
SiS5595 PCI System I/O Chipset
Preliminary V2.0 Nov. 2, 1998 15 Silicon Integrated Systems Corporation
SERIAL IRQ SAMPLING PERIODS
IRQ/Data Frame
14
15
16
17
18
19
20
21
32:22
Signal Sampled
IRQ13
IRQ14
IRQ15
IOCHCK#
INTA#
INTB#
INTC#
INTD#
Unassigned
# of clocks past Start
41
44
47
50
53
56
59
62
95
At the end of each Sample phase, the SiS5595 will sample the state of the SIRQ# line and
replicate the status on the original IRQ/Data line at the input to the 8259s Interrupt
Controller.
3.1.4.4 Stop Cycle Control
Once all IRQ/Data frames have completed, the SiS5595 will terminate SIRQ# activity by
driving Stop cycle. Only the SiS5595 can initiate the stop frame. A Stop Frame is indicated
by the SiS5595 driving SIRQ# low for two clocks (Quiet Mode) or 3 clocks (Continuous
Mode), then back high for one clock. In the Quiet mode, any serial IRQ device may initiate a
Start frame in the third clock or more after the rising edge of the Stop frame pulse. In the
Continuous mode, only the SiS5595 may initiate a Start frame in the third clock or more after
the rising edge of the Stop frame pulse.
3.2
ACPI /LEGACY PMU
3.2.1 ADVANCED CONFIGURATION AND POWER INTERFACE (ACPI)
Advanced Configuration and Power Interface (ACPI) is PC 97/98 specification. ACPI extends
the portability for different platforms by moving the power management function into the OS.
ACPI also releases the restriction of ROM BIOS capacity on the complexity of the advanced
power management functions. The power management events of ACPI are initiated by the
assertion of System Control Interrupt (SCI). System uses SCI to send ACPI-relevant
notifications to the host OS, and then OS executes the specific service sub-routines
according to which enable bit and status bit is set.
The ACPI architecture in SiS5595 consists of the Fixed Features logic, Generic Features
logic, Legacy Features logic, and the configuration registers to ensure fluent communication
with the ACPI-compliant OS. The Fixed Features meet ACPI SPEC 1.0 requirement. The
SCI/SMI# generating logic in ACPI senses external environmental changes or requests and
interrupts, the OS to take some action. The wakeup logic will sequence the system from the
S1/S2 to G0/S0 working state. Besides, sequencing the system from S3/S5 to G0/S0 can
only be achieved through the power up events processed in the RTC/APC module.
3.2.1.1 Fixed Features