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Revision 1.1

Core Logic Module (Continued)

5.4.2.2

ACPI Support Registers

F1 Index 40h, Base Address Register 1 (F1BAR1), points

to the base address of where the ACPI Support registers

are located. Table 5-34 shows the I/O mapped ACPI Sup-

port registers accessed through F1BAR1.

Table 5-34. F1BAR1+I/O Offset: ACPI Support Registers

Bit

Description

Offset 00h-03h

P_CNT — Processor Control Register (R/W)

Reset Value: 00000000h

31:5

Reserved. Always reads 0.

THT_EN (Throttle Enable). When this bit is asserted, it enables throttling of the clock based on the CLK_VAL field (bits

[2:0] of this register).

Disable.

Enable.

If F1BAR1+I/O Offset 18h[8] =1, an SMI is generated when this bit is set.

Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[2].

Second level SMI status is reported at F1BAR0+I/O Offset 20h/22h[1].

Reserved. Always reads 0.

2:0

CLK_VAL (Clock Throttling Value). CPU duty cycle:

000: Reserved

010: 25%

100: 50%

110: 75%

001: 12.5%

011: 37.5%

101: 62.5%

111: 87.5%

Offset 04h

Reserved

Reset Value: 00h

Note:

This register should not be read. It controls a reserved function of power management logic.

Offset 05h

P_LVL3 — Enter C3 Power State Register (RO)

Reset Value: xxh

7:0

P_LVL3 (Power Level 3). Reading this 8-bit read only register causes the processor to enter the C3 power state. Reads of

P_LVL3 return 0. Writes have no effect.

The ACPI state machine always waits for an SMI (any SMI) to be generated and serviced before transfer into C3 power

state.

A read of this register causes an SMI if enabled: F1BAR1+I/O Offset 18h[11] = 1. (Default)

Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[2].

Second level SMI status is reported at F1BAR0+I/O Offset 20h/22h[4].

Offset 06h

SMI_CMD — OS/BIOS Requests Register (R/W)

Reset Value: 00h

7:0

SMI_CMD (SMI Command and OS / BIOS Requests). A write to this register stores data and a read returns the last data

written. In addition, a write to this register always generates an SMI. A read of this register does not generate an SMI.

Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[2].

Second level SMI status is reported at F1BAR0+I/O Offset 20h/22h[0].

Offset 07h

ACPI_FUN_CNT — ACPI Function Control Register (R/W)

Reset Value: 00h

7:5

Reserved. Must be set to 0.

INTR_WU_SL1. Enables wakeup on enabled interrupts in sleep state SL1.

0: Disable wakeup from SL1, when an enabled interrupt is active.

1: Enable wakeup from SL1, when an enabled interrupt is active.

GPWIO_DBNC_DIS (GPWIO0 and GPWIO1 Debouncers). Debounce settings for GPWIO0 (ball AC15) and GPWIO1 (ball

AE16). Selects the time that a high-to-low or low-to-high transition (debounce period) must be for GPWIO0 to be recog-

nized.

0: Debounce period is 15.8 msec. (Default)

1: Debounce period is 31 µs.

GPWIO2 is fixed at 31 µs.

2:1

Reserved. Must be set to 0.

PWRBTN_DBNC_DIS (Power Button Debouncer). Allow a high-to-low or low-to-high transition of greater than 15.8 msec

(debounce period) on PWRBTN# (ball AF15) before it is recognized.

0: Enable. (Default)

1: Disable.

SC1100 Datasheet(PDF) 216 Page - National Semiconductor (TI)

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