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- This is an explanation of what i2c is, and what is supported in this package.
- I2C and SMBus
- =============
- I2C (pronounce: I squared C) is a protocol developed by Philips. It is a
- slow two-wire protocol (10-400 kHz), but it suffices for many types of
- devices.
- SMBus (System Management Bus) is a subset of the I2C protocol. Many
- modern mainboards have a System Management Bus. There are a lot of
- devices which can be connected to a SMBus; the most notable are modern
- memory chips with EEPROM memories and chips for hardware monitoring.
- Because the SMBus is just a special case of the generalized I2C bus, we
- can simulate the SMBus protocol on plain I2C busses. The reverse is
- regretfully impossible.
- Terminology
- ===========
- When we talk about I2C, we use the following terms:
- Bus -> Algorithm
- Adapter
- Device -> Driver
- Client
- An Algorithm driver contains general code that can be used for a whole class
- of I2C adapters. Each specific adapter driver depends on one algorithm
- driver.
- A Driver driver (yes, this sounds ridiculous, sorry) contains the general
- code to access some type of device. Each detected device gets its own
- data in the Client structure. Usually, Driver and Client are more closely
- integrated than Algorithm and Adapter.
- For a given configuration, you will need a driver for your I2C bus (usually
- a separate Adapter and Algorithm driver), and drivers for your I2C devices
- (usually one driver for each device). There are no I2C device drivers
- in this package. See the lm_sensors project http://www.lm-sensors.nu
- for device drivers.
- Included Bus Drivers
- ====================
- Note that only stable drivers are patched into the kernel by 'mkpatch'.
- Base modules
- ------------
- i2c-core: The basic I2C code, including the /proc/bus/i2c* interface
- i2c-dev: The /dev/i2c-* interface
- i2c-proc: The /proc/sys/dev/sensors interface for device (client) drivers
- Algorithm drivers
- -----------------
- i2c-algo-8xx: An algorithm for CPM's I2C device in Motorola 8xx processors (NOT BUILT BY DEFAULT)
- i2c-algo-bit: A bit-banging algorithm
- i2c-algo-pcf: A PCF 8584 style algorithm
- i2c-algo-ibm_ocp: An algorithm for the I2C device in IBM 4xx processors (NOT BUILT BY DEFAULT)
- Adapter drivers
- ---------------
- i2c-elektor: Elektor ISA card (uses i2c-algo-pcf)
- i2c-elv: ELV parallel port adapter (uses i2c-algo-bit)
- i2c-pcf-epp: PCF8584 on a EPP parallel port (uses i2c-algo-pcf) (NOT mkpatched)
- i2c-philips-par: Philips style parallel port adapter (uses i2c-algo-bit)
- i2c-adap-ibm_ocp: IBM 4xx processor I2C device (uses i2c-algo-ibm_ocp) (NOT BUILT BY DEFAULT)
- i2c-pport: Primitive parallel port adapter (uses i2c-algo-bit)
- i2c-rpx: RPX board Motorola 8xx I2C device (uses i2c-algo-8xx) (NOT BUILT BY DEFAULT)
- i2c-velleman: Velleman K8000 parallel port adapter (uses i2c-algo-bit)
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