CONFIG_I2C
  I2C (pronounce: I-square-C) is a slow serial bus protocol used in
  many micro controller applications and developed by Philips.  SMBus,
  or System Management Bus is a subset of the I2C protocol.  More
  information is contained in the directory <file:Documentation/i2c/>,
  especially in the file called "summary" there.

  Both I2C and SMBus are supported here. You will need this for
  hardware sensors support, and also for Video For Linux support.
  Specifically, if you want to use a BT848 based frame grabber/overlay
  boards under Linux, say Y here and also to "I2C bit-banging
  interfaces", below.

  If you want I2C support, you should say Y here and also to the
  specific driver for your bus adapter(s) below.  If you say Y to
  "/proc file system" below, you will then get a /proc interface which
  is documented in <file:Documentation/i2c/proc-interface>.

  This I2C support is also available as a module.  If you want to
  compile it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-core.o.

CONFIG_I2C_ALGOBIT
  This allows you to use a range of I2C adapters called bit-banging
  adapters.  Say Y if you own an I2C adapter belonging to this class
  and then say Y to the specific driver for you adapter below.

  This support is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-algo-bit.o.

CONFIG_I2C_PHILIPSPAR
  This supports parallel-port I2C adapters made by Philips.  Say Y if
  you own such an adapter.

  This driver is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-philips-par.o.

  Note that if you want support for different parallel port devices,
  life will be much easier if you compile them all as modules.

CONFIG_I2C_ELV
  This supports parallel-port I2C adapters called ELV.  Say Y if you
  own such an adapter.

  This driver is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-elv.o.

CONFIG_I2C_VELLEMAN
  This supports the Velleman K9000 parallel-port I2C adapter.  Say Y
  if you own such an adapter.

  This driver is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-velleman.o.

CONFIG_I2C_ALGOPCF
  This allows you to use a range of I2C adapters called PCF adapters.
  Say Y if you own an I2C adapter belonging to this class and then say
  Y to the specific driver for you adapter below.

  This support is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-algo-pcf.o.

CONFIG_I2C_ELEKTOR
  This supports the PCF8584 ISA bus I2C adapter.  Say Y if you own
  such an adapter.

  This driver is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-elektor.o.

CONFIG_I2C_CHARDEV
  Say Y here to use i2c-* device files, usually found in the /dev
  directory on your system.  They make it possible to have user-space
  programs use the I2C bus.  Information on how to do this is
  contained in the file <file:Documentation/i2c/dev-interface>.

  This code is also available as a module.  If you want to compile
  it as a module, say M here and read
  <file:Documentation/modules.txt>.
  The module will be called i2c-dev.o.

CONFIG_I2C_PROC
  This provides support for i2c device entries in the /proc filesystem.
  The entries will be found in /proc/sys/dev/sensors.

  This code is also available as a module. If you want to compile
  it as a module, say M here and read <file:Documentation/modules.txt>.
  The module will be called i2c-proc.o.