|This module is a very simple fake I2C/SMBus driver. It implements five
|types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, (r/w)
|word data, and (r/w) I2C block 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
|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 the i2c-tools project) to pre-load some data
| 3. load the target 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.
| The SMBus addresses to emulate chips at.
|unsigned long functionality:
| Functionality override, to disable some commands. See I2C_FUNC_*
| constants in <linux/i2c.h> for the suitable values. For example,
| value 0x1f0000 would only enable the quick, byte and byte data
|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.