1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * GPIO character device helper for reading chip information.
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-chip-info <chip path> [name|label|num-lines]\n");
20 }
21 
22 int main(int argc, char **argv)
23 {
24 	struct gpiochip_info info;
25 	int fd, ret;
26 
27 	if (argc != 3) {
28 		print_usage();
29 		return EXIT_FAILURE;
30 	}
31 
32 	fd = open(argv[1], O_RDWR);
33 	if (fd < 0) {
34 		perror("unable to open the GPIO chip");
35 		return EXIT_FAILURE;
36 	}
37 
38 	memset(&info, 0, sizeof(info));
39 	ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &info);
40 	if (ret) {
41 		perror("chip info ioctl failed");
42 		return EXIT_FAILURE;
43 	}
44 
45 	if (strcmp(argv[2], "name") == 0) {
46 		printf("%s\n", info.name);
47 	} else if (strcmp(argv[2], "label") == 0) {
48 		printf("%s\n", info.label);
49 	} else if (strcmp(argv[2], "num-lines") == 0) {
50 		printf("%u\n", info.lines);
51 	} else {
52 		fprintf(stderr, "unknown command: %s\n", argv[2]);
53 		return EXIT_FAILURE;
54 	}
55 
56 	return EXIT_SUCCESS;
57 }
58