SC2200 datasheet(167/433 Pages) NSC

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Core Logic Module (Continued)

5.2.9

Power Management Logic

The Core Logic module integrates advanced power man-

agement features including idle timers for common system

peripherals, address trap registers for programmable

address ranges for I/O or memory accesses, four program-

mable general purpose external inputs, clock throttling with

automatic speedup for the GX1 clock, software GX1 stop

clock, 0V Suspend/Resume with peripheral shadow regis-

ters, and a dedicated serial bus to/from the GX1 module

providing power management status.

The Core Logic module is ACPI (Advanced Configuration

Power Interface) compliant. An ACPI-compliant system is

one whose underlying BIOS, device drivers, chipset and

peripherals conform to revision 1.0 of the ACPI specifica-

tion. The Core Logic also supports Advanced Power Man-

agement (APM).

The SC2200 provides the following support of ACPI states:

• CPU States: C0, C1, and C3.

• Sleep States:

— SL1/SL2 - ACPI S1 equivalent.

— SL3 - ACPI S3 equivalent.

— SL4 - ACPI S4 equivalent.

— SL5 - ACPI S5 equivalent.

• General Purpose Events: Fully programmable GPE0

Event Block registers.

• Wakeup Events: Supported through GPWIO[2:0] which

are powered by standby voltage and generate SMIs.

See registers at F1BAR1+I/O Offset 0Ah and

F1BAR1+I/O Offset 12h. Also see Section 4.6 "System

Wakeup Control (SWC)" on page 125 and Table 5-5

"Wakeup Events Capability" on page 168.

SC2200 device power management is highly tuned for low

power systems. It allows the system designer to implement

a wide range of power saving modes using a wide range of

capabilities and configuration options.

SC2200 controls the following functions directly:

• The system clocks.

• Core processor power states.

• Wakeup/resume event detection, including general

purpose events.

• Power supply and power planes.

It also supports systems with an external micro controller

that is used as a power management controller.

5.2.9.1

CPU States

The SC2200 supports three CPU states: C0, C1 and C3

(the Core Logic C2 CPU state is not supported). These

states are fully compliant with the ACPI specification, revi-

sion 1.0. These states occur in the Working state only

(S0/G0). They have no meaning when the system transi-

tions into a Sleep state. For details on the various Sleep

states, see Section 5.2.9.2 "Sleep States" on page 167.

C0 Power State - On

In this state the GX1 module executes code. This state has

two sub-states: Full Speed or Throttling; selected via the

THT_EN bit (F1BAR1+I/O Offset 00h[4]).

C1 Power State - Active Idle

The SC2200 enters the C1 state, when the Halt Instruction

(HLT) is executed. It exits this state back to the C0 state

upon an NMI, an unmasked interrupt, or an SMI. The Halt

instruction stops program execution and generates a spe-

cial Halt bus cycle. (See “Usage Hints” on page 170.)

Bus masters are supported in the C1 state and the SC2200

will temporarily exit C1 to perform a bus master transaction.

C2 Power State

The SC2200 does not support the C2 power state. All rele-

vant registers and bit fields in the Core Logic are reserved.

C3 Power State

The SC2200 enters the C3 state, when the P_LVL3 register

(F1BAR1+I/O Offset 05h) is read. It exits this state back to

the C0 state (Full Speed or Throttling, depending on the

THT_EN bit) upon:

• An NMI, an unmasked interrupt, or an SMI.

• A bus master request, if enabled via the BM_RLD bit

(F1BAR1+I/O Offset 0Ch[1]).

In this state, the GX1 module is in Suspend Refresh mode

(for details, see the Power Management section of the

GX1

Processor Series Datasheet, and Section 5.2.9.5 "Usage

Hints" on page 170).

PCI arbitration should be disabled prior entering the C3

state via the ARB_DIS bit in the PM2_CNT register

(F1BAR1+I/O Offset 20h[0]) because a PCI arbitration

event could start after P_LVL3 has been read. After

wakeup ARB_DIS needs to be cleared.

5.2.9.2

Sleep States

The SC2200 supports four Sleep states (SL1-SL3) and the

Soft Off state (G2/S5). These states are fully compliant

with the ACPI specification, revision 1.0.

When the SLP_EN bit (F1BAR1+I/O Offset 0Ch[13]) is set

to 1, the SC2200 enters an SLx state according to the

SLP_TYPx field (F1BAR1+I/O Offset 0Ch[12:10]). It exits

the Sleep state back to the S0 state (C0 state - Full Speed

or Throttling, depending on the THT_EN bit) upon an

enabled power management event. Table 5-5 on page 168

lists wakeup events from the various Sleep states.

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