查看原理图
查看原理图，根据引脚分配表，找到led的gpio控制引脚。
led子系统
LED驱动可以直接采用gpio子系统或led子系统两种方式控制。此处采用led子系统，要确保内核启用了led子系统。
配置使能LED子系统：Device Drivers --> LEDs support
内核中设备树参考文档：kernel/Documentation/devicetree/bindings/leds/leds-gpio.txt
编写设备树节点
leds: leds {
compatible = "gpio-leds";
work_led: work {
label = "work_led";
gpios = <&gpio0 RK_PC0 GPIO_ACTIVE_HIGH>;
linux,default-trigger = "heartbeat";
};
run_led: run {
label = "run_led";
gpios = <&gpio0 RK_PA5 GPIO_ACTIVE_HIGH>;
linux,default-trigger = "heartbeat";
};
};
gv_leds: gv-leds {
compatible = "gpio-leds";
pinctrl-names = "default";
pinctrl-0 = <&gv_leds_gpio_fun>;
status = "okay";
led1_u: led1-u {
label = "led1_up";
gpios = <&gpio0 RK_PB0 GPIO_ACTIVE_HIGH>;
default-state = "off";
};
led1_d: led1-d {
label = "led1_down";
gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "off";
};
led2_u: led2-u {
label = "led2_up";
gpios = <&gpio0 RK_PB6 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "off";
};
led2_d: led2-d {
label = "led2_down";
gpios = <&gpio0 RK_PC5 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "off";
};
led_rgb_1: led-rgb-1 {
label = "led_rgb_1";
gpios = <&gpio1 RK_PB0 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "off";
};
led_rgb_2: led-rgb-2 {
label = "led_rgb_2";
gpios = <&gpio1 RK_PB1 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "off";
};
led_rgb_3: led-rgb-3 {
label = "led_rgb_3";
gpios = <&gpio1 RK_PB2 GPIO_ACTIVE_HIGH>;
/* Keep LED on if BIOS detected hardware fault */
default-state = "off";
};
};-
compatible属性：设备树和led子系统匹配的属性，表示这些led使用led子系统。
-
pinctrl-names属性：指定在不同状态下使用不同的引脚配置，这里是default，也就是pinctrl-0指定的属性。
-
pinctrl-0：pinctrl-names为default值时的引脚配置，这里值是gv_leds_gpio_fun。
-
status：表示使能该节点，若想禁用设置修改okay为disable即可。
-
label属性：系统将根据led子节点中的label属性在sysfs中生成相应的目录和设备文件。
-
gpios属性: 该属性指定了控制此led的是哪一个引脚。
-
更多属性配置参考内核中文档。
在pinctl节点增加gpio的配置：
c
gv-leds {
gv_leds_gpio_fun: gv-leds-gpio-fun {
rockchip,pins =
<0 RK_PB0 RK_FUNC_GPIO &pcfg_pull_up>,
<0 RK_PB5 RK_FUNC_GPIO &pcfg_pull_up>,
<0 RK_PB6 RK_FUNC_GPIO &pcfg_pull_up>,
<0 RK_PC5 RK_FUNC_GPIO &pcfg_pull_up>,
<1 RK_PB0 RK_FUNC_GPIO &pcfg_pull_up>,
<1 RK_PB1 RK_FUNC_GPIO &pcfg_pull_up>,
<1 RK_PB2 RK_FUNC_GPIO &pcfg_pull_up>;
};
};如果后续不需要使用只需要将gv_leds设备节点status状态设置为disable。
在实现过程中，部分引脚被占用找到没有生成led的sysfs文件，需要解除引脚占用：
a) 配置内核禁用TouchScreen
b) 禁用以下设备树节点
c
vcc3v3_lcd1_n: vcc3v3-lcd1-n {
compatible = "regulator-fixed";
regulator-name = "vcc3v3_lcd1_n";
regulator-boot-on;
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
enable-active-high;
gpio = <&gpio0 RK_PC5 GPIO_ACTIVE_HIGH>;
vin-supply = <&vcc3v3_sys>;
status = "disable";
regulator-state-mem {
regulator-off-in-suspend;
};
};
&wireless_bluetooth {
compatible = "bluetooth-platdata";
clocks = <&rk809 1>;
clock-names = "ext_clock";
//wifi-bt-power-toggle;
uart_rts_gpios = <&gpio2 RK_PB1 GPIO_ACTIVE_LOW>;
pinctrl-names = "default", "rts_gpio";
pinctrl-0 = <&uart8m0_rtsn>;
pinctrl-1 = <&uart8_gpios>;
BT,reset_gpio = <&gpio3 RK_PA0 GPIO_ACTIVE_HIGH>;
BT,wake_gpio = <&gpio3 RK_PA2 GPIO_ACTIVE_HIGH>;
BT,wake_host_irq = <&gpio3 RK_PA1 GPIO_ACTIVE_HIGH>;
status = "disable";
};
&pcie3x2 {
reset-gpios = <&gpio2 RK_PD6 GPIO_ACTIVE_HIGH>;
vpcie3v3-supply = <&vcc3v3_pcie>;
status = "disable";
}; 将这些节点的status属性设置为"disable"。
用户空间访问
shell
root@M3:~# ls /sys/class/leds/
led_rgb_1/ led_rgb_2/ led_rgb_3/ mmc0::/ run_led/ work_led/
root@M3:~# ls /sys/class/leds/led_rgb_1/
brightness device max_brightness power subsystem trigger uevent
root@M3:~# ls /sys/class/leds/led_rgb_2/
brightness device max_brightness power subsystem trigger uevent
root@M3:~# ls /sys/class/leds/led_rgb_3/
brightness device max_brightness power subsystem trigger uevent通过读写brightness属性就可以控led点亮/关闭。
rightness power subsystem trigger uevent
root@M3:~# ls /sys/class/leds/led_rgb_3/
brightness device max_brightness power subsystem trigger uevent
通过读写brightness属性就可以控led点亮/关闭。