[media] vb2-dma-sg: add support for dmabuf exports

Add DMABUF export support to vb2-dma-sg.

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
index 81e88a067882a24117c01626b52f5d96f7d2db3c..0566e94a5a1d1b2666971be23330011fb5f8c70a 100644 (file)
--- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
@@ -407,6 +407,175 @@ static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
        return 0;
 }
 
+/*********************************************/
+/*         DMABUF ops for exporters          */
+/*********************************************/
+
+struct vb2_dma_sg_attachment {
+       struct sg_table sgt;
+       enum dma_data_direction dma_dir;
+};
+
+static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
+       struct dma_buf_attachment *dbuf_attach)
+{
+       struct vb2_dma_sg_attachment *attach;
+       unsigned int i;
+       struct scatterlist *rd, *wr;
+       struct sg_table *sgt;
+       struct vb2_dma_sg_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->dma_sgt->orig_nents, GFP_KERNEL);
+       if (ret) {
+               kfree(attach);
+               return -ENOMEM;
+       }
+
+       rd = buf->dma_sgt->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->dma_dir = DMA_NONE;
+       dbuf_attach->priv = attach;
+
+       return 0;
+}
+
+static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
+       struct dma_buf_attachment *db_attach)
+{
+       struct vb2_dma_sg_attachment *attach = db_attach->priv;
+       struct sg_table *sgt;
+
+       if (!attach)
+               return;
+
+       sgt = &attach->sgt;
+
+       /* release the scatterlist cache */
+       if (attach->dma_dir != DMA_NONE)
+               dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
+                       attach->dma_dir);
+       sg_free_table(sgt);
+       kfree(attach);
+       db_attach->priv = NULL;
+}
+
+static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
+       struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
+{
+       struct vb2_dma_sg_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->dma_dir == dma_dir) {
+               mutex_unlock(lock);
+               return sgt;
+       }
+
+       /* release any previous cache */
+       if (attach->dma_dir != DMA_NONE) {
+               dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
+                       attach->dma_dir);
+               attach->dma_dir = DMA_NONE;
+       }
+
+       /* mapping to the client with new direction */
+       ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dma_dir);
+       if (ret <= 0) {
+               pr_err("failed to map scatterlist\n");
+               mutex_unlock(lock);
+               return ERR_PTR(-EIO);
+       }
+
+       attach->dma_dir = dma_dir;
+
+       mutex_unlock(lock);
+
+       return sgt;
+}
+
+static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
+       struct sg_table *sgt, enum dma_data_direction dma_dir)
+{
+       /* nothing to be done here */
+}
+
+static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
+{
+       /* drop reference obtained in vb2_dma_sg_get_dmabuf */
+       vb2_dma_sg_put(dbuf->priv);
+}
+
+static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
+{
+       struct vb2_dma_sg_buf *buf = dbuf->priv;
+
+       return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
+}
+
+static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
+{
+       struct vb2_dma_sg_buf *buf = dbuf->priv;
+
+       return vb2_dma_sg_vaddr(buf);
+}
+
+static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
+       struct vm_area_struct *vma)
+{
+       return vb2_dma_sg_mmap(dbuf->priv, vma);
+}
+
+static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
+       .attach = vb2_dma_sg_dmabuf_ops_attach,
+       .detach = vb2_dma_sg_dmabuf_ops_detach,
+       .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
+       .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
+       .kmap = vb2_dma_sg_dmabuf_ops_kmap,
+       .kmap_atomic = vb2_dma_sg_dmabuf_ops_kmap,
+       .vmap = vb2_dma_sg_dmabuf_ops_vmap,
+       .mmap = vb2_dma_sg_dmabuf_ops_mmap,
+       .release = vb2_dma_sg_dmabuf_ops_release,
+};
+
+static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
+{
+       struct vb2_dma_sg_buf *buf = buf_priv;
+       struct dma_buf *dbuf;
+
+       if (WARN_ON(!buf->dma_sgt))
+               return NULL;
+
+       dbuf = dma_buf_export(buf, &vb2_dma_sg_dmabuf_ops, buf->size, flags, NULL);
+       if (IS_ERR(dbuf))
+               return NULL;
+
+       /* dmabuf keeps reference to vb2 buffer */
+       atomic_inc(&buf->refcount);
+
+       return dbuf;
+}
+
 /*********************************************/
 /*       callbacks for DMABUF buffers        */
 /*********************************************/
@@ -523,6 +692,7 @@ const struct vb2_mem_ops vb2_dma_sg_memops = {
        .vaddr          = vb2_dma_sg_vaddr,
        .mmap           = vb2_dma_sg_mmap,
        .num_users      = vb2_dma_sg_num_users,
+       .get_dmabuf     = vb2_dma_sg_get_dmabuf,
        .map_dmabuf     = vb2_dma_sg_map_dmabuf,
        .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
        .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,