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>

1 files changed, 128 insertions, 0 deletions

diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c
new file mode 100644
index 000000000000..4cfe29da279b
--- /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;
+}