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6d591c46bc
This creates GPIO tools under tools/gpio/* and adds a single example program to list the GPIOs on a system. When proper devices are created it provides this minimal output: Cc: Johan Hovold <johan@kernel.org> Cc: Michael Welling <mwelling@ieee.org> Cc: Markus Pargmann <mpa@pengutronix.de> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
129 lines
2.4 KiB
C
129 lines
2.4 KiB
C
/*
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* lsgpio - example on how to list the GPIO lines on a system
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*
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* Copyright (C) 2015 Linus Walleij
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* Usage:
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* lsgpio <-n device-name>
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*/
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <dirent.h>
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#include <errno.h>
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#include <string.h>
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#include <poll.h>
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#include <fcntl.h>
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#include <getopt.h>
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#include <sys/ioctl.h>
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#include <linux/gpio.h>
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#include "gpio-utils.h"
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int list_device(const char *device_name)
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{
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struct gpiochip_info cinfo;
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char *chrdev_name;
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int fd;
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int ret;
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ret = asprintf(&chrdev_name, "/dev/%s", device_name);
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if (ret < 0)
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return -ENOMEM;
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fd = open(chrdev_name, 0);
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if (fd == -1) {
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ret = -errno;
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fprintf(stderr, "Failed to open %s\n", chrdev_name);
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goto free_chrdev_name;
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}
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/* Inspect this GPIO chip */
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ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
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if (ret == -1) {
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ret = -errno;
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fprintf(stderr, "Failed to retrieve GPIO fd\n");
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if (close(fd) == -1)
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perror("Failed to close GPIO character device file");
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goto free_chrdev_name;
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}
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fprintf(stdout, "GPIO chip: %s, %u GPIO lines\n",
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cinfo.name, cinfo.lines);
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if (close(fd) == -1) {
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ret = -errno;
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goto free_chrdev_name;
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}
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free_chrdev_name:
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free(chrdev_name);
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return ret;
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}
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void print_usage(void)
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{
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fprintf(stderr, "Usage: lsgpio [options]...\n"
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"List GPIO chips, lines and states\n"
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" -n <name> List GPIOs on a named device\n"
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" -? This helptext\n"
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);
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}
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int main(int argc, char **argv)
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{
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const char *device_name;
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int ret;
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int c;
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while ((c = getopt(argc, argv, "n:")) != -1) {
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switch (c) {
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case 'n':
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device_name = optarg;
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break;
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case '?':
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print_usage();
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return -1;
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}
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}
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if (device_name)
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ret = list_device(device_name);
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else {
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const struct dirent *ent;
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DIR *dp;
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/* List all GPIO devices one at a time */
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dp = opendir("/dev");
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if (!dp) {
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ret = -errno;
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goto error_out;
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}
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ret = -ENOENT;
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while (ent = readdir(dp), ent) {
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if (check_prefix(ent->d_name, "gpiochip")) {
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ret = list_device(ent->d_name);
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if (ret)
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break;
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}
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}
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ret = 0;
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if (closedir(dp) == -1) {
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perror("scanning devices: Failed to close directory");
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ret = -errno;
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}
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}
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error_out:
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return ret;
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}
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