |
| } |
| } |
| mutex_unlock(&backlight_dev_list_mutex); |
| |
| return found ? bd : NULL; |
| } |
| EXPORT_SYMBOL(backlight_device_get_by_type); |
| |
| /** |
| * backlight_device_get_by_name - Get backlight device by name |
| * @name: Device name |
| * |
| * This function looks up a backlight device by its name. It obtains a reference |
| * on the backlight device and it is the caller's responsibility to drop the |
| * reference by calling put_device(). |
| * |
| * Returns: |
| * A pointer to the backlight device if found, otherwise NULL. |
| */ |
| struct backlight_device *backlight_device_get_by_name(const char *name) |
| { |
| struct device *dev; |
| |
| dev = class_find_device_by_name(backlight_class, name); |
| |
| return dev ? to_backlight_device(dev) : NULL; |
| } |
| EXPORT_SYMBOL(backlight_device_get_by_name); |
| |
| /* deprecated - use devm_backlight_device_unregister() */ |
| void backlight_device_unregister(struct backlight_device *bd) |
| { |
| if (!bd) |
| return; |
| |
| mutex_lock(&backlight_dev_list_mutex); |
| list_del(&bd->entry); |
| mutex_unlock(&backlight_dev_list_mutex); |
| |
| #ifdef CONFIG_PMAC_BACKLIGHT |
| mutex_lock(&pmac_backlight_mutex); |
| if (pmac_backlight == bd) |
| pmac_backlight = NULL; |
| mutex_unlock(&pmac_backlight_mutex); |
| #endif |
| |
| blocking_notifier_call_chain(&backlight_notifier, |
| BACKLIGHT_UNREGISTERED, bd); |
| |
| 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 devm_backlight_device_release(struct device *dev, void *res) |
| { |
| struct backlight_device *backlight = *(struct backlight_device **)res; |
| |
| backlight_device_unregister(backlight); |
| } |
| |
| static int devm_backlight_device_match(struct device *dev, void *res, |
| void *data) |
| { |
| struct backlight_device **r = res; |
| |
| return *r == data; |
| } |
| |
| /** |
| * backlight_register_notifier - get notified of backlight (un)registration |
| * @nb: notifier block with the notifier to call on backlight (un)registration |
| * |
| * Register a notifier to get notified when backlight devices get registered |
| * or unregistered. |
| * |
| * RETURNS: |
| * |
| * 0 on success, otherwise a negative error code |
| */ |
| int backlight_register_notifier(struct notifier_block *nb) |
| { |
| return blocking_notifier_chain_register(&backlight_notifier, nb); |
| } |
| EXPORT_SYMBOL(backlight_register_notifier); |
| |
| /** |
| * backlight_unregister_notifier - unregister a backlight notifier |
| * @nb: notifier block to unregister |
| * |
| * Register a notifier to get notified when backlight devices get registered |
| * or unregistered. |
| * |
| * RETURNS: |
| * |
| * 0 on success, otherwise a negative error code |
| */ |
| int backlight_unregister_notifier(struct notifier_block *nb) |
| { |
| return blocking_notifier_chain_unregister(&backlight_notifier, nb); |
| } |
| EXPORT_SYMBOL(backlight_unregister_notifier); |
| |
| /** |
| * devm_backlight_device_register - register a new backlight device |
| * @dev: the device to register |
| * @name: the name of the device |
| * @parent: a pointer to the parent device (often the same as @dev) |
| * @devdata: an optional pointer to be stored for private driver use |
| * @ops: the backlight operations structure |
| * @props: the backlight properties |
| * |
| * Creates and registers new backlight device. When a backlight device |
| * is registered the configuration must be specified in the @props |
| * parameter. See description of &backlight_properties. |
| * |
| * RETURNS: |
| * |
| * struct backlight on success, or an ERR_PTR on error |
| */ |
| struct backlight_device *devm_backlight_device_register(struct device *dev, |
| const char *name, struct device *parent, void *devdata, |
| const struct backlight_ops *ops, |
| const struct backlight_properties *props) |
| { |
| struct backlight_device **ptr, *backlight; |
| |
| ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr), |
| GFP_KERNEL); |
| if (!ptr) |
| return ERR_PTR(-ENOMEM); |
| |
| backlight = backlight_device_register(name, parent, devdata, ops, |
| props); |
| if (!IS_ERR(backlight)) { |
| *ptr = backlight; |
| devres_add(dev, ptr); |
| } else { |
| devres_free(ptr); |
| } |
| |
| return backlight; |
| } |
| EXPORT_SYMBOL(devm_backlight_device_register); |
| |
| /** |
| * devm_backlight_device_unregister - unregister backlight device |
| * @dev: the device to unregister |
| * @bd: the backlight device to unregister |
| * |
| * Deallocates a backlight allocated with devm_backlight_device_register(). |
| * Normally this function will not need to be called and the resource management |
| * code will ensure that the resources are freed. |
| */ |
| void devm_backlight_device_unregister(struct device *dev, |
| struct backlight_device *bd) |
| { |
| int rc; |
| |
| rc = devres_release(dev, devm_backlight_device_release, |
| devm_backlight_device_match, bd); |
| WARN_ON(rc); |
| } |
| EXPORT_SYMBOL(devm_backlight_device_unregister); |
| |
| #ifdef CONFIG_OF |
| static int of_parent_match(struct device *dev, const void *data) |
| { |
| return dev->parent && dev->parent->of_node == data; |
| } |
| |
| /** |
| * of_find_backlight_by_node() - find backlight device by device-tree node |
| * @node: device-tree node of the backlight device |
| * |
| * Returns a pointer to the backlight device corresponding to the given DT |
| * node or NULL if no such backlight device exists or if the device hasn't |
| * been probed yet. |
| * |
| * This function obtains a reference on the backlight device and it is the |
| * caller's responsibility to drop the reference by calling put_device() on |
| * the backlight device's .dev field. |
| */ |
| struct backlight_device *of_find_backlight_by_node(struct device_node *node) |
| { |
| struct device *dev; |
| |
| dev = class_find_device(backlight_class, NULL, node, of_parent_match); |
| |
| return dev ? to_backlight_device(dev) : NULL; |
| } |
| EXPORT_SYMBOL(of_find_backlight_by_node); |
| #endif |
| |
| static struct backlight_device *of_find_backlight(struct device *dev) |
| { |
| struct backlight_device *bd = NULL; |
| struct device_node *np; |
| |
| if (!dev) |
| return NULL; |
| |
| if (IS_ENABLED(CONFIG_OF) && dev->of_node) { |
| np = of_parse_phandle(dev->of_node, "backlight", 0); |
| if (np) { |
| bd = of_find_backlight_by_node(np); |
| of_node_put(np); |
| if (!bd) |
| return ERR_PTR(-EPROBE_DEFER); |
| } |
| } |
| |
| return bd; |
| } |
| |
| static void devm_backlight_release(void *data) |
| { |
| struct backlight_device *bd = data; |
| |
| put_device(&bd->dev); |
| } |
| |
| /** |
| * devm_of_find_backlight - find backlight for a device |
| * @dev: the device |
| * |
| * This function looks for a property named 'backlight' on the DT node |
| * connected to @dev and looks up the backlight device. The lookup is |
| * device managed so the reference to the backlight device is automatically |
| * dropped on driver detach. |
| * |
| * RETURNS: |
| * |
| * A pointer to the backlight device if found. |
| * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight |
| * device is found. NULL if there's no backlight property. |
| */ |
| struct backlight_device *devm_of_find_backlight(struct device *dev) |
| { |
| struct backlight_device *bd; |
| int ret; |
| |
| bd = of_find_backlight(dev); |
| if (IS_ERR_OR_NULL(bd)) |
| return bd; |
| ret = devm_add_action_or_reset(dev, devm_backlight_release, bd); |
| if (ret) |
| return ERR_PTR(ret); |
| |
| return bd; |
| } |
| EXPORT_SYMBOL(devm_of_find_backlight); |
| |
| static void __exit backlight_class_exit(void) |
| { |
| class_destroy(backlight_class); |
| } |
| |
| static int __init backlight_class_init(void) |
| { |
| backlight_class = class_create("backlight"); |
| if (IS_ERR(backlight_class)) { |
| pr_warn("Unable to create backlight class; errno = %ld\n", |
| PTR_ERR(backlight_class)); |
| return PTR_ERR(backlight_class); |
| } |
| |
| backlight_class->dev_groups = bl_device_groups; |
| backlight_class->pm = &backlight_class_dev_pm_ops; |
| INIT_LIST_HEAD(&backlight_dev_list); |
| mutex_init(&backlight_dev_list_mutex); |
| BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier); |
| |
| 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"); |