[media] v4l: subdev: Events support

Provide v4l2_subdevs with v4l2_event support. Subdev drivers only need very
little to support events.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: David Cohen <dacohen@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 3276065..0f9937b 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -37,6 +37,8 @@
 
 struct v4l2_device;
 struct v4l2_ctrl_handler;
+struct v4l2_event_subscription;
+struct v4l2_fh;
 struct v4l2_subdev;
 struct tuner_setup;
 
@@ -161,6 +163,10 @@
 	int (*s_power)(struct v4l2_subdev *sd, int on);
 	int (*interrupt_service_routine)(struct v4l2_subdev *sd,
 						u32 status, bool *handled);
+	int (*subscribe_event)(struct v4l2_subdev *sd, struct v4l2_fh *fh,
+			       struct v4l2_event_subscription *sub);
+	int (*unsubscribe_event)(struct v4l2_subdev *sd, struct v4l2_fh *fh,
+				 struct v4l2_event_subscription *sub);
 };
 
 /* s_mode: switch the tuner to a specific tuner mode. Replacement of s_radio.
@@ -437,6 +443,8 @@
 #define V4L2_SUBDEV_FL_IS_SPI			(1U << 1)
 /* Set this flag if this subdev needs a device node. */
 #define V4L2_SUBDEV_FL_HAS_DEVNODE		(1U << 2)
+/* Set this flag if this subdev generates events. */
+#define V4L2_SUBDEV_FL_HAS_EVENTS		(1U << 3)
 
 /* Each instance of a subdev driver should create this struct, either
    stand-alone or embedded in a larger struct.
@@ -460,6 +468,8 @@
 	void *host_priv;
 	/* subdev device node */
 	struct video_device devnode;
+	/* number of events to be allocated on open */
+	unsigned int nevents;
 };
 
 #define vdev_to_v4l2_subdev(vdev) \