linux-kernel - Re: [PATCH v5 1/3] dt-bindings: interrupt-controller: Add Actions SIRQ controller binding

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Message-ID: <CAL_JsqLvXDFL6vFooPYLJ1QnZ7L756fNesXo-LW_scs9rV-zPA@mail.gmail.com>
Date:   Wed, 26 Aug 2020 16:48:38 -0600
From:   Rob Herring <robh@...nel.org>
To:     Cristian Ciocaltea <cristian.ciocaltea@...il.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Andreas Färber <afaerber@...e.de>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-actions@...ts.infradead.org
Subject: Re: [PATCH v5 1/3] dt-bindings: interrupt-controller: Add Actions
 SIRQ controller binding

On Wed, Aug 26, 2020 at 3:42 PM Cristian Ciocaltea
<cristian.ciocaltea@...il.com> wrote:
>
> Hi Rob,
>
> Thanks for the review!
>
> On Tue, Aug 25, 2020 at 04:09:13PM -0600, Rob Herring wrote:
> > On Wed, Aug 19, 2020 at 07:37:56PM +0300, Cristian Ciocaltea wrote:
> > > Actions Semi Owl SoCs SIRQ interrupt controller is found in S500, S700
> > > and S900 SoCs and provides support for handling up to 3 external
> > > interrupt lines.
> > >
> > > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...il.com>
> > > ---
> > > Changes in v5:
> > >  - Updated controller description statements both in the commit message
> > >    and the binding doc
> > >
> > >  .../actions,owl-sirq.yaml                     | 68 +++++++++++++++++++
> > >  1 file changed, 68 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/actions,owl-sirq.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/actions,owl-sirq.yaml b/Documentation/devicetree/bindings/interrupt-controller/actions,owl-sirq.yaml
> > > new file mode 100644
> > > index 000000000000..cf9b7a514e4e
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/interrupt-controller/actions,owl-sirq.yaml
> > > @@ -0,0 +1,68 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/interrupt-controller/actions,owl-sirq.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Actions Semi Owl SoCs SIRQ interrupt controller
> > > +
> > > +maintainers:
> > > +  - Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > +  - Cristian Ciocaltea <cristian.ciocaltea@...il.com>
> > > +
> > > +description: |
> > > +  This interrupt controller is found in the Actions Semi Owl SoCs (S500, S700
> > > +  and S900) and provides support for handling up to 3 external interrupt lines.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    oneOf:
> > > +      - items:
> > > +        - enum:
> > > +          - actions,s500-sirq
> > > +          - actions,s700-sirq
> > > +          - actions,s900-sirq
> > > +        - const: actions,owl-sirq
> > > +      - const: actions,owl-sirq
> >
> > This should be dropped. You should always have the SoC specific
> > compatible.
>
> Sure, I will get rid of the 'owl-sirq' compatible.
>
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  interrupt-controller: true
> > > +
> > > +  '#interrupt-cells':
> > > +    const: 2
> > > +    description:
> > > +      The first cell is the input IRQ number, between 0 and 2, while the second
> > > +      cell is the trigger type as defined in interrupt.txt in this directory.
> > > +
> > > +  'actions,ext-interrupts':
> > > +    description: |
> > > +      Contains the GIC SPI IRQ numbers mapped to the external interrupt
> > > +      lines. They shall be specified sequentially from output 0 to 2.
> > > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > > +    minItems: 3
> > > +    maxItems: 3
> >
> > Can't you use 'interrupts' here?
>
> This was actually my initial idea, but it might confuse the users since
> this is not following the parent controller IRQ specs, i.e. the trigger
> type is set internally by the SIRQ driver, it's not taken from DT.

Then what's the 2nd cell for?

> Please see the DTS sample bellow where both devices are on the same
> level and have GIC as interrupt parent. The 'interrupts' property
> in the sirq node looks incomplete now. That is why I decided to use
> a custom name for it, although I'm not sure it's the most relevant one,
> I am open to any other suggestion.
>
> i2c0: i2c@...70000 {
>   [...]
>   interrupts = <GIC_SPI 25 IRQ_TYPE_LEVEL_HIGH>;
>   [...]
> };
>
> sirq: interrupt-controller@...b0200 {
>   [...]
>   interrupt-controller;
>   #interrupt-cells = <2>;
>   interrupts = <13>, /* SIRQ0 */
>                <14>, /* SIRQ1 */
>                <15>; /* SIRQ2 */

This isn't valid if the GIC is the parent as you have to have 3 cells
for each interrupt. Ultimately the GIC trigger type has to be
something. Is it fixed or passed thru? If the latter, just use 0
(IRQ_TYPE_NONE) if the GIC trigger mode is not fixed. Having some sort
of translation of the trigger is pretty common.

Rob