Is there any way to add an attribute under sysfs at the “platform” level?

[Greg KH]

On Sun, Jun 18, 2017 at 05:38:36PM +0300, Roman Storozhenko wrote:
> Hello everybody!
> 
> I am trying to modify "pcspkr" driver undere linux kernel source tree. I added a new line there:
> 
> sample_id_dir = kobject_create_and_add("devices/platform/pcspkr/sample", NULL);

Ick, really?  What are you trying to do with "raw" kobjects?

> It works and creates kobject without errors. I checked this in the driver code and in the dmesg output. But "sample" catalog isn't appear under "/sys/devices/platform/pcspkr/".

Are you sure?  Odds are you really did create a kobject with that name,
but note, the name will have '/' characters in it :)

If you want a kobject in a specific directory, you have to give it the
parent kobject directory directly, you can not give a "path" to the
kobject name, sorry, that's not how it works.

The kobject documentation should help you out here, have you read it?

good luck!

greg k-h