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.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/iio/magnetometer/Kconfig    |  13 +
 drivers/iio/magnetometer/Makefile   |   1 +
 drivers/iio/magnetometer/als31300.c | 495 ++++++++++++++++++++++++++++++++++++
 3 files changed, 509 insertions(+)

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index 8eb718f5e50f3591082d33618b680ea22608fde8..e7adc11049d6f71b76da4569be4756e65f9dfd28 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -52,6 +52,19 @@ 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 ec5c46fbf999b6403593de2c425079cf69a29cac..3e4c2ecd9adf865025d169a0d1d5feffd012e2f3 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 0000000000000000000000000000000000000000..f5eb0cdffe105108d151767c03ea26b0313551c8
--- /dev/null
+++ b/drivers/iio/magnetometer/als31300.c
@@ -0,0 +1,495 @@
+// 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/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.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 2x32bit 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)
+{
+	unsigned int count = 0;
+	u32 buf[2];
+	int ret;
+
+	guard(mutex)(&data->mutex);
+
+	ret = pm_runtime_resume_and_get(data->dev);
+	if (ret)
+		return ret;
+
+	/* Max update rate is 2KHz, wait up to 1ms */
+	while (count < 50) {
+		/* Read Data */
+		ret = regmap_bulk_read(data->map, ALS31300_VOL_MSB, buf, 2);
+		if (ret) {
+			dev_err(data->dev, "read data failed, error %d\n", ret);
+			goto out;
+		}
+
+		/* Check if data is valid, happens right after getting out of sleep mode */
+		if (FIELD_GET(ALS31300_VOL_MSB_NEW_DATA, buf[0]))
+			break;
+
+		usleep_range(10, 20);
+		++count;
+	}
+
+	if (count >= 50) {
+		ret = -ETIMEDOUT;
+		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 = 1000 * 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 sensisitivity 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;
+	} __packed 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)
+		usleep_range(600, 650);
+
+	return ret;
+}
+
+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);
+
+	mutex_init(&data->mutex);
+
+	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) {
+		dev_err(dev, "iio triggered buffer setup failed\n");
+		return ret;
+	}
+
+	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>");

-- 
2.34.1

Mon, Oct 21, 2024 at 02:38:55PM +0200, Neil Armstrong kirjoitti:
> 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.

...

Some headers are missing...

> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>

+ pm.h

> +#include <linux/pm_runtime.h>

> +#include <linux/regulator/consumer.h>

+ types.h

...

> +#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]))

These and in the code seems like you make a home grown endianes conversion.
I suppose all of them have to be __beXX with the respective masks that cover
all the bits.

> +static int als31300_get_measure(struct als31300_data *data,
> +				u16 *t, s16 *x, s16 *y, s16 *z)
> +{
> +	unsigned int count = 0;
> +	u32 buf[2];

Shouldn't this be __be64 buf?

> +	int ret;
> +
> +	guard(mutex)(&data->mutex);
> +
> +	ret = pm_runtime_resume_and_get(data->dev);
> +	if (ret)
> +		return ret;

> +	/* Max update rate is 2KHz, wait up to 1ms */
> +	while (count < 50) {
> +		/* Read Data */
> +		ret = regmap_bulk_read(data->map, ALS31300_VOL_MSB, buf, 2);

At bare minimum ARRAY_SIZE(), but see above, I think it should use the respective type.

> +		if (ret) {
> +			dev_err(data->dev, "read data failed, error %d\n", ret);
> +			goto out;
> +		}
> +
> +		/* Check if data is valid, happens right after getting out of sleep mode */
> +		if (FIELD_GET(ALS31300_VOL_MSB_NEW_DATA, buf[0]))
> +			break;
> +
> +		usleep_range(10, 20);
> +		++count;
> +	}
> +
> +	if (count >= 50) {
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}

This one of the longest variant of implementing

	do {
		...
	} while (!FIELD_GET(...) && --count)

But you also may consider something from iopoll.h (I don't remember if we have
regmap_read_poll_timeout() for bulk transfers.

> +	*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);

Last discussion with Rafael on the topic of the above puts a question mark to
all these cases when runtime PM idle callback has not been implemented.

Shouldn't this be simply 

	pm_runtime_put(data->dev);

?

> +	return ret;
> +}

...

> +	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 = 1000 * 302;

MILLI from units.h ?

> +			*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 sensisitivity 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;
> +		}

...

> +	struct {
> +		u16 temperature;
> +		s16 channels[3];
> +		aligned_s64 timestamp;
> +	} __packed scan;

Why __packed?

...

> +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)
> +		usleep_range(600, 650);
> +
> +	return ret;

	return 0;

> +}

...

> +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);

> +	mutex_init(&data->mutex);

Why not devm_mutex_init()? How does this being cleaned up?

> +	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) {
> +		dev_err(dev, "iio triggered buffer setup failed\n");
> +		return ret;

Why not return dev_err_probe(...);

> +	}
> +
> +	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;
> +}

-- 
With Best Regards,
Andy Shevchenko

Hi,

On 26/10/2024 23:17, Andy Shevchenko wrote:
> Mon, Oct 21, 2024 at 02:38:55PM +0200, Neil Armstrong kirjoitti:
>> 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.
> 
> ...
> 
> Some headers are missing...
> 
>> +#include <linux/bitfield.h>
>> +#include <linux/bits.h>
>> +#include <linux/delay.h>
>> +#include <linux/module.h>
>> +#include <linux/i2c.h>
>> +#include <linux/regmap.h>
> 
> + pm.h
> 
>> +#include <linux/pm_runtime.h>
> 
>> +#include <linux/regulator/consumer.h>
> 
> + types.h

Ack

> 
> ...
> 
>> +#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]))
> 
> These and in the code seems like you make a home grown endianes conversion.
> I suppose all of them have to be __beXX with the respective masks that cover
> all the bits.

This has nothing do to with endianess conversion, the bits of the 4 channels
are split on 2 registers, look at the defines.

> 
>> +static int als31300_get_measure(struct als31300_data *data,
>> +				u16 *t, s16 *x, s16 *y, s16 *z)
>> +{
>> +	unsigned int count = 0;
>> +	u32 buf[2];
> 
> Shouldn't this be __be64 buf?

No this is 2 separate registers with different fields, not a single 64bit big-endian register

> 
>> +	int ret;
>> +
>> +	guard(mutex)(&data->mutex);
>> +
>> +	ret = pm_runtime_resume_and_get(data->dev);
>> +	if (ret)
>> +		return ret;
> 
>> +	/* Max update rate is 2KHz, wait up to 1ms */
>> +	while (count < 50) {
>> +		/* Read Data */
>> +		ret = regmap_bulk_read(data->map, ALS31300_VOL_MSB, buf, 2);
> 
> At bare minimum ARRAY_SIZE(), but see above, I think it should use the respective type.

I'll use ARRAY_SIZE

> 
>> +		if (ret) {
>> +			dev_err(data->dev, "read data failed, error %d\n", ret);
>> +			goto out;
>> +		}
>> +
>> +		/* Check if data is valid, happens right after getting out of sleep mode */
>> +		if (FIELD_GET(ALS31300_VOL_MSB_NEW_DATA, buf[0]))
>> +			break;
>> +
>> +		usleep_range(10, 20);
>> +		++count;
>> +	}
>> +
>> +	if (count >= 50) {
>> +		ret = -ETIMEDOUT;
>> +		goto out;
>> +	}
> 
> This one of the longest variant of implementing
> 
> 	do {
> 		...
> 	} while (!FIELD_GET(...) && --count)
> 
> But you also may consider something from iopoll.h (I don't remember if we have
> regmap_read_poll_timeout() for bulk transfers.

There's no poll for bulk read, I'll try using an IOPOLL function

> 
>> +	*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);
> 
> Last discussion with Rafael on the topic of the above puts a question mark to
> all these cases when runtime PM idle callback has not been implemented.
> 
> Shouldn't this be simply
> 
> 	pm_runtime_put(data->dev);
> 
> ?

Probably, I just used the same schema as other similar IIO drivers

> 
>> +	return ret;
>> +}
> 
> ...
> 
>> +	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 = 1000 * 302;
> 
> MILLI from units.h ?

Well, sure, but it's still 1000, should I also define ONE to 1 and so on ?

> 
>> +			*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 sensisitivity 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;
>> +		}
> 
> ...
> 
>> +	struct {
>> +		u16 temperature;
>> +		s16 channels[3];
>> +		aligned_s64 timestamp;
>> +	} __packed scan;
> 
> Why __packed?

Probably unneeded, will drop

> 
> ...
> 
>> +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)
>> +		usleep_range(600, 650);
>> +
>> +	return ret;
> 
> 	return 0;

It's the same but ok

> 
>> +}
> 
> ...
> 
>> +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);
> 
>> +	mutex_init(&data->mutex);
> 
> Why not devm_mutex_init()? How does this being cleaned up?

Indeed, good catch

> 
>> +	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) {
>> +		dev_err(dev, "iio triggered buffer setup failed\n");
>> +		return ret;
> 
> Why not return dev_err_probe(...);

Sure

> 
>> +	}
>> +
>> +	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;
>> +}
> 

Thanks,
Neil