libcamera: camera: Provide a list of ControlInfo

Extend the Camera class to expose the controls it supports. Each
pipeline should generate a list of controls supported by each camera it
creates. These are represented by a ControlInfoMap, and an associated
ControlList of default values.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/camera.cpp

@@ -548,6 +548,18 @@ int Camera::release()
 	return 0;
 }
 
+/**
+ * \brief Retrieve the list of controls supported by the camera
+ *
+ * Camera controls remain constant through the lifetime of the camera.
+ *
+ * \return A ControlInfoMap listing the controls supported by the camera
+ */
+const ControlInfoMap &Camera::controls()
+{
+	return pipe_->controls(this);
+}
+
 /**
  * \brief Retrieve all the camera's stream information
  *