mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-25 15:30:54 +07:00
569be443e3
This mimics the behavior of actual SMBus chips better. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Mark M. Hoffman <mhoffman@lightlink.com>
48 lines
1.6 KiB
Plaintext
48 lines
1.6 KiB
Plaintext
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.
|
|
|
|
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 lm_sensors project) to pre-load some data
|
|
3. load the target sensors 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.
|
|
|
|
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.
|
|
|