omap_gem_helpers.c

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/*
 * drivers/staging/omapdrm/omap_gem_helpers.c
 *
 * Copyright (C) 2011 Texas Instruments
 * Author: Rob Clark <[email protected]>
 *
 * 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>

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);
}

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;
}