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backlight: Add backlight_device_get_by_name()

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Add a way to lookup a backlight device based on its name.
Will be used by a USB display gadget getting the name from configfs.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Noralf Trønnes 2020-05-09 16:16:10 +02:00 committed by Lee Jones
parent 62a1d3f623
commit 479da1f538
2 changed files with 22 additions and 0 deletions
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21
drivers/video/backlight/backlight.c
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@ -432,6 +432,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
}
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 backlight_put().
*
* 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);
/**
* backlight_device_unregister - unregisters a backlight device object.
* @bd: the backlight device object to be unregistered and freed.

1
include/linux/backlight.h
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@ -190,6 +190,7 @@ extern void backlight_force_update(struct backlight_device *bd,
extern int backlight_register_notifier(struct notifier_block *nb);
extern int backlight_unregister_notifier(struct notifier_block *nb);
extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
struct backlight_device *backlight_device_get_by_name(const char *name);
extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)