diff --git a/reactos/drivers/wdm/audio/backpln/portcls/port_topology.c b/reactos/drivers/wdm/audio/backpln/portcls/port_topology.c
index 6ec3777e516..3a35ed5fb2d 100644
--- a/reactos/drivers/wdm/audio/backpln/portcls/port_topology.c
+++ b/reactos/drivers/wdm/audio/backpln/portcls/port_topology.c
@@ -1,11 +1,195 @@
 #include "private.h"
 
+typedef struct
+{
+    IPortTopologyVtbl *lpVtbl;
+
+    LONG ref;
+    BOOL bInitialized;
+
+    PMINIPORTTOPOLOGY Miniport;
+    PDEVICE_OBJECT pDeviceObject;
+    PRESOURCELIST pResourceList;
+
+}IPortTopologyImpl;
+
+const GUID IID_IMiniportTopology;
+const GUID IID_IPortTopology;
+
+//---------------------------------------------------------------
+// IUnknown interface functions
+//
+
+NTSTATUS
+NTAPI
+IPortTopology_fnQueryInterface(
+    IPortTopology* iface,
+    IN  REFIID refiid,
+    OUT PVOID* Output)
+{
+    IPortTopologyImpl * This = (IPortTopologyImpl*)iface;
+
+    if (IsEqualGUIDAligned(refiid, &IID_IPortTopology) ||
+        IsEqualGUIDAligned(refiid, &IID_IUnknown))
+    {
+        *Output = &This->lpVtbl;
+        _InterlockedIncrement(&This->ref);
+        return STATUS_SUCCESS;
+    }
+
+    return STATUS_UNSUCCESSFUL;
+}
+
+ULONG
+NTAPI
+IPortTopology_fnAddRef(
+    IPortTopology* iface)
+{
+    IPortTopologyImpl * This = (IPortTopologyImpl*)iface;
+
+    return InterlockedIncrement(&This->ref);
+}
+
+ULONG
+NTAPI
+IPortTopology_fnRelease(
+    IPortTopology* iface)
+{
+    IPortTopologyImpl * This = (IPortTopologyImpl*)iface;
+
+    InterlockedDecrement(&This->ref);
+
+    if (This->ref == 0)
+    {
+        ExFreePoolWithTag(This, TAG_PORTCLASS);
+        return 0;
+    }
+    /* Return new reference count */
+    return This->ref;
+}
 
 
+//---------------------------------------------------------------
+// IPort interface functions
+//
+
+NTSTATUS
+NTAPI
+IPortTopology_fnGetDeviceProperty(
+    IN IPortTopology * iface,
+    IN DEVICE_REGISTRY_PROPERTY  DeviceRegistryProperty,
+    IN ULONG  BufferLength,
+    OUT PVOID  PropertyBuffer,
+    OUT PULONG  ReturnLength)
+{
+    IPortTopologyImpl * This = (IPortTopologyImpl*)iface;
+
+    if (!This->bInitialized)
+    {
+        DPRINT("IPortWaveCyclic_fnNewRegistryKey called w/o initiazed\n");
+        return STATUS_UNSUCCESSFUL;
+    }
+
+    return IoGetDeviceProperty(This->pDeviceObject, DeviceRegistryProperty, BufferLength, PropertyBuffer, ReturnLength);
+}
+
+NTSTATUS
+NTAPI
+IPortTopology_fnInit(
+    IN IPortTopology * iface,
+    IN PDEVICE_OBJECT  DeviceObject,
+    IN PIRP  Irp,
+    IN PUNKNOWN  UnknownMiniport,
+    IN PUNKNOWN  UnknownAdapter  OPTIONAL,
+    IN PRESOURCELIST  ResourceList)
+{
+    IMiniportTopology * Miniport;
+    NTSTATUS Status;
+    IPortTopologyImpl * This = (IPortTopologyImpl*)iface;
+
+    if (This->bInitialized)
+    {
+        DPRINT("IPortWaveCyclic_Init called again\n");
+        return STATUS_SUCCESS;
+    }
+
+    Status = UnknownMiniport->lpVtbl->QueryInterface(UnknownMiniport, &IID_IMiniportTopology, (PVOID*)&Miniport);
+    if (!NT_SUCCESS(Status))
+    {
+        DPRINT("IPortWaveCyclic_Init called with invalid IMiniport adapter\n");
+        return STATUS_INVALID_PARAMETER;
+    }
+
+    Status = Miniport->lpVtbl->Init(Miniport, UnknownAdapter, ResourceList, iface);
+    if (!NT_SUCCESS(Status))
+    {
+        DPRINT("IMiniportWaveCyclic_Init failed with %x\n", Status);
+        return Status;
+    }
+
+    /* Initialize port object */
+    This->Miniport = Miniport;
+    This->pDeviceObject = DeviceObject;
+    This->bInitialized = TRUE;
+    This->pResourceList = ResourceList;
+
+    /* increment reference on miniport adapter */
+    Miniport->lpVtbl->AddRef(Miniport);
+    /* increment reference on resource list */
+    ResourceList->lpVtbl->AddRef(ResourceList);
+
+    return STATUS_SUCCESS;
+}
+
+
+NTSTATUS
+NTAPI
+IPortTopology_fnNewRegistryKey(
+    IN IPortTopology * iface,
+    OUT PREGISTRYKEY  *OutRegistryKey,
+    IN PUNKNOWN  OuterUnknown  OPTIONAL,
+    IN ULONG  RegistryKeyType,
+    IN ACCESS_MASK  DesiredAccess,
+    IN POBJECT_ATTRIBUTES  ObjectAttributes  OPTIONAL,
+    IN ULONG  CreateOptions  OPTIONAL,
+    OUT PULONG  Disposition  OPTIONAL)
+{
+    IPortTopologyImpl * This = (IPortTopologyImpl*)iface;
+
+    if (!This->bInitialized)
+    {
+        DPRINT("IPortWaveCyclic_fnNewRegistryKey called w/o initialized\n");
+        return STATUS_UNSUCCESSFUL;
+    }
+    return STATUS_UNSUCCESSFUL;
+}
+
+static IPortTopologyVtbl vt_IPortTopology =
+{
+    /* IUnknown methods */
+    IPortTopology_fnQueryInterface,
+    IPortTopology_fnAddRef,
+    IPortTopology_fnRelease,
+    /* IPort methods */
+    IPortTopology_fnInit,
+    IPortTopology_fnGetDeviceProperty,
+    IPortTopology_fnNewRegistryKey
+};
 
 NTSTATUS
 NewPortTopology(
     OUT PPORT* OutPort)
 {
-    return STATUS_UNSUCCESSFUL;
+    IPortTopologyImpl * This;
+
+    This = ExAllocatePoolWithTag(NonPagedPool, sizeof(IPortTopologyImpl), TAG_PORTCLASS);
+    if (!This)
+        return STATUS_INSUFFICIENT_RESOURCES;
+
+    RtlZeroMemory(This, sizeof(IPortTopologyImpl));
+    This->lpVtbl = &vt_IPortTopology;
+    This->ref = 1;
+    *OutPort = (PPORT)(&This->lpVtbl);
+
+    return STATUS_SUCCESS;
 }