[PATCH v2 0/2] iio: chemical: add support for SGP41 sensor

[Akshat Chandra <notmissinge@gmail.com>]

The SGP41 is a gas sensor used for air quality monitoring by sensing
VOC and NOx.

This driver follows the approach of exposing raw resistance values to userspace, where the gas-index algorithm can
be applied.

Temperature and relative humidity compensation are supported and can
be configured through the driver's IIO attributes.

The SGP41 is similar to the existing SGP40, but requires its own driver
for the following reasons:

- It has a dedicated conditioning command that must be performed before
  raw measurements.
- A measurement returns a 6-byte response containing two raw tick
  values, each with its own CRC, rather than the SGP40's single value.
- It supports both VOC and NOx measurements and requires the heater to
  be powered off after use.

The series consists of two patches:

  1/2: dt-bindings: iio: chemical: Add Sensirion SGP41 binding
       Add a dedicated Device Tree binding, including the VDD supply.
  2/2: iio: chemical: Add support for Sensirion SGP41
       Add the IIO driver for the sensor.

Changes in v2:
- Split the binding and driver into separate patches.
- Add a dedicated Device Tree binding documenting the VDD supply.
- Update the driver and patch descriptions following review feedback.
- Fixed some issues in driver.

v1: https://patchew.org/linux/20260831151235.64076-1-notmissinge%40gmail.com/

Signed-off-by: Akshat Chandra <notmissinge@gmail.com>