/*
 * Copyright © 2008-2010 Intel Corporation
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS 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:
 *    Eric Anholt <eric@anholt.net>
 *    Chris Wilson <chris@chris-wilson.co.uuk>
 *
 */

#include <drm/drmP.h>
#include <drm/i915_drm.h>

#include "i915_drv.h"
#include "intel_drv.h"
#include "i915_trace.h"

static int switch_to_pinned_context(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;

        if (i915.enable_execlists)
                return 0;

        for_each_engine(engine, dev_priv) {
                struct drm_i915_gem_request *req;
                int ret;

                if (engine->last_context == NULL)
                        continue;

                if (engine->last_context == dev_priv->kernel_context)
                        continue;

                req = i915_gem_request_alloc(engine, dev_priv->kernel_context);
                if (IS_ERR(req))
                        return PTR_ERR(req);

                ret = i915_switch_context(req);
                i915_add_request_no_flush(req);
                if (ret)
                        return ret;
        }

        return 0;
}


static bool
mark_free(struct i915_vma *vma, struct list_head *unwind)
{
        if (vma->pin_count)
                return false;

        if (WARN_ON(!list_empty(&vma->exec_list)))
                return false;

        list_add(&vma->exec_list, unwind);
        return drm_mm_scan_add_block(&vma->node);
}

/**
 * i915_gem_evict_something - Evict vmas to make room for binding a new one
 * @dev: drm_device
 * @vm: address space to evict from
 * @min_size: size of the desired free space
 * @alignment: alignment constraint of the desired free space
 * @cache_level: cache_level for the desired space
 * @start: start (inclusive) of the range from which to evict objects
 * @end: end (exclusive) of the range from which to evict objects
 * @flags: additional flags to control the eviction algorithm
 *
 * This function will try to evict vmas until a free space satisfying the
 * requirements is found. Callers must check first whether any such hole exists
 * already before calling this function.
 *
 * This function is used by the object/vma binding code.
 *
 * Since this function is only used to free up virtual address space it only
 * ignores pinned vmas, and not object where the backing storage itself is
 * pinned. Hence obj->pages_pin_count does not protect against eviction.
 *
 * To clarify: This is for freeing up virtual address space, not for freeing
 * memory in e.g. the shrinker.
 */
int
i915_gem_evict_something(struct drm_device *dev, struct i915_address_space *vm,
                         int min_size, unsigned alignment, unsigned cache_level,
                         unsigned long start, unsigned long end,
                         unsigned flags)
{
        struct list_head eviction_list, unwind_list;
        struct i915_vma *vma;
        int ret = 0;
        int pass = 0;

        trace_i915_gem_evict(dev, min_size, alignment, flags);

        /*
         * The goal is to evict objects and amalgamate space in LRU order.
         * The oldest idle objects reside on the inactive list, which is in
         * retirement order. The next objects to retire are those on the (per
         * ring) active list that do not have an outstanding flush. Once the
         * hardware reports completion (the seqno is updated after the
         * batchbuffer has been finished) the clean buffer objects would
         * be retired to the inactive list. Any dirty objects would be added
         * to the tail of the flushing list. So after processing the clean
         * active objects we need to emit a MI_FLUSH to retire the flushing
         * list, hence the retirement order of the flushing list is in
         * advance of the dirty objects on the active lists.
         *
         * The retirement sequence is thus:
         *   1. Inactive objects (already retired)
         *   2. Clean active objects
         *   3. Flushing list
         *   4. Dirty active objects.
         *
         * On each list, the oldest objects lie at the HEAD with the freshest
         * object on the TAIL.
         */

        INIT_LIST_HEAD(&unwind_list);
        if (start != 0 || end != vm->total) {
                drm_mm_init_scan_with_range(&vm->mm, min_size,
                                            alignment, cache_level,
                                            start, end);
        } else
                drm_mm_init_scan(&vm->mm, min_size, alignment, cache_level);

search_again:
        /* First see if there is a large enough contiguous idle region... */
        list_for_each_entry(vma, &vm->inactive_list, vm_link) {
                if (mark_free(vma, &unwind_list))
                        goto found;
        }

        if (flags & PIN_NONBLOCK)
                goto none;

        /* Now merge in the soon-to-be-expired objects... */
        list_for_each_entry(vma, &vm->active_list, vm_link) {
                if (mark_free(vma, &unwind_list))
                        goto found;
        }

none:
        /* Nothing found, clean up and bail out! */
        while (!list_empty(&unwind_list)) {
                vma = list_first_entry(&unwind_list,
                                       struct i915_vma,
                                       exec_list);
                ret = drm_mm_scan_remove_block(&vma->node);
                BUG_ON(ret);

                list_del_init(&vma->exec_list);
        }

        /* Can we unpin some objects such as idle hw contents,
         * or pending flips?
         */
        if (flags & PIN_NONBLOCK)
                return -ENOSPC;

        /* Only idle the GPU and repeat the search once */
        if (pass++ == 0) {
                struct drm_i915_private *dev_priv = to_i915(dev);

                if (i915_is_ggtt(vm)) {
                        ret = switch_to_pinned_context(dev_priv);
                        if (ret)
                                return ret;
                }

                ret = i915_gem_wait_for_idle(dev_priv);
                if (ret)
                        return ret;

                i915_gem_retire_requests(dev_priv);
                goto search_again;
        }

        /* If we still have pending pageflip completions, drop
         * back to userspace to give our workqueues time to
         * acquire our locks and unpin the old scanouts.
         */
        return intel_has_pending_fb_unpin(dev) ? -EAGAIN : -ENOSPC;

found:
        /* drm_mm doesn't allow any other other operations while
         * scanning, therefore store to be evicted objects on a
         * temporary list. */
        INIT_LIST_HEAD(&eviction_list);
        while (!list_empty(&unwind_list)) {
                vma = list_first_entry(&unwind_list,
                                       struct i915_vma,
                                       exec_list);
                if (drm_mm_scan_remove_block(&vma->node)) {
                        list_move(&vma->exec_list, &eviction_list);
                        drm_gem_object_reference(&vma->obj->base);
                        continue;
                }
                list_del_init(&vma->exec_list);
        }

        /* Unbinding will emit any required flushes */
        while (!list_empty(&eviction_list)) {
                struct drm_gem_object *obj;
                vma = list_first_entry(&eviction_list,
                                       struct i915_vma,
                                       exec_list);

                obj =  &vma->obj->base;
                list_del_init(&vma->exec_list);
                if (ret == 0)
                        ret = i915_vma_unbind(vma);

                drm_gem_object_unreference(obj);
        }

        return ret;
}

int
i915_gem_evict_for_vma(struct i915_vma *target)
{
        struct drm_mm_node *node, *next;

        list_for_each_entry_safe(node, next,
                        &target->vm->mm.head_node.node_list,
                        node_list) {
                struct i915_vma *vma;
                int ret;

                if (node->start + node->size <= target->node.start)
                        continue;
                if (node->start >= target->node.start + target->node.size)
                        break;

                vma = container_of(node, typeof(*vma), node);

                if (vma->pin_count) {
                        if (!vma->exec_entry || (vma->pin_count > 1))
                                /* Object is pinned for some other use */
                                return -EBUSY;

                        /* We need to evict a buffer in the same batch */
                        if (vma->exec_entry->flags & EXEC_OBJECT_PINNED)
                                /* Overlapping fixed objects in the same batch */
                                return -EINVAL;

                        return -ENOSPC;
                }

                ret = i915_vma_unbind(vma);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * i915_gem_evict_vm - Evict all idle vmas from a vm
 * @vm: Address space to cleanse
 * @do_idle: Boolean directing whether to idle first.
 *
 * This function evicts all idles vmas from a vm. If all unpinned vmas should be
 * evicted the @do_idle needs to be set to true.
 *
 * This is used by the execbuf code as a last-ditch effort to defragment the
 * address space.
 *
 * To clarify: This is for freeing up virtual address space, not for freeing
 * memory in e.g. the shrinker.
 */
int i915_gem_evict_vm(struct i915_address_space *vm, bool do_idle)
{
        struct i915_vma *vma, *next;
        int ret;

        WARN_ON(!mutex_is_locked(&vm->dev->struct_mutex));
        trace_i915_gem_evict_vm(vm);

        if (do_idle) {
                struct drm_i915_private *dev_priv = to_i915(vm->dev);

                if (i915_is_ggtt(vm)) {
                        ret = switch_to_pinned_context(dev_priv);
                        if (ret)
                                return ret;
                }

                ret = i915_gem_wait_for_idle(dev_priv);
                if (ret)
                        return ret;

                i915_gem_retire_requests(dev_priv);

                WARN_ON(!list_empty(&vm->active_list));
        }

        list_for_each_entry_safe(vma, next, &vm->inactive_list, vm_link)
                if (vma->pin_count == 0)
                        WARN_ON(i915_vma_unbind(vma));

        return 0;
}