drivers/iio/accel/bmi088-accel-core.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * 3-axis accelerometer driver supporting following Bosch-Sensortec chips:
  *  - BMI088
  *
  * Copyright (c) 2018-2021, Topic Embedded Products
  */

 #include <linux/delay.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <asm/unaligned.h>

 #include "bmi088-accel.h"

 #define BMI088_ACCEL_REG_CHIP_ID			0x00
 #define BMI088_ACCEL_REG_ERROR				0x02

 #define BMI088_ACCEL_REG_INT_STATUS			0x1D
 #define BMI088_ACCEL_INT_STATUS_BIT_DRDY		BIT(7)

 #define BMI088_ACCEL_REG_RESET				0x7E
 #define BMI088_ACCEL_RESET_VAL				0xB6

 #define BMI088_ACCEL_REG_PWR_CTRL			0x7D
 #define BMI088_ACCEL_REG_PWR_CONF			0x7C

 #define BMI088_ACCEL_REG_INT_MAP_DATA			0x58
 #define BMI088_ACCEL_INT_MAP_DATA_BIT_INT1_DRDY		BIT(2)
 #define BMI088_ACCEL_INT_MAP_DATA_BIT_INT2_FWM		BIT(5)

 #define BMI088_ACCEL_REG_INT1_IO_CONF			0x53
 #define BMI088_ACCEL_INT1_IO_CONF_BIT_ENABLE_OUT	BIT(3)
 #define BMI088_ACCEL_INT1_IO_CONF_BIT_LVL		BIT(1)

 #define BMI088_ACCEL_REG_INT2_IO_CONF			0x54
 #define BMI088_ACCEL_INT2_IO_CONF_BIT_ENABLE_OUT	BIT(3)
 #define BMI088_ACCEL_INT2_IO_CONF_BIT_LVL		BIT(1)

 #define BMI088_ACCEL_REG_ACC_CONF			0x40
 #define BMI088_ACCEL_MODE_ODR_MASK			0x0f

 #define BMI088_ACCEL_REG_ACC_RANGE			0x41
 #define BMI088_ACCEL_RANGE_3G				0x00
 #define BMI088_ACCEL_RANGE_6G				0x01
 #define BMI088_ACCEL_RANGE_12G				0x02
 #define BMI088_ACCEL_RANGE_24G				0x03

 #define BMI088_ACCEL_REG_TEMP				0x22
 #define BMI088_ACCEL_REG_TEMP_SHIFT			5
 #define BMI088_ACCEL_TEMP_UNIT				125
 #define BMI088_ACCEL_TEMP_OFFSET			23000

 #define BMI088_ACCEL_REG_XOUT_L				0x12
 #define BMI088_ACCEL_AXIS_TO_REG(axis) \
 	(BMI088_ACCEL_REG_XOUT_L + (axis * 2))

 #define BMI088_ACCEL_MAX_STARTUP_TIME_US		1000
 #define BMI088_AUTO_SUSPEND_DELAY_MS			2000

 #define BMI088_ACCEL_REG_FIFO_STATUS			0x0E
 #define BMI088_ACCEL_REG_FIFO_CONFIG0			0x48
 #define BMI088_ACCEL_REG_FIFO_CONFIG1			0x49
 #define BMI088_ACCEL_REG_FIFO_DATA			0x3F
 #define BMI088_ACCEL_FIFO_LENGTH			100

 #define BMI088_ACCEL_FIFO_MODE_FIFO			0x40
 #define BMI088_ACCEL_FIFO_MODE_STREAM			0x80

 enum bmi088_accel_axis {
 	AXIS_X,
 	AXIS_Y,
 	AXIS_Z,
 };

 static const int bmi088_sample_freqs[] = {
 	12, 500000,
 	25, 0,
 	50, 0,
 	100, 0,
 	200, 0,
 	400, 0,
 	800, 0,
 	1600, 0,
 };

 /* Available OSR (over sampling rate) sets the 3dB cut-off frequency */
 enum bmi088_osr_modes {
 	BMI088_ACCEL_MODE_OSR_NORMAL = 0xA,
 	BMI088_ACCEL_MODE_OSR_2 = 0x9,
 	BMI088_ACCEL_MODE_OSR_4 = 0x8,
 };

 /* Available ODR (output data rates) in Hz */
 enum bmi088_odr_modes {
 	BMI088_ACCEL_MODE_ODR_12_5 = 0x5,
 	BMI088_ACCEL_MODE_ODR_25 = 0x6,
 	BMI088_ACCEL_MODE_ODR_50 = 0x7,
 	BMI088_ACCEL_MODE_ODR_100 = 0x8,
 	BMI088_ACCEL_MODE_ODR_200 = 0x9,
 	BMI088_ACCEL_MODE_ODR_400 = 0xa,
 	BMI088_ACCEL_MODE_ODR_800 = 0xb,
 	BMI088_ACCEL_MODE_ODR_1600 = 0xc,
 };

 struct bmi088_scale_info {
 	int scale;
 	u8 reg_range;
 };

 struct bmi088_accel_chip_info {
 	const char *name;
 	u8 chip_id;
 	const struct iio_chan_spec *channels;
 	int num_channels;
 };

 struct bmi088_accel_data {
 	struct regmap *regmap;
 	const struct bmi088_accel_chip_info *chip_info;
 	u8 buffer[2] ____cacheline_aligned; /* shared DMA safe buffer */
 };

 static const struct regmap_range bmi088_volatile_ranges[] = {
 	/* All registers below 0x40 are volatile, except the CHIP ID. */
 	regmap_reg_range(BMI088_ACCEL_REG_ERROR, 0x3f),
 	/* Mark the RESET as volatile too, it is self-clearing */
 	regmap_reg_range(BMI088_ACCEL_REG_RESET, BMI088_ACCEL_REG_RESET),
 };

 static const struct regmap_access_table bmi088_volatile_table = {
 	.yes_ranges	= bmi088_volatile_ranges,
 	.n_yes_ranges	= ARRAY_SIZE(bmi088_volatile_ranges),
 };

 const struct regmap_config bmi088_regmap_conf = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = 0x7E,
 	.volatile_table = &bmi088_volatile_table,
 	.cache_type = REGCACHE_RBTREE,
 };
 EXPORT_SYMBOL_GPL(bmi088_regmap_conf);

 static int bmi088_accel_power_up(struct bmi088_accel_data *data)
 {
 	int ret;

 	/* Enable accelerometer and temperature sensor */
 	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CTRL, 0x4);
 	if (ret)
 		return ret;

 	/* Datasheet recommends to wait at least 5ms before communication */
 	usleep_range(5000, 6000);

 	/* Disable suspend mode */
 	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CONF, 0x0);
 	if (ret)
 		return ret;

 	/* Recommended at least 1ms before further communication */
 	usleep_range(1000, 1200);

 	return 0;
 }

 static int bmi088_accel_power_down(struct bmi088_accel_data *data)
 {
 	int ret;

 	/* Enable suspend mode */
 	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CONF, 0x3);
 	if (ret)
 		return ret;

 	/* Recommended at least 1ms before further communication */
 	usleep_range(1000, 1200);

 	/* Disable accelerometer and temperature sensor */
 	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CTRL, 0x0);
 	if (ret)
 		return ret;

 	/* Datasheet recommends to wait at least 5ms before communication */
 	usleep_range(5000, 6000);

 	return 0;
 }

 static int bmi088_accel_get_sample_freq(struct bmi088_accel_data *data,
 					int *val, int *val2)
 {
 	unsigned int value;
 	int ret;

 	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_ACC_CONF,
 			  &value);
 	if (ret)
 		return ret;

 	value &= BMI088_ACCEL_MODE_ODR_MASK;
 	value -= BMI088_ACCEL_MODE_ODR_12_5;
 	value <<= 1;

 	if (value >= ARRAY_SIZE(bmi088_sample_freqs) - 1)
 		return -EINVAL;

 	*val = bmi088_sample_freqs[value];
 	*val2 = bmi088_sample_freqs[value + 1];

 	return IIO_VAL_INT_PLUS_MICRO;
 }

 static int bmi088_accel_set_sample_freq(struct bmi088_accel_data *data, int val)
 {
 	unsigned int regval;
 	int index = 0;

 	while (index < ARRAY_SIZE(bmi088_sample_freqs) &&
 	       bmi088_sample_freqs[index] != val)
 		index += 2;

 	if (index >= ARRAY_SIZE(bmi088_sample_freqs))
 		return -EINVAL;

 	regval = (index >> 1) + BMI088_ACCEL_MODE_ODR_12_5;

 	return regmap_update_bits(data->regmap, BMI088_ACCEL_REG_ACC_CONF,
 				  BMI088_ACCEL_MODE_ODR_MASK, regval);
 }

 static int bmi088_accel_get_temp(struct bmi088_accel_data *data, int *val)
 {
 	int ret;
 	s16 temp;

 	ret = regmap_bulk_read(data->regmap, BMI088_ACCEL_REG_TEMP,
 			       &data->buffer, sizeof(__be16));
 	if (ret)
 		return ret;

 	/* data->buffer is cacheline aligned */
 	temp = be16_to_cpu(*(__be16 *)data->buffer);

 	*val = temp >> BMI088_ACCEL_REG_TEMP_SHIFT;

 	return IIO_VAL_INT;
 }

 static int bmi088_accel_get_axis(struct bmi088_accel_data *data,
 				 struct iio_chan_spec const *chan,
 				 int *val)
 {
 	int ret;
 	s16 raw_val;

 	ret = regmap_bulk_read(data->regmap,
 			       BMI088_ACCEL_AXIS_TO_REG(chan->scan_index),
 			       data->buffer, sizeof(__le16));
 	if (ret)
 		return ret;

 	raw_val = le16_to_cpu(*(__le16 *)data->buffer);
 	*val = raw_val;

 	return IIO_VAL_INT;
 }

 static int bmi088_accel_read_raw(struct iio_dev *indio_dev,
 				 struct iio_chan_spec const *chan,
 				 int *val, int *val2, long mask)
 {
 	struct bmi088_accel_data *data = iio_priv(indio_dev);
 	struct device *dev = regmap_get_device(data->regmap);
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		switch (chan->type) {
 		case IIO_TEMP:
 			ret = pm_runtime_resume_and_get(dev);
 			if (ret)
 				return ret;

 			ret = bmi088_accel_get_temp(data, val);
 			goto out_read_raw_pm_put;
 		case IIO_ACCEL:
 			ret = pm_runtime_resume_and_get(dev);
 			if (ret)
 				return ret;

 			ret = iio_device_claim_direct_mode(indio_dev);
 			if (ret)
 				goto out_read_raw_pm_put;

 			ret = bmi088_accel_get_axis(data, chan, val);
 			iio_device_release_direct_mode(indio_dev);
 			if (!ret)
 				ret = IIO_VAL_INT;

 			goto out_read_raw_pm_put;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_OFFSET:
 		switch (chan->type) {
 		case IIO_TEMP:
 			/* Offset applies before scale */
 			*val = BMI088_ACCEL_TEMP_OFFSET/BMI088_ACCEL_TEMP_UNIT;
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_TEMP:
 			/* 0.125 degrees per LSB */
 			*val = BMI088_ACCEL_TEMP_UNIT;
 			return IIO_VAL_INT;
 		case IIO_ACCEL:
 			ret = pm_runtime_resume_and_get(dev);
 			if (ret)
 				return ret;

 			ret = regmap_read(data->regmap,
 					  BMI088_ACCEL_REG_ACC_RANGE, val);
 			if (ret)
 				goto out_read_raw_pm_put;

 			*val2 = 15 - (*val & 0x3);
 			*val = 3 * 980;
 			ret = IIO_VAL_FRACTIONAL_LOG2;

 			goto out_read_raw_pm_put;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		ret = pm_runtime_resume_and_get(dev);
 		if (ret)
 			return ret;

 		ret = bmi088_accel_get_sample_freq(data, val, val2);
 		goto out_read_raw_pm_put;
 	default:
 		break;
 	}

 	return -EINVAL;

 out_read_raw_pm_put:
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_put_autosuspend(dev);

 	return ret;
 }

 static int bmi088_accel_read_avail(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     const int **vals, int *type, int *length,
 			     long mask)
 {
 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*type = IIO_VAL_INT_PLUS_MICRO;
 		*vals = bmi088_sample_freqs;
 		*length = ARRAY_SIZE(bmi088_sample_freqs);
 		return IIO_AVAIL_LIST;
 	default:
 		return -EINVAL;
 	}
 }

 static int bmi088_accel_write_raw(struct iio_dev *indio_dev,
 				  struct iio_chan_spec const *chan,
 				  int val, int val2, long mask)
 {
 	struct bmi088_accel_data *data = iio_priv(indio_dev);
 	struct device *dev = regmap_get_device(data->regmap);
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		ret = pm_runtime_resume_and_get(dev);
 		if (ret)
 			return ret;

 		ret = bmi088_accel_set_sample_freq(data, val);
 		pm_runtime_mark_last_busy(dev);
 		pm_runtime_put_autosuspend(dev);
 		return ret;
 	default:
 		return -EINVAL;
 	}
 }

 #define BMI088_ACCEL_CHANNEL(_axis) { \
 	.type = IIO_ACCEL, \
 	.modified = 1, \
 	.channel2 = IIO_MOD_##_axis, \
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
 				BIT(IIO_CHAN_INFO_SAMP_FREQ), \
 	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
 	.scan_index = AXIS_##_axis, \
 }

 static const struct iio_chan_spec bmi088_accel_channels[] = {
 	{
 		.type = IIO_TEMP,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE) |
 				      BIT(IIO_CHAN_INFO_OFFSET),
 		.scan_index = -1,
 	},
 	BMI088_ACCEL_CHANNEL(X),
 	BMI088_ACCEL_CHANNEL(Y),
 	BMI088_ACCEL_CHANNEL(Z),
 	IIO_CHAN_SOFT_TIMESTAMP(3),
 };

 static const struct bmi088_accel_chip_info bmi088_accel_chip_info_tbl[] = {
 	[0] = {
 		.name = "bmi088a",
 		.chip_id = 0x1E,
 		.channels = bmi088_accel_channels,
 		.num_channels = ARRAY_SIZE(bmi088_accel_channels),
 	},
 };

 static const struct iio_info bmi088_accel_info = {
 	.read_raw	= bmi088_accel_read_raw,
 	.write_raw	= bmi088_accel_write_raw,
 	.read_avail	= bmi088_accel_read_avail,
 };

 static const unsigned long bmi088_accel_scan_masks[] = {
 	BIT(AXIS_X) | BIT(AXIS_Y) | BIT(AXIS_Z),
 	0
 };

 static int bmi088_accel_chip_init(struct bmi088_accel_data *data)
 {
 	struct device *dev = regmap_get_device(data->regmap);
 	int ret, i;
 	unsigned int val;

 	/* Do a dummy read to enable SPI interface, won't harm I2C */
 	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);

 	/*
 	 * Reset chip to get it in a known good state. A delay of 1ms after
 	 * reset is required according to the data sheet
 	 */
 	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_RESET,
 			   BMI088_ACCEL_RESET_VAL);
 	if (ret)
 		return ret;

 	usleep_range(1000, 2000);

 	/* Do a dummy read again after a reset to enable the SPI interface */
 	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);

 	/* Read chip ID */
 	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_CHIP_ID, &val);
 	if (ret) {
 		dev_err(dev, "Error: Reading chip id\n");
 		return ret;
 	}

 	/* Validate chip ID */
 	for (i = 0; i < ARRAY_SIZE(bmi088_accel_chip_info_tbl); i++) {
 		if (bmi088_accel_chip_info_tbl[i].chip_id == val) {
 			data->chip_info = &bmi088_accel_chip_info_tbl[i];
 			break;
 		}
 	}
 	if (i == ARRAY_SIZE(bmi088_accel_chip_info_tbl)) {
 		dev_err(dev, "Invalid chip %x\n", val);
 		return -ENODEV;
 	}

 	return 0;
 }

 int bmi088_accel_core_probe(struct device *dev, struct regmap *regmap,
 	int irq, const char *name, bool block_supported)
 {
 	struct bmi088_accel_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);
 	dev_set_drvdata(dev, indio_dev);

 	data->regmap = regmap;

 	ret = bmi088_accel_chip_init(data);
 	if (ret)
 		return ret;

 	indio_dev->channels = data->chip_info->channels;
 	indio_dev->num_channels = data->chip_info->num_channels;
 	indio_dev->name = name ? name : data->chip_info->name;
 	indio_dev->available_scan_masks = bmi088_accel_scan_masks;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &bmi088_accel_info;

 	/* Enable runtime PM */
 	pm_runtime_get_noresume(dev);
 	pm_runtime_set_suspended(dev);
 	pm_runtime_enable(dev);
 	/* We need ~6ms to startup, so set the delay to 6 seconds */
 	pm_runtime_set_autosuspend_delay(dev, 6000);
 	pm_runtime_use_autosuspend(dev);
 	pm_runtime_put(dev);

 	ret = iio_device_register(indio_dev);
 	if (ret)
 		dev_err(dev, "Unable to register iio device\n");

 	return ret;
 }
 EXPORT_SYMBOL_GPL(bmi088_accel_core_probe);


 void bmi088_accel_core_remove(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct bmi088_accel_data *data = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);

 	pm_runtime_disable(dev);
 	pm_runtime_set_suspended(dev);
 	bmi088_accel_power_down(data);
 }
 EXPORT_SYMBOL_GPL(bmi088_accel_core_remove);

 static int __maybe_unused bmi088_accel_runtime_suspend(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct bmi088_accel_data *data = iio_priv(indio_dev);

 	return bmi088_accel_power_down(data);
 }

 static int __maybe_unused bmi088_accel_runtime_resume(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct bmi088_accel_data *data = iio_priv(indio_dev);

 	return bmi088_accel_power_up(data);
 }

 const struct dev_pm_ops bmi088_accel_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
 				pm_runtime_force_resume)
 	SET_RUNTIME_PM_OPS(bmi088_accel_runtime_suspend,
 			   bmi088_accel_runtime_resume, NULL)
 };
 EXPORT_SYMBOL_GPL(bmi088_accel_pm_ops);

 MODULE_AUTHOR("Niek van Agt <niek.van.agt@topicproducts.com>");
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("BMI088 accelerometer driver (core)");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 3-axis accelerometer driver supporting following Bosch-Sensortec chips:
	* - BMI088
	*
	* Copyright (c) 2018-2021, Topic Embedded Products
	*/

	#include <linux/delay.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/pm.h>
	#include <linux/pm_runtime.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>
	#include <asm/unaligned.h>

	#include "bmi088-accel.h"

	#define BMI088_ACCEL_REG_CHIP_ID 0x00
	#define BMI088_ACCEL_REG_ERROR 0x02

	#define BMI088_ACCEL_REG_INT_STATUS 0x1D
	#define BMI088_ACCEL_INT_STATUS_BIT_DRDY BIT(7)

	#define BMI088_ACCEL_REG_RESET 0x7E
	#define BMI088_ACCEL_RESET_VAL 0xB6

	#define BMI088_ACCEL_REG_PWR_CTRL 0x7D
	#define BMI088_ACCEL_REG_PWR_CONF 0x7C

	#define BMI088_ACCEL_REG_INT_MAP_DATA 0x58
	#define BMI088_ACCEL_INT_MAP_DATA_BIT_INT1_DRDY BIT(2)
	#define BMI088_ACCEL_INT_MAP_DATA_BIT_INT2_FWM BIT(5)

	#define BMI088_ACCEL_REG_INT1_IO_CONF 0x53
	#define BMI088_ACCEL_INT1_IO_CONF_BIT_ENABLE_OUT BIT(3)
	#define BMI088_ACCEL_INT1_IO_CONF_BIT_LVL BIT(1)

	#define BMI088_ACCEL_REG_INT2_IO_CONF 0x54
	#define BMI088_ACCEL_INT2_IO_CONF_BIT_ENABLE_OUT BIT(3)
	#define BMI088_ACCEL_INT2_IO_CONF_BIT_LVL BIT(1)

	#define BMI088_ACCEL_REG_ACC_CONF 0x40
	#define BMI088_ACCEL_MODE_ODR_MASK 0x0f

	#define BMI088_ACCEL_REG_ACC_RANGE 0x41
	#define BMI088_ACCEL_RANGE_3G 0x00
	#define BMI088_ACCEL_RANGE_6G 0x01
	#define BMI088_ACCEL_RANGE_12G 0x02
	#define BMI088_ACCEL_RANGE_24G 0x03

	#define BMI088_ACCEL_REG_TEMP 0x22
	#define BMI088_ACCEL_REG_TEMP_SHIFT 5
	#define BMI088_ACCEL_TEMP_UNIT 125
	#define BMI088_ACCEL_TEMP_OFFSET 23000

	#define BMI088_ACCEL_REG_XOUT_L 0x12
	#define BMI088_ACCEL_AXIS_TO_REG(axis) \
	(BMI088_ACCEL_REG_XOUT_L + (axis * 2))

	#define BMI088_ACCEL_MAX_STARTUP_TIME_US 1000
	#define BMI088_AUTO_SUSPEND_DELAY_MS 2000

	#define BMI088_ACCEL_REG_FIFO_STATUS 0x0E
	#define BMI088_ACCEL_REG_FIFO_CONFIG0 0x48
	#define BMI088_ACCEL_REG_FIFO_CONFIG1 0x49
	#define BMI088_ACCEL_REG_FIFO_DATA 0x3F
	#define BMI088_ACCEL_FIFO_LENGTH 100

	#define BMI088_ACCEL_FIFO_MODE_FIFO 0x40
	#define BMI088_ACCEL_FIFO_MODE_STREAM 0x80

	enum bmi088_accel_axis {
	AXIS_X,
	AXIS_Y,
	AXIS_Z,
	};

	static const int bmi088_sample_freqs[] = {
	12, 500000,
	25, 0,
	50, 0,
	100, 0,
	200, 0,
	400, 0,
	800, 0,
	1600, 0,
	};

	/* Available OSR (over sampling rate) sets the 3dB cut-off frequency */
	enum bmi088_osr_modes {
	BMI088_ACCEL_MODE_OSR_NORMAL = 0xA,
	BMI088_ACCEL_MODE_OSR_2 = 0x9,
	BMI088_ACCEL_MODE_OSR_4 = 0x8,
	};

	/* Available ODR (output data rates) in Hz */
	enum bmi088_odr_modes {
	BMI088_ACCEL_MODE_ODR_12_5 = 0x5,
	BMI088_ACCEL_MODE_ODR_25 = 0x6,
	BMI088_ACCEL_MODE_ODR_50 = 0x7,
	BMI088_ACCEL_MODE_ODR_100 = 0x8,
	BMI088_ACCEL_MODE_ODR_200 = 0x9,
	BMI088_ACCEL_MODE_ODR_400 = 0xa,
	BMI088_ACCEL_MODE_ODR_800 = 0xb,
	BMI088_ACCEL_MODE_ODR_1600 = 0xc,
	};

	struct bmi088_scale_info {
	int scale;
	u8 reg_range;
	};

	struct bmi088_accel_chip_info {
	const char *name;
	u8 chip_id;
	const struct iio_chan_spec *channels;
	int num_channels;
	};

	struct bmi088_accel_data {
	struct regmap *regmap;
	const struct bmi088_accel_chip_info *chip_info;
	u8 buffer[2] ____cacheline_aligned; /* shared DMA safe buffer */
	};

	static const struct regmap_range bmi088_volatile_ranges[] = {
	/* All registers below 0x40 are volatile, except the CHIP ID. */
	regmap_reg_range(BMI088_ACCEL_REG_ERROR, 0x3f),
	/* Mark the RESET as volatile too, it is self-clearing */
	regmap_reg_range(BMI088_ACCEL_REG_RESET, BMI088_ACCEL_REG_RESET),
	};

	static const struct regmap_access_table bmi088_volatile_table = {
	.yes_ranges = bmi088_volatile_ranges,
	.n_yes_ranges = ARRAY_SIZE(bmi088_volatile_ranges),
	};

	const struct regmap_config bmi088_regmap_conf = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = 0x7E,
	.volatile_table = &bmi088_volatile_table,
	.cache_type = REGCACHE_RBTREE,
	};
	EXPORT_SYMBOL_GPL(bmi088_regmap_conf);

	static int bmi088_accel_power_up(struct bmi088_accel_data *data)
	{
	int ret;

	/* Enable accelerometer and temperature sensor */
	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CTRL, 0x4);
	if (ret)
	return ret;

	/* Datasheet recommends to wait at least 5ms before communication */
	usleep_range(5000, 6000);

	/* Disable suspend mode */
	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CONF, 0x0);
	if (ret)
	return ret;

	/* Recommended at least 1ms before further communication */
	usleep_range(1000, 1200);

	return 0;
	}

	static int bmi088_accel_power_down(struct bmi088_accel_data *data)
	{
	int ret;

	/* Enable suspend mode */
	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CONF, 0x3);
	if (ret)
	return ret;

	/* Recommended at least 1ms before further communication */
	usleep_range(1000, 1200);

	/* Disable accelerometer and temperature sensor */
	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_PWR_CTRL, 0x0);
	if (ret)
	return ret;

	/* Datasheet recommends to wait at least 5ms before communication */
	usleep_range(5000, 6000);

	return 0;
	}

	static int bmi088_accel_get_sample_freq(struct bmi088_accel_data *data,
	int val, int val2)
	{
	unsigned int value;
	int ret;

	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_ACC_CONF,
	&value);
	if (ret)
	return ret;

	value &= BMI088_ACCEL_MODE_ODR_MASK;
	value -= BMI088_ACCEL_MODE_ODR_12_5;
	value <<= 1;

	if (value >= ARRAY_SIZE(bmi088_sample_freqs) - 1)
	return -EINVAL;

	*val = bmi088_sample_freqs[value];
	*val2 = bmi088_sample_freqs[value + 1];

	return IIO_VAL_INT_PLUS_MICRO;
	}

	static int bmi088_accel_set_sample_freq(struct bmi088_accel_data *data, int val)
	{
	unsigned int regval;
	int index = 0;

	while (index < ARRAY_SIZE(bmi088_sample_freqs) &&
	bmi088_sample_freqs[index] != val)
	index += 2;

	if (index >= ARRAY_SIZE(bmi088_sample_freqs))
	return -EINVAL;

	regval = (index >> 1) + BMI088_ACCEL_MODE_ODR_12_5;

	return regmap_update_bits(data->regmap, BMI088_ACCEL_REG_ACC_CONF,
	BMI088_ACCEL_MODE_ODR_MASK, regval);
	}

	static int bmi088_accel_get_temp(struct bmi088_accel_data data, int val)
	{
	int ret;
	s16 temp;

	ret = regmap_bulk_read(data->regmap, BMI088_ACCEL_REG_TEMP,
	&data->buffer, sizeof(__be16));
	if (ret)
	return ret;

	/* data->buffer is cacheline aligned */
	temp = be16_to_cpu((__be16 )data->buffer);

	*val = temp >> BMI088_ACCEL_REG_TEMP_SHIFT;

	return IIO_VAL_INT;
	}

	static int bmi088_accel_get_axis(struct bmi088_accel_data *data,
	struct iio_chan_spec const *chan,
	int *val)
	{
	int ret;
	s16 raw_val;

	ret = regmap_bulk_read(data->regmap,
	BMI088_ACCEL_AXIS_TO_REG(chan->scan_index),
	data->buffer, sizeof(__le16));
	if (ret)
	return ret;

	raw_val = le16_to_cpu((__le16 )data->buffer);
	*val = raw_val;

	return IIO_VAL_INT;
	}

	static int bmi088_accel_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct bmi088_accel_data *data = iio_priv(indio_dev);
	struct device *dev = regmap_get_device(data->regmap);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	switch (chan->type) {
	case IIO_TEMP:
	ret = pm_runtime_resume_and_get(dev);
	if (ret)
	return ret;

	ret = bmi088_accel_get_temp(data, val);
	goto out_read_raw_pm_put;
	case IIO_ACCEL:
	ret = pm_runtime_resume_and_get(dev);
	if (ret)
	return ret;

	ret = iio_device_claim_direct_mode(indio_dev);
	if (ret)
	goto out_read_raw_pm_put;

	ret = bmi088_accel_get_axis(data, chan, val);
	iio_device_release_direct_mode(indio_dev);
	if (!ret)
	ret = IIO_VAL_INT;

	goto out_read_raw_pm_put;
	default:
	return -EINVAL;
	}
	case IIO_CHAN_INFO_OFFSET:
	switch (chan->type) {
	case IIO_TEMP:
	/* Offset applies before scale */
	*val = BMI088_ACCEL_TEMP_OFFSET/BMI088_ACCEL_TEMP_UNIT;
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	case IIO_CHAN_INFO_SCALE:
	switch (chan->type) {
	case IIO_TEMP:
	/* 0.125 degrees per LSB */
	*val = BMI088_ACCEL_TEMP_UNIT;
	return IIO_VAL_INT;
	case IIO_ACCEL:
	ret = pm_runtime_resume_and_get(dev);
	if (ret)
	return ret;

	ret = regmap_read(data->regmap,
	BMI088_ACCEL_REG_ACC_RANGE, val);
	if (ret)
	goto out_read_raw_pm_put;

	val2 = 15 - (val & 0x3);
	val = 3 980;
	ret = IIO_VAL_FRACTIONAL_LOG2;

	goto out_read_raw_pm_put;
	default:
	return -EINVAL;
	}
	case IIO_CHAN_INFO_SAMP_FREQ:
	ret = pm_runtime_resume_and_get(dev);
	if (ret)
	return ret;

	ret = bmi088_accel_get_sample_freq(data, val, val2);
	goto out_read_raw_pm_put;
	default:
	break;
	}

	return -EINVAL;

	out_read_raw_pm_put:
	pm_runtime_mark_last_busy(dev);
	pm_runtime_put_autosuspend(dev);

	return ret;
	}

	static int bmi088_accel_read_avail(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	const int *vals, int type, int *length,
	long mask)
	{
	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	*type = IIO_VAL_INT_PLUS_MICRO;
	*vals = bmi088_sample_freqs;
	*length = ARRAY_SIZE(bmi088_sample_freqs);
	return IIO_AVAIL_LIST;
	default:
	return -EINVAL;
	}
	}

	static int bmi088_accel_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct bmi088_accel_data *data = iio_priv(indio_dev);
	struct device *dev = regmap_get_device(data->regmap);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	ret = pm_runtime_resume_and_get(dev);
	if (ret)
	return ret;

	ret = bmi088_accel_set_sample_freq(data, val);
	pm_runtime_mark_last_busy(dev);
	pm_runtime_put_autosuspend(dev);
	return ret;
	default:
	return -EINVAL;
	}
	}

	#define BMI088_ACCEL_CHANNEL(_axis) { \
	.type = IIO_ACCEL, \
	.modified = 1, \
	.channel2 = IIO_MOD_##_axis, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \| \
	BIT(IIO_CHAN_INFO_SAMP_FREQ), \
	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
	.scan_index = AXIS_##_axis, \
	}

	static const struct iio_chan_spec bmi088_accel_channels[] = {
	{
	.type = IIO_TEMP,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE) \|
	BIT(IIO_CHAN_INFO_OFFSET),
	.scan_index = -1,
	},
	BMI088_ACCEL_CHANNEL(X),
	BMI088_ACCEL_CHANNEL(Y),
	BMI088_ACCEL_CHANNEL(Z),
	IIO_CHAN_SOFT_TIMESTAMP(3),
	};

	static const struct bmi088_accel_chip_info bmi088_accel_chip_info_tbl[] = {
	[0] = {
	.name = "bmi088a",
	.chip_id = 0x1E,
	.channels = bmi088_accel_channels,
	.num_channels = ARRAY_SIZE(bmi088_accel_channels),
	},
	};

	static const struct iio_info bmi088_accel_info = {
	.read_raw = bmi088_accel_read_raw,
	.write_raw = bmi088_accel_write_raw,
	.read_avail = bmi088_accel_read_avail,
	};

	static const unsigned long bmi088_accel_scan_masks[] = {
	BIT(AXIS_X) \| BIT(AXIS_Y) \| BIT(AXIS_Z),
	0
	};

	static int bmi088_accel_chip_init(struct bmi088_accel_data *data)
	{
	struct device *dev = regmap_get_device(data->regmap);
	int ret, i;
	unsigned int val;

	/* Do a dummy read to enable SPI interface, won't harm I2C */
	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);

	/*
	* Reset chip to get it in a known good state. A delay of 1ms after
	* reset is required according to the data sheet
	*/
	ret = regmap_write(data->regmap, BMI088_ACCEL_REG_RESET,
	BMI088_ACCEL_RESET_VAL);
	if (ret)
	return ret;

	usleep_range(1000, 2000);

	/* Do a dummy read again after a reset to enable the SPI interface */
	regmap_read(data->regmap, BMI088_ACCEL_REG_INT_STATUS, &val);

	/* Read chip ID */
	ret = regmap_read(data->regmap, BMI088_ACCEL_REG_CHIP_ID, &val);
	if (ret) {
	dev_err(dev, "Error: Reading chip id\n");
	return ret;
	}

	/* Validate chip ID */
	for (i = 0; i < ARRAY_SIZE(bmi088_accel_chip_info_tbl); i++) {
	if (bmi088_accel_chip_info_tbl[i].chip_id == val) {
	data->chip_info = &bmi088_accel_chip_info_tbl[i];
	break;
	}
	}
	if (i == ARRAY_SIZE(bmi088_accel_chip_info_tbl)) {
	dev_err(dev, "Invalid chip %x\n", val);
	return -ENODEV;
	}

	return 0;
	}

	int bmi088_accel_core_probe(struct device dev, struct regmap regmap,
	int irq, const char *name, bool block_supported)
	{
	struct bmi088_accel_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);
	dev_set_drvdata(dev, indio_dev);

	data->regmap = regmap;

	ret = bmi088_accel_chip_init(data);
	if (ret)
	return ret;

	indio_dev->channels = data->chip_info->channels;
	indio_dev->num_channels = data->chip_info->num_channels;
	indio_dev->name = name ? name : data->chip_info->name;
	indio_dev->available_scan_masks = bmi088_accel_scan_masks;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &bmi088_accel_info;

	/* Enable runtime PM */
	pm_runtime_get_noresume(dev);
	pm_runtime_set_suspended(dev);
	pm_runtime_enable(dev);
	/* We need ~6ms to startup, so set the delay to 6 seconds */
	pm_runtime_set_autosuspend_delay(dev, 6000);
	pm_runtime_use_autosuspend(dev);
	pm_runtime_put(dev);

	ret = iio_device_register(indio_dev);
	if (ret)
	dev_err(dev, "Unable to register iio device\n");

	return ret;
	}
	EXPORT_SYMBOL_GPL(bmi088_accel_core_probe);


	void bmi088_accel_core_remove(struct device *dev)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct bmi088_accel_data *data = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	pm_runtime_disable(dev);
	pm_runtime_set_suspended(dev);
	bmi088_accel_power_down(data);
	}
	EXPORT_SYMBOL_GPL(bmi088_accel_core_remove);

	static int __maybe_unused bmi088_accel_runtime_suspend(struct device *dev)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct bmi088_accel_data *data = iio_priv(indio_dev);

	return bmi088_accel_power_down(data);
	}

	static int __maybe_unused bmi088_accel_runtime_resume(struct device *dev)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct bmi088_accel_data *data = iio_priv(indio_dev);

	return bmi088_accel_power_up(data);
	}

	const struct dev_pm_ops bmi088_accel_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
	pm_runtime_force_resume)
	SET_RUNTIME_PM_OPS(bmi088_accel_runtime_suspend,
	bmi088_accel_runtime_resume, NULL)
	};
	EXPORT_SYMBOL_GPL(bmi088_accel_pm_ops);

	MODULE_AUTHOR("Niek van Agt <niek.van.agt@topicproducts.com>");
	MODULE_LICENSE("GPL v2");
	MODULE_DESCRIPTION("BMI088 accelerometer driver (core)");