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backlight: add of_find_backlight_by_node() 

This function finds the struct backlight_device for a given device tree
node.  A dummy function is provided so that it safely compiles out if OF
support is disabled.

[akpm@linux-foundation.org: Don't use IS_ENABLED(CONFIG_OF)]
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Thierry Reding <thierry.reding@avionic-design.de>
Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thierry Reding 2012-12-17 16:01:06 -08:00 committed by Linus Torvalds
parent fb08cd9b11
commit 762a936fba
2 changed files with 39 additions and 0 deletions
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29
drivers/video/backlight/backlight.c
View File

@ -370,6 +370,35 @@ void backlight_device_unregister(struct backlight_device *bd)
} }
EXPORT_SYMBOL(backlight_device_unregister); EXPORT_SYMBOL(backlight_device_unregister);
#ifdef CONFIG_OF
static int of_parent_match(struct device *dev, 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 void __exit backlight_class_exit(void) static void __exit backlight_class_exit(void)
{ {
class_destroy(backlight_class); class_destroy(backlight_class);

10
include/linux/backlight.h
View File

@ -134,4 +134,14 @@ struct generic_bl_info {
void (*kick_battery)(void); void (*kick_battery)(void);
}; };
#ifdef CONFIG_OF
struct backlight_device *of_find_backlight_by_node(struct device_node *node);
#else
static inline struct backlight_device *
of_find_backlight_by_node(struct device_node *node)
{
return NULL;
}
#endif
#endif #endif