BCE_REG_MBOX_REPLY
lo = bus_read_4(mb->reg, BCE_REG_MBOX_REPLY);
hi = bus_read_4(mb->reg, BCE_REG_MBOX_REPLY + 4);
bus_read_4(mb->reg, BCE_REG_MBOX_REPLY + 8);
bus_read_4(mb->reg, BCE_REG_MBOX_REPLY + 12);