tools/gpio/gpio-hammer.c

   1 /*
   2  * gpio-hammer - example swiss army knife to shake GPIO lines on a system
   3  *
   4  * Copyright (C) 2016 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  *      gpio-hammer -n <device-name> -o <offset1> -o <offset2>
  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 int hammer_device(const char *device_name, unsigned int *lines, int nlines,
  28                   unsigned int loops)
  29 {
  30         struct gpiohandle_request req;
  31         struct gpiohandle_data data;
  32         char *chrdev_name;
  33         char swirr[] = "-\\|/";
  34         int fd;
  35         int ret;
  36         int i, j;
  37         unsigned int iteration = 0;
  38
  39         ret = asprintf(&chrdev_name, "/dev/%s", device_name);
  40         if (ret < 0)
  41                 return -ENOMEM;
  42
  43         fd = open(chrdev_name, 0);
  44         if (fd == -1) {
  45                 ret = -errno;
  46                 fprintf(stderr, "Failed to open %s\n", chrdev_name);
  47                 goto exit_close_error;
  48         }
  49
  50         /* Request lines as output */
  51         for (i = 0; i < nlines; i++)
  52                 req.lineoffsets[i] = lines[i];
  53         req.flags = GPIOHANDLE_REQUEST_OUTPUT; /* Request as output */
  54         strcpy(req.consumer_label, "gpio-hammer");
  55         req.lines = nlines;
  56         ret = ioctl(fd, GPIO_GET_LINEHANDLE_IOCTL, &req);
  57         if (ret == -1) {
  58                 ret = -errno;
  59                 fprintf(stderr, "Failed to issue GET LINEHANDLE "
  60                         "IOCTL (%d)\n",
  61                         ret);
  62                 goto exit_close_error;
  63         }
  64
  65         /* Read initial states */
  66         ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
  67         if (ret == -1) {
  68                 ret = -errno;
  69                 fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
  70                         "VALUES IOCTL (%d)\n",
  71                         ret);
  72                 goto exit_close_error;
  73         }
  74         fprintf(stdout, "Hammer lines [");
  75         for (i = 0; i < nlines; i++) {
  76                 fprintf(stdout, "%d", lines[i]);
  77                 if (i != (nlines - 1))
  78                         fprintf(stdout, ", ");
  79         }
  80         fprintf(stdout, "] on %s, initial states: [", device_name);
  81         for (i = 0; i < nlines; i++) {
  82                 fprintf(stdout, "%d", data.values[i]);
  83                 if (i != (nlines - 1))
  84                         fprintf(stdout, ", ");
  85         }
  86         fprintf(stdout, "]\n");
  87
  88         /* Hammertime! */
  89         j = 0;
  90         while (1) {
  91                 /* Invert all lines so we blink */
  92                 for (i = 0; i < nlines; i++)
  93                         data.values[i] = !data.values[i];
  94
  95                 ret = ioctl(req.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &data);
  96                 if (ret == -1) {
  97                         ret = -errno;
  98                         fprintf(stderr, "Failed to issue GPIOHANDLE SET LINE "
  99                                 "VALUES IOCTL (%d)\n",
 100                                 ret);
 101                         goto exit_close_error;
 102                 }
 103                 /* Re-read values to get status */
 104                 ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
 105                 if (ret == -1) {
 106                         ret = -errno;
 107                         fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
 108                                 "VALUES IOCTL (%d)\n",
 109                                 ret);
 110                         goto exit_close_error;
 111                 }
 112
 113                 fprintf(stdout, "[%c] ", swirr[j]);
 114                 j++;
 115                 if (j == sizeof(swirr)-1)
 116                         j = 0;
 117
 118                 fprintf(stdout, "[");
 119                 for (i = 0; i < nlines; i++) {
 120                         fprintf(stdout, "%d: %d", lines[i], data.values[i]);
 121                         if (i != (nlines - 1))
 122                                 fprintf(stdout, ", ");
 123                 }
 124                 fprintf(stdout, "]\r");
 125                 fflush(stdout);
 126                 sleep(1);
 127                 iteration++;
 128                 if (loops && iteration == loops)
 129                         break;
 130         }
 131         fprintf(stdout, "\n");
 132         ret = 0;
 133
 134 exit_close_error:
 135         if (close(fd) == -1)
 136                 perror("Failed to close GPIO character device file");
 137         free(chrdev_name);
 138         return ret;
 139 }
 140
 141 void print_usage(void)
 142 {
 143         fprintf(stderr, "Usage: gpio-hammer [options]...\n"
 144                 "Hammer GPIO lines, 0->1->0->1...\n"
 145                 "  -n <name>  Hammer GPIOs on a named device (must be stated)\n"
 146                 "  -o <n>     Offset[s] to hammer, at least one, several can be stated\n"
 147                 " [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
 148                 "  -?         This helptext\n"
 149                 "\n"
 150                 "Example:\n"
 151                 "gpio-hammer -n gpiochip0 -o 4\n"
 152         );
 153 }
 154
 155 int main(int argc, char **argv)
 156 {
 157         const char *device_name = NULL;
 158         unsigned int lines[GPIOHANDLES_MAX];
 159         unsigned int loops = 0;
 160         int nlines;
 161         int c;
 162         int i;
 163
 164         i = 0;
 165         while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
 166                 switch (c) {
 167                 case 'c':
 168                         loops = strtoul(optarg, NULL, 10);
 169                         break;
 170                 case 'n':
 171                         device_name = optarg;
 172                         break;
 173                 case 'o':
 174                         lines[i] = strtoul(optarg, NULL, 10);
 175                         i++;
 176                         break;
 177                 case '?':
 178                         print_usage();
 179                         return -1;
 180                 }
 181         }
 182         nlines = i;
 183
 184         if (!device_name || !nlines) {
 185                 print_usage();
 186                 return -1;
 187         }
 188         return hammer_device(device_name, lines, nlines, loops);
 189 }