/**
* @author emlsyx
* @email yangx_1118@163.com
* @create date 2020-02-19 19:11:53
* @modify date 2020-02-19 19:11:53
* @desc [description]
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/poll.h>
#define err_out(fmt, ...)
do
{
printf(fmt, ##__VA_ARGS__);
printf("<%s> "%s()" %d error
", __FILE__, __FUNCTION__, __LINE__);
} while (0)
#define open_gpio_file(path, flag, fd)
do
{
fd = open(path, flag);
if (fd < 0)
{
err_out(""%s" open failed
", path);
return (-1);
}
} while (0);
/**
* @brief : gpio 导出
* @param : pin
* @retval: 0 成功; -1失败
*/
static int gpio_export(const int pin)
{
int fd, len;
char buffer[64];
char path[64];
sprintf(&path[0], "/sys/class/gpio/gpio%d", pin);
/* 文件不存在时，导出gpio*/
if (access(path, F_OK) != 0)
{
memset(path, 0, 64);
sprintf(&path[0], "/sys/class/gpio/export");
open_gpio_file(path, O_WRONLY, fd);
len = snprintf(buffer, sizeof(buffer), "%d", pin);
if (write(fd, buffer, len) < 0)
{
err_out("write failed to export gpio!
");
return -1;
}
close(fd);
}
return 0;
}
/**
* @brief : gpio 卸载
* @param : pin
* @retval: 0 成功; -1失败
*/
static int gpio_unexport(const int pin)
{
int fd, len;
char buffer[64];
char path[64];
sprintf(&path[0], "/sys/class/gpio/gpio%d", pin);
/* 文件存在时，卸载gpio*/
if (access(path, F_OK) == 0)
{
memset(path, 0, 64);
sprintf(&path[0], "/sys/class/gpio/unexport");
open_gpio_file(path, O_WRONLY, fd);
len = snprintf(buffer, sizeof(buffer), "%d", pin);
if (write(fd, buffer, len) < 0)
{
err_out("write failed to unexport gpio!
");
return -1;
}
close(fd);
}
return 0;
}
/**
* @brief : gpio 方向控制
* @param : dir 方向(in/out)
* @retval: 0 成功; -1失败
*/
static int gpio_direction(const int pin, const char *dir)
{
int fd;
char path[64];
int w_len = ((dir[0] == 'i') && (dir[1] == 'n')) ? 2 : 3;
snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/direction", pin);
open_gpio_file(path, O_WRONLY, fd);
if (write(fd, dir, w_len) < 0)
{
err_out("Failed to set direction!
");
return -1;
}
close(fd);
return 0;
}
/**
* @brief : gpio 写
* @param : 0 / 1
* @retval: 0 成功; -1失败
*/
static int gpio_write(const int pin, const int value)
{
int fd;
char path[64];
const char *val[] = {"0", "1"};
snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);
open_gpio_file(path, O_WRONLY, fd);
if (write(fd, val[value], 1) < 0)
{
err_out("Failed to write value!
");
return -1;
}
close(fd);
return 0;
}
/**
* @brief : gpio 读
* @param : 读取的引脚值
* @retval: 返回引脚的值 0 / 1
*/
static int gpio_read(const int pin)
{
int fd;
char path[64];
char value_str[3];
snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/value", pin);
open_gpio_file(path, O_RDONLY, fd);
if (read(fd, value_str, 3) < 0)
{
err_out("Failed to read value!
");
return -1;
}
close(fd);
return (atoi(value_str));
}
/**
* @brief : gpio 中断控制
* @param : 0 none 表示引脚为输入，不是中断引脚
* @arg : 1 rising 表示引脚为中断输入，上升沿触发
* @arg : 2 falling 表示引脚为中断输入，下降沿触发
* @arg : 3 both 表示引脚为中断输入，边沿触发
* @retval:
*/
static int gpio_edge(const int pin, int edge)
{
int fd;
char path[64];
const char *dir_str[] = {"none", "rising", "falling", "both"};
if (edge > 3)
{
err_out("Failed edge parameter error
");
return -1;
}
snprintf(path, sizeof(path), "/sys/class/gpio/gpio%d/edge", pin);
open_gpio_file(path, O_WRONLY, fd);
if (write(fd, dir_str[edge], strlen(dir_str[edge])) < 0)
{
err_out("Failed to set edge!
");
return -1;
}
close(fd);
return 0;
}
int main()
{
char buff[10], res;
int led_fd, key_fd;
struct pollfd fds;
/* 按键led指示灯*/
gpio_export(55);
gpio_direction(55, "out");
gpio_write(55, 0);
/* 按键引脚初始化*/
gpio_export(70);
gpio_direction(70, "in");
gpio_edge(70, 2);
open_gpio_file("/sys/class/gpio/gpio70/value", O_RDONLY, key_fd);
/* poll 操作的文件符号*/
fds.fd = key_fd;
/* 经测试io中断产生后，正常会发送POLLPRI 这个中断，循环中必须等待这个事件*/
fds.events = POLLPRI | POLLERR;
/* 真实发生的事件*/
fds.revents = 0;
while (1)
{
int ret = poll(&fds, 1, -1);
if (!ret)
{
err_out("poll time out
");
}
else
{
if (fds.revents & POLLPRI)
{
gpio_write(55, gpio_read(55) ? 0 : 1);
res = lseek(fds.fd, 0, SEEK_SET); /* 读取按键值*/
if (res == -1)
{
printf("lseek failed!
");
return -1;
}
res = read(fds.fd, buff, sizeof(buff));
if (res == -1)
{
perror("read failed!
");
return -1;
}
printf("fds.revents %d key value %s
", fds.revents, buff);
}
}
}
return 0;
}
