(no subject)

[Nikhil Gautam]

Subject: [PATCH v3 0/2] iio: magnetometer: add support for Melexis MLX90393

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:
Link: https://lore.kernel.org/linux-iio/20260510191010.155380-1-nikhilgtr@gmail.com/

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    |  54 ++
 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, 923 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

-- 
2.39.5

[PATCH v3 1/2] dt-bindings: iio: magnetometer: add Melexis MLX90393

[Nikhil Gautam]

Add devicetree bindings for the Melexis MLX90393
3-axis magnetometer and temperature sensor.

The device supports magnetic field and temperature
measurements over I2C and SPI interfaces.

This initial binding documents the I2C interface.

Signed-off-by: Nikhil Gautam <nikhilgtr@gmail.com>
---
 .../iio/magnetometer/melexis,mlx90393.yaml    | 54 +++++++++++++++++++
 MAINTAINERS                                   |  6 +++
 2 files changed, 60 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml b/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
new file mode 100644
index 000000000000..33ab0be66345
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/magnetometer/melexis,mlx90393.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Melexis MLX90393 magnetometer sensor
+
+maintainers:
+  - Nikhil Gautam <nikhilgtr@gmail.com>
+
+description:
+  Melexis MLX90393 3-axis magnetometer and temperature sensor.
+
+properties:
+  compatible:
+    const: melexis,mlx90393
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  trigger-gpios:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - vdd-supply
+  - vddio-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        magnetometer@c {
+            compatible = "melexis,mlx90393";
+            reg = <0x0c>;
+
+            interrupt-parent = <&gpio>;
+            interrupts = <17 IRQ_TYPE_EDGE_RISING>;
+
+            trigger-gpios = <&gpio 18 GPIO_ACTIVE_HIGH>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index a92290fffa16..469ae3f9aa0f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15501,6 +15501,12 @@ F:	Documentation/scsi/megaraid.rst
 F:	drivers/scsi/megaraid.*
 F:	drivers/scsi/megaraid/
 
+MELEXIS MLX90393 MAGNETOMETER DRIVER
+M:	Nikhil Gautam <nikhilgtr@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
+
 MELEXIS MLX90614 DRIVER
 M:	Crt Mori <cmo@melexis.com>
 L:	linux-iio@vger.kernel.org
-- 
2.39.5

Re: [PATCH v3 1/2] dt-bindings: iio: magnetometer: add Melexis MLX90393

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The required properties `vdd-supply` and `vddio-supply` are omitted from the `properties:` block and missing from the `examples:` node, causing schema validation failures.
--

commit c1fe5f8c39a4b8113c50e154a6674ac296637f70
Author: Nikhil Gautam <nikhilgtr@gmail.com>

dt-bindings: iio: magnetometer: add Melexis MLX90393

Add devicetree bindings for the Melexis MLX90393 3-axis magnetometer and
temperature sensor.

> diff --git a/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml b/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
> new file mode 100644
> index 0000000000000..33ab0be663450
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml

[ ... ]

> +properties:
> +  compatible:
> +    const: melexis,mlx90393
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  trigger-gpios:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - vdd-supply
> +  - vddio-supply
> +
> +additionalProperties: false

[Severity: Low]
Will this binding fail schema validation when running dt_binding_check?

The vdd-supply and vddio-supply properties are listed as required, but
they are not defined in the properties block.

Because additionalProperties is set to false, wouldn't the schema reject
these supply properties during validation?

> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        magnetometer@c {
> +            compatible = "melexis,mlx90393";
> +            reg = <0x0c>;
> +
> +            interrupt-parent = <&gpio>;
> +            interrupts = <17 IRQ_TYPE_EDGE_RISING>;
> +
> +            trigger-gpios = <&gpio 18 GPIO_ACTIVE_HIGH>;
> +        };
> +    };

[Severity: Low]
Does this example node need to include the vdd-supply and vddio-supply
properties to pass validation, since they are marked as required above?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260627005843.7786-1-nikhilgtr@gmail.com?part=1

Re: [PATCH v3 1/2] dt-bindings: iio: magnetometer: add Melexis MLX90393

[Rob Herring (Arm)]

On Sat, 27 Jun 2026 06:28:42 +0530, Nikhil Gautam wrote:
> Add devicetree bindings for the Melexis MLX90393
> 3-axis magnetometer and temperature sensor.
> 
> The device supports magnetic field and temperature
> measurements over I2C and SPI interfaces.
> 
> This initial binding documents the I2C interface.
> 
> Signed-off-by: Nikhil Gautam <nikhilgtr@gmail.com>
> ---
>  .../iio/magnetometer/melexis,mlx90393.yaml    | 54 +++++++++++++++++++
>  MAINTAINERS                                   |  6 +++
>  2 files changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.example.dtb: magnetometer@c (melexis,mlx90393): 'vdd-supply' is a required property
	from schema $id: http://devicetree.org/schemas/iio/magnetometer/melexis,mlx90393.yaml
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.example.dtb: magnetometer@c (melexis,mlx90393): 'vddio-supply' is a required property
	from schema $id: http://devicetree.org/schemas/iio/magnetometer/melexis,mlx90393.yaml

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20260627005843.7786-2-nikhilgtr@gmail.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH v3 1/2] dt-bindings: iio: magnetometer: add Melexis MLX90393

[David Lechner]

On 6/26/26 7:58 PM, Nikhil Gautam wrote:
> Add devicetree bindings for the Melexis MLX90393
> 3-axis magnetometer and temperature sensor.
> 
> The device supports magnetic field and temperature
> measurements over I2C and SPI interfaces.
> 
> This initial binding documents the I2C interface.
> 
> Signed-off-by: Nikhil Gautam <nikhilgtr@gmail.com>
> ---
>  .../iio/magnetometer/melexis,mlx90393.yaml    | 54 +++++++++++++++++++
>  MAINTAINERS                                   |  6 +++
>  2 files changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml b/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
> new file mode 100644
> index 000000000000..33ab0be66345
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
> @@ -0,0 +1,54 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/magnetometer/melexis,mlx90393.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Melexis MLX90393 magnetometer sensor
> +
> +maintainers:
> +  - Nikhil Gautam <nikhilgtr@gmail.com>
> +
> +description:
> +  Melexis MLX90393 3-axis magnetometer and temperature sensor.
> +
> +properties:
> +  compatible:
> +    const: melexis,mlx90393
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  trigger-gpios:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - vdd-supply
> +  - vddio-supply

The supplies are required but are missing from the properties and the
example. Running `make dt_binding_check` before sending would have caught
this.

See: https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html

> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        magnetometer@c {
> +            compatible = "melexis,mlx90393";
> +            reg = <0x0c>;
> +
> +            interrupt-parent = <&gpio>;
> +            interrupts = <17 IRQ_TYPE_EDGE_RISING>;
> +
> +            trigger-gpios = <&gpio 18 GPIO_ACTIVE_HIGH>;
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a92290fffa16..469ae3f9aa0f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15501,6 +15501,12 @@ F:	Documentation/scsi/megaraid.rst
>  F:	drivers/scsi/megaraid.*
>  F:	drivers/scsi/megaraid/
>  
> +MELEXIS MLX90393 MAGNETOMETER DRIVER
> +M:	Nikhil Gautam <nikhilgtr@gmail.com>
> +L:	linux-iio@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
> +
>  MELEXIS MLX90614 DRIVER
>  M:	Crt Mori <cmo@melexis.com>
>  L:	linux-iio@vger.kernel.org

[PATCH v3 2/2] iio: magnetometer: add support for Melexis MLX90393

[Nikhil Gautam]

Add Industrial I/O subsystem support for the Melexis
MLX90393 3-axis magnetometer and temperature sensor.

The driver currently supports:

raw magnetic field measurements
raw temperature measurements
configurable gain/scale selection
configurable oversampling ratio
direct mode operation

The MLX90393 supports both I2C and SPI interfaces. This
initial implementation adds support for the I2C interface.

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 without duplicating code.

Signed-off-by: Nikhil Gautam <nikhilgtr@gmail.com>
---
 MAINTAINERS                              |   1 +
 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 +++
 6 files changed, 863 insertions(+)
 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

diff --git a/MAINTAINERS b/MAINTAINERS
index 469ae3f9aa0f..177dda261801 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15506,6 +15506,7 @@ M:	Nikhil Gautam <nikhilgtr@gmail.com>
 L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/magnetometer/melexis,mlx90393.yaml
+F:	drivers/iio/magnetometer/mlx90393*
 
 MELEXIS MLX90614 DRIVER
 M:	Crt Mori <cmo@melexis.com>
diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index 3debf1320ad1..e6b74e7e3317 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -128,6 +128,16 @@ config HID_SENSOR_MAGNETOMETER_3D
 	  Say yes here to build support for the HID SENSOR
 	  Magnetometer 3D.
 
+config MLX90393
+	tristate "MELEXIS MLX90393 3-axis magnetometer sensor"
+	depends on I2C
+	help
+	  Say yes here to build support for the MELEXIS MLX90393 3-axis
+	  magnetometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mlx90393.
+
 config MMC35240
 	tristate "MEMSIC MMC35240 3-axis magnetic sensor"
 	select REGMAP_I2C
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index 9297723a97d8..542c89d38a59 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -14,6 +14,8 @@ obj-$(CONFIG_BMC150_MAGN_SPI) += bmc150_magn_spi.o
 
 obj-$(CONFIG_MAG3110)	+= mag3110.o
 obj-$(CONFIG_HID_SENSOR_MAGNETOMETER_3D) += hid-sensor-magn-3d.o
+obj-$(CONFIG_MLX90393)		+= mlx90393_core.o
+obj-$(CONFIG_MLX90393)		+= mlx90393_i2c.o
 obj-$(CONFIG_MMC35240)	+= mmc35240.o
 
 obj-$(CONFIG_IIO_ST_MAGN_3AXIS) += st_magn.o
diff --git a/drivers/iio/magnetometer/mlx90393.h b/drivers/iio/magnetometer/mlx90393.h
new file mode 100644
index 000000000000..6a646ac05198
--- /dev/null
+++ b/drivers/iio/magnetometer/mlx90393.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * MLX90393 magnetometer & temperature sensor driver
+ *
+ * Copyright (c) 2026 Nikhil Gautam <nikhilgtr@gmail.com>
+ */
+
+#ifndef MLX90393_H
+#define MLX90393_H
+
+#include <linux/bits.h>
+#include <linux/types.h>
+
+#define MLX90393_AXIS_MAX		2
+#define MLX90393_GAIN_MAX		8
+#define MLX90393_RES_MAX		4
+#define MLX90393_OSR2_MAX		4
+#define MLX90393_OSR_MAX		4
+
+#define MLX90393_CMD_MASK        GENMASK(7, 4)
+
+/* Commands (datasheet, Table 11 - Command List) */
+#define MLX90393_CMD_SB        0x10	/* Start Burst Mode */
+#define MLX90393_CMD_SW        0x20	/* Start Wake-up on Change Mode */
+#define MLX90393_CMD_SM        0x30	/* Start Single Measurement Mode */
+#define MLX90393_CMD_RM        0x40	/* Read Measurement */
+#define MLX90393_CMD_RR        0x50	/* Read Register */
+#define MLX90393_CMD_WR        0x60	/* Write Register */
+#define MLX90393_CMD_EX        0x80	/* Exit Mode */
+#define MLX90393_CMD_HR        0xD0	/* Memory Recall */
+#define MLX90393_CMD_HS        0xE0	/* Memory Store */
+#define MLX90393_CMD_RT        0xF0	/* Reset Device */
+
+#define MLX90393_MEASURE_Z    BIT(0)
+#define MLX90393_MEASURE_Y    BIT(1)
+#define MLX90393_MEASURE_X    BIT(2)
+#define MLX90393_MEASURE_TEMP BIT(3)
+
+#define MLX90393_MEASURE_ALL	(MLX90393_MEASURE_TEMP | \
+		MLX90393_MEASURE_X | MLX90393_MEASURE_Y | MLX90393_MEASURE_Z)
+
+#define MLX90393_NUM_CHANNELS	4
+
+#define MLX90393_STATUS_RESP    GENMASK(1, 0)
+#define MLX90393_STATUS_RT	BIT(2)
+#define MLX90393_STATUS_ERROR   BIT(4)
+
+#define MLX90393_REG_CONF1          0x00
+#define MLX90393_REG_CONF2          0x01
+#define MLX90393_REG_CONF3          0x02
+#define MLX90393_REG_CONF4          0x03
+
+#define MLX90393_CONF1_GAIN_SEL     GENMASK(6, 4)
+#define MLX90393_CONF1_HALLCONF     GENMASK(3, 0)
+
+#define MLX90393_CONF3_OSR        GENMASK(1, 0)
+#define MLX90393_CONF3_DIG_FILT   GENMASK(4, 2)
+#define MLX90393_CONF3_RES_X      GENMASK(6, 5)
+#define MLX90393_CONF3_RES_Y      GENMASK(8, 7)
+#define MLX90393_CONF3_RES_Z      GENMASK(10, 9)
+#define MLX90393_CONF3_OSR2       GENMASK(12, 11)
+
+struct device;
+
+struct mlx90393_transfer_ops {
+	int (*xfer)(void *context, const u8 *tx, int tx_len, u8 *rx, int rx_len);
+};
+
+int mlx90393_core_probe(struct device *dev,
+			const struct mlx90393_transfer_ops *ops,
+			void *context);
+
+#endif
diff --git a/drivers/iio/magnetometer/mlx90393_core.c b/drivers/iio/magnetometer/mlx90393_core.c
new file mode 100644
index 000000000000..78fcab8a2b56
--- /dev/null
+++ b/drivers/iio/magnetometer/mlx90393_core.c
@@ -0,0 +1,701 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MLX90393 magnetometer & temperature sensor driver
+ *
+ * Copyright (c) 2026 Nikhil Gautam <nikhilgtr@gmail.com>
+ *
+ * Datasheet: https://media.melexis.com/-/media/files/documents/datasheets/mlx90393-datasheet-melexis.pdf
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/time64.h>
+#include <linux/unaligned.h>
+#include <linux/units.h>
+
+#include <linux/iio/iio.h>
+
+#include "mlx90393.h"
+
+struct mlx90393_data {
+	/* Protects sensor configuration and measurement operations */
+	struct mutex lock;
+	struct device *dev;
+	void *bus_context;
+	const struct mlx90393_transfer_ops *ops;
+	u8 gain_sel;
+	u8 hallconf;
+
+	u8 res_xy;
+	u8 res_z;
+
+	u8 dig_filt;
+	u8 osr;
+	u8 osr2;
+};
+
+enum mlx90393_channels {
+	MLX90393_CHAN_X,
+	MLX90393_CHAN_Y,
+	MLX90393_CHAN_Z,
+	MLX90393_CHAN_TEMP,
+};
+
+enum mlx90393_axis_type {
+	MLX90393_AXIS_TYPE_XY,
+	MLX90393_AXIS_TYPE_Z,
+};
+
+/* Datasheet: Table no.17 */
+static const int mlx90393_scale_table[MLX90393_AXIS_MAX][MLX90393_GAIN_MAX]
+				      [MLX90393_RES_MAX] = {
+	/* XY axis */
+	{
+		{ 751, 1502, 3004, 6009},
+		{ 601, 1202, 2403, 4840},
+		{ 451, 901, 1803, 3605},
+		{ 376, 751, 1502, 3004},
+		{ 300, 601, 1202, 2403},
+		{ 250, 501, 1001, 2003},
+		{ 200, 401, 801, 1602},
+		{ 150, 300, 601, 1202},
+	},
+	/* Z axis */
+	{
+		{ 1210, 2420, 4840, 9680},
+		{ 968, 1936, 3872, 7744},
+		{ 726, 1452, 2904, 5808},
+		{ 605, 1210, 2420, 4840},
+		{ 484, 968, 1936, 3872},
+		{ 403, 807, 1613, 3227},
+		{ 323, 645, 1291, 2581},
+		{ 242, 484, 968, 1936},
+	}
+};
+
+static const int mlx90393_osr2_avail[MLX90393_OSR2_MAX] = {
+	0, 1, 2, 3,
+};
+
+static const int mlx90393_osr_avail[MLX90393_OSR_MAX] = {
+	1, 2, 4, 8,
+};
+
+#define MLX90393_CHAN(idx, axis, addr) { \
+	.type = IIO_MAGN, \
+	.modified = 1, \
+	.channel = idx, \
+	.address = addr, \
+	.channel2 = IIO_MOD_##axis, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
+		BIT(IIO_CHAN_INFO_SCALE), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),\
+	.info_mask_separate_available = \
+		BIT(IIO_CHAN_INFO_SCALE),  \
+	.info_mask_shared_by_type_available = \
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
+}
+
+static const struct iio_chan_spec mlx90393_channels[] = {
+	MLX90393_CHAN(0, X, MLX90393_CHAN_X),
+	MLX90393_CHAN(1, Y, MLX90393_CHAN_Y),
+	MLX90393_CHAN(2, Z, MLX90393_CHAN_Z),
+	{
+		.type = IIO_TEMP,
+		.address = MLX90393_CHAN_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_OFFSET) |
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_separate_available =
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+/*
+ * Calculate total conversion time in microseconds.
+ *
+ * Formula derived from datasheet timing equations.
+ * Datasheet: Table 8, Page no. 12
+ *
+ * Abbreviations:
+ * TCONVM	-> Single Magnetic axis conversion time
+ * TCONVT	-> Temperature conversion time
+ * TSTBY	-> Time from IDLE to STANDBY
+ * TACTIVE	-> Time from STBY to ACTIVE
+ * TCONV_END	-> Time to end analog active mode
+ */
+static int mlx90393_get_tconv_us(struct mlx90393_data *data)
+{
+	const int osr = data->osr;
+	const int osr2 = data->osr2;
+	const int df = data->dig_filt;
+
+	int tconvm;
+	int tconvt;
+
+	int m = 3; /* X,Y,Z */
+
+	/*
+	 * TCONVM = 67 + 64 * 2^OSR * (2 + 2^DIG_FILT)
+	 */
+	tconvm = 67 + (64 * BIT(osr) * (2 + BIT(df)));
+
+	/*
+	 * TCONVT = 67 + 192 * 2^OSR2
+	 */
+	tconvt = 67 + (192 * BIT(osr2));
+	/*
+	 * Total conversion time:
+	 * TSTBY + TACTIVE + m * TCONVM + TCONVT + TCONV_END
+	 */
+	return 220 + 360 + (m * tconvm) + tconvt + 120;
+}
+
+static int mlx90393_xfer(struct mlx90393_data *data,
+			 const u8 *tx, int tx_len,
+			 u8 *rx, int rx_len)
+{
+	return data->ops->xfer(data->bus_context, tx, tx_len, rx, rx_len);
+}
+
+static int mlx90393_check_status(u8 cmd, u8 status)
+{
+	/* Datasheet: Table 12: Status byte definition */
+
+	/* Always validate error bit */
+	if (status & MLX90393_STATUS_ERROR)
+		return -EIO;
+
+	switch (cmd & MLX90393_CMD_MASK) {
+	case MLX90393_CMD_RM:
+		/*
+		 * D1:D0 indicates response availability
+		 * 00 means invalid/no measurement
+		 */
+		if ((status & MLX90393_STATUS_RESP) == 0)
+			return -EIO;
+		return 0;
+	case MLX90393_CMD_RT:
+		/* Reset acknowledge */
+		if ((status & MLX90393_STATUS_RT) == 0)
+			return -EIO;
+		return 0;
+	default:
+		return 0;
+	}
+}
+
+static int mlx90393_write_cmd(struct mlx90393_data *data, u8 cmd)
+{
+	u8 status;
+	int ret;
+
+	ret = mlx90393_xfer(data, &cmd, 1, &status, 1);
+	if (ret)
+		return ret;
+
+	return mlx90393_check_status(cmd, status);
+}
+
+static int mlx90393_read_cmd(struct mlx90393_data *data, u8 cmd, u8 *rx,
+			     int rx_len)
+{
+	int ret;
+
+	ret = mlx90393_xfer(data, &cmd, 1, rx, rx_len);
+	if (ret)
+		return ret;
+
+	return mlx90393_check_status(cmd, rx[0]);
+}
+
+static int mlx90393_read_reg(struct mlx90393_data *data, u8 reg, u16 *val)
+{
+	u8 tx[2];
+	u8 rx[3];
+	int ret;
+
+	tx[0] = MLX90393_CMD_RR;
+	/* Register address is encoded in bits [7:2] */
+	tx[1] = reg << 2;
+
+	ret = mlx90393_xfer(data, tx, sizeof(tx), rx, sizeof(rx));
+	if (ret)
+		return ret;
+
+	ret = mlx90393_check_status(tx[0], rx[0]);
+	if (ret)
+		return ret;
+
+	*val = get_unaligned_be16(&rx[1]);
+
+	return 0;
+}
+
+static int mlx90393_write_reg(struct mlx90393_data *data, u8 reg, u16 val)
+{
+	u8 tx[4];
+	u8 status;
+	int ret;
+
+	tx[0] = MLX90393_CMD_WR;
+	put_unaligned_be16(val, &tx[1]);
+	/* Register address is encoded in bits [7:2] */
+	tx[3] = reg << 2;
+
+	ret = mlx90393_xfer(data, tx, sizeof(tx), &status, 1);
+	if (ret)
+		return ret;
+
+	return mlx90393_check_status(tx[0], status);
+}
+
+static int mlx90393_update_bits(struct mlx90393_data *data, u8 reg,
+				u16 mask, u16 val)
+{
+	u16 reg_val;
+	int ret;
+
+	ret = mlx90393_read_reg(data, reg, &reg_val);
+	if (ret)
+		return ret;
+
+	reg_val &= ~mask;
+	reg_val |= (val << __ffs(mask)) & mask;
+
+	return mlx90393_write_reg(data, reg, reg_val);
+}
+
+static int mlx90393_read_measurement(struct mlx90393_data *data,
+				     enum mlx90393_channels chan, int *val)
+{
+	u8 rx[9];
+	int ret;
+
+	/* Start measurement */
+	ret = mlx90393_write_cmd(data, MLX90393_CMD_SM | MLX90393_MEASURE_ALL);
+	if (ret)
+		return ret;
+
+	/* Wait conversion */
+	fsleep(mlx90393_get_tconv_us(data));
+
+	/* Read measurement */
+	ret = mlx90393_read_cmd(data, MLX90393_CMD_RM | MLX90393_MEASURE_ALL,
+				rx, sizeof(rx));
+	if (ret)
+		return ret;
+	/*
+	 * Measurement response layout:
+	 * [status][temp][x][y][z]
+	 */
+
+	switch (chan) {
+	case MLX90393_CHAN_TEMP:
+		*val = get_unaligned_be16(&rx[1]);
+		return 0;
+
+	case MLX90393_CHAN_X:
+		*val = sign_extend32(get_unaligned_be16(&rx[3]), 15);
+		return 0;
+
+	case MLX90393_CHAN_Y:
+		*val = sign_extend32(get_unaligned_be16(&rx[5]), 15);
+		return 0;
+
+	case MLX90393_CHAN_Z:
+		*val = sign_extend32(get_unaligned_be16(&rx[7]), 15);
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mlx90393_get_scale(struct mlx90393_data *data,
+			      const struct iio_chan_spec *chan,
+			      int *val, int *val2)
+{
+	enum mlx90393_axis_type axis;
+	u8 res;
+
+	if (chan->channel2 == IIO_MOD_Z) {
+		axis = MLX90393_AXIS_TYPE_Z;
+		res = data->res_z;
+	} else {
+		axis = MLX90393_AXIS_TYPE_XY;
+		res = data->res_xy;
+	}
+
+	*val = 0;
+	*val2 = mlx90393_scale_table[axis][data->gain_sel][res];
+
+	return IIO_VAL_INT_PLUS_NANO;
+}
+
+static int mlx90393_find_scale(struct mlx90393_data *data, bool z_axis,
+			       int val, int val2,
+			       int *gain)
+{
+	u8 res;
+	enum mlx90393_axis_type axis;
+
+	if (z_axis) {
+		axis = MLX90393_AXIS_TYPE_Z;
+		res = data->res_z;
+	} else {
+		axis = MLX90393_AXIS_TYPE_XY;
+		res = data->res_xy;
+	}
+
+	if (val != 0)
+		return -EINVAL;
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(mlx90393_scale_table[0]); i++) {
+		if (mlx90393_scale_table[axis][i][res] == val2) {
+			*gain = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int mlx90393_set_scale(struct mlx90393_data *data,
+			      const struct iio_chan_spec *chan,
+			      int val, int val2)
+{
+	bool z_axis;
+	int gain;
+	int ret;
+
+	z_axis = chan->channel2 == IIO_MOD_Z;
+
+	ret = mlx90393_find_scale(data, z_axis, val, val2, &gain);
+	if (ret)
+		return ret;
+
+	ret = mlx90393_update_bits(data, MLX90393_REG_CONF1, MLX90393_CONF1_GAIN_SEL,
+				   gain);
+	if (ret)
+		return ret;
+
+	data->gain_sel = gain;
+	return 0;
+}
+
+static int mlx90393_get_osr(struct mlx90393_data *data, int *val)
+{
+	*val = mlx90393_osr_avail[data->osr];
+	return IIO_VAL_INT;
+}
+
+static int mlx90393_find_osr(int val, int *osr)
+{
+	for (unsigned int i = 0; i < MLX90393_OSR_MAX;  i++) {
+		if (mlx90393_osr_avail[i] == val) {
+			*osr = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int mlx90393_get_temp_osr2(struct mlx90393_data *data, int *val)
+{
+	*val = mlx90393_osr2_avail[data->osr2];
+	return IIO_VAL_INT;
+}
+
+static int mlx90393_set_osr(struct mlx90393_data *data, int val)
+{
+	int osr;
+	int ret;
+
+	ret = mlx90393_find_osr(val, &osr);
+	if (ret)
+		return ret;
+
+	if (osr == data->osr)
+		return 0;
+
+	ret = mlx90393_update_bits(data, MLX90393_REG_CONF3, MLX90393_CONF3_OSR,
+				   osr);
+	if (ret)
+		return ret;
+
+	data->osr = osr;
+	return 0;
+}
+
+static int mlx90393_set_temp_osr2(struct mlx90393_data *data, int val)
+{
+	int ret;
+
+	if (val < 0 || val >= MLX90393_OSR2_MAX)
+		return -EINVAL;
+
+	if (val == data->osr2)
+		return 0;
+
+	ret = mlx90393_update_bits(data, MLX90393_REG_CONF3, MLX90393_CONF3_OSR2,
+				   val);
+	if (ret)
+		return ret;
+
+	data->osr2 = val;
+
+	return 0;
+}
+
+static int mlx90393_write_raw_get_fmt(struct iio_dev *indio_dev,
+				      struct iio_chan_spec const *chan,
+				      long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_NANO;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mlx90393_write_raw(struct iio_dev *indio_dev,
+			      const struct iio_chan_spec *chan,
+			      int val, int val2,
+			      long mask)
+{
+	struct mlx90393_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE: {
+		guard(mutex)(&data->lock);
+		return mlx90393_set_scale(data, chan, val, val2);
+	}
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
+		guard(mutex)(&data->lock);
+		switch (chan->type) {
+		case IIO_TEMP:
+			return mlx90393_set_temp_osr2(data, val);
+
+		case IIO_MAGN:
+			return mlx90393_set_osr(data, val);
+
+		default:
+			return -EINVAL;
+		}
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mlx90393_read_raw(struct iio_dev *indio_dev,
+			     const struct iio_chan_spec *chan,
+			     int *val, int *val2, long mask)
+{
+	struct mlx90393_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		guard(mutex)(&data->lock);
+		ret = mlx90393_read_measurement(data, chan->address, val);
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_MAGN:
+			return mlx90393_get_scale(data, chan, val, val2);
+
+		case IIO_TEMP:
+			/*
+			 * Datasheet Table 7: Thermal Specification
+			 */
+			*val = 0;
+			*val2 = 22124;
+			return IIO_VAL_INT_PLUS_MICRO;
+
+		default:
+			return -EINVAL;
+		}
+
+	case IIO_CHAN_INFO_OFFSET:
+		if (chan->type != IIO_TEMP)
+			return -EINVAL;
+		/*
+		 * Datasheet Table 7: Thermal Specification
+		 */
+
+		*val = -45114;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		switch (chan->type) {
+		case IIO_TEMP:
+			return mlx90393_get_temp_osr2(data, val);
+		case IIO_MAGN:
+			return mlx90393_get_osr(data, val);
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mlx90393_read_avail(struct iio_dev *indio_dev,
+			       const struct iio_chan_spec *chan,
+			       const int **vals,
+			       int *type,
+			       int *length,
+			       long mask)
+{
+	struct mlx90393_data *data = iio_priv(indio_dev);
+	static int scale_avail[MLX90393_GAIN_MAX][MLX90393_AXIS_MAX];
+	enum mlx90393_axis_type axis;
+	u8 res;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE: {
+		guard(mutex)(&data->lock);
+		axis = chan->channel2 == IIO_MOD_Z;
+		res = axis ? data->res_z : data->res_xy;
+
+		for (unsigned int i = 0; i < MLX90393_GAIN_MAX; i++) {
+			scale_avail[i][0] = 0;
+			scale_avail[i][1] =
+				mlx90393_scale_table[axis][i][res];
+		}
+
+		*vals = &scale_avail[0][0];
+		*type = IIO_VAL_INT_PLUS_NANO;
+		*length = MLX90393_GAIN_MAX * MLX90393_AXIS_MAX;
+		return IIO_AVAIL_LIST;
+	}
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		if (chan->type == IIO_TEMP) {
+			*vals = mlx90393_osr2_avail;
+			*type = IIO_VAL_INT;
+			*length = MLX90393_OSR2_MAX;
+		} else {
+			*vals = mlx90393_osr_avail;
+			*type = IIO_VAL_INT;
+			*length = MLX90393_OSR_MAX;
+		}
+		return IIO_AVAIL_LIST;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info mlx90393_info = {
+	.read_raw = mlx90393_read_raw,
+	.write_raw = mlx90393_write_raw,
+	.read_avail = mlx90393_read_avail,
+	.write_raw_get_fmt = mlx90393_write_raw_get_fmt,
+};
+
+static int mlx90393_init(struct mlx90393_data *data)
+{
+	int ret;
+	u16 reg;
+
+	/* Exit mode */
+	ret = mlx90393_write_cmd(data, MLX90393_CMD_EX);
+	if (ret)
+		return ret;
+
+	/*
+	 * Datasheet section 15.4.1.2 (RT command), Figure 16:
+	 * Wait 1 ms after EX command before issuing RT.
+	 */
+	fsleep(1 * USEC_PER_MSEC);
+
+	/* Reset device */
+	ret = mlx90393_write_cmd(data, MLX90393_CMD_RT);
+	if (ret)
+		return ret;
+
+	/*
+	 * Datasheet section 15.4.1.2 (RT command), Figure 16:
+	 * Wait 1.5 ms for the start-up sequence to complete.
+	 */
+	fsleep(1.5 * USEC_PER_MSEC);
+
+	ret = mlx90393_read_reg(data, MLX90393_REG_CONF1, &reg);
+	if (ret)
+		return ret;
+
+	data->gain_sel = FIELD_GET(MLX90393_CONF1_GAIN_SEL, reg);
+	data->hallconf = FIELD_GET(MLX90393_CONF1_HALLCONF, reg);
+
+	ret = mlx90393_read_reg(data, MLX90393_REG_CONF3, &reg);
+	if (ret)
+		return ret;
+
+	data->res_xy = FIELD_GET(MLX90393_CONF3_RES_X, reg);
+	data->res_z = FIELD_GET(MLX90393_CONF3_RES_Z, reg);
+	data->dig_filt = FIELD_GET(MLX90393_CONF3_DIG_FILT, reg);
+	data->osr = FIELD_GET(MLX90393_CONF3_OSR, reg);
+	data->osr2 = FIELD_GET(MLX90393_CONF3_OSR2, reg);
+
+	return 0;
+}
+
+int mlx90393_core_probe(struct device *dev,
+			const struct mlx90393_transfer_ops *ops,
+			void *context)
+{
+	struct iio_dev *indio_dev;
+	struct mlx90393_data *data;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	ret = devm_mutex_init(dev, &data->lock);
+	if (ret)
+		return ret;
+
+	data->dev = dev;
+	data->ops = ops;
+	data->bus_context = context;
+
+	indio_dev->name = "mlx90393";
+	indio_dev->info = &mlx90393_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mlx90393_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mlx90393_channels);
+
+	ret = mlx90393_init(data);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to initialize device\n");
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+EXPORT_SYMBOL_NS_GPL(mlx90393_core_probe, "IIO_MLX90393");
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nikhil Gautam <nikhilgtr@gmail.com>");
+MODULE_DESCRIPTION("MLX90393 magnetometer sensor driver");
diff --git a/drivers/iio/magnetometer/mlx90393_i2c.c b/drivers/iio/magnetometer/mlx90393_i2c.c
new file mode 100644
index 000000000000..a9f0a40d15e8
--- /dev/null
+++ b/drivers/iio/magnetometer/mlx90393_i2c.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/array_size.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+
+#include "mlx90393.h"
+
+/*
+ * MLX90393 commands use repeated-start transfers where
+ * every command is followed by a status/data response.
+ */
+static int mlx90393_i2c_xfer(void *context,
+			     const u8 *tx, int tx_len,
+			     u8 *rx, int rx_len)
+{
+	struct i2c_client *client = context;
+	int ret;
+	struct i2c_msg msgs[2] = {
+		[0] = {
+			.addr = client->addr,
+			.len = tx_len,
+			.buf = (u8 *)tx,
+		},
+		[1] = {
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = rx_len,
+			.buf = rx,
+		},
+	};
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret != ARRAY_SIZE(msgs))
+		return ret < 0 ? ret : -EIO;
+
+	return 0;
+}
+
+static const struct mlx90393_transfer_ops mlx90393_i2c_ops = {
+	.xfer = mlx90393_i2c_xfer,
+};
+
+static int mlx90393_i2c_probe(struct i2c_client *client)
+{
+	return mlx90393_core_probe(&client->dev, &mlx90393_i2c_ops, client);
+}
+
+static const struct i2c_device_id mlx90393_id[] = {
+	{ .name = "mlx90393" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mlx90393_id);
+
+static const struct of_device_id mlx90393_of_match[] = {
+	{ .compatible = "melexis,mlx90393" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mlx90393_of_match);
+
+static struct i2c_driver mlx90393_i2c_driver = {
+	.driver = {
+		.name = "mlx90393",
+		.of_match_table = mlx90393_of_match,
+	},
+	.probe = mlx90393_i2c_probe,
+	.id_table = mlx90393_id,
+};
+
+module_i2c_driver(mlx90393_i2c_driver);
+
+MODULE_IMPORT_NS("IIO_MLX90393");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Nikhil Gautam <nikhilgtr@gmail.com>");
+MODULE_DESCRIPTION("MLX90393 magnetometer sensor driver");
-- 
2.39.5

Re: [PATCH v3 2/2] iio: magnetometer: add support for Melexis MLX90393

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 9 potential issue(s) to consider:
- [High] TOCTOU data race in `mlx90393_read_avail` due to static array.
- [High] Stack-allocated buffers passed to I2C transport violate DMA rules.
- [High] `mlx90393_check_status` rejects valid responses for 4-axis reads.
- [Medium] Writing to `in_temp_scale` silently corrupts magnetometer gain configuration.
- [Medium] Incorrect physical units exposed for IIO scales (ABI violation).
- [Medium] Temperature oversampling ratio exposes internal register indices (ABI violation).
- [Low] Use of floating-point literal in `fsleep` duration.
- [Low] Misuse of `MLX90393_AXIS_MAX` for scale array length.
- [Low] Data race on configuration variables in `mlx90393_read_raw`.
--

commit 615b644e2712a4949015c117e64d449d197438d8
Author: Nikhil Gautam <nikhilgtr@gmail.com>

iio: magnetometer: add support for Melexis MLX90393

Add Industrial I/O subsystem support for the Melexis MLX90393 3-axis
magnetometer and temperature sensor.

> diff --git a/drivers/iio/magnetometer/mlx90393_core.c b/drivers/iio/magnetometer/mlx90393_core.c
> index 0000000000000..78fcab8a2b566 100644
> --- /dev/null
> +++ b/drivers/iio/magnetometer/mlx90393_core.c
[ ... ]
> +static const int mlx90393_osr2_avail[MLX90393_OSR2_MAX] = {
> +	0, 1, 2, 3,
> +};

[Severity: Medium]
Should this array expose the physical oversampling ratios (e.g., 1, 2, 4, 8)
rather than the internal register values, to comply with IIO ABI standards?

[ ... ]
> +static int mlx90393_check_status(u8 cmd, u8 status)
> +{
> +	/* Datasheet: Table 12: Status byte definition */
> +
> +	/* Always validate error bit */
> +	if (status & MLX90393_STATUS_ERROR)
> +		return -EIO;
> +
> +	switch (cmd & MLX90393_CMD_MASK) {
> +	case MLX90393_CMD_RM:
> +		/*
> +		 * D1:D0 indicates response availability
> +		 * 00 means invalid/no measurement
> +		 */
> +		if ((status & MLX90393_STATUS_RESP) == 0)
> +			return -EIO;

[Severity: High]
Does this validation break 4-axis reads?

If MLX90393_MEASURE_ALL requests 4 words, could the 2-bit counter overflow
to 00, causing the driver to incorrectly reject valid responses?

[ ... ]
> +static int mlx90393_write_reg(struct mlx90393_data *data, u8 reg, u16 val)
> +{
> +	u8 tx[4];
> +	u8 status;
> +	int ret;
> +
> +	tx[0] = MLX90393_CMD_WR;
> +	put_unaligned_be16(val, &tx[1]);
> +	/* Register address is encoded in bits [7:2] */
> +	tx[3] = reg << 2;
> +
> +	ret = mlx90393_xfer(data, tx, sizeof(tx), &status, 1);

[Severity: High]
Can passing stack-allocated buffers to the I2C transport cause memory
corruption or a kernel panic?

If the underlying I2C controller uses DMA, mapping stack memory (which might
be CONFIG_VMAP_STACK) is generally not allowed. This also applies to the rx
buffer in mlx90393_read_measurement().

[ ... ]
> +static int mlx90393_get_scale(struct mlx90393_data *data,
> +			      const struct iio_chan_spec *chan,
> +			      int *val, int *val2)
> +{
> +	enum mlx90393_axis_type axis;
> +	u8 res;
> +
> +	if (chan->channel2 == IIO_MOD_Z) {
> +		axis = MLX90393_AXIS_TYPE_Z;
> +		res = data->res_z;
> +	} else {
> +		axis = MLX90393_AXIS_TYPE_XY;
> +		res = data->res_xy;
> +	}
> +
> +	*val = 0;
> +	*val2 = mlx90393_scale_table[axis][data->gain_sel][res];
> +
> +	return IIO_VAL_INT_PLUS_NANO;

[Severity: Medium]
Do these return values violate the IIO ABI?

Is the magnetometer scale exposing Tesla (nano scale) instead of Gauss?

[ ... ]
> +static int mlx90393_write_raw(struct iio_dev *indio_dev,
> +			      const struct iio_chan_spec *chan,
> +			      int val, int val2,
> +			      long mask)
> +{
> +	struct mlx90393_data *data = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE: {
> +		guard(mutex)(&data->lock);
> +		return mlx90393_set_scale(data, chan, val, val2);
> +	}

[Severity: Medium]
Does this lack of chan->type checking mean writes to the temperature scale
sysfs attribute will fall through to mlx90393_set_scale()?

Could this unintentionally alter the magnetometer gain configuration?

[ ... ]
> +static int mlx90393_read_raw(struct iio_dev *indio_dev,
> +			     const struct iio_chan_spec *chan,
> +			     int *val, int *val2, long mask)
> +{
> +	struct mlx90393_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW: {
> +		guard(mutex)(&data->lock);
> +		ret = mlx90393_read_measurement(data, chan->address, val);
> +		if (ret)
> +			return ret;
> +
> +		return IIO_VAL_INT;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_MAGN:
> +			return mlx90393_get_scale(data, chan, val, val2);

[Severity: Low]
Does reading driver configuration fields like data->gain_sel in
mlx90393_get_scale() without holding data->lock introduce a data race with
concurrent sysfs writes in mlx90393_write_raw()?

> +
> +		case IIO_TEMP:
> +			/*
> +			 * Datasheet Table 7: Thermal Specification
> +			 */
> +			*val = 0;
> +			*val2 = 22124;
> +			return IIO_VAL_INT_PLUS_MICRO;

[Severity: Medium]
Does this violate the IIO ABI by exposing Celsius instead of milli-Celsius?

[ ... ]
> +static int mlx90393_read_avail(struct iio_dev *indio_dev,
> +			       const struct iio_chan_spec *chan,
> +			       const int **vals,
> +			       int *type,
> +			       int *length,
> +			       long mask)
> +{
> +	struct mlx90393_data *data = iio_priv(indio_dev);
> +	static int scale_avail[MLX90393_GAIN_MAX][MLX90393_AXIS_MAX];

[Severity: High]
Is it safe to populate and return a pointer to a static array here?

Since the IIO core reads this array outside the driver's lock, couldn't a
concurrent sysfs read from another thread or device overwrite the array
contents while it's being read?

[ ... ]
> +		*vals = &scale_avail[0][0];
> +		*type = IIO_VAL_INT_PLUS_NANO;
> +		*length = MLX90393_GAIN_MAX * MLX90393_AXIS_MAX;

[Severity: Low]
Is MLX90393_AXIS_MAX being misused here to calculate the length?

While it evaluates to 2, shouldn't length represent the number of values
(entries * 2 elements per IIO value pair) rather than axis count?

[ ... ]
> +static int mlx90393_init(struct mlx90393_data *data)
> +{
> +	int ret;
> +	u16 reg;
> +
> +	/* Exit mode */
> +	ret = mlx90393_write_cmd(data, MLX90393_CMD_EX);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * Datasheet section 15.4.1.2 (RT command), Figure 16:
> +	 * Wait 1 ms after EX command before issuing RT.
> +	 */
> +	fsleep(1 * USEC_PER_MSEC);
> +
> +	/* Reset device */
> +	ret = mlx90393_write_cmd(data, MLX90393_CMD_RT);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * Datasheet section 15.4.1.2 (RT command), Figure 16:
> +	 * Wait 1.5 ms for the start-up sequence to complete.
> +	 */
> +	fsleep(1.5 * USEC_PER_MSEC);

[Severity: Low]
Could using a floating-point literal (1.5) cause build or linkage errors
on architectures where hardware floating-point arithmetic is not supported
in the kernel?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260627005843.7786-1-nikhilgtr@gmail.com?part=2

Re: [PATCH v3 0/2] iio: magnetometer: add support for Melexis MLX90393

[David Lechner]

On 6/26/26 7:58 PM, Nikhil Gautam wrote:
> Subject: [PATCH v3 0/2] iio: magnetometer: add support for Melexis MLX90393
> 
It is best not to manually edit the emails before sending. Somehow the
subject ended up in the email body.