[media] V4L: Add MATRIX option to V4L2_CID_EXPOSURE_METERING control

This patch adds a menu option to the V4L2_CID_EXPOSURE_METERING
control for multi-zone metering.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/v4l/controls.xml

@@ -3142,6 +3142,13 @@ giving priority to the center of the metered area.</entry>
 		  <entry><constant>V4L2_EXPOSURE_METERING_SPOT</constant>&nbsp;</entry>
 		  <entry>Measure only very small area at the center of the frame.</entry>
 		</row>
+		<row>
+		  <entry><constant>V4L2_EXPOSURE_METERING_MATRIX</constant>&nbsp;</entry>
+		  <entry>A multi-zone metering. The light intensity is measured
+in several points of the frame and the the results are combined. The
+algorithm of the zones selection and their significance in calculating the
+final value is device dependant.</entry>
+		</row>
 	      </tbody>
 	    </entrytbl>
 	  </row>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -234,6 +234,7 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
 		"Average",
 		"Center Weighted",
 		"Spot",
+		"Matrix",
 		NULL
 	};
 	static const char * const camera_auto_focus_range[] = {

include/uapi/linux/v4l2-controls.h

@@ -658,6 +658,7 @@ enum v4l2_exposure_metering {
 	V4L2_EXPOSURE_METERING_AVERAGE		= 0,
 	V4L2_EXPOSURE_METERING_CENTER_WEIGHTED	= 1,
 	V4L2_EXPOSURE_METERING_SPOT		= 2,
+	V4L2_EXPOSURE_METERING_MATRIX		= 3,
 };
 
 #define V4L2_CID_SCENE_MODE			(V4L2_CID_CAMERA_CLASS_BASE+26)