Field Name Bits Default Description
SwitchVoltageTime 5:0 05h Programmable value (in 2us increment with 2us uncertainty)
Reserved 7:6 00b
SwitchVoltageTime register
SwitchGHI_Time - RW – 8 bits - [PM_Reg: 64h] Field Name Bits Default Description
SwitchGhiTime 5:0 02h Programmable value (in 2us increment with 2us uncertainty)
Reserved 7:6 00b
SwitchGHITime register
UsbPMControl- RW – 8 bits - [PM_Reg: 65h] Field Name Bits Default Description
UsbPhyS5PwrDwnEnable 0 0b Set to 1 to enable S4/S5 USB Phy power down support and to
disable S4 USB wakeup support.
The bit has to be clear to 0 (default) to support S4 USB
wakeup.
Reserved 1 0b
UsbResumeEnable 2 1b Set to 1 to enable S3 wakeup on USB device resume
Reserved 3 0b
UsbResetByPciRstEnable 4 1b Set to 1 to reset USB on the software (such as IO-64 or IO-
CF9 cycles) generated PCIRST#.
UsbS5ResetEnable 5 1b Set to 1 to enable USB reset on S4/S5 resume detection
Reserved 6 0b
SpecialFunc 7 0b If set to 1, S* -> S0 state transitions will use 1ms clock for
timing sequence; otherwise, 8µs clock will be used.
For K8 system, this bit must be cleared to use 8µs clock.
UsbPMControl register
MiscEnable66 - RW – 8 bits - [PM_Reg: 66h] Field Name Bits Default Description
UsbBusyBreakEn
(available after A13) 0 0b
Setting this bit to 1 will cause C3/4 wakeup when USB OHCI
or EHCI DMA is active.
UsbOhciCstateMask
(available after A13) 1 0b
Setting this bit to 1 will prevent the system from entering C
state when USB OHCI DMA is active.
Reserved 4:2 000b
K8KbRstEn
5 0b
KB_RST# control for K8 system
0: Generate INIT#
1: Generate PCIRST#
UsbBusyBmStsEn 6 0b Setting this bit to 1 will cause C3/4 pop-up when USB OHCI or
EHCI DMA is active.
UsbOhciBmStsRdEn
(available after A13) 7 0b
Setting this bit to 1 will keep BM_STS read as 1 regardless of
BmStsRdMask when USB OHCI DMA is active.
MiscEnable66 register
MiscEnable67 – RW – 8 bits – [PM_Reg:67h] Field Name Bits Default Description
CPU_STP_En 0 0b
CPU_STP# enable for C3 state in P4 system; no effect in K8
systems, for which CPU_STP# is always deasserted.
Slp_En 1 0b SLP# enable in C states
CC_En 2 0b C State enable; must be set in order to exercise C state
Reserved 3
BypassPwrGoodEn 4 0b If asserted, Southbridge will not wait for deassertion of
PWRGOOD to monitor for wakeup event