[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>

1 files changed, 118 insertions, 2 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 494a824f57c4..a5804cf12c7c 100644
--- 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);