PL设计中MPSoC EMIO GPIO的应用

MPSoC 为PL提供了96个GPIO，通过EMIO管脚链接到PL。

普通PL设计，一般只会用到几个GPIO管脚。可以使用Vivado IPI中的Slice IP， 从其中分出指定数量的管脚。

Slice配置界面

上图中，输入宽度是95，因为pl_reset占用率一个管脚。slice从输入中提取emio的[7:5]三位，作为输出。

Xilinx Linux 中缺省使能了GPIO驱动。对于MPSoC，检查目录/sys/class/gpio，可以看到设备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，可以参考Linux GPIO Driver；GPIO User Space App。

从上述文章可以看到，使用GPIO不简单。

为了简化使用GPIO，编写了以下脚本。使用下列脚本，一条命令就能设置一个GPIO的输出值。脚本接受两个输入参数。第一个参数表示GPIO编号，MIO GPIO从0开始，EMIO GPIO从78开始。第二个参数是输出值。如果输出值是1，可以省略第二个参数。

#/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

执行记录

# ./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

编辑：hfy