在PL设计中使用MPSoC EMIO GPIO

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: $gpio_value" # Set the direction to an output and write a value 1 to GPIO pin */ echo out > /sys/class/gpio/gpio$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" } # 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