Re: [PATCH 2/3] dt-bindings: iio: temperature: ltc2983: support more parts

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 14/10/2022 08:37, Cosmin Tanislav wrote:
> From: Cosmin Tanislav <cosmin.tanislav@analog.com>
> 
> Add support for the following parts:
>  * LTC2984
>  * LTC2986
>  * LTM2985
> 
> The LTC2984 is a variant of the LTC2983 with EEPROM.
> The LTC2986 is a variant of the LTC2983 with only 10 channels,
> EEPROM and support for active analog temperature sensors.
> The LTM2985 is software-compatible with the LTC2986.
> 
> Signed-off-by: Cosmin Tanislav <cosmin.tanislav@analog.com>
> ---
>  .../bindings/iio/temperature/adi,ltc2983.yaml | 63 +++++++++++++++++--
>  1 file changed, 59 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml b/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml
> index 722781aa4697..c33ab524fb64 100644
> --- a/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml
> +++ b/Documentation/devicetree/bindings/iio/temperature/adi,ltc2983.yaml
> @@ -4,19 +4,27 @@
>  $id: http://devicetree.org/schemas/iio/temperature/adi,ltc2983.yaml#
>  $schema: http://devicetree.org/meta-schemas/core.yaml#
>  
> -title: Analog Devices LTC2983 Multi-sensor Temperature system
> +title: Analog Devices LTC2983, LTC2986, LTM2985 Multi-sensor Temperature system
>  
>  maintainers:
>    - Nuno Sá <nuno.sa@analog.com>
>  
>  description: |
> -  Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
> +  Analog Devices LTC2983, LTC2984, LTC2986, LTM2985 Multi-Sensor Digital
> +  Temperature Measurement Systems
> +
>    https://www.analog.com/media/en/technical-documentation/data-sheets/2983fc.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/2984fb.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/29861fa.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/ltm2985.pdf
>  
>  properties:
>    compatible:
>      enum:
>        - adi,ltc2983
> +      - adi,ltc2984
> +      - adi,ltc2986
> +      - adi,ltm2985
>  
>    reg:
>      maxItems: 1
> @@ -26,7 +34,7 @@ properties:
>  
>    adi,mux-delay-config-us:
>      description:
> -      The LTC2983 performs 2 or 3 internal conversion cycles per temperature
> +      The device performs 2 or 3 internal conversion cycles per temperature
>        result. Each conversion cycle is performed with different excitation and
>        input multiplexer configurations. Prior to each conversion, these
>        excitation circuits and input switch configurations are changed and an
> @@ -145,7 +153,7 @@ patternProperties:
>        adi,three-conversion-cycles:
>          description:
>            Boolean property which set's three conversion cycles removing
> -          parasitic resistance effects between the LTC2983 and the diode.
> +          parasitic resistance effects between the device and the diode.
>          type: boolean
>  
>        adi,average-on:
> @@ -353,6 +361,41 @@ patternProperties:
>          description: Boolean property which set's the adc as single-ended.
>          type: boolean
>  
> +  "^temp@":

There is already a property for thermocouple. Isn't a thermocouple a
temperature sensor? IOW, why new property is needed?

> +    type: object
> +    description:
> +      Represents a channel which is being used as an active analog temperature
> +      sensor.
> +
> +    properties:
> +      adi,sensor-type:
> +        description:
> +          Identifies the sensor as an active analog temperature sensor.
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        const: 31
> +
> +      adi,single-ended:
> +        description: Boolean property which sets the sensor as single-ended.

Drop "Boolean property which sets" - it's obvious from the type.



> +        type: boolean
> +
> +      adi,custom-temp:
> +        description:
> +          This is a table, where each entry should be a pair of

"This is a table" - obvious from the type.

> +          voltage(mv)-temperature(K). The entries must be given in nv and uK

mv-K or nv-uK? Confusing...

> +          so that, the original values must be multiplied by 1000000. For
> +          more details look at table 71 and 72.

There is no table 71 in the bindings... It seems you pasted it from
somewhere.

> +          Note should be signed, but dtc doesn't currently maintain the
> +          sign.

What do you mean? "Maintain" as allow or keep when building FDT?  What's
the problem of using negative numbers here and why it should be part of
bindings?

> +        $ref: /schemas/types.yaml#/definitions/uint64-matrix
> +        minItems: 3
> +        maxItems: 64
> +        items:
> +          minItems: 2
> +          maxItems: 2

Instead describe the items with "description" (and maybe constraints)
like here:

https://elixir.bootlin.com/linux/v5.19/source/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml#L278

> +
> +    required:
> +      - adi,custom-temp
> +
>    "^rsense@":
>      type: object
>      description:
> @@ -382,6 +425,18 @@ required:
>    - reg
>    - interrupts
>  
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - adi,ltc2983
> +              - adi,ltc2984
> +    then:
> +      patternProperties:
> +        "^temp@": false
> +
>  additionalProperties: false
>  
>  examples:

Best regards,
Krzysztof