基于MT7981方案把GPIO 22和23配置成UART功能方法

修改 mt7981-spim-nor-rfb.dts文件。如下所示：

zw@ubuntu:~/Work/OpwnWrt_Src/openwrt2102/build_dir/target-aarch64_cortex-a53_musl/linux-mediatek_mt7981/linux-5.4.246/arch/arm64/boot/dts/mediatek$ cat  mt7981-spim-nor-rfb.dts

/dts-v1/;

#include "mt7981.dtsi"

/ {

model = "MediaTek MT7981 RFB";

compatible = "mediatek,mt7981-spim-nor-rfb";

chosen {

bootargs = "console=ttyS0,115200n1 loglevel=8  \

earlycon=uart8250,mmio32,0x11002000";

};

memory {

// fpga ddr2: 128MB*2

reg = <0 0x40000000 0 0x10000000>;

};

gpio-keys {

compatible = "gpio-keys";

reset {

label = "reset";

linux,code = <KEY_RESTART>;

gpios = <&pio 1 GPIO_ACTIVE_LOW>;

};

        };

gpio-leds {

                compatible = "gpio-leds";

wan {

                        label = "blue:wan";

                        gpios = <&pio 16 GPIO_ACTIVE_LOW>;

                };

wwan {

                        label = "blue:wwan";

                        gpios = <&pio 19 GPIO_ACTIVE_LOW>;

                };

                ap1 {

                        label = "blue:ap1";

                        gpios = <&pio 4 GPIO_ACTIVE_HIGH>;

                };

ap2 {

                        label = "blue:ap2";

                        gpios = <&pio 5 GPIO_ACTIVE_HIGH>;

                };

ap3 {

                        label = "blue:ap3";

                        gpios = <&pio 6 GPIO_ACTIVE_HIGH>;

  &nbs