Specifications

2008 Advanced Micro Devices Inc.

Sample Programs

AMD SB600 BIOS Developer’s Guide (Public Version) Proprietary

Page 55

14 Sample Programs

14.1 SB600 Register Initialization on Power-Up

14.1.1 Initialization of PCI IRQ Routing Before Resource Allocation

The PCI IRQs are programmed using index/data format through registers C00h/C01h. Index 0

through 3, and 9 through 0Ch, are for PCI IRQ lines. Index 4 is for SCI interrupt generated for

ACPI, and Index 5 is for SMBus interrupt.

Sample Program

The following routine initializes all PCI interrupts to zeroes.

PciIrqInit proc near

push ax ; Save the registers used in the routine

push dx

mov ax,00h ; Start with index = 0, data = 0

ClearPciIrq0To5:

mov dx,0C00h ; PCI interrupt index port

out dx,al ; Set index

mov dx,0C01h ; PCI interrupt data port

xchg ah,al ; Get data in AL = 0

out dx,al

xchg ah,al ; AL = Index

inc al ; Point to next index

cmp al, 05h ; Max index in 0 to 5 series

jbe ClearPciIrq0To5

; Initialize for index 9 through 0Ch

mov ax,0009h ; To clear from index 09 to 0Ch