On Sun, 16 May 2021 00:43:13 -0400 Liam Beguin <liambeguin@xxxxxxxxx> wrote: > Add a devicetree binding to optionally force a different IIO channel > type. > > This is useful in cases where ADC channels are connected to a circuit > that represent another unit such as a temperature or a current. > > `channel-types` was chosen instead of `io-channel-types` as this is not > part of the iio consumer bindings. > > In the current form, this patch does what it's intended to do: > change the unit displayed by `sensors`, but feels like the wrong way to > address the problem. > > Would it be possible to force the type of different IIO channels for > this kind of use case with a devicetree binding from the IIO subsystem? > > It would be convenient to do it within the IIO subsystem to have the > right unit there too. > > Thanks for your time, > Liam Hi Liam, +CC Peter for AFE part. It's an interesting approach, but I would suggest we think about this a different way. Whenever a channel is being used to measure something 'different' from what it actually measures (e.g. a voltage ADC measuring a current) that reflects their being some analog component involved. If you look at drivers/iio/afe/iio-rescale.c you can see the approach we currently use to handle this. Effectively what you add to devicetree is a consumer of the ADC channel which in turn provides services to other devices. For this current case it would be either a current-sense-amplifier or a current-sense-shunt depending on what the analog front end looks like. We have to describe the characteristics of that front end which isn't something that can be done via a simple channel type. That afe consumer device can then provide services to another consumer (e.g. iio-hwmon) which work for your usecase. The main limitation of this approach currently is you end up with one device per channel. That could be improved upon if you have a usecase where it matters. I don't think we currently have an equivalent for temperature sensing but it would be easy enough to do something similar. Jonathan > > Liam Beguin (2): > hwmon: (iio_hwmon) optionally force iio channel type > dt-bindings: hwmon: add iio-hwmon bindings > > .../devicetree/bindings/hwmon/iio-hwmon.yaml | 41 +++++++++++++++++++ > drivers/hwmon/iio_hwmon.c | 2 + > 2 files changed, 43 insertions(+) > create mode 100644 Documentation/devicetree/bindings/hwmon/iio-hwmon.yaml > > > base-commit: 9f4ad9e425a1d3b6a34617b8ea226d56a119a717
