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author | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
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committer | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
commit | 871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch) | |
tree | 8718f573808810c2a1e8cb8fb6ac469093ca2784 /Documentation/i2c/summary | |
parent | 9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff) | |
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Moved, renamed, and deleted files
The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.
Diffstat (limited to 'Documentation/i2c/summary')
-rw-r--r-- | Documentation/i2c/summary | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/i2c/summary b/Documentation/i2c/summary new file mode 100644 index 00000000..13ab076d --- /dev/null +++ b/Documentation/i2c/summary @@ -0,0 +1,47 @@ +I2C and SMBus +============= + +I2C (pronounce: I squared C) is a protocol developed by Philips. It is a +slow two-wire protocol (variable speed, up to 400 kHz), with a high speed +extension (3.4 MHz). It provides an inexpensive bus for connecting many +types of devices with infrequent or low bandwidth communications needs. +I2C is widely used with embedded systems. Some systems use variants that +don't meet branding requirements, and so are not advertised as being I2C. + +SMBus (System Management Bus) is based on the I2C protocol, and is mostly +a subset of I2C protocols and signaling. Many I2C devices will work on an +SMBus, but some SMBus protocols add semantics beyond what is required to +achieve I2C branding. Modern PC mainboards rely on SMBus. The most common +devices connected through SMBus are RAM modules configured using I2C EEPROMs, +and hardware monitoring chips. + +Because the SMBus is mostly a subset of the generalized I2C bus, we can +use its protocols on many I2C systems. However, there are systems that don't +meet both SMBus and I2C electrical constraints; and others which can't +implement all the common SMBus protocol semantics or messages. + + +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 either depends on one algorithm +driver, or includes its own implementation. + +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, and +drivers for your I2C devices (usually one driver for each device). + +At this time, Linux only operates I2C (or SMBus) in master mode; you can't +use these APIs to make a Linux system behave as a slave/device, either to +speak a custom protocol or to emulate some other device. |