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/*
* lsgpio - example on how to list the GPIO lines on a system
*
* Copyright (C) 2015 Linus Walleij
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* Usage:
* lsgpio <-n device-name>
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <dirent.h>
#include <errno.h>
#include <string.h>
#include <poll.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/ioctl.h>
#include <linux/gpio.h>
#include "gpio-utils.h"
int list_device(const char *device_name)
{
struct gpiochip_info cinfo;
char *chrdev_name;
int fd;
int ret;
ret = asprintf(&chrdev_name, "/dev/%s", device_name);
if (ret < 0)
return -ENOMEM;
fd = open(chrdev_name, 0);
if (fd == -1) {
ret = -errno;
fprintf(stderr, "Failed to open %s\n", chrdev_name);
goto free_chrdev_name;
}
/* Inspect this GPIO chip */
ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to retrieve GPIO fd\n");
if (close(fd) == -1)
perror("Failed to close GPIO character device file");
goto free_chrdev_name;
}
fprintf(stdout, "GPIO chip: %s, %u GPIO lines\n",
cinfo.name, cinfo.lines);
if (close(fd) == -1) {
ret = -errno;
goto free_chrdev_name;
}
free_chrdev_name:
free(chrdev_name);
return ret;
}
void print_usage(void)
{
fprintf(stderr, "Usage: lsgpio [options]...\n"
"List GPIO chips, lines and states\n"
" -n <name> List GPIOs on a named device\n"
" -? This helptext\n"
);
}
int main(int argc, char **argv)
{
const char *device_name;
int ret;
int c;
while ((c = getopt(argc, argv, "n:")) != -1) {
switch (c) {
case 'n':
device_name = optarg;
break;
case '?':
print_usage();
return -1;
}
}
if (device_name)
ret = list_device(device_name);
else {
const struct dirent *ent;
DIR *dp;
/* List all GPIO devices one at a time */
dp = opendir("/dev");
if (!dp) {
ret = -errno;
goto error_out;
}
ret = -ENOENT;
while (ent = readdir(dp), ent) {
if (check_prefix(ent->d_name, "gpiochip")) {
ret = list_device(ent->d_name);
if (ret)
break;
}
}
ret = 0;
if (closedir(dp) == -1) {
perror("scanning devices: Failed to close directory");
ret = -errno;
}
}
error_out:
return ret;
}
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