Re: [RFC/PATCH 0/1] Quadrature Encoder Support

[William Breathitt Gray <vilhelm.gray@gmail.com>]

On Sun, Sep 15, 2019 at 02:53:47PM +0100, Jonathan Cameron wrote:
> On Mon,  9 Sep 2019 15:16:04 +0300
> Felipe Balbi <felipe.balbi@linux.intel.com> wrote:
> 
> > Hi,
> > 
> > Here's a simple RFC for Intel's Quadrature Encoder. Let me make it clear
> > that I don't mean we should the following patch as is, rather I'd like
> > to open the discussion to, perhaps, extending Industrial Automation
> > Framework with support for Quadrature Encoders.
> > 
> > Let me know if you think IIO would be correct place for such devices,
> > then I can start reworking the driver to provide an IIO-compliant
> > interface.
> > 
> > I'm thinking we would need standard sysfs files for configuring the QEP
> > into single-shot QEP mode or buffered Capture mode, configure thresholds
> > and other details.
> 
> Hi Felipe,
> 
> Fairly recently, similar concerns that IIO didn't really suite these
> devices lead William to create a specific 'counters' subsystem.
> +CC William.
> 
> It may not address all of your requirements yet, but I would imagine it
> is a better fit than IIO would ever be.  We have moved all the older
> counter drivers out of IIO and across to this new subsystem.
> 
> Thanks,
> 
> Jonathan

Felipe,

Take a look at the Generic Counter interface, it may be what you need:
https://www.kernel.org/doc/html/latest/driver-api/generic-counter.html

There are some existing quadrature encoder counter devices using this
interface already; look at the files under drivers/counter for
reference.

This interface is still relatively new, so if you have any problems just
shoot me an email and I'll be happy to help. :-)

William Breathitt Gray

> 
> 
> > 
> > Cheers
> > 
> > Felipe Balbi (1):
> >   misc: introduce intel QEP
> > 
> >  drivers/misc/Kconfig     |   7 +
> >  drivers/misc/Makefile    |   1 +
> >  drivers/misc/intel-qep.c | 813 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 821 insertions(+)
> >  create mode 100644 drivers/misc/intel-qep.c
> > 
>