On 01/09/2017 09:07 PM, Lars-Peter Clausen wrote:
> On 01/09/2017 02:47 PM, Marek Vasut wrote:
>> On 01/09/2017 02:45 PM, Lars-Peter Clausen wrote:
>>> On 01/09/2017 01:03 AM, Marek Vasut wrote:
>>> [...]
>>>> +- renesas,gyroadc-mode: GyroADC mode of operation, must be either of:
>>>> + 1 - MB88101A mode, 12bit sampling, 4 channels
>>>> + 2 - ADCS7476 mode, 15bit sampling, 8 channels
>>>> + 3 - MAX1162 mode, 16bit sampling, 8 channels
>>>
>>> So is this a ADC, or is this just a specialized SPI controller that
>>> interfaces to an external ADC?
>>
>> It's a special SPI controller, except one cannot access the SPI bus
>> directly. It sends out clock and reads in the data from the ADC .
>
> OK, thanks for the clarification. The commit message does not mention this
> at the moment and makes it sound like this is a built-in ADC.
>
> Also the renesas,gyroadc-mode property is more of a driver configuration
> setting rather than a description of the hardware, at least it is not very
> DT-ish.
>
> I'd go with something like
>
>
> &adc {
> compatible = "renesas,r8a7791-gyroadc";
> ...
>
> adc@0 {
> reg = <0>;
> compatible = "maxim,max1162";
But then the max1162 ADC driver* will try to bind to this, right ?
And since the MAX1162 is an SPI device, it will fail to work as the
ADC driver does not provide any sort of SPI interface. Or is that
actually OK ?
* I dunno if that made it mainline yet, but there's a driver for
compatible ADC, https://patchwork.kernel.org/patch/9472237/
> ref-supply = <&vref_max1162>;
> };
>
> ... repeat for each front-end ADC.
>
> };
>
> That's much more idiomatic which makes it e.g. easier to understand for
> someone who does not know the specifics of the binding.
>
> It also makes it more extensible and portable in terms of the same binding
> for similar devices.
>
> Internally in the driver you can still use your mode variable initializing
> it based on the compatible string of the subnode.
>
> - Lars
>
--
Best regards,
Marek Vasut
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