/*
 * 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);
}