Re: [PATCH 2/4] dt-bindings: iio: adc: Add adi,ad4052

[David Lechner]

On Thu, Mar 6, 2025 at 3:04 PM Jorge Marques <jorge.marques@xxxxxxxxxx> wrote:
>
> Add dt-bindings for AD4052 family, devices AD4050/AD4052/AD4056/AD4058,
> low-power with monitor capabilities SAR ADCs.

> Contain selectable oversampling and sample rate, the latter for both
> oversampling and monitor mode.
> The monitor capability is exposed as an IIO threshold either direction
> event.

These sounds like they are describing the driver so aren't appropriate
for this commit message. Here we should only be talking about the
bindings.

>
> Signed-off-by: Jorge Marques <jorge.marques@xxxxxxxxxx>
> ---
>  .../devicetree/bindings/iio/adc/adi,ad4052.yaml    | 80 ++++++++++++++++++++++
>  MAINTAINERS                                        |  6 ++
>  2 files changed, 86 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4052.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4052.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..4602f1f0184d58f33883852ff6d76933758825f1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4052.yaml
> @@ -0,0 +1,80 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright 2025 Analog Devices Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/adi,ad4052.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD4052 ADC family device driver
> +
> +maintainers:
> +  - Jorge Marques <jorge.marques@xxxxxxxxxx>
> +
> +description: |
> +  Analog Devices AD4052 Single Channel Precision SAR ADC family
> +
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/ad4050.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/ad4052.pdf

The links above don't work for me. Instead...

https://www.analog.com/media/en/technical-documentation/data-sheets/ad4050-ad4056.pdf
https://www.analog.com/media/en/technical-documentation/data-sheets/ad4052-ad4058.pdf

> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad4050
> +      - adi,ad4052
> +      - adi,ad4056
> +      - adi,ad4058
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    description:
> +      Reference clock
> +    maxItems: 1

I don't see any pins in the datasheet about a "reference clock" input.
Is this for the CNV pin? If this is for the internal clock, then we
don't need a property for it.

> +
> +  interrupts:
> +    items:
> +      - description: threshold events.
> +      - description: device ready and data ready.
> +

Since there are multiple interrupts, we should also have an
interrupt-names property. Also, the interrupts should be named after
the pin they are connected to, not the function. So the interrupt
names should be "rdy", "gp0", and "gp1".

> +  cnv-gpios:
> +    maxItems: 1

Not necessary, but I would not mind having a description that says
that the CNV pin may also be connected to the CS line of the SPI
controller if it is not connected to a GPIO.

> +
> +  spi-max-frequency:
> +    maximum: 62500000
> +
> +  vdd-supply: true

> +  vdd_1_8-supply: true

This one seems redundant and should be dropped.

But there is also a possible separate reference voltage supply, so we
should have a ref-supply property.

> +  vio-supply: true

These chips also have GPIO pins, so we can add the gpio-controller and
#gpio-cells properties to the bindings even if we don't implement this
in the driver.

> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts

The chip won't work without vcc-supply and vio-supply so they should
be required. ref-supply is clearly optional though.



> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        adc@0 {
> +            compatible = "adi,ad4052";
> +            reg = <0>;
> +            spi-max-frequency = <25000000>;
> +
> +            interrupt-parent = <&gpio>;
> +            interrupts = <0 0 IRQ_TYPE_EDGE_RISING>,
> +                         <0 1 IRQ_TYPE_EDGE_RISING>;
> +            cnv-gpios = <&gpio 2 GPIO_ACTIVE_HIGH>;
> +        };
> +    };
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 06f122cb8bbd15a0076c229dfc89be0b5126f237..fef8adaee888d59e1aa3b3592dda5a8bea0b7677 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1317,6 +1317,12 @@ F:       Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml
>  F:     Documentation/iio/ad4030.rst
>  F:     drivers/iio/adc/ad4030.c
>
> +ANALOG DEVICES INC AD4052 DRIVER
> +M:     Jorge Marques <jorge.marques@xxxxxxxxxx>
> +S:     Supported
> +W:     https://ez.analog.com/linux-software-drivers
> +F:     Documentation/devicetree/bindings/iio/adc/adi,ad4052.yaml
> +
>  ANALOG DEVICES INC AD4130 DRIVER
>  M:     Cosmin Tanislav <cosmin.tanislav@xxxxxxxxxx>
>  L:     linux-iio@xxxxxxxxxxxxxxx
>
> --
> 2.48.1
>