exynos_drm_dmabuf.c

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/* exynos_drm_dmabuf.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 * Author: Inki Dae <[email protected]>
 *
 * 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 (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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS 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.
 */

#include <drm/drmP.h>
#include <drm/exynos_drm.h>
#include "exynos_drm_drv.h"
#include "exynos_drm_gem.h"

#include <linux/dma-buf.h>

static struct sg_table *exynos_pages_to_sg(struct page **pages, int nr_pages,
        unsigned int page_size)
{
    struct sg_table *sgt = NULL;
    struct scatterlist *sgl;
    int i, ret;

    sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
    if (!sgt)
        goto out;

    ret = sg_alloc_table(sgt, nr_pages, GFP_KERNEL);
    if (ret)
        goto err_free_sgt;

    if (page_size < PAGE_SIZE)
        page_size = PAGE_SIZE;

    for_each_sg(sgt->sgl, sgl, nr_pages, i)
        sg_set_page(sgl, pages[i], page_size, 0);

    return sgt;

err_free_sgt:
    kfree(sgt);
    sgt = NULL;
out:
    return NULL;
}

static struct sg_table *
        exynos_gem_map_dma_buf(struct dma_buf_attachment *attach,
                    enum dma_data_direction dir)
{
    struct exynos_drm_gem_obj *gem_obj = attach->dmabuf->priv;
    struct drm_device *dev = gem_obj->base.dev;
    struct exynos_drm_gem_buf *buf;
    struct sg_table *sgt = NULL;
    unsigned int npages;
    int nents;

    DRM_DEBUG_PRIME("%s\n", __FILE__);

    mutex_lock(&dev->struct_mutex);

    buf = gem_obj->buffer;

    /* there should always be pages allocated. */
    if (!buf->pages) {
        DRM_ERROR("pages is null.\n");
        goto err_unlock;
    }

    npages = buf->size / buf->page_size;

    sgt = exynos_pages_to_sg(buf->pages, npages, buf->page_size);
    if (!sgt) {
        DRM_DEBUG_PRIME("exynos_pages_to_sg returned NULL!\n");
        goto err_unlock;
    }
    nents = dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);

    DRM_DEBUG_PRIME("npages = %d buffer size = 0x%lx page_size = 0x%lx\n",
            npages, buf->size, buf->page_size);

err_unlock:
    mutex_unlock(&dev->struct_mutex);
    return sgt;
}

static void exynos_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
                        struct sg_table *sgt,
                        enum dma_data_direction dir)
{
    dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
    sg_free_table(sgt);
    kfree(sgt);
    sgt = NULL;
}

static void exynos_dmabuf_release(struct dma_buf *dmabuf)
{
    struct exynos_drm_gem_obj *exynos_gem_obj = dmabuf->priv;

    DRM_DEBUG_PRIME("%s\n", __FILE__);

    /*
     * exynos_dmabuf_release() call means that file object's
     * f_count is 0 and it calls drm_gem_object_handle_unreference()
     * to drop the references that these values had been increased
     * at drm_prime_handle_to_fd()
     */
    if (exynos_gem_obj->base.export_dma_buf == dmabuf) {
        exynos_gem_obj->base.export_dma_buf = NULL;

        /*
         * drop this gem object refcount to release allocated buffer
         * and resources.
         */
        drm_gem_object_unreference_unlocked(&exynos_gem_obj->base);
    }
}

static void *exynos_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
                        unsigned long page_num)
{
    /* TODO */

    return NULL;
}

static void exynos_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
                        unsigned long page_num,
                        void *addr)
{
    /* TODO */
}

static void *exynos_gem_dmabuf_kmap(struct dma_buf *dma_buf,
                    unsigned long page_num)
{
    /* TODO */

    return NULL;
}

static void exynos_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
                    unsigned long page_num, void *addr)
{
    /* TODO */
}

static int exynos_gem_dmabuf_mmap(struct dma_buf *dma_buf,
    struct vm_area_struct *vma)
{
    return -ENOTTY;
}

static struct dma_buf_ops exynos_dmabuf_ops = {
    .map_dma_buf        = exynos_gem_map_dma_buf,
    .unmap_dma_buf      = exynos_gem_unmap_dma_buf,
    .kmap           = exynos_gem_dmabuf_kmap,
    .kmap_atomic        = exynos_gem_dmabuf_kmap_atomic,
    .kunmap         = exynos_gem_dmabuf_kunmap,
    .kunmap_atomic      = exynos_gem_dmabuf_kunmap_atomic,
    .mmap           = exynos_gem_dmabuf_mmap,
    .release        = exynos_dmabuf_release,
};

struct dma_buf *exynos_dmabuf_prime_export(struct drm_device *drm_dev,
                struct drm_gem_object *obj, int flags)
{
    struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);

    return dma_buf_export(exynos_gem_obj, &exynos_dmabuf_ops,
                exynos_gem_obj->base.size, 0600);
}

struct drm_gem_object *exynos_dmabuf_prime_import(struct drm_device *drm_dev,
                struct dma_buf *dma_buf)
{
    struct dma_buf_attachment *attach;
    struct sg_table *sgt;
    struct scatterlist *sgl;
    struct exynos_drm_gem_obj *exynos_gem_obj;
    struct exynos_drm_gem_buf *buffer;
    struct page *page;
    int ret;

    DRM_DEBUG_PRIME("%s\n", __FILE__);

    /* is this one of own objects? */
    if (dma_buf->ops == &exynos_dmabuf_ops) {
        struct drm_gem_object *obj;

        exynos_gem_obj = dma_buf->priv;
        obj = &exynos_gem_obj->base;

        /* is it from our device? */
        if (obj->dev == drm_dev) {
            drm_gem_object_reference(obj);
            return obj;
        }
    }

    attach = dma_buf_attach(dma_buf, drm_dev->dev);
    if (IS_ERR(attach))
        return ERR_PTR(-EINVAL);


    sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
    if (IS_ERR_OR_NULL(sgt)) {
        ret = PTR_ERR(sgt);
        goto err_buf_detach;
    }

    buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
    if (!buffer) {
        DRM_ERROR("failed to allocate exynos_drm_gem_buf.\n");
        ret = -ENOMEM;
        goto err_unmap_attach;
    }

    buffer->pages = kzalloc(sizeof(*page) * sgt->nents, GFP_KERNEL);
    if (!buffer->pages) {
        DRM_ERROR("failed to allocate pages.\n");
        ret = -ENOMEM;
        goto err_free_buffer;
    }

    exynos_gem_obj = exynos_drm_gem_init(drm_dev, dma_buf->size);
    if (!exynos_gem_obj) {
        ret = -ENOMEM;
        goto err_free_pages;
    }

    sgl = sgt->sgl;

    if (sgt->nents == 1) {
        buffer->dma_addr = sg_dma_address(sgt->sgl);
        buffer->size = sg_dma_len(sgt->sgl);

        /* always physically continuous memory if sgt->nents is 1. */
        exynos_gem_obj->flags |= EXYNOS_BO_CONTIG;
    } else {
        unsigned int i = 0;

        buffer->dma_addr = sg_dma_address(sgl);
        while (i < sgt->nents) {
            buffer->pages[i] = sg_page(sgl);
            buffer->size += sg_dma_len(sgl);
            sgl = sg_next(sgl);
            i++;
        }

        exynos_gem_obj->flags |= EXYNOS_BO_NONCONTIG;
    }

    exynos_gem_obj->buffer = buffer;
    buffer->sgt = sgt;
    exynos_gem_obj->base.import_attach = attach;

    DRM_DEBUG_PRIME("dma_addr = 0x%x, size = 0x%lx\n", buffer->dma_addr,
                                buffer->size);

    return &exynos_gem_obj->base;

err_free_pages:
    kfree(buffer->pages);
    buffer->pages = NULL;
err_free_buffer:
    kfree(buffer);
    buffer = NULL;
err_unmap_attach:
    dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
err_buf_detach:
    dma_buf_detach(dma_buf, attach);
    return ERR_PTR(ret);
}

MODULE_AUTHOR("Inki Dae <[email protected]>");
MODULE_DESCRIPTION("Samsung SoC DRM DMABUF Module");
MODULE_LICENSE("GPL");