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-rw-r--r--Documentation/i2c/slave-eeprom-backend.rst22
1 files changed, 17 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.