/*
 * Copyright (C) 2007 Ben Skeggs.
 * All Rights Reserved.
 *
 * 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 (including the
 * next paragraph) 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 OWNER(S) AND/OR ITS SUPPLIERS 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.
 *
 */

#include <drm/drmP.h>

#include <linux/ktime.h>
#include <linux/hrtimer.h>
#include <trace/events/fence.h>

#include <nvif/notify.h>
#include <nvif/event.h>

#include "nouveau_drm.h"
#include "nouveau_dma.h"
#include "nouveau_fence.h"

static const struct fence_ops nouveau_fence_ops_uevent;
static const struct fence_ops nouveau_fence_ops_legacy;

static inline struct nouveau_fence *
from_fence(struct fence *fence)
{
        return container_of(fence, struct nouveau_fence, base);
}

static inline struct nouveau_fence_chan *
nouveau_fctx(struct nouveau_fence *fence)
{
        return container_of(fence->base.lock, struct nouveau_fence_chan, lock);
}

static int
nouveau_fence_signal(struct nouveau_fence *fence)
{
        int drop = 0;

        fence_signal_locked(&fence->base);
        list_del(&fence->head);
        rcu_assign_pointer(fence->channel, NULL);

        if (test_bit(FENCE_FLAG_USER_BITS, &fence->base.flags)) {
                struct nouveau_fence_chan *fctx = nouveau_fctx(fence);

                if (!--fctx->notify_ref)
                        drop = 1;
        }

        fence_put(&fence->base);
        return drop;
}

static struct nouveau_fence *
nouveau_local_fence(struct fence *fence, struct nouveau_drm *drm) {
        struct nouveau_fence_priv *priv = (void*)drm->fence;

        if (fence->ops != &nouveau_fence_ops_legacy &&
            fence->ops != &nouveau_fence_ops_uevent)
                return NULL;

        if (fence->context < priv->context_base ||
            fence->context >= priv->context_base + priv->contexts)
                return NULL;

        return from_fence(fence);
}

void
nouveau_fence_context_del(struct nouveau_fence_chan *fctx)
{
        struct nouveau_fence *fence;

        spin_lock_irq(&fctx->lock);
        while (!list_empty(&fctx->pending)) {
                fence = list_entry(fctx->pending.next, typeof(*fence), head);

                if (nouveau_fence_signal(fence))
                        nvif_notify_put(&fctx->notify);
        }
        spin_unlock_irq(&fctx->lock);

        nvif_notify_fini(&fctx->notify);
        fctx->dead = 1;

        /*
         * Ensure that all accesses to fence->channel complete before freeing
         * the channel.
         */
        synchronize_rcu();
}

static void
nouveau_fence_context_put(struct kref *fence_ref)
{
        kfree(container_of(fence_ref, struct nouveau_fence_chan, fence_ref));
}

void
nouveau_fence_context_free(struct nouveau_fence_chan *fctx)
{
        kref_put(&fctx->fence_ref, nouveau_fence_context_put);
}

static int
nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx)
{
        struct nouveau_fence *fence;
        int drop = 0;
        u32 seq = fctx->read(chan);

        while (!list_empty(&fctx->pending)) {
                fence = list_entry(fctx->pending.next, typeof(*fence), head);

                if ((int)(seq - fence->base.seqno) < 0)
                        break;

                drop |= nouveau_fence_signal(fence);
        }

        return drop;
}

static int
nouveau_fence_wait_uevent_handler(struct nvif_notify *notify)
{
        struct nouveau_fence_chan *fctx =
                container_of(notify, typeof(*fctx), notify);
        unsigned long flags;
        int ret = NVIF_NOTIFY_KEEP;

        spin_lock_irqsave(&fctx->lock, flags);
        if (!list_empty(&fctx->pending)) {
                struct nouveau_fence *fence;
                struct nouveau_channel *chan;

                fence = list_entry(fctx->pending.next, typeof(*fence), head);
                chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock));
                if (nouveau_fence_update(fence->channel, fctx))
                        ret = NVIF_NOTIFY_DROP;
        }
        spin_unlock_irqrestore(&fctx->lock, flags);

        return ret;
}

void
nouveau_fence_context_new(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx)
{
        struct nouveau_fence_priv *priv = (void*)chan->drm->fence;
        struct nouveau_cli *cli = (void *)chan->user.client;
        int ret;

        INIT_LIST_HEAD(&fctx->flip);
        INIT_LIST_HEAD(&fctx->pending);
        spin_lock_init(&fctx->lock);
        fctx->context = priv->context_base + chan->chid;

        if (chan == chan->drm->cechan)
                strcpy(fctx->name, "copy engine channel");
        else if (chan == chan->drm->channel)
                strcpy(fctx->name, "generic kernel channel");
        else
                strcpy(fctx->name, nvxx_client(&cli->base)->name);

        kref_init(&fctx->fence_ref);
        if (!priv->uevent)
                return;

        ret = nvif_notify_init(&chan->user, nouveau_fence_wait_uevent_handler,
                               false, G82_CHANNEL_DMA_V0_NTFY_UEVENT,
                               &(struct nvif_notify_uevent_req) { },
                               sizeof(struct nvif_notify_uevent_req),
                               sizeof(struct nvif_notify_uevent_rep),
                               &fctx->notify);

        WARN_ON(ret);
}

struct nouveau_fence_work {
        struct work_struct work;
        struct fence_cb cb;
        void (*func)(void *);
        void *data;
};

static void
nouveau_fence_work_handler(struct work_struct *kwork)
{
        struct nouveau_fence_work *work = container_of(kwork, typeof(*work), work);
        work->func(work->data);
        kfree(work);
}

static void nouveau_fence_work_cb(struct fence *fence, struct fence_cb *cb)
{
        struct nouveau_fence_work *work = container_of(cb, typeof(*work), cb);

        schedule_work(&work->work);
}

void
nouveau_fence_work(struct fence *fence,
                   void (*func)(void *), void *data)
{
        struct nouveau_fence_work *work;

        if (fence_is_signaled(fence))
                goto err;

        work = kmalloc(sizeof(*work), GFP_KERNEL);
        if (!work) {
                /*
                 * this might not be a nouveau fence any more,
                 * so force a lazy wait here
                 */
                WARN_ON(nouveau_fence_wait((struct nouveau_fence *)fence,
                                           true, false));
                goto err;
        }

        INIT_WORK(&work->work, nouveau_fence_work_handler);
        work->func = func;
        work->data = data;

        if (fence_add_callback(fence, &work->cb, nouveau_fence_work_cb) < 0)
                goto err_free;
        return;

err_free:
        kfree(work);
err:
        func(data);
}

int
nouveau_fence_emit(struct nouveau_fence *fence, struct nouveau_channel *chan)
{
        struct nouveau_fence_chan *fctx = chan->fence;
        struct nouveau_fence_priv *priv = (void*)chan->drm->fence;
        int ret;

        fence->channel  = chan;
        fence->timeout  = jiffies + (15 * HZ);

        if (priv->uevent)
                fence_init(&fence->base, &nouveau_fence_ops_uevent,
                           &fctx->lock, fctx->context, ++fctx->sequence);
        else
                fence_init(&fence->base, &nouveau_fence_ops_legacy,
                           &fctx->lock, fctx->context, ++fctx->sequence);
        kref_get(&fctx->fence_ref);

        trace_fence_emit(&fence->base);
        ret = fctx->emit(fence);
        if (!ret) {
                fence_get(&fence->base);
                spin_lock_irq(&fctx->lock);

                if (nouveau_fence_update(chan, fctx))
                        nvif_notify_put(&fctx->notify);

                list_add_tail(&fence->head, &fctx->pending);
                spin_unlock_irq(&fctx->lock);
        }

        return ret;
}

bool
nouveau_fence_done(struct nouveau_fence *fence)
{
        if (fence->base.ops == &nouveau_fence_ops_legacy ||
            fence->base.ops == &nouveau_fence_ops_uevent) {
                struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
                struct nouveau_channel *chan;
                unsigned long flags;

                if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))
                        return true;

                spin_lock_irqsave(&fctx->lock, flags);
                chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock));
                if (chan && nouveau_fence_update(chan, fctx))
                        nvif_notify_put(&fctx->notify);
                spin_unlock_irqrestore(&fctx->lock, flags);
        }
        return fence_is_signaled(&fence->base);
}

static long
nouveau_fence_wait_legacy(struct fence *f, bool intr, long wait)
{
        struct nouveau_fence *fence = from_fence(f);
        unsigned long sleep_time = NSEC_PER_MSEC / 1000;
        unsigned long t = jiffies, timeout = t + wait;

        while (!nouveau_fence_done(fence)) {
                ktime_t kt;

                t = jiffies;

                if (wait != MAX_SCHEDULE_TIMEOUT && time_after_eq(t, timeout)) {
                        __set_current_state(TASK_RUNNING);
                        return 0;
                }

                __set_current_state(intr ? TASK_INTERRUPTIBLE :
                                           TASK_UNINTERRUPTIBLE);

                kt = ktime_set(0, sleep_time);
                schedule_hrtimeout(&kt, HRTIMER_MODE_REL);
                sleep_time *= 2;
                if (sleep_time > NSEC_PER_MSEC)
                        sleep_time = NSEC_PER_MSEC;

                if (intr && signal_pending(current))
                        return -ERESTARTSYS;
        }

        __set_current_state(TASK_RUNNING);

        return timeout - t;
}

static int
nouveau_fence_wait_busy(struct nouveau_fence *fence, bool intr)
{
        int ret = 0;

        while (!nouveau_fence_done(fence)) {
                if (time_after_eq(jiffies, fence->timeout)) {
                        ret = -EBUSY;
                        break;
                }

                __set_current_state(intr ?
                                    TASK_INTERRUPTIBLE :
                                    TASK_UNINTERRUPTIBLE);

                if (intr && signal_pending(current)) {
                        ret = -ERESTARTSYS;
                        break;
                }
        }

        __set_current_state(TASK_RUNNING);
        return ret;
}

int
nouveau_fence_wait(struct nouveau_fence *fence, bool lazy, bool intr)
{
        long ret;

        if (!lazy)
                return nouveau_fence_wait_busy(fence, intr);

        ret = fence_wait_timeout(&fence->base, intr, 15 * HZ);
        if (ret < 0)
                return ret;
        else if (!ret)
                return -EBUSY;
        else
                return 0;
}

int
nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool exclusive, bool intr)
{
        struct nouveau_fence_chan *fctx = chan->fence;
        struct fence *fence;
        struct reservation_object *resv = nvbo->bo.resv;
        struct reservation_object_list *fobj;
        struct nouveau_fence *f;
        int ret = 0, i;

        if (!exclusive) {
                ret = reservation_object_reserve_shared(resv);

                if (ret)
                        return ret;
        }

        fobj = reservation_object_get_list(resv);
        fence = reservation_object_get_excl(resv);

        if (fence && (!exclusive || !fobj || !fobj->shared_count)) {
                struct nouveau_channel *prev = NULL;
                bool must_wait = true;

                f = nouveau_local_fence(fence, chan->drm);
                if (f) {
                        rcu_read_lock();
                        prev = rcu_dereference(f->channel);
                        if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
                                must_wait = false;
                        rcu_read_unlock();
                }

                if (must_wait)
                        ret = fence_wait(fence, intr);

                return ret;
        }

        if (!exclusive || !fobj)
                return ret;

        for (i = 0; i < fobj->shared_count && !ret; ++i) {
                struct nouveau_channel *prev = NULL;
                bool must_wait = true;

                fence = rcu_dereference_protected(fobj->shared[i],
                                                reservation_object_held(resv));

                f = nouveau_local_fence(fence, chan->drm);
                if (f) {
                        rcu_read_lock();
                        prev = rcu_dereference(f->channel);
                        if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
                                must_wait = false;
                        rcu_read_unlock();
                }

                if (must_wait)
                        ret = fence_wait(fence, intr);
        }

        return ret;
}

void
nouveau_fence_unref(struct nouveau_fence **pfence)
{
        if (*pfence)
                fence_put(&(*pfence)->base);
        *pfence = NULL;
}

int
nouveau_fence_new(struct nouveau_channel *chan, bool sysmem,
                  struct nouveau_fence **pfence)
{
        struct nouveau_fence *fence;
        int ret = 0;

        if (unlikely(!chan->fence))
                return -ENODEV;

        fence = kzalloc(sizeof(*fence), GFP_KERNEL);
        if (!fence)
                return -ENOMEM;

        fence->sysmem = sysmem;

        ret = nouveau_fence_emit(fence, chan);
        if (ret)
                nouveau_fence_unref(&fence);

        *pfence = fence;
        return ret;
}

static const char *nouveau_fence_get_get_driver_name(struct fence *fence)
{
        return "nouveau";
}

static const char *nouveau_fence_get_timeline_name(struct fence *f)
{
        struct nouveau_fence *fence = from_fence(f);
        struct nouveau_fence_chan *fctx = nouveau_fctx(fence);

        return !fctx->dead ? fctx->name : "dead channel";
}

/*
 * In an ideal world, read would not assume the channel context is still alive.
 * This function may be called from another device, running into free memory as a
 * result. The drm node should still be there, so we can derive the index from
 * the fence context.
 */
static bool nouveau_fence_is_signaled(struct fence *f)
{
        struct nouveau_fence *fence = from_fence(f);
        struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
        struct nouveau_channel *chan;
        bool ret = false;

        rcu_read_lock();
        chan = rcu_dereference(fence->channel);
        if (chan)
                ret = (int)(fctx->read(chan) - fence->base.seqno) >= 0;
        rcu_read_unlock();

        return ret;
}

static bool nouveau_fence_no_signaling(struct fence *f)
{
        struct nouveau_fence *fence = from_fence(f);

        /*
         * caller should have a reference on the fence,
         * else fence could get freed here
         */
        WARN_ON(atomic_read(&fence->base.refcount.refcount) <= 1);

        /*
         * This needs uevents to work correctly, but fence_add_callback relies on
         * being able to enable signaling. It will still get signaled eventually,
         * just not right away.
         */
        if (nouveau_fence_is_signaled(f)) {
                list_del(&fence->head);

                fence_put(&fence->base);
                return false;
        }

        return true;
}

static void nouveau_fence_release(struct fence *f)
{
        struct nouveau_fence *fence = from_fence(f);
        struct nouveau_fence_chan *fctx = nouveau_fctx(fence);

        kref_put(&fctx->fence_ref, nouveau_fence_context_put);
        fence_free(&fence->base);
}

static const struct fence_ops nouveau_fence_ops_legacy = {
        .get_driver_name = nouveau_fence_get_get_driver_name,
        .get_timeline_name = nouveau_fence_get_timeline_name,
        .enable_signaling = nouveau_fence_no_signaling,
        .signaled = nouveau_fence_is_signaled,
        .wait = nouveau_fence_wait_legacy,
        .release = nouveau_fence_release
};

static bool nouveau_fence_enable_signaling(struct fence *f)
{
        struct nouveau_fence *fence = from_fence(f);
        struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
        bool ret;

        if (!fctx->notify_ref++)
                nvif_notify_get(&fctx->notify);

        ret = nouveau_fence_no_signaling(f);
        if (ret)
                set_bit(FENCE_FLAG_USER_BITS, &fence->base.flags);
        else if (!--fctx->notify_ref)
                nvif_notify_put(&fctx->notify);

        return ret;
}

static const struct fence_ops nouveau_fence_ops_uevent = {
        .get_driver_name = nouveau_fence_get_get_driver_name,
        .get_timeline_name = nouveau_fence_get_timeline_name,
        .enable_signaling = nouveau_fence_enable_signaling,
        .signaled = nouveau_fence_is_signaled,
        .wait = fence_default_wait,
        .release = NULL
};