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// SPDX-License-Identifier: GPL-2.0-or-later
// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
/* Minimal example of finding a line with the given name. */
#include <dirent.h>
#include <errno.h>
#include <gpiod.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
static int chip_dir_filter(const struct dirent *entry)
{
struct stat sb;
int ret = 0;
char *path;
if (asprintf(&path, "/dev/%s", entry->d_name) < 0)
return 0;
if ((lstat(path, &sb) == 0) && (!S_ISLNK(sb.st_mode)) &&
gpiod_is_gpiochip_device(path))
ret = 1;
free(path);
return ret;
}
static int all_chip_paths(char ***paths_ptr)
{
int i, j, num_chips, ret = 0;
struct dirent **entries;
char **paths;
num_chips = scandir("/dev/", &entries, chip_dir_filter, versionsort);
if (num_chips < 0)
return 0;
paths = calloc(num_chips, sizeof(*paths));
if (!paths)
return 0;
for (i = 0; i < num_chips; i++) {
if (asprintf(&paths[i], "/dev/%s", entries[i]->d_name) < 0) {
for (j = 0; j < i; j++)
free(paths[j]);
free(paths);
return 0;
}
}
*paths_ptr = paths;
ret = num_chips;
for (i = 0; i < num_chips; i++)
free(entries[i]);
free(entries);
return ret;
}
int main(void)
{
/* Example configuration - customize to suit your situation. */
static const char *const line_name = "GPIO19";
struct gpiod_chip_info *cinfo;
int i, num_chips, offset;
struct gpiod_chip *chip;
char **chip_paths;
/*
* Names are not guaranteed unique, so this finds the first line with
* the given name.
*/
num_chips = all_chip_paths(&chip_paths);
for (i = 0; i < num_chips; i++) {
chip = gpiod_chip_open(chip_paths[i]);
if (!chip)
continue;
offset = gpiod_chip_get_line_offset_from_name(chip, line_name);
if (offset == -1)
goto close_chip;
cinfo = gpiod_chip_get_info(chip);
if (!cinfo)
goto close_chip;
printf("%s: %s %d\n", line_name,
gpiod_chip_info_get_name(cinfo), offset);
return EXIT_SUCCESS;
close_chip:
gpiod_chip_close(chip);
}
printf("line '%s' not found\n", line_name);
return EXIT_FAILURE;
}
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