/* SPDX-License-Identifier: GPL-2.0 OR MIT */

/*
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * 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
 */

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

#include <linux/debugfs.h>
#include <linux/export.h>
#include <linux/mm.h>

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

#include "ttm_module.h"
#include "ttm_bo_internal.h"

/*
 * ttm_global_mutex - protecting the global state
 */
static DEFINE_MUTEX(ttm_global_mutex);
static unsigned ttm_glob_use_count;
struct ttm_global ttm_glob;
EXPORT_SYMBOL(ttm_glob);

struct dentry *ttm_debugfs_root;

static void ttm_global_release(void)
{
        struct ttm_global *glob = &ttm_glob;

        mutex_lock(&ttm_global_mutex);
        if (--ttm_glob_use_count > 0)
                goto out;

        ttm_pool_mgr_fini();
        debugfs_remove(ttm_debugfs_root);

        __free_page(glob->dummy_read_page);
        memset(glob, 0, sizeof(*glob));
out:
        mutex_unlock(&ttm_global_mutex);
}

static int ttm_global_init(void)
{
        struct ttm_global *glob = &ttm_glob;
        unsigned long num_pages, num_dma32;
        struct sysinfo si;
        int ret = 0;

        mutex_lock(&ttm_global_mutex);
        if (++ttm_glob_use_count > 1)
                goto out;

        si_meminfo(&si);

        ttm_debugfs_root = debugfs_create_dir("ttm", NULL);
        if (IS_ERR(ttm_debugfs_root)) {
                ttm_debugfs_root = NULL;
        }

        /* Limit the number of pages in the pool to about 50% of the total
         * system memory.
         */
        num_pages = ((u64)si.totalram * si.mem_unit) >> PAGE_SHIFT;
        num_pages /= 2;

        /* But for DMA32 we limit ourself to only use 2GiB maximum. */
        num_dma32 = (u64)(si.totalram - si.totalhigh) * si.mem_unit
                >> PAGE_SHIFT;
        num_dma32 = min(num_dma32, 2UL << (30 - PAGE_SHIFT));

        ttm_pool_mgr_init(num_pages);
        ttm_tt_mgr_init(num_pages, num_dma32);

        glob->dummy_read_page = alloc_page(__GFP_ZERO | GFP_DMA32 |
                                           __GFP_NOWARN);

        /* Retry without GFP_DMA32 for platforms DMA32 is not available */
        if (unlikely(glob->dummy_read_page == NULL)) {
                glob->dummy_read_page = alloc_page(__GFP_ZERO);
                if (unlikely(glob->dummy_read_page == NULL)) {
                        ret = -ENOMEM;
                        goto out;
                }
                pr_warn("Using GFP_DMA32 fallback for dummy_read_page\n");
        }

        INIT_LIST_HEAD(&glob->device_list);
        atomic_set(&glob->bo_count, 0);

        debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root,
                                &glob->bo_count);
out:
        if (ret && ttm_debugfs_root)
                debugfs_remove(ttm_debugfs_root);
        if (ret)
                --ttm_glob_use_count;
        mutex_unlock(&ttm_global_mutex);
        return ret;
}

/**
 * ttm_device_prepare_hibernation - move GTT BOs to shmem for hibernation.
 *
 * @bdev: A pointer to a struct ttm_device to prepare hibernation for.
 *
 * Return: 0 on success, negative number on failure.
 */
int ttm_device_prepare_hibernation(struct ttm_device *bdev)
{
        struct ttm_operation_ctx ctx = { };
        int ret;

        do {
                ret = ttm_device_swapout(bdev, &ctx, GFP_KERNEL);
        } while (ret > 0);
        return ret;
}
EXPORT_SYMBOL(ttm_device_prepare_hibernation);

/*
 * A buffer object shrink method that tries to swap out the first
 * buffer object on the global::swap_lru list.
 */
int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags)
{
        struct ttm_global *glob = &ttm_glob;
        struct ttm_device *bdev;
        int ret = 0;

        mutex_lock(&ttm_global_mutex);
        list_for_each_entry(bdev, &glob->device_list, device_list) {
                ret = ttm_device_swapout(bdev, ctx, gfp_flags);
                if (ret > 0) {
                        list_move_tail(&bdev->device_list, &glob->device_list);
                        break;
                }
        }
        mutex_unlock(&ttm_global_mutex);
        return ret;
}

int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
                       gfp_t gfp_flags)
{
        struct ttm_resource_manager *man;
        unsigned i;
        s64 lret;

        for (i = TTM_PL_SYSTEM; i < TTM_NUM_MEM_TYPES; ++i) {
                man = ttm_manager_type(bdev, i);
                if (!man || !man->use_tt)
                        continue;

                lret = ttm_bo_swapout(bdev, ctx, man, gfp_flags, 1);
                /* Can be both positive (num_pages) and negative (error) */
                if (lret)
                        return lret;
        }
        return 0;
}
EXPORT_SYMBOL(ttm_device_swapout);

/**
 * ttm_device_init
 *
 * @bdev: A pointer to a struct ttm_device to initialize.
 * @funcs: Function table for the device.
 * @dev: The core kernel device pointer for DMA mappings and allocations.
 * @mapping: The address space to use for this bo.
 * @vma_manager: A pointer to a vma manager.
 * @alloc_flags: TTM_ALLOCATION_* flags.
 *
 * Initializes a struct ttm_device:
 * Returns:
 * !0: Failure.
 */
int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *funcs,
                    struct device *dev, struct address_space *mapping,
                    struct drm_vma_offset_manager *vma_manager,
                    unsigned int alloc_flags)
{
        struct ttm_global *glob = &ttm_glob;
        int ret, nid;

        if (WARN_ON(vma_manager == NULL))
                return -EINVAL;

        ret = ttm_global_init();
        if (ret)
                return ret;

        bdev->wq = alloc_workqueue("ttm",
                                   WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16);
        if (!bdev->wq) {
                ttm_global_release();
                return -ENOMEM;
        }

        bdev->alloc_flags = alloc_flags;
        bdev->funcs = funcs;

        ttm_sys_man_init(bdev);

        if (dev)
                nid = dev_to_node(dev);
        else
                nid = NUMA_NO_NODE;

        ttm_pool_init(&bdev->pool, dev, nid, alloc_flags);

        bdev->vma_manager = vma_manager;
        spin_lock_init(&bdev->lru_lock);
        INIT_LIST_HEAD(&bdev->unevictable);
        bdev->dev_mapping = mapping;
        mutex_lock(&ttm_global_mutex);
        list_add_tail(&bdev->device_list, &glob->device_list);
        mutex_unlock(&ttm_global_mutex);

        return 0;
}
EXPORT_SYMBOL(ttm_device_init);

void ttm_device_fini(struct ttm_device *bdev)
{
        struct ttm_resource_manager *man;
        unsigned i;

        mutex_lock(&ttm_global_mutex);
        list_del(&bdev->device_list);
        mutex_unlock(&ttm_global_mutex);

        drain_workqueue(bdev->wq);
        destroy_workqueue(bdev->wq);

        man = ttm_manager_type(bdev, TTM_PL_SYSTEM);
        ttm_resource_manager_set_used(man, false);
        ttm_set_driver_manager(bdev, TTM_PL_SYSTEM, NULL);

        spin_lock(&bdev->lru_lock);
        for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i)
                if (list_empty(&man->lru[0]))
                        pr_debug("Swap list %d was clean\n", i);
        spin_unlock(&bdev->lru_lock);

        ttm_pool_fini(&bdev->pool);
        ttm_global_release();
}
EXPORT_SYMBOL(ttm_device_fini);

static void ttm_device_clear_lru_dma_mappings(struct ttm_device *bdev,
                                              struct list_head *list)
{
        struct ttm_resource *res;

        spin_lock(&bdev->lru_lock);
        while ((res = ttm_lru_first_res_or_null(list))) {
                struct ttm_buffer_object *bo = res->bo;

                /* Take ref against racing releases once lru_lock is unlocked */
                if (!ttm_bo_get_unless_zero(bo))
                        continue;

                list_del_init(&bo->resource->lru.link);
                spin_unlock(&bdev->lru_lock);

                if (bo->ttm)
                        ttm_tt_unpopulate(bo->bdev, bo->ttm);

                ttm_bo_put(bo);
                spin_lock(&bdev->lru_lock);
        }
        spin_unlock(&bdev->lru_lock);
}

void ttm_device_clear_dma_mappings(struct ttm_device *bdev)
{
        struct ttm_resource_manager *man;
        unsigned int i, j;

        ttm_device_clear_lru_dma_mappings(bdev, &bdev->unevictable);

        for (i = TTM_PL_SYSTEM; i < TTM_NUM_MEM_TYPES; ++i) {
                man = ttm_manager_type(bdev, i);
                if (!man || !man->use_tt)
                        continue;

                for (j = 0; j < TTM_MAX_BO_PRIORITY; ++j)
                        ttm_device_clear_lru_dma_mappings(bdev, &man->lru[j]);
        }
}
EXPORT_SYMBOL(ttm_device_clear_dma_mappings);