/*
 * 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':
			/*
			 * Avoid overflow. Do not immediately error, we want to
			 * be able to accurately report on the amount of times
			 * '-o' was given to give an accurate error message
			 */
			if (i < GPIOHANDLES_MAX)
				lines[i] = strtoul(optarg, NULL, 10);

			i++;
			break;
		case '?':
			print_usage();
			return -1;
		}
	}

	if (i >= GPIOHANDLES_MAX) {
		fprintf(stderr,
			"Only %d occurences of '-o' are allowed, %d were found\n",
			GPIOHANDLES_MAX, i + 1);
		return -1;
	}

	nlines = i;

	if (!device_name || !nlines) {
		print_usage();
		return -1;
	}
	return hammer_device(device_name, lines, nlines, loops);
}