From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-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! --- Documentation/i2c/summary | 75 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 Documentation/i2c/summary (limited to 'Documentation/i2c/summary') diff --git a/Documentation/i2c/summary b/Documentation/i2c/summary new file mode 100644 index 000000000000..41dde8776791 --- /dev/null +++ b/Documentation/i2c/summary @@ -0,0 +1,75 @@ +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) + -- cgit v1.2.3