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1 | This is an explanation of what i2c is, and what is supported in this package. |
2 | ||
3 | I2C and SMBus | |
4 | ============= | |
5 | ||
6 | I2C (pronounce: I squared C) is a protocol developed by Philips. It is a | |
7 | slow two-wire protocol (10-400 kHz), but it suffices for many types of | |
8 | devices. | |
9 | ||
10 | SMBus (System Management Bus) is a subset of the I2C protocol. Many | |
11 | modern mainboards have a System Management Bus. There are a lot of | |
12 | devices which can be connected to a SMBus; the most notable are modern | |
13 | memory chips with EEPROM memories and chips for hardware monitoring. | |
14 | ||
15 | Because the SMBus is just a special case of the generalized I2C bus, we | |
16 | can simulate the SMBus protocol on plain I2C busses. The reverse is | |
17 | regretfully impossible. | |
18 | ||
19 | ||
20 | Terminology | |
21 | =========== | |
22 | ||
23 | When we talk about I2C, we use the following terms: | |
24 | Bus -> Algorithm | |
25 | Adapter | |
26 | Device -> Driver | |
27 | Client | |
28 | ||
29 | An Algorithm driver contains general code that can be used for a whole class | |
30 | of I2C adapters. Each specific adapter driver depends on one algorithm | |
31 | driver. | |
32 | A Driver driver (yes, this sounds ridiculous, sorry) contains the general | |
33 | code to access some type of device. Each detected device gets its own | |
34 | data in the Client structure. Usually, Driver and Client are more closely | |
35 | integrated than Algorithm and Adapter. | |
36 | ||
37 | For a given configuration, you will need a driver for your I2C bus (usually | |
38 | a separate Adapter and Algorithm driver), and drivers for your I2C devices | |
39 | (usually one driver for each device). There are no I2C device drivers | |
40 | in this package. See the lm_sensors project http://www.lm-sensors.nu | |
41 | for device drivers. | |
42 | ||
43 | ||
44 | Included Bus Drivers | |
45 | ==================== | |
46 | Note that only stable drivers are patched into the kernel by 'mkpatch'. | |
47 | ||
48 | ||
49 | Base modules | |
50 | ------------ | |
51 | ||
52 | i2c-core: The basic I2C code, including the /proc/bus/i2c* interface | |
53 | i2c-dev: The /dev/i2c-* interface | |
54 | i2c-proc: The /proc/sys/dev/sensors interface for device (client) drivers | |
55 | ||
56 | Algorithm drivers | |
57 | ----------------- | |
58 | ||
59 | i2c-algo-8xx: An algorithm for CPM's I2C device in Motorola 8xx processors (NOT BUILT BY DEFAULT) | |
60 | i2c-algo-bit: A bit-banging algorithm | |
61 | i2c-algo-pcf: A PCF 8584 style algorithm | |
62 | i2c-algo-ibm_ocp: An algorithm for the I2C device in IBM 4xx processors (NOT BUILT BY DEFAULT) | |
63 | ||
64 | Adapter drivers | |
65 | --------------- | |
66 | ||
67 | i2c-elektor: Elektor ISA card (uses i2c-algo-pcf) | |
68 | i2c-elv: ELV parallel port adapter (uses i2c-algo-bit) | |
69 | i2c-pcf-epp: PCF8584 on a EPP parallel port (uses i2c-algo-pcf) (NOT mkpatched) | |
70 | i2c-philips-par: Philips style parallel port adapter (uses i2c-algo-bit) | |
71 | i2c-adap-ibm_ocp: IBM 4xx processor I2C device (uses i2c-algo-ibm_ocp) (NOT BUILT BY DEFAULT) | |
72 | i2c-pport: Primitive parallel port adapter (uses i2c-algo-bit) | |
73 | i2c-rpx: RPX board Motorola 8xx I2C device (uses i2c-algo-8xx) (NOT BUILT BY DEFAULT) | |
74 | i2c-velleman: Velleman K8000 parallel port adapter (uses i2c-algo-bit) | |
75 |