1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * GPIO character device helper for reading line names.
4 *
5 * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
6 */
7
8#include <fcntl.h>
9#include <linux/gpio.h>
10#include <stdio.h>
11#include <stdlib.h>
12#include <string.h>
13#include <sys/ioctl.h>
14#include <sys/types.h>
15
16static void print_usage(void)
17{
18	printf("usage:\n");
19	printf("  gpio-line-name <chip path> <line offset>\n");
20}
21
22int main(int argc, char **argv)
23{
24	struct gpio_v2_line_info info;
25	int fd, ret;
26	char *endp;
27
28	if (argc != 3) {
29		print_usage();
30		return EXIT_FAILURE;
31	}
32
33	fd = open(argv[1], O_RDWR);
34	if (fd < 0) {
35		perror("unable to open the GPIO chip");
36		return EXIT_FAILURE;
37	}
38
39	memset(&info, 0, sizeof(info));
40	info.offset = strtoul(argv[2], &endp, 10);
41	if (*endp != '\0') {
42		print_usage();
43		return EXIT_FAILURE;
44	}
45
46	ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &info);
47	if (ret) {
48		perror("line info ioctl failed");
49		return EXIT_FAILURE;
50	}
51
52	printf("%s\n", info.name);
53
54	return EXIT_SUCCESS;
55}
56