[media] v4l: add buffer exporting via dmabuf

This patch adds extension to V4L2 api. A new ioctl VIDIOC_EXPBUF is added.  The
ioctl is used 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: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 91ac83b21c20..3cf3e946e331 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -694,6 +694,33 @@ struct v4l2_buffer {
 #define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE       0x0800
 #define V4L2_BUF_FLAG_NO_CACHE_CLEAN            0x1000
 
+/**
+ * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
+ *
+ * @index:      id number of the buffer
+ * @type:       enum v4l2_buf_type; buffer type (type == *_MPLANE for
+ *              multiplanar buffers);
+ * @plane:      index of the plane to be exported, 0 for single plane queues
+ * @flags:      flags for newly created file, currently only O_CLOEXEC is
+ *              supported, refer to manual of open syscall for more details
+ * @fd:         file descriptor associated with DMABUF (set by driver)
+ *
+ * Contains data used for exporting a video buffer as DMABUF file descriptor.
+ * The buffer is identified by a 'cookie' returned by VIDIOC_QUERYBUF
+ * (identical to the cookie used to mmap() the buffer to userspace). All
+ * reserved fields must be set to zero. The field reserved0 is expected to
+ * become a structure 'type' allowing an alternative layout of the structure
+ * content. Therefore this field should not be used for any other extensions.
+ */
+struct v4l2_exportbuffer {
+        __u32           type; /* enum v4l2_buf_type */
+        __u32           index;
+        __u32           plane;
+        __u32           flags;
+        __s32           fd;
+        __u32           reserved[11];
+};
+
 /*
  *      O V E R L A Y   P R E V I E W
  */
@@ -1895,6 +1922,7 @@ struct v4l2_create_buffers {
 #define VIDIOC_S_FBUF            _IOW('V', 11, struct v4l2_framebuffer)
 #define VIDIOC_OVERLAY           _IOW('V', 14, int)
 #define VIDIOC_QBUF             _IOWR('V', 15, struct v4l2_buffer)
+#define VIDIOC_EXPBUF           _IOWR('V', 16, struct v4l2_exportbuffer)
 #define VIDIOC_DQBUF            _IOWR('V', 17, struct v4l2_buffer)
 #define VIDIOC_STREAMON          _IOW('V', 18, int)
 #define VIDIOC_STREAMOFF         _IOW('V', 19, int)