OpenWRT 系统的 gpio 可用配置为键盘输入、led输出、控制输出等，以 mt7621 为例，相互关系说明如下：
第一步 查看设备树配置文件
/OpenWrt/mtk7621-19.07$ ls target/linux/ramips/dts/ | grep 7621
AP-MT7621A-V60.dts
MT7621.dts
mt7621.dtsi #（1） mt7621 芯片资源的基本配置文件
U7621-06-256M-16M.dts # (3) U7621-06-256M-16M 用户板级 分区配置文件
U7621-06-256M-64M.dts
U7621-06-512M-64M.dts
U7621-06.dtsi # （2） U7621-06 用户板级的配置文件
（1） mt7621 芯片资源的基本配置文件
#include <dt-bindings/interrupt-controller/mips-gic.h>
#include <dt-bindings/clock/mt7621-clk.h>
/ {
#address-cells = <1>;
#size-cells = <1>;
compatible = "mediatek,mt7621-soc";
cpus {
#address-cells = <1>;
#size-cells = <0>;
cpu@0 {
device_type = "cpu";
compatible = "mips,mips1004Kc";
reg = <0>;
};
cpu@1 {
device_type = "cpu";
compatible = "mips,mips1004Kc";
reg = <1>;
};
};
cpuintc: cpuintc {
#address-cells = <0>;
#interrupt-cells = <1>;
interrupt-controller;
compatible = "mti,cpu-interrupt-controller";
};
aliases {
serial0 = &uartlite;
};
pll: pll {
compatible = "mediatek,mt7621-pll", "syscon";
#clock-cells = <1>;
clock-output-names = "cpu", "bus";
};
sysclock: sysclock {
#clock-cells = <0>;
compatible = "fixed-clock";
/* FIXME: there should be way to detect this */
clock-frequency = <50000000>;
};
省略部分
（2） U7621-06 用户板级的配置文件
注意配置文件中 leds 、keys 和 pinctrl 中的 state_default 此部分是对,mt7621.dtsi 中的gpio属性的重写，意思是可用作为gpio端口使用的特殊声明。
#include "mt7621.dtsi"
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/input/input.h>
/ {
compatible = "unielec,u7621-06", "mediatek,mt7621-soc";
/* compatible = "mediatek,mt7621-soc";*/
aliases {
led-boot = &led_status;
led-failsafe = &led_status;
led-running = &led_status;
led-upgrade = &led_status;
};
chosen {
bootargs = "console=ttyS0,57600";
};
gpio-export {
compatible = "gpio-export";
#size-cells = <0>;
modem_reset {
gpio-export,name = "modem_reset";
gpio-export,output = <1>;
gpios = <&gpio0 16 GPIO_ACTIVE_LOW>;
};
};
keys {
compatible = "gpio-keys-polled";
poll-interval = <20>;
reset {
label = "reset";
gpios = <&gpio0 18 GPIO_ACTIVE_LOW>;
linux,code = <KEY_RESTART>;
};
};
leds {
compatible = "gpio-leds";
led_status: status {
label = "u7621-06:green:status";
gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
};
led4 {
label = "u7621-06:green:led4";
gpios = <&gpio0 14 GPIO_ACTIVE_HIGH>;
};
led5 {
label = "u7621-06:green:led5";
gpios = <&gpio0 15 GPIO_ACTIVE_HIGH>;
};
lan1 {
label = "u7621-06:green:lan1";
gpios = <&gpio0 17 GPIO_ACTIVE_HIGH>;
};
};
};
&gpio0 {
status = "okay";
};
&sdhci {
status = "okay";
};
&pcie {
status = "okay";
};
ðernet {
mtd-mac-address = <&factory 0xe000>;
mediatek,portmap = "llllw";
};
//Date: 2021-5-28
&uartlite2 {
status = "okay";
};
&uartlite3 {
status = "okay";
};
&gdma {
status = "okay";
};
&hsdma {
status = "okay";
};
&pinctrl {
state_default: pinctrl0 {
gpio {
// ralink,group = "jtag", "uart2", "wdt";
ralink,group = "jtag","wdt";
ralink,function = "gpio";
};
};
};
如 jtag 口做为普通 io 使用；如果笔者封闭那行中，包含 uart2 口；如果不取出的话，uart2 就无法打开成功。
第二步 对应的驱动文件
compatible = “gpio-keys-polled”;驱动文件位置：
build_dir/target-mipsel_24kc_musl/linux-ramips_mt7621/linux-4.14.200$ ls drivers/input/keyboard/gpio_keys.c
drivers/input/keyboard/gpio_keys.c
compatible = “gpio-leds”; 驱动文件位置：
build_dir/target-mipsel_24kc_musl/linux-ramips_mt7621/linux-4.14.200$ ls drivers/leds/leds-gpio.c
drivers/leds/leds-gpio.c
第三步 配置 led 的对应关系
配置 led 的对应关系，请参考此路径文件:
ls target/linux/ramips/base-files/etc/board.d/01_leds
target/linux/ramips/base-files/etc/board.d/01_leds
详细内容如下：
#!/bin/sh
. /lib/functions/uci-defaults.sh
set_wifi_led() {
ucidef_set_led_netdev "wifi_led" "wifi" "${1}" "${2:-wlan0}"
}
board=$(board_name)
boardname="${board##*,}"
board_config_update
case $board in
3g-6200n|\
br-6475nd|\
mzk-w300nh2)
set_wifi_led "$boardname:amber:wlan"
;;
3g-6200nl|\
air3gii|\
hilink,hlk-7628n|\
mr-102n|\
skylab,skw92a|\
wnce2001|\
zbt-we2026)
set_wifi_led "$boardname:green:wlan"
;;
ai-br100)
ucidef_set_led_netdev "wan" "wan" "$boardname:blue:wan" "eth0.2"
set_wifi_led "$boardname:blue:wlan"
;;
alfa-network,ac1200rm)
set_wifi_led "$boardname:green:wlan2g" "wlan1"
;;
alfa-network,awusfree1|\
edimax,br-6478ac-v2)
set_wifi_led "$boardname:blue:wlan"
;;
alfa-network,r36m-e4g)
ucidef_set_led_netdev "4g" "4g" "$boardname:orange:4g" "wwan0"
ucidef_set_led_switch "lan" "lan" "$boardname:green:lan" "switch0" "0x8"
ucidef_set_led_switch "wan" "wan" "$boardname:green:wan" "switch0" "0x10"
;;
alfa-network,tube-e4g)
ucidef_set_led_netdev "4g" "4g" "$boardname:green:4g" "wwan0"
ucidef_set_led_netdev "lan" "lan" "$boardname:blue:lan" "eth0"
;;
all0256n-4M|\
all0256n-8M)
ucidef_set_rssimon "wlan0" "200000" "1"
ucidef_set_led_rssi "rssilow" "RSSILOW" "all0256n:green:rssilow" "wlan0" "1" "40" "0" "6"
ucidef_set_led_rssi "rssimedium" "RSSIMEDIUM" "all0256n:green:rssimed" "wlan0" "30" "80" "-29" "5"
ucidef_set_led_rssi "rssihigh" "RSSIHIGH" "all0256n:green:rssihigh" "wlan0" "70" "100" "-69" "8"
set_wifi_led "rt2800pci-phy0::radio"
;;
zbt-we826-16M|\
zbt-we826-32M)
set_wifi_led "zbt-we826:green:wifi"
;;
zbtlink,zbt-we1226)
set_wifi_led "$boardname:green:wlan"
ucidef_set_led_switch "lan1" "LAN1" "$boardname:green:lan1" "switch0" "0x01"
ucidef_set_led_switch "lan2" "LAN2" "$boardname:green:lan2" "switch0" "0x02"
ucidef_set_led_switch "wan" "WAN" "$boardname:green:wan" "switch0" "0x10"
;;
zorlik,zl5900v2)
ucidef_set_led_netdev "lan" "lan" "$boardname:green:lan" eth0
;;
zyxel,keenetic-extra-ii)
set_wifi_led "$boardname:green:wifi"
ucidef_set_led_switch "internet" "internet" "$boardname:green:internet" "switch0" "0x01"
;;
youku-yk1)
set_wifi_led "$boardname:blue:air"
ucidef_set_led_switch "wan" "wan" "$boardname:blue:wan" "switch0" "0x10"
;;
esac
board_config_flush
exit 0
此文件目的是备忘使用。