Functional Description
274 Datasheet
10.4 Thermal Sensor
There are several registers that need to be configured to support the MCH thermal
sensor functionality and SMI# generation. Customers must enable the Catastrophic
Trip Point as protection for the MCH. If the Catastrophic Trip Point is crossed, then the
MCH will instantly turn off all clocks inside the device. Customers may optionally enable
the Hot Trip Point to generate SMI #. Customers will be required to then write their own
SMI# handler in BIOS that will speed up the MCH (or system) fan to cool the part.
10.4.1 PCI Device 0, Function 0
The SMICMD register requires that a bit be set to generate an SMI# when the Hot Trip
point is crossed. The ERRSTS register can be inspected for the SMI alert.
10.4.2 MCHBAR Thermal Sensor Registers
The Digital Thermometer Configuration Registers reside in the MCHBAR configuration
space.
Register Name
Register
Symbol
Register
Start
Register
End
Default
Value
Access
Error Status ERRSTS C8 C9 0000h RWC/S, RO
SMI Command SMICMD CC CD 0000h RO, RW
Register Name
Register
Symbol
Register
Start
Register
End
Default
Value
Access
Thermal Sensor Control 1 TSC1 CD8 CD8 00h
RW/L, RW,
RS/WC
Thermal Sensor Control 2 TSC2 CD9 CD9 00h RO, RW/L
Thermal Sensor Status TSS CDA CDA 00h RO
Thermal Sensor Temperature Trip
Point
TSTTP CDC CDF 00000000h RO, RW, RW/L
Thermal Calibration Offset TCO CE2 CE2 00h RW/L/K, RW/L
Hardware Throttle Control THERM1 CE4 CE4 00h
RW/L, RO,
RW/L/K
TCO Fuses THERM3 CE6 CE6 00h RO, RS/WC
Thermal Interrupt Status TIS CEA CEB 0000h RO, RWC
Thermal SMI Command TSMICMD CF1 CF1 00h RO, RW
