libcamera: camera_manager, pipeline_handler: allow retrieving cameras by device numbers

The V4L2 compatibility layer will need a way to map device numbers to
libcamera Camera instances. Expose a method in the camera manager to
retrieve Camera instances by devnum. The mapping from device numbers to
Camera instances is optionally declared by pipeline handlers when they
register cameras with the camera manager.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 5badf31c..698dd525 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -7,6 +7,8 @@
 
 #include "pipeline_handler.h"
 
+#include <sys/sysmacros.h>
+
 #include <libcamera/buffer.h>
 #include <libcamera/camera.h>
 #include <libcamera/camera_manager.h>
@@ -438,19 +440,26 @@ void PipelineHandler::completeRequest(Camera *camera, Request *request)
  * \brief Register a camera to the camera manager and pipeline handler
  * \param[in] camera The camera to be added
  * \param[in] data Pipeline-specific data for the camera
+ * \param[in] devnum Device number of the camera (optional)
  *
  * This method is called by pipeline handlers to register the cameras they
  * handle with the camera manager. It associates the pipeline-specific \a data
  * with the camera, for later retrieval with cameraData(). Ownership of \a data
  * is transferred to the PipelineHandler.
+ *
+ * \a devnum is the device number (as returned by makedev) that the \a camera
+ * is to be associated with. This is for the V4L2 compatibility layer to map
+ * device nodes to Camera instances based on the device number
+ * registered by this method in \a devnum.
  */
 void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera,
-				     std::unique_ptr<CameraData> data)
+				     std::unique_ptr<CameraData> data,
+				     dev_t devnum)
 {
 	data->camera_ = camera.get();
 	cameraData_[camera.get()] = std::move(data);
 	cameras_.push_back(camera);
-	manager_->addCamera(std::move(camera));
+	manager_->addCamera(std::move(camera), devnum);
 }
 
 /**