[PATCH v2 3/3] iio: magnetometer: add driver for QST QMC5883L Sensor

[Siratul Islam <siratul.islam@linux.dev>]

Add driver for the QST QMC5883L 3-Axis Magnetic Sensor
connected via i2c.

Signed-off-by: Siratul Islam <siratul.islam@linux.dev>
---
 MAINTAINERS                         |   1 +
 drivers/iio/magnetometer/Kconfig    |  11 +
 drivers/iio/magnetometer/Makefile   |   2 +
 drivers/iio/magnetometer/qmc5883l.c | 516 ++++++++++++++++++++++++++++
 4 files changed, 530 insertions(+)
 create mode 100644 drivers/iio/magnetometer/qmc5883l.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 1127403c579b..0f9ad3b49a5d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21792,6 +21792,7 @@ M:	Siratul Islam <siratul.islam@linux.dev>
 L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/magnetometer/qstcorp,qmc5883l.yaml
+F:	drivers/iio/magnetometer/qmc5883l.c
 
 QT1010 MEDIA DRIVER
 L:	linux-media@vger.kernel.org
diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index fb313e591e85..615564174086 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -198,6 +198,17 @@ config INFINEON_TLV493D
 	  To compile this driver as a module, choose M here: the module
 	  will be called tlv493d.
 
+config QMC5883L
+	tristate "QST QMC5883L 3-Axis Magnetic Sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say Y here to add support driver for QST QMC5883L 3-Axis
+	  Magnetic Sensor.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called qmc5883l.
+
 config SENSORS_HMC5843
 	tristate
 	select IIO_BUFFER
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index 5bd227f8c120..552682555d86 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -26,6 +26,8 @@ obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
 
 obj-$(CONFIG_INFINEON_TLV493D)		+= tlv493d.o
 
+obj-$(CONFIG_QMC5883L)			+= qmc5883l.o
+
 obj-$(CONFIG_SENSORS_HMC5843)		+= hmc5843_core.o
 obj-$(CONFIG_SENSORS_HMC5843_I2C)	+= hmc5843_i2c.o
 obj-$(CONFIG_SENSORS_HMC5843_SPI)	+= hmc5843_spi.o
diff --git a/drivers/iio/magnetometer/qmc5883l.c b/drivers/iio/magnetometer/qmc5883l.c
new file mode 100644
index 000000000000..e1addcaf0551
--- /dev/null
+++ b/drivers/iio/magnetometer/qmc5883l.c
@@ -0,0 +1,516 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Support for QST QMC5883L 3-Axis Magnetic Sensor on I2C bus.
+ *
+ * Copyright (C) 2026 Siratul Islam <siratul.islam@linux.dev>
+ *
+ * Datasheet available at
+ * <https://www.qstcorp.com/upload/pdf/202512/13-52-04%20QMC5883L%20Datasheet%20Rev.%20B.pdf>
+ *
+ */
+
+#include <linux/array_size.h>
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/cleanup.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/time.h>
+
+#include <linux/iio/iio.h>
+
+#include <asm/byteorder.h>
+
+#define QMC5883L_REG_X_LSB	0x00
+#define QMC5883L_REG_STATUS1	0x06
+#define QMC5883L_REG_CTRL1	0x09
+#define QMC5883L_REG_CTRL2	0x0A
+#define QMC5883L_REG_SET_RESET	0x0B
+#define QMC5883L_REG_ID		0x0D
+
+#define QMC5883L_CHIP_ID	0xFF
+
+#define QMC5883L_MODE_MASK	GENMASK(1, 0)
+#define QMC5883L_ODR_MASK	GENMASK(3, 2)
+#define QMC5883L_RNG_MASK	GENMASK(5, 4)
+#define QMC5883L_OSR_MASK	GENMASK(7, 6)
+
+#define QMC5883L_MODE_STANDBY	0x00
+#define QMC5883L_MODE_CONT	0x01
+
+#define QMC5883L_ODR_10HZ	0x00
+#define QMC5883L_ODR_50HZ	0x01
+#define QMC5883L_ODR_100HZ	0x02
+#define QMC5883L_ODR_200HZ	0x03
+
+#define QMC5883L_RNG_2G		0x00
+#define QMC5883L_RNG_8G		0x01
+
+#define QMC5883L_OSR_512	0x00
+#define QMC5883L_OSR_256	0x01
+#define QMC5883L_OSR_128	0x02
+#define QMC5883L_OSR_64		0x03
+
+#define QMC5883L_STATUS_DRDY	BIT(0)
+#define QMC5883L_STATUS_OVL	BIT(1)
+
+#define QMC5883L_SET_RESET_VAL	BIT(0)
+#define QMC5883L_INT_DISABLE	BIT(0)
+#define QMC5883L_SOFT_RESET	BIT(7)
+
+/* POR completion time max per datasheet */
+#define QMC5883L_PORT_US	350
+
+struct qmc5883l_data {
+	struct regmap *regmap;
+	/*
+	 * Protect data->range/odr/osr.
+	 * Protect poll and read during measurement.
+	 */
+	struct mutex mutex;
+	u8 range;
+	u8 odr;
+	u8 osr;
+};
+
+enum qmc5883l_chan {
+	QMC5883L_AXIS_X,
+	QMC5883L_AXIS_Y,
+	QMC5883L_AXIS_Z
+};
+
+static const int qmc5883l_odr_avail[] = { 10, 50, 100, 200 };
+
+static const int qmc5883l_osr_avail[] = { 512, 256, 128, 64 };
+
+static const int qmc5883l_scales[][2] = {
+	[QMC5883L_RNG_2G] = { 0, 83333 },
+	[QMC5883L_RNG_8G] = { 0, 333333 },
+};
+
+static int qmc5883l_take_measurement(struct iio_dev *indio_dev, int index,
+				     int *val)
+{
+	struct qmc5883l_data *data = iio_priv(indio_dev);
+	unsigned int status;
+	__le16 buf[3];
+	int ret;
+
+	guard(mutex) (&data->mutex);
+
+	/* 50ms headroom over the slowest ODR (10Hz) */
+	ret = regmap_read_poll_timeout(data->regmap,
+				       QMC5883L_REG_STATUS1,
+				       status, (status & QMC5883L_STATUS_DRDY),
+				       2 * USEC_PER_MSEC, 150 * USEC_PER_MSEC);
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(data->regmap, QMC5883L_REG_X_LSB, buf,
+			       sizeof(buf));
+	if (ret)
+		return ret;
+
+	if (status & QMC5883L_STATUS_OVL)
+		return -ERANGE;
+
+	*val = (s16)le16_to_cpu(buf[index]);
+
+	return 0;
+}
+
+static int qmc5883l_read_raw(struct iio_dev *indio_dev,
+			     const struct iio_chan_spec *chan,
+			     int *val, int *val2, long mask)
+{
+	struct qmc5883l_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = qmc5883l_take_measurement(indio_dev, chan->address, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE: {
+		guard(mutex)(&data->mutex);
+
+		*val = qmc5883l_scales[data->range][0];
+		*val2 = qmc5883l_scales[data->range][1];
+
+		return IIO_VAL_INT_PLUS_NANO;
+	}
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		guard(mutex)(&data->mutex);
+
+		switch (data->odr) {
+		case QMC5883L_ODR_200HZ:
+			*val = 200;
+			break;
+		case QMC5883L_ODR_100HZ:
+			*val = 100;
+			break;
+		case QMC5883L_ODR_50HZ:
+			*val = 50;
+			break;
+		case QMC5883L_ODR_10HZ:
+			*val = 10;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		return IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
+		guard(mutex)(&data->mutex);
+
+		switch (data->osr) {
+		case QMC5883L_OSR_64:
+			*val = 64;
+			break;
+		case QMC5883L_OSR_128:
+			*val = 128;
+			break;
+		case QMC5883L_OSR_256:
+			*val = 256;
+			break;
+		case QMC5883L_OSR_512:
+			*val = 512;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		return IIO_VAL_INT;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int qmc5883l_write_raw(struct iio_dev *indio_dev,
+			      const struct iio_chan_spec *chan,
+			      int val, int val2, long mask)
+{
+	struct qmc5883l_data *data = iio_priv(indio_dev);
+	u8 rng, osr, odr;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE: {
+		if (val != 0)
+			return -EINVAL;
+
+		if (val2 == qmc5883l_scales[QMC5883L_RNG_2G][1])
+			rng = QMC5883L_RNG_2G;
+		else if (val2 == qmc5883l_scales[QMC5883L_RNG_8G][1])
+			rng = QMC5883L_RNG_8G;
+		else
+			return -EINVAL;
+
+		guard(mutex)(&data->mutex);
+
+		ret = regmap_update_bits(data->regmap, QMC5883L_REG_CTRL1,
+					 QMC5883L_RNG_MASK,
+					 FIELD_PREP(QMC5883L_RNG_MASK, rng));
+		if (ret)
+			return ret;
+
+		data->range = rng;
+
+		return 0;
+	}
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		switch (val) {
+		case 200:
+			odr = QMC5883L_ODR_200HZ;
+			break;
+		case 100:
+			odr = QMC5883L_ODR_100HZ;
+			break;
+		case 50:
+			odr = QMC5883L_ODR_50HZ;
+			break;
+		case 10:
+			odr = QMC5883L_ODR_10HZ;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		guard(mutex)(&data->mutex);
+
+		ret = regmap_update_bits(data->regmap, QMC5883L_REG_CTRL1,
+					 QMC5883L_ODR_MASK,
+					 FIELD_PREP(QMC5883L_ODR_MASK, odr));
+		if (ret)
+			return ret;
+
+		data->odr = odr;
+
+		return 0;
+	}
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO: {
+		switch (val) {
+		case 64:
+			osr = QMC5883L_OSR_64;
+			break;
+		case 128:
+			osr = QMC5883L_OSR_128;
+			break;
+		case 256:
+			osr = QMC5883L_OSR_256;
+			break;
+		case 512:
+			osr = QMC5883L_OSR_512;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		guard(mutex)(&data->mutex);
+
+		ret = regmap_update_bits(data->regmap, QMC5883L_REG_CTRL1,
+					 QMC5883L_OSR_MASK,
+					 FIELD_PREP(QMC5883L_OSR_MASK, osr));
+		if (ret)
+			return ret;
+
+		data->osr = osr;
+
+		return 0;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int qmc5883l_read_avail(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       const int **vals, int *type, int *length,
+			       long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*vals = qmc5883l_odr_avail;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(qmc5883l_odr_avail);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = qmc5883l_osr_avail;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(qmc5883l_osr_avail);
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_SCALE:
+		*vals = (const int *)qmc5883l_scales;
+		*type = IIO_VAL_INT_PLUS_NANO;
+		*length = ARRAY_SIZE(qmc5883l_scales) * 2;
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int qmc5883l_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;
+	default:
+		return IIO_VAL_INT;
+	}
+}
+
+static const struct iio_info qmc5883l_info = {
+	.read_raw = qmc5883l_read_raw,
+	.write_raw = qmc5883l_write_raw,
+	.read_avail = qmc5883l_read_avail,
+	.write_raw_get_fmt = qmc5883l_write_raw_get_fmt,
+};
+
+static int qmc5883l_init(struct qmc5883l_data *data)
+{
+	struct regmap *regmap = data->regmap;
+	unsigned int reg;
+	int ret;
+
+	ret = regmap_read(regmap, QMC5883L_REG_ID, &reg);
+	if (ret)
+		return ret;
+
+	/* Not failing because rev 1.0 had this register reserved */
+	if (reg != QMC5883L_CHIP_ID)
+		dev_warn(regmap_get_device(regmap),
+			 "Unknown chip id: 0x%02x, continuing\n", reg);
+
+	ret = regmap_write(regmap, QMC5883L_REG_CTRL2, QMC5883L_SOFT_RESET);
+	if (ret)
+		return ret;
+
+	fsleep(QMC5883L_PORT_US);
+
+	/* DRDY pin no used in this version of the driver */
+	ret = regmap_write(regmap, QMC5883L_REG_CTRL2, QMC5883L_INT_DISABLE);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(regmap, QMC5883L_REG_SET_RESET, QMC5883L_SET_RESET_VAL);
+	if (ret)
+		return ret;
+
+	data->odr = QMC5883L_ODR_50HZ;
+	data->range = QMC5883L_RNG_2G;
+	data->osr = QMC5883L_OSR_64;
+
+	return regmap_write(regmap, QMC5883L_REG_CTRL1,
+			    FIELD_PREP(QMC5883L_MODE_MASK, QMC5883L_MODE_CONT) |
+			    FIELD_PREP(QMC5883L_ODR_MASK, data->odr) |
+			    FIELD_PREP(QMC5883L_RNG_MASK, data->range) |
+			    FIELD_PREP(QMC5883L_OSR_MASK, data->osr));
+}
+
+static void qmc5883l_power_down_action(void *priv)
+{
+	struct qmc5883l_data *data = priv;
+
+	regmap_update_bits(data->regmap, QMC5883L_REG_CTRL1,
+			   QMC5883L_MODE_MASK,
+			   FIELD_PREP(QMC5883L_MODE_MASK, QMC5883L_MODE_STANDBY));
+}
+
+static bool qmc5883l_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg <= QMC5883L_REG_STATUS1;
+}
+
+static bool qmc5883l_writable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case QMC5883L_REG_CTRL1:
+	case QMC5883L_REG_CTRL2:
+	case QMC5883L_REG_SET_RESET:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config qmc5883l_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = QMC5883L_REG_ID,
+	.cache_type = REGCACHE_MAPLE,
+	.volatile_reg = qmc5883l_volatile_reg,
+	.writeable_reg = qmc5883l_writable_reg
+};
+
+#define QMC5883L_CHANNEL(_axis)                                \
+	{                                                      \
+		.type = IIO_MAGN,                              \
+		.modified = 1,                                 \
+		.channel2 = IIO_MOD_##_axis,                   \
+		.address = QMC5883L_AXIS_##_axis,              \
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),  \
+		.info_mask_shared_by_type =                    \
+			BIT(IIO_CHAN_INFO_SCALE) |             \
+			BIT(IIO_CHAN_INFO_SAMP_FREQ) |         \
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
+		.info_mask_shared_by_type_available =          \
+			BIT(IIO_CHAN_INFO_SCALE) |             \
+			BIT(IIO_CHAN_INFO_SAMP_FREQ) |         \
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
+	}
+
+static const struct iio_chan_spec qmc5883l_channels[] = {
+	QMC5883L_CHANNEL(X),
+	QMC5883L_CHANNEL(Y),
+	QMC5883L_CHANNEL(Z)
+};
+
+static int qmc5883l_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct qmc5883l_data *data;
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = devm_regmap_init_i2c(client, &qmc5883l_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap),
+				     "regmap initialization failed\n");
+
+	ret = devm_regulator_get_enable(dev, "vdd");
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to enable VDD regulator\n");
+
+	ret = devm_regulator_get_enable(dev, "vddio");
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to enable VDDIO regulator\n");
+
+	fsleep(QMC5883L_PORT_US);
+
+	data = iio_priv(indio_dev);
+	data->regmap = regmap;
+
+	ret = devm_mutex_init(dev, &data->mutex);
+	if (ret)
+		return ret;
+
+	indio_dev->name = "qmc5883l";
+	indio_dev->info = &qmc5883l_info;
+	indio_dev->channels = qmc5883l_channels;
+	indio_dev->num_channels = ARRAY_SIZE(qmc5883l_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = qmc5883l_init(data);
+	if (ret)
+		return dev_err_probe(dev, ret, "qmc5883l init failed\n");
+
+	ret = devm_add_action_or_reset(dev, qmc5883l_power_down_action, data);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id qmc5883l_match[] = {
+	{ .compatible = "qstcorp,qmc5883l" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, qmc5883l_match);
+
+static const struct i2c_device_id qmc5883l_id[] = {
+	{ .name = "qmc5883l" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, qmc5883l_id);
+
+static struct i2c_driver qmc5883l_driver = {
+	.driver = {
+		.name = "qmc5883l",
+		.of_match_table = qmc5883l_match,
+	},
+	.id_table = qmc5883l_id,
+	.probe = qmc5883l_probe
+};
+module_i2c_driver(qmc5883l_driver);
+
+MODULE_DESCRIPTION("QST QMC5883L 3-Axis Magnetic Sensor driver");
+MODULE_AUTHOR("Siratul Islam <siratul.islam@linux.dev>");
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.54.0