media: uvcvideo: Add a metadata device node

Some UVC video cameras contain metadata in their payload headers. This
patch extracts that data, adding more clock synchronisation information,
on both bulk and isochronous endpoints and makes it available to the user
space on a separate video node, using the V4L2_CAP_META_CAPTURE capability
and the V4L2_BUF_TYPE_META_CAPTURE buffer queue type. By default, only the
V4L2_META_FMT_UVC pixel format is available from those nodes. However,
cameras can be added to the device ID table to additionally specify their
own metadata format, in which case that format will also become available
from the metadata node.

[Use put_unaligned instead of __put_unaligned_cpu64]
[Use put_unaligned for the sof field as well]

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h
index e80b4655d8cd..020714d2c5bd 100644
--- a/include/uapi/linux/uvcvideo.h
+++ b/include/uapi/linux/uvcvideo.h
@@ -68,4 +68,30 @@ struct uvc_xu_control_query {
 #define UVCIOC_CTRL_MAP         _IOWR('u', 0x20, struct uvc_xu_control_mapping)
 #define UVCIOC_CTRL_QUERY       _IOWR('u', 0x21, struct uvc_xu_control_query)
 
+/*
+ * Metadata node
+ */
+
+/**
+ * struct uvc_meta_buf - metadata buffer building block
+ * @ns          - system timestamp of the payload in nanoseconds
+ * @sof         - USB Frame Number
+ * @length      - length of the payload header
+ * @flags       - payload header flags
+ * @buf         - optional device-specific header data
+ *
+ * UVC metadata nodes fill buffers with possibly multiple instances of this
+ * struct. The first two fields are added by the driver, they can be used for
+ * clock synchronisation. The rest is an exact copy of a UVC payload header.
+ * Only complete objects with complete buffers are included. Therefore it's
+ * always sizeof(meta->ts) + sizeof(meta->sof) + meta->length bytes large.
+ */
+struct uvc_meta_buf {
+        __u64 ns;
+        __u16 sof;
+        __u8 length;
+        __u8 flags;
+        __u8 buf[];
+} __packed;
+
 #endif