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| #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <poll.h>
#define SYSFS_GPIO_DIR "/sys/class/gpio"
#define MAX_BUF 255
int gpio_export(unsigned int gpio)
{
int fd, len;
char buf[MAX_BUF];
fd = open(SYSFS_GPIO_DIR "/export", O_WRONLY);
if (fd < 0) {
fprintf(stderr, "Can't export GPIO %d pin: %s\n", gpio, strerror(errno));
return fd;
}
len = snprintf(buf, sizeof(buf), "%d", gpio);
write(fd, buf, len);
close(fd);
return 0;
}
int gpio_unexport(unsigned int gpio)
{
int fd, len;
char buf[MAX_BUF];
fd = open(SYSFS_GPIO_DIR "/unexport", O_WRONLY);
if (fd < 0) {
fprintf(stderr, "Can't unexport GPIO %d pin: %s\n", gpio, strerror(errno));
return fd;
}
len = snprintf(buf, sizeof(buf), "%d", gpio);
write(fd, buf, len);
close(fd);
return 0;
}
int gpio_set_edge(unsigned int gpio, char *edge)
{
int fd, len;
char buf[MAX_BUF];
len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/edge", gpio);
fd = open(buf, O_WRONLY);
if (fd < 0) {
fprintf(stderr, "Can't set GPIO %d pin edge: %s\n", gpio, strerror(errno));
return fd;
}
write(fd, edge, strlen(edge)+1);
close(fd);
return 0;
}
int gpio_set_pull(unsigned int gpio, char *pull)
{
int fd, len;
char buf[MAX_BUF];
len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/pull", gpio);
fd = open(buf, O_WRONLY);
if (fd < 0) {
fprintf(stderr, "Can't set GPIO %d pin pull: %s\n", gpio, strerror(errno));
return fd;
}
write(fd, pull, strlen(pull)+1);
close(fd);
return 0;
}
int main(int argc, char *argv[])
{
struct pollfd fdset[2];
int fd, ret, gpio;
char buf[MAX_BUF];
if (argc < 3 || argc > 4) {
fprintf(stdout, "usage : sudo sysfs_irq_test <gpio> <edge> [pull]\n");
fflush(stdout);
return -1;
}
gpio = atoi(argv[1]);
if (gpio_export(gpio)) {
fprintf(stdout, "error : export %d\n", gpio);
fflush(stdout);
return -1;
}
if (gpio_set_edge(gpio, argv[2])) {
fprintf(stdout, "error : edge %s\n", argv[2]);
fflush(stdout);
return -1;
}
if (argv[3] && gpio_set_pull(gpio, argv[3])) {
fprintf(stdout, "error : pull %s\n", argv[3]);
fflush(stdout);
return -1;
}
snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
fd = open(buf, O_RDWR);
if (fd < 0)
goto out;
while (1) {
memset(fdset, 0, sizeof(fdset));
fdset[0].fd = STDIN_FILENO;
fdset[0].events = POLLIN;
fdset[1].fd = fd;
fdset[1].events = POLLPRI;
ret = poll(fdset, 2, 3*1000);
if (ret < 0) {
perror("poll");
break;
}
fprintf(stderr, ".");
if (fdset[1].revents & POLLPRI) {
char c;
(void)read (fd, &c, 1) ;
lseek (fd, 0, SEEK_SET) ;
fprintf(stderr, "\nGPIO %d interrupt occurred!\n", gpio);
}
if (fdset[0].revents & POLLIN)
break;
fflush(stdout);
}
close(fd);
out:
if (gpio_unexport(gpio)) {
fprintf(stdout, "error : unexport %d\n", gpio);
fflush(stdout);
}
return 0;
}
|