Revision 3.0
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G
Core Logic Module
(Continued)
9
NoPowerSwitching.
This bit should be written to support the external system port power switching implementation.
0: Ports are power switched.
1: Ports are always powered on.
8
PowerSwitchingMode.
This bit is only valid when NoPowerSwitching is cleared. This bit should be written 0.
0: Global Switching.
1: Individual Switching
7:0
NumberDownstreamPorts (Read Only).
USB supports three downstream ports.
Note:
This register is only reset by a power-on reset (PCIRST#). It is written during system initialization to configure the Root Hub.
These bit should not be written during normal operation.
Offset 4Ch-4Fh
HcRhDescriptorB Register (R/W)
Reset Value = 00000000h
31:16
PortPowerControlMask.
Global-power switching. This field is only valid if NoPowerSwitching is cleared and Power-
SwitchingMode is set (individual port switching). When set, the port only responds to individual port power switching com-
mands (Set/ClearPortPower). When cleared, the port only responds to global power switching commands
(Set/ClearGlobalPower).
0: Device not removable.
1: Global-power mask.
Port Bit relationship - Unimplemented ports are reserved, read/write 0.
0 = Reserved
1 = Port 1
2 = Port 2
...
15 = Port 15
15:0
DeviceRemoveable.
USB ports default to removable devices.
0: Device not removable.
1: Device removable.
Port Bit relationship
0 = Reserved
1 = Port 1
2 = Port 2
...
15 = Port 15
Unimplemented ports are reserved, read/write 0.
Note:
This register is only reset by a power-on reset (PCIRST#). It is written during system initialization to configure the Root Hub.
These bit should not be written during normal operation.
Offset 50h-53h
HcRhStatus Register (R/W)
Reset Value = 00000000h
31
ClearRemoteWakeupEnable (Write Only).
Writing a 1 to this bit clears DeviceRemoteWakeupEnable. Writing a 0 has no
effect.
30:18
Reserved.
Read/Write 0s.
17
OverCurrentIndicatorChange.
This bit is set when OverCurrentIndicator changes. Writing a 1 clears this bit. Writing a 0
has no effect.
16
Read: LocalPowerStatusChange.
Not supported. Always read 0.
Write: SetGlobalPower.
Write a 1 issues a SetGlobalPower command to the ports. Writing a 0 has no effect.
15
Read: DeviceRemoteWakeupEnable.
This bit enables ports' ConnectStatusChange as a remote wakeup event.
0: Disabled.
1: Enabled.
Write: SetRemoteWakeupEnable.
Writing a 1 sets DeviceRemoteWakeupEnable. Writing a 0 has no effect.
14:2
Reserved.
Read/Write 0s.
Table 5-42. USB_BAR+Memory Offset: USB Controller Registers (Continued)
Bit
Description