/*-
 * Copyright (c) 2017 Mark Johnston <markj@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/time.h>

#include <machine/cpu.h>

#include <linux/hrtimer.h>

static void
hrtimer_call_handler(void *arg)
{
        struct hrtimer *hrtimer;
        enum hrtimer_restart ret;

        hrtimer = arg;
        ret = hrtimer->function(hrtimer);

        if (ret == HRTIMER_RESTART) {
                callout_schedule_sbt(&hrtimer->callout,
                    nstosbt(hrtimer->expires), nstosbt(hrtimer->precision), 0);
        } else {
                callout_deactivate(&hrtimer->callout);
        }
}

bool
linux_hrtimer_active(struct hrtimer *hrtimer)
{
        bool ret;

        mtx_lock(&hrtimer->mtx);
        ret = callout_active(&hrtimer->callout);
        mtx_unlock(&hrtimer->mtx);

        return (ret);
}

/*
 * Try to cancel active hrtimer.
 * Return 1 if timer was active and cancellation succeeded, 0 if timer was
 * inactive, or -1 if the timer is being serviced and can't be cancelled.
 */
int
linux_hrtimer_try_to_cancel(struct hrtimer *hrtimer)
{
        int ret;

        mtx_lock(&hrtimer->mtx);
        ret = callout_stop(&hrtimer->callout);
        mtx_unlock(&hrtimer->mtx);
        if (ret > 0) {
                return (1);
        } else if (ret < 0) {
                return (0);
        } else {
                return (-1);
        }
}

/*
 * Cancel active hrtimer.
 * Return 1 if timer was active and cancellation succeeded, or 0 otherwise.
 */
int
linux_hrtimer_cancel(struct hrtimer *hrtimer)
{

        return (callout_drain(&hrtimer->callout) > 0);
}

void
linux_hrtimer_init(struct hrtimer *hrtimer)
{

        memset(hrtimer, 0, sizeof(*hrtimer));
        mtx_init(&hrtimer->mtx, "hrtimer", NULL,
            MTX_DEF | MTX_RECURSE | MTX_NOWITNESS);
        callout_init_mtx(&hrtimer->callout, &hrtimer->mtx, 0);
}

void
linux_hrtimer_set_expires(struct hrtimer *hrtimer, ktime_t time)
{
        hrtimer->expires = ktime_to_ns(time);
}

void
linux_hrtimer_start(struct hrtimer *hrtimer, ktime_t time)
{

        linux_hrtimer_start_range_ns(hrtimer, time, 0);
}

void
linux_hrtimer_start_range_ns(struct hrtimer *hrtimer, ktime_t time,
    int64_t nsec)
{

        mtx_lock(&hrtimer->mtx);
        hrtimer->precision = nsec;
        callout_reset_sbt(&hrtimer->callout, nstosbt(ktime_to_ns(time)),
            nstosbt(nsec), hrtimer_call_handler, hrtimer, 0);
        mtx_unlock(&hrtimer->mtx);
}

void
linux_hrtimer_forward_now(struct hrtimer *hrtimer, ktime_t interval)
{

        mtx_lock(&hrtimer->mtx);
        callout_reset_sbt(&hrtimer->callout, nstosbt(ktime_to_ns(interval)),
            nstosbt(hrtimer->precision), hrtimer_call_handler, hrtimer, 0);
        mtx_unlock(&hrtimer->mtx);
}