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i2c: slave-eeprom: update documentation 

Add more details which have either been missing ever since or describe
recent additions.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Wolfram Sang 2020-06-28 20:54:26 +02:00 committed by Wolfram Sang
parent 5f90786b31
commit 59d3d6042d
2 changed files with 20 additions and 5 deletions
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22
Documentation/i2c/slave-eeprom-backend.rst
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@ -1,14 +1,26 @@
============================== ==============================
Linux I2C slave eeprom backend Linux I2C slave EEPROM backend
============================== ==============================
by Wolfram Sang <wsa@sang-engineering.com> in 2014-15 by Wolfram Sang <wsa@sang-engineering.com> in 2014-20
This is a proof-of-concept backend which acts like an EEPROM on the connected This backend simulates an EEPROM on the connected I2C bus. Its memory contents
I2C bus. The memory contents can be modified from userspace via this file can be accessed from userspace via this file located in sysfs::
located in sysfs::
/sys/bus/i2c/devices/<device-directory>/slave-eeprom /sys/bus/i2c/devices/<device-directory>/slave-eeprom
The following types are available: 24c02, 24c32, 24c64, and 24c512. Read-only
variants are also supported. The name needed for instantiating has the form
'slave-<type>[ro]'. Examples follow:
24c02, read/write, address 0x64:
# echo slave-24c02 0x1064 > /sys/bus/i2c/devices/i2c-1/new_device
24c512, read-only, address 0x42:
# echo slave-24c512ro 0x1042 > /sys/bus/i2c/devices/i2c-1/new_device
You can also preload data during boot if a device-property named
'firmware-name' contains a valid filename (DT or ACPI only).
As of 2015, Linux doesn't support poll on binary sysfs files, so there is no As of 2015, Linux doesn't support poll on binary sysfs files, so there is no
notification when another master changed the content. notification when another master changed the content.

3
drivers/i2c/Kconfig
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@ -118,6 +118,9 @@ if I2C_SLAVE
config I2C_SLAVE_EEPROM config I2C_SLAVE_EEPROM
tristate "I2C eeprom slave driver" tristate "I2C eeprom slave driver"
help
This backend makes Linux behave like an I2C EEPROM. Please read
Documentation/i2c/slave-eeprom-backend.rst for further details.
endif endif