SC2200 NSC [National Semiconductor], SC2200 Datasheet - Page 221

• Manufacturer Part Number: SC2200
• Description: Thin Client On a Chip
• Manufacturer: NSC [National Semiconductor]

Revision 3.0
Core Logic Module
Table 5-29. F0: PCI Header and Bridge Configuration Registers for GPIO and LPC Support (Continued)
Index 94h-95h
Index 96h
Index 97h
Index 98h-99h
Index 9Ah-9Bh
15:8
15:0
15:0
7:0
7:3
Bit
2
1
0
Description
Suspend Signal Asserted Counter. This 8-bit counter represents the number of 32 µs intervals that the internal SUSP#
signal is asserted to the GX1 module. Together with bits [7:0], perform the Suspend Modulation function for CPU power
management. The ratio of SUSP# asserted-to-deasserted sets up an effective (emulated) clock frequency, allowing the
power manager to reduce GX1 module power consumption.
This counter is prematurely reset if an enabled speedup event occurs (i.e., IRQ and video speedups).
Suspend Signal Deasserted Counter. This 8-bit counter represents the number of 32 µs intervals that the internal SUSP#
signal is deasserted to the GX1 module. Together with bits [15:8], perform the Suspend Modulation function for CPU power
management. The ratio of SUSP# asserted-to-deasserted sets up an effective (emulated) clock frequency, allowing the
power manager to reduce GX1 module power consumption.
This counter is prematurely reset if an enabled speedup event occurs (i.e., IRQ and video speedups).
Reserved. Must be set to 0.
Suspend Mode Configuration. Special 3V Suspend mode to support powering down the GX1 module during Suspend.
0: Disable.
1: Enable.
SMI Speedup Configuration. Selects how the Suspend Modulation function should react when an SMI occurs.
0: Use the IRQ Speedup Timer Count Register (F0 Index 8Ch) to temporarily disable Suspend Modulation when an SMI
1: Disable Suspend Modulation when an SMI occurs until a read to the SMI Speedup Disable Register (F1BAR0+I/O Offset
The purpose of this bit is to disable Suspend Modulation while the GX1 module is in the System Management Mode so that
VSA and Power Management operations occur at full speed. Two methods for accomplishing this are:
Map the SMI into the IRQ Speedup Timer Count Register (F0 Index 8Ch).
- or -
Have the SMI disable Suspend Modulation until the SMI handler reads the SMI Speedup Disable Register (F1BAR0+I/O
Offset 08h). This the preferred method.
This bit has no affect if the Suspend Modulation feature is disabled (bit 0 = 0).
Suspend Modulation Feature Enable. This bit is used to enable/disable the Suspend Modulation feature.
0: Disable.
1: Enable.
When enabled, the internal SUSP# signal is asserted and deasserted for the durations programmed in the Suspend Modu-
lation register (F0 Index 94h).
The setting of this bit is mirrored in the Top Level PME/SMI Status register (F1BAR0+I/O Offset 00h/02h[15]. It is used by
the SMI handler to determine if the SMI Speedup Disable register (F1BAR0+I/O Offset 08h) must be cleared on exit.
Primary Hard Disk Idle Timer Count. This idle timer is used to determine when the primary hard disk is not in use so that
it can be powered down. The 16-bit value programmed here represents the period of hard disk inactivity after which the sys-
tem is alerted via an SMI. The timer is automatically reloaded with the count value whenever an access occurs to the config-
ured hard disk’s data port (I/O port 1F0h or 3F6h).
This counter uses a 1 second timebase. To enable this timer, set F0 Index 81h[0] = 1.
Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[0].
Second level SMI status is reported at F0 Index 85h/F5h[0].
Floppy Disk Idle Timer Count. This idle timer is used to determine when the floppy disk drive is not in use so that it can be
powered down. The 16-bit value programmed here represents the period of floppy disk drive inactivity after which the sys-
tem is alerted via an SMI. The timer is automatically reloaded with the count value whenever an access occurs to the config-
ured floppy drive’s data port (I/O port 3F5h or 375h).
This counter uses a 1 second time base. To enable this timer, set F0 Index 81h[1] = 1.
Top level SMI status is reported at F1BAR0+I/O Offset 00h/02h[0].
Second level SMI status is reported at F0 Index 85h/F5h[1].
occurs.
08h).
Primary Hard Disk Idle Timer Count Register (Primary Channel) (R/W)
(Continued)
Floppy Disk Idle Timer Count Register (R/W)
Suspend Configuration Register (R/W)
Suspend Modulation Register (R/W)
Reserved
221
Reset Value: 0000h
Reset Value: 0000h
Reset Value: 0000h
Reset Value: 00h
Reset Value: 00h
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