/**************************************************************************
 *
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS 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/ttm/ttm_execbuf_util.h>
#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_placement.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/module.h>

static void ttm_eu_backoff_reservation_locked(struct list_head *list)
{
        struct ttm_validate_buffer *entry;

        list_for_each_entry(entry, list, head) {
                struct ttm_buffer_object *bo = entry->bo;
                if (!entry->reserved)
                        continue;

                if (entry->removed) {
                        ttm_bo_add_to_lru(bo);
                        entry->removed = false;

                }
                entry->reserved = false;
                atomic_set(&bo->reserved, 0);
                wake_up_all(&bo->event_queue);
        }
}

static void ttm_eu_del_from_lru_locked(struct list_head *list)
{
        struct ttm_validate_buffer *entry;

        list_for_each_entry(entry, list, head) {
                struct ttm_buffer_object *bo = entry->bo;
                if (!entry->reserved)
                        continue;

                if (!entry->removed) {
                        entry->put_count = ttm_bo_del_from_lru(bo);
                        entry->removed = true;
                }
        }
}

static void ttm_eu_list_ref_sub(struct list_head *list)
{
        struct ttm_validate_buffer *entry;

        list_for_each_entry(entry, list, head) {
                struct ttm_buffer_object *bo = entry->bo;

                if (entry->put_count) {
                        ttm_bo_list_ref_sub(bo, entry->put_count, true);
                        entry->put_count = 0;
                }
        }
}

void ttm_eu_backoff_reservation(struct list_head *list)
{
        struct ttm_validate_buffer *entry;
        struct ttm_bo_global *glob;

        if (list_empty(list))
                return;

        entry = list_first_entry(list, struct ttm_validate_buffer, head);
        glob = entry->bo->glob;
        spin_lock(&glob->lru_lock);
        ttm_eu_backoff_reservation_locked(list);
        spin_unlock(&glob->lru_lock);
}
EXPORT_SYMBOL(ttm_eu_backoff_reservation);

/*
 * Reserve buffers for validation.
 *
 * If a buffer in the list is marked for CPU access, we back off and
 * wait for that buffer to become free for GPU access.
 *
 * If a buffer is reserved for another validation, the validator with
 * the highest validation sequence backs off and waits for that buffer
 * to become unreserved. This prevents deadlocks when validating multiple
 * buffers in different orders.
 */

int ttm_eu_reserve_buffers(struct list_head *list)
{
        struct ttm_bo_global *glob;
        struct ttm_validate_buffer *entry;
        int ret;
        uint32_t val_seq;

        if (list_empty(list))
                return 0;

        list_for_each_entry(entry, list, head) {
                entry->reserved = false;
                entry->put_count = 0;
                entry->removed = false;
        }

        entry = list_first_entry(list, struct ttm_validate_buffer, head);
        glob = entry->bo->glob;

        spin_lock(&glob->lru_lock);
        val_seq = entry->bo->bdev->val_seq++;

retry:
        list_for_each_entry(entry, list, head) {
                struct ttm_buffer_object *bo = entry->bo;

                /* already slowpath reserved? */
                if (entry->reserved)
                        continue;

                ret = ttm_bo_reserve_nolru(bo, true, true, true, val_seq);
                switch (ret) {
                case 0:
                        break;
                case -EBUSY:
                        ttm_eu_del_from_lru_locked(list);
                        spin_unlock(&glob->lru_lock);
                        ret = ttm_bo_reserve_nolru(bo, true, false,
                                                   true, val_seq);
                        spin_lock(&glob->lru_lock);
                        if (!ret)
                                break;

                        if (unlikely(ret != -EAGAIN))
                                goto err;

                        /* fallthrough */
                case -EAGAIN:
                        ttm_eu_backoff_reservation_locked(list);

                        /*
                         * temporarily increase sequence number every retry,
                         * to prevent us from seeing our old reservation
                         * sequence when someone else reserved the buffer,
                         * but hasn't updated the seq_valid/seqno members yet.
                         */
                        val_seq = entry->bo->bdev->val_seq++;

                        spin_unlock(&glob->lru_lock);
                        ttm_eu_list_ref_sub(list);
                        ret = ttm_bo_reserve_slowpath_nolru(bo, true, val_seq);
                        if (unlikely(ret != 0))
                                return ret;
                        spin_lock(&glob->lru_lock);
                        entry->reserved = true;
                        if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
                                ret = -EBUSY;
                                goto err;
                        }
                        goto retry;
                default:
                        goto err;
                }

                entry->reserved = true;
                if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
                        ret = -EBUSY;
                        goto err;
                }
        }

        ttm_eu_del_from_lru_locked(list);
        spin_unlock(&glob->lru_lock);
        ttm_eu_list_ref_sub(list);

        return 0;

err:
        ttm_eu_backoff_reservation_locked(list);
        spin_unlock(&glob->lru_lock);
        ttm_eu_list_ref_sub(list);
        return ret;
}
EXPORT_SYMBOL(ttm_eu_reserve_buffers);

void ttm_eu_fence_buffer_objects(struct list_head *list, void *sync_obj)
{
        struct ttm_validate_buffer *entry;
        struct ttm_buffer_object *bo;
        struct ttm_bo_global *glob;
        struct ttm_bo_device *bdev;
        struct ttm_bo_driver *driver;

        if (list_empty(list))
                return;

        bo = list_first_entry(list, struct ttm_validate_buffer, head)->bo;
        bdev = bo->bdev;
        driver = bdev->driver;
        glob = bo->glob;

        spin_lock(&glob->lru_lock);
        spin_lock(&bdev->fence_lock);

        list_for_each_entry(entry, list, head) {
                bo = entry->bo;
                entry->old_sync_obj = bo->sync_obj;
                bo->sync_obj = driver->sync_obj_ref(sync_obj);
                ttm_bo_unreserve_locked(bo);
                entry->reserved = false;
        }
        spin_unlock(&bdev->fence_lock);
        spin_unlock(&glob->lru_lock);

        list_for_each_entry(entry, list, head) {
                if (entry->old_sync_obj)
                        driver->sync_obj_unref(&entry->old_sync_obj);
        }
}
EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);