This series extends the ds4424 IIO DAC driver and its devicetree binding
to support the DS4402 and DS4404 current DAC variants.

DS440x devices share the same register map as DS442x but use a different
resolution (5-bit vs 7-bit) and a different full-scale current formula.
The full-scale current depends on external Rfs resistors connected to
the FS pins, so a new optional DT property is added to provide the
per-channel Rfs values and allow the driver to report a correct IIO
SCALE (mA/step).

While adding DS440x support, a few related issues were addressed:
- Port to regmap
- Reject -128 in RAW writes on DS442x, which cannot be represented with
  sign-magnitude encoding and could silently program an unintended
  output.
- Preserve preconfigured values on probe.
- Ratelimit read error logging and use device context.

Oleksij Rempel (8):
  dt-bindings: iio: dac: maxim,ds4424: add ds4402/ds4404
  dt-bindings: iio: dac: maxim,ds4424: add maxim,rfs-ohms property
  iio: dac: ds4424: add DS4402/DS4404 device IDs
  iio: dac: ds4424: sort headers alphabetically
  iio: dac: ds4424: convert to regmap
  iio: dac: ds4424: fix -128 rejection and refactor raw access
  iio: dac: ds4424: add Rfs-based scale and per-variant limits
  iio: dac: ds4424: ratelimit read errors and use device context

 .../bindings/iio/dac/maxim,ds4424.yaml        |  43 ++-
 drivers/iio/dac/Kconfig                       |   1 +
 drivers/iio/dac/ds4424.c                      | 351 ++++++++++++------
 3 files changed, 286 insertions(+), 109 deletions(-)

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2.47.3