linux-kernel - Re: [PATCH v3 08/10] dt-bindings: iio: adc: ad7476: Add ROHM bd79105

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Message-ID: <c236bb5e-dd46-4caa-81b1-9af1550feef3@gmail.com>
Date: Mon, 11 Aug 2025 11:05:42 +0300
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
 Lars-Peter Clausen <lars@...afoo.de>,
 Michael Hennerich <Michael.Hennerich@...log.com>,
 David Lechner <dlechner@...libre.com>, Nuno Sá
 <nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Liam Girdwood <lgirdwood@...il.com>,
 Mark Brown <broonie@...nel.org>, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 08/10] dt-bindings: iio: adc: ad7476: Add ROHM bd79105

On 09/08/2025 22:21, Jonathan Cameron wrote:
> On Fri, 8 Aug 2025 11:54:25 +0300
> Matti Vaittinen <mazziesaccount@...il.com> wrote:
> 
>> The ROHM BD79105 is a simple, 16-bit, 1-channel ADC with a 'CONVSTART'
>> pin used to start the ADC conversion. Other than the 'CONVSTART', there
>> are 3 supply pins (one used as a reference), analog inputs, ground and
>> communication pins. It's worth noting that the pin somewhat confusingly
>> labeled as 'DIN', is a pin which should be used as a chip-select. The IC
>> does not have any writable registers.
>>
>> The device is designed so that the output pin can, in addition to
>> outputting the data, be used as a 'data-ready'-IRQ. This, however, would
>> require the IRQ to be masked from host side for the duration of the data
>> reads - and it wouldn't also work when the SPI is shared. (As access to
>> the other SPI devices would cause data line changes to be detected as
>> IRQs - and the BD79105 provides no means to detect if it has generated
>> an IRQ).
>>
>> Hence the device-tree does not contain any IRQ properties.
> 
> Commit message needs an update as it now allows for IRQ properties.

Ah, true. Thanks :)

> 
>>
>> Add a compatible for the bd79105.
>>
>> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
>>
>> ---
>> Revision history:
>>   v2 => :
>>   - No changes
>>
>>   v1 => v2:
>>   - BD79105 can provide data-ready IRQ (or GPIO) via DOUT-pin.
>> ---
>>   .../bindings/iio/adc/adi,ad7476.yaml          | 54 +++++++++++++++++++
>>   1 file changed, 54 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
>> index d0cb32f136e5..c411a7467651 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
>> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
>> @@ -41,6 +41,7 @@ properties:
>>                 - adi,ad7910
>>                 - adi,ad7920
>>                 - adi,ad7940
>> +              - rohm,bd79105
>>                 - ti,adc081s
>>                 - ti,adc101s
>>                 - ti,adc121s
>> @@ -55,6 +56,11 @@ properties:
>>     reg:
>>       maxItems: 1
>>   
>> +  interrupts:
>> +    description:
>> +      The data-ready interrupt. Provided via DOUT pin.
>> +    maxItems: 1
>> +
>>     vcc-supply:
>>       description:
>>         Main powersupply voltage for the chips, sometimes referred to as VDD on
>> @@ -75,6 +81,10 @@ properties:
>>       description: A GPIO used to trigger the start of a conversion
>>       maxItems: 1
>>   
>> +  rdy-gpios:
>> +    description: A GPIO for detecting the data-ready.
>> +    maxItems: 1
>> +
>>   required:
>>     - compatible
>>     - reg
>> @@ -82,6 +92,20 @@ required:
>>   allOf:
>>     - $ref: /schemas/spi/spi-peripheral-props.yaml#
>>   
>> +# Devices with an IRQ
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            enum:
>> +              - rohm,bd79105
>> +    then:
>> +      properties:
>> +        interrupts: true
> 
> It's been a while since I wrote one of these, but do we need
> the true bit given we have already specified the interrupts
> property.  I think we only need to do the setting to false
> on an if: not:

I think you're right. I just used same approach that had already been 
used throughout this binding. I'll try dropping the 'true'-branches, but 
then also the other 'true'-branches should be dropped from the binding.

I'll just do that and send v4. Let's see what Rob/Krzk/Conor have to say :)

Yours,
	-- Matti