/*
 * Copyright 2012 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Ben Skeggs
 */
#include "priv.h"

s64
nvkm_timer_wait_test(struct nvkm_timer_wait *wait)
{
        struct nvkm_subdev *subdev = &wait->tmr->subdev;
        u64 time = nvkm_timer_read(wait->tmr);

        if (wait->reads == 0) {
                wait->time0 = time;
                wait->time1 = time;
        }

        if (wait->time1 == time) {
                if (wait->reads++ == 16) {
                        nvkm_fatal(subdev, "stalled at %016llx\n", time);
                        return -ETIMEDOUT;
                }
        } else {
                wait->time1 = time;
                wait->reads = 1;
        }

        if (wait->time1 - wait->time0 > wait->limit)
                return -ETIMEDOUT;

        return wait->time1 - wait->time0;
}

void
nvkm_timer_wait_init(struct nvkm_device *device, u64 nsec,
                     struct nvkm_timer_wait *wait)
{
        wait->tmr = device->timer;
        wait->limit = nsec;
        wait->reads = 0;
}

u64
nvkm_timer_read(struct nvkm_timer *tmr)
{
        return tmr->func->read(tmr);
}

void
nvkm_timer_alarm_trigger(struct nvkm_timer *tmr)
{
        struct nvkm_alarm *alarm, *atemp;
        unsigned long flags;
        LIST_HEAD(exec);

        /* Process pending alarms. */
        spin_lock_irqsave(&tmr->lock, flags);
        list_for_each_entry_safe(alarm, atemp, &tmr->alarms, head) {
                /* Have we hit the earliest alarm that hasn't gone off? */
                if (alarm->timestamp > nvkm_timer_read(tmr)) {
                        /* Schedule it.  If we didn't race, we're done. */
                        tmr->func->alarm_init(tmr, alarm->timestamp);
                        if (alarm->timestamp > nvkm_timer_read(tmr))
                                break;
                }

                /* Move to completed list.  We'll drop the lock before
                 * executing the callback so it can reschedule itself.
                 */
                list_del_init(&alarm->head);
                list_add(&alarm->exec, &exec);
        }

        /* Shut down interrupt if no more pending alarms. */
        if (list_empty(&tmr->alarms))
                tmr->func->alarm_fini(tmr);
        spin_unlock_irqrestore(&tmr->lock, flags);

        /* Execute completed callbacks. */
        list_for_each_entry_safe(alarm, atemp, &exec, exec) {
                list_del(&alarm->exec);
                alarm->func(alarm);
        }
}

void
nvkm_timer_alarm(struct nvkm_timer *tmr, u32 nsec, struct nvkm_alarm *alarm)
{
        struct nvkm_alarm *list;
        unsigned long flags;

        /* Remove alarm from pending list.
         *
         * This both protects against the corruption of the list,
         * and implements alarm rescheduling/cancellation.
         */
        spin_lock_irqsave(&tmr->lock, flags);
        list_del_init(&alarm->head);

        if (nsec) {
                /* Insert into pending list, ordered earliest to latest. */
                alarm->timestamp = nvkm_timer_read(tmr) + nsec;
                list_for_each_entry(list, &tmr->alarms, head) {
                        if (list->timestamp > alarm->timestamp)
                                break;
                }

                list_add_tail(&alarm->head, &list->head);

                /* Update HW if this is now the earliest alarm. */
                list = list_first_entry(&tmr->alarms, typeof(*list), head);
                if (list == alarm) {
                        tmr->func->alarm_init(tmr, alarm->timestamp);
                        /* This shouldn't happen if callers aren't stupid.
                         *
                         * Worst case scenario is that it'll take roughly
                         * 4 seconds for the next alarm to trigger.
                         */
                        WARN_ON(alarm->timestamp <= nvkm_timer_read(tmr));
                }
        }
        spin_unlock_irqrestore(&tmr->lock, flags);
}

static void
nvkm_timer_intr(struct nvkm_subdev *subdev)
{
        struct nvkm_timer *tmr = nvkm_timer(subdev);
        tmr->func->intr(tmr);
}

static int
nvkm_timer_fini(struct nvkm_subdev *subdev, enum nvkm_suspend_state suspend)
{
        struct nvkm_timer *tmr = nvkm_timer(subdev);
        tmr->func->alarm_fini(tmr);
        return 0;
}

static int
nvkm_timer_init(struct nvkm_subdev *subdev)
{
        struct nvkm_timer *tmr = nvkm_timer(subdev);
        if (tmr->func->init)
                tmr->func->init(tmr);
        tmr->func->time(tmr, ktime_to_ns(ktime_get()));
        nvkm_timer_alarm_trigger(tmr);
        return 0;
}

static void *
nvkm_timer_dtor(struct nvkm_subdev *subdev)
{
        return nvkm_timer(subdev);
}

static const struct nvkm_subdev_func
nvkm_timer = {
        .dtor = nvkm_timer_dtor,
        .init = nvkm_timer_init,
        .fini = nvkm_timer_fini,
        .intr = nvkm_timer_intr,
};

int
nvkm_timer_new_(const struct nvkm_timer_func *func, struct nvkm_device *device,
                enum nvkm_subdev_type type, int inst, struct nvkm_timer **ptmr)
{
        struct nvkm_timer *tmr;

        if (!(tmr = *ptmr = kzalloc_obj(*tmr)))
                return -ENOMEM;

        nvkm_subdev_ctor(&nvkm_timer, device, type, inst, &tmr->subdev);
        tmr->func = func;
        INIT_LIST_HEAD(&tmr->alarms);
        spin_lock_init(&tmr->lock);
        return 0;
}