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EEPROM and Flash Interface — Intel
®
82575EB Gigabit Ethernet Controller
324632-003 Intel
®
82575EB Gigabit Ethernet Controller
Revision: 2.1 Software Developer’s Manual and EEPROM Guide
January 2011 43
4.0 EEPROM and Flash Interface
This section describes the EEPROM and Flash interfaces supported by 82575.
4.1 EEPROM Device
The 82575 uses an EEPROM device to store product configuration information. The EEPROM is divided
into three general regions:
• Hardware Accessed — Loaded by the 82575 after power-up, PCI reset de-assertion, a D3 to D0
transition, or a software commanded EEPROM read (CTRL_EXT.EE_RST).
• Manageability Firmware Accessed
— In Pass-Through (PT) mode, loaded by the 82575 in PT mode after power up or a firmware
reset. Refer to the Intel® 82575 GbE Controller System Manageability Interface Application
Note for more information.
• Software Accessed — Used by software only. These registers are listed in this document for
convenience and are only for software and are ignored by the 82575.
The EEPROM interface supports Serial Peripheral Interface (SPI) mode 0 and expects the EEPROM to be
capable of 2 MHz operation.
The 82575 is compatible with many sizes of 4-wire serial EEPROM devices.If PT mode functionality
(SMBus or NC-SI) is desired, a 32 KB (256 Kb) serial SPI-compatible EEPROM is recommended. If no
manageability mode is desired, a 16 KB (128 Kb) serial SPI-compatible EEPROM can be used. All
EEPROMs are accessed in 16-bit words although the EEPROM is designed to also accept 8-bit data
accesses.
The 82575 automatically determines the address size to be used with the SPI EEPROM it is connected
to and sets the EEPROM Size field of the EEPROM/Flash Control (EEC) and Data Register
(EEC.EE_ADDR_SIZE; bit 10). Software uses this size to determine the EEPROM access method. The
exact size of the EEPROM is stored within one of the EEPROM words.
Note: The different EEPROM sizes have two different numbers of address bits (8 bits or 16 bits).
As a result, they must be accessed with a slightly different serial protocol. Software must be
aware of this if it accesses the EEPROM using direct access.
4.1.1 Software Accesses
The 82575 provides two different methods for software access to the EEPROM. It can either use the
built-in controller to read the EEPROM or access the EEPROM directly using the EEPROM’s 4-wire
interface.