Pci Target Interface Supported Commands - Intel IXP45X Developer's Manual

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PCI Controller—Intel IXP45X and Intel
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.
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
Table 195.

PCI Target Interface Supported Commands

PCI Byte Enables
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.
August 2006
Order Number: 306262-004US
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IXP46X Product Line of Network Processors
Table 195 lists the supported command types.
Command Type
0x0 Interrupt Acknowledge
0x1 Special Cycle
0x2 I/O Read
0x3 I/O Write
0x4 Reserved
0x5 Reserved
0x6 Memory Read
0x7 Memory Write
0x8 Reserved
0x9 Reserved
0xa Configuration Read
0xb Configuration Write
0xc Memory Read Multiple
0xd Dual Address Cycle
0xe Memory Read Line
0xf Memory Write and Invalidate
not supported
not supported
supported
supported
supported
supported
supported
supported
Converted to Memory
Read
not supported
Converted to Memory
Read
converted to Memory
Write
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Intel IXP45X and Intel IXP46X Product Line of Network Processors
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