static void virtio_serial_port_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *k = DEVICE_CLASS(klass);

    set_bit(DEVICE_CATEGORY_INPUT, k->categories);
    k->bus_type = TYPE_VIRTIO_SERIAL_BUS;
    k->realize = virtser_port_device_realize;
    k->unrealize = virtser_port_device_unrealize;
    k->props = virtser_props;
}