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Address Translation and Mapping

MPC8540 PowerQUICC III Integrated Host Processor Reference Manual, Rev. 1

Freescale Semiconductor

2-9

The PCI/PCI-X controller has four outbound ATMU windows plus a default window. The

PCI/PCI-X outbound ATMU registers include an extended translation address register so that up

to 64 bits of external address space can be supported. See Section 16.3.1.2, “PCI/X ATMU

Outbound Registers,” for a detailed description of the PCI/PCI-X outbound ATMU windows.

2.2.5

Inbound Address Translation and Mapping Windows

Inbound address translation and mapping refers to the translation of an address from the external

address space of an I/O interface (such as PCI or RapidIO address space) to the local address space

understood by the internal interfaces of the MPC8540. It also refers to the mapping of transactions

to a particular target interface and the assignment of transaction attributes. Both the RapidIO

controller and the PCI/PCI-X controller have inbound address translation and mapping units

(ATMUs).

2.2.5.1

RapidIO Inbound ATMU

The RapidIO controller has four inbound ATMU windows plus a default. If the inbound

transaction’s address does not hit any of the four inbound ATMU windows, the translation actions

defined by the default window are used. The default window is always enabled. See

Section 17.3.2.2, “ATMU Registers,” for a detailed description of the RapidIO inbound ATMU

windows.

2.2.5.2

PCI/PCI-X Inbound ATMU

The PCI/PCI-X controller has three general inbound ATMU windows plus a dedicated window for

memory mapped configuration accesses (PCSRBAR). These windows have a one-to-one

correspondence with the base address registers in the PCI/PCI-X programming model. Updating

one automatically updates the other. There is no default inbound window; if a PCI/PCI-X address

does not match one of the inbound ATMU windows, the MPC8540 does not respond with an

assertion of PCI_DEVSEL. See Section 16.3.1.3, “PCI/X ATMU Inbound Registers,” for a

detailed description of the PCI/PCI-X inbound ATMU windows.

2.2.5.3

Illegal Interaction Between Inbound ATMUs and Local Access

Windows

Since both local access windows and inbound ATMUs map transactions to a target interface, it is

essential that they not contradict one another. For instance, it is a programming error to have an

inbound ATMU map a transaction to the DDR SDRAM memory controller (target interface

0b1111) if the resulting translated local address is mapped to PCI (target interface 0b0000) by a

local access window. Such a programming error may result in unpredictable system deadlocks.

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