Intel Extensible Firmware Interface - Manual (Page 567)

Protocols — USB Support
Version 1.10 12/01/02 14-27
//**************************************************
// EFI_USB_PORT_STATUS.PortChangeStatus bit definition
//**************************************************
#define USB_PORT_STAT_C_CONNECTION 0x0001
#define USB_PORT_STAT_C_ENABLE 0x0002
#define USB_PORT_STAT_C_SUSPEND 0x0004
#define USB_PORT_STAT_C_OVERCURRENT 0x0008
#define USB_PORT_STAT_C_RESET 0x0010
PortStatus Contains current port status bitmap. The root hub port status
bitmap is unified with the USB hub port status bitmap. See
Table 14-1 for a reference, which is borrowed from Chapter 11,
Hub Specification, of USB Specification, Revision 1.1.
PortChangeStatus Contains current port status change bitmap. The root hub port
change status bitmap is unified with the USB hub port status
bitmap. See Table 14-2 for a reference, which is borrowed from
Chapter 11, Hub Specification, of USB Specification, Revision 1.1.
Table 14-1. USB Hub Port Status Bitmap
Bit Description
0 Current Connect Status: (USB_PORT_STAT_CONNECTION) This field reflects whether or not a
device is currently connected to this port.
0 = No device is present
1 = A device is present on this port
1 Port Enable / Disabled: (USB_PORT_STAT_ENABLE) Ports can be enabled by software only.
Ports can be disabled by either a fault condition (disconnect event or other fault condition) or by
software.
0 = Port is disabled
1 = Port is enabled
2 Suspend: (USB_PORT_STAT_SUSPEND) This field indicates whether or not the device on this
port is suspended.
0 = Not suspended
1 = Suspended
3 Over-current Indicator: (USB_PORT_STAT_OVERCURRENT) This field is used to indicate that
the current drain on the port exceeds the specified maximum.
0 = All no over-current condition exists on this port
1 = An over-current condition exists on this port
4 Reset: (USB_PORT_STAT_RESET) Indicates whether port is in reset state.
0 = Port is not in reset state
1 = Port is in reset state
continued