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. No hardware is needed nor associated with this module. It will accept write quick commands to all addresses; it will respond to the other commands (also to all addresses) by reading from or writing to an array 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 CAVEATS: There are independent arrays for byte/data and word/data commands. Depending on if/how a target driver mixes them, you'll need to be careful. 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.