108 lines
4.4 KiB
ReStructuredText
108 lines
4.4 KiB
ReStructuredText
|
====================
|
||
|
|
Kernel driver eeprom
|
||
|
|
====================
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
|
||
|
|
* Any EEPROM chip in the designated address range
|
||
|
|
|
||
|
|
Prefix: 'eeprom'
|
||
|
|
|
||
|
|
Addresses scanned: I2C 0x50 - 0x57
|
||
|
|
|
||
|
|
Datasheets: Publicly available from:
|
||
|
|
|
||
|
|
Atmel (www.atmel.com),
|
||
|
|
Catalyst (www.catsemi.com),
|
||
|
|
Fairchild (www.fairchildsemi.com),
|
||
|
|
Microchip (www.microchip.com),
|
||
|
|
Philips (www.semiconductor.philips.com),
|
||
|
|
Rohm (www.rohm.com),
|
||
|
|
ST (www.st.com),
|
||
|
|
Xicor (www.xicor.com),
|
||
|
|
and others.
|
||
|
|
|
||
|
|
========= ============= ============================================
|
||
|
|
Chip Size (bits) Address
|
||
|
|
========= ============= ============================================
|
||
|
|
24C01 1K 0x50 (shadows at 0x51 - 0x57)
|
||
|
|
24C01A 1K 0x50 - 0x57 (Typical device on DIMMs)
|
||
|
|
24C02 2K 0x50 - 0x57
|
||
|
|
24C04 4K 0x50, 0x52, 0x54, 0x56
|
||
|
|
(additional data at 0x51, 0x53, 0x55, 0x57)
|
||
|
|
24C08 8K 0x50, 0x54 (additional data at 0x51, 0x52,
|
||
|
|
0x53, 0x55, 0x56, 0x57)
|
||
|
|
24C16 16K 0x50 (additional data at 0x51 - 0x57)
|
||
|
|
Sony 2K 0x57
|
||
|
|
|
||
|
|
Atmel 34C02B 2K 0x50 - 0x57, SW write protect at 0x30-37
|
||
|
|
Catalyst 34FC02 2K 0x50 - 0x57, SW write protect at 0x30-37
|
||
|
|
Catalyst 34RC02 2K 0x50 - 0x57, SW write protect at 0x30-37
|
||
|
|
Fairchild 34W02 2K 0x50 - 0x57, SW write protect at 0x30-37
|
||
|
|
Microchip 24AA52 2K 0x50 - 0x57, SW write protect at 0x30-37
|
||
|
|
ST M34C02 2K 0x50 - 0x57, SW write protect at 0x30-37
|
||
|
|
========= ============= ============================================
|
||
|
|
|
||
|
|
|
||
|
|
Authors:
|
||
|
|
- Frodo Looijaard <frodol@dds.nl>,
|
||
|
|
- Philip Edelbrock <phil@netroedge.com>,
|
||
|
|
- Jean Delvare <jdelvare@suse.de>,
|
||
|
|
- Greg Kroah-Hartman <greg@kroah.com>,
|
||
|
|
- IBM Corp.
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
This is a simple EEPROM module meant to enable reading the first 256 bytes
|
||
|
|
of an EEPROM (on a SDRAM DIMM for example). However, it will access serial
|
||
|
|
EEPROMs on any I2C adapter. The supported devices are generically called
|
||
|
|
24Cxx, and are listed above; however the numbering for these
|
||
|
|
industry-standard devices may vary by manufacturer.
|
||
|
|
|
||
|
|
This module was a programming exercise to get used to the new project
|
||
|
|
organization laid out by Frodo, but it should be at least completely
|
||
|
|
effective for decoding the contents of EEPROMs on DIMMs.
|
||
|
|
|
||
|
|
DIMMS will typically contain a 24C01A or 24C02, or the 34C02 variants.
|
||
|
|
The other devices will not be found on a DIMM because they respond to more
|
||
|
|
than one address.
|
||
|
|
|
||
|
|
DDC Monitors may contain any device. Often a 24C01, which responds to all 8
|
||
|
|
addresses, is found.
|
||
|
|
|
||
|
|
Recent Sony Vaio laptops have an EEPROM at 0x57. We couldn't get the
|
||
|
|
specification, so it is guess work and far from being complete.
|
||
|
|
|
||
|
|
The Microchip 24AA52/24LCS52, ST M34C02, and others support an additional
|
||
|
|
software write protect register at 0x30 - 0x37 (0x20 less than the memory
|
||
|
|
location). The chip responds to "write quick" detection at this address but
|
||
|
|
does not respond to byte reads. If this register is present, the lower 128
|
||
|
|
bytes of the memory array are not write protected. Any byte data write to
|
||
|
|
this address will write protect the memory array permanently, and the
|
||
|
|
device will no longer respond at the 0x30-37 address. The eeprom driver
|
||
|
|
does not support this register.
|
||
|
|
|
||
|
|
Lacking functionality
|
||
|
|
---------------------
|
||
|
|
|
||
|
|
* Full support for larger devices (24C04, 24C08, 24C16). These are not
|
||
|
|
typically found on a PC. These devices will appear as separate devices at
|
||
|
|
multiple addresses.
|
||
|
|
|
||
|
|
* Support for really large devices (24C32, 24C64, 24C128, 24C256, 24C512).
|
||
|
|
These devices require two-byte address fields and are not supported.
|
||
|
|
|
||
|
|
* Enable Writing. Again, no technical reason why not, but making it easy
|
||
|
|
to change the contents of the EEPROMs (on DIMMs anyway) also makes it easy
|
||
|
|
to disable the DIMMs (potentially preventing the computer from booting)
|
||
|
|
until the values are restored somehow.
|
||
|
|
|
||
|
|
Use
|
||
|
|
---
|
||
|
|
|
||
|
|
After inserting the module (and any other required SMBus/i2c modules), you
|
||
|
|
should have some EEPROM directories in ``/sys/bus/i2c/devices/*`` of names such
|
||
|
|
as "0-0050". Inside each of these is a series of files, the eeprom file
|
||
|
|
contains the binary data from EEPROM.
|