Man page 9 : transport_add_device

transport_add_device - declare a new dev for transport class association

void transport_add_device(struct device *  dev );

dev
    the generic device representing the entity being added

Usually, dev represents some component in the HBA system (either the HBA itself or a device remote across the HBA bus). This routine is simply a trigger point used to add the device to the system and register attributes for it.