[PATCH v2 1/2] doc/devicetree: Add Aspeed VIC bindings

[Joel Stanley]

On Fri, May 13, 2016 at 2:50 AM, Rob Herring <robh at kernel.org> wrote:
> On Wed, May 11, 2016 at 8:01 PM, Benjamin Herrenschmidt
> <benh at kernel.crashing.org> wrote:
>> On Wed, 2016-05-11 at 09:33 -0500, Rob Herring wrote:
>>> > +- interrupt-controller : Identifies the node as an interrupt controller
>>> > +- #interrupt-cells : Specifies the number of cells needed to encode an
>>> > +  interrupt source. The value shall be 1.
>>>
>>> No need for level vs. edge flags?
>>
>> That's an open question. Most interrupts are fixed. A handful of GPIOs
>> can be configured either way. For now I am relying on uboot setting up
>> the right config for them and I read it back at boot time, but we could
>> make it part of the binding I suppose.
>
> It is almost standard to just use 2 cells here even if reserved for
> future use. Especially since the IP block seems to have registers to
> control that.

Yep, makes sense. I've added this to the bindings document.

I was trying to use the second cell in our driver:

  static struct irq_domain_ops avic_dom_ops = {
          .map = avic_map,
         .xlate = irq_domain_xlate_twocell,
  };

 So we have irq_domain_xlate_twocell to parse the device tree and
grabs the type property from the second cell.

In avic_map we set the irq handler:

         if (vic->edge_sources[sidx] & sbit) {
                 /* TODO: Check aginst type from dt and warn if not edge */
                 irq_set_chip_and_handler(irq, &avic_chip, handle_edge_irq);
         } else {
                 /* TODO: Check aginst type from dt and warn if not level */
                 irq_set_chip_and_handler(irq, &avic_chip, handle_level_irq);
         }

However, we don't have the type here, so we can't use it to check that
we're setting the correct edge/level callback (or use it to set the
register in the future if we want to use the device tree to override
the bootloader settings).

I had a look at some other drivers and they don't seem to use the dt
property when mapping the irq. What am I missing here?

Cheers,

Joel