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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—PCI Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Develepor’s Manual
August 2006
506
Order Number: 306262-004US
Bus to the address of the South AHB. The PCI Memory Base Address Register
(PCI_PCIMEMBASE) is used to map the address of direct access PCI memory-mapped
transfers from the address of the South AHB to the address of the PCI Bus.
When the IXP45X/IXP46X network processors are the target of a PCI bus transaction,
the values written or read by external PCI Bus Initiators using the Base Address
Registers contained within the IXP45X/IXP46X network processors must be translated
to an address location within the processors. The configuration of the internal memory
allocation is implemented differently for each of the Base Address Registers (BAR). The
following paragraphs describe the implementation for each of the Base Address
Registers.
For Base Address Registers 0 through 3 — which are used to complete PCI Bus Memory
Cycles Target transactions — the AHB Memory Base Address (PCI_AHBMEMBASE)
register is used to translate PCI Memory Cycle accesses to their appropriate AHB
locations. The AHB Memory Base Address (PCI_AHBMEMBASE) register is used to
determine the upper 8 AHB address bits when an external Initiator on the PCI bus
accesses the memory spaces of the IXP45X/IXP46X network processors. The PCI
Controller can be configured to support four 16-Mbyte locations for PCI Target Memory
Cycle transactions using the AHB Memory Base Address (PCI_AHBMEMBASE) register
and the PCI Base Address Registers.
The AHB Memory Base Address (PCI_AHBMEMBASE) register consists of four 8-bit
fields. Each of these fields corresponds to a PCI Base Address Register
• Bits 31:24 of the AHB Memory Base Address (PCI_AHBMEMBASE) register
corresponds to PCI Base Address 0 and the first 16-Mbyte AHB memory location
(AHB base 0)
• Bits 23:16 of the AHB Memory Base Address (PCI_AHBMEMBASE) register
corresponds to PCI Base Address 1 and the second 16-Mbyte AHB memory location
(AHB base 1)
• Bits 15:8 of the AHB Memory Base Address (PCI_AHBMEMBASE) register
corresponds to PCI Base Address 2 and the third 16-Mbyte AHB memory location
(AHB base 2)
• Bits 7:0 of the AHB Memory Base Address (PCI_AHBMEMBASE) register
corresponds to PCI Base Address 3 and the fourth 16-Mbyte AHB memory location
(AHB base 3).
Base Address Register 4 is used to complete accesses to internal PCI Controller
Configuration and Status registers. (These registers are not the PCI Controller PCI
Configuration Registers.) PCI Base Address Register 4 is used to decode that an access
has been made to the Configuration and Status Register Space. There are no AHB
cycles produced for this type of an access, as all accesses to this Base Address Register
will be internal to the PCI controller. Therefore, an address translation register is not
required.
For Base Address Register 5 — which is used to complete PCI bus I/O cycles — the AHB
I/O Base Address (PCI_AHBIOBASE) register is used to translate I/O PCI accesses to
their appropriate AHB locations. The PCI Controller can be configured to support a
single 256-Byte location for PCI target I/O cycle transactions, using the AHB I/O Base
Address (PCI_AHBIOBASE) register and PCI Base Address Register 5.
The AHB I/O Base Address (PCI_AHBIOBASE) register consists of a single 24-bit field.
The AHB I/O Base Address (PCI_AHBIOBASE) register is used to determine the upper
24 AHB address bits, when an external initiator on the PCI bus accesses the I/O space
of the IXP45X/IXP46X network processors.