82801BA Datasheet, PDF (269/498 Pages) Intel Corporation – Intel 82801BA I/O Controller Hub 2 (ICH2) and Intel 82801BAM I/O Controller Hub 2 Mobile

LPC Interface Bridge Registers (D31:F0)
9.1.12
9.1.13
BIOS_CNTL (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
4E–4Fh
0000h
No
Attribute:
Size:
Power Well:
R/W
16-bit
Core
Bit
Description
15:2 Reserved.
BIOS Lock Enable (BLE)—R/W.
1 = Enables setting the BIOSWE bit to cause SMIs.
1
0 = Setting the BIOSWE will not cause SMIs. Once set, this bit can only be cleared by a
PCIRST#.
BIOS Write Enable (BIOSWE)—R/W.
1 = Access to the BIOS space is enabled for both read and write cycles. When this bit is written
0
from a 0 to a 1 and BIOS lock Enable (BLE) is also set, an SMI# is generated. This ensures
that only SMM code can update BIOS.
0 = Only read cycles result in FWH interface cycles.
TCO_CNTL—TCO Control (LPC I/F—D31:F0)
Offset Address: 54h
Default Value: 00h
Lockable:
No
Attribute:
Size:
Power Well:
R/W
8-bit
Core
Bit
Description
7:4 Reserved.
TCO Interrupt Enable (TCO_INT_EN)—R/W. This bit enables/disables the TCO interrupt.
3
1 = Enables TCO Interrupt, as selected by the TCO_INT_SEL field.
0 = Disables TCO interrupt.
TCO Interrupt Select (TCO_INT_SEL)—R/W. Specifies which IRQ the TCO internally appears. If
not using the APIC, the TCO interrupt must be routed to IRQ[9:11], and that interrupt is not
sharable with the SERIRQ stream, but is shareable with other PCI interrupts. If using the APIC, the
TCO interrupt can also be mapped to IRQ[20:23], and can be shared with other interrupt. Note that
if the TCOSCI_EN bit is set (bit 6 in the GPE0_EN register), then the TCO interrupt will be sent to
the same interrupt as the SCI, and the TCO_INT_SEL bits will have no meaning. When the TCO
interrupt is mapped to APIC interrupts 10 or 11, the signal is, in fact, active high. When the TCO
interrupt is mapped to IRQ[20, 21, or 22], the signal is active low and can be shared with PCI
interrupts that may be mapped to the same signals (IRQs).
2:0 000 = IRQ9
001 = IRQ10
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)
82801BA ICH2 and 82801BAM ICH2-M Datasheet
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