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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Develepor’s Manual
Order Number: 306262-004US
495
PCI Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
10.0
PCI Controller
10.1
Introduction
The Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors contains a
32-bit, 66-MHz PCI interface compatible with PCI Version 2.2.
10.2
Overview
The PCI interface is capable of operating as either a host or as an option. The PCI
Controller supports these modes of operation by enabling access to the configuration
register space of the IXP45X/IXP46X network processors, from either the Intel XScale
®
Processor when operating as a host or from an external PCI device using the PCI bus
when configured as an option. Whether configured as a PCI host or PCI option, initiator
or target operations are fully supported by the PCI interface of the IXP45X/IXP46X
network processors.
When the PCI Controller is configured as a host, an internal PCI arbiter may be utilized
to allow up to four devices to be connected to the IXP45X/IXP46X network processors
without the need for an external arbiter. However, even though the internal PCI arbiter
exists, the internal PCI arbiter is not required to be used when the PCI controller is
configured in host or for that matter option mode of operation.The arbiter functionality
is completely independent from the PCI mode of operation. An example connection of
this configuration is contained in
. The PCI arbiter function will allow access to
the PCI bus in a round-robin fashion.
The PCI controller operating as an initiator can generate Memory, I/O, or Configuration
PCI bus cycles. Operating as a target, the PCI Controller can accept Memory, I/O, or
Configuration PCI bus cycles. The PCI Controller also contains two DMA engines to
allow data movement between the PCI bus and the DDRI
SDRAM without the aid of the
Intel XScale processor.
When the PCI Controller is configured as an option, the internal PCI arbiter can be
disabled and REQ0/GNT0 are used to connect to an external arbiter on the PCI bus. An
example of the IXP45X/IXP46X network processors connected in this configuration is
shown in
. The PCI arbiter can be enabled/disabled independently from the
PCI host/option configuration.