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.
+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 a chip address as a module parameter when loading
-this driver, which will then only react to SMBus commands to this address.
+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 one address; it will respond to the other commands (also
-to one address) by reading from or writing to an array in memory. It will
-also spam the kernel logs for every command it handles.
+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
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
+ 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:
- The SMBus address to emulate a chip at.
+int chip_addr[10]:
+ The SMBus addresses to emulate chips at.
-CAVEATS:
+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.
-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.
+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.
chips) this module will not work well - although it could be extended to
support that pretty easily.
-Only one chip address is supported - although this module could be
-extended to support more.
-
If you spam it hard enough, printk can be lossy. This module really wants
something like relayfs.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff