Hi Tomasz,
On Wednesday 10 October 2012 16:46:39 Tomasz Stanislawski wrote:
> This patch adds support for exporting a dma-contig buffer using
> DMABUF interface.
>
> Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-dma-contig.c | 200 +++++++++++++++++++++
> 1 file changed, 200 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c
> b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 0e065ce..b138b5c
> 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> @@ -36,6 +36,7 @@ struct vb2_dc_buf {
> /* MMAP related */
> struct vb2_vmarea_handler handler;
> atomic_t refcount;
> + struct sg_table *sgt_base;
>
> /* USERPTR related */
> struct vm_area_struct *vma;
> @@ -142,6 +143,10 @@ static void vb2_dc_put(void *buf_priv)
> if (!atomic_dec_and_test(&buf->refcount))
> return;
>
> + if (buf->sgt_base) {
> + sg_free_table(buf->sgt_base);
> + kfree(buf->sgt_base);
> + }
> dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
> kfree(buf);
> }
> @@ -213,6 +218,200 @@ static int vb2_dc_mmap(void *buf_priv, struct
> vm_area_struct *vma) }
>
> /*********************************************/
> +/* DMABUF ops for exporters */
> +/*********************************************/
> +
> +struct vb2_dc_attachment {
> + struct sg_table sgt;
> + enum dma_data_direction dir;
> +};
> +
> +static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device
> *dev, + struct dma_buf_attachment *dbuf_attach)
> +{
> + struct vb2_dc_attachment *attach;
> + unsigned int i;
> + struct scatterlist *rd, *wr;
> + struct sg_table *sgt;
> + struct vb2_dc_buf *buf = dbuf->priv;
> + int ret;
> +
> + attach = kzalloc(sizeof(*attach), GFP_KERNEL);
> + if (!attach)
> + return -ENOMEM;
> +
> + sgt = &attach->sgt;
> + /* Copy the buf->base_sgt scatter list to the attachment, as we can't
> + * map the same scatter list to multiple attachments at the same time.
> + */
> + ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
> + if (ret) {
> + kfree(attach);
> + return -ENOMEM;
> + }
> +
> + rd = buf->sgt_base->sgl;
> + wr = sgt->sgl;
> + for (i = 0; i < sgt->orig_nents; ++i) {
> + sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
> + rd = sg_next(rd);
> + wr = sg_next(wr);
> + }
> +
> + attach->dir = DMA_NONE;
> + dbuf_attach->priv = attach;
> +
> + return 0;
> +}
> +
> +static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
> + struct dma_buf_attachment *db_attach)
> +{
> + struct vb2_dc_attachment *attach = db_attach->priv;
> + struct sg_table *sgt;
> +
> + if (!attach)
> + return;
> +
> + sgt = &attach->sgt;
> +
> + /* release the scatterlist cache */
> + if (attach->dir != DMA_NONE)
> + dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
> + attach->dir);
> + sg_free_table(sgt);
> + kfree(attach);
> + db_attach->priv = NULL;
> +}
> +
> +static struct sg_table *vb2_dc_dmabuf_ops_map(
> + struct dma_buf_attachment *db_attach, enum dma_data_direction dir)
> +{
> + struct vb2_dc_attachment *attach = db_attach->priv;
> + /* stealing dmabuf mutex to serialize map/unmap operations */
> + struct mutex *lock = &db_attach->dmabuf->lock;
> + struct sg_table *sgt;
> + int ret;
> +
> + mutex_lock(lock);
> +
> + sgt = &attach->sgt;
> + /* return previously mapped sg table */
> + if (attach->dir == dir) {
> + mutex_unlock(lock);
> + return sgt;
> + }
> +
> + /* release any previous cache */
> + if (attach->dir != DMA_NONE) {
> + dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
> + attach->dir);
> + attach->dir = DMA_NONE;
> + }
> +
> + /* mapping to the client with new direction */
> + ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dir);
> + if (ret <= 0) {
> + pr_err("failed to map scatterlist\n");
> + mutex_unlock(lock);
> + return ERR_PTR(-EIO);
> + }
> +
> + attach->dir = dir;
> +
> + mutex_unlock(lock);
> +
> + return sgt;
> +}
> +
> +static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
> + struct sg_table *sgt, enum dma_data_direction dir)
> +{
> + /* nothing to be done here */
> +}
> +
> +static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
> +{
> + /* drop reference obtained in vb2_dc_get_dmabuf */
> + vb2_dc_put(dbuf->priv);
> +}
> +
> +static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long
> pgnum) +{
> + struct vb2_dc_buf *buf = dbuf->priv;
> +
> + return buf->vaddr + pgnum * PAGE_SIZE;
> +}
> +
> +static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
> +{
> + struct vb2_dc_buf *buf = dbuf->priv;
> +
> + return buf->vaddr;
> +}
> +
> +static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
> + struct vm_area_struct *vma)
> +{
> + return vb2_dc_mmap(dbuf->priv, vma);
> +}
> +
> +static struct dma_buf_ops vb2_dc_dmabuf_ops = {
> + .attach = vb2_dc_dmabuf_ops_attach,
> + .detach = vb2_dc_dmabuf_ops_detach,
> + .map_dma_buf = vb2_dc_dmabuf_ops_map,
> + .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
> + .kmap = vb2_dc_dmabuf_ops_kmap,
> + .kmap_atomic = vb2_dc_dmabuf_ops_kmap,
> + .vmap = vb2_dc_dmabuf_ops_vmap,
> + .mmap = vb2_dc_dmabuf_ops_mmap,
> + .release = vb2_dc_dmabuf_ops_release,
> +};
> +
> +static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
> +{
> + int ret;
> + struct sg_table *sgt;
> +
> + sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
> + if (!sgt) {
> + dev_err(buf->dev, "failed to alloc sg table\n");
> + return NULL;
> + }
> +
> + ret = dma_get_sgtable(buf->dev, sgt, buf->vaddr, buf->dma_addr,
> + buf->size);
> + if (ret < 0) {
> + dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
> + kfree(sgt);
> + return NULL;
> + }
> +
> + return sgt;
> +}
> +
> +static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv)
> +{
> + struct vb2_dc_buf *buf = buf_priv;
> + struct dma_buf *dbuf;
> +
> + if (!buf->sgt_base)
> + buf->sgt_base = vb2_dc_get_base_sgt(buf);
> +
> + if (WARN_ON(!buf->sgt_base))
> + return NULL;
> +
> + dbuf = dma_buf_export(buf, &vb2_dc_dmabuf_ops, buf->size, 0);
> + if (IS_ERR(dbuf))
> + return NULL;
> +
> + /* dmabuf keeps reference to vb2 buffer */
> + atomic_inc(&buf->refcount);
> +
> + return dbuf;
> +}
> +
> +/*********************************************/
> /* callbacks for USERPTR buffers */
> /*********************************************/
>
> @@ -519,6 +718,7 @@ static void *vb2_dc_attach_dmabuf(void *alloc_ctx,
> struct dma_buf *dbuf, const struct vb2_mem_ops vb2_dma_contig_memops = {
> .alloc = vb2_dc_alloc,
> .put = vb2_dc_put,
> + .get_dmabuf = vb2_dc_get_dmabuf,
> .cookie = vb2_dc_cookie,
> .vaddr = vb2_dc_vaddr,
> .mmap = vb2_dc_mmap,
--
Regards,
Laurent Pinchart
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