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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
I2C bus. The memory contents can be modified from userspace via this file
located in sysfs::
This backend simulates an EEPROM on the connected I2C bus. Its memory contents
can be accessed from userspace via this file located in sysfs::
/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
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
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