1MODULE: i2c-stub 2 3DESCRIPTION: 4 5This module is a very simple fake I2C/SMBus driver. It implements four 6types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, and 7(r/w) word data. 8 9You need to provide chip addresses as a module parameter when loading this 10driver, which will then only react to SMBus commands to these addresses. 11 12No hardware is needed nor associated with this module. It will accept write 13quick commands to the specified addresses; it will respond to the other 14commands (also to the specified addresses) by reading from or writing to 15arrays in memory. It will also spam the kernel logs for every command it 16handles. 17 18A pointer register with auto-increment is implemented for all byte 19operations. This allows for continuous byte reads like those supported by 20EEPROMs, among others. 21 22The typical use-case is like this: 23 1. load this module 24 2. use i2cset (from lm_sensors project) to pre-load some data 25 3. load the target sensors chip driver module 26 4. observe its behavior in the kernel log 27 28There's a script named i2c-stub-from-dump in the i2c-tools package which 29can load register values automatically from a chip dump. 30 31PARAMETERS: 32 33int chip_addr[10]: 34 The SMBus addresses to emulate chips at. 35 36CAVEATS: 37 38If your target driver polls some byte or word waiting for it to change, the 39stub could lock it up. Use i2cset to unlock it. 40 41If the hardware for your driver has banked registers (e.g. Winbond sensors 42chips) this module will not work well - although it could be extended to 43support that pretty easily. 44 45If you spam it hard enough, printk can be lossy. This module really wants 46something like relayfs. 47 48