RE: input: Device Tree Properties for Captouch Button Device Registers

From: Ken Sloat
Date: Fri Jun 21 2019 - 10:11:42 EST


> -----Original Message-----
> From: Ken Sloat
> Sent: Wednesday, June 19, 2019 8:55 AM
> To: dmitry.torokhov@xxxxxxxxx
> Cc: Kasun Beddewela <KBeddewela@xxxxxxxxxxxxxx>; linux-
> input@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Ken Sloat
> <KSloat@xxxxxxxxxxxxxx>
> Subject: input: Device Tree Properties for Captouch Button Device Registers
>
> Hello Dmitry,
>
> We have a new input driver we are currently working on and would like to
> submit
> to the Linux kernel when we finish it. Specifically, this is a cap touch IC which
> implements potentially multiple individual proximity and cap touch buttons
> (which
> would be reported like key events as seems to be the standard). A couple of
> questions:
>
> 1. What is the preferred/proper method to expose the many registers that
> these devices have via device tree?
>
> These devices have dozens of registers, many of which might be needed
> depending
> on the individual application. It wouldn't be useful in the majority of cases to
> provide
> default values in the driver as the registers are custom tuned to the
> individual application.
>
> 2. Where should this device live? I am guessing in input/misc?
>
> Thanks,
> Ken Sloat

CC'ing people from device tree mailing list since this discussion would be relevant there as well, so the more generic question would be: For any device which requires multiple unique register configuration values per target application - what is the preferred method to expose all these via devicetree? Maybe there are some good examples of this already somewhere in the kernel drivers?

Thanks,
Ken Sloat