libcamera: pipeline_handler: Add const version of cameraData()

Add a version of cameraData() that returns a const pointer and mark it
as a const operation. The assert in the non-const version of the
function already enforces that a std::map::at() operation would always
succeed so there is no change in operation from the non-const version.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/pipeline_handler.h

@@ -97,6 +97,7 @@ protected:
 	virtual int queueRequestDevice(Camera *camera, Request *request) = 0;
 
 	CameraData *cameraData(const Camera *camera);
+	const CameraData *cameraData(const Camera *camera) const;
 
 	CameraManager *manager_;
 

src/libcamera/pipeline_handler.cpp

@@ -601,6 +601,19 @@ CameraData *PipelineHandler::cameraData(const Camera *camera)
 	return cameraData_[camera].get();
 }
 
+/**
+ * \brief Retrieve the pipeline-specific data associated with a Camera
+ * \param[in] camera The camera whose data to retrieve
+ * \sa cameraData()
+ * \return A const pointer to the pipeline-specific data passed to
+ * registerCamera().
+ */
+const CameraData *PipelineHandler::cameraData(const Camera *camera) const
+{
+	ASSERT(cameraData_.count(camera));
+	return cameraData_.at(camera).get();
+}
+
 /**
  * \var PipelineHandler::manager_
  * \brief The Camera manager associated with the pipeline handler