forked from Minki/linux
backlight: introduce backlight_device_registered
Introduce a new API for modules to query if a specific type of backlight device has been registered. This is useful for some backlight device provider module (e.g. ACPI video) to know if a native control interface(e.g. the interface created by i915) is available and then do things accordingly (e.g. avoid registering its own on Win8 systems). Signed-off-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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068aab7766
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@ -21,6 +21,9 @@
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#include <asm/backlight.h>
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#endif
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static struct list_head backlight_dev_list;
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static struct mutex backlight_dev_list_mutex;
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static const char *const backlight_types[] = {
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[BACKLIGHT_RAW] = "raw",
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[BACKLIGHT_PLATFORM] = "platform",
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@ -349,10 +352,32 @@ struct backlight_device *backlight_device_register(const char *name,
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mutex_unlock(&pmac_backlight_mutex);
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#endif
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mutex_lock(&backlight_dev_list_mutex);
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list_add(&new_bd->entry, &backlight_dev_list);
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mutex_unlock(&backlight_dev_list_mutex);
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return new_bd;
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}
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EXPORT_SYMBOL(backlight_device_register);
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bool backlight_device_registered(enum backlight_type type)
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{
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bool found = false;
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struct backlight_device *bd;
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mutex_lock(&backlight_dev_list_mutex);
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list_for_each_entry(bd, &backlight_dev_list, entry) {
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if (bd->props.type == type) {
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found = true;
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break;
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}
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}
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mutex_unlock(&backlight_dev_list_mutex);
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return found;
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}
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EXPORT_SYMBOL(backlight_device_registered);
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/**
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* backlight_device_unregister - unregisters a backlight device object.
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* @bd: the backlight device object to be unregistered and freed.
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@ -364,6 +389,10 @@ void backlight_device_unregister(struct backlight_device *bd)
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if (!bd)
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return;
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mutex_lock(&backlight_dev_list_mutex);
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list_del(&bd->entry);
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mutex_unlock(&backlight_dev_list_mutex);
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#ifdef CONFIG_PMAC_BACKLIGHT
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mutex_lock(&pmac_backlight_mutex);
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if (pmac_backlight == bd)
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@ -499,6 +528,8 @@ static int __init backlight_class_init(void)
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backlight_class->dev_groups = bl_device_groups;
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backlight_class->pm = &backlight_class_dev_pm_ops;
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INIT_LIST_HEAD(&backlight_dev_list);
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mutex_init(&backlight_dev_list_mutex);
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return 0;
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}
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@ -100,6 +100,9 @@ struct backlight_device {
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/* The framebuffer notifier block */
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struct notifier_block fb_notif;
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/* list entry of all registered backlight devices */
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struct list_head entry;
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struct device dev;
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};
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@ -123,6 +126,7 @@ extern void devm_backlight_device_unregister(struct device *dev,
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struct backlight_device *bd);
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extern void backlight_force_update(struct backlight_device *bd,
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enum backlight_update_reason reason);
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extern bool backlight_device_registered(enum backlight_type type);
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#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
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