iio: imu: st_lsm6dsx: add i2c embedded controller support

i2c controller embedded in lsm6dx series can connect up to four
slave devices using accelerometer sensor as trigger for i2c
read/write operations.
Introduce sensor hub support for lsm6dso sensor. Add register map
for lis2mdl magnetometer sensor.
In order to perform single read/write operations st_lsm6dsx driver
relies on SLV0 channel (hw FIFO is not supported yet)

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 702 insertions, 0 deletions

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
new file mode 100644
index 000000000000..9c66e88a1c3a
--- /dev/null
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
@@ -0,0 +1,702 @@
+/*
+ * STMicroelectronics st_lsm6dsx i2c controller driver
+ *
+ * i2c controller embedded in lsm6dx series can connect up to four
+ * slave devices using accelerometer sensor as trigger for i2c
+ * read/write operations. Current implementation relies on SLV0 channel
+ * for slave configuration and SLV{1,2,3} to read data and push them into
+ * the hw FIFO
+ *
+ * Copyright (C) 2018 Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/bitfield.h>
+
+#include "st_lsm6dsx.h"
+
+#define ST_LSM6DSX_MAX_SLV_NUM			3
+#define ST_LSM6DSX_SLV_ADDR(n, base)		((base) + (n) * 3)
+#define ST_LSM6DSX_SLV_SUB_ADDR(n, base)	((base) + 1 + (n) * 3)
+#define ST_LSM6DSX_SLV_CONFIG(n, base)		((base) + 2 + (n) * 3)
+
+#define ST_LS6DSX_READ_OP_MASK			GENMASK(2, 0)
+
+static const struct st_lsm6dsx_ext_dev_settings st_lsm6dsx_ext_dev_table[] = {
+	/* LIS2MDL */
+	{
+		.i2c_addr = { 0x1e },
+		.wai = {
+			.addr = 0x4f,
+			.val = 0x40,
+		},
+		.id = ST_LSM6DSX_ID_MAGN,
+		.odr_table = {
+			.reg = {
+				.addr = 0x60,
+				.mask = GENMASK(3, 2),
+			},
+			.odr_avl[0] = {  10, 0x0 },
+			.odr_avl[1] = {  20, 0x1 },
+			.odr_avl[2] = {  50, 0x2 },
+			.odr_avl[3] = { 100, 0x3 },
+		},
+		.fs_table = {
+			.fs_avl[0] = {
+				.gain = 1500,
+				.val = 0x0,
+			}, /* 1500 uG/LSB */
+		},
+		.temp_comp = {
+			.addr = 0x60,
+			.mask = BIT(7),
+		},
+		.pwr_table = {
+			.reg = {
+				.addr = 0x60,
+				.mask = GENMASK(1, 0),
+			},
+			.off_val = 0x2,
+			.on_val = 0x0,
+		},
+		.off_canc = {
+			.addr = 0x61,
+			.mask = BIT(1),
+		},
+		.bdu = {
+			.addr = 0x62,
+			.mask = BIT(4),
+		},
+		.out = {
+			.addr = 0x68,
+			.len = 6,
+		},
+	},
+};
+
+static void st_lsm6dsx_shub_wait_complete(struct st_lsm6dsx_hw *hw)
+{
+	struct st_lsm6dsx_sensor *sensor;
+
+	sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
+	msleep((2000U / sensor->odr) + 1);
+}
+
+/**
+ * st_lsm6dsx_shub_read_reg - read i2c controller register
+ *
+ * Read st_lsm6dsx i2c controller register
+ */
+static int st_lsm6dsx_shub_read_reg(struct st_lsm6dsx_hw *hw, u8 addr,
+				    u8 *data, int len)
+{
+	const struct st_lsm6dsx_shub_settings *hub_settings;
+	int err;
+
+	mutex_lock(&hw->page_lock);
+
+	hub_settings = &hw->settings->shub_settings;
+	err = st_lsm6dsx_set_page(hw, true);
+	if (err < 0)
+		goto out;
+
+	err = regmap_bulk_read(hw->regmap, addr, data, len);
+
+	st_lsm6dsx_set_page(hw, false);
+out:
+	mutex_unlock(&hw->page_lock);
+
+	return err;
+}
+
+/**
+ * st_lsm6dsx_shub_write_reg - write i2c controller register
+ *
+ * Write st_lsm6dsx i2c controller register
+ */
+static int st_lsm6dsx_shub_write_reg(struct st_lsm6dsx_hw *hw, u8 addr,
+				     u8 *data, int len)
+{
+	int err;
+
+	mutex_lock(&hw->page_lock);
+	err = st_lsm6dsx_set_page(hw, true);
+	if (err < 0)
+		goto out;
+
+	err = regmap_bulk_write(hw->regmap, addr, data, len);
+
+	st_lsm6dsx_set_page(hw, false);
+out:
+	mutex_unlock(&hw->page_lock);
+
+	return err;
+}
+
+static int st_lsm6dsx_shub_master_enable(struct st_lsm6dsx_sensor *sensor,
+					 bool enable)
+{
+	const struct st_lsm6dsx_shub_settings *hub_settings;
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	unsigned int data;
+	int err;
+
+	/* enable acc sensor as trigger */
+	err = st_lsm6dsx_sensor_set_enable(sensor, enable);
+	if (err < 0)
+		return err;
+
+	mutex_lock(&hw->page_lock);
+
+	hub_settings = &hw->settings->shub_settings;
+	err = st_lsm6dsx_set_page(hw, true);
+	if (err < 0)
+		goto out;
+
+	data = ST_LSM6DSX_SHIFT_VAL(enable, hub_settings->master_en.mask);
+	err = regmap_update_bits(hw->regmap, hub_settings->master_en.addr,
+				 hub_settings->master_en.mask, data);
+
+	st_lsm6dsx_set_page(hw, false);
+out:
+	mutex_unlock(&hw->page_lock);
+
+	return err;
+}
+
+/**
+ * st_lsm6dsx_shub_read - read data from slave device register
+ *
+ * Read data from slave device register. SLV0 is used for
+ * one-shot read operation
+ */
+static int
+st_lsm6dsx_shub_read(struct st_lsm6dsx_sensor *sensor, u8 addr,
+		     u8 *data, int len)
+{
+	const struct st_lsm6dsx_shub_settings *hub_settings;
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	u8 config[3], slv_addr;
+	int err;
+
+	hub_settings = &hw->settings->shub_settings;
+	slv_addr = ST_LSM6DSX_SLV_ADDR(0, hub_settings->slv0_addr);
+
+	config[0] = (sensor->ext_info.addr << 1) | 1;
+	config[1] = addr;
+	config[2] = len & ST_LS6DSX_READ_OP_MASK;
+
+	err = st_lsm6dsx_shub_write_reg(hw, slv_addr, config,
+					sizeof(config));
+	if (err < 0)
+		return err;
+
+	err = st_lsm6dsx_shub_master_enable(sensor, true);
+	if (err < 0)
+		return err;
+
+	st_lsm6dsx_shub_wait_complete(hw);
+
+	err = st_lsm6dsx_shub_read_reg(hw, hub_settings->shub_out, data,
+				       len & ST_LS6DSX_READ_OP_MASK);
+
+	st_lsm6dsx_shub_master_enable(sensor, false);
+
+	memset(config, 0, sizeof(config));
+	return st_lsm6dsx_shub_write_reg(hw, slv_addr, config,
+					 sizeof(config));
+}
+
+/**
+ * st_lsm6dsx_shub_write - write data to slave device register
+ *
+ * Write data from slave device register. SLV0 is used for
+ * one-shot write operation
+ */
+static int
+st_lsm6dsx_shub_write(struct st_lsm6dsx_sensor *sensor, u8 addr,
+		      u8 *data, int len)
+{
+	const struct st_lsm6dsx_shub_settings *hub_settings;
+	struct st_lsm6dsx_hw *hw = sensor->hw;
+	u8 config[2], slv_addr;
+	int err, i;
+
+	hub_settings = &hw->settings->shub_settings;
+	slv_addr = ST_LSM6DSX_SLV_ADDR(0, hub_settings->slv0_addr);
+	config[0] = sensor->ext_info.addr << 1;
+	for (i = 0 ; i < len; i++) {
+		config[1] = addr + i;
+
+		err = st_lsm6dsx_shub_write_reg(hw, slv_addr, config,
+						sizeof(config));
+		if (err < 0)
+			return err;
+
+		err = st_lsm6dsx_shub_write_reg(hw, hub_settings->dw_slv0_addr,
+						&data[i], 1);
+		if (err < 0)
+			return err;
+
+		err = st_lsm6dsx_shub_master_enable(sensor, true);
+		if (err < 0)
+			return err;
+
+		st_lsm6dsx_shub_wait_complete(hw);
+
+		st_lsm6dsx_shub_master_enable(sensor, false);
+	}
+
+	memset(config, 0, sizeof(config));
+	return st_lsm6dsx_shub_write_reg(hw, slv_addr, config, sizeof(config));
+}
+
+static int
+st_lsm6dsx_shub_write_with_mask(struct st_lsm6dsx_sensor *sensor,
+				u8 addr, u8 mask, u8 val)
+{
+	int err;
+	u8 data;
+
+	err = st_lsm6dsx_shub_read(sensor, addr, &data, sizeof(data));
+	if (err < 0)
+		return err;
+
+	data = ((data & ~mask) | (val << __ffs(mask) & mask));
+
+	return st_lsm6dsx_shub_write(sensor, addr, &data, sizeof(data));
+}
+
+static int
+st_lsm6dsx_shub_get_odr_val(struct st_lsm6dsx_sensor *sensor,
+			    u16 odr, u16 *val)
+{
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	int i;
+
+	settings = sensor->ext_info.settings;
+	for (i = 0; i < ST_LSM6DSX_ODR_LIST_SIZE; i++)
+		if (settings->odr_table.odr_avl[i].hz == odr)
+			break;
+
+	if (i == ST_LSM6DSX_ODR_LIST_SIZE)
+		return -EINVAL;
+
+	*val = settings->odr_table.odr_avl[i].val;
+	return 0;
+}
+
+static int
+st_lsm6dsx_shub_set_odr(struct st_lsm6dsx_sensor *sensor, u16 odr)
+{
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	u16 val;
+	int err;
+
+	err = st_lsm6dsx_shub_get_odr_val(sensor, odr, &val);
+	if (err < 0)
+		return err;
+
+	settings = sensor->ext_info.settings;
+	return st_lsm6dsx_shub_write_with_mask(sensor,
+					       settings->odr_table.reg.addr,
+					       settings->odr_table.reg.mask,
+					       val);
+}
+
+int st_lsm6dsx_shub_set_enable(struct st_lsm6dsx_sensor *sensor, bool enable)
+{
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	int err;
+
+	settings = sensor->ext_info.settings;
+	if (enable) {
+		err = st_lsm6dsx_shub_set_odr(sensor, sensor->odr);
+		if (err < 0)
+			return err;
+	} else {
+		err = st_lsm6dsx_shub_write_with_mask(sensor,
+					settings->odr_table.reg.addr,
+					settings->odr_table.reg.mask, 0);
+		if (err < 0)
+			return err;
+	}
+
+	if (settings->pwr_table.reg.addr) {
+		u8 val;
+
+		val = enable ? settings->pwr_table.on_val
+			     : settings->pwr_table.off_val;
+		err = st_lsm6dsx_shub_write_with_mask(sensor,
+					settings->pwr_table.reg.addr,
+					settings->pwr_table.reg.mask, val);
+		if (err < 0)
+			return err;
+	}
+
+	return st_lsm6dsx_shub_master_enable(sensor, enable);
+}
+
+static int
+st_lsm6dsx_shub_read_oneshot(struct st_lsm6dsx_sensor *sensor,
+			     struct iio_chan_spec const *ch,
+			     int *val)
+{
+	int err, delay, len = ch->scan_type.realbits >> 3;
+	__le16 data;
+
+	err = st_lsm6dsx_shub_set_enable(sensor, true);
+	if (err < 0)
+		return err;
+
+	delay = 1000000 / sensor->odr;
+	usleep_range(delay, 2 * delay);
+
+	err = st_lsm6dsx_shub_read(sensor, ch->address, (u8 *)&data, len);
+	if (err < 0)
+		return err;
+
+	st_lsm6dsx_shub_set_enable(sensor, false);
+
+	switch (len) {
+	case 2:
+		*val = (s16)le16_to_cpu(data);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return IIO_VAL_INT;
+}
+
+static int
+st_lsm6dsx_shub_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_shub_read_oneshot(sensor, ch, 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_shub_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_SAMP_FREQ: {
+		u16 data;
+
+		err = st_lsm6dsx_shub_get_odr_val(sensor, val, &data);
+		if (!err)
+			sensor->odr = val;
+		break;
+	}
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	iio_device_release_direct_mode(iio_dev);
+
+	return err;
+}
+
+static ssize_t
+st_lsm6dsx_shub_sampling_freq_avail(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(dev_get_drvdata(dev));
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	int i, len = 0;
+
+	settings = sensor->ext_info.settings;
+	for (i = 0; i < ST_LSM6DSX_ODR_LIST_SIZE; i++) {
+		u16 val = settings->odr_table.odr_avl[i].hz;
+
+		if (val > 0)
+			len += scnprintf(buf + len, PAGE_SIZE - len, "%d ",
+					 val);
+	}
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t st_lsm6dsx_shub_scale_avail(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct st_lsm6dsx_sensor *sensor = iio_priv(dev_get_drvdata(dev));
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	int i, len = 0;
+
+	settings = sensor->ext_info.settings;
+	for (i = 0; i < ST_LSM6DSX_FS_LIST_SIZE; i++) {
+		u16 val = settings->fs_table.fs_avl[i].gain;
+
+		if (val > 0)
+			len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06u ",
+					 val);
+	}
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(st_lsm6dsx_shub_sampling_freq_avail);
+static IIO_DEVICE_ATTR(in_scale_available, 0444,
+		       st_lsm6dsx_shub_scale_avail, NULL, 0);
+static struct attribute *st_lsm6dsx_ext_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_in_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group st_lsm6dsx_ext_attribute_group = {
+	.attrs = st_lsm6dsx_ext_attributes,
+};
+
+static const struct iio_info st_lsm6dsx_ext_info = {
+	.attrs = &st_lsm6dsx_ext_attribute_group,
+	.read_raw = st_lsm6dsx_shub_read_raw,
+	.write_raw = st_lsm6dsx_shub_write_raw,
+	.hwfifo_set_watermark = st_lsm6dsx_set_watermark,
+};
+
+static struct iio_dev *
+st_lsm6dsx_shub_alloc_iiodev(struct st_lsm6dsx_hw *hw,
+			     enum st_lsm6dsx_sensor_id id,
+			     const struct st_lsm6dsx_ext_dev_settings *info,
+			     u8 i2c_addr, const char *name)
+{
+	struct iio_chan_spec *ext_channels;
+	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->info = &st_lsm6dsx_ext_info;
+
+	sensor = iio_priv(iio_dev);
+	sensor->id = id;
+	sensor->hw = hw;
+	sensor->odr = info->odr_table.odr_avl[0].hz;
+	sensor->gain = info->fs_table.fs_avl[0].gain;
+	sensor->ext_info.settings = info;
+	sensor->ext_info.addr = i2c_addr;
+	sensor->watermark = 1;
+
+	switch (info->id) {
+	case ST_LSM6DSX_ID_MAGN: {
+		const struct iio_chan_spec magn_channels[] = {
+			ST_LSM6DSX_CHANNEL(IIO_MAGN, info->out.addr,
+					   IIO_MOD_X, 0),
+			ST_LSM6DSX_CHANNEL(IIO_MAGN, info->out.addr + 2,
+					   IIO_MOD_Y, 1),
+			ST_LSM6DSX_CHANNEL(IIO_MAGN, info->out.addr + 4,
+					   IIO_MOD_Z, 2),
+			IIO_CHAN_SOFT_TIMESTAMP(3),
+		};
+
+		ext_channels = devm_kzalloc(hw->dev, sizeof(magn_channels),
+					    GFP_KERNEL);
+		if (!ext_channels)
+			return NULL;
+
+		memcpy(ext_channels, magn_channels, sizeof(magn_channels));
+		iio_dev->available_scan_masks = st_lsm6dsx_available_scan_masks;
+		iio_dev->channels = ext_channels;
+		iio_dev->num_channels = ARRAY_SIZE(magn_channels);
+
+		scnprintf(sensor->name, sizeof(sensor->name), "%s_magn",
+			  name);
+		break;
+	}
+	default:
+		return NULL;
+	}
+	iio_dev->name = sensor->name;
+
+	return iio_dev;
+}
+
+static int st_lsm6dsx_shub_init_device(struct st_lsm6dsx_sensor *sensor)
+{
+	const struct st_lsm6dsx_ext_dev_settings *settings;
+	int err;
+
+	settings = sensor->ext_info.settings;
+	if (settings->bdu.addr) {
+		err = st_lsm6dsx_shub_write_with_mask(sensor,
+						      settings->bdu.addr,
+						      settings->bdu.mask, 1);
+		if (err < 0)
+			return err;
+	}
+
+	if (settings->temp_comp.addr) {
+		err = st_lsm6dsx_shub_write_with_mask(sensor,
+					settings->temp_comp.addr,
+					settings->temp_comp.mask, 1);
+		if (err < 0)
+			return err;
+	}
+
+	if (settings->off_canc.addr) {
+		err = st_lsm6dsx_shub_write_with_mask(sensor,
+					settings->off_canc.addr,
+					settings->off_canc.mask, 1);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+static int
+st_lsm6dsx_shub_check_wai(struct st_lsm6dsx_hw *hw, u8 *i2c_addr,
+			  const struct st_lsm6dsx_ext_dev_settings *settings)
+{
+	const struct st_lsm6dsx_shub_settings *hub_settings;
+	struct st_lsm6dsx_sensor *sensor;
+	u8 config[3], data, slv_addr;
+	bool found = false;
+	int i, err;
+
+	hub_settings = &hw->settings->shub_settings;
+	slv_addr = ST_LSM6DSX_SLV_ADDR(0, hub_settings->slv0_addr);
+	sensor = iio_priv(hw->iio_devs[ST_LSM6DSX_ID_ACC]);
+
+	for (i = 0; i < ARRAY_SIZE(settings->i2c_addr); i++) {
+		if (!settings->i2c_addr[i])
+			continue;
+
+		/* read wai slave register */
+		config[0] = (settings->i2c_addr[i] << 1) | 0x1;
+		config[1] = settings->wai.addr;
+		config[2] = 0x1;
+
+		err = st_lsm6dsx_shub_write_reg(hw, slv_addr, config,
+						sizeof(config));
+		if (err < 0)
+			return err;
+
+		err = st_lsm6dsx_shub_master_enable(sensor, true);
+		if (err < 0)
+			return err;
+
+		st_lsm6dsx_shub_wait_complete(hw);
+
+		err = st_lsm6dsx_shub_read_reg(hw,
+					       hub_settings->shub_out,
+					       &data, sizeof(data));
+
+		st_lsm6dsx_shub_master_enable(sensor, false);
+
+		if (err < 0)
+			return err;
+
+		if (data != settings->wai.val)
+			continue;
+
+		*i2c_addr = settings->i2c_addr[i];
+		found = true;
+		break;
+	}
+
+	/* reset SLV0 channel */
+	memset(config, 0, sizeof(config));
+	err = st_lsm6dsx_shub_write_reg(hw, slv_addr, config,
+					sizeof(config));
+	if (err < 0)
+		return err;
+
+	return found ? 0 : -ENODEV;
+}
+
+int st_lsm6dsx_shub_probe(struct st_lsm6dsx_hw *hw, const char *name)
+{
+	enum st_lsm6dsx_sensor_id id = ST_LSM6DSX_ID_EXT0;
+	struct st_lsm6dsx_sensor *sensor;
+	int err, i, num_ext_dev = 0;
+	u8 i2c_addr = 0;
+
+	for (i = 0; i < ARRAY_SIZE(st_lsm6dsx_ext_dev_table); i++) {
+		err = st_lsm6dsx_shub_check_wai(hw, &i2c_addr,
+					&st_lsm6dsx_ext_dev_table[i]);
+		if (err == -ENODEV)
+			continue;
+		else if (err < 0)
+			return err;
+
+		hw->iio_devs[id] = st_lsm6dsx_shub_alloc_iiodev(hw, id,
+						&st_lsm6dsx_ext_dev_table[i],
+						i2c_addr, name);
+		if (!hw->iio_devs[id])
+			return -ENOMEM;
+
+		sensor = iio_priv(hw->iio_devs[id]);
+		err = st_lsm6dsx_shub_init_device(sensor);
+		if (err < 0)
+			return err;
+
+		if (++num_ext_dev >= ST_LSM6DSX_MAX_SLV_NUM)
+			break;
+		id++;
+	}
+
+	return 0;
+}