海思GPIO中输入的一种测试方法

 海思提供一在应用层测试GPIO的函数，只需要将其使用，即可完成GPIO的输入输出等功能测试，本文是测试一下海思GPIO的输入功能。

1、测试源码：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

int gpio_test_in(unsigned int gpio_chip_num, unsigned int gpio_offset_num)
{
        FILE *fp;
        char file_name[50];
        unsigned char buf[10];
        unsigned int gpio_num;

        gpio_num = gpio_chip_num * 8 + gpio_offset_num;

        sprintf(file_name, "/sys/class/gpio/export");
        fp = fopen(file_name, "w");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        fprintf(fp, "%d", gpio_num);
        fclose(fp);

        sprintf(file_name, "/sys/class/gpio/gpio%d/direction", gpio_num);
        fp = fopen(file_name, "rb+");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        fprintf(fp, "in");
        fclose(fp);

        sprintf(file_name, "/sys/class/gpio/gpio%d/value", gpio_num);
        fp = fopen(file_name, "rb+");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        memset(buf, 0, 10);
        fread(buf, sizeof(char), sizeof(buf) - 1, fp);
        printf("%s: gpio%d_%d = %d\n", __func__,
                        gpio_chip_num, gpio_offset_num, buf[0]-48);
       fclose(fp);
        sprintf(file_name, "/sys/class/gpio/unexport");
        fp = fopen(file_name, "w");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        fprintf(fp, "%d", gpio_num);
        fclose(fp);

        return (int)(buf[0]-48);
}

int gpio_test_out(unsigned int gpio_chip_num, unsigned int gpio_offset_num,
                unsigned int gpio_out_val)
{
        FILE *fp;
        char file_name[50];
        unsigned char buf[10];
        unsigned int gpio_num;

        gpio_num = gpio_chip_num * 8 + gpio_offset_num;

        sprintf(file_name, "/sys/class/gpio/export");
        fp = fopen(file_name, "w");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        fprintf(fp, "%d", gpio_num);
        fclose(fp);

        sprintf(file_name, "/sys/class/gpio/gpio%d/direction", gpio_num);
        fp = fopen(file_name, "rb+");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        fprintf(fp, "out");
        fclose(fp);

        sprintf(file_name, "/sys/class/gpio/gpio%d/value", gpio_num);
        fp = fopen(file_name, "rb+");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        if (gpio_out_val)
                strcpy(buf,"1");
        else
                strcpy(buf,"0");

        fwrite(buf, sizeof(char), sizeof(buf) - 1, fp);
        printf("%s: gpio%d_%d = %s\n", __func__,
                        gpio_chip_num, gpio_offset_num, buf);
        fclose(fp);

        sprintf(file_name, "/sys/class/gpio/unexport");
        fp = fopen(file_name, "w");
        if (fp == NULL) {
                printf("Cannot open %s.\n", file_name);
                return -1;
        }
        fprintf(fp, "%d", gpio_num);
        fclose(fp);

        return 0;

}
				
int main(int argc, const char *argv[])
{

		if (argc != 4)
			{
			printf("Usage %s : gpio_chip_num : gpio_offset_num : gpio_out_val!\n",argv[0]);
			printf("gpio_out_val = 1 is high level,gpio_out_val = 0 is low level!\n");
			return -1;
			}
		int gpio_chip_num = atoi(argv[1]);
		int gpio_offset_num = atoi(argv[2]);
		int gpio_out_val = atoi(argv[3]);
		int i = 0;
		for(i=0;i<20;i++)
		{
			if(0 == i%2)
			{
			printf("i = %d\n",i+1);
			gpio_test_out(gpio_chip_num,gpio_offset_num,gpio_out_val);
			
			usleep(200000);
			}
			else
			{
			printf("i = %d\n",i+1);
			gpio_test_out(gpio_chip_num,gpio_offset_num,!gpio_out_val);
			usleep(200000);
			}
		}
		
	printf("test_gpio over!\n");
return 0;
	
}

2、我使用的仍是传参方式，下面的测试我使用的是是GPIO3_1，所以传参为 3 1 1。将上面的源码编译成ELF文件，拷贝至开发板下。 

3、运行该程序。

4、我将其连接至一个IO测试板子中，发现小灯在循环闪烁20次后结束，与预想的一样。

至此即完成GPIO的输入测试，可以在此基础上修改代码，完成自己想要的功能。