tools/gpio/gpio-hammer.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * gpio-hammer - example swiss army knife to shake GPIO lines on a system
   4  *
   5  * Copyright (C) 2016 Linus Walleij
   6  *
   7  * Usage:
   8  *      gpio-hammer -n <device-name> -o <offset1> -o <offset2>
   9  */
  10
  11 #include <unistd.h>
  12 #include <stdlib.h>
  13 #include <stdbool.h>
  14 #include <stdio.h>
  15 #include <dirent.h>
  16 #include <errno.h>
  17 #include <string.h>
  18 #include <poll.h>
  19 #include <fcntl.h>
  20 #include <getopt.h>
  21 #include <sys/ioctl.h>
  22 #include <linux/gpio.h>
  23 #include "gpio-utils.h"
  24
  25 int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
  26                   unsigned int loops)
  27 {
  28         struct gpio_v2_line_values values;
  29         struct gpio_v2_line_config config;
  30         char swirr[] = "-\\|/";
  31         int fd;
  32         int ret;
  33         int i, j;
  34         unsigned int iteration = 0;
  35
  36         memset(&config, 0, sizeof(config));
  37         config.flags = GPIO_V2_LINE_FLAG_OUTPUT;
  38
  39         ret = gpiotools_request_line(device_name, lines, num_lines,
  40                                      &config, "gpio-hammer");
  41         if (ret < 0)
  42                 goto exit_error;
  43         else
  44                 fd = ret;
  45
  46         values.mask = 0;
  47         values.bits = 0;
  48         for (i = 0; i < num_lines; i++)
  49                 gpiotools_set_bit(&values.mask, i);
  50
  51         ret = gpiotools_get_values(fd, &values);
  52         if (ret < 0)
  53                 goto exit_close_error;
  54
  55         fprintf(stdout, "Hammer lines [");
  56         for (i = 0; i < num_lines; i++) {
  57                 fprintf(stdout, "%d", lines[i]);
  58                 if (i != (num_lines - 1))
  59                         fprintf(stdout, ", ");
  60         }
  61         fprintf(stdout, "] on %s, initial states: [", device_name);
  62         for (i = 0; i < num_lines; i++) {
  63                 fprintf(stdout, "%d", gpiotools_test_bit(values.bits, i));
  64                 if (i != (num_lines - 1))
  65                         fprintf(stdout, ", ");
  66         }
  67         fprintf(stdout, "]\n");
  68
  69         /* Hammertime! */
  70         j = 0;
  71         while (1) {
  72                 /* Invert all lines so we blink */
  73                 for (i = 0; i < num_lines; i++)
  74                         gpiotools_change_bit(&values.bits, i);
  75
  76                 ret = gpiotools_set_values(fd, &values);
  77                 if (ret < 0)
  78                         goto exit_close_error;
  79
  80                 /* Re-read values to get status */
  81                 ret = gpiotools_get_values(fd, &values);
  82                 if (ret < 0)
  83                         goto exit_close_error;
  84
  85                 fprintf(stdout, "[%c] ", swirr[j]);
  86                 j++;
  87                 if (j == sizeof(swirr) - 1)
  88                         j = 0;
  89
  90                 fprintf(stdout, "[");
  91                 for (i = 0; i < num_lines; i++) {
  92                         fprintf(stdout, "%d: %d", lines[i],
  93                                 gpiotools_test_bit(values.bits, i));
  94                         if (i != (num_lines - 1))
  95                                 fprintf(stdout, ", ");
  96                 }
  97                 fprintf(stdout, "]\r");
  98                 fflush(stdout);
  99                 sleep(1);
 100                 iteration++;
 101                 if (loops && iteration == loops)
 102                         break;
 103         }
 104         fprintf(stdout, "\n");
 105         ret = 0;
 106
 107 exit_close_error:
 108         gpiotools_release_line(fd);
 109 exit_error:
 110         return ret;
 111 }
 112
 113 void print_usage(void)
 114 {
 115         fprintf(stderr, "Usage: gpio-hammer [options]...\n"
 116                 "Hammer GPIO lines, 0->1->0->1...\n"
 117                 "  -n <name>  Hammer GPIOs on a named device (must be stated)\n"
 118                 "  -o <n>     Offset[s] to hammer, at least one, several can be stated\n"
 119                 " [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
 120                 "  -?         This helptext\n"
 121                 "\n"
 122                 "Example:\n"
 123                 "gpio-hammer -n gpiochip0 -o 4\n"
 124         );
 125 }
 126
 127 int main(int argc, char **argv)
 128 {
 129         const char *device_name = NULL;
 130         unsigned int lines[GPIOHANDLES_MAX];
 131         unsigned int loops = 0;
 132         int num_lines;
 133         int c;
 134         int i;
 135
 136         i = 0;
 137         while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
 138                 switch (c) {
 139                 case 'c':
 140                         loops = strtoul(optarg, NULL, 10);
 141                         break;
 142                 case 'n':
 143                         device_name = optarg;
 144                         break;
 145                 case 'o':
 146                         /*
 147                          * Avoid overflow. Do not immediately error, we want to
 148                          * be able to accurately report on the amount of times
 149                          * '-o' was given to give an accurate error message
 150                          */
 151                         if (i < GPIOHANDLES_MAX)
 152                                 lines[i] = strtoul(optarg, NULL, 10);
 153
 154                         i++;
 155                         break;
 156                 case '?':
 157                         print_usage();
 158                         return -1;
 159                 }
 160         }
 161
 162         if (i >= GPIOHANDLES_MAX) {
 163                 fprintf(stderr,
 164                         "Only %d occurrences of '-o' are allowed, %d were found\n",
 165                         GPIOHANDLES_MAX, i + 1);
 166                 return -1;
 167         }
 168
 169         num_lines = i;
 170
 171         if (!device_name || !num_lines) {
 172                 print_usage();
 173                 return -1;
 174         }
 175         return hammer_device(device_name, lines, num_lines, loops);
 176 }