On Mon, Feb 16, 2009 at 02:30:01PM -0500, Mike Murphy wrote:

On Mon, Feb 16, 2009 at 1:59 PM, Greg KH [off-list ref] wrote:

quoted

Put it on the logical device, as given to you.

quoted

I tried not to break existing functionality.  Additionally, struct
usb_xpad contains two device pointers: one to the actual USB device,
and one to an input device (see source of the in-tree xpad.c). So I
followed your kobject.txt documentation and samples to create a new
object whose sole purpose in life is to expose the sysfs interface,
without interfering with the existing device entries in the driver.
I'm not sure I see a clean way to use a single struct device here....

Put it on the input device, which is what is the per-device thing.  It's
much simpler than creating a new struct kobject.  You can even create a
subdirectory for your attributes if you use an attribute group (which
you should be doing anyway, it's much simpler that way.)

OK, one thing I'm not clear on: is there a clean API for adding
attributes to an existing struct device, or do I need to "subclass" it
(the C containment and delegation approach)?

device_create_file()