LED

Introduction

LEDs can be controlled by using the LED device subsystem or by
directly operating GPIO.

Controlling LEDs by device

Linux has its own LED subsystem for LED devices. In AIO-1126BJD4V0,
LEDs are configured as LED class devices.You can control them via
"/sys/class/leds/".

You can change the behavior of each LED by using the echo command to
write command to its brightness property:

上层灯：

   echo 1 > /sys/class/leds/\:user/brightness #Upper lights on
   echo 0 > /sys/class/leds/\:user/brightness #Upper lights off

下层灯：

   echo 1 > /sys/class/leds/\:power/brightness #Lower level lights on
   echo 0 > /sys/class/leds/\:power/brightness #Lower level lights off

Using trigger control LED

Trigger contains a variety of ways to control the LED, here with two
examples to illustrate.

Simple trigger LED

Complex trigger LED

For more information, please read the document "leds-class.txt".

First of all, we need to know how many LED definition, while the
corresponding property of the LED is.

The board-level configuration is located in
"sdk/kernel-6.1/arch/arm64/boot/dts/rockchip/rv1126b-firefly-aio-
1126bjd4v0.dtsi"：

   leds: leds {
           compatible = "gpio-leds";

           work {
                   label = ":power";
                   linux,default-trigger = "ir-power-click";
                   gpios = <&gpio0 RK_PA6 GPIO_ACTIVE_HIGH>;
                   pinctrl-names = "default";
                   pinctrl-0 = <&led_power>;
                   default-state = "on";
           };

           user {
                   label = ":user";
                   linux,default-trigger = "ir-user-click";
                   gpios = <&gpio0 RK_PC5 GPIO_ACTIVE_HIGH>;
                   pinctrl-names = "default";
                   pinctrl-0 = <&led_user>;
                   default-state = "off";
           };
   };

Note: The value of "compatible" must match the one in "drivers/leds
/leds-gpio.c".

Complex trigger LED

The following is the trigger mode control LED complex example, "timer
trigger" is to let the LED to achieve constant light off effect.

We need to configure the timer trigger on the kernel.

In the "kernel" path using "make menuconfig", in accordance with the
following method to chose "timer trigger" driver.

   Device Drivers
   --->LED Support
      --->LED Trigger support
         --->LED Timer Trigger

Save the configuration and compile the kernel, the "kernel.img" burn
AIO-1126BJD4V0 board. We can use the serial input command, you can see
the blue light non-stop interval flashing.

   echo "timer" > /sys/class/leds/:user/trigger

The user can also use the "cat" command to get the available values
for the trigger:

   # cat /sys/class/leds/:user/trigger
   none ir-power-click rfkill-any rfkill-none test_ac-online test_battery-charging-or-full 
   test_battery-charging test_battery-full test_battery-charging-blink-full-solid 
   test_usb-online mmc0 [timer] heartbeat backlight default-on ir-user-click mmc1 
   rfkill0 tcpm-source-psy-6-0022-online rfkill1 rfkill2