| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647 |
- MODULE: i2c-stub
- DESCRIPTION:
- This module is a very simple fake I2C/SMBus driver. It implements four
- types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, and
- (r/w) word data.
- You need to provide chip addresses as a module parameter when loading this
- driver, which will then only react to SMBus commands to these addresses.
- No hardware is needed nor associated with this module. It will accept write
- quick commands to the specified addresses; it will respond to the other
- commands (also to the specified addresses) by reading from or writing to
- arrays in memory. It will also spam the kernel logs for every command it
- handles.
- A pointer register with auto-increment is implemented for all byte
- operations. This allows for continuous byte reads like those supported by
- EEPROMs, among others.
- The typical use-case is like this:
- 1. load this module
- 2. use i2cset (from lm_sensors project) to pre-load some data
- 3. load the target sensors chip driver module
- 4. observe its behavior in the kernel log
- There's a script named i2c-stub-from-dump in the i2c-tools package which
- can load register values automatically from a chip dump.
- PARAMETERS:
- int chip_addr[10]:
- The SMBus addresses to emulate chips at.
- CAVEATS:
- If your target driver polls some byte or word waiting for it to change, the
- stub could lock it up. Use i2cset to unlock it.
- If the hardware for your driver has banked registers (e.g. Winbond sensors
- chips) this module will not work well - although it could be extended to
- support that pretty easily.
- If you spam it hard enough, printk can be lossy. This module really wants
- something like relayfs.
|
