proc-interface
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上传日期:2013-02-24
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- i2c-core is the core i2c module (surprise!) which offers general routines on
- which other modules build. You will find that all i2c-related modules depend
- on this module, so it will (need to) be loaded whenever another i2c-related
- module is loaded. Seen from the outside, the most interesting is the /proc
- interface. Note that there is no corresponding sysctl interface!
- /proc/bus/i2c
- =============
- Whenever i2c-core is loaded, you will find a file /proc/bus/i2c, which lists
- all currently registered I2C adapters. Each line contains exactly one
- I2C adapter. Each line has the following format: "i2c-%dt%9st%-32s't%-32sn",
- which works out to four columns separated by tabs. Note that the file
- will be empty, if no adapters are registered at all.
- Adapters are numbered from 0 upwards. The first column contains the number
- of the adapter, for example "i2c-4" for adapter 4. The name listed is also
- the name of the /proc file which lists all devices attached to it, and
- of the /dev file which corresponds to this adapter.
- The second column documents what kind of adapter this is. Some adapters
- understand the full I2C protocol, others only a subset called SMBus,
- and yet others are some kind of pseudo-adapters that do not understand
- i2c at all. Possible values in here are "i2c", "smbus", "i2c/smbus"
- and "dummy". Because the SMBus protocol can be fully emulated by i2c
- adapters, if you see "i2c" here, SMBus is supported too. There may
- be some future adapters which support both specific SMBus commands and
- general I2C, and they will display "i2c/smbus".
- The third and fourth column are respectively the algorithm and adapter
- name of this adapter. Each adapter is associated with an algorithm,
- and several adapters can share the same algorithm. The combination of
- algorithm name and adapter name should be unique for an adapter, but
- you can't really count on that yet.
- /proc/bus/i2c-*
- ===============
- Each registered adapter gets its own file in /proc/bus/, which lists
- the devices registered to the adapter. Each line in such a file contains
- one registered device. Each line has the following format:
- "%02xt%-32st%-32sn", which works out to three columns separated by
- tabs. Note that this file can be empty, if no devices are found on
- the adapter.
- The first column contains the (hexadecimal) address of the client. As
- only 7-bit addresses are supported at this moment, two digits are
- enough.
- The second and third column are respectively the client name and the
- driver name of this client. Each client is associated with a driver,
- and several clients can share the same driver.