'Returns config spec for adding a disk controller.'

def _create_controller_config_spec(self, adapter_type):

    cf = self._session.vim.client.factory
    controller_type = ControllerType.get_controller_type(adapter_type)
    controller_device = cf.create(('ns0:%s' % controller_type))
    controller_device.key = (-100)
    controller_device.busNumber = 0
    if ControllerType.is_scsi_controller(controller_type):
        controller_device.sharedBus = 'noSharing'
    controller_spec = cf.create('ns0:VirtualDeviceConfigSpec')
    controller_spec.operation = 'add'
    controller_spec.device = controller_device
    return controller_spec
