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. If you want I2C support, you should say Y here and also to the specific driver for your bus adapter(s) below. This I2C support can also be built as a module. If so, the module will be called i2c-core.
Say Y here if you intend to run lm-sensors 3.1.1 or older, or any other user-space package which expects i2c adapters to be class devices. If you don't know, say Y.
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 support is also available as a module. If so, the module will be called i2c-dev.
Say Y here if you want the I2C core to support the ability to handle multiplexed I2C bus topologies, by presenting each multiplexed segment as a I2C adapter. This support is also available as a module. If so, the module will be called i2c-mux.
Some I2C bus drivers require so-called "I2C algorithm" modules to work. These are basically software-only abstractions of generic I2C interfaces. This option will autoselect them so that you don't have to care. Unselect this only if you need to enable additional helper modules, for example for use with external I2C bus drivers. In doubt, say Y.
Say Y here if you want support for SMBus extensions to the I2C specification. At the moment, the only supported extension is the SMBus alert protocol. This support is also available as a module. If so, the module will be called i2c-smbus.
Say Y here if you want the I2C core to produce a bunch of debug messages to the system log. Select this if you are having a problem with I2C support and want to see more of what is going on.
Say Y here if you want the I2C algorithm drivers to produce a bunch of debug messages to the system log. Select this if you are having a problem with I2C support and want to see more of what is going on.
Say Y here if you want the I2C bus drivers to produce a bunch of debug messages to the system log. Select this if you are having a problem with I2C support and want to see more of what is going on.