[media] v4l: vb2-dma-contig: add support for dma_buf importing

This patch makes changes for adding dma-contig as a dma_buf user. It provides
function implementations for the {attach, detach, map, unmap}_dmabuf()
mem_ops of DMABUF memory type.
	[author of the original patch]
	[integration with refactored dma-contig allocator]

Signed-off-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index 2e787cc..e30583b 100644 (file)
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -69,6 +69,7 @@ config VIDEOBUF2_DMA_CONTIG
        tristate
        select VIDEOBUF2_CORE
        select VIDEOBUF2_MEMOPS
+       select DMA_SHARED_BUFFER
 
 config VIDEOBUF2_VMALLOC
        tristate

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 494a824..a5804cf 100644 (file)
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -10,6 +10,7 @@
  * the Free Software Foundation.
  */
 
+#include <linux/dma-buf.h>
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 #include <linux/sched.h>
@@ -38,6 +39,9 @@ struct vb2_dc_buf {
 
        /* USERPTR related */
        struct vm_area_struct           *vma;
+
+       /* DMABUF related */
+       struct dma_buf_attachment       *db_attach;
 };
 
 /*********************************************/
@@ -108,7 +112,8 @@ static void vb2_dc_prepare(void *buf_priv)
        struct vb2_dc_buf *buf = buf_priv;
        struct sg_table *sgt = buf->dma_sgt;
 
-       if (!sgt)
+       /* DMABUF exporter will flush the cache for us */
+       if (!sgt || buf->db_attach)
                return;
 
        dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
@@ -119,7 +124,8 @@ static void vb2_dc_finish(void *buf_priv)
        struct vb2_dc_buf *buf = buf_priv;
        struct sg_table *sgt = buf->dma_sgt;
 
-       if (!sgt)
+       /* DMABUF exporter will flush the cache for us */
+       if (!sgt || buf->db_attach)
                return;
 
        dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
@@ -377,6 +383,112 @@ fail_buf:
 }
 
 /*********************************************/
+/*       callbacks for DMABUF buffers        */
+/*********************************************/
+
+static int vb2_dc_map_dmabuf(void *mem_priv)
+{
+       struct vb2_dc_buf *buf = mem_priv;
+       struct sg_table *sgt;
+       unsigned long contig_size;
+
+       if (WARN_ON(!buf->db_attach)) {
+               pr_err("trying to pin a non attached buffer\n");
+               return -EINVAL;
+       }
+
+       if (WARN_ON(buf->dma_sgt)) {
+               pr_err("dmabuf buffer is already pinned\n");
+               return 0;
+       }
+
+       /* get the associated scatterlist for this buffer */
+       sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
+       if (IS_ERR_OR_NULL(sgt)) {
+               pr_err("Error getting dmabuf scatterlist\n");
+               return -EINVAL;
+       }
+
+       /* checking if dmabuf is big enough to store contiguous chunk */
+       contig_size = vb2_dc_get_contiguous_size(sgt);
+       if (contig_size < buf->size) {
+               pr_err("contiguous chunk is too small %lu/%lu b\n",
+                       contig_size, buf->size);
+               dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
+               return -EFAULT;
+       }
+
+       buf->dma_addr = sg_dma_address(sgt->sgl);
+       buf->dma_sgt = sgt;
+
+       return 0;
+}
+
+static void vb2_dc_unmap_dmabuf(void *mem_priv)
+{
+       struct vb2_dc_buf *buf = mem_priv;
+       struct sg_table *sgt = buf->dma_sgt;
+
+       if (WARN_ON(!buf->db_attach)) {
+               pr_err("trying to unpin a not attached buffer\n");
+               return;
+       }
+
+       if (WARN_ON(!sgt)) {
+               pr_err("dmabuf buffer is already unpinned\n");
+               return;
+       }
+
+       dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
+
+       buf->dma_addr = 0;
+       buf->dma_sgt = NULL;
+}
+
+static void vb2_dc_detach_dmabuf(void *mem_priv)
+{
+       struct vb2_dc_buf *buf = mem_priv;
+
+       /* if vb2 works correctly you should never detach mapped buffer */
+       if (WARN_ON(buf->dma_addr))
+               vb2_dc_unmap_dmabuf(buf);
+
+       /* detach this attachment */
+       dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
+       kfree(buf);
+}
+
+static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
+       unsigned long size, int write)
+{
+       struct vb2_dc_conf *conf = alloc_ctx;
+       struct vb2_dc_buf *buf;
+       struct dma_buf_attachment *dba;
+
+       if (dbuf->size < size)
+               return ERR_PTR(-EFAULT);
+
+       buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+       if (!buf)
+               return ERR_PTR(-ENOMEM);
+
+       buf->dev = conf->dev;
+       /* create attachment for the dmabuf with the user device */
+       dba = dma_buf_attach(dbuf, buf->dev);
+       if (IS_ERR(dba)) {
+               pr_err("failed to attach dmabuf\n");
+               kfree(buf);
+               return dba;
+       }
+
+       buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+       buf->size = size;
+       buf->db_attach = dba;
+
+       return buf;
+}
+
+/*********************************************/
 /*       DMA CONTIG exported functions       */
 /*********************************************/
 
@@ -390,6 +502,10 @@ const struct vb2_mem_ops vb2_dma_contig_memops = {
        .put_userptr    = vb2_dc_put_userptr,
        .prepare        = vb2_dc_prepare,
        .finish         = vb2_dc_finish,
+       .map_dmabuf     = vb2_dc_map_dmabuf,
+       .unmap_dmabuf   = vb2_dc_unmap_dmabuf,
+       .attach_dmabuf  = vb2_dc_attach_dmabuf,
+       .detach_dmabuf  = vb2_dc_detach_dmabuf,
        .num_users      = vb2_dc_num_users,
 };
 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);