Re: [PATCH v2 1/5] dt-bindings: interrupt-controller: Update STM32 EXTI interrupt controller

[Alexandre TORGUE]

Hi Marc

On 12/20/21 1:34 PM, Marc Zyngier wrote:
> On Fri, 17 Dec 2021 13:39:11 +0000,
> Alexandre TORGUE <alexandre.torgue@xxxxxxxxxxx> wrote:
> > On 12/16/21 9:15 PM, Rob Herring wrote:
> > > On Wed, Dec 15, 2021 at 11:58:43AM +0100, Alexandre Torgue wrote:
> > > > Document new entry "st,exti-mapping" which links EXTI lines with GIC
> > > > interrupt lines and add an include file to define EXTI interrupt type.
> > > >
> > > > Signed-off-by: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/st,stm32-exti.yaml b/Documentation/devicetree/bindings/interrupt-controller/st,stm32-exti.yaml
> > > > index d19c881b4abc..e08bb51e97a8 100644
> > > > --- a/Documentation/devicetree/bindings/interrupt-controller/st,stm32-exti.yaml
> > > > +++ b/Documentation/devicetree/bindings/interrupt-controller/st,stm32-exti.yaml
> > > > @@ -41,6 +41,17 @@ properties:
> > > >        description:
> > > >          Interrupts references to primary interrupt controller
> > > >    +  st,exti-mapping:
> > > > +    $ref: "/schemas/types.yaml#/definitions/uint32-matrix"
> > > > +    description: |
> > > > +            Define mapping between EXTI lines and GIC irq lines. Should be:
> > > > +            st,exti-mapping = <EXTI_LINE GIC_IRQ EXTI_TYPE>, ...;
> > > > +            With:
> > > > +            - EXTI_LINE: EXTI line number.
> > > > +            - GIC_IRQ: GIC IRQ associated to the EXTI line.
> > > > +            - EXTI_TYPE: STM32_EXTI_TYPE_CONFIGURABLE or STM32_EXTI_TYPE_DIRECT.
> > > > +              Defined in include/dt-bindings/interrupt-controller/stm32-exti.h
> > >
> > > No custom properties for this. See[1][2][3].
> >
> > Thanks for inputs. In my case the mapping consists to map an EXTI line
> > with a GIC irq line which could be done using interrupt-map (avoiding
> > to parse it in my driver).
>
> The problem is that 'interrupt-map' defines an interrupt mapping
> between an input and an output, and that mentioning the GIC in such a
> table will only result in your EXTI to be bypassed.
>
> 'interrupt-map' really is a dispatch table for targeting an interrupt
> controller (or multiple controllers, even), but really isn't the
> correct tool to carry configuration informations to an interrupt
> controller driver.

Ok so let's forget "interrupt-map"

> > But for each EXTI/GIC association I would
> > like also to describe the EXTI_TYPE (which actually describe the well
> > irqchip to use inside my exti driver) . This property is not generic
> > and so I assume I can't use a generic binding such "interrupt-map".
> >
> > If the solution consists to use a common binding (i.e. interrupt-map)
> > plus a conversion table in exti driver to affect the well irq_chip to
> > the well EXTI line then we could envisage to keep the whole mapping
> > inside the driver (even if it's not the best solution).
>
> A possible solution would be to have:
>
> - A set of standard 'interrupts' properties describing the output
> signals
>
> - A set of properties describing the input to output mapping (if
> relevant) and additional configuration information that for the
> interrupt controller driver.

Does it means to have my own description of "interrupt" property using 
xlate function in EXTI driver ?

something like that:

interrupt = <GIC_SPI 6 EXTI_LINE EXTI_TYPE>, ...

regards
Alex
> 	M.