AMD SC1201, SC1200 manual Power Management SMI Status Reporting Registers, Module, F1BAR0+I/O

Core Logic Module 32579B

Power Management SMI Status Reporting Registers

The Core Logic module updates status registers to reflect the SMI sources. Power management SMI sources are the device idle timers, address traps, and general purpose I/O pins.

Power management events are reported to the GX1 mod- ule through the active low SMI# signal. When an SMI is ini- tiated, the SMI# signal is asserted low and is held low until all SMI sources are cleared. At that time, SMI# is de- asserted.

All SMI sources report to the Top Level SMI Status register (F1BAR0+I/O Offset 02h) and the Top Level SMI Status Mirror register (F1BAR0+I/O Offset 00h). The Top SMI Sta- tus and Status Mirror registers are the top level of hierarchy for the SMI Handler in determining the source of an SMI.

These two registers are identical except that reading the register at F1BAR0+I/O Offset 02h clears the status.

Since all SMI sources report to the Top Level SMI Status register, many of its bits combine a large number of events requiring a second level of SMI status reporting. The sec- ond level of SMI status reporting is set up very much like the top level. There are two status reporting registers, one “read only” (mirror) and one “read to clear”. The data returned by reading either offset is the same, the difference between the two being that the SMI can not be cleared by reading the mirror register.

Figure 6-11shows an example SMI tree for checking and clearing the source of General Purpose Timers and the User Defined Trap generated SMI.

SMI# Asserted

SMM software reads SMI Header

If Bit X = 1

If Bit X = 0

GX1

(External SMI)

(Internal SMI)

Call internal SMI handler

Module

to take appropriate action

Core Logic

Module

F1BAR0+I/O

Offset 02h

SMI de-asserted after all SMI Sources are Cleared

Read to Clear

(i.e., Top and Second Levels - note some sources may have a Third Level)

to determine

top-level source

of SMI

F1BAR0+I/O

Offset 06h

Read to Clear

to determine

Bits [15:10]

second-level

source of SMI

Other_SMI

If bit 9 = 1,

Bits [15:6]

Source of SMI

RSVD

Bit 9

is GP Timer or UDEF Trap

GTMR_TRP_SMI

Bit 5

PCI_TRP_SMI

Bit 4

UDEF3_TRP_SMI

Bit 3

Take

UDEF2_TRP_SMI

Bits [8:0]

Appropriate

Bit 2

Other_SMI

Action

UDEF1_TRP_SMI

Bit 1

GPT2_SMI

Bit 0

GPT1_SMI

Top Level

Second Level

Figure 6-11. General Purpose Timer and UDEF Trap SMI Tree Example

AMD Geode™ SC1200/SC1201 Processor Data Book 165