linux-kernel - Re: [PATCH 4/8] dt-bindings: arm: mediatek: Add new document bindings for APU

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Date:   Fri, 16 Apr 2021 11:01:10 +0800
From:   Flora Fu <flora.fu@...iatek.com>
To:     Rob Herring <robh@...nel.org>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Pi-Cheng Chen <pi-cheng.chen@...iatek.com>,
        Chiawen Lee <chiawen.lee@...iatek.com>,
        Chun-Jie Chen <chun-jie.chen@...iatek.com>,
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH 4/8] dt-bindings: arm: mediatek: Add new document
 bindings for APU

On Thu, 2021-04-15 at 16:24 -0500, Rob Herring wrote:
> On Mon, Apr 12, 2021 at 1:45 AM Flora Fu <flora.fu@...iatek.com> wrote:
> >
> > On Fri, 2021-04-09 at 13:25 -0500, Rob Herring wrote:
> > > On Wed, Apr 07, 2021 at 11:28:02AM +0800, Flora Fu wrote:
> > > > Document the apusys bindings.
> > > >
> > > > Signed-off-by: Flora Fu <flora.fu@...iatek.com>
> > > > ---
> > > >  .../arm/mediatek/mediatek,apusys.yaml         | 56 +++++++++++++++++++
> > > >  1 file changed, 56 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/arm/mediatek/mediatek,apusys.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/arm/mediatek/mediatek,apusys.yaml b/Documentation/devicetree/bindings/arm/mediatek/mediatek,apusys.yaml
> > > > new file mode 100644
> > > > index 000000000000..dc04a46f1bad
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/arm/mediatek/mediatek,apusys.yaml
> > > > @@ -0,0 +1,56 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: https://urldefense.com/v3/__http://devicetree.org/schemas/arm/mediatek/mediatek,apusys.yaml*__;Iw!!CTRNKA9wMg0ARbw!3ryKFTA2CvsVss4Pt2ZOG7wv4jgR-2LPxuGn30IxFmpxoxSRdzNdf8FrAYYvZWcw$
> > > > +$schema: https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!3ryKFTA2CvsVss4Pt2ZOG7wv4jgR-2LPxuGn30IxFmpxoxSRdzNdf8FrARlhCQ0w$
> > > > +
> > > > +title: MediaTek APUSYS Controller
> > > > +
> > > > +maintainers:
> > > > +  - Flora Fu <flora.fu@...iatek.com>
> > > > +
> > > > +description:
> > > > +  The Mediatek apusys controller provides functional configurations and clocks
> > > > +  to the system.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    items:
> > > > +      - enum:
> > > > +          - mediatek,mt8192-apu_mbox
> > > > +          - mediatek,mt8192-apu_conn
> > > > +          - mediatek,mt8192-apu_vcore
> > >
> > > s/_/-/
> > >
> >
> > OK. I will update expression strings in the next version.
> >
> > > > +      - const: syscon
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +  '#clock-cells':
> > > > +    const: 1
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +
> > > > +additionalProperties: false
> > > > +
> > > > +examples:
> > > > +  - |
> > > > +    apu_mbox: apu_mbox@...00000 {
> > >
> > > mailbox@...? Is this a mailbox provider?
> > >
> >
> > Yes, the apu_mbox is the for setup mailbox in the APU hardware.
> 
> Then you need #mbox-cells here.
> 
> And in that case, what makes it a syscon?
> 
The apu_mbox are registers for setup mail box communications between apu
processor and the AP side kernel drivers. It also has spare registers
that reserved for keep specific information between apu and AP side.
That's why I set it as syscon to avoid ioremap from users. Do you think
it is reasonable or it is better to be kept inside the user nodes when
using it?

> >
> > > > +        compatible = "mediatek,mt8192-apu_mbox", "syscon";
> > > > +        reg = <0x19000000 0x1000>;
> > > > +    };