On 01/09/2017 09:56 PM, Marek Vasut wrote:
> 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 ?
Only if you call of_register_spi_devices().
We for example have devices that can either work in SPI or I2C mode and both
use the same compatible string. Depending on whether the device is a subnode
of a SPI or I2S controller it is registered as a SPI or I2C device.
This situation is not that different.
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