drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c - pub/scm/linux/kernel/git/minchan/linux - Git at Google

 /*
  * STMicroelectronics st_lsm6dsx FIFO buffer library driver
  *
  * LSM6DS3/LSM6DSM: The FIFO buffer can be configured to store data
  * from gyroscope and accelerometer. Samples are queued without any tag
  * according to a specific pattern based on 'FIFO data sets' (6 bytes each):
  *  - 1st data set is reserved for gyroscope data
  *  - 2nd data set is reserved for accelerometer data
  * The FIFO pattern changes depending on the ODRs and decimation factors
  * assigned to the FIFO data sets. The first sequence of data stored in FIFO
  * buffer contains the data of all the enabled FIFO data sets
  * (e.g. Gx, Gy, Gz, Ax, Ay, Az), then data are repeated depending on the
  * value of the decimation factor and ODR set for each FIFO data set.
  * FIFO supported modes:
  *  - BYPASS: FIFO disabled
  *  - CONTINUOUS: FIFO enabled. When the buffer is full, the FIFO index
  *    restarts from the beginning and the oldest sample is overwritten
  *
  * Copyright 2016 STMicroelectronics Inc.
  *
  * Lorenzo Bianconi <lorenzo.bianconi@st.com>
  * Denis Ciocca <denis.ciocca@st.com>
  *
  * Licensed under the GPL-2.
  */
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/iio/kfifo_buf.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/buffer.h>

 #include "st_lsm6dsx.h"

 #define ST_LSM6DSX_REG_FIFO_THL_ADDR		0x06
 #define ST_LSM6DSX_REG_FIFO_THH_ADDR		0x07
 #define ST_LSM6DSX_FIFO_TH_MASK			GENMASK(11, 0)
 #define ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR	0x08
 #define ST_LSM6DSX_REG_FIFO_MODE_ADDR		0x0a
 #define ST_LSM6DSX_FIFO_MODE_MASK		GENMASK(2, 0)
 #define ST_LSM6DSX_FIFO_ODR_MASK		GENMASK(6, 3)
 #define ST_LSM6DSX_REG_FIFO_DIFFL_ADDR		0x3a
 #define ST_LSM6DSX_FIFO_DIFF_MASK		GENMASK(11, 0)
 #define ST_LSM6DSX_FIFO_EMPTY_MASK		BIT(12)
 #define ST_LSM6DSX_REG_FIFO_OUTL_ADDR		0x3e

 #define ST_LSM6DSX_MAX_FIFO_ODR_VAL		0x08

 struct st_lsm6dsx_decimator_entry {
 	u8 decimator;
 	u8 val;
 };

 static const
 struct st_lsm6dsx_decimator_entry st_lsm6dsx_decimator_table[] = {
 	{  0, 0x0 },
 	{  1, 0x1 },
 	{  2, 0x2 },
 	{  3, 0x3 },
 	{  4, 0x4 },
 	{  8, 0x5 },
 	{ 16, 0x6 },
 	{ 32, 0x7 },
 };

 static int st_lsm6dsx_get_decimator_val(u8 val)
 {
 	const int max_size = ARRAY_SIZE(st_lsm6dsx_decimator_table);
 	int i;

 	for (i = 0; i < max_size; i++)
 		if (st_lsm6dsx_decimator_table[i].decimator == val)
 			break;

 	return i == max_size ? 0 : st_lsm6dsx_decimator_table[i].val;
 }

 static void st_lsm6dsx_get_max_min_odr(struct st_lsm6dsx_hw *hw,
 				       u16 *max_odr, u16 *min_odr)
 {
 	struct st_lsm6dsx_sensor *sensor;
 	int i;

 	*max_odr = 0, *min_odr = ~0;
 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
 		sensor = iio_priv(hw->iio_devs[i]);

 		if (!(hw->enable_mask & BIT(sensor->id)))
 			continue;

 		*max_odr = max_t(u16, *max_odr, sensor->odr);
 		*min_odr = min_t(u16, *min_odr, sensor->odr);
 	}
 }

 static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
 {
 	struct st_lsm6dsx_sensor *sensor;
 	u16 max_odr, min_odr, sip = 0;
 	int err, i;
 	u8 data;

 	st_lsm6dsx_get_max_min_odr(hw, &max_odr, &min_odr);

 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
 		sensor = iio_priv(hw->iio_devs[i]);

 		/* update fifo decimators and sample in pattern */
 		if (hw->enable_mask & BIT(sensor->id)) {
 			sensor->sip = sensor->odr / min_odr;
 			sensor->decimator = max_odr / sensor->odr;
 			data = st_lsm6dsx_get_decimator_val(sensor->decimator);
 		} else {
 			sensor->sip = 0;
 			sensor->decimator = 0;
 			data = 0;
 		}

 		err = st_lsm6dsx_write_with_mask(hw,
 					ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR,
 					sensor->decimator_mask, data);
 		if (err < 0)
 			return err;

 		sip += sensor->sip;
 	}
 	hw->sip = sip;

 	return 0;
 }

 static int st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw *hw,
 				    enum st_lsm6dsx_fifo_mode fifo_mode)
 {
 	u8 data;
 	int err;

 	switch (fifo_mode) {
 	case ST_LSM6DSX_FIFO_BYPASS:
 		data = fifo_mode;
 		break;
 	case ST_LSM6DSX_FIFO_CONT:
 		data = (ST_LSM6DSX_MAX_FIFO_ODR_VAL <<
 			__ffs(ST_LSM6DSX_FIFO_ODR_MASK)) | fifo_mode;
 		break;
 	default:
 		return -EINVAL;
 	}

 	err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
 			    sizeof(data), &data);
 	if (err < 0)
 		return err;

 	hw->fifo_mode = fifo_mode;

 	return 0;
 }

 int st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor *sensor, u16 watermark)
 {
 	u16 fifo_watermark = ~0, cur_watermark, sip = 0;
 	struct st_lsm6dsx_hw *hw = sensor->hw;
 	struct st_lsm6dsx_sensor *cur_sensor;
 	__le16 wdata;
 	int i, err;
 	u8 data;

 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
 		cur_sensor = iio_priv(hw->iio_devs[i]);

 		if (!(hw->enable_mask & BIT(cur_sensor->id)))
 			continue;

 		cur_watermark = (cur_sensor == sensor) ? watermark
 						       : cur_sensor->watermark;

 		fifo_watermark = min_t(u16, fifo_watermark, cur_watermark);
 		sip += cur_sensor->sip;
 	}

 	if (!sip)
 		return 0;

 	fifo_watermark = max_t(u16, fifo_watermark, sip);
 	fifo_watermark = (fifo_watermark / sip) * sip;
 	fifo_watermark = fifo_watermark * ST_LSM6DSX_SAMPLE_DEPTH;

 	mutex_lock(&hw->lock);

 	err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_THH_ADDR,
 			   sizeof(data), &data);
 	if (err < 0)
 		goto out;

 	fifo_watermark = ((data << 8) & ~ST_LSM6DSX_FIFO_TH_MASK) |
 			 (fifo_watermark & ST_LSM6DSX_FIFO_TH_MASK);

 	wdata = cpu_to_le16(fifo_watermark);
 	err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_FIFO_THL_ADDR,
 			    sizeof(wdata), (u8 *)&wdata);
 out:
 	mutex_unlock(&hw->lock);

 	return err < 0 ? err : 0;
 }

 /**
  * st_lsm6dsx_read_fifo() - LSM6DS3-LSM6DSM read FIFO routine
  * @hw: Pointer to instance of struct st_lsm6dsx_hw.
  *
  * Read samples from the hw FIFO and push them to IIO buffers.
  *
  * Return: Number of bytes read from the FIFO
  */
 static int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
 {
 	u16 fifo_len, pattern_len = hw->sip * ST_LSM6DSX_SAMPLE_SIZE;
 	int err, acc_sip, gyro_sip, read_len, samples, offset;
 	struct st_lsm6dsx_sensor *acc_sensor, *gyro_sensor;
 	s64 acc_ts, acc_delta_ts, gyro_ts, gyro_delta_ts;
 	u8 iio_buff[ALIGN(ST_LSM6DSX_SAMPLE_SIZE, sizeof(s64)) + sizeof(s64)];
 	u8 buff[pattern_len];
 	__le16 fifo_status;

 	err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_DIFFL_ADDR,
 			   sizeof(fifo_status), (u8 *)&fifo_status);
 	if (err < 0)
 		return err;

 	if (fifo_status & cpu_to_le16(ST_LSM6DSX_FIFO_EMPTY_MASK))
 		return 0;

 	fifo_len = (le16_to_cpu(fifo_status) & ST_LSM6DSX_FIFO_DIFF_MASK) *
 		   ST_LSM6DSX_CHAN_SIZE;
 	samples = fifo_len / ST_LSM6DSX_SAMPLE_SIZE;
 	fifo_len = (fifo_len / pattern_len) * pattern_len;

 	/*
 	 * compute delta timestamp between two consecutive samples
 	 * in order to estimate queueing time of data generated
 	 * by the sensor
 	 */
 	acc_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
 	acc_ts = acc_sensor->ts - acc_sensor->delta_ts;
 	acc_delta_ts = div_s64(acc_sensor->delta_ts * acc_sensor->decimator,
 			       samples);

 	gyro_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_GYRO]);
 	gyro_ts = gyro_sensor->ts - gyro_sensor->delta_ts;
 	gyro_delta_ts = div_s64(gyro_sensor->delta_ts * gyro_sensor->decimator,
 				samples);

 	for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
 		err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_OUTL_ADDR,
 				   sizeof(buff), buff);
 		if (err < 0)
 			return err;

 		/*
 		 * Data are written to the FIFO with a specific pattern
 		 * depending on the configured ODRs. The first sequence of data
 		 * stored in FIFO contains the data of all enabled sensors
 		 * (e.g. Gx, Gy, Gz, Ax, Ay, Az), then data are repeated
 		 * depending on the value of the decimation factor set for each
 		 * sensor.
 		 *
 		 * Supposing the FIFO is storing data from gyroscope and
 		 * accelerometer at different ODRs:
 		 *   - gyroscope ODR = 208Hz, accelerometer ODR = 104Hz
 		 * Since the gyroscope ODR is twice the accelerometer one, the
 		 * following pattern is repeated every 9 samples:
 		 *   - Gx, Gy, Gz, Ax, Ay, Az, Gx, Gy, Gz
 		 */
 		gyro_sip = gyro_sensor->sip;
 		acc_sip = acc_sensor->sip;
 		offset = 0;

 		while (acc_sip > 0 || gyro_sip > 0) {
 			if (gyro_sip-- > 0) {
 				memcpy(iio_buff, &buff[offset],
 				       ST_LSM6DSX_SAMPLE_SIZE);
 				iio_push_to_buffers_with_timestamp(
 					hw->iio_devs[ST_LSM6DSX_ID_GYRO],
 					iio_buff, gyro_ts);
 				offset += ST_LSM6DSX_SAMPLE_SIZE;
 				gyro_ts += gyro_delta_ts;
 			}

 			if (acc_sip-- > 0) {
 				memcpy(iio_buff, &buff[offset],
 				       ST_LSM6DSX_SAMPLE_SIZE);
 				iio_push_to_buffers_with_timestamp(
 					hw->iio_devs[ST_LSM6DSX_ID_ACC],
 					iio_buff, acc_ts);
 				offset += ST_LSM6DSX_SAMPLE_SIZE;
 				acc_ts += acc_delta_ts;
 			}
 		}
 	}

 	return read_len;
 }

 static int st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw *hw)
 {
 	int err;

 	mutex_lock(&hw->fifo_lock);

 	st_lsm6dsx_read_fifo(hw);
 	err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_BYPASS);

 	mutex_unlock(&hw->fifo_lock);

 	return err;
 }

 static int st_lsm6dsx_update_fifo(struct iio_dev *iio_dev, bool enable)
 {
 	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
 	struct st_lsm6dsx_hw *hw = sensor->hw;
 	int err;

 	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS) {
 		err = st_lsm6dsx_flush_fifo(hw);
 		if (err < 0)
 			return err;
 	}

 	if (enable) {
 		err = st_lsm6dsx_sensor_enable(sensor);
 		if (err < 0)
 			return err;
 	} else {
 		err = st_lsm6dsx_sensor_disable(sensor);
 		if (err < 0)
 			return err;
 	}

 	err = st_lsm6dsx_update_decimators(hw);
 	if (err < 0)
 		return err;

 	err = st_lsm6dsx_update_watermark(sensor, sensor->watermark);
 	if (err < 0)
 		return err;

 	if (hw->enable_mask) {
 		err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
 		if (err < 0)
 			return err;

 		/*
 		 * store enable buffer timestamp as reference to compute
 		 * first delta timestamp
 		 */
 		sensor->ts = iio_get_time_ns(iio_dev);
 	}

 	return 0;
 }

 static irqreturn_t st_lsm6dsx_handler_irq(int irq, void *private)
 {
 	struct st_lsm6dsx_hw *hw = (struct st_lsm6dsx_hw *)private;
 	struct st_lsm6dsx_sensor *sensor;
 	int i;

 	if (!hw->sip)
 		return IRQ_NONE;

 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
 		sensor = iio_priv(hw->iio_devs[i]);

 		if (sensor->sip > 0) {
 			s64 timestamp;

 			timestamp = iio_get_time_ns(hw->iio_devs[i]);
 			sensor->delta_ts = timestamp - sensor->ts;
 			sensor->ts = timestamp;
 		}
 	}

 	return IRQ_WAKE_THREAD;
 }

 static irqreturn_t st_lsm6dsx_handler_thread(int irq, void *private)
 {
 	struct st_lsm6dsx_hw *hw = (struct st_lsm6dsx_hw *)private;
 	int count;

 	mutex_lock(&hw->fifo_lock);
 	count = st_lsm6dsx_read_fifo(hw);
 	mutex_unlock(&hw->fifo_lock);

 	return !count ? IRQ_NONE : IRQ_HANDLED;
 }

 static int st_lsm6dsx_buffer_preenable(struct iio_dev *iio_dev)
 {
 	return st_lsm6dsx_update_fifo(iio_dev, true);
 }

 static int st_lsm6dsx_buffer_postdisable(struct iio_dev *iio_dev)
 {
 	return st_lsm6dsx_update_fifo(iio_dev, false);
 }

 static const struct iio_buffer_setup_ops st_lsm6dsx_buffer_ops = {
 	.preenable = st_lsm6dsx_buffer_preenable,
 	.postdisable = st_lsm6dsx_buffer_postdisable,
 };

 int st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw *hw)
 {
 	struct iio_buffer *buffer;
 	unsigned long irq_type;
 	int i, err;

 	irq_type = irqd_get_trigger_type(irq_get_irq_data(hw->irq));

 	switch (irq_type) {
 	case IRQF_TRIGGER_HIGH:
 	case IRQF_TRIGGER_RISING:
 		break;
 	default:
 		dev_info(hw->dev, "mode %lx unsupported\n", irq_type);
 		return -EINVAL;
 	}

 	err = devm_request_threaded_irq(hw->dev, hw->irq,
 					st_lsm6dsx_handler_irq,
 					st_lsm6dsx_handler_thread,
 					irq_type | IRQF_ONESHOT,
 					"lsm6dsx", hw);
 	if (err) {
 		dev_err(hw->dev, "failed to request trigger irq %d\n",
 			hw->irq);
 		return err;
 	}

 	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
 		buffer = devm_iio_kfifo_allocate(hw->dev);
 		if (!buffer)
 			return -ENOMEM;

 		iio_device_attach_buffer(hw->iio_devs[i], buffer);
 		hw->iio_devs[i]->modes |= INDIO_BUFFER_SOFTWARE;
 		hw->iio_devs[i]->setup_ops = &st_lsm6dsx_buffer_ops;
 	}

 	return 0;
 }
	/*
	* STMicroelectronics st_lsm6dsx FIFO buffer library driver
	*
	* LSM6DS3/LSM6DSM: The FIFO buffer can be configured to store data
	* from gyroscope and accelerometer. Samples are queued without any tag
	* according to a specific pattern based on 'FIFO data sets' (6 bytes each):
	* - 1st data set is reserved for gyroscope data
	* - 2nd data set is reserved for accelerometer data
	* The FIFO pattern changes depending on the ODRs and decimation factors
	* assigned to the FIFO data sets. The first sequence of data stored in FIFO
	* buffer contains the data of all the enabled FIFO data sets
	* (e.g. Gx, Gy, Gz, Ax, Ay, Az), then data are repeated depending on the
	* value of the decimation factor and ODR set for each FIFO data set.
	* FIFO supported modes:
	* - BYPASS: FIFO disabled
	* - CONTINUOUS: FIFO enabled. When the buffer is full, the FIFO index
	* restarts from the beginning and the oldest sample is overwritten
	*
	* Copyright 2016 STMicroelectronics Inc.
	*
	* Lorenzo Bianconi <lorenzo.bianconi@st.com>
	* Denis Ciocca <denis.ciocca@st.com>
	*
	* Licensed under the GPL-2.
	*/
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/iio/kfifo_buf.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/buffer.h>

	#include "st_lsm6dsx.h"

	#define ST_LSM6DSX_REG_FIFO_THL_ADDR 0x06
	#define ST_LSM6DSX_REG_FIFO_THH_ADDR 0x07
	#define ST_LSM6DSX_FIFO_TH_MASK GENMASK(11, 0)
	#define ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR 0x08
	#define ST_LSM6DSX_REG_FIFO_MODE_ADDR 0x0a
	#define ST_LSM6DSX_FIFO_MODE_MASK GENMASK(2, 0)
	#define ST_LSM6DSX_FIFO_ODR_MASK GENMASK(6, 3)
	#define ST_LSM6DSX_REG_FIFO_DIFFL_ADDR 0x3a
	#define ST_LSM6DSX_FIFO_DIFF_MASK GENMASK(11, 0)
	#define ST_LSM6DSX_FIFO_EMPTY_MASK BIT(12)
	#define ST_LSM6DSX_REG_FIFO_OUTL_ADDR 0x3e

	#define ST_LSM6DSX_MAX_FIFO_ODR_VAL 0x08

	struct st_lsm6dsx_decimator_entry {
	u8 decimator;
	u8 val;
	};

	static const
	struct st_lsm6dsx_decimator_entry st_lsm6dsx_decimator_table[] = {
	{ 0, 0x0 },
	{ 1, 0x1 },
	{ 2, 0x2 },
	{ 3, 0x3 },
	{ 4, 0x4 },
	{ 8, 0x5 },
	{ 16, 0x6 },
	{ 32, 0x7 },
	};

	static int st_lsm6dsx_get_decimator_val(u8 val)
	{
	const int max_size = ARRAY_SIZE(st_lsm6dsx_decimator_table);
	int i;

	for (i = 0; i < max_size; i++)
	if (st_lsm6dsx_decimator_table[i].decimator == val)
	break;

	return i == max_size ? 0 : st_lsm6dsx_decimator_table[i].val;
	}

	static void st_lsm6dsx_get_max_min_odr(struct st_lsm6dsx_hw *hw,
	u16 max_odr, u16 min_odr)
	{
	struct st_lsm6dsx_sensor *sensor;
	int i;

	max_odr = 0, min_odr = ~0;
	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
	sensor = iio_priv(hw->iio_devs[i]);

	if (!(hw->enable_mask & BIT(sensor->id)))
	continue;

	max_odr = max_t(u16, max_odr, sensor->odr);
	min_odr = min_t(u16, min_odr, sensor->odr);
	}
	}

	static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
	{
	struct st_lsm6dsx_sensor *sensor;
	u16 max_odr, min_odr, sip = 0;
	int err, i;
	u8 data;

	st_lsm6dsx_get_max_min_odr(hw, &max_odr, &min_odr);

	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
	sensor = iio_priv(hw->iio_devs[i]);

	/* update fifo decimators and sample in pattern */
	if (hw->enable_mask & BIT(sensor->id)) {
	sensor->sip = sensor->odr / min_odr;
	sensor->decimator = max_odr / sensor->odr;
	data = st_lsm6dsx_get_decimator_val(sensor->decimator);
	} else {
	sensor->sip = 0;
	sensor->decimator = 0;
	data = 0;
	}

	err = st_lsm6dsx_write_with_mask(hw,
	ST_LSM6DSX_REG_FIFO_DEC_GXL_ADDR,
	sensor->decimator_mask, data);
	if (err < 0)
	return err;

	sip += sensor->sip;
	}
	hw->sip = sip;

	return 0;
	}

	static int st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw *hw,
	enum st_lsm6dsx_fifo_mode fifo_mode)
	{
	u8 data;
	int err;

	switch (fifo_mode) {
	case ST_LSM6DSX_FIFO_BYPASS:
	data = fifo_mode;
	break;
	case ST_LSM6DSX_FIFO_CONT:
	data = (ST_LSM6DSX_MAX_FIFO_ODR_VAL <<
	__ffs(ST_LSM6DSX_FIFO_ODR_MASK)) \| fifo_mode;
	break;
	default:
	return -EINVAL;
	}

	err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
	sizeof(data), &data);
	if (err < 0)
	return err;

	hw->fifo_mode = fifo_mode;

	return 0;
	}

	int st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor *sensor, u16 watermark)
	{
	u16 fifo_watermark = ~0, cur_watermark, sip = 0;
	struct st_lsm6dsx_hw *hw = sensor->hw;
	struct st_lsm6dsx_sensor *cur_sensor;
	__le16 wdata;
	int i, err;
	u8 data;

	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
	cur_sensor = iio_priv(hw->iio_devs[i]);

	if (!(hw->enable_mask & BIT(cur_sensor->id)))
	continue;

	cur_watermark = (cur_sensor == sensor) ? watermark
	: cur_sensor->watermark;

	fifo_watermark = min_t(u16, fifo_watermark, cur_watermark);
	sip += cur_sensor->sip;
	}

	if (!sip)
	return 0;

	fifo_watermark = max_t(u16, fifo_watermark, sip);
	fifo_watermark = (fifo_watermark / sip) * sip;
	fifo_watermark = fifo_watermark * ST_LSM6DSX_SAMPLE_DEPTH;

	mutex_lock(&hw->lock);

	err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_THH_ADDR,
	sizeof(data), &data);
	if (err < 0)
	goto out;

	fifo_watermark = ((data << 8) & ~ST_LSM6DSX_FIFO_TH_MASK) \|
	(fifo_watermark & ST_LSM6DSX_FIFO_TH_MASK);

	wdata = cpu_to_le16(fifo_watermark);
	err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_FIFO_THL_ADDR,
	sizeof(wdata), (u8 *)&wdata);
	out:
	mutex_unlock(&hw->lock);

	return err < 0 ? err : 0;
	}

	/**
	* st_lsm6dsx_read_fifo() - LSM6DS3-LSM6DSM read FIFO routine
	* @hw: Pointer to instance of struct st_lsm6dsx_hw.
	*
	* Read samples from the hw FIFO and push them to IIO buffers.
	*
	* Return: Number of bytes read from the FIFO
	*/
	static int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
	{
	u16 fifo_len, pattern_len = hw->sip * ST_LSM6DSX_SAMPLE_SIZE;
	int err, acc_sip, gyro_sip, read_len, samples, offset;
	struct st_lsm6dsx_sensor acc_sensor, gyro_sensor;
	s64 acc_ts, acc_delta_ts, gyro_ts, gyro_delta_ts;
	u8 iio_buff[ALIGN(ST_LSM6DSX_SAMPLE_SIZE, sizeof(s64)) + sizeof(s64)];
	u8 buff[pattern_len];
	__le16 fifo_status;

	err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_DIFFL_ADDR,
	sizeof(fifo_status), (u8 *)&fifo_status);
	if (err < 0)
	return err;

	if (fifo_status & cpu_to_le16(ST_LSM6DSX_FIFO_EMPTY_MASK))
	return 0;

	fifo_len = (le16_to_cpu(fifo_status) & ST_LSM6DSX_FIFO_DIFF_MASK) *
	ST_LSM6DSX_CHAN_SIZE;
	samples = fifo_len / ST_LSM6DSX_SAMPLE_SIZE;
	fifo_len = (fifo_len / pattern_len) * pattern_len;

	/*
	* compute delta timestamp between two consecutive samples
	* in order to estimate queueing time of data generated
	* by the sensor
	*/
	acc_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
	acc_ts = acc_sensor->ts - acc_sensor->delta_ts;
	acc_delta_ts = div_s64(acc_sensor->delta_ts * acc_sensor->decimator,
	samples);

	gyro_sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_GYRO]);
	gyro_ts = gyro_sensor->ts - gyro_sensor->delta_ts;
	gyro_delta_ts = div_s64(gyro_sensor->delta_ts * gyro_sensor->decimator,
	samples);

	for (read_len = 0; read_len < fifo_len; read_len += pattern_len) {
	err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_FIFO_OUTL_ADDR,
	sizeof(buff), buff);
	if (err < 0)
	return err;

	/*
	* Data are written to the FIFO with a specific pattern
	* depending on the configured ODRs. The first sequence of data
	* stored in FIFO contains the data of all enabled sensors
	* (e.g. Gx, Gy, Gz, Ax, Ay, Az), then data are repeated
	* depending on the value of the decimation factor set for each
	* sensor.
	*
	* Supposing the FIFO is storing data from gyroscope and
	* accelerometer at different ODRs:
	* - gyroscope ODR = 208Hz, accelerometer ODR = 104Hz
	* Since the gyroscope ODR is twice the accelerometer one, the
	* following pattern is repeated every 9 samples:
	* - Gx, Gy, Gz, Ax, Ay, Az, Gx, Gy, Gz
	*/
	gyro_sip = gyro_sensor->sip;
	acc_sip = acc_sensor->sip;
	offset = 0;

	while (acc_sip > 0 \|\| gyro_sip > 0) {
	if (gyro_sip-- > 0) {
	memcpy(iio_buff, &buff[offset],
	ST_LSM6DSX_SAMPLE_SIZE);
	iio_push_to_buffers_with_timestamp(
	hw->iio_devs[ST_LSM6DSX_ID_GYRO],
	iio_buff, gyro_ts);
	offset += ST_LSM6DSX_SAMPLE_SIZE;
	gyro_ts += gyro_delta_ts;
	}

	if (acc_sip-- > 0) {
	memcpy(iio_buff, &buff[offset],
	ST_LSM6DSX_SAMPLE_SIZE);
	iio_push_to_buffers_with_timestamp(
	hw->iio_devs[ST_LSM6DSX_ID_ACC],
	iio_buff, acc_ts);
	offset += ST_LSM6DSX_SAMPLE_SIZE;
	acc_ts += acc_delta_ts;
	}
	}
	}

	return read_len;
	}

	static int st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw *hw)
	{
	int err;

	mutex_lock(&hw->fifo_lock);

	st_lsm6dsx_read_fifo(hw);
	err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_BYPASS);

	mutex_unlock(&hw->fifo_lock);

	return err;
	}

	static int st_lsm6dsx_update_fifo(struct iio_dev *iio_dev, bool enable)
	{
	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
	struct st_lsm6dsx_hw *hw = sensor->hw;
	int err;

	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS) {
	err = st_lsm6dsx_flush_fifo(hw);
	if (err < 0)
	return err;
	}

	if (enable) {
	err = st_lsm6dsx_sensor_enable(sensor);
	if (err < 0)
	return err;
	} else {
	err = st_lsm6dsx_sensor_disable(sensor);
	if (err < 0)
	return err;
	}

	err = st_lsm6dsx_update_decimators(hw);
	if (err < 0)
	return err;

	err = st_lsm6dsx_update_watermark(sensor, sensor->watermark);
	if (err < 0)
	return err;

	if (hw->enable_mask) {
	err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
	if (err < 0)
	return err;

	/*
	* store enable buffer timestamp as reference to compute
	* first delta timestamp
	*/
	sensor->ts = iio_get_time_ns(iio_dev);
	}

	return 0;
	}

	static irqreturn_t st_lsm6dsx_handler_irq(int irq, void *private)
	{
	struct st_lsm6dsx_hw hw = (struct st_lsm6dsx_hw )private;
	struct st_lsm6dsx_sensor *sensor;
	int i;

	if (!hw->sip)
	return IRQ_NONE;

	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
	sensor = iio_priv(hw->iio_devs[i]);

	if (sensor->sip > 0) {
	s64 timestamp;

	timestamp = iio_get_time_ns(hw->iio_devs[i]);
	sensor->delta_ts = timestamp - sensor->ts;
	sensor->ts = timestamp;
	}
	}

	return IRQ_WAKE_THREAD;
	}

	static irqreturn_t st_lsm6dsx_handler_thread(int irq, void *private)
	{
	struct st_lsm6dsx_hw hw = (struct st_lsm6dsx_hw )private;
	int count;

	mutex_lock(&hw->fifo_lock);
	count = st_lsm6dsx_read_fifo(hw);
	mutex_unlock(&hw->fifo_lock);

	return !count ? IRQ_NONE : IRQ_HANDLED;
	}

	static int st_lsm6dsx_buffer_preenable(struct iio_dev *iio_dev)
	{
	return st_lsm6dsx_update_fifo(iio_dev, true);
	}

	static int st_lsm6dsx_buffer_postdisable(struct iio_dev *iio_dev)
	{
	return st_lsm6dsx_update_fifo(iio_dev, false);
	}

	static const struct iio_buffer_setup_ops st_lsm6dsx_buffer_ops = {
	.preenable = st_lsm6dsx_buffer_preenable,
	.postdisable = st_lsm6dsx_buffer_postdisable,
	};

	int st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw *hw)
	{
	struct iio_buffer *buffer;
	unsigned long irq_type;
	int i, err;

	irq_type = irqd_get_trigger_type(irq_get_irq_data(hw->irq));

	switch (irq_type) {
	case IRQF_TRIGGER_HIGH:
	case IRQF_TRIGGER_RISING:
	break;
	default:
	dev_info(hw->dev, "mode %lx unsupported\n", irq_type);
	return -EINVAL;
	}

	err = devm_request_threaded_irq(hw->dev, hw->irq,
	st_lsm6dsx_handler_irq,
	st_lsm6dsx_handler_thread,
	irq_type \| IRQF_ONESHOT,
	"lsm6dsx", hw);
	if (err) {
	dev_err(hw->dev, "failed to request trigger irq %d\n",
	hw->irq);
	return err;
	}

	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
	buffer = devm_iio_kfifo_allocate(hw->dev);
	if (!buffer)
	return -ENOMEM;

	iio_device_attach_buffer(hw->iio_devs[i], buffer);
	hw->iio_devs[i]->modes \|= INDIO_BUFFER_SOFTWARE;
	hw->iio_devs[i]->setup_ops = &st_lsm6dsx_buffer_ops;
	}

	return 0;
	}