iio: magnetometer: Add driver for Yamaha YAS530

This adds an IIO magnetometer driver for the Yamaha
YAS530 family of magnetometer/compass chips YAS530,
YAS532 and YAS533.

A quick survey of the source code released by different
vendors reveal that we have these variants in the family
with some deployments listed:

 * YAS529 MS-3C (2005 Samsung Aries)
 * YAS530 MS-3E (2011 Samsung Galaxy S Advance)
 * YAS532 MS-3R (2011 Samsung Galaxy S4)
 * YAS533 MS-3F (Vivo 1633, 1707, V3, Y21L)
 * (YAS534 is a magnetic switch)
 * YAS535 MS-6C
 * YAS536 MS-3W
 * YAS537 MS-3T (2015 Samsung Galaxy S6, Note 5)
 * YAS539 MS-3S (2018 Samsung Galaxy A7 SM-A750FN)

The YAS529 is so significantly different from the
YAS53x variants that it will require its own driver.
The YAS537 and YAS539 have slightly different register
sets but have strong similarities so a common driver
patching this one will probably be reasonable.

The source code for Samsung Galaxy A7's YAS539 is not
that is significantly different from the YAS530 in the
Galaxy S Advance, so I believe we will only need this
one driver with quirks to handle all of them.

The YAS539 is actively announced on Yamaha's devices
site:
https://device.yamaha.com/en/lsi/products/e_compass/

This is a driver written from scratch using buffered
IIO and runtime PM handling regulators and reset.

Thanks to Andy Shevchenko for great help in finding all
the special kernel infrastructure functions and quirks
during review of this driver.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: phone-devel@vger.kernel.org
Cc: Jonathan Bakker <xc-racer2@live.ca>
Link: https://lore.kernel.org/r/20201224120820.1120099-2-linus.walleij@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

3 files changed, 1066 insertions, 0 deletions

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index 1697a8c03506..5d4ffd66032e 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -205,4 +205,19 @@ config SENSORS_RM3100_SPI
 	  To compile this driver as a module, choose M here: the module
 	  will be called rm3100-spi.
 
+config YAMAHA_YAS530
+	tristate "Yamaha YAS530 family of 3-Axis Magnetometers (I2C)"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say Y here to add support for the Yamaha YAS530 series of
+	  3-Axis Magnetometers. Right now YAS530, YAS532 and YAS533 are
+	  fully supported.
+
+	  This driver can also be compiled as a module.
+	  To compile this driver as a module, choose M here: the module
+	  will be called yamaha-yas.
+
 endmenu
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index ba1bc34b82fa..b9f45b7fafc3 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -28,3 +28,5 @@ obj-$(CONFIG_SENSORS_HMC5843_SPI)	+= hmc5843_spi.o
 obj-$(CONFIG_SENSORS_RM3100)		+= rm3100-core.o
 obj-$(CONFIG_SENSORS_RM3100_I2C)	+= rm3100-i2c.o
 obj-$(CONFIG_SENSORS_RM3100_SPI)	+= rm3100-spi.o
+
+obj-$(CONFIG_YAMAHA_YAS530)		+= yamaha-yas530.o
diff --git a/drivers/iio/magnetometer/yamaha-yas530.c b/drivers/iio/magnetometer/yamaha-yas530.c
new file mode 100644
index 000000000000..d46f23d82b3d
--- /dev/null
+++ b/drivers/iio/magnetometer/yamaha-yas530.c
@@ -0,0 +1,1049 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for the Yamaha YAS magnetic sensors, often used in Samsung
+ * mobile phones. While all are not yet handled because of lacking
+ * hardware, expand this driver to handle the different variants:
+ *
+ * YAS530 MS-3E (2011 Samsung Galaxy S Advance)
+ * YAS532 MS-3R (2011 Samsung Galaxy S4)
+ * YAS533 MS-3F (Vivo 1633, 1707, V3, Y21L)
+ * (YAS534 is a magnetic switch, not handled)
+ * YAS535 MS-6C
+ * YAS536 MS-3W
+ * YAS537 MS-3T (2015 Samsung Galaxy S6, Note 5, Xiaomi)
+ * YAS539 MS-3S (2018 Samsung Galaxy A7 SM-A750FN)
+ *
+ * Code functions found in the MPU3050 YAS530 and YAS532 drivers
+ * named "inv_compass" in the Tegra Android kernel tree.
+ * Copyright (C) 2012 InvenSense Corporation
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ */
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/random.h>
+#include <linux/unaligned/be_byteshift.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+/* This register map covers YAS530 and YAS532 but differs in YAS 537 and YAS539 */
+#define YAS5XX_DEVICE_ID		0x80
+#define YAS5XX_ACTUATE_INIT_COIL	0x81
+#define YAS5XX_MEASURE			0x82
+#define YAS5XX_CONFIG			0x83
+#define YAS5XX_MEASURE_INTERVAL		0x84
+#define YAS5XX_OFFSET_X			0x85 /* [-31 .. 31] */
+#define YAS5XX_OFFSET_Y1		0x86 /* [-31 .. 31] */
+#define YAS5XX_OFFSET_Y2		0x87 /* [-31 .. 31] */
+#define YAS5XX_TEST1			0x88
+#define YAS5XX_TEST2			0x89
+#define YAS5XX_CAL			0x90
+#define YAS5XX_MEASURE_DATA		0xB0
+
+/* Bits in the YAS5xx config register */
+#define YAS5XX_CONFIG_INTON		BIT(0) /* Interrupt on? */
+#define YAS5XX_CONFIG_INTHACT		BIT(1) /* Interrupt active high? */
+#define YAS5XX_CONFIG_CCK_MASK		GENMASK(4, 2)
+#define YAS5XX_CONFIG_CCK_SHIFT		2
+
+/* Bits in the measure command register */
+#define YAS5XX_MEASURE_START		BIT(0)
+#define YAS5XX_MEASURE_LDTC		BIT(1)
+#define YAS5XX_MEASURE_FORS		BIT(2)
+#define YAS5XX_MEASURE_DLYMES		BIT(4)
+
+/* Bits in the measure data register */
+#define YAS5XX_MEASURE_DATA_BUSY	BIT(7)
+
+#define YAS530_DEVICE_ID		0x01 /* YAS530 (MS-3E) */
+#define YAS530_VERSION_A		0 /* YAS530 (MS-3E A) */
+#define YAS530_VERSION_B		1 /* YAS530B (MS-3E B) */
+#define YAS530_VERSION_A_COEF		380
+#define YAS530_VERSION_B_COEF		550
+#define YAS530_DATA_BITS		12
+#define YAS530_DATA_CENTER		BIT(YAS530_DATA_BITS - 1)
+#define YAS530_DATA_OVERFLOW		(BIT(YAS530_DATA_BITS) - 1)
+
+#define YAS532_DEVICE_ID		0x02 /* YAS532/YAS533 (MS-3R/F) */
+#define YAS532_VERSION_AB		0 /* YAS532/533 AB (MS-3R/F AB) */
+#define YAS532_VERSION_AC		1 /* YAS532/533 AC (MS-3R/F AC) */
+#define YAS532_VERSION_AB_COEF		1800
+#define YAS532_VERSION_AC_COEF_X	850
+#define YAS532_VERSION_AC_COEF_Y1	750
+#define YAS532_VERSION_AC_COEF_Y2	750
+#define YAS532_DATA_BITS		13
+#define YAS532_DATA_CENTER		BIT(YAS532_DATA_BITS - 1)
+#define YAS532_DATA_OVERFLOW		(BIT(YAS532_DATA_BITS) - 1)
+#define YAS532_20DEGREES		390 /* Looks like Kelvin */
+
+/* These variant IDs are known from code dumps */
+#define YAS537_DEVICE_ID		0x07 /* YAS537 (MS-3T) */
+#define YAS539_DEVICE_ID		0x08 /* YAS539 (MS-3S) */
+
+/* Turn off device regulators etc after 5 seconds of inactivity */
+#define YAS5XX_AUTOSUSPEND_DELAY_MS	5000
+
+struct yas5xx_calibration {
+	/* Linearization calibration x, y1, y2 */
+	s32 r[3];
+	u32 f[3];
+	/* Temperature compensation calibration */
+	s32 Cx, Cy1, Cy2;
+	/* Misc calibration coefficients */
+	s32 a2, a3, a4, a5, a6, a7, a8, a9, k;
+	/* clock divider */
+	u8 dck;
+};
+
+/**
+ * struct yas5xx - state container for the YAS5xx driver
+ * @dev: parent device pointer
+ * @devid: device ID number
+ * @version: device version
+ * @name: device name
+ * @calibration: calibration settings from the OTP storage
+ * @hard_offsets: offsets for each axis measured with initcoil actuated
+ * @orientation: mounting matrix, flipped axis etc
+ * @map: regmap to access the YAX5xx registers over I2C
+ * @regs: the vdd and vddio power regulators
+ * @reset: optional GPIO line used for handling RESET
+ * @lock: locks the magnetometer for exclusive use during a measurement (which
+ * involves several register transactions so the regmap lock is not enough)
+ * so that measurements get serialized in a first-come-first serve manner
+ * @scan: naturally aligned measurements
+ */
+struct yas5xx {
+	struct device *dev;
+	unsigned int devid;
+	unsigned int version;
+	char name[16];
+	struct yas5xx_calibration calibration;
+	u8 hard_offsets[3];
+	struct iio_mount_matrix orientation;
+	struct regmap *map;
+	struct regulator_bulk_data regs[2];
+	struct gpio_desc *reset;
+	struct mutex lock;
+	/*
+	 * The scanout is 4 x 32 bits in CPU endianness.
+	 * Ensure timestamp is naturally aligned
+	 */
+	struct {
+		s32 channels[4];
+		s64 ts __aligned(8);
+	} scan;
+};
+
+/* On YAS530 the x, y1 and y2 values are 12 bits */
+static u16 yas530_extract_axis(u8 *data)
+{
+	u16 val;
+
+	/*
+	 * These are the bits used in a 16bit word:
+	 * 15 14 13 12 11 10 9  8  7  6  5  4  3  2  1  0
+	 *    x  x  x  x  x  x  x  x  x  x  x  x
+	 */
+	val = get_unaligned_be16(&data[0]);
+	val = FIELD_GET(GENMASK(14, 3), val);
+	return val;
+}
+
+/* On YAS532 the x, y1 and y2 values are 13 bits */
+static u16 yas532_extract_axis(u8 *data)
+{
+	u16 val;
+
+	/*
+	 * These are the bits used in a 16bit word:
+	 * 15 14 13 12 11 10 9  8  7  6  5  4  3  2  1  0
+	 *    x  x  x  x  x  x  x  x  x  x  x  x  x
+	 */
+	val = get_unaligned_be16(&data[0]);
+	val = FIELD_GET(GENMASK(14, 2), val);
+	return val;
+}
+
+/**
+ * yas5xx_measure() - Make a measure from the hardware
+ * @yas5xx: The device state
+ * @t: the raw temperature measurement
+ * @x: the raw x axis measurement
+ * @y1: the y1 axis measurement
+ * @y2: the y2 axis measurement
+ * @return: 0 on success or error code
+ */
+static int yas5xx_measure(struct yas5xx *yas5xx, u16 *t, u16 *x, u16 *y1, u16 *y2)
+{
+	unsigned int busy;
+	u8 data[8];
+	int ret;
+	u16 val;
+
+	mutex_lock(&yas5xx->lock);
+	ret = regmap_write(yas5xx->map, YAS5XX_MEASURE, YAS5XX_MEASURE_START);
+	if (ret < 0)
+		goto out_unlock;
+
+	/*
+	 * Typical time to measure 1500 us, max 2000 us so wait min 500 us
+	 * and at most 20000 us (one magnitude more than the datsheet max)
+	 * before timeout.
+	 */
+	ret = regmap_read_poll_timeout(yas5xx->map, YAS5XX_MEASURE_DATA, busy,
+				       !(busy & YAS5XX_MEASURE_DATA_BUSY),
+				       500, 20000);
+	if (ret) {
+		dev_err(yas5xx->dev, "timeout waiting for measurement\n");
+		goto out_unlock;
+	}
+
+	ret = regmap_bulk_read(yas5xx->map, YAS5XX_MEASURE_DATA,
+			       data, sizeof(data));
+	if (ret)
+		goto out_unlock;
+
+	mutex_unlock(&yas5xx->lock);
+
+	switch (yas5xx->devid) {
+	case YAS530_DEVICE_ID:
+		/*
+		 * The t value is 9 bits in big endian format
+		 * These are the bits used in a 16bit word:
+		 * 15 14 13 12 11 10 9  8  7  6  5  4  3  2  1  0
+		 *    x  x  x  x  x  x  x  x  x
+		 */
+		val = get_unaligned_be16(&data[0]);
+		val = FIELD_GET(GENMASK(14, 6), val);
+		*t = val;
+		*x = yas530_extract_axis(&data[2]);
+		*y1 = yas530_extract_axis(&data[4]);
+		*y2 = yas530_extract_axis(&data[6]);
+		break;
+	case YAS532_DEVICE_ID:
+		/*
+		 * The t value is 10 bits in big endian format
+		 * These are the bits used in a 16bit word:
+		 * 15 14 13 12 11 10 9  8  7  6  5  4  3  2  1  0
+		 *    x  x  x  x  x  x  x  x  x  x
+		 */
+		val = get_unaligned_be16(&data[0]);
+		val = FIELD_GET(GENMASK(14, 5), val);
+		*t = val;
+		*x = yas532_extract_axis(&data[2]);
+		*y1 = yas532_extract_axis(&data[4]);
+		*y2 = yas532_extract_axis(&data[6]);
+		break;
+	default:
+		dev_err(yas5xx->dev, "unknown data format\n");
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+
+out_unlock:
+	mutex_unlock(&yas5xx->lock);
+	return ret;
+}
+
+static s32 yas5xx_linearize(struct yas5xx *yas5xx, u16 val, int axis)
+{
+	struct yas5xx_calibration *c = &yas5xx->calibration;
+	static const s32 yas532ac_coef[] = {
+		YAS532_VERSION_AC_COEF_X,
+		YAS532_VERSION_AC_COEF_Y1,
+		YAS532_VERSION_AC_COEF_Y2,
+	};
+	s32 coef;
+
+	/* Select coefficients */
+	switch (yas5xx->devid) {
+	case YAS530_DEVICE_ID:
+		if (yas5xx->version == YAS530_VERSION_A)
+			coef = YAS530_VERSION_A_COEF;
+		else
+			coef = YAS530_VERSION_B_COEF;
+		break;
+	case YAS532_DEVICE_ID:
+		if (yas5xx->version == YAS532_VERSION_AB)
+			coef = YAS532_VERSION_AB_COEF;
+		else
+			/* Elaborate coefficients */
+			coef = yas532ac_coef[axis];
+		break;
+	default:
+		dev_err(yas5xx->dev, "unknown device type\n");
+		return val;
+	}
+	/*
+	 * Linearization formula:
+	 *
+	 * x' = x - (3721 + 50 * f) + (xoffset - r) * c
+	 *
+	 * Where f and r are calibration values, c is a per-device
+	 * and sometimes per-axis coefficient.
+	 */
+	return val - (3721 + 50 * c->f[axis]) +
+		(yas5xx->hard_offsets[axis] - c->r[axis]) * coef;
+}
+
+/**
+ * yas5xx_get_measure() - Measure a sample of all axis and process
+ * @yas5xx: The device state
+ * @to: Temperature out
+ * @xo: X axis out
+ * @yo: Y axis out
+ * @zo: Z axis out
+ * @return: 0 on success or error code
+ *
+ * Returned values are in nanotesla according to some code.
+ */
+static int yas5xx_get_measure(struct yas5xx *yas5xx, s32 *to, s32 *xo, s32 *yo, s32 *zo)
+{
+	struct yas5xx_calibration *c = &yas5xx->calibration;
+	u16 t, x, y1, y2;
+	/* These are "signed x, signed y1 etc */
+	s32 sx, sy1, sy2, sy, sz;
+	int ret;
+
+	/* We first get raw data that needs to be translated to [x,y,z] */
+	ret = yas5xx_measure(yas5xx, &t, &x, &y1, &y2);
+	if (ret)
+		return ret;
+
+	/* Do some linearization if available */
+	sx = yas5xx_linearize(yas5xx, x, 0);
+	sy1 = yas5xx_linearize(yas5xx, y1, 1);
+	sy2 = yas5xx_linearize(yas5xx, y2, 2);
+
+	/*
+	 * Temperature compensation for x, y1, y2 respectively:
+	 *
+	 *          Cx * t
+	 * x' = x - ------
+	 *           100
+	 */
+	sx = sx - (c->Cx * t) / 100;
+	sy1 = sy1 - (c->Cy1 * t) / 100;
+	sy2 = sy2 - (c->Cy2 * t) / 100;
+
+	/*
+	 * Break y1 and y2 into y and z, y1 and y2 are apparently encoding
+	 * y and z.
+	 */
+	sy = sy1 - sy2;
+	sz = -sy1 - sy2;
+
+	/*
+	 * FIXME: convert to Celsius? Just guessing this is given
+	 * as 1/10:s of degrees so multiply by 100 to get millicentigrades.
+	 */
+	*to = t * 100;
+	/*
+	 * Calibrate [x,y,z] with some formulas like this:
+	 *
+	 *            100 * x + a_2 * y + a_3 * z
+	 *  x' = k *  ---------------------------
+	 *                        10
+	 *
+	 *           a_4 * x + a_5 * y + a_6 * z
+	 *  y' = k * ---------------------------
+	 *                        10
+	 *
+	 *           a_7 * x + a_8 * y + a_9 * z
+	 *  z' = k * ---------------------------
+	 *                        10
+	 */
+	*xo = c->k * ((100 * sx + c->a2 * sy + c->a3 * sz) / 10);
+	*yo = c->k * ((c->a4 * sx + c->a5 * sy + c->a6 * sz) / 10);
+	*zo = c->k * ((c->a7 * sx + c->a8 * sy + c->a9 * sz) / 10);
+
+	return 0;
+}
+
+static int yas5xx_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2,
+			   long mask)
+{
+	struct yas5xx *yas5xx = iio_priv(indio_dev);
+	s32 t, x, y, z;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		pm_runtime_get_sync(yas5xx->dev);
+		ret = yas5xx_get_measure(yas5xx, &t, &x, &y, &z);
+		pm_runtime_mark_last_busy(yas5xx->dev);
+		pm_runtime_put_autosuspend(yas5xx->dev);
+		if (ret)
+			return ret;
+		switch (chan->address) {
+		case 0:
+			*val = t;
+			break;
+		case 1:
+			*val = x;
+			break;
+		case 2:
+			*val = y;
+			break;
+		case 3:
+			*val = z;
+			break;
+		default:
+			dev_err(yas5xx->dev, "unknown channel\n");
+			return -EINVAL;
+		}
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->address == 0) {
+			/* Temperature is unscaled */
+			*val = 1;
+			return IIO_VAL_INT;
+		}
+		/*
+		 * The axis values are in nanotesla according to the vendor
+		 * drivers, but is clearly in microtesla according to
+		 * experiments. Since 1 uT = 0.01 Gauss, we need to divide
+		 * by 100000000 (10^8) to get to Gauss from the raw value.
+		 */
+		*val = 1;
+		*val2 = 100000000;
+		return IIO_VAL_FRACTIONAL;
+	default:
+		/* Unknown request */
+		return -EINVAL;
+	}
+}
+
+static void yas5xx_fill_buffer(struct iio_dev *indio_dev)
+{
+	struct yas5xx *yas5xx = iio_priv(indio_dev);
+	s32 t, x, y, z;
+	int ret;
+
+	pm_runtime_get_sync(yas5xx->dev);
+	ret = yas5xx_get_measure(yas5xx, &t, &x, &y, &z);
+	pm_runtime_mark_last_busy(yas5xx->dev);
+	pm_runtime_put_autosuspend(yas5xx->dev);
+	if (ret) {
+		dev_err(yas5xx->dev, "error refilling buffer\n");
+		return;
+	}
+	yas5xx->scan.channels[0] = t;
+	yas5xx->scan.channels[1] = x;
+	yas5xx->scan.channels[2] = y;
+	yas5xx->scan.channels[3] = z;
+	iio_push_to_buffers_with_timestamp(indio_dev, &yas5xx->scan,
+					   iio_get_time_ns(indio_dev));
+}
+
+static irqreturn_t yas5xx_handle_trigger(int irq, void *p)
+{
+	const struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+
+	yas5xx_fill_buffer(indio_dev);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+
+static const struct iio_mount_matrix *
+yas5xx_get_mount_matrix(const struct iio_dev *indio_dev,
+			const struct iio_chan_spec *chan)
+{
+	struct yas5xx *yas5xx = iio_priv(indio_dev);
+
+	return &yas5xx->orientation;
+}
+
+static const struct iio_chan_spec_ext_info yas5xx_ext_info[] = {
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, yas5xx_get_mount_matrix),
+	{ }
+};
+
+#define YAS5XX_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),			\
+		.ext_info = yas5xx_ext_info,				\
+		.address = index,					\
+		.scan_index = index,					\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 32,					\
+			.storagebits = 32,				\
+			.endianness = IIO_CPU,				\
+		},							\
+	}
+
+static const struct iio_chan_spec yas5xx_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.address = 0,
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 32,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
+	},
+	YAS5XX_AXIS_CHANNEL(X, 1),
+	YAS5XX_AXIS_CHANNEL(Y, 2),
+	YAS5XX_AXIS_CHANNEL(Z, 3),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static const unsigned long yas5xx_scan_masks[] = { GENMASK(3, 0), 0 };
+
+static const struct iio_info yas5xx_info = {
+	.read_raw = &yas5xx_read_raw,
+};
+
+static bool yas5xx_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg == YAS5XX_ACTUATE_INIT_COIL ||
+		reg == YAS5XX_MEASURE ||
+		(reg >= YAS5XX_MEASURE_DATA && reg <= YAS5XX_MEASURE_DATA + 8);
+}
+
+/* TODO: enable regmap cache, using mark dirty and sync at runtime resume */
+static const struct regmap_config yas5xx_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = 0xff,
+	.volatile_reg = yas5xx_volatile_reg,
+};
+
+/**
+ * yas53x_extract_calibration() - extracts the a2-a9 and k calibration
+ * @data: the bitfield to use
+ * @c: the calibration to populate
+ */
+static void yas53x_extract_calibration(u8 *data, struct yas5xx_calibration *c)
+{
+	u64 val = get_unaligned_be64(data);
+
+	/*
+	 * Bitfield layout for the axis calibration data, for factor
+	 * a2 = 2 etc, k = k, c = clock divider
+	 *
+	 * n   7 6 5 4 3 2 1 0
+	 * 0 [ 2 2 2 2 2 2 3 3 ] bits 63 .. 56
+	 * 1 [ 3 3 4 4 4 4 4 4 ] bits 55 .. 48
+	 * 2 [ 5 5 5 5 5 5 6 6 ] bits 47 .. 40
+	 * 3 [ 6 6 6 6 7 7 7 7 ] bits 39 .. 32
+	 * 4 [ 7 7 7 8 8 8 8 8 ] bits 31 .. 24
+	 * 5 [ 8 9 9 9 9 9 9 9 ] bits 23 .. 16
+	 * 6 [ 9 k k k k k c c ] bits 15 .. 8
+	 * 7 [ c x x x x x x x ] bits  7 .. 0
+	 */
+	c->a2 = FIELD_GET(GENMASK_ULL(63, 58), val) - 32;
+	c->a3 = FIELD_GET(GENMASK_ULL(57, 54), val) - 8;
+	c->a4 = FIELD_GET(GENMASK_ULL(53, 48), val) - 32;
+	c->a5 = FIELD_GET(GENMASK_ULL(47, 42), val) + 38;
+	c->a6 = FIELD_GET(GENMASK_ULL(41, 36), val) - 32;
+	c->a7 = FIELD_GET(GENMASK_ULL(35, 29), val) - 64;
+	c->a8 = FIELD_GET(GENMASK_ULL(28, 23), val) - 32;
+	c->a9 = FIELD_GET(GENMASK_ULL(22, 15), val);
+	c->k = FIELD_GET(GENMASK_ULL(14, 10), val) + 10;
+	c->dck = FIELD_GET(GENMASK_ULL(9, 7), val);
+}
+
+static int yas530_get_calibration_data(struct yas5xx *yas5xx)
+{
+	struct yas5xx_calibration *c = &yas5xx->calibration;
+	u8 data[16];
+	u32 val;
+	int ret;
+
+	/* Dummy read, first read is ALWAYS wrong */
+	ret = regmap_bulk_read(yas5xx->map, YAS5XX_CAL, data, sizeof(data));
+	if (ret)
+		return ret;
+
+	/* Actual calibration readout */
+	ret = regmap_bulk_read(yas5xx->map, YAS5XX_CAL, data, sizeof(data));
+	if (ret)
+		return ret;
+	dev_dbg(yas5xx->dev, "calibration data: %*ph\n", 14, data);
+
+	add_device_randomness(data, sizeof(data));
+	yas5xx->version = data[15] & GENMASK(1, 0);
+
+	/* Extract the calibration from the bitfield */
+	c->Cx = data[0] * 6 - 768;
+	c->Cy1 = data[1] * 6 - 768;
+	c->Cy2 = data[2] * 6 - 768;
+	yas53x_extract_calibration(&data[3], c);
+
+	/*
+	 * Extract linearization:
+	 * Linearization layout in the 32 bits at byte 11:
+	 * The r factors are 6 bit values where bit 5 is the sign
+	 *
+	 * n    7  6  5  4  3  2  1  0
+	 * 0 [ xx xx xx r0 r0 r0 r0 r0 ] bits 31 .. 24
+	 * 1 [ r0 f0 f0 r1 r1 r1 r1 r1 ] bits 23 .. 16
+	 * 2 [ r1 f1 f1 r2 r2 r2 r2 r2 ] bits 15 .. 8
+	 * 3 [ r2 f2 f2 xx xx xx xx xx ] bits  7 .. 0
+	 */
+	val = get_unaligned_be32(&data[11]);
+	c->f[0] = FIELD_GET(GENMASK(22, 21), val);
+	c->f[1] = FIELD_GET(GENMASK(14, 13), val);
+	c->f[2] = FIELD_GET(GENMASK(6, 5), val);
+	c->r[0] = sign_extend32(FIELD_GET(GENMASK(28, 23), val), 5);
+	c->r[1] = sign_extend32(FIELD_GET(GENMASK(20, 15), val), 5);
+	c->r[2] = sign_extend32(FIELD_GET(GENMASK(12, 7), val), 5);
+	return 0;
+}
+
+static int yas532_get_calibration_data(struct yas5xx *yas5xx)
+{
+	struct yas5xx_calibration *c = &yas5xx->calibration;
+	u8 data[14];
+	u32 val;
+	int ret;
+
+	/* Dummy read, first read is ALWAYS wrong */
+	ret = regmap_bulk_read(yas5xx->map, YAS5XX_CAL, data, sizeof(data));
+	if (ret)
+		return ret;
+	/* Actual calibration readout */
+	ret = regmap_bulk_read(yas5xx->map, YAS5XX_CAL, data, sizeof(data));
+	if (ret)
+		return ret;
+	dev_dbg(yas5xx->dev, "calibration data: %*ph\n", 14, data);
+
+	/* Sanity check, is this all zeroes? */
+	if (memchr_inv(data, 0x00, 13)) {
+		if (!(data[13] & BIT(7)))
+			dev_warn(yas5xx->dev, "calibration is blank!\n");
+	}
+
+	add_device_randomness(data, sizeof(data));
+	/* Only one bit of version info reserved here as far as we know */
+	yas5xx->version = data[13] & BIT(0);
+
+	/* Extract calibration from the bitfield */
+	c->Cx = data[0] * 10 - 1280;
+	c->Cy1 = data[1] * 10 - 1280;
+	c->Cy2 = data[2] * 10 - 1280;
+	yas53x_extract_calibration(&data[3], c);
+	/*
+	 * Extract linearization:
+	 * Linearization layout in the 32 bits at byte 10:
+	 * The r factors are 6 bit values where bit 5 is the sign
+	 *
+	 * n    7  6  5  4  3  2  1  0
+	 * 0 [ xx r0 r0 r0 r0 r0 r0 f0 ] bits 31 .. 24
+	 * 1 [ f0 r1 r1 r1 r1 r1 r1 f1 ] bits 23 .. 16
+	 * 2 [ f1 r2 r2 r2 r2 r2 r2 f2 ] bits 15 .. 8
+	 * 3 [ f2 xx xx xx xx xx xx xx ] bits  7 .. 0
+	 */
+	val = get_unaligned_be32(&data[10]);
+	c->f[0] = FIELD_GET(GENMASK(24, 23), val);
+	c->f[1] = FIELD_GET(GENMASK(16, 15), val);
+	c->f[2] = FIELD_GET(GENMASK(8, 7), val);
+	c->r[0] = sign_extend32(FIELD_GET(GENMASK(30, 25), val), 5);
+	c->r[1] = sign_extend32(FIELD_GET(GENMASK(22, 17), val), 5);
+	c->r[2] = sign_extend32(FIELD_GET(GENMASK(14, 7), val), 5);
+
+	return 0;
+}
+
+static void yas5xx_dump_calibration(struct yas5xx *yas5xx)
+{
+	struct yas5xx_calibration *c = &yas5xx->calibration;
+
+	dev_dbg(yas5xx->dev, "f[] = [%d, %d, %d]\n",
+		c->f[0], c->f[1], c->f[2]);
+	dev_dbg(yas5xx->dev, "r[] = [%d, %d, %d]\n",
+		c->r[0], c->r[1], c->r[2]);
+	dev_dbg(yas5xx->dev, "Cx = %d\n", c->Cx);
+	dev_dbg(yas5xx->dev, "Cy1 = %d\n", c->Cy1);
+	dev_dbg(yas5xx->dev, "Cy2 = %d\n", c->Cy2);
+	dev_dbg(yas5xx->dev, "a2 = %d\n", c->a2);
+	dev_dbg(yas5xx->dev, "a3 = %d\n", c->a3);
+	dev_dbg(yas5xx->dev, "a4 = %d\n", c->a4);
+	dev_dbg(yas5xx->dev, "a5 = %d\n", c->a5);
+	dev_dbg(yas5xx->dev, "a6 = %d\n", c->a6);
+	dev_dbg(yas5xx->dev, "a7 = %d\n", c->a7);
+	dev_dbg(yas5xx->dev, "a8 = %d\n", c->a8);
+	dev_dbg(yas5xx->dev, "a9 = %d\n", c->a9);
+	dev_dbg(yas5xx->dev, "k = %d\n", c->k);
+	dev_dbg(yas5xx->dev, "dck = %d\n", c->dck);
+}
+
+static int yas5xx_set_offsets(struct yas5xx *yas5xx, s8 ox, s8 oy1, s8 oy2)
+{
+	int ret;
+
+	ret = regmap_write(yas5xx->map, YAS5XX_OFFSET_X, ox);
+	if (ret)
+		return ret;
+	ret = regmap_write(yas5xx->map, YAS5XX_OFFSET_Y1, oy1);
+	if (ret)
+		return ret;
+	return regmap_write(yas5xx->map, YAS5XX_OFFSET_Y2, oy2);
+}
+
+static s8 yas5xx_adjust_offset(s8 old, int bit, u16 center, u16 measure)
+{
+	if (measure > center)
+		return old + BIT(bit);
+	if (measure < center)
+		return old - BIT(bit);
+	return old;
+}
+
+static int yas5xx_meaure_offsets(struct yas5xx *yas5xx)
+{
+	int ret;
+	u16 center;
+	u16 t, x, y1, y2;
+	s8 ox, oy1, oy2;
+	int i;
+
+	/* Actuate the init coil and measure offsets */
+	ret = regmap_write(yas5xx->map, YAS5XX_ACTUATE_INIT_COIL, 0);
+	if (ret)
+		return ret;
+
+	/* When the initcoil is active this should be around the center */
+	switch (yas5xx->devid) {
+	case YAS530_DEVICE_ID:
+		center = YAS530_DATA_CENTER;
+		break;
+	case YAS532_DEVICE_ID:
+		center = YAS532_DATA_CENTER;
+		break;
+	default:
+		dev_err(yas5xx->dev, "unknown device type\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * We set offsets in the interval +-31 by iterating
+	 * +-16, +-8, +-4, +-2, +-1 adjusting the offsets each
+	 * time, then writing the final offsets into the
+	 * registers.
+	 *
+	 * NOTE: these offsets are NOT in the same unit or magnitude
+	 * as the values for [x, y1, y2]. The value is +/-31
+	 * but the effect on the raw values is much larger.
+	 * The effect of the offset is to bring the measure
+	 * rougly to the center.
+	 */
+	ox = 0;
+	oy1 = 0;
+	oy2 = 0;
+
+	for (i = 4; i >= 0; i--) {
+		ret = yas5xx_set_offsets(yas5xx, ox, oy1, oy2);
+		if (ret)
+			return ret;
+
+		ret = yas5xx_measure(yas5xx, &t, &x, &y1, &y2);
+		if (ret)
+			return ret;
+		dev_dbg(yas5xx->dev, "measurement %d: x=%d, y1=%d, y2=%d\n",
+			5-i, x, y1, y2);
+
+		ox = yas5xx_adjust_offset(ox, i, center, x);
+		oy1 = yas5xx_adjust_offset(oy1, i, center, y1);
+		oy2 = yas5xx_adjust_offset(oy2, i, center, y2);
+	}
+
+	/* Needed for calibration algorithm */
+	yas5xx->hard_offsets[0] = ox;
+	yas5xx->hard_offsets[1] = oy1;
+	yas5xx->hard_offsets[2] = oy2;
+	ret = yas5xx_set_offsets(yas5xx, ox, oy1, oy2);
+	if (ret)
+		return ret;
+
+	dev_info(yas5xx->dev, "discovered hard offsets: x=%d, y1=%d, y2=%d\n",
+		 ox, oy1, oy2);
+	return 0;
+}
+
+static int yas5xx_power_on(struct yas5xx *yas5xx)
+{
+	unsigned int val;
+	int ret;
+
+	/* Zero the test registers */
+	ret = regmap_write(yas5xx->map, YAS5XX_TEST1, 0);
+	if (ret)
+		return ret;
+	ret = regmap_write(yas5xx->map, YAS5XX_TEST2, 0);
+	if (ret)
+		return ret;
+
+	/* Set up for no interrupts, calibrated clock divider */
+	val = FIELD_PREP(YAS5XX_CONFIG_CCK_MASK, yas5xx->calibration.dck);
+	ret = regmap_write(yas5xx->map, YAS5XX_CONFIG, val);
+	if (ret)
+		return ret;
+
+	/* Measure interval 0 (back-to-back?)  */
+	return regmap_write(yas5xx->map, YAS5XX_MEASURE_INTERVAL, 0);
+}
+
+static int yas5xx_probe(struct i2c_client *i2c,
+			const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct device *dev = &i2c->dev;
+	struct yas5xx *yas5xx;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*yas5xx));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	yas5xx = iio_priv(indio_dev);
+	i2c_set_clientdata(i2c, indio_dev);
+	yas5xx->dev = dev;
+	mutex_init(&yas5xx->lock);
+
+	ret = iio_read_mount_matrix(dev, "mount-matrix", &yas5xx->orientation);
+	if (ret)
+		return ret;
+
+	yas5xx->regs[0].supply = "vdd";
+	yas5xx->regs[1].supply = "iovdd";
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(yas5xx->regs),
+				      yas5xx->regs);
+	if (ret)
+		return dev_err_probe(dev, ret, "cannot get regulators\n");
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(yas5xx->regs), yas5xx->regs);
+	if (ret) {
+		dev_err(dev, "cannot enable regulators\n");
+		return ret;
+	}
+
+	/* See comment in runtime resume callback */
+	usleep_range(31000, 40000);
+
+	/* This will take the device out of reset if need be */
+	yas5xx->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(yas5xx->reset)) {
+		ret = dev_err_probe(dev, PTR_ERR(yas5xx->reset),
+				    "failed to get reset line\n");
+		goto reg_off;
+	}
+
+	yas5xx->map = devm_regmap_init_i2c(i2c, &yas5xx_regmap_config);
+	if (IS_ERR(yas5xx->map)) {
+		dev_err(dev, "failed to allocate register map\n");
+		ret = PTR_ERR(yas5xx->map);
+		goto assert_reset;
+	}
+
+	ret = regmap_read(yas5xx->map, YAS5XX_DEVICE_ID, &yas5xx->devid);
+	if (ret)
+		goto assert_reset;
+
+	switch (yas5xx->devid) {
+	case YAS530_DEVICE_ID:
+		ret = yas530_get_calibration_data(yas5xx);
+		if (ret)
+			goto assert_reset;
+		dev_info(dev, "detected YAS530 MS-3E %s",
+			 yas5xx->version ? "B" : "A");
+		strncpy(yas5xx->name, "yas530", sizeof(yas5xx->name));
+		break;
+	case YAS532_DEVICE_ID:
+		ret = yas532_get_calibration_data(yas5xx);
+		if (ret)
+			goto assert_reset;
+		dev_info(dev, "detected YAS532/YAS533 MS-3R/F %s",
+			 yas5xx->version ? "AC" : "AB");
+		strncpy(yas5xx->name, "yas532", sizeof(yas5xx->name));
+		break;
+	default:
+		dev_err(dev, "unhandled device ID %02x\n", yas5xx->devid);
+		goto assert_reset;
+	}
+
+	yas5xx_dump_calibration(yas5xx);
+	ret = yas5xx_power_on(yas5xx);
+	if (ret)
+		goto assert_reset;
+	ret = yas5xx_meaure_offsets(yas5xx);
+	if (ret)
+		goto assert_reset;
+
+	indio_dev->info = &yas5xx_info;
+	indio_dev->available_scan_masks = yas5xx_scan_masks;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->name = yas5xx->name;
+	indio_dev->channels = yas5xx_channels;
+	indio_dev->num_channels = ARRAY_SIZE(yas5xx_channels);
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 yas5xx_handle_trigger,
+					 NULL);
+	if (ret) {
+		dev_err(dev, "triggered buffer setup failed\n");
+		goto assert_reset;
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(dev, "device register failed\n");
+		goto cleanup_buffer;
+	}
+
+	/* Take runtime PM online */
+	pm_runtime_get_noresume(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
+	pm_runtime_set_autosuspend_delay(dev, YAS5XX_AUTOSUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_put(dev);
+
+	return 0;
+
+cleanup_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+assert_reset:
+	gpiod_set_value_cansleep(yas5xx->reset, 1);
+reg_off:
+	regulator_bulk_disable(ARRAY_SIZE(yas5xx->regs), yas5xx->regs);
+
+	return ret;
+}
+
+static int yas5xx_remove(struct i2c_client *i2c)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(i2c);
+	struct yas5xx *yas5xx = iio_priv(indio_dev);
+	struct device *dev = &i2c->dev;
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	/*
+	 * Now we can't get any more reads from the device, which would
+	 * also call pm_runtime* functions and race with our disable
+	 * code. Disable PM runtime in orderly fashion and power down.
+	 */
+	pm_runtime_get_sync(dev);
+	pm_runtime_put_noidle(dev);
+	pm_runtime_disable(dev);
+	gpiod_set_value_cansleep(yas5xx->reset, 1);
+	regulator_bulk_disable(ARRAY_SIZE(yas5xx->regs), yas5xx->regs);
+
+	return 0;
+}
+
+static int __maybe_unused yas5xx_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct yas5xx *yas5xx = iio_priv(indio_dev);
+
+	gpiod_set_value_cansleep(yas5xx->reset, 1);
+	regulator_bulk_disable(ARRAY_SIZE(yas5xx->regs), yas5xx->regs);
+
+	return 0;
+}
+
+static int __maybe_unused yas5xx_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct yas5xx *yas5xx = iio_priv(indio_dev);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(yas5xx->regs), yas5xx->regs);
+	if (ret) {
+		dev_err(dev, "cannot enable regulators\n");
+		return ret;
+	}
+
+	/*
+	 * The YAS530 datasheet says TVSKW is up to 30 ms, after that 1 ms
+	 * for all voltages to settle. The YAS532 is 10ms then 4ms for the
+	 * I2C to come online. Let's keep it safe and put this at 31ms.
+	 */
+	usleep_range(31000, 40000);
+	gpiod_set_value_cansleep(yas5xx->reset, 0);
+
+	ret = yas5xx_power_on(yas5xx);
+	if (ret) {
+		dev_err(dev, "cannot power on\n");
+		goto out_reset;
+	}
+
+	return 0;
+
+out_reset:
+	gpiod_set_value_cansleep(yas5xx->reset, 1);
+	regulator_bulk_disable(ARRAY_SIZE(yas5xx->regs), yas5xx->regs);
+
+	return ret;
+}
+
+static const struct dev_pm_ops yas5xx_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(yas5xx_runtime_suspend,
+			   yas5xx_runtime_resume, NULL)
+};
+
+static const struct i2c_device_id yas5xx_id[] = {
+	{"yas530", },
+	{"yas532", },
+	{"yas533", },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, yas5xx_id);
+
+static const struct of_device_id yas5xx_of_match[] = {
+	{ .compatible = "yamaha,yas530", },
+	{ .compatible = "yamaha,yas532", },
+	{ .compatible = "yamaha,yas533", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, yas5xx_of_match);
+
+static struct i2c_driver yas5xx_driver = {
+	.driver	 = {
+		.name	= "yas5xx",
+		.of_match_table = yas5xx_of_match,
+		.pm = &yas5xx_dev_pm_ops,
+	},
+	.probe	  = yas5xx_probe,
+	.remove	  = yas5xx_remove,
+	.id_table = yas5xx_id,
+};
+module_i2c_driver(yas5xx_driver);
+
+MODULE_DESCRIPTION("Yamaha YAS53x 3-axis magnetometer driver");
+MODULE_AUTHOR("Linus Walleij");
+MODULE_LICENSE("GPL v2");