82801CA Datasheet, PDF (280/521 Pages) Intel Corporation – I/O Controller Hub 3-S (ICH3-S)

LPC I/F Bridge Registers (D31:F0)
9.1.10
9.1.11
PMBASE—ACPI Base Address Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Power Well:
40–43h
00000001h
No
Core
Attribute:
Size:
Usage:
R/W
32-bit
ACPI, Legacy
Sets base address for ACPI I/O registers, GPIO registers and TCO I/O registers. Can be mapped
anywhere in the 64 KB I/O space on 128-byte boundaries.
Bit
31:16
15:7
6:1
0
Description
Reserved.
Base Address—R/W. Provides 128 bytes of I/O space for ACPI, GPIO, and TCO logic. This is
placed on a 128-byte boundary.
Reserved.
Resource Indicator—RO. Tied to 1 to indicate I/O space.
ACPI_CNTL—ACPI Control Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Power Well:
44h
00h
No
Core
Attribute:
Size:
Usage:
R/W
8-bit
ACPI, Legacy
Bit
Description
7:5 Reserved.
ACPI Enable (ACPI_EN)—R/W.
0 = Disable.
4 _{1 = Decode of the I/O range pointed to by the ACPI base register is enabled, and the ACPI power}
management function is enabled. Note that the APM power management ranges (B2/B3h) are
always enabled and are not affected by this bit.
3 Reserved.
SCI IRQ Select (SCI_IRQ_SEL)—R/W.
Specifies on which IRQ the SCI will internally appear. If not using the APIC, the SCI must be routed
to IRQ9–11, and that interrupt is not sharable with the SERIRQ stream, but is shareable with other
PCI interrupts. If using the APIC, the SCI can also be mapped to IRQ20-23, and can be shared with
other interrupts.
Bits SCI Map
000 IRQ9
001 IRQ10
2:0
010 IRQ11
011 Reserved
100 IRQ20 (Only available if APIC enabled)
101 IRQ21 (Only available if APIC enabled)
110 IRQ22 (Only available if APIC enabled)
111 IRQ23 (Only available if APIC enabled)
NOTE: When the TCO interrupt is mapped to APIC interrupts 9, 10 or 11, the signal is in fact active
high. When the TCO interrupt is mapped to IRQ 20, 21, 22, or 23, the signal is active low and
can be shared with PCI interrupts that may be mapped to those same signals (IRQs).
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Intel^® 82801CA ICH3-S Datasheet