[PATCH v4 0/2] iio: magnetometer: add support for Melexis MLX90393

[Nikhil Gautam <nikhilgtr@gmail.com>]

Hi,

This series adds initial Industrial I/O subsystem support for the
Melexis MLX90393 3-axis magnetometer and temperature sensor.

The MLX90393 supports both I2C and SPI interfaces. This series
implements support for the I2C interface while keeping the driver
structure transport-independent to simplify future SPI support.

The device uses a command-based communication protocol rather than a
conventional register-addressed interface. A small transport abstraction
layer is therefore used instead of regmap to share the common sensor
logic between the current I2C implementation and future SPI support.

Currently supported features:

* Raw magnetic field measurements for X/Y/Z axes
* Raw temperature measurements
* Configurable gain/scale selection
* Configurable oversampling ratio
* Direct mode operation through the IIO subsystem
* I2C interface support

The driver has been tested on Raspberry Pi 5 hardware using an
MLX90393 sensor connected over I2C. Magnetic field and temperature
measurements were verified through the IIO sysfs interface.

Datasheet:
https://www.melexis.com/en/documents/documentation/datasheets/datasheet-mlx90393

Previous submission:
v3: https://lore.kernel.org/linux-iio/20260627005843.7786-3-nikhilgtr@gmail.com/T/#u
v2: https://lore.kernel.org/linux-iio/20260618160141.11409-1-nikhilgtr@gmail.com/T/#t
v1: https://lore.kernel.org/linux-iio/20260510191010.155380-1-nikhilgtr@gmail.com/

Changes in v4:
[DT]
* Updated the example to include the required vdd-supply and
  vddio-supply properties.
* Added fixed regulator nodes to the example so it passes dt_binding_check.

[IIO]
* No Change

Changes in v3:
[DT]

* Made vdd-supply and vddio-supply required properties.
* Moved the MAINTAINERS entry to the correct alphabetical position.

[IIO]

* Added the publicly available MLX90393 datasheet reference.
* Clarified the motivation for introducing a dedicated MLX90393 driver.
* Added the I2C device ID table and switched to designated initializers.
* Added a forward declaration for struct device to reduce unnecessary
  header dependencies.
* Added symbol namespaces.
* Improved include usage.
* Improved status validation and consistency of conditional checks.
* Added comments documenting protocol encoding, initialization delays,
  and temperature conversion constants derived from the datasheet.
* Improved naming, formatting, indentation and general coding style.
* Addressed all review comments from Andy Shevchenko,
  Uwe Kleine-König and Krzysztof Kozlowski.

Changes in v2:
[DT]

* Extended the DT binding to document power supply regulators and
  optional interrupt and trigger GPIOs.

[IIO]

* Removed the RFC tag based on reviewer feedback.
* Added a MAINTAINERS entry as part of the initial submission and
  expanded it in the driver patch.
* Reworked the scale availability implementation to simplify the
  data layout and eliminate the need for constructing a temporary
  table, avoiding potential race conditions.
* Replaced usleep_range() with fsleep() where appropriate and
  documented initialization delays.
* Simplified helper functions and improved error handling by
  returning directly where appropriate.
* Reduced unnecessary local variables and line wrapping to improve
  readability and align with kernel coding style.
* Added comments for lock protection and command definitions to
  improve code clarity.
* Switched to devm_mutex_init() and cleaned up include usage in
  accordance with the "include what you use" principle.
* Improved consistency across the driver, including conditional
  handling, switch statements, formatting and general code style.
* Addressed all review comments from Jonathan Cameron.

Many thanks to Jonathan Cameron, Andy Shevchenko,
Uwe Kleine-König and Krzysztof Kozlowski for their detailed reviews
and valuable feedback, which significantly improved this series.

Further review and comments are greatly appreciated.

Thanks,
Nikhil Gautam

Nikhil Gautam (2):
  dt-bindings: iio: magnetometer: add Melexis MLX90393
  iio: magnetometer: add support for Melexis MLX90393

 .../iio/magnetometer/melexis,mlx90393.yaml    |  63 ++
 MAINTAINERS                                   |   7 +
 drivers/iio/magnetometer/Kconfig              |  10 +
 drivers/iio/magnetometer/Makefile             |   2 +
 drivers/iio/magnetometer/mlx90393.h           |  73 ++
 drivers/iio/magnetometer/mlx90393_core.c      | 701 ++++++++++++++++++
 drivers/iio/magnetometer/mlx90393_i2c.c       |  76 ++
 7 files changed, 932 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
 create mode 100644 drivers/iio/magnetometer/mlx90393.h
 create mode 100644 drivers/iio/magnetometer/mlx90393_core.c
 create mode 100644 drivers/iio/magnetometer/mlx90393_i2c.c

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2.39.5