[quote user="Naoki Kawada"]I don't know what masters are belonging to exp (Expansion Initiator)[/quote]
Many recent SoC have references to an Expansion Port, with basically no info other than that it's a 128-bit initiator and 128-bit target on the L3-Fast interconnect. My guess would be that it's something similar to the OMAP4's chip-to-chip interface, meant to allow an external chip direct interconnect access (e.g. to share RAM). In any case, the lack of documentation makes evident it's not available except probably for sufficiently big customers.