tools/gpio/lsgpio.c

   1 /*
   2  * lsgpio - example on how to list the GPIO lines on a system
   3  *
   4  * Copyright (C) 2015 Linus Walleij
   5  *
   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.
   9  *
  10  * Usage:
  11  *      lsgpio <-n device-name>
  12  */
  13
  14 #include <unistd.h>
  15 #include <stdlib.h>
  16 #include <stdbool.h>
  17 #include <stdio.h>
  18 #include <dirent.h>
  19 #include <errno.h>
  20 #include <string.h>
  21 #include <poll.h>
  22 #include <fcntl.h>
  23 #include <getopt.h>
  24 #include <sys/ioctl.h>
  25 #include <linux/gpio.h>
  26
  27 #include "gpio-utils.h"
  28
  29 struct gpio_flag {
  30         char *name;
  31         unsigned long mask;
  32 };
  33
  34 struct gpio_flag flagnames[] = {
  35         {
  36                 .name = "kernel",
  37                 .mask = GPIOLINE_FLAG_KERNEL,
  38         },
  39         {
  40                 .name = "output",
  41                 .mask = GPIOLINE_FLAG_IS_OUT,
  42         },
  43         {
  44                 .name = "active-low",
  45                 .mask = GPIOLINE_FLAG_ACTIVE_LOW,
  46         },
  47         {
  48                 .name = "open-drain",
  49                 .mask = GPIOLINE_FLAG_OPEN_DRAIN,
  50         },
  51         {
  52                 .name = "open-source",
  53                 .mask = GPIOLINE_FLAG_OPEN_SOURCE,
  54         },
  55 };
  56
  57 void print_flags(unsigned long flags)
  58 {
  59         int i;
  60         int printed = 0;
  61
  62         for (i = 0; i < ARRAY_SIZE(flagnames); i++) {
  63                 if (flags & flagnames[i].mask) {
  64                         if (printed)
  65                                 fprintf(stdout, " ");
  66                         fprintf(stdout, "%s", flagnames[i].name);
  67                         printed++;
  68                 }
  69         }
  70 }
  71
  72 int list_device(const char *device_name)
  73 {
  74         struct gpiochip_info cinfo;
  75         char *chrdev_name;
  76         int fd;
  77         int ret;
  78         int i;
  79
  80         ret = asprintf(&chrdev_name, "/dev/%s", device_name);
  81         if (ret < 0)
  82                 return -ENOMEM;
  83
  84         fd = open(chrdev_name, 0);
  85         if (fd == -1) {
  86                 ret = -errno;
  87                 fprintf(stderr, "Failed to open %s\n", chrdev_name);
  88                 goto exit_close_error;
  89         }
  90
  91         /* Inspect this GPIO chip */
  92         ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &cinfo);
  93         if (ret == -1) {
  94                 ret = -errno;
  95                 perror("Failed to issue CHIPINFO IOCTL\n");
  96                 goto exit_close_error;
  97         }
  98         fprintf(stdout, "GPIO chip: %s, \"%s\", %u GPIO lines\n",
  99                 cinfo.name, cinfo.label, cinfo.lines);
 100
 101         /* Loop over the lines and print info */
 102         for (i = 0; i < cinfo.lines; i++) {
 103                 struct gpioline_info linfo;
 104
 105                 memset(&linfo, 0, sizeof(linfo));
 106                 linfo.line_offset = i;
 107
 108                 ret = ioctl(fd, GPIO_GET_LINEINFO_IOCTL, &linfo);
 109                 if (ret == -1) {
 110                         ret = -errno;
 111                         perror("Failed to issue LINEINFO IOCTL\n");
 112                         goto exit_close_error;
 113                 }
 114                 fprintf(stdout, "\tline %2d:", linfo.line_offset);
 115                 if (linfo.name[0])
 116                         fprintf(stdout, " \"%s\"", linfo.name);
 117                 else
 118                         fprintf(stdout, " unnamed");
 119                 if (linfo.consumer[0])
 120                         fprintf(stdout, " \"%s\"", linfo.consumer);
 121                 else
 122                         fprintf(stdout, " unused");
 123                 if (linfo.flags) {
 124                         fprintf(stdout, " [");
 125                         print_flags(linfo.flags);
 126                         fprintf(stdout, "]");
 127                 }
 128                 fprintf(stdout, "\n");
 129
 130         }
 131
 132 exit_close_error:
 133         if (close(fd) == -1)
 134                 perror("Failed to close GPIO character device file");
 135         free(chrdev_name);
 136         return ret;
 137 }
 138
 139 void print_usage(void)
 140 {
 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"
 145         );
 146 }
 147
 148 int main(int argc, char **argv)
 149 {
 150         const char *device_name = NULL;
 151         int ret;
 152         int c;
 153
 154         while ((c = getopt(argc, argv, "n:")) != -1) {
 155                 switch (c) {
 156                 case 'n':
 157                         device_name = optarg;
 158                         break;
 159                 case '?':
 160                         print_usage();
 161                         return -1;
 162                 }
 163         }
 164
 165         if (device_name)
 166                 ret = list_device(device_name);
 167         else {
 168                 const struct dirent *ent;
 169                 DIR *dp;
 170
 171                 /* List all GPIO devices one at a time */
 172                 dp = opendir("/dev");
 173                 if (!dp) {
 174                         ret = -errno;
 175                         goto error_out;
 176                 }
 177
 178                 ret = -ENOENT;
 179                 while (ent = readdir(dp), ent) {
 180                         if (check_prefix(ent->d_name, "gpiochip")) {
 181                                 ret = list_device(ent->d_name);
 182                                 if (ret)
 183                                         break;
 184                         }
 185                 }
 186
 187                 ret = 0;
 188                 if (closedir(dp) == -1) {
 189                         perror("scanning devices: Failed to close directory");
 190                         ret = -errno;
 191                 }
 192         }
 193 error_out:
 194         return ret;
 195 }