PCI7510 datasheet(45/234 Pages) TI

45 / 234 page

3–5

SCL

SDA

VCC

SCL

SDA

PCI7510

Serial

ROM

Figure 3–3. Serial ROM Application

3.5.4

Loading CardBus (Function 0) Subsystem Identification

The subsystem vendor ID register (PCI offset 40h, see Section 4.27) and subsystem ID register (PCI offset 42h, see

Section 4.28) make up a doubleword of PCI configuration space for function 0. This doubleword register is used for

system and option card (mobile dock) identification purposes and is required by some operating systems.

Implementation of this unique identifier register is a PC 99/PC 2001 requirement.

The PCI7510 device offers two mechanisms to load a read-only value into the subsystem registers. The first

mechanism relies upon the system BIOS providing the subsystem ID value. The default access mode to the

subsystem registers is read-only, but can be made read/write by setting bit 5 (SUBSYSRW) in the system control

into the registers at PCI offset 40h. The BIOS must clear the SUBSYSRW bit such that the subsystem vendor ID

implementing the serial electrically erasable programmable ROM (EEPROM).

In some conditions, such as in a docking environment, the subsystem vendor ID register and subsystem ID register

must be loaded with a unique identifier via a serial EEPROM. The PCI7510 device loads the data from the serial

EEPROM after a reset of the primary bus. Note that the SUSPEND input gates the PCI reset from the entire PCI7510

core, including the serial-bus state machine (see Section 3.9.6, Suspend Mode, for details on using SUSPEND).

The PCI7510 device provides a two-line serial-bus host controller that can interface to a serial EEPROM. See

Section 3.7, Serial EEPROM Interface, for details on the two-wire serial-bus controller and applications.

3.5.4.1 Function 2 Subsystem Identification

The subsystem identification register is used for system and option card identification purposes. This register can

be initialized from the serial EEPROM or programmed via the subsystem access register at offset F8h in the PCI

configuration space (see Section 7.25, Subsystem Access Register). See Table 7–22 for a complete description of

the register contents.

Write access to the subsystem access register updates the subsystem identification registers identically to

OHCI-Lynx

. The system ID value written to this register may also be read back from this register. See Table 7–22

for a complete description of the register contents.

3.5.4.2 Function 3 Subsystem Identification

The subsystem identification register is used for system and option card identification purposes. This register can

be initialized from the serial EEPROM or programmed via the subsystem access register at offset F8h in the PCI

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