iio: magnetometer: add Allegro MicroSystems ALS31300 3-D Linear Hall Effect driver

The Allegro MicroSystems ALS31300 is a 3-D Linear Hall Effect Sensor
mainly used for 3D head-on motion sensing applications.

The device is configured over I2C, and as part of the Sensor data the
temperature core is also provided.

While the device provides an IRQ gpio, it depends on a configuration
programmed into the internal EEPROM, thus only the default mode is
supported and buffered input via trigger is also supported to allow
streaming values with the same sensing timestamp.

The device can be configured with different sensitivities in factory,
but the sensitivity value used to calculate value into the Gauss
unit is not available from registers, thus the sensitivity is provided
by the compatible/device-id string which is based on the part number
as described in the datasheet page 2.

Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20241030-topic-input-upstream-als31300-v4-3-494297c9e50a@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

3 files changed, 508 insertions, 0 deletions

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index f69ac75500f9..7177cd1d67cb 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -54,6 +54,19 @@ config AK09911
 	help
 	  Deprecated: AK09911 is now supported by AK8975 driver.
 
+config ALS31300
+	tristate "Allegro MicroSystems ALS31300 3-D Linear Hall Effect Sensor"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for the Allegro MicroSystems
+	  ALS31300 Hall Effect Sensor through its I2C interface.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called als31300.
+
 config BMC150_MAGN
 	tristate
 	select IIO_BUFFER
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index ec5c46fbf999..3e4c2ecd9adf 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -7,6 +7,7 @@
 obj-$(CONFIG_AF8133J)	+= af8133j.o
 obj-$(CONFIG_AK8974)	+= ak8974.o
 obj-$(CONFIG_AK8975)	+= ak8975.o
+obj-$(CONFIG_ALS31300)	+= als31300.o
 obj-$(CONFIG_BMC150_MAGN) += bmc150_magn.o
 obj-$(CONFIG_BMC150_MAGN_I2C) += bmc150_magn_i2c.o
 obj-$(CONFIG_BMC150_MAGN_SPI) += bmc150_magn_spi.o
diff --git a/drivers/iio/magnetometer/als31300.c b/drivers/iio/magnetometer/als31300.c
new file mode 100644
index 000000000000..87b60c4e81fa
--- /dev/null
+++ b/drivers/iio/magnetometer/als31300.c
@@ -0,0 +1,494 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for the Allegro MicroSystems ALS31300 3-D Linear Hall Effect Sensor
+ *
+ * Copyright (c) 2024 Linaro Limited
+ */
+
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+/*
+ * The Allegro MicroSystems ALS31300 has an EEPROM space to configure how
+ * the device works and how the interrupt line behaves.
+ * Only the default setup with external trigger is supported.
+ *
+ * While the bindings supports declaring an interrupt line, those
+ * events are not supported.
+ *
+ * It should be possible to adapt the driver to the current
+ * device EEPROM setup at runtime.
+ */
+
+#define ALS31300_EEPROM_CONFIG		0x02
+#define ALS31300_EEPROM_INTERRUPT	0x03
+#define ALS31300_EEPROM_CUSTOMER_1	0x0d
+#define ALS31300_EEPROM_CUSTOMER_2	0x0e
+#define ALS31300_EEPROM_CUSTOMER_3	0x0f
+#define ALS31300_VOL_MODE		0x27
+#define ALS31300_VOL_MODE_LPDCM			GENMASK(6, 4)
+#define   ALS31300_LPDCM_INACTIVE_0_5_MS	0
+#define   ALS31300_LPDCM_INACTIVE_1_0_MS	1
+#define   ALS31300_LPDCM_INACTIVE_5_0_MS	2
+#define   ALS31300_LPDCM_INACTIVE_10_0_MS	3
+#define   ALS31300_LPDCM_INACTIVE_50_0_MS	4
+#define   ALS31300_LPDCM_INACTIVE_100_0_MS	5
+#define   ALS31300_LPDCM_INACTIVE_500_0_MS	6
+#define   ALS31300_LPDCM_INACTIVE_1000_0_MS	7
+#define ALS31300_VOL_MODE_SLEEP			GENMASK(1, 0)
+#define   ALS31300_VOL_MODE_ACTIVE_MODE		0
+#define   ALS31300_VOL_MODE_SLEEP_MODE		1
+#define   ALS31300_VOL_MODE_LPDCM_MODE		2
+#define ALS31300_VOL_MSB		0x28
+#define ALS31300_VOL_MSB_TEMPERATURE		GENMASK(5, 0)
+#define ALS31300_VOL_MSB_INTERRUPT		BIT(6)
+#define ALS31300_VOL_MSB_NEW_DATA		BIT(7)
+#define ALS31300_VOL_MSB_Z_AXIS			GENMASK(15, 8)
+#define ALS31300_VOL_MSB_Y_AXIS			GENMASK(23, 16)
+#define ALS31300_VOL_MSB_X_AXIS			GENMASK(31, 24)
+#define ALS31300_VOL_LSB		0x29
+#define ALS31300_VOL_LSB_TEMPERATURE		GENMASK(5, 0)
+#define ALS31300_VOL_LSB_HALL_STATUS		GENMASK(7, 7)
+#define ALS31300_VOL_LSB_Z_AXIS			GENMASK(11, 8)
+#define ALS31300_VOL_LSB_Y_AXIS			GENMASK(15, 12)
+#define ALS31300_VOL_LSB_X_AXIS			GENMASK(19, 16)
+#define ALS31300_VOL_LSB_INTERRUPT_WRITE	BIT(20)
+#define ALS31300_CUSTOMER_ACCESS	0x35
+
+#define ALS31300_DATA_X_GET(b)		\
+		sign_extend32(FIELD_GET(ALS31300_VOL_MSB_X_AXIS, b[0]) << 4 | \
+			      FIELD_GET(ALS31300_VOL_LSB_X_AXIS, b[1]), 11)
+#define ALS31300_DATA_Y_GET(b)		\
+		sign_extend32(FIELD_GET(ALS31300_VOL_MSB_Y_AXIS, b[0]) << 4 | \
+			      FIELD_GET(ALS31300_VOL_LSB_Y_AXIS, b[1]), 11)
+#define ALS31300_DATA_Z_GET(b)		\
+		sign_extend32(FIELD_GET(ALS31300_VOL_MSB_Z_AXIS, b[0]) << 4 | \
+			      FIELD_GET(ALS31300_VOL_LSB_Z_AXIS, b[1]), 11)
+#define ALS31300_TEMPERATURE_GET(b)	\
+		(FIELD_GET(ALS31300_VOL_MSB_TEMPERATURE, b[0]) << 6 | \
+		 FIELD_GET(ALS31300_VOL_LSB_TEMPERATURE, b[1]))
+
+enum als31300_channels {
+	TEMPERATURE = 0,
+	AXIS_X,
+	AXIS_Y,
+	AXIS_Z,
+};
+
+struct als31300_variant_info {
+	u8 sensitivity;
+};
+
+struct als31300_data {
+	struct device *dev;
+	/* protects power on/off the device and access HW */
+	struct mutex mutex;
+	const struct als31300_variant_info *variant_info;
+	struct regmap *map;
+};
+
+/* The whole measure is split into 2x32-bit registers, we need to read them both at once */
+static int als31300_get_measure(struct als31300_data *data,
+				u16 *t, s16 *x, s16 *y, s16 *z)
+{
+	u32 buf[2];
+	int ret, err;
+
+	guard(mutex)(&data->mutex);
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Loop until data is valid, new data should have the
+	 * ALS31300_VOL_MSB_NEW_DATA bit set to 1.
+	 * Max update rate is 2KHz, wait up to 1ms.
+	 */
+	ret = read_poll_timeout(regmap_bulk_read, err,
+				err || FIELD_GET(ALS31300_VOL_MSB_NEW_DATA, buf[0]),
+				20, USEC_PER_MSEC, false,
+				data->map, ALS31300_VOL_MSB, buf, ARRAY_SIZE(buf));
+	/* Bail out on read_poll_timeout() error */
+	if (ret)
+		goto out;
+
+	/* Bail out on regmap_bulk_read() error */
+	if (err) {
+		dev_err(data->dev, "read data failed, error %d\n", ret);
+		ret = err;
+		goto out;
+	}
+
+	*t = ALS31300_TEMPERATURE_GET(buf);
+	*x = ALS31300_DATA_X_GET(buf);
+	*y = ALS31300_DATA_Y_GET(buf);
+	*z = ALS31300_DATA_Z_GET(buf);
+
+out:
+	pm_runtime_mark_last_busy(data->dev);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int als31300_read_raw(struct iio_dev *indio_dev,
+			     const struct iio_chan_spec *chan, int *val,
+			     int *val2, long mask)
+{
+	struct als31300_data *data = iio_priv(indio_dev);
+	s16 x, y, z;
+	u16 t;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+	case IIO_CHAN_INFO_RAW:
+		ret = als31300_get_measure(data, &t, &x, &y, &z);
+		if (ret)
+			return ret;
+
+		switch (chan->address) {
+		case TEMPERATURE:
+			*val = t;
+			return IIO_VAL_INT;
+		case AXIS_X:
+			*val = x;
+			return IIO_VAL_INT;
+		case AXIS_Y:
+			*val = y;
+			return IIO_VAL_INT;
+		case AXIS_Z:
+			*val = z;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_TEMP:
+			/*
+			 * Fractional part of:
+			 *         1000 * 302 * (value - 1708)
+			 * temp = ----------------------------
+			 *             4096
+			 * to convert temperature in millicelcius.
+			 */
+			*val = MILLI * 302;
+			*val2 = 4096;
+			return IIO_VAL_FRACTIONAL;
+		case IIO_MAGN:
+			/*
+			 * Devices are configured in factory
+			 * with different sensitivities:
+			 * - 500 GAUSS <-> 4 LSB/Gauss
+			 * - 1000 GAUSS <-> 2 LSB/Gauss
+			 * - 2000 GAUSS <-> 1 LSB/Gauss
+			 * with translates by a division of the returned
+			 * value to get Gauss value.
+			 * The sensitivity cannot be read at runtime
+			 * so the value depends on the model compatible
+			 * or device id.
+			 */
+			*val = 1;
+			*val2 = data->variant_info->sensitivity;
+			return IIO_VAL_FRACTIONAL;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_OFFSET:
+		switch (chan->type) {
+		case IIO_TEMP:
+			*val = -1708;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static irqreturn_t als31300_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct als31300_data *data = iio_priv(indio_dev);
+	struct {
+		u16 temperature;
+		s16 channels[3];
+		aligned_s64 timestamp;
+	} scan;
+	s16 x, y, z;
+	int ret;
+	u16 t;
+
+	ret = als31300_get_measure(data, &t, &x, &y, &z);
+	if (ret)
+		goto trigger_out;
+
+	scan.temperature = t;
+	scan.channels[0] = x;
+	scan.channels[1] = y;
+	scan.channels[2] = z;
+	iio_push_to_buffers_with_timestamp(indio_dev, &scan,
+					   pf->timestamp);
+
+trigger_out:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+#define ALS31300_AXIS_CHANNEL(axis, index)				     \
+	{								     \
+		.type = IIO_MAGN,					     \
+		.modified = 1,						     \
+		.channel2 = IIO_MOD_##axis,				     \
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		     \
+				      BIT(IIO_CHAN_INFO_SCALE),		     \
+		.address = index,					     \
+		.scan_index = index,					     \
+		.scan_type = {						     \
+			.sign = 's',					     \
+			.realbits = 12,					     \
+			.storagebits = 16,				     \
+			.endianness = IIO_CPU,				     \
+		},							     \
+	}
+
+static const struct iio_chan_spec als31300_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+		.address = TEMPERATURE,
+		.scan_index = TEMPERATURE,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_CPU,
+		},
+	},
+	ALS31300_AXIS_CHANNEL(X, AXIS_X),
+	ALS31300_AXIS_CHANNEL(Y, AXIS_Y),
+	ALS31300_AXIS_CHANNEL(Z, AXIS_Z),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static const struct iio_info als31300_info = {
+	.read_raw = als31300_read_raw,
+};
+
+static int als31300_set_operating_mode(struct als31300_data *data,
+				       unsigned int val)
+{
+	int ret;
+
+	ret = regmap_update_bits(data->map, ALS31300_VOL_MODE,
+				 ALS31300_VOL_MODE_SLEEP, val);
+	if (ret) {
+		dev_err(data->dev, "failed to set operating mode (%pe)\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	/* The time it takes to exit sleep mode is equivalent to Power-On Delay Time */
+	if (val == ALS31300_VOL_MODE_ACTIVE_MODE)
+		fsleep(600);
+
+	return 0;
+}
+
+static void als31300_power_down(void *data)
+{
+	als31300_set_operating_mode(data, ALS31300_VOL_MODE_SLEEP_MODE);
+}
+
+static const struct iio_buffer_setup_ops als31300_setup_ops = {};
+
+static const unsigned long als31300_scan_masks[] = { GENMASK(3, 0), 0 };
+
+static bool als31300_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg == ALS31300_VOL_MSB || reg == ALS31300_VOL_LSB;
+}
+
+static const struct regmap_config als31300_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 32,
+	.max_register = ALS31300_CUSTOMER_ACCESS,
+	.volatile_reg = als31300_volatile_reg,
+};
+
+static int als31300_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct als31300_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->dev = dev;
+	i2c_set_clientdata(i2c, indio_dev);
+
+	ret = devm_mutex_init(dev, &data->mutex);
+	if (ret)
+		return ret;
+
+	data->variant_info = i2c_get_match_data(i2c);
+	if (!data->variant_info)
+		return -EINVAL;
+
+	data->map = devm_regmap_init_i2c(i2c, &als31300_regmap_config);
+	if (IS_ERR(data->map))
+		return dev_err_probe(dev, PTR_ERR(data->map),
+				     "failed to allocate register map\n");
+
+	ret = devm_regulator_get_enable(dev, "vcc");
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to enable regulator\n");
+
+	ret = als31300_set_operating_mode(data, ALS31300_VOL_MODE_ACTIVE_MODE);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to power on device\n");
+
+	ret = devm_add_action_or_reset(dev, als31300_power_down, data);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to add powerdown action\n");
+
+	indio_dev->info = &als31300_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->name = i2c->name;
+	indio_dev->channels = als31300_channels;
+	indio_dev->num_channels = ARRAY_SIZE(als31300_channels);
+	indio_dev->available_scan_masks = als31300_scan_masks;
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+					      iio_pollfunc_store_time,
+					      als31300_trigger_handler,
+					      &als31300_setup_ops);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "iio triggered buffer setup failed\n");
+
+	ret = pm_runtime_set_active(dev);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
+	pm_runtime_get_noresume(dev);
+	pm_runtime_set_autosuspend_delay(dev, 200);
+	pm_runtime_use_autosuspend(dev);
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "device register failed\n");
+
+	return 0;
+}
+
+static int als31300_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct als31300_data *data = iio_priv(indio_dev);
+
+	return als31300_set_operating_mode(data, ALS31300_VOL_MODE_SLEEP_MODE);
+}
+
+static int als31300_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct als31300_data *data = iio_priv(indio_dev);
+
+	return als31300_set_operating_mode(data, ALS31300_VOL_MODE_ACTIVE_MODE);
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(als31300_pm_ops,
+				 als31300_runtime_suspend, als31300_runtime_resume,
+				 NULL);
+
+static const struct als31300_variant_info al31300_variant_500 = {
+	.sensitivity = 4,
+};
+
+static const struct als31300_variant_info al31300_variant_1000 = {
+	.sensitivity = 2,
+};
+
+static const struct als31300_variant_info al31300_variant_2000 = {
+	.sensitivity = 1,
+};
+
+static const struct i2c_device_id als31300_id[] = {
+	{
+		.name = "als31300-500",
+		.driver_data = (kernel_ulong_t)&al31300_variant_500,
+	},
+	{
+		.name = "als31300-1000",
+		.driver_data = (kernel_ulong_t)&al31300_variant_1000,
+	},
+	{
+		.name = "als31300-2000",
+		.driver_data = (kernel_ulong_t)&al31300_variant_2000,
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, als31300_id);
+
+static const struct of_device_id als31300_of_match[] = {
+	{
+		.compatible = "allegromicro,als31300-500",
+		.data = &al31300_variant_500,
+	},
+	{
+		.compatible = "allegromicro,als31300-1000",
+		.data = &al31300_variant_1000,
+	},
+	{
+		.compatible = "allegromicro,als31300-2000",
+		.data = &al31300_variant_2000,
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, als31300_of_match);
+
+static struct i2c_driver als31300_driver = {
+	.driver	 = {
+		.name = "als31300",
+		.of_match_table = als31300_of_match,
+		.pm = pm_ptr(&als31300_pm_ops),
+	},
+	.probe = als31300_probe,
+	.id_table = als31300_id,
+};
+module_i2c_driver(als31300_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ALS31300 3-D Linear Hall Effect Driver");
+MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");