/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/**************************************************************************
 *
 * 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 <linux/export.h>

#include <drm/ttm/ttm_execbuf_util.h>
#include <drm/ttm/ttm_bo.h>

static void ttm_eu_backoff_reservation_reverse(struct list_head *list,
                                              struct ttm_validate_buffer *entry)
{
        list_for_each_entry_continue_reverse(entry, list, head) {
                struct ttm_buffer_object *bo = entry->bo;

                dma_resv_unlock(bo->base.resv);
        }
}

void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
                                struct list_head *list)
{
        struct ttm_validate_buffer *entry;

        if (list_empty(list))
                return;

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

                ttm_bo_move_to_lru_tail_unlocked(bo);
                dma_resv_unlock(bo->base.resv);
        }

        if (ticket)
                ww_acquire_fini(ticket);
}
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 ww_acquire_ctx *ticket,
                           struct list_head *list, bool intr,
                           struct list_head *dups)
{
        struct ttm_validate_buffer *entry;
        int ret;

        if (list_empty(list))
                return 0;

        if (ticket)
                ww_acquire_init(ticket, &reservation_ww_class);

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

                ret = ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
                if (ret == -EALREADY && dups) {
                        struct ttm_validate_buffer *safe = entry;
                        entry = list_prev_entry(entry, head);
                        list_del(&safe->head);
                        list_add(&safe->head, dups);
                        continue;
                }

                num_fences = max(entry->num_shared, 1u);
                if (!ret) {
                        ret = dma_resv_reserve_fences(bo->base.resv,
                                                      num_fences);
                        if (!ret)
                                continue;
                }

                /* uh oh, we lost out, drop every reservation and try
                 * to only reserve this buffer, then start over if
                 * this succeeds.
                 */
                ttm_eu_backoff_reservation_reverse(list, entry);

                if (ret == -EDEADLK) {
                        ret = ttm_bo_reserve_slowpath(bo, intr, ticket);
                }

                if (!ret)
                        ret = dma_resv_reserve_fences(bo->base.resv,
                                                      num_fences);

                if (unlikely(ret != 0)) {
                        if (ticket) {
                                ww_acquire_done(ticket);
                                ww_acquire_fini(ticket);
                        }
                        return ret;
                }

                /* move this item to the front of the list,
                 * forces correct iteration of the loop without keeping track
                 */
                list_del(&entry->head);
                list_add(&entry->head, list);
        }

        return 0;
}
EXPORT_SYMBOL(ttm_eu_reserve_buffers);

void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
                                 struct list_head *list,
                                 struct dma_fence *fence)
{
        struct ttm_validate_buffer *entry;

        if (list_empty(list))
                return;

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

                dma_resv_add_fence(bo->base.resv, fence, entry->num_shared ?
                                   DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
                ttm_bo_move_to_lru_tail_unlocked(bo);
                dma_resv_unlock(bo->base.resv);
        }
        if (ticket)
                ww_acquire_fini(ticket);
}
EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);