[media] V4L: Add camera 3A lock control

The V4L2_CID_3A_LOCK bitmask control allows applications to pause
or resume the automatic exposure, focus and wite balance adjustments.
It can be used, for example, to lock the 3A adjustments right before
a still image is captured, for pre-focus, etc.
The applications can control each of the algorithms independently,
through a corresponding control bit, if driver allows that.

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 ad0d53d3ffdd..f38f06169795 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -3301,6 +3301,45 @@ lens-distortion correction.</entry>
           </row>
           <row><entry></entry></row>
 
+          <row>
+            <entry spanname="id"><constant>V4L2_CID_3A_LOCK</constant></entry>
+            <entry>bitmask</entry>
+          </row>
+          <row>
+            <entry spanname="descr">This control locks or unlocks the automatic
+focus, exposure and white balance. The automatic adjustments can be paused
+independently by setting the corresponding lock bit to 1. The camera then retains
+the settings until the lock bit is cleared. The following lock bits are defined:
+</entry>
+          </row>
+          <row>
+            <entrytbl spanname="descr" cols="2">
+              <tbody valign="top">
+                <row>
+                  <entry><constant>V4L2_LOCK_EXPOSURE</constant></entry>
+                  <entry>Automatic exposure adjustments lock.</entry>
+                </row>
+                <row>
+                  <entry><constant>V4L2_LOCK_WHITE_BALANCE</constant></entry>
+                  <entry>Automatic white balance adjustments lock.</entry>
+                </row>
+                <row>
+                  <entry><constant>V4L2_LOCK_FOCUS</constant></entry>
+                  <entry>Automatic focus lock.</entry>
+                </row>
+              </tbody>
+            </entrytbl>
+          </row>
+          <row><entry spanname="descr">
+When a given algorithm is not enabled, drivers should ignore requests
+to lock it and should return no error. An example might be an application
+setting bit <constant>V4L2_LOCK_WHITE_BALANCE</constant> when the
+<constant>V4L2_CID_AUTO_WHITE_BALANCE</constant> control is set to
+<constant>FALSE</constant>. The value of this control may be changed
+by exposure, white balance or focus controls.</entry>
+          </row>
+          <row><entry></entry></row>
+
         </tbody>
       </tgroup>
     </table>
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index d4dc8ba7b755..a47b29270ba3 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -661,6 +661,7 @@ const char *v4l2_ctrl_get_name(u32 id)
         case V4L2_CID_ISO_SENSITIVITY_AUTO:     return "ISO Sensitivity, Auto";
         case V4L2_CID_EXPOSURE_METERING:        return "Exposure, Metering Mode";
         case V4L2_CID_SCENE_MODE:               return "Scene Mode";
+        case V4L2_CID_3A_LOCK:                  return "3A Lock";
 
         /* FM Radio Modulator control */
         /* Keep the order of the 'case's the same as in videodev2.h! */
@@ -849,6 +850,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
                 break;
         case V4L2_CID_FLASH_FAULT:
         case V4L2_CID_JPEG_ACTIVE_MARKER:
+        case V4L2_CID_3A_LOCK:
                 *type = V4L2_CTRL_TYPE_BITMASK;
                 break;
         case V4L2_CID_MIN_BUFFERS_FOR_CAPTURE:
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 092bf5aaf348..a9b03ae44037 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -1758,6 +1758,11 @@ enum v4l2_scene_mode {
         V4L2_SCENE_MODE_TEXT                    = 13,
 };
 
+#define V4L2_CID_3A_LOCK                        (V4L2_CID_CAMERA_CLASS_BASE+27)
+#define V4L2_LOCK_EXPOSURE                      (1 << 0)
+#define V4L2_LOCK_WHITE_BALANCE                 (1 << 1)
+#define V4L2_LOCK_FOCUS                         (1 << 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)