Re: rotary encoder linux driver

Re: rotary encoder linux driver

[Johan Hovold]

On Sun, Oct 12, 2014 at 06:29:03PM -0700, tecfacet wrote:
> Hello.
> 
> I am interested in the rotary encoder kernel driver.  I am very new to
> this linux kernel driver thing.  
> 
> How do I pass the gpio and interrupt stuff to the kernel module.. I
> think it is thru the rotary_encoder.h file.. am I correct?

That should be done through the device tree these days. The binding is
documented in

	Documentation/devicetree/bindings/input/rotary-encoder.txt

in the kernel source tree.

> How does the information about encoder position etc get back to my
> user space program?  How is debounce handled?
> I am a little confused.  Is there an example of a complete working
> implementation?  I need to figure this out for school.

Have a look at the evtest program for an example:

	http://cgit.freedesktop.org/~whot/evtest

Good luck,
Johan

Re: rotary encoder linux driver

[Ben Gamari]

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Johan Hovold <johan@kernel.org> writes:

> On Sun, Oct 12, 2014 at 06:29:03PM -0700, tecfacet wrote:
>> Hello.
>> 
>> I am interested in the rotary encoder kernel driver.  I am very new to
>> this linux kernel driver thing.  
>> 
>> How do I pass the gpio and interrupt stuff to the kernel module.. I
>> think it is thru the rotary_encoder.h file.. am I correct?
>
> That should be done through the device tree these days. The binding is
> documented in
>
> 	Documentation/devicetree/bindings/input/rotary-encoder.txt
>
> in the kernel source tree.
>
You may also be interested in the device tree for a BeagleBone cape that
I recently brought up which includes an encoder,

    https://github.com/bgamari/dtb-rebuilder/blob/heaterbone-3.14/src/arm/heater-bone.dtsi#L248
    
Cheers,

- Ben


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