Linux LED 子系统

设备树

设备树属性

属性	描述	备注
gpios	指定 LED 的 GPIO，参考 gpios property
function		可选
color		可选
label		可选
linux,default-trigger		可选
default-state		可选
retain-state-suspended		可选
retain-state-shutdown		可选
panic-indicator		可选

设备命名

遵循 devicename:color:function 格式，其中：

• devicename
• color
• function

正确的 LED 命名示例：

"red:disk"
"white:flash"
"red:indicator"
"phy1:green:wlan"
"phy3::wlan"
":kbd_backlight"
"input5::kbd_backlight"
"input3::numlock"
"input3::scrolllock"
"input3::capslock"
"mmc1::status"
"white:status"

LED 功能

定义在 include/dt-bindings/leds/common.h

/* Standard LED functions */
#define LED_FUNCTION_ACTIVITY "activity"
#define LED_FUNCTION_ALARM "alarm"
#define LED_FUNCTION_BACKLIGHT "backlight"
#define LED_FUNCTION_BLUETOOTH "bluetooth"
#define LED_FUNCTION_BOOT "boot"
#define LED_FUNCTION_CPU "cpu"
#define LED_FUNCTION_CAPSLOCK "capslock"
#define LED_FUNCTION_CHARGING "charging"
#define LED_FUNCTION_DEBUG "debug"
#define LED_FUNCTION_DISK "disk"
#define LED_FUNCTION_DISK_ACTIVITY "disk-activity"
#define LED_FUNCTION_DISK_ERR "disk-err"
#define LED_FUNCTION_DISK_READ "disk-read"
#define LED_FUNCTION_DISK_WRITE "disk-write"
#define LED_FUNCTION_FAULT "fault"
#define LED_FUNCTION_FLASH "flash"
#define LED_FUNCTION_HEARTBEAT "heartbeat"
#define LED_FUNCTION_INDICATOR "indicator"
#define LED_FUNCTION_KBD_BACKLIGHT "kbd_backlight"
#define LED_FUNCTION_LAN "lan"
#define LED_FUNCTION_MAIL "mail"
#define LED_FUNCTION_MTD "mtd"
#define LED_FUNCTION_MICMUTE "micmute"
#define LED_FUNCTION_MUTE "mute"
#define LED_FUNCTION_NUMLOCK "numlock"
#define LED_FUNCTION_PANIC "panic"
#define LED_FUNCTION_PROGRAMMING "programming"
#define LED_FUNCTION_POWER "power"
#define LED_FUNCTION_RX "rx"
#define LED_FUNCTION_SD "sd"
#define LED_FUNCTION_SCROLLLOCK "scrolllock"
#define LED_FUNCTION_STANDBY "standby"
#define LED_FUNCTION_STATUS "status"
#define LED_FUNCTION_TORCH "torch"
#define LED_FUNCTION_TX "tx"
#define LED_FUNCTION_USB "usb"
#define LED_FUNCTION_WAN "wan"
#define LED_FUNCTION_WLAN "wlan"
#define LED_FUNCTION_WPS "wps"

示例

#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/leds/common.h>

leds {
	compatible = "gpio-leds";
	led0 {
		gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
		linux,default-trigger = "disk-activity";
		function = LED_FUNCTION_DISK;
	};

	led1 {
		gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
		/* Keep LED on if BIOS detected hardware fault */
		default-state = "keep";
		function = LED_FUNCTION_FAULT;
	};
};

run-control {
	compatible = "gpio-leds";
	led0 {
		gpios = <&mpc8572 6 GPIO_ACTIVE_HIGH>;
		color = <LED_COLOR_ID_RED>;
		default-state = "off";
	};
	led1 {
		gpios = <&mpc8572 7 GPIO_ACTIVE_HIGH>;
		color = <LED_COLOR_ID_GREEN>;
		default-state = "on";
	};
};

leds {
	compatible = "gpio-leds";

	led0 {
		gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>;
		linux,default-trigger = "max8903-charger-charging";
		retain-state-suspended;
		function = LED_FUNCTION_CHARGE;
	};
};