[02/12] v4l: add buffer exporting via dmabuf

This patch adds extension to V4L2 api. It allow to export a mmap buffer as file
descriptor. New ioctl VIDIOC_EXPBUF is added. It takes a buffer offset used by
mmap and return a file descriptor on success.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/media/video/v4l2-compat-ioctl32.c |    1 +
 drivers/media/video/v4l2-dev.c            |    1 +
 drivers/media/video/v4l2-ioctl.c          |    6 ++++++
 include/linux/videodev2.h                 |   26 ++++++++++++++++++++++++++
 include/media/v4l2-ioctl.h                |    2 ++
 5 files changed, 36 insertions(+)

Hi Tomasz,

Thanks for the patch.

On Wednesday 23 May 2012 15:07:25 Tomasz Stanislawski wrote:
> This patch adds extension to V4L2 api. It allow to export a mmap buffer as
> file descriptor. New ioctl VIDIOC_EXPBUF is added. It takes a buffer offset
> used by mmap and return a file descriptor on success.
> 
> Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

Both the API proposal and the patch look good to me. I'll ack this along with 
the update to the V4L2 documentation ;-)

> ---
>  drivers/media/video/v4l2-compat-ioctl32.c |    1 +
>  drivers/media/video/v4l2-dev.c            |    1 +
>  drivers/media/video/v4l2-ioctl.c          |    6 ++++++
>  include/linux/videodev2.h                 |   26 ++++++++++++++++++++++++++
> include/media/v4l2-ioctl.h                |    2 ++
>  5 files changed, 36 insertions(+)
> 
> diff --git a/drivers/media/video/v4l2-compat-ioctl32.c
> b/drivers/media/video/v4l2-compat-ioctl32.c index 5327ad3..45159d9 100644
> --- a/drivers/media/video/v4l2-compat-ioctl32.c
> +++ b/drivers/media/video/v4l2-compat-ioctl32.c
> @@ -954,6 +954,7 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int
> cmd, unsigned long arg) case VIDIOC_S_FBUF32:
>  	case VIDIOC_OVERLAY32:
>  	case VIDIOC_QBUF32:
> +	case VIDIOC_EXPBUF:
>  	case VIDIOC_DQBUF32:
>  	case VIDIOC_STREAMON32:
>  	case VIDIOC_STREAMOFF32:
> diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
> index 5ccbd46..6bf6307 100644
> --- a/drivers/media/video/v4l2-dev.c
> +++ b/drivers/media/video/v4l2-dev.c
> @@ -597,6 +597,7 @@ static void determine_valid_ioctls(struct video_device
> *vdev) SET_VALID_IOCTL(ops, VIDIOC_REQBUFS, vidioc_reqbufs);
>  	SET_VALID_IOCTL(ops, VIDIOC_QUERYBUF, vidioc_querybuf);
>  	SET_VALID_IOCTL(ops, VIDIOC_QBUF, vidioc_qbuf);
> +	SET_VALID_IOCTL(ops, VIDIOC_EXPBUF, vidioc_expbuf);
>  	SET_VALID_IOCTL(ops, VIDIOC_DQBUF, vidioc_dqbuf);
>  	SET_VALID_IOCTL(ops, VIDIOC_OVERLAY, vidioc_overlay);
>  	SET_VALID_IOCTL(ops, VIDIOC_G_FBUF, vidioc_g_fbuf);
> diff --git a/drivers/media/video/v4l2-ioctl.c
> b/drivers/media/video/v4l2-ioctl.c index 31fc2ad..a73b14e 100644
> --- a/drivers/media/video/v4l2-ioctl.c
> +++ b/drivers/media/video/v4l2-ioctl.c
> @@ -212,6 +212,7 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
>  	IOCTL_INFO(VIDIOC_S_FBUF, INFO_FL_PRIO),
>  	IOCTL_INFO(VIDIOC_OVERLAY, INFO_FL_PRIO),
>  	IOCTL_INFO(VIDIOC_QBUF, 0),
> +	IOCTL_INFO(VIDIOC_EXPBUF, 0),
>  	IOCTL_INFO(VIDIOC_DQBUF, 0),
>  	IOCTL_INFO(VIDIOC_STREAMON, INFO_FL_PRIO),
>  	IOCTL_INFO(VIDIOC_STREAMOFF, INFO_FL_PRIO),
> @@ -957,6 +958,11 @@ static long __video_do_ioctl(struct file *file,
>  			dbgbuf(cmd, vfd, p);
>  		break;
>  	}
> +	case VIDIOC_EXPBUF:
> +	{
> +		ret = ops->vidioc_expbuf(file, fh, arg);
> +		break;
> +	}
>  	case VIDIOC_DQBUF:
>  	{
>  		struct v4l2_buffer *p = arg;
> diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> index 51b20f4..e8893a5 100644
> --- a/include/linux/videodev2.h
> +++ b/include/linux/videodev2.h
> @@ -684,6 +684,31 @@ 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 + *
> + * @fd:		file descriptor associated with DMABUF (set by driver)
> + * @mem_offset:	buffer memory offset as returned by VIDIOC_QUERYBUF in
> struct + *		v4l2_buffer::m.offset (for single-plane formats) or
> + *		v4l2_plane::m.offset (for multi-planar formats)
> + * @flags:	flags for newly created file, currently only O_CLOEXEC is
> + *		supported, refer to manual of open syscall for more details
> + *
> + * 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		fd;
> +	__u32		reserved0;
> +	__u32		mem_offset;
> +	__u32		flags;
> +	__u32		reserved[12];
> +};
> +
>  /*
>   *	O V E R L A Y   P R E V I E W
>   */
> @@ -2553,6 +2578,7 @@ 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)
> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
> index d8b76f7..ccd1faa 100644
> --- a/include/media/v4l2-ioctl.h
> +++ b/include/media/v4l2-ioctl.h
> @@ -119,6 +119,8 @@ struct v4l2_ioctl_ops {
>  	int (*vidioc_reqbufs) (struct file *file, void *fh, struct
> v4l2_requestbuffers *b); int (*vidioc_querybuf)(struct file *file, void
> *fh, struct v4l2_buffer *b); int (*vidioc_qbuf)    (struct file *file, void
> *fh, struct v4l2_buffer *b); +	int (*vidioc_expbuf)  (struct file *file,
> void *fh,
> +				struct v4l2_exportbuffer *e);
>  	int (*vidioc_dqbuf)   (struct file *file, void *fh, struct v4l2_buffer
> *b);
> 
>  	int (*vidioc_create_bufs)(struct file *file, void *fh, struct
> v4l2_create_buffers *b);