MPSoC 為PL提供了96個GPIO，通過EMIO管腳鏈接到PL。

普通PL設計，一般只會用到幾個GPIO管腳。可以使用Vivado IPI中的Slice IP， 從其中分出指定數量的管腳。

Slice配置界面

上圖中，輸入寬度是95，因為pl_reset占用率一個管腳。slice從輸入中提取emio的[7:5]三位，作為輸出。

Xilinx Linux 中缺省使能了GPIO驅動。對于MPSoC，檢查目錄/sys/class/gpio，可以看到設備gpiochip338。

# ls -l /sys/class/gpio
total 0
export
gpiochip306 -> ../../devices/platform/amba/ff020000.i2c/i2c-0/0-0021/gpio/gpiochip306
gpiochip322 ->../../devices/platform/amba/ff020000.i2c/i2c-0/0-0020/gpio/gpiochip322
gpiochip338 -> ../../devices/platform/amba/ff0a0000.gpio/gpio/gpiochip338
unexport

# ls /sys/class/gpio/gpiochip338/ -l
total 0
base
device -> ../../../ff0a0000.gpio
label
ngpio
power
subsystem -> ../../../../../../class/gpio
uevent

Linux GPIO Driver下的GPIO使用，可以參考Linux GPIO Driver；GPIO User Space App。

從上述文章可以看到，使用GPIO不簡單。

為了簡化使用GPIO，編寫了以下腳本。使用下列腳本，一條命令就能設置一個GPIO的輸出值。腳本接受兩個輸入參數。第一個參數表示GPIO編號，MIO GPIO從0開始，EMIO GPIO從78開始。第二個參數是輸出值。如果輸出值是1，可以省略第二個參數。

#/bin/bash

function gpio_output_func()
{

    #echo "No.1 parameter: $1"
    #echo "No.2 parameter: $2"    
    
    # MPSoC GPIO number.
    gpio_num=$[338+$1]
    
    # MPSoC EMIO GPIO number.
    # gpio_num=$[338+78+$1]
    
    echo "Set GPIO number: $gpio_num to value: $2"

    if [ ! -f /sys/class/gpio/gpio$gpio_num/direction ]; then 
        #  Export a GPIO pin
        echo $gpio_num > /sys/class/gpio/export
    fi      
    
    #  Read the direction and value from the GPIO pin */
    # ls -l /sys/class/gpio/gpio$gpio_num/
	
    gpio_direction=`cat /sys/class/gpio/gpio$gpio_num/direction`
    gpio_value=`cat /sys/class/gpio/gpio$gpio_num/value`
    echo -e "GPIO number: $gpio_num previous direction: $gpio_direction, previous value: $gpio_value/b"
      
    #  Set the direction to an output and write a value 1 to GPIO pin */
    echo out > /sys/class/gpio/gpio$gpio_num/direction
    echo $2 > /sys/class/gpio/gpio$gpio_num/value
	
    gpio_direction=`cat /sys/class/gpio/gpio$gpio_num/direction`
    gpio_value=`cat /sys/class/gpio/gpio$gpio_num/value`
    echo -e "GPIO number: $gpio_num current direction: $gpio_direction, current value: $gpio_value/b"

}

# Check GPIO chip
gpio_chip=`cat /sys/class/gpio/gpiochip338/label`
gpio_base=`cat /sys/class/gpio/gpiochip338/base`
gpio_number=`cat /sys/class/gpio/gpiochip338/ngpio`
echo "MPSoC GPIO information: chip: $gpio_chip, base: $gpio_base, number: $gpio_number."
# cat /sys/class/gpio/gpiochip338/label
# cat /sys/class/gpio/gpiochip338/base
# cat /sys/class/gpio/gpiochip338/ngpio
# The above line indicates that gpio 0th pin starts from 338 and ends at 511 (GPIO has total 174 pins for ZynqMP)

if [ "$2" = "" ]; then
    gpio_output_func $1 1 
else
    gpio_output_func $1 $2
fi

執行記錄

# ./gpio_single_output.sh 81
MPSoC GPIO information: chip: zynqmp_gpio, base: 338, number: 174.
Set GPIO number: 419 to value: 1
GPIO number: 419 previous direction: out, previous value: 0
GPIO number: 419 current direction: out, current value: 1

# ./gpio_single_output.sh 81 0
MPSoC GPIO information: chip: zynqmp_gpio, base: 338, number: 174.
Set GPIO number: 419 to value: 0
GPIO number: 419 previous direction: out, previous value: 1
GPIO number: 419 current direction: out, current value: 0