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From:   Rob Herring <robh@kernel.org>
Date:   Wed, 31 Aug 2022 17:05:10 -0500
Message-ID: <CAL_JsqKD33Bxoi88WAEECH9rn4AZjijXRoZemptirc-Ogs7-6w@mail.gmail.com>
Subject: Re: [RFC PATCH v2 1/4] dt-bindings: net: can: add STM32 bxcan DT bindings
To:     Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Amarula patchwork <linux-amarula@amarulasolutions.com>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        Michael Trimarchi <michael@amarulasolutions.com>,
        Dario Binacchi <dariobin@libero.it>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Wolfgang Grandegger <wg@grandegger.com>,
        devicetree@vger.kernel.org,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-can@vger.kernel.org,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-stm32@st-md-mailman.stormreply.com>,
        netdev <netdev@vger.kernel.org>
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On Fri, Aug 26, 2022 at 2:27 AM Dario Binacchi
<dario.binacchi@amarulasolutions.com> wrote:
>
> Hi Rob,
>
> On Thu, Aug 25, 2022 at 11:12 PM Rob Herring <robh@kernel.org> wrote:
> >
> > On Sat, Aug 20, 2022 at 10:29:33AM +0200, Dario Binacchi wrote:
> > > Add documentation of device tree bindings for the STM32 basic extended
> > > CAN (bxcan) controller.
> > >
> > > Signed-off-by: Dario Binacchi <dariobin@libero.it>
> > > Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> > >
> > > ---
> > >
> > > Changes in v2:
> > > - Change the file name into 'st,stm32-bxcan-core.yaml'.
> > > - Rename compatibles:
> > >   - st,stm32-bxcan-core -> st,stm32f4-bxcan-core
> > >   - st,stm32-bxcan -> st,stm32f4-bxcan
> > > - Rename master property to st,can-master.
> > > - Remove the status property from the example.
> > > - Put the node child properties as required.
> > >
> > >  .../bindings/net/can/st,stm32-bxcan.yaml      | 136 ++++++++++++++++++
> > >  1 file changed, 136 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml b/Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml
> > > new file mode 100644
> > > index 000000000000..288631b5556d
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml
> > > @@ -0,0 +1,136 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/net/can/st,stm32-bxcan.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: STMicroelectronics bxCAN controller
> > > +
> > > +description: STMicroelectronics BxCAN controller for CAN bus
> > > +
> > > +maintainers:
> > > +  - Dario Binacchi <dario.binacchi@amarulasolutions.com>
> > > +
> > > +allOf:
> > > +  - $ref: can-controller.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - st,stm32f4-bxcan-core
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  resets:
> > > +    maxItems: 1
> > > +
> > > +  clocks:
> > > +    description:
> > > +      Input clock for registers access
> > > +    maxItems: 1
> > > +
> > > +  '#address-cells':
> > > +    const: 1
> > > +
> > > +  '#size-cells':
> > > +    const: 0
> > > +
> > > +additionalProperties: false
> > > +
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - resets
> > > +  - clocks
> > > +  - '#address-cells'
> > > +  - '#size-cells'
> > > +
> > > +patternProperties:
> > > +  "^can@[0-9]+$":
> > > +    type: object
> > > +    description:
> > > +      A CAN block node contains two subnodes, representing each one a CAN
> > > +      instance available on the machine.
> > > +
> > > +    properties:
> > > +      compatible:
> > > +        enum:
> > > +          - st,stm32f4-bxcan
> > > +
> > > +      st,can-master:
> > > +        description:
> > > +          Master and slave mode of the bxCAN peripheral is only relevant
> > > +          if the chip has two CAN peripherals. In that case they share
> > > +          some of the required logic, and that means you cannot use the
> > > +          slave CAN without the master CAN.
> > > +        type: boolean
> > > +
> > > +      reg:
> > > +        description: |
> > > +          Offset of CAN instance in CAN block. Valid values are:
> > > +            - 0x0:   CAN1
> > > +            - 0x400: CAN2
> > > +        maxItems: 1
> > > +
> > > +      interrupts:
> > > +        items:
> > > +          - description: transmit interrupt
> > > +          - description: FIFO 0 receive interrupt
> > > +          - description: FIFO 1 receive interrupt
> > > +          - description: status change error interrupt
> > > +
> > > +      interrupt-names:
> > > +        items:
> > > +          - const: tx
> > > +          - const: rx0
> > > +          - const: rx1
> > > +          - const: sce
> > > +
> > > +      resets:
> > > +        maxItems: 1
> > > +
> > > +      clocks:
> > > +        description:
> > > +          Input clock for registers access
> > > +        maxItems: 1
> > > +
> > > +    additionalProperties: false
> > > +
> > > +    required:
> > > +      - compatible
> > > +      - reg
> > > +      - interrupts
> > > +      - resets
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/clock/stm32fx-clock.h>
> > > +    #include <dt-bindings/mfd/stm32f4-rcc.h>
> > > +
> > > +    can: can@40006400 {
> > > +        compatible = "st,stm32f4-bxcan-core";
> > > +        reg = <0x40006400 0x800>;
> > > +        resets = <&rcc STM32F4_APB1_RESET(CAN1)>;
> > > +        clocks = <&rcc 0 STM32F4_APB1_CLOCK(CAN1)>;
> > > +        #address-cells = <1>;
> > > +        #size-cells = <0>;
> > > +
> >
> > Missing 'ranges'.
>
> In the file arch/arm/boot/dts/stm32f429.dtsi, I didn't find any other
> node using the 'ranges' property, so
> I didn't use it for the CAN node either.

If the child node is a memory mapped address, then you need 'ranges'.
Otherwise, things like of_iomap() don't work.

Looking at the above file, only efuse@1fff7800 and adc@40012000 seem
to be cases also missing 'ranges'.

Rob