IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 355 / 744

IDT Register Organization
PES32NT24xG2 User Manual 19 - 11 January 30, 2013
Proprietary Port-Specific Registers in the PCI-to-PCI Bridge Function
This section outlines the address range 0x400 through 0xFFF in the configuration space of the PCI-to-PCI bridge function. This address range
contains IDT proprietary registers that are port-specific (i.e., provide control or status on a per-port basis). These registers control proprietary function-
ality or provide status beyond the functionality outlined in the PCI Express Base Specification. In some cases, the proprietary functionality is associ-
ated with a specific port function (e.g., PCI-to-PCI bridge function), and in other cases with the operation of the port (i.e., affecting all it’s functions).
Proprietary port-specific registers always affect the operation of the port and always reflect status associated with the port, regardless of the port’s
operating mode. For port operating modes in which the PCI-to-PCI bridge function is not present in the port, the proprietary port registers are only
accessible via the switch’s global address space. In such operating modes, the proprietary port registers continue to have effect on the operation of
the port.
Registers in this address range may be accessed using PCI Express configuration requests to the corresponding PCI-to-PCI bridge function (if
present in the port), through the global address space access registers, via the SMBus slave interface, or via serial EEPROM. Offset addresses for
proprietary port specific registers are listed in Table 19.5. Registers in this address range are referenced as
Px_REGNAME
where
x
represents the
switch port number and
REGNAME
represents the register name in Table 19.5. Reading from an address not defined in TTable 19.5 returns a value of
zero. Writes to an address not defined in Table 19.5 completes successfully, but modifies no data and has no other effect.
Figure 19.2 shows the organization of the proprietary port specific registers.