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

Cosmin Tanislav
2022-10-17T06:55:08Z

On 10/17/22 04:59, Krzysztof Kozlowski wrote:
> 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?
>
This node is needed for active analog temperature sensors.
It has fewer options than the thermocouple, as it only supports
a table to map from voltage to temperature and specifying whether
the measurement is differential or single-ended.

If you did as much as glimpsed at the datasheet you would have
understood.

>> + 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.
>

That's how the rest of the file is written.

>
>
>> + 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.
>

That's how the rest of the file is written.

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

That's how the rest of the file is written.

The chip uses mv-K, but the binding specifies nv-uK, the driver
translates it into the appropriate unit.

>
>> + 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.
>

It's pretty obvious that "Table" in a binding refers to the datasheet.
But if you meant datasheet, not binding, you're looking at the wrong
datasheet then.
Also, that's how the rest of the file is written.

>> + 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?
>

You're really clueless, I'll let you figure it out on your own.
Also, that's how the rest of the file is written.

>> + $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
>

That's how the rest of the file is written.
If you really want to use something different, you can submit a
patch later and fix the whole binding however you want.

>> +
>> + 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
>