Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 96 insertions, 0 deletions

diff --git a/Documentation/misc-devices/eeprom b/Documentation/misc-devices/eeprom
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+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.