Re: DT connectors, thoughts

[David Gibson]

On Thu, Jul 21, 2016 at 02:09:18PM -0500, Rob Herring wrote:
> On Thu, Jul 21, 2016 at 9:14 AM, Pantelis Antoniou
> <pantelis.antoniou@xxxxxxxxxxxx> wrote:
> > Hi David,
> >
> >> On Jul 21, 2016, at 16:42 , David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> >>
> >> On Wed, Jul 20, 2016 at 11:59:44PM +0300, Pantelis Antoniou wrote:
> >>> Hi David,
> >>>
> >>> Spent some time looking at this, and it looks like itâs going to the right direction.
> >>>
> >>> Comments inline.
> >>>
> >>>> On Jul 18, 2016, at 17:20 , David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> Here's some of my thoughts on how a connector format for the DT could
> >>>> be done.  Sorry it's taken longer than I hoped - I've been pretty
> >>>> swamped in my day job.
> >>>>
> >>>> This is pretty early thoughts, but gives an outline of the approach I
> >>>> prefer.
> 
> [...]
> 
> >>>>             i2c: i2c@... {
> >>>>             };
> >>>>             intc: intc@... {
> >>>>                     #interrupt-cells = <2>;
> >>>>             };
> >>>>     };
> >>>>
> >>>>     connectors {
> >>>>             widget1 {
> >>>>                     compatible = "foo,widget-socket";
> >>>>                     w1_irqs: irqs {
> >>>>                             interrupt-controller;
> >>>>                             #address-cells = <0>;
> >>>>                             #interrupt-cells = <1>;
> >>>>                             interrupt-map-mask = <0xffffffff>;
> >>>>                             interrupt-map = <
> >>>>                                     0 &intc 7 0
> >>>>                                     1 &intc 8 0
> >>>>                             >;
> >>>>                     };
> >>>
> >>> This is fine. We need an interrupt controller node.
> >>
> >> Actually I think we only need an interrupt nexus, not an interrupt
> >> controller (in IEEE1275 terminology).  (An interrupt controller would
> >> generally require it's own driver, to ack/mask irqs, whereas this just
> >> demonstrates the routing to an existing interrupt controller).  Which
> >> makes that example slightly incorrect (it shouldn't have the
> >> interrupt-controller property).
> >
> > Hmm, as far as I can tell we only have a concept of an interrupt controller
> > in the kernel. An interrupt nexus is something new. We should get by without
> > a driver but hacking the interrupt lookup path at DT.
> 
> Interrupt nexus is the interrupt-map property which is fully
> supported. I'd expect we'll end up with a gpio nexus (i.e. gpio-map)
> for connector gpios, too.

Exactly.  I don't know if a gpio-map is already defined, but if it's
not it should be.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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