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backlight: Add a display name to the core, and a function to set it

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The naming of backlight devices is not terribly useful for
associating a backlight controller with a display (assuming
it is attached to one).

Add a sysfs node that will return a display name that can be set
by other subsystems.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
This commit is contained in:
Dave Stevenson
2024-05-17 17:35:25 +01:00
committed by Phil Elwell
parent a59df153f4
commit 1e0dc5254a
2 changed files with 36 additions and 0 deletions
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21
drivers/video/backlight/backlight.c
View File

@@ -285,6 +285,15 @@ static ssize_t max_brightness_show(struct device *dev,
}
static DEVICE_ATTR_RO(max_brightness);
static ssize_t display_name_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct backlight_device *bd = to_backlight_device(dev);
return sprintf(buf, "%s\n", bd->props.display_name);
}
static DEVICE_ATTR_RO(display_name);
static ssize_t actual_brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -365,6 +374,7 @@ static struct attribute *bl_device_attrs[] = {
&dev_attr_max_brightness.attr,
&dev_attr_scale.attr,
&dev_attr_type.attr,
&dev_attr_display_name.attr,
NULL,
};
ATTRIBUTE_GROUPS(bl_device);
@@ -662,6 +672,17 @@ static int of_parent_match(struct device *dev, const void *data)
return dev->parent && dev->parent->of_node == data;
}
int backlight_set_display_name(struct backlight_device *bd, const char *name)
{
if (!bd)
return -EINVAL;
strscpy_pad(bd->props.display_name, name, sizeof(bd->props.display_name));
return 0;
}
EXPORT_SYMBOL(backlight_set_display_name);
/**
* of_find_backlight_by_node() - find backlight device by device-tree node
* @node: device-tree node of the backlight device

15
include/linux/backlight.h
View File

@@ -270,6 +270,13 @@ struct backlight_properties {
* @scale: The type of the brightness scale.
*/
enum backlight_scale scale;
#define BL_DISPLAY_NAME_LEN 32
/**
* @display_name: Optional name that can be registered to associate a
* backlight device with a display device.
*/
char display_name[BL_DISPLAY_NAME_LEN];
};
/**
@@ -478,12 +485,20 @@ of_find_backlight_by_node(struct device_node *node)
#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
struct backlight_device *devm_of_find_backlight(struct device *dev);
int backlight_set_display_name(struct backlight_device *bd, const char *name);
#else
static inline struct backlight_device *
devm_of_find_backlight(struct device *dev)
{
return NULL;
}
static inline int backlight_set_display_name(struct backlight_device *bd,
const char *name)
{
return 0;
}
#endif
#endif