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-MODULE: i2c-stub
-
-DESCRIPTION:
-
-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
-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 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.
-
-PARAMETERS:
-
-int chip_addr[10]:
- 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
- commands.
-
-CAVEATS:
-
-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.
-