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 
16 static void print_usage(void)
17 {
18 	printf("usage:\n");
19 	printf("  gpio-line-name <chip path> <line offset>\n");
20 }
21 
22 int 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