/**************************************************************************
 *
 * 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>
 */

#include <linux/sched.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/shmem_fs.h>
#include <linux/file.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/export.h>
#include "drm_cache.h"
#include "drm_mem_util.h"
#include "ttm/ttm_module.h"
#include "ttm/ttm_bo_driver.h"
#include "ttm/ttm_placement.h"
#include "ttm/ttm_page_alloc.h"

static int ttm_tt_swapin(struct ttm_tt *ttm);

/**
 * Allocates storage for pointers to the pages that back the ttm.
 */
static void ttm_tt_alloc_page_directory(struct ttm_tt *ttm)
{
        ttm->pages = drm_calloc_large(ttm->num_pages, sizeof(*ttm->pages));
        ttm->dma_address = drm_calloc_large(ttm->num_pages,
                                            sizeof(*ttm->dma_address));
}

static void ttm_tt_free_page_directory(struct ttm_tt *ttm)
{
        drm_free_large(ttm->pages);
        ttm->pages = NULL;
        drm_free_large(ttm->dma_address);
        ttm->dma_address = NULL;
}

static void ttm_tt_free_user_pages(struct ttm_tt *ttm)
{
        int write;
        int dirty;
        struct page *page;
        int i;
        struct ttm_backend *be = ttm->be;

        BUG_ON(!(ttm->page_flags & TTM_PAGE_FLAG_USER));
        write = ((ttm->page_flags & TTM_PAGE_FLAG_WRITE) != 0);
        dirty = ((ttm->page_flags & TTM_PAGE_FLAG_USER_DIRTY) != 0);

        if (be)
                be->func->clear(be);

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

                if (page == ttm->dummy_read_page) {
                        BUG_ON(write);
                        continue;
                }

                if (write && dirty && !PageReserved(page))
                        set_page_dirty_lock(page);

                ttm->pages[i] = NULL;
                ttm_mem_global_free(ttm->glob->mem_glob, PAGE_SIZE);
                put_page(page);
        }
        ttm->state = tt_unpopulated;
        ttm->first_himem_page = ttm->num_pages;
        ttm->last_lomem_page = -1;
}

static struct page *__ttm_tt_get_page(struct ttm_tt *ttm, int index)
{
        struct page *p;
        struct list_head h;
        struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
        int ret;

        while (NULL == (p = ttm->pages[index])) {

                INIT_LIST_HEAD(&h);

                ret = ttm_get_pages(&h, ttm->page_flags, ttm->caching_state, 1,
                                    &ttm->dma_address[index]);

                if (ret != 0)
                        return NULL;

                p = list_first_entry(&h, struct page, lru);

                ret = ttm_mem_global_alloc_page(mem_glob, p, false, false);
                if (unlikely(ret != 0))
                        goto out_err;

                if (PageHighMem(p))
                        ttm->pages[--ttm->first_himem_page] = p;
                else
                        ttm->pages[++ttm->last_lomem_page] = p;
        }
        return p;
out_err:
        put_page(p);
        return NULL;
}

struct page *ttm_tt_get_page(struct ttm_tt *ttm, int index)
{
        int ret;

        if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
                ret = ttm_tt_swapin(ttm);
                if (unlikely(ret != 0))
                        return NULL;
        }
        return __ttm_tt_get_page(ttm, index);
}

int ttm_tt_populate(struct ttm_tt *ttm)
{
        struct page *page;
        unsigned long i;
        struct ttm_backend *be;
        int ret;

        if (ttm->state != tt_unpopulated)
                return 0;

        if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
                ret = ttm_tt_swapin(ttm);
                if (unlikely(ret != 0))
                        return ret;
        }

        be = ttm->be;

        for (i = 0; i < ttm->num_pages; ++i) {
                page = __ttm_tt_get_page(ttm, i);
                if (!page)
                        return -ENOMEM;
        }

        be->func->populate(be, ttm->num_pages, ttm->pages,
                           ttm->dummy_read_page, ttm->dma_address);
        ttm->state = tt_unbound;
        return 0;
}
EXPORT_SYMBOL(ttm_tt_populate);

#ifdef CONFIG_X86
static inline int ttm_tt_set_page_caching(struct page *p,
                                          enum ttm_caching_state c_old,
                                          enum ttm_caching_state c_new)
{
        int ret = 0;

        if (PageHighMem(p))
                return 0;

        if (c_old != tt_cached) {
                /* p isn't in the default caching state, set it to
                 * writeback first to free its current memtype. */

                ret = set_pages_wb(p, 1);
                if (ret)
                        return ret;
        }

        if (c_new == tt_wc)
                ret = set_memory_wc((unsigned long) page_address(p), 1);
        else if (c_new == tt_uncached)
                ret = set_pages_uc(p, 1);

        return ret;
}
#else /* CONFIG_X86 */
static inline int ttm_tt_set_page_caching(struct page *p,
                                          enum ttm_caching_state c_old,
                                          enum ttm_caching_state c_new)
{
        return 0;
}
#endif /* CONFIG_X86 */

/*
 * Change caching policy for the linear kernel map
 * for range of pages in a ttm.
 */

static int ttm_tt_set_caching(struct ttm_tt *ttm,
                              enum ttm_caching_state c_state)
{
        int i, j;
        struct page *cur_page;
        int ret;

        if (ttm->caching_state == c_state)
                return 0;

        if (ttm->state == tt_unpopulated) {
                /* Change caching but don't populate */
                ttm->caching_state = c_state;
                return 0;
        }

        if (ttm->caching_state == tt_cached)
                drm_clflush_pages(ttm->pages, ttm->num_pages);

        for (i = 0; i < ttm->num_pages; ++i) {
                cur_page = ttm->pages[i];
                if (likely(cur_page != NULL)) {
                        ret = ttm_tt_set_page_caching(cur_page,
                                                      ttm->caching_state,
                                                      c_state);
                        if (unlikely(ret != 0))
                                goto out_err;
                }
        }

        ttm->caching_state = c_state;

        return 0;

out_err:
        for (j = 0; j < i; ++j) {
                cur_page = ttm->pages[j];
                if (likely(cur_page != NULL)) {
                        (void)ttm_tt_set_page_caching(cur_page, c_state,
                                                      ttm->caching_state);
                }
        }

        return ret;
}

int ttm_tt_set_placement_caching(struct ttm_tt *ttm, uint32_t placement)
{
        enum ttm_caching_state state;

        if (placement & TTM_PL_FLAG_WC)
                state = tt_wc;
        else if (placement & TTM_PL_FLAG_UNCACHED)
                state = tt_uncached;
        else
                state = tt_cached;

        return ttm_tt_set_caching(ttm, state);
}
EXPORT_SYMBOL(ttm_tt_set_placement_caching);

static void ttm_tt_free_alloced_pages(struct ttm_tt *ttm)
{
        int i;
        unsigned count = 0;
        struct list_head h;
        struct page *cur_page;
        struct ttm_backend *be = ttm->be;

        INIT_LIST_HEAD(&h);

        if (be)
                be->func->clear(be);
        for (i = 0; i < ttm->num_pages; ++i) {

                cur_page = ttm->pages[i];
                ttm->pages[i] = NULL;
                if (cur_page) {
                        if (page_count(cur_page) != 1)
                                printk(KERN_ERR TTM_PFX
                                       "Erroneous page count. "
                                       "Leaking pages.\n");
                        ttm_mem_global_free_page(ttm->glob->mem_glob,
                                                 cur_page);
                        list_add(&cur_page->lru, &h);
                        count++;
                }
        }
        ttm_put_pages(&h, count, ttm->page_flags, ttm->caching_state,
                      ttm->dma_address);
        ttm->state = tt_unpopulated;
        ttm->first_himem_page = ttm->num_pages;
        ttm->last_lomem_page = -1;
}

void ttm_tt_destroy(struct ttm_tt *ttm)
{
        struct ttm_backend *be;

        if (unlikely(ttm == NULL))
                return;

        be = ttm->be;
        if (likely(be != NULL)) {
                be->func->destroy(be);
                ttm->be = NULL;
        }

        if (likely(ttm->pages != NULL)) {
                if (ttm->page_flags & TTM_PAGE_FLAG_USER)
                        ttm_tt_free_user_pages(ttm);
                else
                        ttm_tt_free_alloced_pages(ttm);

                ttm_tt_free_page_directory(ttm);
        }

        if (!(ttm->page_flags & TTM_PAGE_FLAG_PERSISTENT_SWAP) &&
            ttm->swap_storage)
                fput(ttm->swap_storage);

        kfree(ttm);
}

int ttm_tt_set_user(struct ttm_tt *ttm,
                    struct task_struct *tsk,
                    unsigned long start, unsigned long num_pages)
{
        struct mm_struct *mm = tsk->mm;
        int ret;
        int write = (ttm->page_flags & TTM_PAGE_FLAG_WRITE) != 0;
        struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;

        BUG_ON(num_pages != ttm->num_pages);
        BUG_ON((ttm->page_flags & TTM_PAGE_FLAG_USER) == 0);

        /**
         * Account user pages as lowmem pages for now.
         */

        ret = ttm_mem_global_alloc(mem_glob, num_pages * PAGE_SIZE,
                                   false, false);
        if (unlikely(ret != 0))
                return ret;

        down_read(&mm->mmap_sem);
        ret = get_user_pages(tsk, mm, start, num_pages,
                             write, 0, ttm->pages, NULL);
        up_read(&mm->mmap_sem);

        if (ret != num_pages && write) {
                ttm_tt_free_user_pages(ttm);
                ttm_mem_global_free(mem_glob, num_pages * PAGE_SIZE);
                return -ENOMEM;
        }

        ttm->tsk = tsk;
        ttm->start = start;
        ttm->state = tt_unbound;

        return 0;
}

struct ttm_tt *ttm_tt_create(struct ttm_bo_device *bdev, unsigned long size,
                             uint32_t page_flags, struct page *dummy_read_page)
{
        struct ttm_bo_driver *bo_driver = bdev->driver;
        struct ttm_tt *ttm;

        if (!bo_driver)
                return NULL;

        ttm = kzalloc(sizeof(*ttm), GFP_KERNEL);
        if (!ttm)
                return NULL;

        ttm->glob = bdev->glob;
        ttm->num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
        ttm->first_himem_page = ttm->num_pages;
        ttm->last_lomem_page = -1;
        ttm->caching_state = tt_cached;
        ttm->page_flags = page_flags;

        ttm->dummy_read_page = dummy_read_page;

        ttm_tt_alloc_page_directory(ttm);
        if (!ttm->pages) {
                ttm_tt_destroy(ttm);
                printk(KERN_ERR TTM_PFX "Failed allocating page table\n");
                return NULL;
        }
        ttm->be = bo_driver->create_ttm_backend_entry(bdev);
        if (!ttm->be) {
                ttm_tt_destroy(ttm);
                printk(KERN_ERR TTM_PFX "Failed creating ttm backend entry\n");
                return NULL;
        }
        ttm->state = tt_unpopulated;
        return ttm;
}

void ttm_tt_unbind(struct ttm_tt *ttm)
{
        int ret;
        struct ttm_backend *be = ttm->be;

        if (ttm->state == tt_bound) {
                ret = be->func->unbind(be);
                BUG_ON(ret);
                ttm->state = tt_unbound;
        }
}

int ttm_tt_bind(struct ttm_tt *ttm, struct ttm_mem_reg *bo_mem)
{
        int ret = 0;
        struct ttm_backend *be;

        if (!ttm)
                return -EINVAL;

        if (ttm->state == tt_bound)
                return 0;

        be = ttm->be;

        ret = ttm_tt_populate(ttm);
        if (ret)
                return ret;

        ret = be->func->bind(be, bo_mem);
        if (unlikely(ret != 0))
                return ret;

        ttm->state = tt_bound;

        if (ttm->page_flags & TTM_PAGE_FLAG_USER)
                ttm->page_flags |= TTM_PAGE_FLAG_USER_DIRTY;
        return 0;
}
EXPORT_SYMBOL(ttm_tt_bind);

static 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;
        void *from_virtual;
        void *to_virtual;
        int i;
        int ret = -ENOMEM;

        if (ttm->page_flags & TTM_PAGE_FLAG_USER) {
                ret = ttm_tt_set_user(ttm, ttm->tsk, ttm->start,
                                      ttm->num_pages);
                if (unlikely(ret != 0))
                        return ret;

                ttm->page_flags &= ~TTM_PAGE_FLAG_SWAPPED;
                return 0;
        }

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

        swap_space = swap_storage->f_path.dentry->d_inode->i_mapping;

        for (i = 0; i < ttm->num_pages; ++i) {
                from_page = shmem_read_mapping_page(swap_space, i);
                if (IS_ERR(from_page)) {
                        ret = PTR_ERR(from_page);
                        goto out_err;
                }
                to_page = __ttm_tt_get_page(ttm, i);
                if (unlikely(to_page == NULL))
                        goto out_err;

                preempt_disable();
                from_virtual = kmap_atomic(from_page, KM_USER0);
                to_virtual = kmap_atomic(to_page, KM_USER1);
                memcpy(to_virtual, from_virtual, PAGE_SIZE);
                kunmap_atomic(to_virtual, KM_USER1);
                kunmap_atomic(from_virtual, KM_USER0);
                preempt_enable();
                page_cache_release(from_page);
        }

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

        return 0;
out_err:
        ttm_tt_free_alloced_pages(ttm);
        return ret;
}

int ttm_tt_swapout(struct ttm_tt *ttm, struct file *persistent_swap_storage)
{
        struct address_space *swap_space;
        struct file *swap_storage;
        struct page *from_page;
        struct page *to_page;
        void *from_virtual;
        void *to_virtual;
        int i;
        int ret = -ENOMEM;

        BUG_ON(ttm->state != tt_unbound && ttm->state != tt_unpopulated);
        BUG_ON(ttm->caching_state != tt_cached);

        /*
         * For user buffers, just unpin the pages, as there should be
         * vma references.
         */

        if (ttm->page_flags & TTM_PAGE_FLAG_USER) {
                ttm_tt_free_user_pages(ttm);
                ttm->page_flags |= TTM_PAGE_FLAG_SWAPPED;
                ttm->swap_storage = NULL;
                return 0;
        }

        if (!persistent_swap_storage) {
                swap_storage = shmem_file_setup("ttm swap",
                                                ttm->num_pages << PAGE_SHIFT,
                                                0);
                if (unlikely(IS_ERR(swap_storage))) {
                        printk(KERN_ERR "Failed allocating swap storage.\n");
                        return PTR_ERR(swap_storage);
                }
        } else
                swap_storage = persistent_swap_storage;

        swap_space = swap_storage->f_path.dentry->d_inode->i_mapping;

        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(swap_space, i);
                if (unlikely(IS_ERR(to_page))) {
                        ret = PTR_ERR(to_page);
                        goto out_err;
                }
                preempt_disable();
                from_virtual = kmap_atomic(from_page, KM_USER0);
                to_virtual = kmap_atomic(to_page, KM_USER1);
                memcpy(to_virtual, from_virtual, PAGE_SIZE);
                kunmap_atomic(to_virtual, KM_USER1);
                kunmap_atomic(from_virtual, KM_USER0);
                preempt_enable();
                set_page_dirty(to_page);
                mark_page_accessed(to_page);
                page_cache_release(to_page);
        }

        ttm_tt_free_alloced_pages(ttm);
        ttm->swap_storage = swap_storage;
        ttm->page_flags |= TTM_PAGE_FLAG_SWAPPED;
        if (persistent_swap_storage)
                ttm->page_flags |= TTM_PAGE_FLAG_PERSISTENT_SWAP;

        return 0;
out_err:
        if (!persistent_swap_storage)
                fput(swap_storage);

        return ret;
}