/*
 * Copyright 2020 Advanced Micro Devices, Inc.
 *
 * 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 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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: Christian König
 */

#include <linux/debugfs.h>
#include <linux/export.h>
#include <linux/io-mapping.h>
#include <linux/iosys-map.h>
#include <linux/scatterlist.h>
#include <linux/cgroup_dmem.h>

#include <drm/ttm/ttm_bo.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/ttm/ttm_resource.h>
#include <drm/ttm/ttm_tt.h>

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

/* Detach the cursor from the bulk move list*/
static void
ttm_resource_cursor_clear_bulk(struct ttm_resource_cursor *cursor)
{
        lockdep_assert_held(&cursor->man->bdev->lru_lock);

        cursor->bulk = NULL;
        list_del_init(&cursor->bulk_link);
}

/* Move the cursor to the end of the bulk move list it's in */
static void ttm_resource_cursor_move_bulk_tail(struct ttm_lru_bulk_move *bulk,
                                               struct ttm_resource_cursor *cursor)
{
        struct ttm_lru_bulk_move_pos *pos;

        lockdep_assert_held(&cursor->man->bdev->lru_lock);

        if (WARN_ON_ONCE(bulk != cursor->bulk)) {
                list_del_init(&cursor->bulk_link);
                return;
        }

        pos = &bulk->pos[cursor->mem_type][cursor->priority];
        if (pos->last)
                list_move(&cursor->hitch.link, &pos->last->lru.link);
        ttm_resource_cursor_clear_bulk(cursor);
}

/* Move all cursors attached to a bulk move to its end */
static void ttm_bulk_move_adjust_cursors(struct ttm_lru_bulk_move *bulk)
{
        struct ttm_resource_cursor *cursor, *next;

        list_for_each_entry_safe(cursor, next, &bulk->cursor_list, bulk_link)
                ttm_resource_cursor_move_bulk_tail(bulk, cursor);
}

/* Remove a cursor from an empty bulk move list */
static void ttm_bulk_move_drop_cursors(struct ttm_lru_bulk_move *bulk)
{
        struct ttm_resource_cursor *cursor, *next;

        list_for_each_entry_safe(cursor, next, &bulk->cursor_list, bulk_link)
                ttm_resource_cursor_clear_bulk(cursor);
}

/**
 * ttm_resource_cursor_init() - Initialize a struct ttm_resource_cursor
 * @cursor: The cursor to initialize.
 * @man: The resource manager.
 *
 * Initialize the cursor before using it for iteration.
 */
void ttm_resource_cursor_init(struct ttm_resource_cursor *cursor,
                              struct ttm_resource_manager *man)
{
        cursor->priority = 0;
        cursor->man = man;
        ttm_lru_item_init(&cursor->hitch, TTM_LRU_HITCH);
        INIT_LIST_HEAD(&cursor->bulk_link);
        INIT_LIST_HEAD(&cursor->hitch.link);
}

/**
 * ttm_resource_cursor_fini() - Finalize the LRU list cursor usage
 * @cursor: The struct ttm_resource_cursor to finalize.
 *
 * The function pulls the LRU list cursor off any lists it was previusly
 * attached to. Needs to be called with the LRU lock held. The function
 * can be called multiple times after eachother.
 */
void ttm_resource_cursor_fini(struct ttm_resource_cursor *cursor)
{
        lockdep_assert_held(&cursor->man->bdev->lru_lock);
        list_del_init(&cursor->hitch.link);
        ttm_resource_cursor_clear_bulk(cursor);
}

/**
 * ttm_lru_bulk_move_init - initialize a bulk move structure
 * @bulk: the structure to init
 *
 * For now just memset the structure to zero.
 */
void ttm_lru_bulk_move_init(struct ttm_lru_bulk_move *bulk)
{
        memset(bulk, 0, sizeof(*bulk));
        INIT_LIST_HEAD(&bulk->cursor_list);
}
EXPORT_SYMBOL(ttm_lru_bulk_move_init);

/**
 * ttm_lru_bulk_move_fini - finalize a bulk move structure
 * @bdev: The struct ttm_device
 * @bulk: the structure to finalize
 *
 * Sanity checks that bulk moves don't have any
 * resources left and hence no cursors attached.
 */
void ttm_lru_bulk_move_fini(struct ttm_device *bdev,
                            struct ttm_lru_bulk_move *bulk)
{
        spin_lock(&bdev->lru_lock);
        ttm_bulk_move_drop_cursors(bulk);
        spin_unlock(&bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_lru_bulk_move_fini);

/**
 * ttm_lru_bulk_move_tail - bulk move range of resources to the LRU tail.
 *
 * @bulk: bulk move structure
 *
 * Bulk move BOs to the LRU tail, only valid to use when driver makes sure that
 * resource order never changes. Should be called with &ttm_device.lru_lock held.
 */
void ttm_lru_bulk_move_tail(struct ttm_lru_bulk_move *bulk)
{
        unsigned i, j;

        ttm_bulk_move_adjust_cursors(bulk);
        for (i = 0; i < TTM_NUM_MEM_TYPES; ++i) {
                for (j = 0; j < TTM_MAX_BO_PRIORITY; ++j) {
                        struct ttm_lru_bulk_move_pos *pos = &bulk->pos[i][j];
                        struct ttm_resource_manager *man;

                        if (!pos->first)
                                continue;

                        lockdep_assert_held(&pos->first->bo->bdev->lru_lock);
                        dma_resv_assert_held(pos->first->bo->base.resv);
                        dma_resv_assert_held(pos->last->bo->base.resv);

                        man = ttm_manager_type(pos->first->bo->bdev, i);
                        list_bulk_move_tail(&man->lru[j], &pos->first->lru.link,
                                            &pos->last->lru.link);
                }
        }
}
EXPORT_SYMBOL(ttm_lru_bulk_move_tail);

/* Return the bulk move pos object for this resource */
static struct ttm_lru_bulk_move_pos *
ttm_lru_bulk_move_pos(struct ttm_lru_bulk_move *bulk, struct ttm_resource *res)
{
        return &bulk->pos[res->mem_type][res->bo->priority];
}

/* Return the previous resource on the list (skip over non-resource list items) */
static struct ttm_resource *ttm_lru_prev_res(struct ttm_resource *cur)
{
        struct ttm_lru_item *lru = &cur->lru;

        do {
                lru = list_prev_entry(lru, link);
        } while (!ttm_lru_item_is_res(lru));

        return ttm_lru_item_to_res(lru);
}

/* Return the next resource on the list (skip over non-resource list items) */
static struct ttm_resource *ttm_lru_next_res(struct ttm_resource *cur)
{
        struct ttm_lru_item *lru = &cur->lru;

        do {
                lru = list_next_entry(lru, link);
        } while (!ttm_lru_item_is_res(lru));

        return ttm_lru_item_to_res(lru);
}

/* Move the resource to the tail of the bulk move range */
static void ttm_lru_bulk_move_pos_tail(struct ttm_lru_bulk_move_pos *pos,
                                       struct ttm_resource *res)
{
        if (pos->last != res) {
                if (pos->first == res)
                        pos->first = ttm_lru_next_res(res);
                list_move(&res->lru.link, &pos->last->lru.link);
                pos->last = res;
        }
}

/* Add the resource to a bulk_move cursor */
static void ttm_lru_bulk_move_add(struct ttm_lru_bulk_move *bulk,
                                  struct ttm_resource *res)
{
        struct ttm_lru_bulk_move_pos *pos = ttm_lru_bulk_move_pos(bulk, res);

        if (!pos->first) {
                pos->first = res;
                pos->last = res;
        } else {
                WARN_ON(pos->first->bo->base.resv != res->bo->base.resv);
                ttm_lru_bulk_move_pos_tail(pos, res);
        }
}

/* Remove the resource from a bulk_move range */
static void ttm_lru_bulk_move_del(struct ttm_lru_bulk_move *bulk,
                                  struct ttm_resource *res)
{
        struct ttm_lru_bulk_move_pos *pos = ttm_lru_bulk_move_pos(bulk, res);

        if (unlikely(WARN_ON(!pos->first || !pos->last) ||
                     (pos->first == res && pos->last == res))) {
                pos->first = NULL;
                pos->last = NULL;
        } else if (pos->first == res) {
                pos->first = ttm_lru_next_res(res);
        } else if (pos->last == res) {
                pos->last = ttm_lru_prev_res(res);
        } else {
                list_move(&res->lru.link, &pos->last->lru.link);
        }
}

static bool ttm_resource_is_swapped(struct ttm_resource *res, struct ttm_buffer_object *bo)
{
        /*
         * Take care when creating a new resource for a bo, that it is not considered
         * swapped if it's not the current resource for the bo and is thus logically
         * associated with the ttm_tt. Think a VRAM resource created to move a
         * swapped-out bo to VRAM.
         */
        if (bo->resource != res || !bo->ttm)
                return false;

        dma_resv_assert_held(bo->base.resv);
        return ttm_tt_is_swapped(bo->ttm);
}

static bool ttm_resource_unevictable(struct ttm_resource *res, struct ttm_buffer_object *bo)
{
        return bo->pin_count || ttm_resource_is_swapped(res, bo);
}

/* Add the resource to a bulk move if the BO is configured for it */
void ttm_resource_add_bulk_move(struct ttm_resource *res,
                                struct ttm_buffer_object *bo)
{
        if (bo->bulk_move && !ttm_resource_unevictable(res, bo))
                ttm_lru_bulk_move_add(bo->bulk_move, res);
}

/* Remove the resource from a bulk move if the BO is configured for it */
void ttm_resource_del_bulk_move(struct ttm_resource *res,
                                struct ttm_buffer_object *bo)
{
        if (bo->bulk_move && !ttm_resource_unevictable(res, bo))
                ttm_lru_bulk_move_del(bo->bulk_move, res);
}

/* Move a resource to the LRU or bulk tail */
void ttm_resource_move_to_lru_tail(struct ttm_resource *res)
{
        struct ttm_buffer_object *bo = res->bo;
        struct ttm_device *bdev = bo->bdev;

        lockdep_assert_held(&bo->bdev->lru_lock);

        if (ttm_resource_unevictable(res, bo)) {
                list_move_tail(&res->lru.link, &bdev->unevictable);

        } else if (bo->bulk_move) {
                struct ttm_lru_bulk_move_pos *pos =
                        ttm_lru_bulk_move_pos(bo->bulk_move, res);

                ttm_lru_bulk_move_pos_tail(pos, res);
        } else {
                struct ttm_resource_manager *man;

                man = ttm_manager_type(bdev, res->mem_type);
                list_move_tail(&res->lru.link, &man->lru[bo->priority]);
        }
}

/**
 * ttm_resource_init - resource object constructure
 * @bo: buffer object this resources is allocated for
 * @place: placement of the resource
 * @res: the resource object to inistilize
 *
 * Initialize a new resource object. Counterpart of ttm_resource_fini().
 */
void ttm_resource_init(struct ttm_buffer_object *bo,
                       const struct ttm_place *place,
                       struct ttm_resource *res)
{
        struct ttm_resource_manager *man;

        res->start = 0;
        res->size = bo->base.size;
        res->mem_type = place->mem_type;
        res->placement = place->flags;
        res->bus.addr = NULL;
        res->bus.offset = 0;
        res->bus.is_iomem = false;
        res->bus.caching = ttm_cached;
        res->bo = bo;

        man = ttm_manager_type(bo->bdev, place->mem_type);
        spin_lock(&bo->bdev->lru_lock);
        if (ttm_resource_unevictable(res, bo))
                list_add_tail(&res->lru.link, &bo->bdev->unevictable);
        else
                list_add_tail(&res->lru.link, &man->lru[bo->priority]);
        man->usage += res->size;
        spin_unlock(&bo->bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_resource_init);

/**
 * ttm_resource_fini - resource destructor
 * @man: the resource manager this resource belongs to
 * @res: the resource to clean up
 *
 * Should be used by resource manager backends to clean up the TTM resource
 * objects before freeing the underlying structure. Makes sure the resource is
 * removed from the LRU before destruction.
 * Counterpart of ttm_resource_init().
 */
void ttm_resource_fini(struct ttm_resource_manager *man,
                       struct ttm_resource *res)
{
        struct ttm_device *bdev = man->bdev;

        spin_lock(&bdev->lru_lock);
        list_del_init(&res->lru.link);
        man->usage -= res->size;
        spin_unlock(&bdev->lru_lock);
}
EXPORT_SYMBOL(ttm_resource_fini);

int ttm_resource_alloc(struct ttm_buffer_object *bo,
                       const struct ttm_place *place,
                       struct ttm_resource **res_ptr,
                       struct dmem_cgroup_pool_state **ret_limit_pool)
{
        struct ttm_resource_manager *man =
                ttm_manager_type(bo->bdev, place->mem_type);
        struct dmem_cgroup_pool_state *pool = NULL;
        int ret;

        if (man->cg) {
                ret = dmem_cgroup_try_charge(man->cg, bo->base.size, &pool, ret_limit_pool);
                if (ret)
                        return ret;
        }

        ret = man->func->alloc(man, bo, place, res_ptr);
        if (ret) {
                if (pool)
                        dmem_cgroup_uncharge(pool, bo->base.size);
                return ret;
        }

        (*res_ptr)->css = pool;

        spin_lock(&bo->bdev->lru_lock);
        ttm_resource_add_bulk_move(*res_ptr, bo);
        spin_unlock(&bo->bdev->lru_lock);
        return 0;
}
EXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_resource_alloc);

void ttm_resource_free(struct ttm_buffer_object *bo, struct ttm_resource **res)
{
        struct ttm_resource_manager *man;
        struct dmem_cgroup_pool_state *pool;

        if (!*res)
                return;

        spin_lock(&bo->bdev->lru_lock);
        ttm_resource_del_bulk_move(*res, bo);
        spin_unlock(&bo->bdev->lru_lock);

        pool = (*res)->css;
        man = ttm_manager_type(bo->bdev, (*res)->mem_type);
        man->func->free(man, *res);
        *res = NULL;
        if (man->cg)
                dmem_cgroup_uncharge(pool, bo->base.size);
}
EXPORT_SYMBOL(ttm_resource_free);

/**
 * ttm_resource_intersects - test for intersection
 *
 * @bdev: TTM device structure
 * @res: The resource to test
 * @place: The placement to test
 * @size: How many bytes the new allocation needs.
 *
 * Test if @res intersects with @place and @size. Used for testing if evictions
 * are valueable or not.
 *
 * Returns true if the res placement intersects with @place and @size.
 */
bool ttm_resource_intersects(struct ttm_device *bdev,
                             struct ttm_resource *res,
                             const struct ttm_place *place,
                             size_t size)
{
        struct ttm_resource_manager *man;

        man = ttm_manager_type(bdev, res->mem_type);
        if (!place || !man->func->intersects)
                return true;

        return man->func->intersects(man, res, place, size);
}

/**
 * ttm_resource_compatible - check if resource is compatible with placement
 *
 * @res: the resource to check
 * @placement: the placement to check against
 * @evicting: true if the caller is doing evictions
 *
 * Returns true if the placement is compatible.
 */
bool ttm_resource_compatible(struct ttm_resource *res,
                             struct ttm_placement *placement,
                             bool evicting)
{
        struct ttm_buffer_object *bo = res->bo;
        struct ttm_device *bdev = bo->bdev;
        unsigned i;

        if (res->placement & TTM_PL_FLAG_TEMPORARY)
                return false;

        for (i = 0; i < placement->num_placement; i++) {
                const struct ttm_place *place = &placement->placement[i];
                struct ttm_resource_manager *man;

                if (res->mem_type != place->mem_type)
                        continue;

                if (place->flags & (evicting ? TTM_PL_FLAG_DESIRED :
                                    TTM_PL_FLAG_FALLBACK))
                        continue;

                if (place->flags & TTM_PL_FLAG_CONTIGUOUS &&
                    !(res->placement & TTM_PL_FLAG_CONTIGUOUS))
                        continue;

                man = ttm_manager_type(bdev, res->mem_type);
                if (man->func->compatible &&
                    !man->func->compatible(man, res, place, bo->base.size))
                        continue;

                return true;
        }
        return false;
}

void ttm_resource_set_bo(struct ttm_resource *res,
                         struct ttm_buffer_object *bo)
{
        spin_lock(&bo->bdev->lru_lock);
        res->bo = bo;
        spin_unlock(&bo->bdev->lru_lock);
}

/**
 * ttm_resource_manager_init
 *
 * @man: memory manager object to init
 * @bdev: ttm device this manager belongs to
 * @size: size of managed resources in arbitrary units
 *
 * Initialise core parts of a manager object.
 */
void ttm_resource_manager_init(struct ttm_resource_manager *man,
                               struct ttm_device *bdev,
                               uint64_t size)
{
        unsigned i;

        man->bdev = bdev;
        man->size = size;
        man->usage = 0;

        for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i)
                INIT_LIST_HEAD(&man->lru[i]);
        spin_lock_init(&man->eviction_lock);
        for (i = 0; i < TTM_NUM_MOVE_FENCES; i++)
                man->eviction_fences[i] = NULL;
}
EXPORT_SYMBOL(ttm_resource_manager_init);

/*
 * ttm_resource_manager_evict_all
 *
 * @bdev - device to use
 * @man - manager to use
 *
 * Evict all the objects out of a memory manager until it is empty.
 * Part of memory manager cleanup sequence.
 */
int ttm_resource_manager_evict_all(struct ttm_device *bdev,
                                   struct ttm_resource_manager *man)
{
        struct ttm_operation_ctx ctx = { };
        struct dma_fence *fence;
        int ret, i;

        do {
                ret = ttm_bo_evict_first(bdev, man, &ctx);
                cond_resched();
        } while (!ret);

        if (ret && ret != -ENOENT)
                return ret;

        ret = 0;

        spin_lock(&man->eviction_lock);
        for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) {
                fence = man->eviction_fences[i];
                if (fence && !dma_fence_is_signaled(fence)) {
                        dma_fence_get(fence);
                        spin_unlock(&man->eviction_lock);
                        ret = dma_fence_wait(fence, false);
                        dma_fence_put(fence);
                        if (ret)
                                return ret;
                        spin_lock(&man->eviction_lock);
                }
        }
        spin_unlock(&man->eviction_lock);

        return ret;
}
EXPORT_SYMBOL(ttm_resource_manager_evict_all);

/**
 * ttm_resource_manager_usage
 *
 * @man: A memory manager object.
 *
 * Return how many resources are currently used.
 */
uint64_t ttm_resource_manager_usage(struct ttm_resource_manager *man)
{
        uint64_t usage;

        if (WARN_ON_ONCE(!man->bdev))
                return 0;

        spin_lock(&man->bdev->lru_lock);
        usage = man->usage;
        spin_unlock(&man->bdev->lru_lock);
        return usage;
}
EXPORT_SYMBOL(ttm_resource_manager_usage);

/**
 * ttm_resource_manager_debug
 *
 * @man: manager type to dump.
 * @p: printer to use for debug.
 */
void ttm_resource_manager_debug(struct ttm_resource_manager *man,
                                struct drm_printer *p)
{
        drm_printf(p, "  use_type: %d\n", man->use_type);
        drm_printf(p, "  use_tt: %d\n", man->use_tt);
        drm_printf(p, "  size: %llu\n", man->size);
        drm_printf(p, "  usage: %llu\n", ttm_resource_manager_usage(man));
        if (man->func->debug)
                man->func->debug(man, p);
}
EXPORT_SYMBOL(ttm_resource_manager_debug);

static void
ttm_resource_cursor_check_bulk(struct ttm_resource_cursor *cursor,
                               struct ttm_lru_item *next_lru)
{
        struct ttm_resource *next = ttm_lru_item_to_res(next_lru);
        struct ttm_lru_bulk_move *bulk;

        lockdep_assert_held(&cursor->man->bdev->lru_lock);

        bulk = next->bo->bulk_move;

        if (cursor->bulk != bulk) {
                if (bulk) {
                        list_move_tail(&cursor->bulk_link, &bulk->cursor_list);
                        cursor->mem_type = next->mem_type;
                } else {
                        list_del_init(&cursor->bulk_link);
                }
                cursor->bulk = bulk;
        }
}

/**
 * ttm_resource_manager_first() - Start iterating over the resources
 * of a resource manager
 * @cursor: cursor to record the position
 *
 * Initializes the cursor and starts iterating. When done iterating,
 * the caller must explicitly call ttm_resource_cursor_fini().
 *
 * Return: The first resource from the resource manager.
 */
struct ttm_resource *
ttm_resource_manager_first(struct ttm_resource_cursor *cursor)
{
        struct ttm_resource_manager *man = cursor->man;

        if (WARN_ON_ONCE(!man))
                return NULL;

        lockdep_assert_held(&man->bdev->lru_lock);

        list_move(&cursor->hitch.link, &man->lru[cursor->priority]);
        return ttm_resource_manager_next(cursor);
}

/**
 * ttm_resource_manager_next() - Continue iterating over the resource manager
 * resources
 * @cursor: cursor to record the position
 *
 * Return: the next resource from the resource manager.
 */
struct ttm_resource *
ttm_resource_manager_next(struct ttm_resource_cursor *cursor)
{
        struct ttm_resource_manager *man = cursor->man;
        struct ttm_lru_item *lru;

        lockdep_assert_held(&man->bdev->lru_lock);

        for (;;) {
                lru = &cursor->hitch;
                list_for_each_entry_continue(lru, &man->lru[cursor->priority], link) {
                        if (ttm_lru_item_is_res(lru)) {
                                ttm_resource_cursor_check_bulk(cursor, lru);
                                list_move(&cursor->hitch.link, &lru->link);
                                return ttm_lru_item_to_res(lru);
                        }
                }

                if (++cursor->priority >= TTM_MAX_BO_PRIORITY)
                        break;

                list_move(&cursor->hitch.link, &man->lru[cursor->priority]);
                ttm_resource_cursor_clear_bulk(cursor);
        }

        return NULL;
}

/**
 * ttm_lru_first_res_or_null() - Return the first resource on an lru list
 * @head: The list head of the lru list.
 *
 * Return: Pointer to the first resource on the lru list or NULL if
 * there is none.
 */
struct ttm_resource *ttm_lru_first_res_or_null(struct list_head *head)
{
        struct ttm_lru_item *lru;

        list_for_each_entry(lru, head, link) {
                if (ttm_lru_item_is_res(lru))
                        return ttm_lru_item_to_res(lru);
        }

        return NULL;
}

static void ttm_kmap_iter_iomap_map_local(struct ttm_kmap_iter *iter,
                                          struct iosys_map *dmap,
                                          pgoff_t i)
{
        struct ttm_kmap_iter_iomap *iter_io =
                container_of(iter, typeof(*iter_io), base);
        void __iomem *addr;

retry:
        while (i >= iter_io->cache.end) {
                iter_io->cache.sg = iter_io->cache.sg ?
                        sg_next(iter_io->cache.sg) : iter_io->st->sgl;
                iter_io->cache.i = iter_io->cache.end;
                iter_io->cache.end += sg_dma_len(iter_io->cache.sg) >>
                        PAGE_SHIFT;
                iter_io->cache.offs = sg_dma_address(iter_io->cache.sg) -
                        iter_io->start;
        }

        if (i < iter_io->cache.i) {
                iter_io->cache.end = 0;
                iter_io->cache.sg = NULL;
                goto retry;
        }

        addr = io_mapping_map_local_wc(iter_io->iomap, iter_io->cache.offs +
                                       (((resource_size_t)i - iter_io->cache.i)
                                        << PAGE_SHIFT));
        iosys_map_set_vaddr_iomem(dmap, addr);
}

static void ttm_kmap_iter_iomap_unmap_local(struct ttm_kmap_iter *iter,
                                            struct iosys_map *map)
{
        io_mapping_unmap_local(map->vaddr_iomem);
}

static const struct ttm_kmap_iter_ops ttm_kmap_iter_io_ops = {
        .map_local =  ttm_kmap_iter_iomap_map_local,
        .unmap_local = ttm_kmap_iter_iomap_unmap_local,
        .maps_tt = false,
};

/**
 * ttm_kmap_iter_iomap_init - Initialize a struct ttm_kmap_iter_iomap
 * @iter_io: The struct ttm_kmap_iter_iomap to initialize.
 * @iomap: The struct io_mapping representing the underlying linear io_memory.
 * @st: sg_table into @iomap, representing the memory of the struct
 * ttm_resource.
 * @start: Offset that needs to be subtracted from @st to make
 * sg_dma_address(st->sgl) - @start == 0 for @iomap start.
 *
 * Return: Pointer to the embedded struct ttm_kmap_iter.
 */
struct ttm_kmap_iter *
ttm_kmap_iter_iomap_init(struct ttm_kmap_iter_iomap *iter_io,
                         struct io_mapping *iomap,
                         struct sg_table *st,
                         resource_size_t start)
{
        iter_io->base.ops = &ttm_kmap_iter_io_ops;
        iter_io->iomap = iomap;
        iter_io->st = st;
        iter_io->start = start;
        memset(&iter_io->cache, 0, sizeof(iter_io->cache));

        return &iter_io->base;
}
EXPORT_SYMBOL(ttm_kmap_iter_iomap_init);

/**
 * DOC: Linear io iterator
 *
 * This code should die in the not too near future. Best would be if we could
 * make io-mapping use memremap for all io memory, and have memremap
 * implement a kmap_local functionality. We could then strip a huge amount of
 * code. These linear io iterators are implemented to mimic old functionality,
 * and they don't use kmap_local semantics at all internally. Rather ioremap or
 * friends, and at least on 32-bit they add global TLB flushes and points
 * of failure.
 */

static void ttm_kmap_iter_linear_io_map_local(struct ttm_kmap_iter *iter,
                                              struct iosys_map *dmap,
                                              pgoff_t i)
{
        struct ttm_kmap_iter_linear_io *iter_io =
                container_of(iter, typeof(*iter_io), base);

        *dmap = iter_io->dmap;
        iosys_map_incr(dmap, i * PAGE_SIZE);
}

static const struct ttm_kmap_iter_ops ttm_kmap_iter_linear_io_ops = {
        .map_local =  ttm_kmap_iter_linear_io_map_local,
        .maps_tt = false,
};

/**
 * ttm_kmap_iter_linear_io_init - Initialize an iterator for linear io memory
 * @iter_io: The iterator to initialize
 * @bdev: The TTM device
 * @mem: The ttm resource representing the iomap.
 *
 * This function is for internal TTM use only. It sets up a memcpy kmap iterator
 * pointing at a linear chunk of io memory.
 *
 * Return: A pointer to the embedded struct ttm_kmap_iter or error pointer on
 * failure.
 */
struct ttm_kmap_iter *
ttm_kmap_iter_linear_io_init(struct ttm_kmap_iter_linear_io *iter_io,
                             struct ttm_device *bdev,
                             struct ttm_resource *mem)
{
        int ret;

        ret = ttm_mem_io_reserve(bdev, mem);
        if (ret)
                goto out_err;
        if (!mem->bus.is_iomem) {
                ret = -EINVAL;
                goto out_io_free;
        }

        if (mem->bus.addr) {
                iosys_map_set_vaddr(&iter_io->dmap, mem->bus.addr);
                iter_io->needs_unmap = false;
        } else {
                iter_io->needs_unmap = true;
                memset(&iter_io->dmap, 0, sizeof(iter_io->dmap));
                if (mem->bus.caching == ttm_write_combined)
                        iosys_map_set_vaddr_iomem(&iter_io->dmap,
                                                  ioremap_wc(mem->bus.offset,
                                                             mem->size));
                else if (mem->bus.caching == ttm_cached)
                        iosys_map_set_vaddr(&iter_io->dmap,
                                            memremap(mem->bus.offset, mem->size,
                                                     MEMREMAP_WB |
                                                     MEMREMAP_WT |
                                                     MEMREMAP_WC));

                /* If uncached requested or if mapping cached or wc failed */
                if (iosys_map_is_null(&iter_io->dmap))
                        iosys_map_set_vaddr_iomem(&iter_io->dmap,
                                                  ioremap(mem->bus.offset,
                                                          mem->size));

                if (iosys_map_is_null(&iter_io->dmap)) {
                        ret = -ENOMEM;
                        goto out_io_free;
                }
        }

        iter_io->base.ops = &ttm_kmap_iter_linear_io_ops;
        return &iter_io->base;

out_io_free:
        ttm_mem_io_free(bdev, mem);
out_err:
        return ERR_PTR(ret);
}

/**
 * ttm_kmap_iter_linear_io_fini - Clean up an iterator for linear io memory
 * @iter_io: The iterator to initialize
 * @bdev: The TTM device
 * @mem: The ttm resource representing the iomap.
 *
 * This function is for internal TTM use only. It cleans up a memcpy kmap
 * iterator initialized by ttm_kmap_iter_linear_io_init.
 */
void
ttm_kmap_iter_linear_io_fini(struct ttm_kmap_iter_linear_io *iter_io,
                             struct ttm_device *bdev,
                             struct ttm_resource *mem)
{
        if (iter_io->needs_unmap && iosys_map_is_set(&iter_io->dmap)) {
                if (iter_io->dmap.is_iomem)
                        iounmap(iter_io->dmap.vaddr_iomem);
                else
                        memunmap(iter_io->dmap.vaddr);
        }

        ttm_mem_io_free(bdev, mem);
}

#if defined(CONFIG_DEBUG_FS)

static int ttm_resource_manager_show(struct seq_file *m, void *unused)
{
        struct ttm_resource_manager *man =
                (struct ttm_resource_manager *)m->private;
        struct drm_printer p = drm_seq_file_printer(m);
        ttm_resource_manager_debug(man, &p);
        return 0;
}
DEFINE_SHOW_ATTRIBUTE(ttm_resource_manager);

#endif

/**
 * ttm_resource_manager_create_debugfs - Create debugfs entry for specified
 * resource manager.
 * @man: The TTM resource manager for which the debugfs stats file be creates
 * @parent: debugfs directory in which the file will reside
 * @name: The filename to create.
 *
 * This function setups up a debugfs file that can be used to look
 * at debug statistics of the specified ttm_resource_manager.
 */
void ttm_resource_manager_create_debugfs(struct ttm_resource_manager *man,
                                         struct dentry * parent,
                                         const char *name)
{
#if defined(CONFIG_DEBUG_FS)
        debugfs_create_file(name, 0444, parent, man, &ttm_resource_manager_fops);
#endif
}
EXPORT_SYMBOL(ttm_resource_manager_create_debugfs);