| /* |
| * lsgpio - example on how to list the GPIO lines on a system |
| * |
| * Copyright (C) 2015 Linus Walleij |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 as published by |
| * the Free Software Foundation. |
| * |
| * Usage: |
| * lsgpio <-n device-name> |
| */ |
| |
| #include <unistd.h> |
| #include <stdlib.h> |
| #include <stdbool.h> |
| #include <stdio.h> |
| #include <dirent.h> |
| #include <errno.h> |
| #include <string.h> |
| #include <poll.h> |
| #include <fcntl.h> |
| #include <getopt.h> |
| #include <sys/ioctl.h> |
| #include <linux/gpio.h> |
| |
| #include "gpio-utils.h" |
| |
| int list_device(const char *device_name) |
| { |
| struct gpiochip_info cinfo; |
| char *chrdev_name; |
| int fd; |
| int ret; |
| |
| ret = asprintf(&chrdev_name, "/dev/%s", device_name); |
| if (ret < 0) |
| return -ENOMEM; |
| |
| fd = open(chrdev_name, 0); |
| if (fd == -1) { |
| ret = -errno; |
| fprintf(stderr, "Failed to open %s\n", chrdev_name); |
| goto free_chrdev_name; |
| } |
| |
| /* Inspect this GPIO chip */ |
| ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo); |
| if (ret == -1) { |
| ret = -errno; |
| fprintf(stderr, "Failed to retrieve GPIO fd\n"); |
| if (close(fd) == -1) |
| perror("Failed to close GPIO character device file"); |
| |
| goto free_chrdev_name; |
| } |
| fprintf(stdout, "GPIO chip: %s, %u GPIO lines\n", |
| cinfo.name, cinfo.lines); |
| |
| if (close(fd) == -1) { |
| ret = -errno; |
| goto free_chrdev_name; |
| } |
| |
| free_chrdev_name: |
| free(chrdev_name); |
| |
| return ret; |
| |
| } |
| |
| void print_usage(void) |
| { |
| fprintf(stderr, "Usage: lsgpio [options]...\n" |
| "List GPIO chips, lines and states\n" |
| " -n <name> List GPIOs on a named device\n" |
| " -? This helptext\n" |
| ); |
| } |
| |
| int main(int argc, char **argv) |
| { |
| const char *device_name; |
| int ret; |
| int c; |
| |
| while ((c = getopt(argc, argv, "n:")) != -1) { |
| switch (c) { |
| case 'n': |
| device_name = optarg; |
| break; |
| case '?': |
| print_usage(); |
| return -1; |
| } |
| } |
| |
| if (device_name) |
| ret = list_device(device_name); |
| else { |
| const struct dirent *ent; |
| DIR *dp; |
| |
| /* List all GPIO devices one at a time */ |
| dp = opendir("/dev"); |
| if (!dp) { |
| ret = -errno; |
| goto error_out; |
| } |
| |
| ret = -ENOENT; |
| while (ent = readdir(dp), ent) { |
| if (check_prefix(ent->d_name, "gpiochip")) { |
| ret = list_device(ent->d_name); |
| if (ret) |
| break; |
| } |
| } |
| |
| ret = 0; |
| if (closedir(dp) == -1) { |
| perror("scanning devices: Failed to close directory"); |
| ret = -errno; |
| } |
| } |
| error_out: |
| return ret; |
| } |