Field Name Bits Default HCD HC Description
DR 15:0 0000h RW R
DeviceRemovable
Each bit is dedicated to a port of the Root Hub. When
cleared, the attached device is removable. When set,
the attached device is not removable.
bit 0: Reserved
bit 1: Device attached to Port #1
bit 2: Device attached to Port #2
...
bit15: Device attached to Port #15
PPCM 31:16 0000h RW R
PortPowerControlMask
Each bit indicates if a port is affected by a global
power control command when
PowerSwitchingMode is set. When set, the port's
power state is only affected by per-port power control
(Set/ClearPortPower). When cleared, the port is
controlled by the global power switch
(Set/ClearGlobalPower). If the device is configured
to global switching mode
(PowerSwitchingMode=0), this field is not valid.
bit 0: Reserved
bit 1: Ganged-power mask on Port #1
bit 2: Ganged-power mask on Port #2
...
bit15: Ganged-power mask on Port #15
HcRhStatus - 32 bits - [MEM_Reg : 50h] Field Name Bits Default HCD HC Description
LPS 0 0b RW R
(Read) LocalPowerStatus
The Root Hub does not support the local power
status feature; thus, this bit is always read as ‘0’.
(Write) ClearGlobalPower
In global power mode (PowerSwitchingMode=0),
This bit is written to ‘1’ to turn off power to all ports
(Clear)
PortPowerStatus). In per-port power mode, it clears
PortPowerStatus only on ports whose
PortPowerControlMask bit is not set. Writing a ‘0’
has no effect.
OCI 1 0b R RW
OverCurrentIndicator
This bit reports overcurrent conditions when the
global reporting is implemented. When set, an
overcurrent condition exists. When cleared, all power
operations are normal. If per-port overcurrent
protection is implemented this bit is always ‘0’
Reserved 14:2 Reserved
DRWE 15 0b RW R
(Read) DeviceRemoteWakeupEnable
This bit enables a ConnectStatusChange bit as a
resume event, causing a USBSUSPEND to
USBRESUME state transition and setting the
ResumeDetected interrupt.
0 = ConnectStatusChange is not a remote wakeup
event.
1 = ConnectStatusChange is a remote wakeup
event.
(Write) SetRemoteWakeupEnable
Writing a '1' sets DeviceRemoveWakeupEnable.
Writing a '0' has no effect.