T113 在uboot中读写GPIO

在T113中按了Power 键之后给 PD15高电平（电源Enable脚）
vim /brandy/boot-2018/board/sunxi/board.c

int board_init(void){
    ...
    pr_msg("kk-boot-test:board_init \n");   // 并没有打印
    sunxi_gpio_set_cfgpin(111, SUNXI_GPIO_OUTPUT);    // 111设置为输出
    gpio_direction_output(111, 1);    // 输出高电平

    ...

}

./build.sh brandy
./build.sh pack

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PD15 (output) - Power Enable:  3*32+15 = 111

PE13 (input) - Power Switch:  4*32+13 = 141
PD15 (output) - Power Enable:  3*32+15 = 111

#PE13 - Power Switch
echo 141 > /sys/class/gpio/export
echo in > /sys/class/gpio/gpio141/direction
cat /sys/class/gpio/gpio141/value

#PD15 - Power Enable
echo 111 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio111/direction
echo 1 > /sys/class/gpio/gpio111/value
echo 0 > /sys/class/gpio/gpio111/value