[media] V4L: Add camera exposure metering control

The V4L2_CID_EXPOSURE_METERING control allows to determine
a method used by the camera for measuring the amount of light
available for automatic exposure.

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>

3 files changed, 46 insertions, 0 deletions

diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index 8fccfe1b2058..e8c63e04741f 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -2864,6 +2864,35 @@ exposure time and/or aperture.</para></entry>
           </row>
           <row><entry></entry></row>
 
+          <row id="v4l2-exposure-metering">
+            <entry spanname="id"><constant>V4L2_CID_EXPOSURE_METERING</constant>&nbsp;</entry>
+            <entry>enum&nbsp;v4l2_exposure_metering</entry>
+          </row><row><entry spanname="descr">Determines how the camera measures
+the amount of light available for the frame exposure. Possible values are:</entry>
+          </row>
+          <row>
+            <entrytbl spanname="descr" cols="2">
+              <tbody valign="top">
+                <row>
+                  <entry><constant>V4L2_EXPOSURE_METERING_AVERAGE</constant>&nbsp;</entry>
+                  <entry>Use the light information coming from the entire frame
+and average giving no weighting to any particular portion of the metered area.
+                  </entry>
+                </row>
+                <row>
+                  <entry><constant>V4L2_EXPOSURE_METERING_CENTER_WEIGHTED</constant>&nbsp;</entry>
+                  <entry>Average the light information coming from the entire frame
+giving priority to the center of the metered area.</entry>
+                </row>
+                <row>
+                  <entry><constant>V4L2_EXPOSURE_METERING_SPOT</constant>&nbsp;</entry>
+                  <entry>Measure only very small area at the center of the frame.</entry>
+                </row>
+              </tbody>
+            </entrytbl>
+          </row>
+          <row><entry></entry></row>
+
           <row>
             <entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant>&nbsp;</entry>
             <entry>integer</entry>
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index debaf9fb9004..55dd813b7341 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -230,6 +230,12 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
                 "Aperture Priority Mode",
                 NULL
         };
+        static const char * const camera_exposure_metering[] = {
+                "Average",
+                "Center Weighted",
+                "Spot",
+                NULL
+        };
         static const char * const colorfx[] = {
                 "None",
                 "Black & White",
@@ -434,6 +440,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
                 return camera_power_line_frequency;
         case V4L2_CID_EXPOSURE_AUTO:
                 return camera_exposure_auto;
+        case V4L2_CID_EXPOSURE_METERING:
+                return camera_exposure_metering;
         case V4L2_CID_COLORFX:
                 return colorfx;
         case V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE:
@@ -632,6 +640,7 @@ const char *v4l2_ctrl_get_name(u32 id)
         case V4L2_CID_IMAGE_STABILIZATION:      return "Image Stabilization";
         case V4L2_CID_ISO_SENSITIVITY:          return "ISO Sensitivity";
         case V4L2_CID_ISO_SENSITIVITY_AUTO:     return "ISO Sensitivity, Auto";
+        case V4L2_CID_EXPOSURE_METERING:        return "Exposure, Metering Mode";
 
         /* FM Radio Modulator control */
         /* Keep the order of the 'case's the same as in videodev2.h! */
@@ -783,6 +792,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
         case V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE:
         case V4L2_CID_JPEG_CHROMA_SUBSAMPLING:
         case V4L2_CID_ISO_SENSITIVITY_AUTO:
+        case V4L2_CID_EXPOSURE_METERING:
                 *type = V4L2_CTRL_TYPE_MENU;
                 break;
         case V4L2_CID_LINK_FREQ:
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 593a1bd33111..a3e47ad60a6d 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -1733,6 +1733,13 @@ enum v4l2_iso_sensitivity_auto_type {
         V4L2_ISO_SENSITIVITY_AUTO               = 1,
 };
 
+#define V4L2_CID_EXPOSURE_METERING              (V4L2_CID_CAMERA_CLASS_BASE+25)
+enum v4l2_exposure_metering {
+        V4L2_EXPOSURE_METERING_AVERAGE          = 0,
+        V4L2_EXPOSURE_METERING_CENTER_WEIGHTED  = 1,
+        V4L2_EXPOSURE_METERING_SPOT             = 2,
+};
+
 /* FM Modulator class control IDs */
 #define V4L2_CID_FM_TX_CLASS_BASE               (V4L2_CTRL_CLASS_FM_TX | 0x900)
 #define V4L2_CID_FM_TX_CLASS                    (V4L2_CTRL_CLASS_FM_TX | 1)