/* 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.
 *
 **************************************************************************/
/*
 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 */

#define pr_fmt(fmt) "[TTM] " fmt

#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/shmem_fs.h>
#include <linux/file.h>
#include <drm/drm_cache.h>
#include <drm/ttm/ttm_bo_driver.h>

#include "ttm_module.h"

static unsigned long ttm_pages_limit;

MODULE_PARM_DESC(pages_limit, "Limit for the allocated pages");
module_param_named(pages_limit, ttm_pages_limit, ulong, 0644);

static unsigned long ttm_dma32_pages_limit;

MODULE_PARM_DESC(dma32_pages_limit, "Limit for the allocated DMA32 pages");
module_param_named(dma32_pages_limit, ttm_dma32_pages_limit, ulong, 0644);

static atomic_long_t ttm_pages_allocated;
static atomic_long_t ttm_dma32_pages_allocated;

/*
 * Allocates a ttm structure for the given BO.
 */
int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc)
{
        struct ttm_device *bdev = bo->bdev;
        uint32_t page_flags = 0;

        dma_resv_assert_held(bo->base.resv);

        if (bo->ttm)
                return 0;

        switch (bo->type) {
        case ttm_bo_type_device:
                if (zero_alloc)
                        page_flags |= TTM_PAGE_FLAG_ZERO_ALLOC;
                break;
        case ttm_bo_type_kernel:
                break;
        case ttm_bo_type_sg:
                page_flags |= TTM_PAGE_FLAG_SG;
                break;
        default:
                pr_err("Illegal buffer object type\n");
                return -EINVAL;
        }

        bo->ttm = bdev->funcs->ttm_tt_create(bo, page_flags);
        if (unlikely(bo->ttm == NULL))
                return -ENOMEM;

        return 0;
}

/*
 * Allocates storage for pointers to the pages that back the ttm.
 */
static int ttm_tt_alloc_page_directory(struct ttm_tt *ttm)
{
        ttm->pages = kvmalloc_array(ttm->num_pages, sizeof(void*),
                        GFP_KERNEL | __GFP_ZERO);
        if (!ttm->pages)
                return -ENOMEM;
        return 0;
}

static int ttm_dma_tt_alloc_page_directory(struct ttm_tt *ttm)
{
        ttm->pages = kvmalloc_array(ttm->num_pages,
                                    sizeof(*ttm->pages) +
                                    sizeof(*ttm->dma_address),
                                    GFP_KERNEL | __GFP_ZERO);
        if (!ttm->pages)
                return -ENOMEM;

        ttm->dma_address = (void *)(ttm->pages + ttm->num_pages);
        return 0;
}

static int ttm_sg_tt_alloc_page_directory(struct ttm_tt *ttm)
{
        ttm->dma_address = kvmalloc_array(ttm->num_pages,
                                          sizeof(*ttm->dma_address),
                                          GFP_KERNEL | __GFP_ZERO);
        if (!ttm->dma_address)
                return -ENOMEM;
        return 0;
}

void ttm_tt_destroy_common(struct ttm_device *bdev, struct ttm_tt *ttm)
{
        ttm_tt_unpopulate(bdev, ttm);

        if (ttm->swap_storage)
                fput(ttm->swap_storage);

        ttm->swap_storage = NULL;
}
EXPORT_SYMBOL(ttm_tt_destroy_common);

void ttm_tt_destroy(struct ttm_device *bdev, struct ttm_tt *ttm)
{
        bdev->funcs->ttm_tt_destroy(bdev, ttm);
}

static void ttm_tt_init_fields(struct ttm_tt *ttm,
                               struct ttm_buffer_object *bo,
                               uint32_t page_flags,
                               enum ttm_caching caching)
{
        ttm->num_pages = PAGE_ALIGN(bo->base.size) >> PAGE_SHIFT;
        ttm->caching = ttm_cached;
        ttm->page_flags = page_flags;
        ttm->dma_address = NULL;
        ttm->swap_storage = NULL;
        ttm->sg = bo->sg;
        ttm->caching = caching;
}

int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
                uint32_t page_flags, enum ttm_caching caching)
{
        ttm_tt_init_fields(ttm, bo, page_flags, caching);

        if (ttm_tt_alloc_page_directory(ttm)) {
                pr_err("Failed allocating page table\n");
                return -ENOMEM;
        }
        return 0;
}
EXPORT_SYMBOL(ttm_tt_init);

void ttm_tt_fini(struct ttm_tt *ttm)
{
        if (ttm->pages)
                kvfree(ttm->pages);
        else
                kvfree(ttm->dma_address);
        ttm->pages = NULL;
        ttm->dma_address = NULL;
}
EXPORT_SYMBOL(ttm_tt_fini);

int ttm_sg_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
                   uint32_t page_flags, enum ttm_caching caching)
{
        int ret;

        ttm_tt_init_fields(ttm, bo, page_flags, caching);

        if (page_flags & TTM_PAGE_FLAG_SG)
                ret = ttm_sg_tt_alloc_page_directory(ttm);
        else
                ret = ttm_dma_tt_alloc_page_directory(ttm);
        if (ret) {
                pr_err("Failed allocating page table\n");
                return -ENOMEM;
        }
        return 0;
}
EXPORT_SYMBOL(ttm_sg_tt_init);

int ttm_tt_swapin(struct ttm_tt *ttm)
{
        struct address_space *swap_space;
        struct file *swap_storage;
        struct page *from_page;
        struct page *to_page;
        gfp_t gfp_mask;
        int i, ret;

        swap_storage = ttm->swap_storage;
        BUG_ON(swap_storage == NULL);

        swap_space = swap_storage->f_mapping;
        gfp_mask = mapping_gfp_mask(swap_space);

        for (i = 0; i < ttm->num_pages; ++i) {
                from_page = shmem_read_mapping_page_gfp(swap_space, i,
                                                        gfp_mask);
                if (IS_ERR(from_page)) {
                        ret = PTR_ERR(from_page);
                        goto out_err;
                }
                to_page = ttm->pages[i];
                if (unlikely(to_page == NULL)) {
                        ret = -ENOMEM;
                        goto out_err;
                }

                copy_highpage(to_page, from_page);
                put_page(from_page);
        }

        fput(swap_storage);
        ttm->swap_storage = NULL;
        ttm->page_flags &= ~TTM_PAGE_FLAG_SWAPPED;

        return 0;

out_err:
        return ret;
}

/**
 * ttm_tt_swapout - swap out tt object
 *
 * @bdev: TTM device structure.
 * @ttm: The struct ttm_tt.
 * @gfp_flags: Flags to use for memory allocation.
 *
 * Swapout a TT object to a shmem_file, return number of pages swapped out or
 * negative error code.
 */
int ttm_tt_swapout(struct ttm_device *bdev, struct ttm_tt *ttm,
                   gfp_t gfp_flags)
{
        loff_t size = (loff_t)ttm->num_pages << PAGE_SHIFT;
        struct address_space *swap_space;
        struct file *swap_storage;
        struct page *from_page;
        struct page *to_page;
        int i, ret;

        swap_storage = shmem_file_setup("ttm swap", size, 0);
        if (IS_ERR(swap_storage)) {
                pr_err("Failed allocating swap storage\n");
                return PTR_ERR(swap_storage);
        }

        swap_space = swap_storage->f_mapping;
        gfp_flags &= mapping_gfp_mask(swap_space);

        for (i = 0; i < ttm->num_pages; ++i) {
                from_page = ttm->pages[i];
                if (unlikely(from_page == NULL))
                        continue;

                to_page = shmem_read_mapping_page_gfp(swap_space, i, gfp_flags);
                if (IS_ERR(to_page)) {
                        ret = PTR_ERR(to_page);
                        goto out_err;
                }
                copy_highpage(to_page, from_page);
                set_page_dirty(to_page);
                mark_page_accessed(to_page);
                put_page(to_page);
        }

        ttm_tt_unpopulate(bdev, ttm);
        ttm->swap_storage = swap_storage;
        ttm->page_flags |= TTM_PAGE_FLAG_SWAPPED;

        return ttm->num_pages;

out_err:
        fput(swap_storage);

        return ret;
}

static void ttm_tt_add_mapping(struct ttm_device *bdev, struct ttm_tt *ttm)
{
        pgoff_t i;

        if (ttm->page_flags & TTM_PAGE_FLAG_SG)
                return;

        for (i = 0; i < ttm->num_pages; ++i)
                ttm->pages[i]->mapping = bdev->dev_mapping;
}

int ttm_tt_populate(struct ttm_device *bdev,
                    struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
{
        int ret;

        if (!ttm)
                return -EINVAL;

        if (ttm_tt_is_populated(ttm))
                return 0;

        if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
                atomic_long_add(ttm->num_pages, &ttm_pages_allocated);
                if (bdev->pool.use_dma32)
                        atomic_long_add(ttm->num_pages,
                                        &ttm_dma32_pages_allocated);
        }

        while (atomic_long_read(&ttm_pages_allocated) > ttm_pages_limit ||
               atomic_long_read(&ttm_dma32_pages_allocated) >
               ttm_dma32_pages_limit) {

                ret = ttm_global_swapout(ctx, GFP_KERNEL);
                if (ret == 0)
                        break;
                if (ret < 0)
                        goto error;
        }

        if (bdev->funcs->ttm_tt_populate)
                ret = bdev->funcs->ttm_tt_populate(bdev, ttm, ctx);
        else
                ret = ttm_pool_alloc(&bdev->pool, ttm, ctx);
        if (ret)
                goto error;

        ttm_tt_add_mapping(bdev, ttm);
        ttm->page_flags |= TTM_PAGE_FLAG_PRIV_POPULATED;
        if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
                ret = ttm_tt_swapin(ttm);
                if (unlikely(ret != 0)) {
                        ttm_tt_unpopulate(bdev, ttm);
                        return ret;
                }
        }

        return 0;

error:
        if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
                atomic_long_sub(ttm->num_pages, &ttm_pages_allocated);
                if (bdev->pool.use_dma32)
                        atomic_long_sub(ttm->num_pages,
                                        &ttm_dma32_pages_allocated);
        }
        return ret;
}
EXPORT_SYMBOL(ttm_tt_populate);

static void ttm_tt_clear_mapping(struct ttm_tt *ttm)
{
        pgoff_t i;
        struct page **page = ttm->pages;

        if (ttm->page_flags & TTM_PAGE_FLAG_SG)
                return;

        for (i = 0; i < ttm->num_pages; ++i) {
                (*page)->mapping = NULL;
                (*page++)->index = 0;
        }
}

void ttm_tt_unpopulate(struct ttm_device *bdev, struct ttm_tt *ttm)
{
        if (!ttm_tt_is_populated(ttm))
                return;

        ttm_tt_clear_mapping(ttm);
        if (bdev->funcs->ttm_tt_unpopulate)
                bdev->funcs->ttm_tt_unpopulate(bdev, ttm);
        else
                ttm_pool_free(&bdev->pool, ttm);

        if (!(ttm->page_flags & TTM_PAGE_FLAG_SG)) {
                atomic_long_sub(ttm->num_pages, &ttm_pages_allocated);
                if (bdev->pool.use_dma32)
                        atomic_long_sub(ttm->num_pages,
                                        &ttm_dma32_pages_allocated);
        }

        ttm->page_flags &= ~TTM_PAGE_FLAG_PRIV_POPULATED;
}

#ifdef CONFIG_DEBUG_FS

/* Test the shrinker functions and dump the result */
static int ttm_tt_debugfs_shrink_show(struct seq_file *m, void *data)
{
        struct ttm_operation_ctx ctx = { false, false };

        seq_printf(m, "%d\n", ttm_global_swapout(&ctx, GFP_KERNEL));
        return 0;
}
DEFINE_SHOW_ATTRIBUTE(ttm_tt_debugfs_shrink);

#endif


/*
 * ttm_tt_mgr_init - register with the MM shrinker
 *
 * Register with the MM shrinker for swapping out BOs.
 */
void ttm_tt_mgr_init(unsigned long num_pages, unsigned long num_dma32_pages)
{
#ifdef CONFIG_DEBUG_FS
        debugfs_create_file("tt_shrink", 0400, ttm_debugfs_root, NULL,
                            &ttm_tt_debugfs_shrink_fops);
#endif

        if (!ttm_pages_limit)
                ttm_pages_limit = num_pages;

        if (!ttm_dma32_pages_limit)
                ttm_dma32_pages_limit = num_dma32_pages;
}

static void ttm_kmap_iter_tt_map_local(struct ttm_kmap_iter *iter,
                                       struct dma_buf_map *dmap,
                                       pgoff_t i)
{
        struct ttm_kmap_iter_tt *iter_tt =
                container_of(iter, typeof(*iter_tt), base);

        dma_buf_map_set_vaddr(dmap, kmap_local_page_prot(iter_tt->tt->pages[i],
                                                         iter_tt->prot));
}

static void ttm_kmap_iter_tt_unmap_local(struct ttm_kmap_iter *iter,
                                         struct dma_buf_map *map)
{
        kunmap_local(map->vaddr);
}

static const struct ttm_kmap_iter_ops ttm_kmap_iter_tt_ops = {
        .map_local = ttm_kmap_iter_tt_map_local,
        .unmap_local = ttm_kmap_iter_tt_unmap_local,
        .maps_tt = true,
};

/**
 * ttm_kmap_iter_tt_init - Initialize a struct ttm_kmap_iter_tt
 * @iter_tt: The struct ttm_kmap_iter_tt to initialize.
 * @tt: Struct ttm_tt holding page pointers of the struct ttm_resource.
 *
 * Return: Pointer to the embedded struct ttm_kmap_iter.
 */
struct ttm_kmap_iter *
ttm_kmap_iter_tt_init(struct ttm_kmap_iter_tt *iter_tt,
                      struct ttm_tt *tt)
{
        iter_tt->base.ops = &ttm_kmap_iter_tt_ops;
        iter_tt->tt = tt;
        if (tt)
                iter_tt->prot = ttm_prot_from_caching(tt->caching, PAGE_KERNEL);
        else
                iter_tt->prot = PAGE_KERNEL;

        return &iter_tt->base;
}
EXPORT_SYMBOL(ttm_kmap_iter_tt_init);