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2 acpi support registers, Table 6-34, F1bar1+i/o offset: acpi support registers – AMD Geode SC1201 User Manual

Page 247: Table 6-34)

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AMD Geode™ SC1200/SC1201 Processor Data Book

247

Core Logic Module - SMI Status and ACPI Registers - Function 1

32579B

6.4.2.2

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 6-34 shows the I/O mapped ACPI Sup-
port registers accessed through F1BAR1.

Table 6-34. 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.

4

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).

0:

Disable.

1:

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].

3

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

7:6

LED_CNT (LED Output Control). Controls the blinking of an LED when in the SL4 or SL5 sleep state

00: Disable (LED# signal, is HiZ).

01: Zero (LED# signal is HiZ).

10: Blink @ 1 Hz rate, when in SL4 and SL5 sleep states. Duty cycle: LED# is 10% pulled low, 90% HiZ.

11: One (LED# is pulled low, when in SL4 and SL5 sleep states)

5

Reserved. Must be set to 0.

4

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.

3

GPWIO_DBNC_DIS (GPWIO0 and GPWIO1 Debounce). When enabled, a high-to-low or low-to-high transition of greater
than 15.8 ms is required for GPWIO0 and GPWIO1 to be recognized.

0: Enable. (Default)

1: Disable. (No debounce)

GPWIO2 pin does not have debounce capability.

2:1

Reserved. Must be set to 0.

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