Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
141
Address Translation Unit (PCI-X)—Intel
®
81341 and 81342
2.12
Embedded Bridge Functionality
The dual interface 81341 and 81342 provides two Address Translation Units: the ATUE
provides a PCI Express interface, and the ATUX provides a PCI/PCIX interface. The two
ATUs are internally connected via the south internal bus.
The two ATUs can be setup and used as an embedded bridge (non-transparent bridge).
For example, the dual interface 81341 and 81342 can be used to bridge a PCI Express
device and a PCI-X device in a system. Both ATUs support endpoint mode and root
complex or central resource mode capabilities. Therefore, either ATU can be connected
upstream or downstream in a system.
shows the possible configurations of
the dual interface 81341 and 81342.
To allow PCI transactions to flow between the two PCI interfaces of the dual interface
81341 and 81342 in a bidirectional manner, each of the ATUs must have at least one of
its Inbound Address Translation Windows mapped to one of the other ATU’s Outbound
Address Translation Windows. Refer to
Section 2.2.2, “Outbound Transactions- Single
Address Cycle (SAC) Internal Bus Transactions” on page 72
that explain how the
Inbound and Outbound address translation windows operate. Below are few examples
that demonstrate how the ATUs may be programmed to operate as an embedded
bridge.
Figure 15. Intel
®
81341 and 81342 I/O Processors PCI Interface Configuration Examples
ATUX
ATUE
ATUE
ATUX
Upstream
( Endpoint)
Upstream
( Endpoint)
Downstream
( Root Complex)
Downstream
( Central Resource
)
ATUE
ATUX
Downstream
( Root Complex)
Downstream
( Central Resource
)
Internal Bus
Internal Bus
Internal Bus
PCI Express
PCI/ PCI-X
PCI/ PCI-X
PCI Express
PCI/ PCI-X
PCI Express
B6175-01