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authorWolfram Sang <wsa+renesas@sang-engineering.com>2020-06-28 20:54:26 +0200
committerWolfram Sang <wsa@kernel.org>2020-07-04 08:17:53 +0200
commit59d3d6042d432f36e206127de0dab7f9319762d5 (patch)
treeff8f968810777f6e14b1698fec077b06114a02a7
parent5f90786b31fb7d1e199a8999d46c4e3aea672e11 (diff)
downloadlinux-stericsson-59d3d6042d432f36e206127de0dab7f9319762d5.tar.gz
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>
-rw-r--r--Documentation/i2c/slave-eeprom-backend.rst22
-rw-r--r--drivers/i2c/Kconfig3
2 files changed, 20 insertions, 5 deletions
diff --git a/Documentation/i2c/slave-eeprom-backend.rst b/Documentation/i2c/slave-eeprom-backend.rst
index 0b8cd83698e0..38d951f10302 100644
--- a/Documentation/i2c/slave-eeprom-backend.rst
+++ b/Documentation/i2c/slave-eeprom-backend.rst
@@ -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.
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index ef39c83aaf33..6e2d0d2531c5 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -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