// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
 * Copyright 2011 Red Hat Inc.
 * Copyright 2023 Intel Corporation.
 * 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 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.
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 */
/* Algorithm:
 *
 * We store the last allocated bo in "hole", we always try to allocate
 * after the last allocated bo. Principle is that in a linear GPU ring
 * progression was is after last is the oldest bo we allocated and thus
 * the first one that should no longer be in use by the GPU.
 *
 * If it's not the case we skip over the bo after last to the closest
 * done bo if such one exist. If none exist and we are not asked to
 * block we report failure to allocate.
 *
 * If we are asked to block we wait on all the oldest fence of all
 * rings. We just wait for any of those fence to complete.
 */

#include <drm/drm_suballoc.h>
#include <drm/drm_print.h>

#include <linux/export.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/dma-fence.h>

static void drm_suballoc_remove_locked(struct drm_suballoc *sa);
static void drm_suballoc_try_free(struct drm_suballoc_manager *sa_manager);

/**
 * drm_suballoc_manager_init() - Initialise the drm_suballoc_manager
 * @sa_manager: pointer to the sa_manager
 * @size: number of bytes we want to suballocate
 * @align: alignment for each suballocated chunk
 *
 * Prepares the suballocation manager for suballocations.
 */
void drm_suballoc_manager_init(struct drm_suballoc_manager *sa_manager,
                               size_t size, size_t align)
{
        unsigned int i;

        BUILD_BUG_ON(!is_power_of_2(DRM_SUBALLOC_MAX_QUEUES));

        if (!align)
                align = 1;

        /* alignment must be a power of 2 */
        if (WARN_ON_ONCE(align & (align - 1)))
                align = roundup_pow_of_two(align);

        init_waitqueue_head(&sa_manager->wq);
        sa_manager->size = size;
        sa_manager->align = align;
        sa_manager->hole = &sa_manager->olist;
        INIT_LIST_HEAD(&sa_manager->olist);
        for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
                INIT_LIST_HEAD(&sa_manager->flist[i]);
}
EXPORT_SYMBOL(drm_suballoc_manager_init);

/**
 * drm_suballoc_manager_fini() - Destroy the drm_suballoc_manager
 * @sa_manager: pointer to the sa_manager
 *
 * Cleans up the suballocation manager after use. All fences added
 * with drm_suballoc_free() must be signaled, or we cannot clean up
 * the entire manager.
 */
void drm_suballoc_manager_fini(struct drm_suballoc_manager *sa_manager)
{
        struct drm_suballoc *sa, *tmp;

        if (!sa_manager->size)
                return;

        if (!list_empty(&sa_manager->olist)) {
                sa_manager->hole = &sa_manager->olist;
                drm_suballoc_try_free(sa_manager);
                if (!list_empty(&sa_manager->olist))
                        DRM_ERROR("sa_manager is not empty, clearing anyway\n");
        }
        list_for_each_entry_safe(sa, tmp, &sa_manager->olist, olist) {
                drm_suballoc_remove_locked(sa);
        }

        sa_manager->size = 0;
}
EXPORT_SYMBOL(drm_suballoc_manager_fini);

static void drm_suballoc_remove_locked(struct drm_suballoc *sa)
{
        struct drm_suballoc_manager *sa_manager = sa->manager;

        if (sa_manager->hole == &sa->olist)
                sa_manager->hole = sa->olist.prev;

        list_del_init(&sa->olist);
        list_del_init(&sa->flist);
        dma_fence_put(sa->fence);
        kfree(sa);
}

static void drm_suballoc_try_free(struct drm_suballoc_manager *sa_manager)
{
        struct drm_suballoc *sa, *tmp;

        if (sa_manager->hole->next == &sa_manager->olist)
                return;

        sa = list_entry(sa_manager->hole->next, struct drm_suballoc, olist);
        list_for_each_entry_safe_from(sa, tmp, &sa_manager->olist, olist) {
                if (!sa->fence || !dma_fence_is_signaled(sa->fence))
                        return;

                drm_suballoc_remove_locked(sa);
        }
}

static size_t drm_suballoc_hole_soffset(struct drm_suballoc_manager *sa_manager)
{
        struct list_head *hole = sa_manager->hole;

        if (hole != &sa_manager->olist)
                return list_entry(hole, struct drm_suballoc, olist)->eoffset;

        return 0;
}

static size_t drm_suballoc_hole_eoffset(struct drm_suballoc_manager *sa_manager)
{
        struct list_head *hole = sa_manager->hole;

        if (hole->next != &sa_manager->olist)
                return list_entry(hole->next, struct drm_suballoc, olist)->soffset;
        return sa_manager->size;
}

static bool drm_suballoc_try_alloc(struct drm_suballoc_manager *sa_manager,
                                   struct drm_suballoc *sa,
                                   size_t size, size_t align)
{
        size_t soffset, eoffset, wasted;

        soffset = drm_suballoc_hole_soffset(sa_manager);
        eoffset = drm_suballoc_hole_eoffset(sa_manager);
        wasted = round_up(soffset, align) - soffset;

        if ((eoffset - soffset) >= (size + wasted)) {
                soffset += wasted;

                sa->manager = sa_manager;
                sa->soffset = soffset;
                sa->eoffset = soffset + size;
                list_add(&sa->olist, sa_manager->hole);
                INIT_LIST_HEAD(&sa->flist);
                sa_manager->hole = &sa->olist;
                return true;
        }
        return false;
}

static bool __drm_suballoc_event(struct drm_suballoc_manager *sa_manager,
                                 size_t size, size_t align)
{
        size_t soffset, eoffset, wasted;
        unsigned int i;

        for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
                if (!list_empty(&sa_manager->flist[i]))
                        return true;

        soffset = drm_suballoc_hole_soffset(sa_manager);
        eoffset = drm_suballoc_hole_eoffset(sa_manager);
        wasted = round_up(soffset, align) - soffset;

        return ((eoffset - soffset) >= (size + wasted));
}

/**
 * drm_suballoc_event() - Check if we can stop waiting
 * @sa_manager: pointer to the sa_manager
 * @size: number of bytes we want to allocate
 * @align: alignment we need to match
 *
 * Return: true if either there is a fence we can wait for or
 * enough free memory to satisfy the allocation directly.
 * false otherwise.
 */
static bool drm_suballoc_event(struct drm_suballoc_manager *sa_manager,
                               size_t size, size_t align)
{
        bool ret;

        spin_lock(&sa_manager->wq.lock);
        ret = __drm_suballoc_event(sa_manager, size, align);
        spin_unlock(&sa_manager->wq.lock);
        return ret;
}

static bool drm_suballoc_next_hole(struct drm_suballoc_manager *sa_manager,
                                   struct dma_fence **fences,
                                   unsigned int *tries)
{
        struct drm_suballoc *best_bo = NULL;
        unsigned int i, best_idx;
        size_t soffset, best, tmp;

        /* if hole points to the end of the buffer */
        if (sa_manager->hole->next == &sa_manager->olist) {
                /* try again with its beginning */
                sa_manager->hole = &sa_manager->olist;
                return true;
        }

        soffset = drm_suballoc_hole_soffset(sa_manager);
        /* to handle wrap around we add sa_manager->size */
        best = sa_manager->size * 2;
        /* go over all fence list and try to find the closest sa
         * of the current last
         */
        for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i) {
                struct drm_suballoc *sa;

                fences[i] = NULL;

                if (list_empty(&sa_manager->flist[i]))
                        continue;

                sa = list_first_entry(&sa_manager->flist[i],
                                      struct drm_suballoc, flist);

                if (!dma_fence_is_signaled(sa->fence)) {
                        fences[i] = sa->fence;
                        continue;
                }

                /* limit the number of tries each freelist gets */
                if (tries[i] > 2)
                        continue;

                tmp = sa->soffset;
                if (tmp < soffset) {
                        /* wrap around, pretend it's after */
                        tmp += sa_manager->size;
                }
                tmp -= soffset;
                if (tmp < best) {
                        /* this sa bo is the closest one */
                        best = tmp;
                        best_idx = i;
                        best_bo = sa;
                }
        }

        if (best_bo) {
                ++tries[best_idx];
                sa_manager->hole = best_bo->olist.prev;

                /*
                 * We know that this one is signaled,
                 * so it's safe to remove it.
                 */
                drm_suballoc_remove_locked(best_bo);
                return true;
        }
        return false;
}

/**
 * drm_suballoc_new() - Make a suballocation.
 * @sa_manager: pointer to the sa_manager
 * @size: number of bytes we want to suballocate.
 * @gfp: gfp flags used for memory allocation. Typically GFP_KERNEL but
 *       the argument is provided for suballocations from reclaim context or
 *       where the caller wants to avoid pipelining rather than wait for
 *       reclaim.
 * @intr: Whether to perform waits interruptible. This should typically
 *        always be true, unless the caller needs to propagate a
 *        non-interruptible context from above layers.
 * @align: Alignment. Must not exceed the default manager alignment.
 *         If @align is zero, then the manager alignment is used.
 *
 * Try to make a suballocation of size @size, which will be rounded
 * up to the alignment specified in specified in drm_suballoc_manager_init().
 *
 * Return: a new suballocated bo, or an ERR_PTR.
 */
struct drm_suballoc *
drm_suballoc_new(struct drm_suballoc_manager *sa_manager, size_t size,
                 gfp_t gfp, bool intr, size_t align)
{
        struct dma_fence *fences[DRM_SUBALLOC_MAX_QUEUES];
        unsigned int tries[DRM_SUBALLOC_MAX_QUEUES];
        unsigned int count;
        int i, r;
        struct drm_suballoc *sa;

        if (WARN_ON_ONCE(align > sa_manager->align))
                return ERR_PTR(-EINVAL);
        if (WARN_ON_ONCE(size > sa_manager->size || !size))
                return ERR_PTR(-EINVAL);

        if (!align)
                align = sa_manager->align;

        sa = kmalloc_obj(*sa, gfp);
        if (!sa)
                return ERR_PTR(-ENOMEM);
        sa->manager = sa_manager;
        sa->fence = NULL;
        INIT_LIST_HEAD(&sa->olist);
        INIT_LIST_HEAD(&sa->flist);

        spin_lock(&sa_manager->wq.lock);
        do {
                for (i = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
                        tries[i] = 0;

                do {
                        drm_suballoc_try_free(sa_manager);

                        if (drm_suballoc_try_alloc(sa_manager, sa,
                                                   size, align)) {
                                spin_unlock(&sa_manager->wq.lock);
                                return sa;
                        }

                        /* see if we can skip over some allocations */
                } while (drm_suballoc_next_hole(sa_manager, fences, tries));

                for (i = 0, count = 0; i < DRM_SUBALLOC_MAX_QUEUES; ++i)
                        if (fences[i])
                                fences[count++] = dma_fence_get(fences[i]);

                if (count) {
                        long t;

                        spin_unlock(&sa_manager->wq.lock);
                        t = dma_fence_wait_any_timeout(fences, count, intr,
                                                       MAX_SCHEDULE_TIMEOUT,
                                                       NULL);
                        for (i = 0; i < count; ++i)
                                dma_fence_put(fences[i]);

                        r = (t > 0) ? 0 : t;
                        spin_lock(&sa_manager->wq.lock);
                } else if (intr) {
                        /* if we have nothing to wait for block */
                        r = wait_event_interruptible_locked
                                (sa_manager->wq,
                                 __drm_suballoc_event(sa_manager, size, align));
                } else {
                        spin_unlock(&sa_manager->wq.lock);
                        wait_event(sa_manager->wq,
                                   drm_suballoc_event(sa_manager, size, align));
                        r = 0;
                        spin_lock(&sa_manager->wq.lock);
                }
        } while (!r);

        spin_unlock(&sa_manager->wq.lock);
        kfree(sa);
        return ERR_PTR(r);
}
EXPORT_SYMBOL(drm_suballoc_new);

/**
 * drm_suballoc_free - Free a suballocation
 * @suballoc: pointer to the suballocation
 * @fence: fence that signals when suballocation is idle
 *
 * Free the suballocation. The suballocation can be re-used after @fence signals.
 */
void drm_suballoc_free(struct drm_suballoc *suballoc,
                       struct dma_fence *fence)
{
        struct drm_suballoc_manager *sa_manager;

        if (!suballoc)
                return;

        sa_manager = suballoc->manager;

        spin_lock(&sa_manager->wq.lock);
        if (fence && !dma_fence_is_signaled(fence)) {
                u32 idx;

                suballoc->fence = dma_fence_get(fence);
                idx = fence->context & (DRM_SUBALLOC_MAX_QUEUES - 1);
                list_add_tail(&suballoc->flist, &sa_manager->flist[idx]);
        } else {
                drm_suballoc_remove_locked(suballoc);
        }
        wake_up_all_locked(&sa_manager->wq);
        spin_unlock(&sa_manager->wq.lock);
}
EXPORT_SYMBOL(drm_suballoc_free);

#ifdef CONFIG_DEBUG_FS
void drm_suballoc_dump_debug_info(struct drm_suballoc_manager *sa_manager,
                                  struct drm_printer *p,
                                  unsigned long long suballoc_base)
{
        struct drm_suballoc *i;

        spin_lock(&sa_manager->wq.lock);
        list_for_each_entry(i, &sa_manager->olist, olist) {
                unsigned long long soffset = i->soffset;
                unsigned long long eoffset = i->eoffset;

                if (&i->olist == sa_manager->hole)
                        drm_puts(p, ">");
                else
                        drm_puts(p, " ");

                drm_printf(p, "[0x%010llx 0x%010llx] size %8lld",
                           suballoc_base + soffset, suballoc_base + eoffset,
                           eoffset - soffset);

                if (i->fence)
                        drm_printf(p, " protected by 0x%016llx on context %llu",
                                   (unsigned long long)i->fence->seqno,
                                   (unsigned long long)i->fence->context);

                drm_puts(p, "\n");
        }
        spin_unlock(&sa_manager->wq.lock);
}
EXPORT_SYMBOL(drm_suballoc_dump_debug_info);
#endif
MODULE_AUTHOR("Multiple");
MODULE_DESCRIPTION("Range suballocator helper");
MODULE_LICENSE("Dual MIT/GPL");