CS5530A datasheet(78/259 Pages) NSC

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Functional Description (Continued)

3.4.3.5

Power Management SMI Status Reporting

Registers

The CS5530A 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 processor

through the SMI# pin. It is active low. When an SMI is initi-

ated, the SMI# pin is asserted low and is held low until all

SMI sources are cleared. At that time, SMI# is deasserted.

All SMI sources report to the Top Level SMI Status Regis-

ter (F1BAR+Memory Offset 02h) and the Top Level SMI

Status Mirror Register (F1BAR+Memory Offset 00h). The

Top SMI Status 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 F1BAR+Memory Offset 02h

clears the status.

Since all SMI sources report to the Top Level SMI Status

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.

Enable GPIO3 as an External SMI Source: Allow GPIO3 to be an external SMI source and to generate an SMI on either a

rising or falling edge transition (depends upon setting of bit 4) 0 = Disable; 1 = Enable.

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status reporting is at F0 Index 84h/F4h[0].

Note: For any of the above bits to function properly, the respective GPIO pin must be configured as an input (F0 Index 90h).

Table 3-32. GPIO Pin Configuration/Control Registers (Continued)

Bit

Description

CS5530A Datasheet(PDF) 78 Page - National Semiconductor (TI)