hwmon: pmbus: Question about header files

hwmon: pmbus: Question about header files

[Vasileios Amoiridis]

Hello hwmon and PMBUS community,

I am currently studying how the PMBUS subsystem works because I am trying to
write a driver for a PSU and submit for review. I noticed that the subsystem is
quite intelligent and it manages to do most of the stuff in the pmbus_core.c
leaving a minimum amount of work to be done in the actual device driver!!

I have a question though, regarding the header files <include/linux/pmbus.h> and
<drivers/hwmon/pmbus/pmbus.h>. With my limited experience in kernel development,
I would expect that the drivers/hwmon/pmbus/pmbus.h file would include stuff
that are used only by the pmbus_core.c/pmbus.c while anything that could be
potentially used from the device drivers would go to the include/linux/pmbus.h.

Is my reasoning wrong? What was the reasoning behind the split between those 2
files?

Thanks a lot for your time!

Best regards,
Vasilis

Re: hwmon: pmbus: Question about header files

[Guenter Roeck]

On 10/3/24 15:31, Vasileios Amoiridis wrote:
> Hello hwmon and PMBUS community,
> 
> I am currently studying how the PMBUS subsystem works because I am trying to
> write a driver for a PSU and submit for review. I noticed that the subsystem is
> quite intelligent and it manages to do most of the stuff in the pmbus_core.c
> leaving a minimum amount of work to be done in the actual device driver!!
> 
> I have a question though, regarding the header files <include/linux/pmbus.h> and
> <drivers/hwmon/pmbus/pmbus.h>. With my limited experience in kernel development,
> I would expect that the drivers/hwmon/pmbus/pmbus.h file would include stuff
> that are used only by the pmbus_core.c/pmbus.c while anything that could be
> potentially used from the device drivers would go to the include/linux/pmbus.h.
> 
> Is my reasoning wrong? What was the reasoning behind the split between those 2
> files?
> 

Mostly historic. The original idea was to keep platform data in include/linux,
but at this point that has pretty much no value since all its users are (and
should be) in drivers/hwmon/pmbus/. Not worth doing anything about.

Guenter