| 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. |
| |