Re: [PATCH 1/2] dt-bindings: iio: frequency: Add ADF4382

Conor Dooley
2024-11-14T19:55:57Z

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On Thu, Nov 14, 2024 at 03:03:10PM +0200, Ciprian Hegbeli wrote:
> The ADF4382A is a high performance, ultralow jitter, Frac-N PLL
> with integrated VCO ideally suited for LO generation for 5G applications
> or data converter clock applications. The high performance
> PLL has a figure of merit of -239 dBc/Hz, low 1/f Noise and
> high PFD frequency of 625MHz in integer mode that can achieve
> ultralow in-band noise and integrated jitter. The ADF4382A can
> generate frequencies in a fundamental octave range of 11.5 GHz to
> 21 GHz, thereby eliminating the need for sub-harmonic filters. The
> divide by 2 and 4 output dividers on the part allow frequencies to
> be generated from 5.75GHz to 10.5GHz and 2.875GHz to 5.25GHz
> respectively.
>
> Signed-off-by: Ciprian Hegbeli <ciprian.hegbeli@analog.com>
> ---
> .../bindings/iio/frequency/adi,adf4382.yaml | 141 ++++++++++++++++++
> 1 file changed, 141 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/frequency/adi,adf4382.yaml
>
> diff --git a/Documentation/devicetree/bindings/iio/frequency/adi,adf4382.yaml b/Documentation/devicetree/bindings/iio/frequency/adi,adf4382.yaml
> new file mode 100644
> index 000000000000..44a29ac7a2e8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/frequency/adi,adf4382.yaml
> @@ -0,0 +1,141 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/frequency/adi,adf4382.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: ADF4382 Microwave Wideband Synthesizer with Integrated VCO
> +
> +maintainers:
> + - Antoniu Miclaus <antoniu.miclaus@analog.com>
> + - Ciprian Hegbeli <ciprian.hegbeli@analog.com>
> +
> +description: The ADF4382 is a high performance, ultralow jitter, Frac-N PLL with
> + integrated VCO ideally suited for LO generation for 5G applications
> + or data converter clock applications.
> +
> + https://www.analog.com/en/products/adf4382a.html
> +
> +properties:
> + compatible:
> + enum:
> + - adi,adf4382
> + - adi,adf4382a
> +
> + reg:
> + maxItems: 1
> +
> + spi-max-frequency:
> + maximum: 75000000
> +
> + clocks:
> + description: Clock to provide CLKIN reference clock signal.
> + maxItems: 1

All you need here is:

clocks:
items:
- description: foo

> +
> + clock-names:
> + description:
> + External clock that provides reference input frequency.

Drop the description, you have one above.

> + items:
> + - const: ref_clk
> +
> + '#clock-cells':
> + const: 0
> +
> + clock-output-names:
> + maxItems: 1
> +
> + adi,charge-pump-microamp:
> + description:
> + The charge pump current that the external loop filter was designed for.
> + If this property is not specified, then the charge pump current is set to the
> + default 11100uA. The valid values are listed below. However, if the set value is
> + not supported, the driver will look for the closest valid charge pump current.
> + anyOf:
> + - enum: [790, 990, 1190, 1380, 1590, 1980, 2390, 2790, 3180, 3970, 4770, 5570, 6330, 7910, 9510, 11100]

Just enum, drop the anyof.

> +
> + adi,ref-divider:
> + description:
> + Input divider of the reference frequency, cannot be lower then 1 or
> + higher then 63.
> + allOf:

This allof isn't required, all these can move up a level. Not entirely
sure why this is actually required though, shouldn't the driver be able
to compute this based on the output frequency requested?

> + - $ref: /schemas/types.yaml#/definitions/uint32
> + - minimum: 1
> + - maximum: 63
> + - default: 1

> + maxItems: 1

drop this.

> +
> + adi,ref-doubler-enable:
> + description:
> + Enables the doubling of the reference clock.
> + type: boolean

type: flag
but same question here about why this is in the binding.

> + maxItems: 1
> +
> + adi,bleed-word:
> + description:
> + A small programmable constant charge pump current, known as bleed current,
> + can be used to optimize the phase noise and fractional spurious signals
> + in fractional mode.
> + allOf:
> + - $ref: /schemas/types.yaml#/definitions/uint32
> + - minimum: 0
> + - maximum: 4095
> + - default: 0
> + maxItems: 1

Same comments about allOf/maxItems here. Additionally, why is this in
the binding, and not something controllable from userspace etc?
If it stays in the binding, why "bleed-word" and not
"bleed-current-microamps" (or w/e other unit that is more appropriate)

> +
> + adi,power-up-frequency:
> + description:
> + PLL tunes to the set frequency on probe or defaults to 2,305 GHz.
> + allOf:
> + - $ref: /schemas/types.yaml#/definitions/uint64
> + - minimum: 687500000
> + - maximum: 22000000000
> + - default: 2305000000
> + maxItems: 1

Same comments here.

> +
> + adi,output-power-value:
> + description:
> + The output power amplitude level which will be applied for both channels
> + at startup.
> + allOf:
> + - $ref: /schemas/types.yaml#/definitions/uint32
> + - minimum: 0
> + - maximum: 15
> + - default: 11
> + maxItems: 1

Is this a unitless gain or a power that should have a unit?
Same comments as other properties about allOf/anyOf.

> +
> + adi,spi-3wire-enable:

spi-3wire is a standard property

> + description:
> + Uses SPI in 3 wire mode, by default is uses 4 wire mode.
> + type: boolean
> + maxItems: 1
> +
> + adi,cmos-3v3:
> + description:
> + Sets the SPI logic to 3.3V, by defautl it uses 1,8V.
> + type: boolean
> + maxItems: 1

type: flag. Drop the maxItems.

Cheers,
Conor.

> +
> +required:
> + - compatible
> + - reg
> + - clocks
> + - clock-names
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + spi {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + frequency@0 {
> + compatible = "adi,adf4382";
> + reg = <0>;
> + spi-max-frequency = <1000000>;
> + clocks = <&adf4382_clkin>;
> + clock-names = "ref_clk";
> + adi,charge-pump-current = <15>;
> + adi,ref-divider = <1>;
> + };
> + };
> +...
> --
> 2.43.0
>

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