linux-kernel - Re: [RFC PATCH 6/7] dt-bindings: motion: Add adi,tmc5240 bindings

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Message-ID: <7b2a8d71-9d83-4d40-903b-ba7ef1c686f3@baylibre.com>
Date: Fri, 28 Feb 2025 16:38:51 -0600
From: David Lechner <dlechner@...libre.com>
To: David Jander <david@...tonic.nl>, linux-kernel@...r.kernel.org
Cc: linux-iio@...r.kernel.org, Jonathan Corbet <corbet@....net>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
 linux-doc@...r.kernel.org, Nuno Sa <nuno.sa@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Oleksij Rempel <o.rempel@...gutronix.de>
Subject: Re: [RFC PATCH 6/7] dt-bindings: motion: Add adi,tmc5240 bindings

On 2/27/25 10:28 AM, David Jander wrote:
> Add device-tree bindings for Analog Devices TMC5240 stepper controllers.
> 
> Signed-off-by: David Jander <david@...tonic.nl>
> ---
>  .../bindings/motion/adi,tmc5240.yaml          | 60 +++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/motion/adi,tmc5240.yaml
> 
> diff --git a/Documentation/devicetree/bindings/motion/adi,tmc5240.yaml b/Documentation/devicetree/bindings/motion/adi,tmc5240.yaml
> new file mode 100644
> index 000000000000..3364f9dfccb1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/motion/adi,tmc5240.yaml
> @@ -0,0 +1,60 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/motion/adi,tmc5240.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices TMC5240 Stepper Motor controller
> +
> +maintainers:
> +  - David Jander <david@...tonic>
> +
> +description: |
> +   Stepper motor controller with motion engine and SPI interface.

Please include a link to the datasheet.

> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,tmc5240
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1

I assume that this is the overvoltage output (OV pin). Would be nice to have
a description here saying that. There are also NAO and DIAG0/1 output pins, so
it's a bit ambiguous otherwise.

> +
> +  enable-supply:
> +    description: Optional external enable supply to control SLEEPn pin. Can
> +      be shared between several controllers.
> +

This doesn't look like a supply, but krzk already discussed that. But there
should be actual power supplies: vs-supply, vdd1v8-supply, vcc-io-supply. And
a reference voltage supply: iref-supply

And if there are any pins would make sense to connect to a gpio, we can add
those even if the driver doesn't use it currently.

> +  clocks:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +  - $ref: /schemas/motion/common.yaml#

If we need to know about what is connected to the output of a motor controller
I would expect it to be done with child node for each output. That way each
output can be unique, if needed. Basically, similar to iio/adc.yaml is used to
provide common properties for channel@ child nodes on iio devices.

> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        motor@0 {

motor-controller@ or actuator-controller@

The chip is the controller/driver, it is not a motor.

> +            compatible = "adi,tmc5240";
> +            reg = <0>;
> +            interrupts-extended = <&gpiok 7 0>;
> +            clocks = <&clock_tmc5240>;
> +            enable-supply = <&stpsleepn>;
> +            spi-max-frequency = <1000000>;
> +        };
> +    };
> +