Hisilicon 35xx gpio use

Use gpio control

1) Pin multiplexing, in the Hi3520DV400_PINOUT_CN.xlsx manual, select the gpio function

himm 0x120F0008 0

2)
There are 8 GPIOs in one group, and the number of GPIO1_1 is 9
echo 9> /sys/class/gpio/export

3) Set the direction
echo out> /sys/class/gpio/gpio9/direction

4)
Pull high and pull low echo 0> /sys/class/gpio/gpio9/value