From Linux i2c Wiki

Linux i2c Subsystem

This is the home of the Linux i2c subsystem.

Theory of operation

• Driver Architecture
• I2C protocol summary
• SMBus protocol summary
• 10-bit addresses information
• /dev interface documentation
• I2C adapter functionalities

Developer's documentation

• Linux 2.6 I2C development FAQ
• Conventions for use of fault codes in the I2C/SMBus stack
• How to instantiate I2C devices
• Writing kernel drivers for I2C or SMBus devices
• Upgrading I2C chip drivers to the 2.6 driver model
• i2c-stub, a fake I2C/SMBus master driver for testing purpose

Work in progress

• David Brownell was working on SMBus alert response support.
• Rodolfo Giometti is working on I2C bus multiplexing support.
• Wolfram Sang is working on moving drivers out of the directory 'drivers/i2c/chips' to ultimately remove it.
• Jean Delvare is working on dropping I2C_CLIENT_INSMOD* macros.

To-do list

• The i2c-dev driver needs to be ported to the new i2c device driver binding model. See this discussion and this bug report.
• The I2C_FUNC_PROTOCOL_MANGLING implementations need some cleanups. Many drivers implement this but don't need it.
• i2c_adapter.retries and i2c_adapter.timeout need to be clarified. Their original intent was not necessarily good nor clear, but they could still be useful, if fault codes returned by adapter drivers are also clarified.