Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
61
Address Translation Unit (PCI-X)—Intel
®
81341 and 81342
2.2.1.1
Inbound Address Translation
The ATU allows external PCI bus initiators to directly access the internal bus. These PCI
bus initiators can read or write 81341 and 81342 memory-mapped registers or 81341
and 81342 local memory space. The process of inbound address translation involves
two steps:
1. Address Detection.
a. Determine when the 32-bit PCI address (64-bit PCI address during DACs) is
within the address windows defined for the inbound ATU.
b. Claim the PCI transaction with medium DEVSEL# timing in the conventional PCI
mode and with Decode A DEVSEL# timing in the PCI-X mode.
2. Address Translation.
a. Translate the 32-bit PCI address (lower 32-bit PCI address during DACs) to a 36-
bit 81341 and 81342 internal bus address.
The ATU uses the following registers in inbound address window 0 translation:
• Inbound ATU Base Address Register 0
• Inbound ATU Limit Register 0
• Inbound ATU Translate Value Register 0
• Inbound ATU Upper Translate Value Register 0
The ATU uses the following registers in inbound address window 1 translation:
• Inbound ATU Base Address Register 1
• Inbound ATU Limit Register 1
• Inbound ATU Translate Value Register 1
• Inbound ATU Upper Translate Value Register 1
The ATU uses the following registers in inbound address window 2 translation:
• Inbound ATU Base Address Register 2
• Inbound ATU Limit Register 2
• Inbound ATU Translate Value Register 2
• Inbound ATU Upper Translate Value Register 2
The ATU uses the following registers in inbound address window 3 translation:
• Inbound ATU Base Address Register 3
• Inbound ATU Limit Register 3
• Inbound ATU Translate Value Register 3
• Inbound ATU Upper Translate Value Register 3
Inbound address detection is determined from the 32-bit PCI address, (64-bit PCI
address during DACs) the base address register and the limit register. In the case of
DACs none of the upper 32-bits of the address is masked during address comparison.
The algorithm for detection is:
Equation 1. Inbound Address Detection
When PCI_Address [31:0] & Limit_Register[31:0] == Base_Register[31:0] and
PCI_Address [63:32] == Base_Register[63:32] (for DACs only) the PCI Address is claimed by the Inbound
ATU.