Hi,
On Thursday 24 of January 2013 19:19:57 Lars-Peter Clausen wrote:
> On 01/24/2013 05:12 PM, Doug Anderson wrote:
> > Lars,
> >
> > Thank you for your comments / thoughts...
>
> Hi,
>
> > On Thu, Jan 24, 2013 at 1:54 AM, Lars-Peter Clausen <lars@xxxxxxxxxx>
wrote:
> >> adc: adc@12D10000 {
> >>
> >> #io-channel-cells = <1>;
> >> io-channel-output-names = "adc1", "adc2", ...;
> >>
> >> ncp15wb473@0 {
> >>
> >> compatible = "ntc,ncp15wb473";
> >> ...
> >> io-channels = <&adc 0>; // First ADC channel
> >
> > I'm not an expert, but I think the typical way is:
> > * No need to include a handle to &adc. It's logically our parent. In
> > a similar way i2c devices don't specify their parent bus--they are
> > just listed under it.
> > * The "0" should be specified with reg = <0>
>
> The relationship between the IIO sensor device and the consumer device
> is not always a parent child relationship. In this case it makes sense
> to have the ADC as the parent for the thermistors. But for other cases
> this may not be true. E.g. take a touchscreen or power monitoring
> platform device which uses the IIO device to do measurements.
The policy is to use children with reg property only inside a node
representing a bus controller through which the child device is being
accessed (like I2C, SPI).
I would see IIO bindings similar to what we have with GPIOs, interrupts or
regulators, so io-channels = <&iio-controller channel> seems fine (or
rather iio-channels) with the node under appropriate parent.
> > To implement this I'd imagine that we'll need a new API call, right?
> > In this case the thermistor driver won't know the name of the channel.
> >
> > It can find the ADC (the struct device and probably other things) and
> >
> > knows a channel index. Am I understanding properly?
>
> This can be done by adding a new api call, but it would be best if both
> dt and non-dt based consumers can use the same function. I outlined one
> possible solution how this can be done in the previous mail to Naveen.
In case of the solution I mentioned, implementation would be almost
identical to what is done with GPIOs (see drivers/gpio/gpiolib-of.c).
Best regards,
Tomasz
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