/*
 * drivers/staging/omapdrm/omap_gem_helpers.c
 *
 * Copyright (C) 2011 Texas Instruments
 * Author: Rob Clark <rob.clark@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/* temporary copy of drm_gem_{get,put}_pages() until the
 * "drm/gem: add functions to get/put pages" patch is merged..
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/shmem_fs.h>

#include <drm/drmP.h>

/**
 * drm_gem_get_pages - helper to allocate backing pages for a GEM object
 * @obj: obj in question
 * @gfpmask: gfp mask of requested pages
 */
struct page ** _drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask)
{
	struct inode *inode;
	struct address_space *mapping;
	struct page *p, **pages;
	int i, npages;

	/* This is the shared memory object that backs the GEM resource */
	inode = obj->filp->f_path.dentry->d_inode;
	mapping = inode->i_mapping;

	npages = obj->size >> PAGE_SHIFT;

	pages = drm_malloc_ab(npages, sizeof(struct page *));
	if (pages == NULL)
		return ERR_PTR(-ENOMEM);

	gfpmask |= mapping_gfp_mask(mapping);

	for (i = 0; i < npages; i++) {
		p = shmem_read_mapping_page_gfp(mapping, i, gfpmask);
		if (IS_ERR(p))
			goto fail;
		pages[i] = p;

		/* There is a hypothetical issue w/ drivers that require
		 * buffer memory in the low 4GB.. if the pages are un-
		 * pinned, and swapped out, they can end up swapped back
		 * in above 4GB.  If pages are already in memory, then
		 * shmem_read_mapping_page_gfp will ignore the gfpmask,
		 * even if the already in-memory page disobeys the mask.
		 *
		 * It is only a theoretical issue today, because none of
		 * the devices with this limitation can be populated with
		 * enough memory to trigger the issue.  But this BUG_ON()
		 * is here as a reminder in case the problem with
		 * shmem_read_mapping_page_gfp() isn't solved by the time
		 * it does become a real issue.
		 *
		 * See this thread: http://lkml.org/lkml/2011/7/11/238
		 */
		BUG_ON((gfpmask & __GFP_DMA32) &&
				(page_to_pfn(p) >= 0x00100000UL));
	}

	return pages;

fail:
	while (i--) {
		page_cache_release(pages[i]);
	}
	drm_free_large(pages);
	return ERR_CAST(p);
}

/**
 * drm_gem_put_pages - helper to free backing pages for a GEM object
 * @obj: obj in question
 * @pages: pages to free
 */
void _drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
		bool dirty, bool accessed)
{
	int i, npages;

	npages = obj->size >> PAGE_SHIFT;

	for (i = 0; i < npages; i++) {
		if (dirty)
			set_page_dirty(pages[i]);

		if (accessed)
			mark_page_accessed(pages[i]);

		/* Undo the reference we took when populating the table */
		page_cache_release(pages[i]);
	}

	drm_free_large(pages);
}

int
_drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
{
	struct drm_device *dev = obj->dev;
	struct drm_gem_mm *mm = dev->mm_private;
	struct drm_map_list *list;
	struct drm_local_map *map;
	int ret = 0;

	/* Set the object up for mmap'ing */
	list = &obj->map_list;
	list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
	if (!list->map)
		return -ENOMEM;

	map = list->map;
	map->type = _DRM_GEM;
	map->size = size;
	map->handle = obj;

	/* Get a DRM GEM mmap offset allocated... */
	list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
			size / PAGE_SIZE, 0, 0);

	if (!list->file_offset_node) {
		DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
		ret = -ENOSPC;
		goto out_free_list;
	}

	list->file_offset_node = drm_mm_get_block(list->file_offset_node,
			size / PAGE_SIZE, 0);
	if (!list->file_offset_node) {
		ret = -ENOMEM;
		goto out_free_list;
	}

	list->hash.key = list->file_offset_node->start;
	ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
	if (ret) {
		DRM_ERROR("failed to add to map hash\n");
		goto out_free_mm;
	}

	return 0;

out_free_mm:
	drm_mm_put_block(list->file_offset_node);
out_free_list:
	kfree(list->map);
	list->map = NULL;

	return ret;
}