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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/i2c/summary |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/i2c/summary')
-rw-r--r-- | Documentation/i2c/summary | 75 |
1 files changed, 75 insertions, 0 deletions
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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 | |||