// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * GPIO character device helper for reading line names.
 *
 * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
 */

#include <fcntl.h>
#include <linux/gpio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>

static void print_usage(void)
{
        printf("usage:\n");
        printf("  gpio-line-name <chip path> <line offset>\n");
}

int main(int argc, char **argv)
{
        struct gpio_v2_line_info info;
        int fd, ret;
        char *endp;

        if (argc != 3) {
                print_usage();
                return EXIT_FAILURE;
        }

        fd = open(argv[1], O_RDWR);
        if (fd < 0) {
                perror("unable to open the GPIO chip");
                return EXIT_FAILURE;
        }

        memset(&info, 0, sizeof(info));
        info.offset = strtoul(argv[2], &endp, 10);
        if (*endp != '\0') {
                print_usage();
                return EXIT_FAILURE;
        }

        ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &info);
        if (ret) {
                perror("line info ioctl failed");
                return EXIT_FAILURE;
        }

        printf("%s\n", info.name);

        return EXIT_SUCCESS;
}