On Fri, 23 Nov 2012, Viresh Kumar wrote:
> On 23 November 2012 15:11, Grant Likely <grant.lik...@secretlab.ca> wrote:
> > On Fri, 23 Nov 2012 00:26:20 +0530, Viresh Kumar <viresh.ku...@linaro.org>
> > wrote:
>
> >> + - irq-trigger : IRQ trigger to use for the
> >> interrupt to the host
> >> + - irq-invert-polarity : bool, IRQ line is connected with
> >> reversed polarity
> >
> > This looks odd. Normally the interrupt polarity should be encoded in the irq
> > specifier flags field.
>
> Hi Grant and Lee Jones,
>
> This looks odd because stmpe is odd, i am taking the discussion held
> with Lee jones to this thread.
STMPE isn't odd or special in any way. :)
> So, how interrupt stuff works currently in DT..
> We have a interrupt controller IC:
>
> ic: interrupt-controller@40008000 {
> compatible = "foo";
> interrupt-controller;
> #interrupt-cells = <2>;
> ...
> };
>
> And we have a user of this IC:
>
> foo-peripheral@40048000 {
> compatible = "foo-peripheral";
> interrupt-parent = <&ic>;
> interrupts = <39 4>;
> };
>
> Here first field of "interrupts" gives interrupt line number and the second
> one
> gives polarity, interrupt type etc..
So far so good.
> All is good till now. Now, every interrupt controller supports the first
> field, but the second one depends on its capabilities. An interrupt controller
> might not have registers to configure interrupt polarity, type, etc of
> the interrupt
> it will service and so the second field wouldn't be available for them.
>
> For now just think stmpe is not a MFD and not a interrupt controller
> either. It is
> just a simple device, dev-foo.
>
> It will declare values of its interrupts field based on the type of
> interrupt controller
> that will service its interrupt and that can be anything like VIC/GIC/GPIO
> controller.
>
> Obviously nobody else than the parent IC driver can parse interrupts field
> of dev-foo, because only that driver understands the real meaning of
> these fields.
>
> Now, stmpe has a special property. It can decide the way its output
> interrupt line
> will work. i.e. its polarity and interrupt type - edle/level, etc..
> This is not commonly
> seen in any peripheral. Now my original bindings and the real question here is
> about passing this information to stmpe driver.
>
> I can't pass it in interrupts field of stmpe node, as that field
> belongs to parent
> interrupt controller of stmpe.
>
> I can't pass that from child nodes of stmpe, as we are programming the
> interrupt
> coming out of stmpe and not the interrupt coming out of stmpe-gpio or
> stmpe-keypad.
>
> And that's why i added these bindings. Please suggest me if i am still missing
> something.
Look into .xlate functions.
--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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