How to implement a multi-function device?

I have a 'servo' device which contains UARTs and reset control. I have manged to create a Servo resource and a ServoDriver for it:

class Servo(Resource):
    """"This resource describes a servo board with servod server

    This provides serial consoles along with reset control

    Args:
        serial (str): serial number of the servo device
        port (int): port index to use for servod process
    """
    serial = attr.ib(validator=attr.validators.instance_of(str))
    port = attr.ib(validator=attr.validators.instance_of(int),
                    converter=int)


@target_factory.reg_driver
@attr.s(eq=False)
class ServoDriver(ConsoleExpectMixin, Driver, ConsoleProtocol, ResetProtocol):
    """Provides access to servo features including console and reset

    Args:
        bindings (dict): driver to use with
    """
    bindings = {
        "servo": {"Servo", "NetworkServo"},
    }

but I am not sure how to connect up the console. I get this error when using the labgrid-client 'console' command:

labgrid.exceptions.NoResourceFoundError: no NetworkSerialPort resource found in Target(name='try', env=Environment(config_file='/vid/software/devel/ubtest/lab/env_rpi_try.cfg'), var_dict=None)

This seems obvious enough, but how can I create the serial port? I don't see how multi-function devices can be implemented?

Start with the Servo resource and ServoDriver bindings, then trace how labgrid-client's console command resolves NetworkSerialPort on the Target. Check the Environment configuration referenced by env_rpi_try.cfg and determine how the UART should be represented alongside reset control. Done means the configured target exposes a serial resource that the console command can resolve without NoResourceFoundError.