linux-kernel - Re: [PATCH v3 2/4] dt-bindings: watchdog: add new binding for meson secure watchdog

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Date:   Wed, 30 Oct 2019 08:41:26 -0500
From:   Rob Herring <robh@...nel.org>
To:     Xingyu Chen <xingyu.chen@...ogic.com>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Kevin Hilman <khilman@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Qianggui Song <qianggui.song@...ogic.com>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        Jian Hu <jian.hu@...ogic.com>,
        LINUX-WATCHDOG <linux-watchdog@...r.kernel.org>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 2/4] dt-bindings: watchdog: add new binding for meson
 secure watchdog

On Wed, Oct 30, 2019 at 7:59 AM Xingyu Chen <xingyu.chen@...ogic.com> wrote:
>
> Hi,Rob
>
> On 2019/10/30 4:51, Rob Herring wrote:
> > On Mon, Oct 28, 2019 at 3:35 AM Xingyu Chen <xingyu.chen@...ogic.com> wrote:
> >>
> >> Hi, Rob
> >>
> >> On 2019/10/26 4:30, Rob Herring wrote:
> >>> On Fri, Oct 25, 2019 at 02:13:02PM +0800, Xingyu Chen wrote:
> >>>> The binding targets the Meson-A/C series compatible SoCs, in which the
> >>>> watchdog registers are in secure world.
> >>>>
> >>>> Signed-off-by: Xingyu Chen <xingyu.chen@...ogic.com>
> >>>> ---
> >>>>    .../bindings/watchdog/amlogic,meson-sec-wdt.yaml   | 34 ++++++++++++++++++++++
> >>>>    1 file changed, 34 insertions(+)
> >>>>    create mode 100644 Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml
> >>>>
> >>>> diff --git a/Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml b/Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml
> >>>> new file mode 100644
> >>>> index 00000000..0bbc807
> >>>> --- /dev/null
> >>>> +++ b/Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml
> >>>> @@ -0,0 +1,34 @@
> >>>> +# SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> >>>> +# Copyright (c) 2019 Amlogic, Inc
> >>>> +%YAML 1.2
> >>>> +---
> >>>> +$id: "http://devicetree.org/schemas/power/amlogic,meson-sec-wdt.yaml#"
> >>>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> >>>> +
> >>>> +title: Amlogic Meson Secure Watchdog Timer
> >>>> +
> >>>> +maintainers:
> >>>> +  - Xingyu Chen <xingyu.chen@...ogic.com>
> >>>> +
> >>>> +description: |+
> >>>> +  Secure Watchdog Timer used in Meson-A/C series Compatible SoCs
> >>>> +
> >>>> +properties:
> >>>> +  compatible:
> >>>> +    enum:
> >>>> +      - amlogic,meson-sec-wdt
> >>>
> >>> If there are no other properties, then you don't need this. Just have
> >>> the secure firmware driver instantiate the watchdog.
> >> I'am very sorry i don't understand how to initialize the watchdog driver
> >> if the compatible property is removed, Could you give me more
> >> suggestions or examples ？ Thank you very much.
> >
> > platform_device_register_simple() from the secure firmware driver.
> Thanks for your help. The device node of wdt looks useless if I use this
> function to register device. if so, how should I get the pointer to
> secure-monitor in wdt driver ? or should I use directly arm_smccc to
> access the secfw ?

You can use of_find_compatible_node(). There should only be one firmware node.

Rob