LXR linux/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
  25int hammer_device(const char *device_name, unsigned int *lines, int nlines,
  26                  unsigned int loops)
  27{
  28        struct gpiohandle_data data;
  29        char swirr[] = "-\\|/";
  30        int fd;
  31        int ret;
  32        int i, j;
  33        unsigned int iteration = 0;
  34
  35        memset(&data.values, 0, sizeof(data.values));
  36        ret = gpiotools_request_linehandle(device_name, lines, nlines,
  37                                           GPIOHANDLE_REQUEST_OUTPUT, &data,
  38                                           "gpio-hammer");
  39        if (ret < 0)
  40                goto exit_error;
  41        else
  42                fd = ret;
  43
  44        ret = gpiotools_get_values(fd, &data);
  45        if (ret < 0)
  46                goto exit_close_error;
  47
  48        fprintf(stdout, "Hammer lines [");
  49        for (i = 0; i < nlines; i++) {
  50                fprintf(stdout, "%d", lines[i]);
  51                if (i != (nlines - 1))
  52                        fprintf(stdout, ", ");
  53        }
  54        fprintf(stdout, "] on %s, initial states: [", device_name);
  55        for (i = 0; i < nlines; i++) {
  56                fprintf(stdout, "%d", data.values[i]);
  57                if (i != (nlines - 1))
  58                        fprintf(stdout, ", ");
  59        }
  60        fprintf(stdout, "]\n");
  61
  62        /* Hammertime! */
  63        j = 0;
  64        while (1) {
  65                /* Invert all lines so we blink */
  66                for (i = 0; i < nlines; i++)
  67                        data.values[i] = !data.values[i];
  68
  69                ret = gpiotools_set_values(fd, &data);
  70                if (ret < 0)
  71                        goto exit_close_error;
  72
  73                /* Re-read values to get status */
  74                ret = gpiotools_get_values(fd, &data);
  75                if (ret < 0)
  76                        goto exit_close_error;
  77
  78                fprintf(stdout, "[%c] ", swirr[j]);
  79                j++;
  80                if (j == sizeof(swirr)-1)
  81                        j = 0;
  82
  83                fprintf(stdout, "[");
  84                for (i = 0; i < nlines; i++) {
  85                        fprintf(stdout, "%d: %d", lines[i], data.values[i]);
  86                        if (i != (nlines - 1))
  87                                fprintf(stdout, ", ");
  88                }
  89                fprintf(stdout, "]\r");
  90                fflush(stdout);
  91                sleep(1);
  92                iteration++;
  93                if (loops && iteration == loops)
  94                        break;
  95        }
  96        fprintf(stdout, "\n");
  97        ret = 0;
  98
  99exit_close_error:
 100        gpiotools_release_linehandle(fd);
 101exit_error:
 102        return ret;
 103}
 104
 105void print_usage(void)
 106{
 107        fprintf(stderr, "Usage: gpio-hammer [options]...\n"
 108                "Hammer GPIO lines, 0->1->0->1...\n"
 109                "  -n <name>  Hammer GPIOs on a named device (must be stated)\n"
 110                "  -o <n>     Offset[s] to hammer, at least one, several can be stated\n"
 111                " [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
 112                "  -?         This helptext\n"
 113                "\n"
 114                "Example:\n"
 115                "gpio-hammer -n gpiochip0 -o 4\n"
 116        );
 117}
 118
 119int main(int argc, char **argv)
 120{
 121        const char *device_name = NULL;
 122        unsigned int lines[GPIOHANDLES_MAX];
 123        unsigned int loops = 0;
 124        int nlines;
 125        int c;
 126        int i;
 127
 128        i = 0;
 129        while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
 130                switch (c) {
 131                case 'c':
 132                        loops = strtoul(optarg, NULL, 10);
 133                        break;
 134                case 'n':
 135                        device_name = optarg;
 136                        break;
 137                case 'o':
 138                        lines[i] = strtoul(optarg, NULL, 10);
 139                        i++;
 140                        break;
 141                case '?':
 142                        print_usage();
 143                        return -1;
 144                }
 145        }
 146        nlines = i;
 147
 148        if (!device_name || !nlines) {
 149                print_usage();
 150                return -1;
 151        }
 152        return hammer_device(device_name, lines, nlines, loops);
 153}
 154