/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2019 Intel Corporation
 */

#include "gem/i915_gem_context.h"
#include "gem/i915_gem_pm.h"

#include "i915_drv.h"
#include "i915_globals.h"

#include "intel_context.h"
#include "intel_engine.h"
#include "intel_engine_pm.h"
#include "intel_ring.h"

static struct i915_global_context {
        struct i915_global base;
        struct kmem_cache *slab_ce;
} global;

static struct intel_context *intel_context_alloc(void)
{
        return kmem_cache_zalloc(global.slab_ce, GFP_KERNEL);
}

void intel_context_free(struct intel_context *ce)
{
        kmem_cache_free(global.slab_ce, ce);
}

struct intel_context *
intel_context_create(struct intel_engine_cs *engine)
{
        struct intel_context *ce;

        ce = intel_context_alloc();
        if (!ce)
                return ERR_PTR(-ENOMEM);

        intel_context_init(ce, engine);
        return ce;
}

int intel_context_alloc_state(struct intel_context *ce)
{
        int err = 0;

        if (mutex_lock_interruptible(&ce->pin_mutex))
                return -EINTR;

        if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
                err = ce->ops->alloc(ce);
                if (unlikely(err))
                        goto unlock;

                set_bit(CONTEXT_ALLOC_BIT, &ce->flags);
        }

unlock:
        mutex_unlock(&ce->pin_mutex);
        return err;
}

static int intel_context_active_acquire(struct intel_context *ce)
{
        int err;

        __i915_active_acquire(&ce->active);

        if (intel_context_is_barrier(ce))
                return 0;

        /* Preallocate tracking nodes */
        err = i915_active_acquire_preallocate_barrier(&ce->active,
                                                      ce->engine);
        if (err)
                i915_active_release(&ce->active);

        return err;
}

static void intel_context_active_release(struct intel_context *ce)
{
        /* Nodes preallocated in intel_context_active() */
        i915_active_acquire_barrier(&ce->active);
        i915_active_release(&ce->active);
}

int __intel_context_do_pin(struct intel_context *ce)
{
        int err;

        if (unlikely(!test_bit(CONTEXT_ALLOC_BIT, &ce->flags))) {
                err = intel_context_alloc_state(ce);
                if (err)
                        return err;
        }

        err = i915_active_acquire(&ce->active);
        if (err)
                return err;

        if (mutex_lock_interruptible(&ce->pin_mutex)) {
                err = -EINTR;
                goto out_release;
        }

        if (likely(!atomic_add_unless(&ce->pin_count, 1, 0))) {
                err = intel_context_active_acquire(ce);
                if (unlikely(err))
                        goto out_unlock;

                err = ce->ops->pin(ce);
                if (unlikely(err))
                        goto err_active;

                CE_TRACE(ce, "pin ring:{head:%04x, tail:%04x}\n",
                         ce->ring->head, ce->ring->tail);

                smp_mb__before_atomic(); /* flush pin before it is visible */
                atomic_inc(&ce->pin_count);
        }

        GEM_BUG_ON(!intel_context_is_pinned(ce)); /* no overflow! */
        GEM_BUG_ON(i915_active_is_idle(&ce->active));
        goto out_unlock;

err_active:
        intel_context_active_release(ce);
out_unlock:
        mutex_unlock(&ce->pin_mutex);
out_release:
        i915_active_release(&ce->active);
        return err;
}

void intel_context_unpin(struct intel_context *ce)
{
        if (!atomic_dec_and_test(&ce->pin_count))
                return;

        CE_TRACE(ce, "unpin\n");
        ce->ops->unpin(ce);

        /*
         * Once released, we may asynchronously drop the active reference.
         * As that may be the only reference keeping the context alive,
         * take an extra now so that it is not freed before we finish
         * dereferencing it.
         */
        intel_context_get(ce);
        intel_context_active_release(ce);
        intel_context_put(ce);
}

static int __context_pin_state(struct i915_vma *vma)
{
        unsigned int bias = i915_ggtt_pin_bias(vma) | PIN_OFFSET_BIAS;
        int err;

        err = i915_ggtt_pin(vma, 0, bias | PIN_HIGH);
        if (err)
                return err;

        err = i915_active_acquire(&vma->active);
        if (err)
                goto err_unpin;

        /*
         * And mark it as a globally pinned object to let the shrinker know
         * it cannot reclaim the object until we release it.
         */
        i915_vma_make_unshrinkable(vma);
        vma->obj->mm.dirty = true;

        return 0;

err_unpin:
        i915_vma_unpin(vma);
        return err;
}

static void __context_unpin_state(struct i915_vma *vma)
{
        i915_vma_make_shrinkable(vma);
        i915_active_release(&vma->active);
        __i915_vma_unpin(vma);
}

static int __ring_active(struct intel_ring *ring)
{
        int err;

        err = i915_active_acquire(&ring->vma->active);
        if (err)
                return err;

        err = intel_ring_pin(ring);
        if (err)
                goto err_active;

        return 0;

err_active:
        i915_active_release(&ring->vma->active);
        return err;
}

static void __ring_retire(struct intel_ring *ring)
{
        intel_ring_unpin(ring);
        i915_active_release(&ring->vma->active);
}

__i915_active_call
static void __intel_context_retire(struct i915_active *active)
{
        struct intel_context *ce = container_of(active, typeof(*ce), active);

        CE_TRACE(ce, "retire\n");

        set_bit(CONTEXT_VALID_BIT, &ce->flags);
        if (ce->state)
                __context_unpin_state(ce->state);

        intel_timeline_unpin(ce->timeline);
        __ring_retire(ce->ring);

        intel_context_put(ce);
}

static int __intel_context_active(struct i915_active *active)
{
        struct intel_context *ce = container_of(active, typeof(*ce), active);
        int err;

        CE_TRACE(ce, "active\n");

        intel_context_get(ce);

        err = __ring_active(ce->ring);
        if (err)
                goto err_put;

        err = intel_timeline_pin(ce->timeline);
        if (err)
                goto err_ring;

        if (!ce->state)
                return 0;

        err = __context_pin_state(ce->state);
        if (err)
                goto err_timeline;

        return 0;

err_timeline:
        intel_timeline_unpin(ce->timeline);
err_ring:
        __ring_retire(ce->ring);
err_put:
        intel_context_put(ce);
        return err;
}

void
intel_context_init(struct intel_context *ce,
                   struct intel_engine_cs *engine)
{
        GEM_BUG_ON(!engine->cops);
        GEM_BUG_ON(!engine->gt->vm);

        kref_init(&ce->ref);

        ce->engine = engine;
        ce->ops = engine->cops;
        ce->sseu = engine->sseu;
        ce->ring = __intel_context_ring_size(SZ_4K);

        ce->vm = i915_vm_get(engine->gt->vm);

        INIT_LIST_HEAD(&ce->signal_link);
        INIT_LIST_HEAD(&ce->signals);

        mutex_init(&ce->pin_mutex);

        i915_active_init(&ce->active,
                         __intel_context_active, __intel_context_retire);
}

void intel_context_fini(struct intel_context *ce)
{
        if (ce->timeline)
                intel_timeline_put(ce->timeline);
        i915_vm_put(ce->vm);

        mutex_destroy(&ce->pin_mutex);
        i915_active_fini(&ce->active);
}

static void i915_global_context_shrink(void)
{
        kmem_cache_shrink(global.slab_ce);
}

static void i915_global_context_exit(void)
{
        kmem_cache_destroy(global.slab_ce);
}

static struct i915_global_context global = { {
        .shrink = i915_global_context_shrink,
        .exit = i915_global_context_exit,
} };

int __init i915_global_context_init(void)
{
        global.slab_ce = KMEM_CACHE(intel_context, SLAB_HWCACHE_ALIGN);
        if (!global.slab_ce)
                return -ENOMEM;

        i915_global_register(&global.base);
        return 0;
}

void intel_context_enter_engine(struct intel_context *ce)
{
        intel_engine_pm_get(ce->engine);
        intel_timeline_enter(ce->timeline);
}

void intel_context_exit_engine(struct intel_context *ce)
{
        intel_timeline_exit(ce->timeline);
        intel_engine_pm_put(ce->engine);
}

int intel_context_prepare_remote_request(struct intel_context *ce,
                                         struct i915_request *rq)
{
        struct intel_timeline *tl = ce->timeline;
        int err;

        /* Only suitable for use in remotely modifying this context */
        GEM_BUG_ON(rq->context == ce);

        if (rcu_access_pointer(rq->timeline) != tl) { /* timeline sharing! */
                /* Queue this switch after current activity by this context. */
                err = i915_active_fence_set(&tl->last_request, rq);
                if (err)
                        return err;
        }

        /*
         * Guarantee context image and the timeline remains pinned until the
         * modifying request is retired by setting the ce activity tracker.
         *
         * But we only need to take one pin on the account of it. Or in other
         * words transfer the pinned ce object to tracked active request.
         */
        GEM_BUG_ON(i915_active_is_idle(&ce->active));
        return i915_active_add_request(&ce->active, rq);
}

struct i915_request *intel_context_create_request(struct intel_context *ce)
{
        struct i915_request *rq;
        int err;

        err = intel_context_pin(ce);
        if (unlikely(err))
                return ERR_PTR(err);

        rq = i915_request_create(ce);
        intel_context_unpin(ce);

        return rq;
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_context.c"
#endif