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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Develepor’s Manual
Order Number: 306262-004US
523
PCI Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
10.3.2.1
PCI Target Interface
The PCI Target Interface provides read/write access to AHB agents, PCI Controller PCI
Configuration registers (through Configuration cycles), and some PCI Controller CSRs.
The interface performs the PCI target actions in response to external PCI Master
transactions.
lists the supported command types.
The interface does not support the following features:
• Lock cycles
• VGA palette snoop
• Dual address cycles
• Cache-line, wrap-mode addressing
• Configuration Type 1 read/write cycles
10.3.2.1.1
PCI Bus Access to PCI Configuration Registers
An access to PCI Configuration registers occurs when the PCI_IDSEL input is asserted,
the PCI command is a configuration read or write, and PCI_AD[1:0] = 00 indicating a
type 0 configuration cycle. The selected register is indicated by PCI_AD[7:2]. Accesses
are single-word only, the Target Interface will disconnect any burst longer than 1 word.
During reads, byte enables are ignored and the full 32-bit register value is returned.
Read accesses to unimplemented registers complete normally on the bus and return all
zeroes. During writes, the PCI byte enables determine the byte(s) to be written within
the addressed register. Write accesses to unimplemented registers complete normally
on the bus but the data is discarded.
Table 195.
PCI Target Interface Supported Commands
PCI Byte Enables
Command Type
Support
0x0
Interrupt Acknowledge
not supported
0x1
Special Cycle
not supported
0x2
I/O Read
supported
0x3
I/O Write
supported
0x4
Reserved
0x5
Reserved
0x6
Memory Read
supported
0x7
Memory Write
supported
0x8
Reserved
0x9
Reserved
0xa
Configuration Read
supported
0xb
Configuration Write
supported
0xc
Memory Read Multiple
Converted to Memory
Read
0xd
Dual Address Cycle
not supported
0xe
Memory Read Line
Converted to Memory
Read
0xf
Memory Write and Invalidate
converted to Memory
Write