2 * lsgpio - example on how to list the GPIO lines on a system
4 * Copyright (C) 2015 Linus Walleij
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
11 * lsgpio <-n device-name>
24 #include <sys/ioctl.h>
25 #include <linux/gpio.h>
27 #include "gpio-utils.h"
34 struct gpio_flag flagnames[] = {
37 .mask = GPIOLINE_FLAG_KERNEL,
41 .mask = GPIOLINE_FLAG_IS_OUT,
45 .mask = GPIOLINE_FLAG_ACTIVE_LOW,
49 .mask = GPIOLINE_FLAG_OPEN_DRAIN,
52 .name = "open-source",
53 .mask = GPIOLINE_FLAG_OPEN_SOURCE,
57 void print_flags(unsigned long flags)
62 for (i = 0; i < ARRAY_SIZE(flagnames); i++) {
63 if (flags & flagnames[i].mask) {
66 fprintf(stdout, "%s", flagnames[i].name);
72 int list_device(const char *device_name)
74 struct gpiochip_info cinfo;
80 ret = asprintf(&chrdev_name, "/dev/%s", device_name);
84 fd = open(chrdev_name, 0);
87 fprintf(stderr, "Failed to open %s\n", chrdev_name);
88 goto exit_close_error;
91 /* Inspect this GPIO chip */
92 ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
95 perror("Failed to issue CHIPINFO IOCTL\n");
96 goto exit_close_error;
98 fprintf(stdout, "GPIO chip: %s, \"%s\", %u GPIO lines\n",
99 cinfo.name, cinfo.label, cinfo.lines);
101 /* Loop over the lines and print info */
102 for (i = 0; i < cinfo.lines; i++) {
103 struct gpioline_info linfo;
105 memset(&linfo, 0, sizeof(linfo));
106 linfo.line_offset = i;
108 ret = ioctl(fd, GPIO_GET_LINEINFO_IOCTL, &linfo);
111 perror("Failed to issue LINEINFO IOCTL\n");
112 goto exit_close_error;
114 fprintf(stdout, "\tline %2d:", linfo.line_offset);
116 fprintf(stdout, " \"%s\"", linfo.name);
118 fprintf(stdout, " unnamed");
119 if (linfo.consumer[0])
120 fprintf(stdout, " \"%s\"", linfo.consumer);
122 fprintf(stdout, " unused");
124 fprintf(stdout, " [");
125 print_flags(linfo.flags);
126 fprintf(stdout, "]");
128 fprintf(stdout, "\n");
134 perror("Failed to close GPIO character device file");
139 void print_usage(void)
141 fprintf(stderr, "Usage: lsgpio [options]...\n"
142 "List GPIO chips, lines and states\n"
143 " -n <name> List GPIOs on a named device\n"
144 " -? This helptext\n"
148 int main(int argc, char **argv)
150 const char *device_name = NULL;
154 while ((c = getopt(argc, argv, "n:")) != -1) {
157 device_name = optarg;
166 ret = list_device(device_name);
168 const struct dirent *ent;
171 /* List all GPIO devices one at a time */
172 dp = opendir("/dev");
179 while (ent = readdir(dp), ent) {
180 if (check_prefix(ent->d_name, "gpiochip")) {
181 ret = list_device(ent->d_name);
188 if (closedir(dp) == -1) {
189 perror("scanning devices: Failed to close directory");