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

Krzysztof Kozlowski
2022-10-17T02:00:05Z

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