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 #include "gpio-utils.h"
  27
  28 int hammer_device(const char *device_name, unsigned int *lines, int nlines,
  29                   unsigned int loops)
  30 {
  31         struct gpiohandle_data data;
  32         char swirr[] = "-\\|/";
  33         int fd;
  34         int ret;
  35         int i, j;
  36         unsigned int iteration = 0;
  37
  38         memset(&data.values, 0, sizeof(data.values));
  39         ret = gpiotools_request_linehandle(device_name, lines, nlines,
  40                                            GPIOHANDLE_REQUEST_OUTPUT, &data,
  41                                            "gpio-hammer");
  42         if (ret < 0)
  43                 goto exit_error;
  44         else
  45                 fd = ret;
  46
  47         ret = gpiotools_get_values(fd, &data);
  48         if (ret < 0)
  49                 goto exit_close_error;
  50
  51         fprintf(stdout, "Hammer lines [");
  52         for (i = 0; i < nlines; i++) {
  53                 fprintf(stdout, "%d", lines[i]);
  54                 if (i != (nlines - 1))
  55                         fprintf(stdout, ", ");
  56         }
  57         fprintf(stdout, "] on %s, initial states: [", device_name);
  58         for (i = 0; i < nlines; i++) {
  59                 fprintf(stdout, "%d", data.values[i]);
  60                 if (i != (nlines - 1))
  61                         fprintf(stdout, ", ");
  62         }
  63         fprintf(stdout, "]\n");
  64
  65         /* Hammertime! */
  66         j = 0;
  67         while (1) {
  68                 /* Invert all lines so we blink */
  69                 for (i = 0; i < nlines; i++)
  70                         data.values[i] = !data.values[i];
  71
  72                 ret = gpiotools_set_values(fd, &data);
  73                 if (ret < 0)
  74                         goto exit_close_error;
  75
  76                 /* Re-read values to get status */
  77                 ret = gpiotools_get_values(fd, &data);
  78                 if (ret < 0)
  79                         goto exit_close_error;
  80
  81                 fprintf(stdout, "[%c] ", swirr[j]);
  82                 j++;
  83                 if (j == sizeof(swirr)-1)
  84                         j = 0;
  85
  86                 fprintf(stdout, "[");
  87                 for (i = 0; i < nlines; i++) {
  88                         fprintf(stdout, "%d: %d", lines[i], data.values[i]);
  89                         if (i != (nlines - 1))
  90                                 fprintf(stdout, ", ");
  91                 }
  92                 fprintf(stdout, "]\r");
  93                 fflush(stdout);
  94                 sleep(1);
  95                 iteration++;
  96                 if (loops && iteration == loops)
  97                         break;
  98         }
  99         fprintf(stdout, "\n");
 100         ret = 0;
 101
 102 exit_close_error:
 103         gpiotools_release_linehandle(fd);
 104 exit_error:
 105         return ret;
 106 }
 107
 108 void print_usage(void)
 109 {
 110         fprintf(stderr, "Usage: gpio-hammer [options]...\n"
 111                 "Hammer GPIO lines, 0->1->0->1...\n"
 112                 "  -n <name>  Hammer GPIOs on a named device (must be stated)\n"
 113                 "  -o <n>     Offset[s] to hammer, at least one, several can be stated\n"
 114                 " [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
 115                 "  -?         This helptext\n"
 116                 "\n"
 117                 "Example:\n"
 118                 "gpio-hammer -n gpiochip0 -o 4\n"
 119         );
 120 }
 121
 122 int main(int argc, char **argv)
 123 {
 124         const char *device_name = NULL;
 125         unsigned int lines[GPIOHANDLES_MAX];
 126         unsigned int loops = 0;
 127         int nlines;
 128         int c;
 129         int i;
 130
 131         i = 0;
 132         while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
 133                 switch (c) {
 134                 case 'c':
 135                         loops = strtoul(optarg, NULL, 10);
 136                         break;
 137                 case 'n':
 138                         device_name = optarg;
 139                         break;
 140                 case 'o':
 141                         /*
 142                          * Avoid overflow. Do not immediately error, we want to
 143                          * be able to accurately report on the amount of times
 144                          * '-o' was given to give an accurate error message
 145                          */
 146                         if (i < GPIOHANDLES_MAX)
 147                                 lines[i] = strtoul(optarg, NULL, 10);
 148
 149                         i++;
 150                         break;
 151                 case '?':
 152                         print_usage();
 153                         return -1;
 154                 }
 155         }
 156
 157         if (i >= GPIOHANDLES_MAX) {
 158                 fprintf(stderr,
 159                         "Only %d occurences of '-o' are allowed, %d were found\n",
 160                         GPIOHANDLES_MAX, i + 1);
 161                 return -1;
 162         }
 163
 164         nlines = i;
 165
 166         if (!device_name || !nlines) {
 167                 print_usage();
 168                 return -1;
 169         }
 170         return hammer_device(device_name, lines, nlines, loops);
 171 }