drivers/iio/magnetometer/mmc35240.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * MMC35240 - MEMSIC 3-axis Magnetic Sensor
  *
  * Copyright (c) 2015, Intel Corporation.
  *
  * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
  *
  * TODO: offset, ACPI, continuous measurement mode, PM
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/regmap.h>
 #include <linux/acpi.h>
 #include <linux/pm.h>

 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>

 #define MMC35240_DRV_NAME "mmc35240"
 #define MMC35240_REGMAP_NAME "mmc35240_regmap"

 #define MMC35240_REG_XOUT_L	0x00
 #define MMC35240_REG_XOUT_H	0x01
 #define MMC35240_REG_YOUT_L	0x02
 #define MMC35240_REG_YOUT_H	0x03
 #define MMC35240_REG_ZOUT_L	0x04
 #define MMC35240_REG_ZOUT_H	0x05

 #define MMC35240_REG_STATUS	0x06
 #define MMC35240_REG_CTRL0	0x07
 #define MMC35240_REG_CTRL1	0x08

 #define MMC35240_REG_ID		0x20

 #define MMC35240_STATUS_MEAS_DONE_BIT	BIT(0)

 #define MMC35240_CTRL0_REFILL_BIT	BIT(7)
 #define MMC35240_CTRL0_RESET_BIT	BIT(6)
 #define MMC35240_CTRL0_SET_BIT		BIT(5)
 #define MMC35240_CTRL0_CMM_BIT		BIT(1)
 #define MMC35240_CTRL0_TM_BIT		BIT(0)

 /* output resolution bits */
 #define MMC35240_CTRL1_BW0_BIT		BIT(0)
 #define MMC35240_CTRL1_BW1_BIT		BIT(1)

 #define MMC35240_CTRL1_BW_MASK	 (MMC35240_CTRL1_BW0_BIT | \
 		 MMC35240_CTRL1_BW1_BIT)
 #define MMC35240_CTRL1_BW_SHIFT		0

 #define MMC35240_WAIT_CHARGE_PUMP	50000	/* us */
 #define MMC35240_WAIT_SET_RESET		1000	/* us */

 /*
  * Memsic OTP process code piece is put here for reference:
  *
  * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
  * 1) For X axis, the COEFFICIENT is always 1.
  * 2) For Y axis, the COEFFICIENT is as below:
  *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
  *                                   (reg_data[2] >> 4)) + 1.0;
  * 3) For Z axis, the COEFFICIENT is as below:
  *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
  * We implemented the OTP logic into driver.
  */

 /* scale = 1000 here for Y otp */
 #define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)

 /* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
 #define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)

 #define MMC35240_X_COEFF(x)	(x)
 #define MMC35240_Y_COEFF(y)	(y + 1000)
 #define MMC35240_Z_COEFF(z)	(z + 13500)

 #define MMC35240_OTP_START_ADDR		0x1B

 enum mmc35240_resolution {
 	MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
 	MMC35240_16_BITS_FAST,     /* 4.08 ms */
 	MMC35240_14_BITS,          /* 2.16 ms */
 	MMC35240_12_BITS,          /* 1.20 ms */
 };

 enum mmc35240_axis {
 	AXIS_X = 0,
 	AXIS_Y,
 	AXIS_Z,
 };

 static const struct {
 	int sens[3]; /* sensitivity per X, Y, Z axis */
 	int nfo; /* null field output */
 } mmc35240_props_table[] = {
 	/* 16 bits, 125Hz ODR */
 	{
 		{1024, 1024, 1024},
 		32768,
 	},
 	/* 16 bits, 250Hz ODR */
 	{
 		{1024, 1024, 770},
 		32768,
 	},
 	/* 14 bits, 450Hz ODR */
 	{
 		{256, 256, 193},
 		8192,
 	},
 	/* 12 bits, 800Hz ODR */
 	{
 		{64, 64, 48},
 		2048,
 	},
 };

 struct mmc35240_data {
 	struct i2c_client *client;
 	struct mutex mutex;
 	struct regmap *regmap;
 	enum mmc35240_resolution res;

 	/* OTP compensation */
 	int axis_coef[3];
 	int axis_scale[3];
 };

 static const struct {
 	int val;
 	int val2;
 } mmc35240_samp_freq[] = { {1, 500000},
 			   {13, 0},
 			   {25, 0},
 			   {50, 0} };

 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");

 #define MMC35240_CHANNEL(_axis) { \
 	.type = IIO_MAGN, \
 	.modified = 1, \
 	.channel2 = IIO_MOD_ ## _axis, \
 	.address = AXIS_ ## _axis, \
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
 			BIT(IIO_CHAN_INFO_SCALE), \
 }

 static const struct iio_chan_spec mmc35240_channels[] = {
 	MMC35240_CHANNEL(X),
 	MMC35240_CHANNEL(Y),
 	MMC35240_CHANNEL(Z),
 };

 static struct attribute *mmc35240_attributes[] = {
 	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group mmc35240_attribute_group = {
 	.attrs = mmc35240_attributes,
 };

 static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
 					int val, int val2)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
 		if (mmc35240_samp_freq[i].val == val &&
 		    mmc35240_samp_freq[i].val2 == val2)
 			return i;
 	return -EINVAL;
 }

 static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
 {
 	int ret;
 	u8 coil_bit;

 	/*
 	 * Recharge the capacitor at VCAP pin, requested to be issued
 	 * before a SET/RESET command.
 	 */
 	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 				 MMC35240_CTRL0_REFILL_BIT,
 				 MMC35240_CTRL0_REFILL_BIT);
 	if (ret < 0)
 		return ret;
 	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);

 	if (set)
 		coil_bit = MMC35240_CTRL0_SET_BIT;
 	else
 		coil_bit = MMC35240_CTRL0_RESET_BIT;

 	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
 				  coil_bit, coil_bit);

 }

 static int mmc35240_init(struct mmc35240_data *data)
 {
 	int ret, y_convert, z_convert;
 	unsigned int reg_id;
 	u8 otp_data[6];

 	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
 	if (ret < 0) {
 		dev_err(&data->client->dev, "Error reading product id\n");
 		return ret;
 	}

 	dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);

 	/*
 	 * make sure we restore sensor characteristics, by doing
 	 * a SET/RESET sequence, the axis polarity being naturally
 	 * aligned after RESET
 	 */
 	ret = mmc35240_hw_set(data, true);
 	if (ret < 0)
 		return ret;
 	usleep_range(MMC35240_WAIT_SET_RESET, MMC35240_WAIT_SET_RESET + 1);

 	ret = mmc35240_hw_set(data, false);
 	if (ret < 0)
 		return ret;

 	/* set default sampling frequency */
 	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 				 MMC35240_CTRL1_BW_MASK,
 				 data->res << MMC35240_CTRL1_BW_SHIFT);
 	if (ret < 0)
 		return ret;

 	ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
 			       otp_data, sizeof(otp_data));
 	if (ret < 0)
 		return ret;

 	y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
 					   (otp_data[2] >> 4));
 	z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);

 	data->axis_coef[0] = MMC35240_X_COEFF(1);
 	data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
 	data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);

 	data->axis_scale[0] = 1;
 	data->axis_scale[1] = 1000;
 	data->axis_scale[2] = 10000;

 	return 0;
 }

 static int mmc35240_take_measurement(struct mmc35240_data *data)
 {
 	int ret, tries = 100;
 	unsigned int reg_status;

 	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
 			   MMC35240_CTRL0_TM_BIT);
 	if (ret < 0)
 		return ret;

 	while (tries-- > 0) {
 		ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
 				  &reg_status);
 		if (ret < 0)
 			return ret;
 		if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
 			break;
 		/* minimum wait time to complete measurement is 10 ms */
 		usleep_range(10000, 11000);
 	}

 	if (tries < 0) {
 		dev_err(&data->client->dev, "data not ready\n");
 		return -EIO;
 	}

 	return 0;
 }

 static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
 {
 	int ret;

 	ret = mmc35240_take_measurement(data);
 	if (ret < 0)
 		return ret;

 	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, buf,
 				3 * sizeof(__le16));
 }

 /**
  * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
  *			    compensation for output value.
  *
  * @data: device private data
  * @index: axis index for which we want the conversion
  * @buf: raw data to be converted, 2 bytes in little endian format
  * @val: compensated output reading (unit is milli gauss)
  *
  * Returns: 0 in case of success, -EINVAL when @index is not valid
  */
 static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
 				  __le16 buf[], int *val)
 {
 	int raw[3];
 	int sens[3];
 	int nfo;

 	raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
 	raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
 	raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);

 	sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
 	sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
 	sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];

 	nfo = mmc35240_props_table[data->res].nfo;

 	switch (index) {
 	case AXIS_X:
 		*val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
 		break;
 	case AXIS_Y:
 		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
 			(raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
 		break;
 	case AXIS_Z:
 		*val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
 			(raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
 		break;
 	default:
 		return -EINVAL;
 	}
 	/* apply OTP compensation */
 	*val = (*val) * data->axis_coef[index] / data->axis_scale[index];

 	return 0;
 }

 static int mmc35240_read_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan, int *val,
 			     int *val2, long mask)
 {
 	struct mmc35240_data *data = iio_priv(indio_dev);
 	int ret, i;
 	unsigned int reg;
 	__le16 buf[3];

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&data->mutex);
 		ret = mmc35240_read_measurement(data, buf);
 		mutex_unlock(&data->mutex);
 		if (ret < 0)
 			return ret;
 		ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
 		if (ret < 0)
 			return ret;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = 0;
 		*val2 = 1000;
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		mutex_lock(&data->mutex);
 		ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
 		mutex_unlock(&data->mutex);
 		if (ret < 0)
 			return ret;

 		i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
 		if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
 			return -EINVAL;

 		*val = mmc35240_samp_freq[i].val;
 		*val2 = mmc35240_samp_freq[i].val2;
 		return IIO_VAL_INT_PLUS_MICRO;
 	default:
 		return -EINVAL;
 	}
 }

 static int mmc35240_write_raw(struct iio_dev *indio_dev,
 			      struct iio_chan_spec const *chan, int val,
 			      int val2, long mask)
 {
 	struct mmc35240_data *data = iio_priv(indio_dev);
 	int i, ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		i = mmc35240_get_samp_freq_index(data, val, val2);
 		if (i < 0)
 			return -EINVAL;
 		mutex_lock(&data->mutex);
 		ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
 					 MMC35240_CTRL1_BW_MASK,
 					 i << MMC35240_CTRL1_BW_SHIFT);
 		mutex_unlock(&data->mutex);
 		return ret;
 	default:
 		return -EINVAL;
 	}
 }

 static const struct iio_info mmc35240_info = {
 	.read_raw	= mmc35240_read_raw,
 	.write_raw	= mmc35240_write_raw,
 	.attrs		= &mmc35240_attribute_group,
 };

 static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MMC35240_REG_CTRL0:
 	case MMC35240_REG_CTRL1:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MMC35240_REG_XOUT_L:
 	case MMC35240_REG_XOUT_H:
 	case MMC35240_REG_YOUT_L:
 	case MMC35240_REG_YOUT_H:
 	case MMC35240_REG_ZOUT_L:
 	case MMC35240_REG_ZOUT_H:
 	case MMC35240_REG_STATUS:
 	case MMC35240_REG_ID:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MMC35240_REG_CTRL0:
 	case MMC35240_REG_CTRL1:
 		return false;
 	default:
 		return true;
 	}
 }

 static const struct reg_default mmc35240_reg_defaults[] = {
 	{ MMC35240_REG_CTRL0,  0x00 },
 	{ MMC35240_REG_CTRL1,  0x00 },
 };

 static const struct regmap_config mmc35240_regmap_config = {
 	.name = MMC35240_REGMAP_NAME,

 	.reg_bits = 8,
 	.val_bits = 8,

 	.max_register = MMC35240_REG_ID,
 	.cache_type = REGCACHE_FLAT,

 	.writeable_reg = mmc35240_is_writeable_reg,
 	.readable_reg = mmc35240_is_readable_reg,
 	.volatile_reg = mmc35240_is_volatile_reg,

 	.reg_defaults = mmc35240_reg_defaults,
 	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
 };

 static int mmc35240_probe(struct i2c_client *client)
 {
 	struct mmc35240_data *data;
 	struct iio_dev *indio_dev;
 	struct regmap *regmap;
 	int ret;

 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;

 	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
 	if (IS_ERR(regmap)) {
 		dev_err(&client->dev, "regmap initialization failed\n");
 		return PTR_ERR(regmap);
 	}

 	data = iio_priv(indio_dev);
 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;
 	data->regmap = regmap;
 	data->res = MMC35240_16_BITS_SLOW;

 	mutex_init(&data->mutex);

 	indio_dev->info = &mmc35240_info;
 	indio_dev->name = MMC35240_DRV_NAME;
 	indio_dev->channels = mmc35240_channels;
 	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	ret = mmc35240_init(data);
 	if (ret < 0) {
 		dev_err(&client->dev, "mmc35240 chip init failed\n");
 		return ret;
 	}
 	return devm_iio_device_register(&client->dev, indio_dev);
 }

 static int mmc35240_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 	struct mmc35240_data *data = iio_priv(indio_dev);

 	regcache_cache_only(data->regmap, true);

 	return 0;
 }

 static int mmc35240_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
 	struct mmc35240_data *data = iio_priv(indio_dev);
 	int ret;

 	regcache_mark_dirty(data->regmap);
 	ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
 				   MMC35240_REG_CTRL1);
 	if (ret < 0)
 		dev_err(dev, "Failed to restore control registers\n");

 	regcache_cache_only(data->regmap, false);

 	return 0;
 }

 static DEFINE_SIMPLE_DEV_PM_OPS(mmc35240_pm_ops, mmc35240_suspend,
 				mmc35240_resume);

 static const struct of_device_id mmc35240_of_match[] = {
 	{ .compatible = "memsic,mmc35240", },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, mmc35240_of_match);

 static const struct acpi_device_id mmc35240_acpi_match[] = {
 	{"MMC35240", 0},
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);

 static const struct i2c_device_id mmc35240_id[] = {
 	{"mmc35240", 0},
 	{}
 };
 MODULE_DEVICE_TABLE(i2c, mmc35240_id);

 static struct i2c_driver mmc35240_driver = {
 	.driver = {
 		.name = MMC35240_DRV_NAME,
 		.of_match_table = mmc35240_of_match,
 		.pm = pm_sleep_ptr(&mmc35240_pm_ops),
 		.acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
 	},
 	.probe_new	= mmc35240_probe,
 	.id_table	= mmc35240_id,
 };

 module_i2c_driver(mmc35240_driver);

 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* MMC35240 - MEMSIC 3-axis Magnetic Sensor
	*
	* Copyright (c) 2015, Intel Corporation.
	*
	* IIO driver for MMC35240 (7-bit I2C slave address 0x30).
	*
	* TODO: offset, ACPI, continuous measurement mode, PM
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/i2c.h>
	#include <linux/delay.h>
	#include <linux/regmap.h>
	#include <linux/acpi.h>
	#include <linux/pm.h>

	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>

	#define MMC35240_DRV_NAME "mmc35240"
	#define MMC35240_REGMAP_NAME "mmc35240_regmap"

	#define MMC35240_REG_XOUT_L 0x00
	#define MMC35240_REG_XOUT_H 0x01
	#define MMC35240_REG_YOUT_L 0x02
	#define MMC35240_REG_YOUT_H 0x03
	#define MMC35240_REG_ZOUT_L 0x04
	#define MMC35240_REG_ZOUT_H 0x05

	#define MMC35240_REG_STATUS 0x06
	#define MMC35240_REG_CTRL0 0x07
	#define MMC35240_REG_CTRL1 0x08

	#define MMC35240_REG_ID 0x20

	#define MMC35240_STATUS_MEAS_DONE_BIT BIT(0)

	#define MMC35240_CTRL0_REFILL_BIT BIT(7)
	#define MMC35240_CTRL0_RESET_BIT BIT(6)
	#define MMC35240_CTRL0_SET_BIT BIT(5)
	#define MMC35240_CTRL0_CMM_BIT BIT(1)
	#define MMC35240_CTRL0_TM_BIT BIT(0)

	/* output resolution bits */
	#define MMC35240_CTRL1_BW0_BIT BIT(0)
	#define MMC35240_CTRL1_BW1_BIT BIT(1)

	#define MMC35240_CTRL1_BW_MASK (MMC35240_CTRL1_BW0_BIT \| \
	MMC35240_CTRL1_BW1_BIT)
	#define MMC35240_CTRL1_BW_SHIFT 0

	#define MMC35240_WAIT_CHARGE_PUMP 50000 /* us */
	#define MMC35240_WAIT_SET_RESET 1000 /* us */

	/*
	* Memsic OTP process code piece is put here for reference:
	*
	* #define OTP_CONVERT(REG) ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
	* 1) For X axis, the COEFFICIENT is always 1.
	* 2) For Y axis, the COEFFICIENT is as below:
	* f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) \|
	* (reg_data[2] >> 4)) + 1.0;
	* 3) For Z axis, the COEFFICIENT is as below:
	* f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
	* We implemented the OTP logic into driver.
	*/

	/* scale = 1000 here for Y otp */
	#define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)

	/* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
	#define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)

	#define MMC35240_X_COEFF(x) (x)
	#define MMC35240_Y_COEFF(y) (y + 1000)
	#define MMC35240_Z_COEFF(z) (z + 13500)

	#define MMC35240_OTP_START_ADDR 0x1B

	enum mmc35240_resolution {
	MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
	MMC35240_16_BITS_FAST, /* 4.08 ms */
	MMC35240_14_BITS, /* 2.16 ms */
	MMC35240_12_BITS, /* 1.20 ms */
	};

	enum mmc35240_axis {
	AXIS_X = 0,
	AXIS_Y,
	AXIS_Z,
	};

	static const struct {
	int sens[3]; /* sensitivity per X, Y, Z axis */
	int nfo; /* null field output */
	} mmc35240_props_table[] = {
	/* 16 bits, 125Hz ODR */
	{
	{1024, 1024, 1024},
	32768,
	},
	/* 16 bits, 250Hz ODR */
	{
	{1024, 1024, 770},
	32768,
	},
	/* 14 bits, 450Hz ODR */
	{
	{256, 256, 193},
	8192,
	},
	/* 12 bits, 800Hz ODR */
	{
	{64, 64, 48},
	2048,
	},
	};

	struct mmc35240_data {
	struct i2c_client *client;
	struct mutex mutex;
	struct regmap *regmap;
	enum mmc35240_resolution res;

	/* OTP compensation */
	int axis_coef[3];
	int axis_scale[3];
	};

	static const struct {
	int val;
	int val2;
	} mmc35240_samp_freq[] = { {1, 500000},
	{13, 0},
	{25, 0},
	{50, 0} };

	static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");

	#define MMC35240_CHANNEL(_axis) { \
	.type = IIO_MAGN, \
	.modified = 1, \
	.channel2 = IIO_MOD_ ## _axis, \
	.address = AXIS_ ## _axis, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) \| \
	BIT(IIO_CHAN_INFO_SCALE), \
	}

	static const struct iio_chan_spec mmc35240_channels[] = {
	MMC35240_CHANNEL(X),
	MMC35240_CHANNEL(Y),
	MMC35240_CHANNEL(Z),
	};

	static struct attribute *mmc35240_attributes[] = {
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
	NULL
	};

	static const struct attribute_group mmc35240_attribute_group = {
	.attrs = mmc35240_attributes,
	};

	static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
	int val, int val2)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
	if (mmc35240_samp_freq[i].val == val &&
	mmc35240_samp_freq[i].val2 == val2)
	return i;
	return -EINVAL;
	}

	static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
	{
	int ret;
	u8 coil_bit;

	/*
	* Recharge the capacitor at VCAP pin, requested to be issued
	* before a SET/RESET command.
	*/
	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
	MMC35240_CTRL0_REFILL_BIT,
	MMC35240_CTRL0_REFILL_BIT);
	if (ret < 0)
	return ret;
	usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);

	if (set)
	coil_bit = MMC35240_CTRL0_SET_BIT;
	else
	coil_bit = MMC35240_CTRL0_RESET_BIT;

	return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
	coil_bit, coil_bit);

	}

	static int mmc35240_init(struct mmc35240_data *data)
	{
	int ret, y_convert, z_convert;
	unsigned int reg_id;
	u8 otp_data[6];

	ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
	if (ret < 0) {
	dev_err(&data->client->dev, "Error reading product id\n");
	return ret;
	}

	dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);

	/*
	* make sure we restore sensor characteristics, by doing
	* a SET/RESET sequence, the axis polarity being naturally
	* aligned after RESET
	*/
	ret = mmc35240_hw_set(data, true);
	if (ret < 0)
	return ret;
	usleep_range(MMC35240_WAIT_SET_RESET, MMC35240_WAIT_SET_RESET + 1);

	ret = mmc35240_hw_set(data, false);
	if (ret < 0)
	return ret;

	/* set default sampling frequency */
	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
	MMC35240_CTRL1_BW_MASK,
	data->res << MMC35240_CTRL1_BW_SHIFT);
	if (ret < 0)
	return ret;

	ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
	otp_data, sizeof(otp_data));
	if (ret < 0)
	return ret;

	y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) \|
	(otp_data[2] >> 4));
	z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);

	data->axis_coef[0] = MMC35240_X_COEFF(1);
	data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
	data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);

	data->axis_scale[0] = 1;
	data->axis_scale[1] = 1000;
	data->axis_scale[2] = 10000;

	return 0;
	}

	static int mmc35240_take_measurement(struct mmc35240_data *data)
	{
	int ret, tries = 100;
	unsigned int reg_status;

	ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
	MMC35240_CTRL0_TM_BIT);
	if (ret < 0)
	return ret;

	while (tries-- > 0) {
	ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
	&reg_status);
	if (ret < 0)
	return ret;
	if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
	break;
	/* minimum wait time to complete measurement is 10 ms */
	usleep_range(10000, 11000);
	}

	if (tries < 0) {
	dev_err(&data->client->dev, "data not ready\n");
	return -EIO;
	}

	return 0;
	}

	static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
	{
	int ret;

	ret = mmc35240_take_measurement(data);
	if (ret < 0)
	return ret;

	return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, buf,
	3 * sizeof(__le16));
	}

	/**
	* mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
	* compensation for output value.
	*
	* @data: device private data
	* @index: axis index for which we want the conversion
	* @buf: raw data to be converted, 2 bytes in little endian format
	* @val: compensated output reading (unit is milli gauss)
	*
	* Returns: 0 in case of success, -EINVAL when @index is not valid
	*/
	static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
	__le16 buf[], int *val)
	{
	int raw[3];
	int sens[3];
	int nfo;

	raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
	raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
	raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);

	sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
	sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
	sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];

	nfo = mmc35240_props_table[data->res].nfo;

	switch (index) {
	case AXIS_X:
	val = (raw[AXIS_X] - nfo) 1000 / sens[AXIS_X];
	break;
	case AXIS_Y:
	val = (raw[AXIS_Y] - nfo) 1000 / sens[AXIS_Y] -
	(raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
	break;
	case AXIS_Z:
	val = (raw[AXIS_Y] - nfo) 1000 / sens[AXIS_Y] +
	(raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
	break;
	default:
	return -EINVAL;
	}
	/* apply OTP compensation */
	val = (val) * data->axis_coef[index] / data->axis_scale[index];

	return 0;
	}

	static int mmc35240_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const chan, int val,
	int *val2, long mask)
	{
	struct mmc35240_data *data = iio_priv(indio_dev);
	int ret, i;
	unsigned int reg;
	__le16 buf[3];

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	mutex_lock(&data->mutex);
	ret = mmc35240_read_measurement(data, buf);
	mutex_unlock(&data->mutex);
	if (ret < 0)
	return ret;
	ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
	if (ret < 0)
	return ret;
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	*val = 0;
	*val2 = 1000;
	return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
	mutex_lock(&data->mutex);
	ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
	mutex_unlock(&data->mutex);
	if (ret < 0)
	return ret;

	i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
	if (i < 0 \|\| i >= ARRAY_SIZE(mmc35240_samp_freq))
	return -EINVAL;

	*val = mmc35240_samp_freq[i].val;
	*val2 = mmc35240_samp_freq[i].val2;
	return IIO_VAL_INT_PLUS_MICRO;
	default:
	return -EINVAL;
	}
	}

	static int mmc35240_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan, int val,
	int val2, long mask)
	{
	struct mmc35240_data *data = iio_priv(indio_dev);
	int i, ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	i = mmc35240_get_samp_freq_index(data, val, val2);
	if (i < 0)
	return -EINVAL;
	mutex_lock(&data->mutex);
	ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
	MMC35240_CTRL1_BW_MASK,
	i << MMC35240_CTRL1_BW_SHIFT);
	mutex_unlock(&data->mutex);
	return ret;
	default:
	return -EINVAL;
	}
	}

	static const struct iio_info mmc35240_info = {
	.read_raw = mmc35240_read_raw,
	.write_raw = mmc35240_write_raw,
	.attrs = &mmc35240_attribute_group,
	};

	static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MMC35240_REG_CTRL0:
	case MMC35240_REG_CTRL1:
	return true;
	default:
	return false;
	}
	}

	static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MMC35240_REG_XOUT_L:
	case MMC35240_REG_XOUT_H:
	case MMC35240_REG_YOUT_L:
	case MMC35240_REG_YOUT_H:
	case MMC35240_REG_ZOUT_L:
	case MMC35240_REG_ZOUT_H:
	case MMC35240_REG_STATUS:
	case MMC35240_REG_ID:
	return true;
	default:
	return false;
	}
	}

	static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MMC35240_REG_CTRL0:
	case MMC35240_REG_CTRL1:
	return false;
	default:
	return true;
	}
	}

	static const struct reg_default mmc35240_reg_defaults[] = {
	{ MMC35240_REG_CTRL0, 0x00 },
	{ MMC35240_REG_CTRL1, 0x00 },
	};

	static const struct regmap_config mmc35240_regmap_config = {
	.name = MMC35240_REGMAP_NAME,

	.reg_bits = 8,
	.val_bits = 8,

	.max_register = MMC35240_REG_ID,
	.cache_type = REGCACHE_FLAT,

	.writeable_reg = mmc35240_is_writeable_reg,
	.readable_reg = mmc35240_is_readable_reg,
	.volatile_reg = mmc35240_is_volatile_reg,

	.reg_defaults = mmc35240_reg_defaults,
	.num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
	};

	static int mmc35240_probe(struct i2c_client *client)
	{
	struct mmc35240_data *data;
	struct iio_dev *indio_dev;
	struct regmap *regmap;
	int ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
	return -ENOMEM;

	regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
	if (IS_ERR(regmap)) {
	dev_err(&client->dev, "regmap initialization failed\n");
	return PTR_ERR(regmap);
	}

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	data->client = client;
	data->regmap = regmap;
	data->res = MMC35240_16_BITS_SLOW;

	mutex_init(&data->mutex);

	indio_dev->info = &mmc35240_info;
	indio_dev->name = MMC35240_DRV_NAME;
	indio_dev->channels = mmc35240_channels;
	indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = mmc35240_init(data);
	if (ret < 0) {
	dev_err(&client->dev, "mmc35240 chip init failed\n");
	return ret;
	}
	return devm_iio_device_register(&client->dev, indio_dev);
	}

	static int mmc35240_suspend(struct device *dev)
	{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	struct mmc35240_data *data = iio_priv(indio_dev);

	regcache_cache_only(data->regmap, true);

	return 0;
	}

	static int mmc35240_resume(struct device *dev)
	{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	struct mmc35240_data *data = iio_priv(indio_dev);
	int ret;

	regcache_mark_dirty(data->regmap);
	ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
	MMC35240_REG_CTRL1);
	if (ret < 0)
	dev_err(dev, "Failed to restore control registers\n");

	regcache_cache_only(data->regmap, false);

	return 0;
	}

	static DEFINE_SIMPLE_DEV_PM_OPS(mmc35240_pm_ops, mmc35240_suspend,
	mmc35240_resume);

	static const struct of_device_id mmc35240_of_match[] = {
	{ .compatible = "memsic,mmc35240", },
	{ }
	};
	MODULE_DEVICE_TABLE(of, mmc35240_of_match);

	static const struct acpi_device_id mmc35240_acpi_match[] = {
	{"MMC35240", 0},
	{ },
	};
	MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);

	static const struct i2c_device_id mmc35240_id[] = {
	{"mmc35240", 0},
	{}
	};
	MODULE_DEVICE_TABLE(i2c, mmc35240_id);

	static struct i2c_driver mmc35240_driver = {
	.driver = {
	.name = MMC35240_DRV_NAME,
	.of_match_table = mmc35240_of_match,
	.pm = pm_sleep_ptr(&mmc35240_pm_ops),
	.acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
	},
	.probe_new = mmc35240_probe,
	.id_table = mmc35240_id,
	};

	module_i2c_driver(mmc35240_driver);

	MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
	MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
	MODULE_LICENSE("GPL v2");