Re: [PATCH v2 0/2] iio: add unit converter

[Andrew F. Davis]

On 04/03/2018 10:36 AM, Peter Rosin wrote:
> Hi!
> 
> This driver implements support for voltage dividers and current
> sense circuits. It's pretty generic and should be easily adaptable
> to other linear scaling purposes...
> 

I really like this idea, defining channel scaling / channel type
conversion in DT will be very useful. So much so that I would recommend
this not be a use specific driver but instead moved into the IIO core.

This would allow defining these channel conversions in the device node
itself, so as to not need a separate node just for the converter (the
conversion is not a device and probably should not have it's own node
anyway). It would also help with enabling this support for buffered
readers/writers and not just devices only supporting _raw reads/writes.

Andrew

> The driver is still named "unit converter", because it was not
> clear to me that there was a real problem with the driver being
> named that. I got the impression that the naming discussion in
> v1 was mainly about the category, and that it kind of looked odd
> and non-specific with unit-converter in the DT bindings, but
> what do I know?
> 
> Cheers,
> Peter
> 
> Changes since v1:    https://lkml.org/lkml/2018/3/19/801
> - Put the driver in the new afe category (Analog Front Ends) and do not
>   move the iio-mux driver.
> - Do not refer to the source channel as "parent", use "source" instead.
> - Have the DT compatible drive the target unit, instead of relying on a
>   "type" DT-property for that.
> - In the DT bindings, use an unnamed source channel.
> - Do not set up writes to _RAW (sorry Phil) as I don't need it and have
>   not tested it. It's easy to add back if needed.
> - Fail if the source channel does not support _RAW or _SCALE.
> - Fix various spelling issues.
> - Fix various code style issues.
> 
> Peter Rosin (2):
>   dt-bindings: iio: afe: add current-sense-cuicuit and voltage-divider
>   iio: afe: unit-converter: new driver
> 
>  .../bindings/iio/afe/current-sense-circuit.txt     |  45 ++++
>  .../bindings/iio/afe/voltage-divider.txt           |  45 ++++
>  MAINTAINERS                                        |   8 +
>  drivers/iio/Kconfig                                |   1 +
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/afe/Kconfig                            |  18 ++
>  drivers/iio/afe/Makefile                           |   6 +
>  drivers/iio/afe/iio-unit-converter.c               | 257 +++++++++++++++++++++
>  8 files changed, 381 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt
>  create mode 100644 Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
>  create mode 100644 drivers/iio/afe/Kconfig
>  create mode 100644 drivers/iio/afe/Makefile
>  create mode 100644 drivers/iio/afe/iio-unit-converter.c
>