linux-kernel - Re: [PATCH 07/15] dt: thermal: tsens: Document interrupt support in tsens driver

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Date:   Mon, 19 Aug 2019 12:40:13 +0530
From:   Amit Kucheria <amit.kucheria@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Andy Gross <andy.gross@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Zhang Rui <rui.zhang@...el.com>,
        Linux PM list <linux-pm@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>
Subject: Re: [PATCH 07/15] dt: thermal: tsens: Document interrupt support in
 tsens driver

On Sun, Aug 18, 2019 at 12:55 AM Rob Herring <robh@...nel.org> wrote:
>
> On Fri, Aug 16, 2019 at 5:02 PM Amit Kucheria <amit.kucheria@...aro.org> wrote:
> >
> > On Sat, Aug 17, 2019 at 3:06 AM Rob Herring <robh@...nel.org> wrote:
> > >
> > > On Fri, Jul 26, 2019 at 03:48:42AM +0530, Amit Kucheria wrote:
> > > > Define two new required properties to define interrupts and
> > > > interrupt-names for tsens.
> > > >
> > > > Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> > > > ---
> > > >  Documentation/devicetree/bindings/thermal/qcom-tsens.txt | 5 +++++
> > > >  1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/thermal/qcom-tsens.txt b/Documentation/devicetree/bindings/thermal/qcom-tsens.txt
> > > > index 673cc1831ee9..3d3dd5dc6d36 100644
> > > > --- a/Documentation/devicetree/bindings/thermal/qcom-tsens.txt
> > > > +++ b/Documentation/devicetree/bindings/thermal/qcom-tsens.txt
> > > > @@ -22,6 +22,8 @@ Required properties:
> > > >
> > > >  - #thermal-sensor-cells : Should be 1. See ./thermal.txt for a description.
> > > >  - #qcom,sensors: Number of sensors in tsens block
> > > > +- interrupts: Interrupts generated from Always-On subsystem (AOSS)
> > > > +- interrupt-names: The name of the interrupt e.g. "tsens0", "tsens1"
> > >
> > > How many interrupts? A name with just indices isn't too useful.
> >
> > Depending on the version of the tsens IP, there can be 1 (upper/lower
> > threshold), 2 (upper/lower + critical threshold) or 3 (upper/lower +
> > critical + zero degree) interrupts. This patch series only introduces
> > support for a single interrupt (upper/lower).
>
> I would expect a different compatible for each possibility.

We're currently using the 'qcom,tsens-v1' and 'qcom,tsens-v2'
compatibles to broadly capture the feature (and register map)
differences.

By defining the following, I should be able to check at runtime (using
platform_get_irq_by_name() as suggested) if a particular interrupt
type is available on the platform, no? So do we really require three
different compatibles?

    interrupt-names = "uplow", "crit", "cold"

[1] Respin of older SoC with a newer version of IP

> > I used the names tsens0, tsens1 to encapsulate the controller instance
> > since some SoCs have 1 controller, others have two. So we'll end up
> > with something like the following in DT:
>
> That's not really how *-names is supposed to work. The name is for
> identifying what is at each index. Or to put it another way, a driver
> should be able to use platform_get_irq_by_name(). So 'critical',
> 'zero' and something for the first one.

Fair point. I'll rework it to use "uplow", "crit" and "cold" or
something to the effect.

Is there another way I get the controller instance index in the name
in /proc/interrupts?

> > tsens0: thermal-sensor@...3000 {
> >                         compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
> >                         reg = <0 0x0c263000 0 0x1ff>, /* TM */
> >                               <0 0x0c222000 0 0x1ff>; /* SROT */
> >                         #qcom,sensors = <13>;
> >                         interrupts = <GIC_SPI 506 IRQ_TYPE_LEVEL_HIGH>,
> >                                      <GIC_SPI 508 IRQ_TYPE_LEVEL_HIGH>;
> >                         interrupt-names = "tsens0", "tsens0-critical";
> >                         #thermal-sensor-cells = <1>;
> > };
> >
> > tsens1: thermal-sensor@...5000 {
> >                         compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
> >                         reg = <0 0x0c265000 0 0x1ff>, /* TM */
> >                               <0 0x0c223000 0 0x1ff>; /* SROT */
> >                         #qcom,sensors = <8>;
> >                         interrupts = <GIC_SPI 507 IRQ_TYPE_LEVEL_HIGH>,
> >                                      <GIC_SPI 509 IRQ_TYPE_LEVEL_HIGH>;
> >                         interrupt-names = "tsens1", "tsens1-critical";
> >                         #thermal-sensor-cells = <1>;
> > }
> >
> > Does that work?
> >
> > Regards,
> > Amit
> >
> > > >  - Refer to Documentation/devicetree/bindings/nvmem/nvmem.txt to know how to specify
> > > >  nvmem cells
> > > >
> > > > @@ -40,6 +42,9 @@ tsens0: thermal-sensor@...3000 {
> > > >               reg = <0xc263000 0x1ff>, /* TM */
> > > >                       <0xc222000 0x1ff>; /* SROT */
> > > >               #qcom,sensors = <13>;
> > > > +             interrupts = <GIC_SPI 506 IRQ_TYPE_LEVEL_HIGH>;
> > > > +             interrupt-names = "tsens0";
> > > > +
> > > >               #thermal-sensor-cells = <1>;
> > > >       };
> > > >
> > > > --
> > > > 2.17.1
> > > >