| 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. | |