I2C under Linux
The first possibility to access I2C devices under Linux is using a kernel driver for your device.
In case you want to access the I2C bus from userspace, you have to use the i2c-dev driver.
You can do this using the i2c-tools package or by writing a custom program.
The i2c-tools documentation can be found here:
http://www.lm-sensors.org/wiki/i2cToolsDocumentation
If you want to use the interface with a custom program the relevant documentation is here: