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AMD-761™ System Controller Programmer’s Interface
Chapter 2
AMD-761™ System Controller Software/BIOS Design Guide
24081D—February 2002
Preliminary Information
Programming Notes
Bit Definitions
Configuration Address Register Type 0 (I/O:0CF8)
Bit
Name
Function
31
Config_En
Configuration Enable
0 = PCI configuration cycles are not generated.
1 = Accesses to the Configuration Data and Address registers are converted to
configuration cycles on the PCI.
30–24
Reserved
Reserved
23—16
PCI_Bus_Num
PCI Bus Number
This bit field defines which PCI bus in the system is referenced with this address. The
AMD-761™ system controller logically implements two PCI buses. The main PCI bus
normally enumerates as bus 0 and the AGP bus enumerates as bus 1.
15—11
Dev_Num
Device Number
This bit field defines which device is accessed in the system. Devices are assigned numbers
in a system by tying the device IDSEL wire to a specific PCI AD wire. The AMD-761 system
controller decodes this field and asserts the appropriate AD wire during the address phase
to select the defined device. In the AMD-761 system controller there are two “hard-wired”
device numbers for the host to PCI bridge (0b00000) and P2P bridge (0b00001).
10—8
Func_Num
Function Number
This bit field defines which function is accessed in a given device. The AMD-761 system
controller responds to function 0 only (0b000) by default. Function 1 (DDR PDL registers)
can be enabled via writing to the PCI Control register (Dev 0:F0:0x4C) as described on
page 47.
7—2
Reg_Num
Register Number
This bit field defines which specific PCI register is accessed in the device and function
specified above. The register numbers for the AMD-761 system controller device 0 are
listed in Table 6, “Device 0, Function 0 Configuration Register Map,” on page 27. The
register numbers for the AMD-761 device 1 are listed in Table 15, “Device 1 Configuration
Register Map,” on page 117.
1—0
Reserved
Reserved