[media] v4l: vb2: add buffer exporting via dmabuf

This patch adds extension to videobuf2-core. It allow to export an mmap buffer
as a DMABUF file descriptor.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 96 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index 017fed8ad2ab..438ea45d1074 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -369,6 +369,19 @@ int v4l2_m2m_dqbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 EXPORT_SYMBOL_GPL(v4l2_m2m_dqbuf);
 
 /**
+ * v4l2_m2m_expbuf() - export a source or destination buffer, depending on
+ * the type
+ */
+int v4l2_m2m_expbuf(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
+                  struct v4l2_exportbuffer *eb)
+{
+        struct vb2_queue *vq;
+
+        vq = v4l2_m2m_get_vq(m2m_ctx, eb->type);
+        return vb2_expbuf(vq, eb);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_expbuf);
+/**
  * v4l2_m2m_streamon() - turn on streaming for a video queue
  */
 int v4l2_m2m_streamon(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 613dea16a304..9f81be23a81f 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -1751,6 +1751,79 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off,
 }
 
 /**
+ * vb2_expbuf() - Export a buffer as a file descriptor
+ * @q:          videobuf2 queue
+ * @eb:         export buffer structure passed from userspace to vidioc_expbuf
+ *              handler in driver
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_expbuf handler in driver.
+ */
+int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb)
+{
+        struct vb2_buffer *vb = NULL;
+        struct vb2_plane *vb_plane;
+        int ret;
+        struct dma_buf *dbuf;
+
+        if (q->memory != V4L2_MEMORY_MMAP) {
+                dprintk(1, "Queue is not currently set up for mmap\n");
+                return -EINVAL;
+        }
+
+        if (!q->mem_ops->get_dmabuf) {
+                dprintk(1, "Queue does not support DMA buffer exporting\n");
+                return -EINVAL;
+        }
+
+        if (eb->flags & ~O_CLOEXEC) {
+                dprintk(1, "Queue does support only O_CLOEXEC flag\n");
+                return -EINVAL;
+        }
+
+        if (eb->type != q->type) {
+                dprintk(1, "qbuf: invalid buffer type\n");
+                return -EINVAL;
+        }
+
+        if (eb->index >= q->num_buffers) {
+                dprintk(1, "buffer index out of range\n");
+                return -EINVAL;
+        }
+
+        vb = q->bufs[eb->index];
+
+        if (eb->plane >= vb->num_planes) {
+                dprintk(1, "buffer plane out of range\n");
+                return -EINVAL;
+        }
+
+        vb_plane = &vb->planes[eb->plane];
+
+        dbuf = call_memop(q, get_dmabuf, vb_plane->mem_priv);
+        if (IS_ERR_OR_NULL(dbuf)) {
+                dprintk(1, "Failed to export buffer %d, plane %d\n",
+                        eb->index, eb->plane);
+                return -EINVAL;
+        }
+
+        ret = dma_buf_fd(dbuf, eb->flags);
+        if (ret < 0) {
+                dprintk(3, "buffer %d, plane %d failed to export (%d)\n",
+                        eb->index, eb->plane, ret);
+                dma_buf_put(dbuf);
+                return ret;
+        }
+
+        dprintk(3, "buffer %d, plane %d exported as %d descriptor\n",
+                eb->index, eb->plane, ret);
+        eb->fd = ret;
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(vb2_expbuf);
+
+/**
  * vb2_mmap() - map video buffers into application address space
  * @q:          videobuf2 queue
  * @vma:        vma passed to the mmap file operation handler in the driver
@@ -2456,6 +2529,16 @@ int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i)
 }
 EXPORT_SYMBOL_GPL(vb2_ioctl_streamoff);
 
+int vb2_ioctl_expbuf(struct file *file, void *priv, struct v4l2_exportbuffer *p)
+{
+        struct video_device *vdev = video_devdata(file);
+
+        if (vb2_queue_is_busy(vdev, file))
+                return -EBUSY;
+        return vb2_expbuf(vdev->queue, p);
+}
+EXPORT_SYMBOL_GPL(vb2_ioctl_expbuf);
+
 /* v4l2_file_operations helpers */
 
 int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)