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
  *

src/libcamera/controls.cpp

@@ -325,6 +325,11 @@ bool operator==(const ControlInfo &lhs, const ControlId &rhs)
 	return lhs.id() == rhs;
 }
 
+/**
+ * \typedef ControlInfoMap
+ * \brief A map of ControlId to ControlInfo
+ */
+
 /**
  * \class ControlList
  * \brief Associate a list of ControlId with their values for a camera

src/libcamera/include/pipeline_handler.h

@@ -14,6 +14,7 @@
 #include <string>
 #include <vector>
 
+#include <libcamera/controls.h>
 #include <libcamera/stream.h>
 
 namespace libcamera {
@@ -41,6 +42,7 @@ public:
 	Camera *camera_;
 	PipelineHandler *pipe_;
 	std::list<Request *> queuedRequests_;
+	ControlInfoMap controlInfo_;
 
 private:
 	CameraData(const CameraData &) = delete;
@@ -60,6 +62,8 @@ public:
 	bool lock();
 	void unlock();
 
+	const ControlInfoMap &controls(Camera *camera);
+
 	virtual CameraConfiguration *generateConfiguration(Camera *camera,
 		const StreamRoles &roles) = 0;
 	virtual int configure(Camera *camera, CameraConfiguration *config) = 0;

src/libcamera/pipeline_handler.cpp

@@ -88,6 +88,14 @@ LOG_DEFINE_CATEGORY(Pipeline)
  * PipelineHandler::completeRequest()
  */
 
+/**
+ * \var CameraData::controlInfo_
+ * \brief The set of controls supported by the camera
+ *
+ * The control information shall be initialised by the pipeline handler when
+ * creating the camera, and shall not be modified afterwards.
+ */
+
 /**
  * \class PipelineHandler
  * \brief Create and manage cameras based on a set of media devices
@@ -217,6 +225,17 @@ void PipelineHandler::unlock()
 		media->unlock();
 }
 
+/**
+ * \brief Retrieve the list of controls for a camera
+ * \param[in] camera The camera
+ * \return A ControlInfoMap listing the controls support by \a camera
+ */
+const ControlInfoMap &PipelineHandler::controls(Camera *camera)
+{
+	CameraData *data = cameraData(camera);
+	return data->controlInfo_;
+}
+
 /**
  * \fn PipelineHandler::generateConfiguration()
  * \brief Generate a camera configuration for a specified camera