base-files: add option to set LED brightness

Add option to set LED brightness via uci:

config led 'led_blue'
        option name 'blue'
        option sysfs 'blue:status'
        option brightness '1'

Signed-off-by: Paweł Owoc <[email protected]>

Link: https://github.com/openwrt/openwrt/pull/17190
Signed-off-by: John Crispin <[email protected]>

package/base-files/files/etc/init.d/led

@@ -51,6 +51,7 @@ load_led() {
 	local delayon
 	local delayoff
 	local interval
+	local brightness
 
 	config_get sysfs $1 sysfs
 	config_get name $1 name "$sysfs"
@@ -67,6 +68,7 @@ load_led() {
 	config_get message $1 message ""
 	config_get gpio $1 gpio "0"
 	config_get_bool inverted $1 inverted "0"
+	config_get brightness $1 brightness
 
 	[ "$2" ] && [ "$sysfs" != "$2" ] && return
 
@@ -105,7 +107,8 @@ load_led() {
 			echo 0 >/sys/class/leds/${sysfs}/brightness
 
 		[ $default = 1 ] &&
-			cat /sys/class/leds/${sysfs}/max_brightness > /sys/class/leds/${sysfs}/brightness
+			[ -z "$brightness" ] && brightness=$(cat /sys/class/leds/${sysfs}/max_brightness)
+			echo $brightness > /sys/class/leds/${sysfs}/brightness
 
 		led_color_set "$1" "$sysfs"