Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
55
Address Translation Unit (PCI-X)—Intel
®
81341 and 81342
2.0
Address Translation Unit (PCI-X)
This chapter describes the operation modes, setup, and implementation of the module
which interfaces between the PCI bus and the Intel
®
81341 and 81342 I/O Processors
(81341 and 81342) internal bus.
2.1
Overview
As indicated in
, the Address Translation Unit (ATU) — the interface between
the PCI bus and the on-chip internal bus — consists of the Address Translation Unit
(ATU) and the Expansion ROM Unit.
The ATU supports both inbound and outbound address translation. The ATU provides
access between the PCI bus and the 81341 and 81342 internal bus.
Transactions initiated on the PCI bus and targeted at the 81341 and 81342 internal bus
are referred to as inbound transactions (PCI to internal bus). Transactions initiated on
the 81341 and 81342 internal bus and targeted at the PCI bus are referred to as
outbound transactions (internal bus to PCI). The ATU accepts multiple inbound or
outbound transactions and processes them simultaneously.
During inbound transactions, the ATU converts PCI addresses (initiated by a PCI bus
master) to Internal Bus Addresses and initiates the data transfer on the 81341 and
81342 internal bus. During outbound transactions, the ATU converts internal bus
addresses to PCI addresses and initiates the data transfer on the PCI bus.
The Expansion ROM provides the PCI mechanism for downloading device/board driver
code during system boot sequence. It consists of a separate inbound address range
which accesses a Flash EPROM device connected through the 81341 and 81342
memory controller. Refer to the PCI Local Bus Specification, Revision 2.3 for details of
Expansion ROM usage.
The Address Translation Unit and the Expansion ROM Translation Unit represent a single
function of the multi-function 81341 and 81342 PCI device.
The ATU supports the following PCI operating modes and bus widths delivering up to
2133 Mbytes/sec of bandwidth:
— Conventional Modes: PCI 33, PCI 66
— PCI-X Modes: Mode 1 (PCI-X 66, PCI-X 133), Mode 2 (PCI-X 266)
— Bus Widths: 64-bit, 32-bit
In Mode 2, all transaction phases are ECC protected (when enabled). In the remaining
PCI-X and Conventional modes supported by 81341 and 81342, all transaction phases
are parity protected (when enabled).
On the internal interface, the ATU implements the 81341 and 81342 internal bus
protocol which provides for a maximum of 4800 Mbytes/sec of bandwidth.
The 81341 and 81342 meets the standard requirements to be considered “Hot-Swap
Silicon” detailed in the Compact PCI Hot-Swap Specification, Revision 2.1.