/*
* gpio-hammer - example swiss army knife to shake GPIO lines on a system
*
* Copyright (C) 2016 Linus Walleij
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* Usage:
* gpio-hammer -n <device-name> -o <offset1> -o <offset2>
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include <dirent.h>
#include <errno.h>
#include <string.h>
#include <poll.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/ioctl.h>
#include <linux/gpio.h>
int hammer_device(const char *device_name, unsigned int *lines, int nlines,
unsigned int loops)
{
struct gpiohandle_request req;
struct gpiohandle_data data;
char *chrdev_name;
char swirr[] = "-\\|/";
int fd;
int ret;
int i, j;
unsigned int iteration = 0;
ret = asprintf(&chrdev_name, "/dev/%s", device_name);
if (ret < 0)
return -ENOMEM;
fd = open(chrdev_name, 0);
if (fd == -1) {
ret = -errno;
fprintf(stderr, "Failed to open %s\n", chrdev_name);
goto exit_close_error;
}
/* Request lines as output */
for (i = 0; i < nlines; i++)
req.lineoffsets[i] = lines[i];
req.flags = GPIOHANDLE_REQUEST_OUTPUT; /* Request as output */
strcpy(req.consumer_label, "gpio-hammer");
req.lines = nlines;
ret = ioctl(fd, GPIO_GET_LINEHANDLE_IOCTL, &req);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to issue GET LINEHANDLE "
"IOCTL (%d)\n",
ret);
goto exit_close_error;
}
/* Read initial states */
ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
"VALUES IOCTL (%d)\n",
ret);
goto exit_close_error;
}
fprintf(stdout, "Hammer lines [");
for (i = 0; i < nlines; i++) {
fprintf(stdout, "%d", lines[i]);
if (i != (nlines - 1))
fprintf(stdout, ", ");
}
fprintf(stdout, "] on %s, initial states: [", device_name);
for (i = 0; i < nlines; i++) {
fprintf(stdout, "%d", data.values[i]);
if (i != (nlines - 1))
fprintf(stdout, ", ");
}
fprintf(stdout, "]\n");
/* Hammertime! */
j = 0;
while (1) {
/* Invert all lines so we blink */
for (i = 0; i < nlines; i++)
data.values[i] = !data.values[i];
ret = ioctl(req.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &data);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to issue GPIOHANDLE SET LINE "
"VALUES IOCTL (%d)\n",
ret);
goto exit_close_error;
}
/* Re-read values to get status */
ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
if (ret == -1) {
ret = -errno;
fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
"VALUES IOCTL (%d)\n",
ret);
goto exit_close_error;
}
fprintf(stdout, "[%c] ", swirr[j]);
j++;
if (j == sizeof(swirr)-1)
j = 0;
fprintf(stdout, "[");
for (i = 0; i < nlines; i++) {
fprintf(stdout, "%d: %d", lines[i], data.values[i]);
if (i != (nlines - 1))
fprintf(stdout, ", ");
}
fprintf(stdout, "]\r");
fflush(stdout);
sleep(1);
iteration++;
if (loops && iteration == loops)
break;
}
fprintf(stdout, "\n");
ret = 0;
exit_close_error:
if (close(fd) == -1)
perror("Failed to close GPIO character device file");
free(chrdev_name);
return ret;
}
void print_usage(void)
{
fprintf(stderr, "Usage: gpio-hammer [options]...\n"
"Hammer GPIO lines, 0->1->0->1...\n"
" -n <name> Hammer GPIOs on a named device (must be stated)\n"
" -o <n> Offset[s] to hammer, at least one, several can be stated\n"
" [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
" -? This helptext\n"
"\n"
"Example:\n"
"gpio-hammer -n gpiochip0 -o 4\n"
);
}
int main(int argc, char **argv)
{
const char *device_name = NULL;
unsigned int lines[GPIOHANDLES_MAX];
unsigned int loops = 0;
int nlines;
int c;
int i;
i = 0;
while ((c = getopt(argc, argv, "c:n:o:?")) != -1) {
switch (c) {
case 'c':
loops = strtoul(optarg, NULL, 10);
break;
case 'n':
device_name = optarg;
break;
case 'o':
lines[i] = strtoul(optarg, NULL, 10);
i++;
break;
case '?':
print_usage();
return -1;
}
}
nlines = i;
if (!device_name || !nlines) {
print_usage();
return -1;
}
return hammer_device(device_name, lines, nlines, loops);
}
