AMD SC2200 manual Power Button Override, Thermal Monitoring

Core Logic Module 32580B

Power Button

The power button (PWRBTN#) input provides two events: a wake request, and a sleep request. For both these events, the PWRBTN# signal is debounced (i.e., the signal state is transferred only after 14 to 16 ms without transitions, to ensure that the signal is no longer bouncing).

ACPI is non-functional and all ACPI outputs are undefined when the power-up sequence does not include using the power button. SUSP# is an internal signal generated from the ACPI block. Without an ACPI reset, SUSP# can be per- manently asserted. If the USE_SUSP bit in CCR2 of GX1 module is enabled (Index C2h[7] = 1), the CPU will stop.

If ACPI functionality is desired, or the situation described above avoided, the power button must be toggled. This can be done externally or internally. GPIO63 is internally con- nected to PWRBTN#. To toggle the power button with soft- ware, GPIO63 must be programmed as an output using the normal GPIO programming protocol (see Section 6.4.1.1 "GPIO Support Registers" on page 233). GPIO63 must be pulsed low for at least 16 ms and not more than 4 sec.

Asserting POR# has no effect on ACPI. If POR# is asserted and ACPI was active prior to POR#, then ACPI will remain active after POR#. Therefore, BIOS must ensure that ACPI is inactive before GPIO63 is pulsed low.

Power Button Wake Event - Detection of a high-to-low transition on the debounced PWRBTN# input signal when in SL1 to SL5 Sleep states. The system is considered in the Sleep state, only after it actually transitioned into the state and not only according to the SLP_TYP field.

In reaction to this event, the PWRBTN_STS bit (F1BAR1+I/O Offset 08h[8]) is set to 1 and a wakeup event or an interrupt is generated (note that this is regardless of the PWRBTN_EN bit, F1BAR1+I/O Offset 0Ah[8]).

Power Button Sleep Event - Detection of a high-to-low transition on the debounced PWRBTN# input signal, when in the Working state (S0).

In reaction to this event, the PWRBTN_STS bit is set to 1.

•When both the PWRBTN_STS bit and the

PWRBTN_EN bit are set to 1, an SCI interrupt is gener- ated.

•When SCI_EN bit is 0, ONCTL# and PWRCNT[2:1] are de-asserted immediately regardless of the PWRBTN_EN bit.

Power Button Override

When PWRBTN# is 0 for more than four seconds, ONCTL# and PWRCNT[2:1] are de-asserted (i.e., the system transi- tions to the SL5 state, “Soft Off”). This power management event is called the power button override event.

In reaction to this event, the PWRBTN_STS bit is cleared to 0 and the PWRBTNOR_STS bit (F1BAR1+I/O Offset 08h[11]) is set to 1.

Thermal Monitoring

The thermal monitoring event (THRM#) enables control of ACPI-OS Control.

When the THRM# signal transitions from high-to-low, the THRM_STS bit (F1BAR1+I/O Offset 10h[5]) is set to 1. If the THRM_EN bit (F1BAR1+I/O Offset 12h[5]) is also set to 1, an interrupt is generated.

SDATA_IN2, IRRX1, RI2#

Section 5.4.1 "SIO Control and Configuration Registers" on page 103 for control and operation.

6.2.9.5Usage Hints

•During initialization, the BIOS should:

—Clear the SUSP_HLT bit in CCR2 (GX1 module, Index C2h[3]) to 0. This is needed for compliance with C0 definition of ACPI, when the Halt Instruction (HLT) is executed.

—Disable the SUSP_3V option in C3 power state (F0 Index 60h[2]).

—Disable the SUSP_3V option in SL1 sleep state (F0 Index 60h[1]).

•SMM code should clear the CLK_STP bit in the PM Clock Stop Control register (GX_BASE+Memory Offset 8500h[0]) to 0 when entering C3 state.

•SMM code should correctly set the CLK_STP bit in the PM Clock Stop Control register (GX_BASE+Memory Offset 8500h[0]) when entering the SL1, SL2, and SL3 states.

AMD Geode™ SC2200 Processor Data Book 169