Inter-Integrated Circuit controllers.

The following kernel options need to be activated:

KERNEL
 
Device Drivers  --->
   <*> I2C support  --->
      <*> I2C device interface
      [*] Autoselect pertinent helper modules
         I2C Hardware Bus support  --->
 
         Select the driver for your I2C controller, e.g.:
            <*> Intel 82801 (ICH/PCH) (i2c-i801)