diff options
author | Linus Walleij <linus.walleij@linaro.org> | 2015-10-21 13:45:54 (GMT) |
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committer | Linus Walleij <linus.walleij@linaro.org> | 2016-02-09 10:09:48 (GMT) |
commit | 6d591c46bce037696d173bd5c8461b2b4bb680ad (patch) | |
tree | 5b7d5e0004de27d1451f38e3e1ddf99837e5d615 /tools/gpio/lsgpio.c | |
parent | 3c702e9987e261042a07e43460a8148be254412e (diff) | |
download | linux-6d591c46bce037696d173bd5c8461b2b4bb680ad.tar.xz |
tools/gpio: create GPIO tools
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>
Diffstat (limited to 'tools/gpio/lsgpio.c')
-rw-r--r-- | tools/gpio/lsgpio.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c new file mode 100644 index 0000000..4cfe29d --- /dev/null +++ b/tools/gpio/lsgpio.c @@ -0,0 +1,128 @@ +/* + * 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; +} |