iio: imu: add support to lsm6dsx driver

Add support to STM LSM6DS3-LSM6DSM 6-axis (acc + gyro) Mems sensor

http://www.st.com/resource/en/datasheet/lsm6ds3.pdf
http://www.st.com/resource/en/datasheet/lsm6dsm.pdf

- continuous mode support
- i2c support
- spi support
- sw fifo mode support
- supported devices: lsm6ds3, lsm6dsm
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/imu/Kconfig

@@ -39,6 +39,7 @@ config KMX61
 	  be called kmx61.
 
 source "drivers/iio/imu/inv_mpu6050/Kconfig"
+source "drivers/iio/imu/st_lsm6dsx/Kconfig"
 
 endmenu
 

drivers/iio/imu/Makefile

@@ -17,3 +17,5 @@ obj-y += bmi160/
 obj-y += inv_mpu6050/
 
 obj-$(CONFIG_KMX61) += kmx61.o
+
+obj-y += st_lsm6dsx/

drivers/iio/imu/st_lsm6dsx/Kconfig

+
+config IIO_ST_LSM6DSX
+	tristate "ST_LSM6DSx driver for STM 6-axis IMU MEMS sensors"
+	depends on (I2C || SPI)
+	select IIO_BUFFER
+	select IIO_KFIFO_BUF
+	select IIO_ST_LSM6DSX_I2C if (I2C)
+	select IIO_ST_LSM6DSX_SPI if (SPI_MASTER)
+	help
+	  Say yes here to build support for STMicroelectronics LSM6DSx imu
+	  sensor. Supported devices: lsm6ds3, lsm6dsm
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called st_lsm6dsx.
+
+config IIO_ST_LSM6DSX_I2C
+	tristate
+	depends on IIO_ST_LSM6DSX
+
+config IIO_ST_LSM6DSX_SPI
+	tristate
+	depends on IIO_ST_LSM6DSX

drivers/iio/imu/st_lsm6dsx/Makefile

+st_lsm6dsx-y := st_lsm6dsx_core.o st_lsm6dsx_buffer.o
+
+obj-$(CONFIG_IIO_ST_LSM6DSX) += st_lsm6dsx.o
+obj-$(CONFIG_IIO_ST_LSM6DSX_I2C) += st_lsm6dsx_i2c.o
+obj-$(CONFIG_IIO_ST_LSM6DSX_SPI) += st_lsm6dsx_spi.o

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h

+/*
+ * STMicroelectronics st_lsm6dsx sensor driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi@st.com>
+ * Denis Ciocca <denis.ciocca@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#ifndef ST_LSM6DSX_H
+#define ST_LSM6DSX_H
+
+#include <linux/device.h>
+
+#define ST_LSM6DS3_DEV_NAME	"lsm6ds3"
+#define ST_LSM6DSM_DEV_NAME	"lsm6dsm"
+
+enum st_lsm6dsx_hw_id {
+	ST_LSM6DS3_ID,
+	ST_LSM6DSM_ID,
+};
+
+#define ST_LSM6DSX_CHAN_SIZE		2
+#define ST_LSM6DSX_SAMPLE_SIZE		6
+#define ST_LSM6DSX_SAMPLE_DEPTH		(ST_LSM6DSX_SAMPLE_SIZE / \
+					 ST_LSM6DSX_CHAN_SIZE)
+
+#if defined(CONFIG_SPI_MASTER)
+#define ST_LSM6DSX_RX_MAX_LENGTH	256
+#define ST_LSM6DSX_TX_MAX_LENGTH	8
+
+struct st_lsm6dsx_transfer_buffer {
+	u8 rx_buf[ST_LSM6DSX_RX_MAX_LENGTH];
+	u8 tx_buf[ST_LSM6DSX_TX_MAX_LENGTH] ____cacheline_aligned;
+};
+#endif /* CONFIG_SPI_MASTER */
+
+struct st_lsm6dsx_transfer_function {
+	int (*read)(struct device *dev, u8 addr, int len, u8 *data);
+	int (*write)(struct device *dev, u8 addr, int len, u8 *data);
+};
+
+struct st_lsm6dsx_reg {
+	u8 addr;
+	u8 mask;
+};
+
+struct st_lsm6dsx_settings {
+	u8 wai;
+	u16 max_fifo_size;
+	enum st_lsm6dsx_hw_id id;
+};
+
+enum st_lsm6dsx_sensor_id {
+	ST_LSM6DSX_ID_ACC,
+	ST_LSM6DSX_ID_GYRO,
+	ST_LSM6DSX_ID_MAX,
+};
+
+enum st_lsm6dsx_fifo_mode {
+	ST_LSM6DSX_FIFO_BYPASS = 0x0,
+	ST_LSM6DSX_FIFO_CONT = 0x6,
+};
+
+/**
+ * struct st_lsm6dsx_sensor - ST IMU sensor instance
+ * @id: Sensor identifier.
+ * @hw: Pointer to instance of struct st_lsm6dsx_hw.
+ * @gain: Configured sensor sensitivity.
+ * @odr: Output data rate of the sensor [Hz].
+ * @watermark: Sensor watermark level.
+ * @sip: Number of samples in a given pattern.
+ * @decimator: FIFO decimation factor.
+ * @decimator_mask: Sensor mask for decimation register.
+ * @delta_ts: Delta time between two consecutive interrupts.
+ * @ts: Latest timestamp from the interrupt handler.
+ */
+struct st_lsm6dsx_sensor {
+	enum st_lsm6dsx_sensor_id id;
+	struct st_lsm6dsx_hw *hw;
+
+	u32 gain;
+	u16 odr;
+
+	u16 watermark;
+	u8 sip;
+	u8 decimator;
+	u8 decimator_mask;
+
+	s64 delta_ts;
+	s64 ts;
+};
+
+/**
+ * struct st_lsm6dsx_hw - ST IMU MEMS hw instance
+ * @dev: Pointer to instance of struct device (I2C or SPI).
+ * @irq: Device interrupt line (I2C or SPI).
+ * @lock: Mutex to protect read and write operations.
+ * @fifo_lock: Mutex to prevent concurrent access to the hw FIFO.
+ * @fifo_mode: FIFO operating mode supported by the device.
+ * @enable_mask: Enabled sensor bitmask.
+ * @sip: Total number of samples (acc/gyro) in a given pattern.
+ * @iio_devs: Pointers to acc/gyro iio_dev instances.
+ * @settings: Pointer to the specific sensor settings in use.
+ * @tf: Transfer function structure used by I/O operations.
+ * @tb: Transfer buffers used by SPI I/O operations.
+ */
+struct st_lsm6dsx_hw {
+	struct device *dev;
+	int irq;
+
+	struct mutex lock;
+	struct mutex fifo_lock;
+
+	enum st_lsm6dsx_fifo_mode fifo_mode;
+	u8 enable_mask;
+	u8 sip;
+
+	struct iio_dev *iio_devs[ST_LSM6DSX_ID_MAX];
+
+	const struct st_lsm6dsx_settings *settings;
+
+	const struct st_lsm6dsx_transfer_function *tf;
+#if defined(CONFIG_SPI_MASTER)
+	struct st_lsm6dsx_transfer_buffer tb;
+#endif /* CONFIG_SPI_MASTER */
+};
+
+int st_lsm6dsx_probe(struct device *dev, int irq, int hw_id,
+		     const struct st_lsm6dsx_transfer_function *tf_ops);
+int st_lsm6dsx_sensor_enable(struct st_lsm6dsx_sensor *sensor);
+int st_lsm6dsx_sensor_disable(struct st_lsm6dsx_sensor *sensor);
+int st_lsm6dsx_fifo_setup(struct st_lsm6dsx_hw *hw);
+int st_lsm6dsx_write_with_mask(struct st_lsm6dsx_hw *hw, u8 addr, u8 mask,
+			       u8 val);
+int st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor *sensor,
+				u16 watermark);
+
+#endif /* ST_LSM6DSX_H */

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c

+/*
+ * 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 & ~ST_LSM6DSX_FIFO_TH_MASK) << 8) |
+			  (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;
+}

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c

+/*
+ * STMicroelectronics st_lsm6dsx sensor driver
+ *
+ * The ST LSM6DSx IMU MEMS series consists of 3D digital accelerometer
+ * and 3D digital gyroscope system-in-package with a digital I2C/SPI serial
+ * interface standard output.
+ * LSM6DSx IMU MEMS series has a dynamic user-selectable full-scale
+ * acceleration range of +-2/+-4/+-8/+-16 g and an angular rate range of
+ * +-125/+-245/+-500/+-1000/+-2000 dps
+ * LSM6DSx series has an integrated First-In-First-Out (FIFO) buffer
+ * allowing dynamic batching of sensor data.
+ *
+ * Supported sensors:
+ * - LSM6DS3:
+ *   - Accelerometer/Gyroscope supported ODR [Hz]: 13, 26, 52, 104, 208, 416
+ *   - Accelerometer supported full-scale [g]: +-2/+-4/+-8/+-16
+ *   - Gyroscope supported full-scale [dps]: +-125/+-245/+-500/+-1000/+-2000
+ *   - FIFO size: 8KB
+ *
+ * - LSM6DSM:
+ *   - Accelerometer/Gyroscope supported ODR [Hz]: 13, 26, 52, 104, 208, 416
+ *   - Accelerometer supported full-scale [g]: +-2/+-4/+-8/+-16
+ *   - Gyroscope supported full-scale [dps]: +-125/+-245/+-500/+-1000/+-2000
+ *   - FIFO size: 4KB
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi@st.com>
+ * Denis Ciocca <denis.ciocca@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#include "st_lsm6dsx.h"
+
+#define ST_LSM6DSX_REG_ACC_DEC_MASK		GENMASK(2, 0)
+#define ST_LSM6DSX_REG_GYRO_DEC_MASK		GENMASK(5, 3)
+#define ST_LSM6DSX_REG_INT1_ADDR		0x0d
+#define ST_LSM6DSX_REG_FIFO_FTH_IRQ_MASK	BIT(3)
+#define ST_LSM6DSX_REG_WHOAMI_ADDR		0x0f
+#define ST_LSM6DSX_REG_RESET_ADDR		0x12
+#define ST_LSM6DSX_REG_RESET_MASK		BIT(0)
+#define ST_LSM6DSX_REG_BDU_ADDR			0x12
+#define ST_LSM6DSX_REG_BDU_MASK			BIT(6)
+#define ST_LSM6DSX_REG_INT2_ON_INT1_ADDR	0x13
+#define ST_LSM6DSX_REG_INT2_ON_INT1_MASK	BIT(5)
+#define ST_LSM6DSX_REG_ROUNDING_ADDR		0x16
+#define ST_LSM6DSX_REG_ROUNDING_MASK		BIT(2)
+#define ST_LSM6DSX_REG_LIR_ADDR			0x58
+#define ST_LSM6DSX_REG_LIR_MASK			BIT(0)
+
+#define ST_LSM6DSX_REG_ACC_ODR_ADDR		0x10
+#define ST_LSM6DSX_REG_ACC_ODR_MASK		GENMASK(7, 4)
+#define ST_LSM6DSX_REG_ACC_FS_ADDR		0x10
+#define ST_LSM6DSX_REG_ACC_FS_MASK		GENMASK(3, 2)
+#define ST_LSM6DSX_REG_ACC_OUT_X_L_ADDR		0x28
+#define ST_LSM6DSX_REG_ACC_OUT_Y_L_ADDR		0x2a
+#define ST_LSM6DSX_REG_ACC_OUT_Z_L_ADDR		0x2c
+
+#define ST_LSM6DSX_REG_GYRO_ODR_ADDR		0x11
+#define ST_LSM6DSX_REG_GYRO_ODR_MASK		GENMASK(7, 4)
+#define ST_LSM6DSX_REG_GYRO_FS_ADDR		0x11
+#define ST_LSM6DSX_REG_GYRO_FS_MASK		GENMASK(3, 2)
+#define ST_LSM6DSX_REG_GYRO_OUT_X_L_ADDR	0x22
+#define ST_LSM6DSX_REG_GYRO_OUT_Y_L_ADDR	0x24
+#define ST_LSM6DSX_REG_GYRO_OUT_Z_L_ADDR	0x26
+
+#define ST_LSM6DS3_WHOAMI			0x69
+#define ST_LSM6DSM_WHOAMI			0x6a
+
+#define ST_LSM6DS3_MAX_FIFO_SIZE		8192
+#define ST_LSM6DSM_MAX_FIFO_SIZE		4096
+
+#define ST_LSM6DSX_ACC_FS_2G_GAIN		IIO_G_TO_M_S_2(61)
+#define ST_LSM6DSX_ACC_FS_4G_GAIN		IIO_G_TO_M_S_2(122)
+#define ST_LSM6DSX_ACC_FS_8G_GAIN		IIO_G_TO_M_S_2(244)
+#define ST_LSM6DSX_ACC_FS_16G_GAIN		IIO_G_TO_M_S_2(488)
+
+#define ST_LSM6DSX_GYRO_FS_245_GAIN		IIO_DEGREE_TO_RAD(4375)
+#define ST_LSM6DSX_GYRO_FS_500_GAIN		IIO_DEGREE_TO_RAD(8750)
+#define ST_LSM6DSX_GYRO_FS_1000_GAIN		IIO_DEGREE_TO_RAD(17500)
+#define ST_LSM6DSX_GYRO_FS_2000_GAIN		IIO_DEGREE_TO_RAD(70000)
+
+struct st_lsm6dsx_odr {
+	u16 hz;
+	u8 val;
+};
+
+#define ST_LSM6DSX_ODR_LIST_SIZE	6
+struct st_lsm6dsx_odr_table_entry {
+	struct st_lsm6dsx_reg reg;
+	struct st_lsm6dsx_odr odr_avl[ST_LSM6DSX_ODR_LIST_SIZE];
+};
+
+static const struct st_lsm6dsx_odr_table_entry st_lsm6dsx_odr_table[] = {
+	[ST_LSM6DSX_ID_ACC] = {
+		.reg = {
+			.addr = ST_LSM6DSX_REG_ACC_ODR_ADDR,
+			.mask = ST_LSM6DSX_REG_ACC_ODR_MASK,
+		},
+		.odr_avl[0] = {  13, 0x01 },
+		.odr_avl[1] = {  26, 0x02 },
+		.odr_avl[2] = {  52, 0x03 },
+		.odr_avl[3] = { 104, 0x04 },
+		.odr_avl[4] = { 208, 0x05 },
+		.odr_avl[5] = { 416, 0x06 },
+	},
+	[ST_LSM6DSX_ID_GYRO] = {
+		.reg = {
+			.addr = ST_LSM6DSX_REG_GYRO_ODR_ADDR,
+			.mask = ST_LSM6DSX_REG_GYRO_ODR_MASK,
+		},
+		.odr_avl[0] = {  13, 0x01 },
+		.odr_avl[1] = {  26, 0x02 },
+		.odr_avl[2] = {  52, 0x03 },
+		.odr_avl[3] = { 104, 0x04 },
+		.odr_avl[4] = { 208, 0x05 },
+		.odr_avl[5] = { 416, 0x06 },
+	}
+};
+
+struct st_lsm6dsx_fs {
+	u32 gain;
+	u8 val;
+};
+
+#define ST_LSM6DSX_FS_LIST_SIZE		4
+struct st_lsm6dsx_fs_table_entry {
+	struct st_lsm6dsx_reg reg;
+	struct st_lsm6dsx_fs fs_avl[ST_LSM6DSX_FS_LIST_SIZE];
+};
+
+static const struct st_lsm6dsx_fs_table_entry st_lsm6dsx_fs_table[] = {
+	[ST_LSM6DSX_ID_ACC] = {
+		.reg = {
+			.addr = ST_LSM6DSX_REG_ACC_FS_ADDR,
+			.mask = ST_LSM6DSX_REG_ACC_FS_MASK,
+		},
+		.fs_avl[0] = {  ST_LSM6DSX_ACC_FS_2G_GAIN, 0x0 },
+		.fs_avl[1] = {  ST_LSM6DSX_ACC_FS_4G_GAIN, 0x2 },
+		.fs_avl[2] = {  ST_LSM6DSX_ACC_FS_8G_GAIN, 0x3 },
+		.fs_avl[3] = { ST_LSM6DSX_ACC_FS_16G_GAIN, 0x1 },
+	},
+	[ST_LSM6DSX_ID_GYRO] = {
+		.reg = {
+			.addr = ST_LSM6DSX_REG_GYRO_FS_ADDR,
+			.mask = ST_LSM6DSX_REG_GYRO_FS_MASK,
+		},
+		.fs_avl[0] = {  ST_LSM6DSX_GYRO_FS_245_GAIN, 0x0 },
+		.fs_avl[1] = {  ST_LSM6DSX_GYRO_FS_500_GAIN, 0x1 },
+		.fs_avl[2] = { ST_LSM6DSX_GYRO_FS_1000_GAIN, 0x2 },
+		.fs_avl[3] = { ST_LSM6DSX_GYRO_FS_2000_GAIN, 0x3 },
+	}
+};
+
+static const struct st_lsm6dsx_settings st_lsm6dsx_sensor_settings[] = {
+	{
+		.wai = ST_LSM6DS3_WHOAMI,
+		.max_fifo_size = ST_LSM6DS3_MAX_FIFO_SIZE,
+		.id = ST_LSM6DS3_ID,
+	},
+	{
+		.wai = ST_LSM6DSM_WHOAMI,
+		.max_fifo_size = ST_LSM6DSM_MAX_FIFO_SIZE,
+		.id = ST_LSM6DSM_ID,
+	},
+};
+
+#define ST_LSM6DSX_CHANNEL(chan_type, addr, mod, scan_idx)		\
+{									\
+	.type = chan_type,						\
+	.address = addr,						\
+	.modified = 1,							\
+	.channel2 = mod,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
+			      BIT(IIO_CHAN_INFO_SCALE),			\
+	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = scan_idx,						\
+	.scan_type = {							\
+		.sign = 's',						\
+		.realbits = 16,						\
+		.storagebits = 16,					\
+		.endianness = IIO_LE,					\
+	},								\
+}
+
+static const struct iio_chan_spec st_lsm6dsx_acc_channels[] = {
+	ST_LSM6DSX_CHANNEL(IIO_ACCEL, ST_LSM6DSX_REG_ACC_OUT_X_L_ADDR,
+			   IIO_MOD_X, 0),
+	ST_LSM6DSX_CHANNEL(IIO_ACCEL, ST_LSM6DSX_REG_ACC_OUT_Y_L_ADDR,
+			   IIO_MOD_Y, 1),
+	ST_LSM6DSX_CHANNEL(IIO_ACCEL, ST_LSM6DSX_REG_ACC_OUT_Z_L_ADDR,
+			   IIO_MOD_Z, 2),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+static const struct iio_chan_spec st_lsm6dsx_gyro_channels[] = {
+	ST_LSM6DSX_CHANNEL(IIO_ANGL_VEL, ST_LSM6DSX_REG_GYRO_OUT_X_L_ADDR,
+			   IIO_MOD_X, 0),
+	ST_LSM6DSX_CHANNEL(IIO_ANGL_VEL, ST_LSM6DSX_REG_GYRO_OUT_Y_L_ADDR,
+			   IIO_MOD_Y, 1),
+	ST_LSM6DSX_CHANNEL(IIO_ANGL_VEL, ST_LSM6DSX_REG_GYRO_OUT_Z_L_ADDR,
+			   IIO_MOD_Z, 2),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+int st_lsm6dsx_write_with_mask(struct st_lsm6dsx_hw *hw, u8 addr, u8 mask,
+			       u8 val)
+{
+	u8 data;
+	int err;
+
+	mutex_lock(&hw->lock);
+
+	err = hw->tf->read(hw->dev, addr, sizeof(data), &data);
+	if (err < 0) {
+		dev_err(hw->dev, "failed to read %02x register\n", addr);
+		goto out;
+	}
+
+	data = (data & ~mask) | ((val << __ffs(mask)) & mask);
+
+	err = hw->tf->write(hw->dev, addr, sizeof(data), &data);
+	if (err < 0)
+		dev_err(hw->dev, "failed to write %02x register\n", addr);
+
+out:
+	mutex_unlock(&hw->lock);
+
+	return err;
+}
+
+static int st_lsm6dsx_check_whoami(struct st_lsm6dsx_hw *hw, int id)
+{
+	int err, i;
+	u8 data;
+
+	for (i = 0; i < ARRAY_SIZE(st_lsm6dsx_sensor_settings); i++) {
+		if (id == st_lsm6dsx_sensor_settings[i].id)
+			break;
+	}
+
+	if (i == ARRAY_SIZE(st_lsm6dsx_sensor_settings)) {
+		dev_err(hw->dev, "unsupported hw id [%02x]\n", id);
+		return -ENODEV;
+	}
+
+	err = hw->tf->read(hw->dev, ST_LSM6DSX_REG_WHOAMI_ADDR, sizeof(data),
+			   &data);
+	if (err < 0) {
+		dev_err(hw->dev, "failed to read whoami register\n");
+		return err;
+	}
+
+	if (data != st_lsm6dsx_sensor_settings[i].wai) {
+		dev_err(hw->dev, "unsupported whoami [%02x]\n", data);
+		return -ENODEV;
+	}
+
+	hw->settings = &st_lsm6dsx_sensor_settings[i];
+
+	return 0;
+}
+
+static int st_lsm6dsx_set_full_scale(struct st_lsm6dsx_sensor *sensor,
+				     u32 gain)
+{
+	enum st_lsm6dsx_sensor_id id = sensor->id;
+	int i, err;
+	u8 val;
+
+	for (i = 0; i < ST_LSM6DSX_FS_LIST_SIZE; i++)
+		if (st_lsm6dsx_fs_table[id].fs_avl[i].gain == gain)
+			break;
+
+	if (i == ST_LSM6DSX_FS_LIST_SIZE)
+		return -EINVAL;
+
+	val = st_lsm6dsx_fs_table[id].fs_avl[i].val;
+	err = st_lsm6dsx_write_with_mask(sensor->hw,
+					 st_lsm6dsx_fs_table[id].reg.addr,
+					 st_lsm6dsx_fs_table[id].reg.mask,
+					 val);
+	if (err < 0)
+		return err;
+
+	sensor->gain = gain;
+
+	return 0;
+}
+
+static int st_lsm6dsx_set_odr(struct st_lsm6dsx_sensor *sensor, u16 odr)
+{
+	enum st_lsm6dsx_sensor_id id = sensor->id;
+	int i, err;
+	u8 val;
+
+	for (i = 0; i < ST_LSM6DSX_ODR_LIST_SIZE; i++)
+		if (st_lsm6dsx_odr_table[id].odr_avl[i].hz == odr)
+			break;
+
+	if (i == ST_LSM6DSX_ODR_LIST_SIZE)
+		return -EINVAL;
+
+	val = st_lsm6dsx_odr_table[id].odr_avl[i].val;
+	err = st_lsm6dsx_write_with_mask(sensor->hw,
+					 st_lsm6dsx_odr_table[id].reg.addr,
+					 st_lsm6dsx_odr_table[id].reg.mask,
+					 val);
+	if (err < 0)
+		return err;
+
+	sensor->odr = odr;
+
+	return 0;
+}
+
+int st_lsm6dsx_sensor_enable(struct st_lsm6dsx_sensor *sensor)
+{
+	int err;
+
+	err = st_lsm6dsx_set_odr(sensor, sensor->odr);
+	if (err < 0)
+		return err;
+
+	sensor->hw->enable_mask |= BIT(sensor->id);
+
+	return 0;
+}
+
+int st_lsm6dsx_sensor_disable(struct st_lsm6dsx_sensor *sensor)
+{
+	enum st_lsm6dsx_sensor_id id = sensor->id;
+	int err;
+
+	err = st_lsm6dsx_write_with_mask(sensor->hw,
+					 st_lsm6dsx_odr_table[id].reg.addr,
+					 st_lsm6dsx_odr_table[id].reg.mask, 0);
+	if (err < 0)
+		return err;
+
+	sensor->hw->enable_mask &= ~BIT(id);
+
+	return 0;
+}
+
+static int st_lsm6dsx_read_oneshot(struct st_lsm6dsx_sensor *sensor,
+				   u8 addr, int *val)
+{
+	int err, delay;
+	__le16 data;
+
+	err = st_lsm6dsx_sensor_enable(sensor);
+	if (err < 0)
+		return err;
+
+	delay = 1000000 / sensor->odr;
+	usleep_range(delay, 2 * delay);
+
+	err = sensor->hw->tf->read(sensor->hw->dev, addr, sizeof(data),
+				   (u8 *)&data);
+	if (err < 0)
+		return err;
+
+	st_lsm6dsx_sensor_disable(sensor);
+
+	*val = (s16)data;
+
+	return IIO_VAL_INT;
+}
+
+static int st_lsm6dsx_read_raw(struct iio_dev *iio_dev,
+			       struct iio_chan_spec const *ch,
+			       int *val, int *val2, long mask)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = iio_device_claim_direct_mode(iio_dev);
+		if (ret)
+			break;
+
+		ret = st_lsm6dsx_read_oneshot(sensor, ch->address, val);
+		iio_device_release_direct_mode(iio_dev);
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = sensor->odr;
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = sensor->gain;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int st_lsm6dsx_write_raw(struct iio_dev *iio_dev,
+				struct iio_chan_spec const *chan,
+				int val, int val2, long mask)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
+	int err;
+
+	err = iio_device_claim_direct_mode(iio_dev);
+	if (err)
+		return err;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		err = st_lsm6dsx_set_full_scale(sensor, val2);
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		err = st_lsm6dsx_set_odr(sensor, val);
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	iio_device_release_direct_mode(iio_dev);
+
+	return err;
+}
+
+static int st_lsm6dsx_set_watermark(struct iio_dev *iio_dev, unsigned int val)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(iio_dev);
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	int err, max_fifo_len;
+
+	max_fifo_len = hw->settings->max_fifo_size / ST_LSM6DSX_SAMPLE_SIZE;
+	if (val < 1 || val > max_fifo_len)
+		return -EINVAL;
+
+	err = st_lsm6dsx_update_watermark(sensor, val);
+	if (err < 0)
+		return err;
+
+	sensor->watermark = val;
+
+	return 0;
+}
+
+static ssize_t
+st_lsm6dsx_sysfs_sampling_frequency_avail(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(dev_get_drvdata(dev));
+	enum st_lsm6dsx_sensor_id id = sensor->id;
+	int i, len = 0;
+
+	for (i = 0; i < ST_LSM6DSX_ODR_LIST_SIZE; i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
+				 st_lsm6dsx_odr_table[id].odr_avl[i].hz);
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t st_lsm6dsx_sysfs_scale_avail(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(dev_get_drvdata(dev));
+	enum st_lsm6dsx_sensor_id id = sensor->id;
+	int i, len = 0;
+
+	for (i = 0; i < ST_LSM6DSX_FS_LIST_SIZE; i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06u ",
+				 st_lsm6dsx_fs_table[id].fs_avl[i].gain);
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(st_lsm6dsx_sysfs_sampling_frequency_avail);
+static IIO_DEVICE_ATTR(in_accel_scale_available, 0444,
+		       st_lsm6dsx_sysfs_scale_avail, NULL, 0);
+static IIO_DEVICE_ATTR(in_anglvel_scale_available, 0444,
+		       st_lsm6dsx_sysfs_scale_avail, NULL, 0);
+
+static struct attribute *st_lsm6dsx_acc_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group st_lsm6dsx_acc_attribute_group = {
+	.attrs = st_lsm6dsx_acc_attributes,
+};
+
+static const struct iio_info st_lsm6dsx_acc_info = {
+	.driver_module = THIS_MODULE,
+	.attrs = &st_lsm6dsx_acc_attribute_group,
+	.read_raw = st_lsm6dsx_read_raw,
+	.write_raw = st_lsm6dsx_write_raw,
+	.hwfifo_set_watermark = st_lsm6dsx_set_watermark,
+};
+
+static struct attribute *st_lsm6dsx_gyro_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_in_anglvel_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group st_lsm6dsx_gyro_attribute_group = {
+	.attrs = st_lsm6dsx_gyro_attributes,
+};
+
+static const struct iio_info st_lsm6dsx_gyro_info = {
+	.driver_module = THIS_MODULE,
+	.attrs = &st_lsm6dsx_gyro_attribute_group,
+	.read_raw = st_lsm6dsx_read_raw,
+	.write_raw = st_lsm6dsx_write_raw,
+	.hwfifo_set_watermark = st_lsm6dsx_set_watermark,
+};
+
+static const unsigned long st_lsm6dsx_available_scan_masks[] = {0x7, 0x0};
+
+static int st_lsm6dsx_init_device(struct st_lsm6dsx_hw *hw)
+{
+	int err;
+	u8 data;
+
+	data = ST_LSM6DSX_REG_RESET_MASK;
+	err = hw->tf->write(hw->dev, ST_LSM6DSX_REG_RESET_ADDR, sizeof(data),
+			    &data);
+	if (err < 0)
+		return err;
+
+	msleep(200);
+
+	/* latch interrupts */
+	err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_LIR_ADDR,
+					 ST_LSM6DSX_REG_LIR_MASK, 1);
+	if (err < 0)
+		return err;
+
+	/* enable Block Data Update */
+	err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_BDU_ADDR,
+					 ST_LSM6DSX_REG_BDU_MASK, 1);
+	if (err < 0)
+		return err;
+
+	err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_ROUNDING_ADDR,
+					 ST_LSM6DSX_REG_ROUNDING_MASK, 1);
+	if (err < 0)
+		return err;
+
+	/* enable FIFO watermak interrupt */
+	err = st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_INT1_ADDR,
+					 ST_LSM6DSX_REG_FIFO_FTH_IRQ_MASK, 1);
+	if (err < 0)
+		return err;
+
+	/* redirect INT2 on INT1 */
+	return st_lsm6dsx_write_with_mask(hw, ST_LSM6DSX_REG_INT2_ON_INT1_ADDR,
+					  ST_LSM6DSX_REG_INT2_ON_INT1_MASK, 1);
+}
+
+static struct iio_dev *st_lsm6dsx_alloc_iiodev(struct st_lsm6dsx_hw *hw,
+					       enum st_lsm6dsx_sensor_id id)
+{
+	struct st_lsm6dsx_sensor *sensor;
+	struct iio_dev *iio_dev;
+
+	iio_dev = devm_iio_device_alloc(hw->dev, sizeof(*sensor));
+	if (!iio_dev)
+		return NULL;
+
+	iio_dev->modes = INDIO_DIRECT_MODE;
+	iio_dev->dev.parent = hw->dev;
+	iio_dev->available_scan_masks = st_lsm6dsx_available_scan_masks;
+
+	sensor = iio_priv(iio_dev);
+	sensor->id = id;
+	sensor->hw = hw;
+	sensor->odr = st_lsm6dsx_odr_table[id].odr_avl[0].hz;
+	sensor->gain = st_lsm6dsx_fs_table[id].fs_avl[0].gain;
+	sensor->watermark = 1;
+
+	switch (id) {
+	case ST_LSM6DSX_ID_ACC:
+		iio_dev->channels = st_lsm6dsx_acc_channels;
+		iio_dev->num_channels = ARRAY_SIZE(st_lsm6dsx_acc_channels);
+		iio_dev->name = "lsm6dsx_accel";
+		iio_dev->info = &st_lsm6dsx_acc_info;
+
+		sensor->decimator_mask = ST_LSM6DSX_REG_ACC_DEC_MASK;
+		break;
+	case ST_LSM6DSX_ID_GYRO:
+		iio_dev->channels = st_lsm6dsx_gyro_channels;
+		iio_dev->num_channels = ARRAY_SIZE(st_lsm6dsx_gyro_channels);
+		iio_dev->name = "lsm6dsx_gyro";
+		iio_dev->info = &st_lsm6dsx_gyro_info;
+
+		sensor->decimator_mask = ST_LSM6DSX_REG_GYRO_DEC_MASK;
+		break;
+	default:
+		return NULL;
+	}
+
+	return iio_dev;
+}
+
+int st_lsm6dsx_probe(struct device *dev, int irq, int hw_id,
+		     const struct st_lsm6dsx_transfer_function *tf_ops)
+{
+	struct st_lsm6dsx_hw *hw;
+	int i, err;
+
+	hw = devm_kzalloc(dev, sizeof(*hw), GFP_KERNEL);
+	if (!hw)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, (void *)hw);
+
+	mutex_init(&hw->lock);
+	mutex_init(&hw->fifo_lock);
+
+	hw->dev = dev;
+	hw->irq = irq;
+	hw->tf = tf_ops;
+
+	err = st_lsm6dsx_check_whoami(hw, hw_id);
+	if (err < 0)
+		return err;
+
+	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
+		hw->iio_devs[i] = st_lsm6dsx_alloc_iiodev(hw, i);
+		if (!hw->iio_devs[i])
+			return -ENOMEM;
+	}
+
+	err = st_lsm6dsx_init_device(hw);
+	if (err < 0)
+		return err;
+
+	if (hw->irq > 0) {
+		err = st_lsm6dsx_fifo_setup(hw);
+		if (err < 0)
+			return err;
+	}
+
+	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
+		err = devm_iio_device_register(hw->dev, hw->iio_devs[i]);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(st_lsm6dsx_probe);
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
+MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics st_lsm6dsx driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i2c.c

+/*
+ * STMicroelectronics st_lsm6dsx i2c driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi@st.com>
+ * Denis Ciocca <denis.ciocca@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+#include "st_lsm6dsx.h"
+
+static int st_lsm6dsx_i2c_read(struct device *dev, u8 addr, int len, u8 *data)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct i2c_msg msg[2];
+
+	msg[0].addr = client->addr;
+	msg[0].flags = client->flags;
+	msg[0].len = 1;
+	msg[0].buf = &addr;
+
+	msg[1].addr = client->addr;
+	msg[1].flags = client->flags | I2C_M_RD;
+	msg[1].len = len;
+	msg[1].buf = data;
+
+	return i2c_transfer(client->adapter, msg, 2);
+}
+
+static int st_lsm6dsx_i2c_write(struct device *dev, u8 addr, int len, u8 *data)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct i2c_msg msg;
+	u8 send[len + 1];
+
+	send[0] = addr;
+	memcpy(&send[1], data, len * sizeof(u8));
+
+	msg.addr = client->addr;
+	msg.flags = client->flags;
+	msg.len = len + 1;
+	msg.buf = send;
+
+	return i2c_transfer(client->adapter, &msg, 1);
+}
+
+static const struct st_lsm6dsx_transfer_function st_lsm6dsx_transfer_fn = {
+	.read = st_lsm6dsx_i2c_read,
+	.write = st_lsm6dsx_i2c_write,
+};
+
+static int st_lsm6dsx_i2c_probe(struct i2c_client *client,
+				const struct i2c_device_id *id)
+{
+	return st_lsm6dsx_probe(&client->dev, client->irq,
+				(int)id->driver_data,
+				&st_lsm6dsx_transfer_fn);
+}
+
+static const struct of_device_id st_lsm6dsx_i2c_of_match[] = {
+	{
+		.compatible = "st,lsm6ds3",
+		.data = (void *)ST_LSM6DS3_ID,
+	},
+	{
+		.compatible = "st,lsm6dsm",
+		.data = (void *)ST_LSM6DSM_ID,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, st_lsm6dsx_i2c_of_match);
+
+static const struct i2c_device_id st_lsm6dsx_i2c_id_table[] = {
+	{ ST_LSM6DS3_DEV_NAME, ST_LSM6DS3_ID },
+	{ ST_LSM6DSM_DEV_NAME, ST_LSM6DSM_ID },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, st_lsm6dsx_i2c_id_table);
+
+static struct i2c_driver st_lsm6dsx_driver = {
+	.driver = {
+		.name = "st_lsm6dsx_i2c",
+		.of_match_table = of_match_ptr(st_lsm6dsx_i2c_of_match),
+	},
+	.probe = st_lsm6dsx_i2c_probe,
+	.id_table = st_lsm6dsx_i2c_id_table,
+};
+module_i2c_driver(st_lsm6dsx_driver);
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
+MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics st_lsm6dsx i2c driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_spi.c

+/*
+ * STMicroelectronics st_lsm6dsx spi driver
+ *
+ * Copyright 2016 STMicroelectronics Inc.
+ *
+ * Lorenzo Bianconi <lorenzo.bianconi@st.com>
+ * Denis Ciocca <denis.ciocca@st.com>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+#include "st_lsm6dsx.h"
+
+#define SENSORS_SPI_READ	BIT(7)
+
+static int st_lsm6dsx_spi_read(struct device *dev, u8 addr, int len,
+			       u8 *data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct st_lsm6dsx_hw *hw = spi_get_drvdata(spi);
+	int err;
+
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = hw->tb.tx_buf,
+			.bits_per_word = 8,
+			.len = 1,
+		},
+		{
+			.rx_buf = hw->tb.rx_buf,
+			.bits_per_word = 8,
+			.len = len,
+		}
+	};
+
+	hw->tb.tx_buf[0] = addr | SENSORS_SPI_READ;
+
+	err = spi_sync_transfer(spi, xfers,  ARRAY_SIZE(xfers));
+	if (err < 0)
+		return err;
+
+	memcpy(data, hw->tb.rx_buf, len * sizeof(u8));
+
+	return len;
+}
+
+static int st_lsm6dsx_spi_write(struct device *dev, u8 addr, int len,
+				u8 *data)
+{
+	struct st_lsm6dsx_hw *hw;
+	struct spi_device *spi;
+
+	if (len >= ST_LSM6DSX_TX_MAX_LENGTH)
+		return -ENOMEM;
+
+	spi = to_spi_device(dev);
+	hw = spi_get_drvdata(spi);
+
+	hw->tb.tx_buf[0] = addr;
+	memcpy(&hw->tb.tx_buf[1], data, len);
+
+	return spi_write(spi, hw->tb.tx_buf, len + 1);
+}
+
+static const struct st_lsm6dsx_transfer_function st_lsm6dsx_transfer_fn = {
+	.read = st_lsm6dsx_spi_read,
+	.write = st_lsm6dsx_spi_write,
+};
+
+static int st_lsm6dsx_spi_probe(struct spi_device *spi)
+{
+	const struct spi_device_id *id = spi_get_device_id(spi);
+
+	return st_lsm6dsx_probe(&spi->dev, spi->irq,
+				(int)id->driver_data,
+				&st_lsm6dsx_transfer_fn);
+}
+
+static const struct of_device_id st_lsm6dsx_spi_of_match[] = {
+	{
+		.compatible = "st,lsm6ds3",
+		.data = (void *)ST_LSM6DS3_ID,
+	},
+	{
+		.compatible = "st,lsm6dsm",
+		.data = (void *)ST_LSM6DSM_ID,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, st_lsm6dsx_spi_of_match);
+
+static const struct spi_device_id st_lsm6dsx_spi_id_table[] = {
+	{ ST_LSM6DS3_DEV_NAME, ST_LSM6DS3_ID },
+	{ ST_LSM6DSM_DEV_NAME, ST_LSM6DSM_ID },
+	{},
+};
+MODULE_DEVICE_TABLE(spi, st_lsm6dsx_spi_id_table);
+
+static struct spi_driver st_lsm6dsx_driver = {
+	.driver = {
+		.name = "st_lsm6dsx_spi",
+		.of_match_table = of_match_ptr(st_lsm6dsx_spi_of_match),
+	},
+	.probe = st_lsm6dsx_spi_probe,
+	.id_table = st_lsm6dsx_spi_id_table,
+};
+module_spi_driver(st_lsm6dsx_driver);
+
+MODULE_AUTHOR("Lorenzo Bianconi <lorenzo.bianconi@st.com>");
+MODULE_AUTHOR("Denis Ciocca <denis.ciocca@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics st_lsm6dsx spi driver");
+MODULE_LICENSE("GPL v2");