Linux_common/comm/commGPIO.c

#include "commGPIO.h"

int gpio_export(int pin)  
{  
    char buffer[64];  
    int len;  
    int fd;  
  
    fd = open("/sys/class/gpio/export", O_WRONLY);  
    if (fd < 0) {  
        MSG("Failed to open export for writing!");  
        return(-1);  
    }  
  
    len = snprintf(buffer, sizeof(buffer), "%d", pin);  
    if (write(fd, buffer, len) < 0) {  
        MSG("Failed to export gpio!");  
        return -1;  
    }  
     
    close(fd);  
    return 0;  
}  

int gpio_unexport(int pin)  
{  
    char buffer[64];  
    int len;  
    int fd;  
  
    fd = open("/sys/class/gpio/unexport", O_WRONLY);  
    if (fd < 0) {  
        MSG("Failed to open unexport for writing!");  
        return -1;  
    }  
  
    len = snprintf(buffer, sizeof(buffer), "%d", pin);  
    if (write(fd, buffer, len) < 0) {  
        MSG("Failed to unexport gpio!");  
        return -1;  
    }  
     
    close(fd);  
    return 0;  
} 

//dir: 0-->IN, 1-->OUT
int gpio_direction(int pin, int dir)  
{  
    static const char dir_str[] = "in\0out";  
    char path[64];  
    int fd;  
  
    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/direction", pin);  
    fd = open(path, O_WRONLY);  
    if (fd < 0) {  
        MSG("Failed to open gpio direction for writing!");  
        return -1;  
    }  
  
    if (write(fd, &dir_str[dir == 0 ? 0 : 3], dir == 0 ? 2 : 3) < 0) {  
        MSG("Failed to set direction!");  
        return -1;  
    }  
  
    close(fd);  
    return 0;  
}  

//value: 0-->LOW, 1-->HIGH
int gpio_write(int pin, int value)  
{  
    static const char values_str[] = "01";  
    char path[64];  
    int fd;  
  
    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);  
    fd = open(path, O_WRONLY);  
    if (fd < 0) {  
        MSG("Failed to open gpio value for writing!");  
        return -1;  
    }  
  
    if (write(fd, &values_str[value == 0 ? 0 : 1], 1) < 0) {  
        MSG("Failed to write value!");  
        return -1;  
    }  
  
    close(fd);  
    return 0;  
}

int gpio_read(int pin)  
{  
    char path[64];  
    char value_str[3];  
    int fd;  
  
    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);  
    fd = open(path, O_RDONLY);  
    if (fd < 0) {  
        MSG("Failed to open gpio value for reading!");  
        return -1;  
    }  
  
    if (read(fd, value_str, 3) < 0) {  
        MSG("Failed to read value!");  
        return -1;  
    }  
  
    close(fd);  
    return (atoi(value_str));
}  

// none表示引脚为输入，不是中断引脚
// rising表示引脚为中断输入，上升沿触发
// falling表示引脚为中断输入，下降沿触发
// both表示引脚为中断输入，边沿触发
// 0-->none, 1-->rising, 2-->falling, 3-->both
int gpio_edge(int pin, int edge)
{
	const char dir_str[] = "none\0rising\0falling\0both"; 
	int ptr;
	char path[64];  
	int fd; 

	switch(edge){
	case 0:
		ptr = 0;
		break;
	case 1:
		ptr = 5;
		break;
	case 2:
		ptr = 12;
		break;
	case 3:
		ptr = 20;
		break;
	default:
		ptr = 0;
		break;
	} 
  
    snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/edge", pin);  
    fd = open(path, O_WRONLY);  
    if (fd < 0) {  
        MSG("Failed to open gpio edge for writing!");  
        return -1;  
    }  
  
    if (write(fd, &dir_str[ptr], strlen(&dir_str[ptr])) < 0) {  
        MSG("Failed to set edge!");  
        return -1;  
    }  
  
    close(fd);  
    return 0;  
}

//实现中断检测函数
//GPIO1_17
int main_test()  
{  
	int gpio_fd, ret;
	struct pollfd fds[1];
	char buff[10];
	unsigned char cnt = 0;
	//LED引脚初始化
	gpio_export(115);
	gpio_direction(115, 1);
	gpio_write(115, 0);

	//按键引脚初始化
	gpio_export(49);
	gpio_direction(49, 0);
	gpio_edge(49,1);
	gpio_fd = open("/sys/class/gpio/gpio49/value",O_RDONLY);
	if(gpio_fd < 0){
		MSG("Failed to open value!");  
		return -1;  
	}
	fds[0].fd = gpio_fd;
	fds[0].events  = POLLPRI;
	ret = read(gpio_fd,buff,10);
	if( ret == -1 )
		MSG("read");

	while(1){
		ret = poll(fds,1,0);
		if( ret == -1 )
			MSG("poll\n");
		if( fds[0].revents & POLLPRI){
			ret = lseek(gpio_fd,0,SEEK_SET);
			if( ret == -1 )
				MSG("lseek");

			ret = read(gpio_fd,buff,10);
			if( ret == -1 )
				MSG("read");

			gpio_write(115, cnt++%2);
		}
		usleep(100000);
	}
	return 0;
}