Re: [PATCH v6 4/6] dt-bindings: iio: Add adis16550 bindings

["Nuno Sá" <noname.nuno@gmail.com>]

On Tue, 2025-02-04 at 19:25 +0000, Conor Dooley wrote:
> On Tue, Feb 04, 2025 at 04:36:08PM +0200, Robert Budai wrote:
> > Document the ADIS16550 device devicetree bindings.
> > 
> > Co-developed-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> > Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> > Signed-off-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
> > Signed-off-by: Robert Budai <robert.budai@analog.com>
> > ---
> > 
> > v6:
> > - applied blank line suggestions
> > - added clock-frequency dependency change suggestions
> > - yamllint corrections
> > 
> >  .../bindings/iio/imu/adi,adis16550.yaml       | 83 +++++++++++++++++++
> >  MAINTAINERS                                   |  9 ++
> >  2 files changed, 92 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/iio/imu/adi,adis16550.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/imu/adi,adis16550.yaml
> > b/Documentation/devicetree/bindings/iio/imu/adi,adis16550.yaml
> > new file mode 100644
> > index 000000000000..8750bb937979
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/imu/adi,adis16550.yaml
> > @@ -0,0 +1,83 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/iio/imu/adi,adis16550.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices ADIS16550 and similar IMUs
> > +
> > +maintainers:
> > +  - Nuno Sa <nuno.sa@analog.com>
> > +  - Ramona Gradinariu <ramona.gradinariu@analog.com>
> > +  - Antoniu Miclaus <antoniu.miclaus@analog.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - adi,adis16550
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  spi-cpha: true
> > +  spi-cpol: true
> > +
> > +  spi-max-frequency:
> > +    maximum: 15000000
> > +
> > +  vdd-supply: true
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  reset-gpios:
> > +    description:
> > +      Must be the device tree identifier of the RESET pin. If specified,
> > +      it will be asserted during driver probe. As the line is active low,
> > +      it should be marked GPIO_ACTIVE_LOW.
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    description: If not provided, then the internal clock is used.
> > +    maxItems: 1
> > +
> > +  clock-frequency:
> > +    description: Clock frequency in Hz when an external clock is used.
> > +    oneOf:
> > +      - minimum: 1
> > +        maximum: 128
> > +      - minimum: 3000
> > +        maximum: 4500
> 
> I don't get why this is a property, to be honest. When you've got an
> external clock, why isn't the frequency obtained from the clock provider
> node?
> 

The main purpose of this property is actually to show/document the constrains of
the external clock. We can very well just error out in the driver (and we do
that) and not have this property. I mentioned this property to Robert some
revisions ago and I also pointed out that I wasn't really sure if it should be
used or not (I guess this is more for fixed clock providers...). IIRC, I did
asked for some advice/comments but we got none so I assume Robert just decided
to use it and see what you guys had to say about it.

- Nuno Sá

> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - interrupts
> > +  - spi-cpha
> > +  - spi-cpol
> > +  - spi-max-frequency
> > +  - vdd-supply
> > +
> > +dependentRequired:
> > +  clock: [clock-frequency]
>          ^
> typo, missing s.
> 
> > +
> > +allOf:
> > +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> > +additionalProperties: false
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +        imu@0 {
> > +            compatible = "adi,adis16550";
> > +            reg = <0>;
> > +            spi-max-frequency = <15000000>;
> > +            spi-cpol;
> > +            spi-cpha;
> > +            vdd-supply = <&vdd>;
> > +            interrupts = <4 IRQ_TYPE_EDGE_FALLING>;
> > +            interrupt-parent = <&gpio>;
> > +        };
> > +    };
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 6247500cf427..8913e13dcaef 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -1452,6 +1452,15 @@
> > W:	https://ez.analog.com/linux-software-drivers
> >  F:	Documentation/devicetree/bindings/iio/imu/adi,adis16475.yaml
> >  F:	drivers/iio/imu/adis16475.c
> >  
> > +ANALOG DEVICES INC ADIS16550 DRIVER
> > +M:	Nuno Sa <nuno.sa@analog.com>
> > +M:	Ramona Gradinariu <ramona.gradinariu@analog.com>
> > +M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
> > +L:	linux-iio@vger.kernel.org
> > +S:	Supported
> > +W:	https://ez.analog.com/linux-software-drivers
> > +F:	Documentation/devicetree/bindings/iio/imu/adi,adis16550.yaml
> > +
> >  ANALOG DEVICES INC ADM1177 DRIVER
> >  M:	Michael Hennerich <Michael.Hennerich@analog.com>
> >  L:	linux-hwmon@vger.kernel.org
> > -- 
> > 2.39.5
> >