Re: [PATCH v2 11/11] iio: make st_sensors drivers use regmap

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 18 Jul 2019 15:53:53 -0700
Denis Ciocca <denis.ciocca@st.com> wrote:

> This patch is meant to replace the i2c/spi transfer functions with
> regmap. SPI framework requires DMA safe buffers so let's add GFP_DMA
> flag for memory allocation used by bulk_read functions.
> 
> Signed-off-by: Denis Ciocca <denis.ciocca@st.com>

Applied, with the appropriate fuzz fixing form the fixup I applied to
patch 10.  Please take a look and make sure I didn't mess this up.

Thanks,

Jonathan

> ---
> Changes in v2:
>  memory allocation uses GFP_DMA if buffer is used in bulk_read
>  fix struct fields doc
> 
>  drivers/iio/accel/st_accel_buffer.c           |   3 +-
>  drivers/iio/accel/st_accel_core.c             |   3 -
>  drivers/iio/accel/st_accel_i2c.c              |   4 +-
>  .../iio/common/st_sensors/st_sensors_buffer.c |  10 +-
>  .../iio/common/st_sensors/st_sensors_core.c   |  41 +++----
>  .../iio/common/st_sensors/st_sensors_i2c.c    |  73 ++++++-------
>  .../iio/common/st_sensors/st_sensors_spi.c    | 100 ++++--------------
>  .../common/st_sensors/st_sensors_trigger.c    |  10 +-
>  drivers/iio/gyro/st_gyro_buffer.c             |   3 +-
>  drivers/iio/gyro/st_gyro_core.c               |   3 -
>  drivers/iio/gyro/st_gyro_i2c.c                |   4 +-
>  drivers/iio/magnetometer/st_magn_buffer.c     |   3 +-
>  drivers/iio/magnetometer/st_magn_core.c       |   3 -
>  drivers/iio/magnetometer/st_magn_i2c.c        |   4 +-
>  drivers/iio/pressure/st_pressure_buffer.c     |   3 +-
>  drivers/iio/pressure/st_pressure_core.c       |   3 -
>  drivers/iio/pressure/st_pressure_i2c.c        |   4 +-
>  include/linux/iio/common/st_sensors.h         |  40 +------
>  include/linux/iio/common/st_sensors_i2c.h     |   4 +-
>  19 files changed, 105 insertions(+), 213 deletions(-)
> 
> diff --git a/drivers/iio/accel/st_accel_buffer.c b/drivers/iio/accel/st_accel_buffer.c
> index 0205c0167cdd..05f9aea431e2 100644
> --- a/drivers/iio/accel/st_accel_buffer.c
> +++ b/drivers/iio/accel/st_accel_buffer.c
> @@ -39,7 +39,8 @@ static int st_accel_buffer_postenable(struct iio_dev *indio_dev)
>  	int err;
>  	struct st_sensor_data *adata = iio_priv(indio_dev);
>  
> -	adata->buffer_data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
> +	adata->buffer_data = kmalloc(indio_dev->scan_bytes,
> +				     GFP_DMA | GFP_KERNEL);
>  	if (adata->buffer_data == NULL) {
>  		err = -ENOMEM;
>  		goto allocate_memory_error;
> diff --git a/drivers/iio/accel/st_accel_core.c b/drivers/iio/accel/st_accel_core.c
> index 630909702a19..0b17004cb12e 100644
> --- a/drivers/iio/accel/st_accel_core.c
> +++ b/drivers/iio/accel/st_accel_core.c
> @@ -13,7 +13,6 @@
>  #include <linux/acpi.h>
>  #include <linux/errno.h>
>  #include <linux/types.h>
> -#include <linux/mutex.h>
>  #include <linux/interrupt.h>
>  #include <linux/i2c.h>
>  #include <linux/gpio.h>
> @@ -1177,7 +1176,6 @@ int st_accel_common_probe(struct iio_dev *indio_dev)
>  
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &accel_info;
> -	mutex_init(&adata->tb.buf_lock);
>  
>  	err = st_sensors_power_enable(indio_dev);
>  	if (err)
> @@ -1188,7 +1186,6 @@ int st_accel_common_probe(struct iio_dev *indio_dev)
>  		goto st_accel_power_off;
>  
>  	adata->num_data_channels = ST_ACCEL_NUMBER_DATA_CHANNELS;
> -	adata->multiread_bit = adata->sensor_settings->multi_read_bit;
>  	indio_dev->num_channels = ST_SENSORS_NUMBER_ALL_CHANNELS;
>  
>  	channels_size = indio_dev->num_channels * sizeof(struct iio_chan_spec);
> diff --git a/drivers/iio/accel/st_accel_i2c.c b/drivers/iio/accel/st_accel_i2c.c
> index a92cf776031e..50fa0fc32baa 100644
> --- a/drivers/iio/accel/st_accel_i2c.c
> +++ b/drivers/iio/accel/st_accel_i2c.c
> @@ -174,7 +174,9 @@ static int st_accel_i2c_probe(struct i2c_client *client)
>  	adata = iio_priv(indio_dev);
>  	adata->sensor_settings = (struct st_sensor_settings *)settings;
>  
> -	st_sensors_i2c_configure(indio_dev, client, adata);
> +	ret = st_sensors_i2c_configure(indio_dev, client);
> +	if (ret < 0)
> +		return ret;
>  
>  	ret = st_accel_common_probe(indio_dev);
>  	if (ret < 0)
> diff --git a/drivers/iio/common/st_sensors/st_sensors_buffer.c b/drivers/iio/common/st_sensors/st_sensors_buffer.c
> index 4a68669dc555..eee30130ae23 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_buffer.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_buffer.c
> @@ -17,15 +17,16 @@
>  #include <linux/iio/trigger_consumer.h>
>  #include <linux/iio/triggered_buffer.h>
>  #include <linux/irqreturn.h>
> +#include <linux/regmap.h>
>  
>  #include <linux/iio/common/st_sensors.h>
>  
>  
>  static int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
>  {
> -	int i;
>  	struct st_sensor_data *sdata = iio_priv(indio_dev);
>  	unsigned int num_data_channels = sdata->num_data_channels;
> +	int i;
>  
>  	for_each_set_bit(i, indio_dev->active_scan_mask, num_data_channels) {
>  		const struct iio_chan_spec *channel = &indio_dev->channels[i];
> @@ -36,11 +37,8 @@ static int st_sensors_get_buffer_element(struct iio_dev *indio_dev, u8 *buf)
>  			channel->scan_type.storagebits >> 3;
>  
>  		buf = PTR_ALIGN(buf, storage_bytes);
> -		if (sdata->tf->read_multiple_byte(&sdata->tb, sdata->dev,
> -						  channel->address,
> -						  bytes_to_read, buf,
> -						  sdata->multiread_bit) <
> -		    bytes_to_read)
> +		if (regmap_bulk_read(sdata->regmap, channel->address,
> +				     buf, bytes_to_read) < 0)
>  			return -EIO;
>  
>  		/* Advance the buffer pointer */
> diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
> index 40977d2ee400..4a3064fb6cd9 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_core.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_core.c
> @@ -15,6 +15,7 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/regmap.h>
>  #include <asm/unaligned.h>
>  #include <linux/iio/common/st_sensors.h>
>  
> @@ -28,19 +29,10 @@ static inline u32 st_sensors_get_unaligned_le24(const u8 *p)
>  int st_sensors_write_data_with_mask(struct iio_dev *indio_dev,
>  				    u8 reg_addr, u8 mask, u8 data)
>  {
> -	int err;
> -	u8 new_data;
>  	struct st_sensor_data *sdata = iio_priv(indio_dev);
>  
> -	err = sdata->tf->read_byte(&sdata->tb, sdata->dev, reg_addr, &new_data);
> -	if (err < 0)
> -		goto st_sensors_write_data_with_mask_error;
> -
> -	new_data = ((new_data & (~mask)) | ((data << __ffs(mask)) & mask));
> -	err = sdata->tf->write_byte(&sdata->tb, sdata->dev, reg_addr, new_data);
> -
> -st_sensors_write_data_with_mask_error:
> -	return err;
> +	return regmap_update_bits(sdata->regmap,
> +				  reg_addr, mask, data << __ffs(mask));
>  }
>  
>  int st_sensors_debugfs_reg_access(struct iio_dev *indio_dev,
> @@ -48,19 +40,15 @@ int st_sensors_debugfs_reg_access(struct iio_dev *indio_dev,
>  				  unsigned *readval)
>  {
>  	struct st_sensor_data *sdata = iio_priv(indio_dev);
> -	u8 readdata;
>  	int err;
>  
>  	if (!readval)
> -		return sdata->tf->write_byte(&sdata->tb, sdata->dev,
> -					     (u8)reg, (u8)writeval);
> +		return regmap_write(sdata->regmap, reg, writeval);
>  
> -	err = sdata->tf->read_byte(&sdata->tb, sdata->dev, (u8)reg, &readdata);
> +	err = regmap_read(sdata->regmap, reg, readval);
>  	if (err < 0)
>  		return err;
>  
> -	*readval = (unsigned)readdata;
> -
>  	return 0;
>  }
>  EXPORT_SYMBOL(st_sensors_debugfs_reg_access);
> @@ -545,7 +533,7 @@ int st_sensors_set_fullscale_by_gain(struct iio_dev *indio_dev, int scale)
>  EXPORT_SYMBOL(st_sensors_set_fullscale_by_gain);
>  
>  static int st_sensors_read_axis_data(struct iio_dev *indio_dev,
> -				struct iio_chan_spec const *ch, int *data)
> +				     struct iio_chan_spec const *ch, int *data)
>  {
>  	int err;
>  	u8 *outdata;
> @@ -554,13 +542,12 @@ static int st_sensors_read_axis_data(struct iio_dev *indio_dev,
>  
>  	byte_for_channel = DIV_ROUND_UP(ch->scan_type.realbits +
>  					ch->scan_type.shift, 8);
> -	outdata = kmalloc(byte_for_channel, GFP_KERNEL);
> +	outdata = kmalloc(byte_for_channel, GFP_DMA | GFP_KERNEL);
>  	if (!outdata)
>  		return -ENOMEM;
>  
> -	err = sdata->tf->read_multiple_byte(&sdata->tb, sdata->dev,
> -				ch->address, byte_for_channel,
> -				outdata, sdata->multiread_bit);
> +	err = regmap_bulk_read(sdata->regmap, ch->address,
> +			       outdata, byte_for_channel);
>  	if (err < 0)
>  		goto st_sensors_free_memory;
>  
> @@ -645,13 +632,11 @@ EXPORT_SYMBOL(st_sensors_get_settings_index);
>  int st_sensors_verify_id(struct iio_dev *indio_dev)
>  {
>  	struct st_sensor_data *sdata = iio_priv(indio_dev);
> -	int err;
> -	u8 wai;
> +	int wai, err;
>  
> -	if (settings->wai_addr) {
> -		err = sdata->tf->read_byte(&sdata->tb, sdata->dev,
> -					   sdata->sensor_settings->wai_addr,
> -					   &wai);
> +	if (sdata->sensor_settings->wai_addr) {
> +		err = regmap_read(sdata->regmap,
> +				  sdata->sensor_settings->wai_addr, &wai);
>  		if (err < 0) {
>  			dev_err(&indio_dev->dev,
>  				"failed to read Who-Am-I register.\n");
> diff --git a/drivers/iio/common/st_sensors/st_sensors_i2c.c b/drivers/iio/common/st_sensors/st_sensors_i2c.c
> index b1c9812407e7..9240625534df 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_i2c.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_i2c.c
> @@ -13,6 +13,7 @@
>  #include <linux/iio/iio.h>
>  #include <linux/of_device.h>
>  #include <linux/acpi.h>
> +#include <linux/regmap.h>
>  
>  #include <linux/iio/common/st_sensors_i2c.h>
>  
> @@ -26,55 +27,51 @@ static unsigned int st_sensors_i2c_get_irq(struct iio_dev *indio_dev)
>  	return to_i2c_client(sdata->dev)->irq;
>  }
>  
> -static int st_sensors_i2c_read_byte(struct st_sensor_transfer_buffer *tb,
> -				struct device *dev, u8 reg_addr, u8 *res_byte)
> -{
> -	int err;
> -
> -	err = i2c_smbus_read_byte_data(to_i2c_client(dev), reg_addr);
> -	if (err < 0)
> -		goto st_accel_i2c_read_byte_error;
> -
> -	*res_byte = err & 0xff;
> -
> -st_accel_i2c_read_byte_error:
> -	return err < 0 ? err : 0;
> -}
> -
> -static int st_sensors_i2c_read_multiple_byte(
> -		struct st_sensor_transfer_buffer *tb, struct device *dev,
> -			u8 reg_addr, int len, u8 *data, bool multiread_bit)
> -{
> -	if (multiread_bit)
> -		reg_addr |= ST_SENSORS_I2C_MULTIREAD;
> -
> -	return i2c_smbus_read_i2c_block_data_or_emulated(to_i2c_client(dev),
> -							 reg_addr, len, data);
> -}
> -
> -static int st_sensors_i2c_write_byte(struct st_sensor_transfer_buffer *tb,
> -				struct device *dev, u8 reg_addr, u8 data)
> -{
> -	return i2c_smbus_write_byte_data(to_i2c_client(dev), reg_addr, data);
> -}
> +static const struct regmap_config st_sensors_i2c_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +};
>  
> -static const struct st_sensor_transfer_function st_sensors_tf_i2c = {
> -	.read_byte = st_sensors_i2c_read_byte,
> -	.write_byte = st_sensors_i2c_write_byte,
> -	.read_multiple_byte = st_sensors_i2c_read_multiple_byte,
> +static const struct regmap_config st_sensors_i2c_regmap_multiread_bit_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.read_flag_mask = ST_SENSORS_I2C_MULTIREAD,
>  };
>  
> -void st_sensors_i2c_configure(struct iio_dev *indio_dev,
> -		struct i2c_client *client, struct st_sensor_data *sdata)
> +/*
> + * st_sensors_i2c_configure() - configure I2C interface
> + * @indio_dev: IIO device reference.
> + * @client: i2c client reference.
> + *
> + * Return: 0 on success, else a negative error code.
> + */
> +int st_sensors_i2c_configure(struct iio_dev *indio_dev,
> +			     struct i2c_client *client)
>  {
> +	struct st_sensor_data *sdata = iio_priv(indio_dev);
> +	const struct regmap_config *config;
> +
> +	if (sdata->sensor_settings->multi_read_bit)
> +		config = &st_sensors_i2c_regmap_multiread_bit_config;
> +	else
> +		config = &st_sensors_i2c_regmap_config;
> +
> +	sdata->regmap = devm_regmap_init_i2c(client, config);
> +	if (IS_ERR(sdata->regmap)) {
> +		dev_err(&client->dev, "Failed to register i2c regmap (%d)\n",
> +			(int)PTR_ERR(sdata->regmap));
> +		return PTR_ERR(sdata->regmap);
> +	}
> +
>  	i2c_set_clientdata(client, indio_dev);
>  
>  	indio_dev->dev.parent = &client->dev;
>  	indio_dev->name = client->name;
>  
>  	sdata->dev = &client->dev;
> -	sdata->tf = &st_sensors_tf_i2c;
>  	sdata->get_irq_data_ready = st_sensors_i2c_get_irq;
> +
> +	return 0;
>  }
>  EXPORT_SYMBOL(st_sensors_i2c_configure);
>  
> diff --git a/drivers/iio/common/st_sensors/st_sensors_spi.c b/drivers/iio/common/st_sensors/st_sensors_spi.c
> index a57cd648975c..9c0661a283d0 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_spi.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_spi.c
> @@ -11,12 +11,12 @@
>  #include <linux/module.h>
>  #include <linux/slab.h>
>  #include <linux/iio/iio.h>
> +#include <linux/regmap.h>
>  
>  #include <linux/iio/common/st_sensors_spi.h>
> -
> +#include "st_sensors_core.h"
>  
>  #define ST_SENSORS_SPI_MULTIREAD	0xc0
> -#define ST_SENSORS_SPI_READ		0x80
>  
>  static unsigned int st_sensors_spi_get_irq(struct iio_dev *indio_dev)
>  {
> @@ -25,81 +25,15 @@ static unsigned int st_sensors_spi_get_irq(struct iio_dev *indio_dev)
>  	return to_spi_device(sdata->dev)->irq;
>  }
>  
> -static int st_sensors_spi_read(struct st_sensor_transfer_buffer *tb,
> -	struct device *dev, u8 reg_addr, int len, u8 *data, bool multiread_bit)
> -{
> -	int err;
> -
> -	struct spi_transfer xfers[] = {
> -		{
> -			.tx_buf = tb->tx_buf,
> -			.bits_per_word = 8,
> -			.len = 1,
> -		},
> -		{
> -			.rx_buf = tb->rx_buf,
> -			.bits_per_word = 8,
> -			.len = len,
> -		}
> -	};
> -
> -	mutex_lock(&tb->buf_lock);
> -	if ((multiread_bit) && (len > 1))
> -		tb->tx_buf[0] = reg_addr | ST_SENSORS_SPI_MULTIREAD;
> -	else
> -		tb->tx_buf[0] = reg_addr | ST_SENSORS_SPI_READ;
> -
> -	err = spi_sync_transfer(to_spi_device(dev), xfers, ARRAY_SIZE(xfers));
> -	if (err)
> -		goto acc_spi_read_error;
> -
> -	memcpy(data, tb->rx_buf, len);
> -	mutex_unlock(&tb->buf_lock);
> -	return len;
> -
> -acc_spi_read_error:
> -	mutex_unlock(&tb->buf_lock);
> -	return err;
> -}
> -
> -static int st_sensors_spi_read_byte(struct st_sensor_transfer_buffer *tb,
> -				struct device *dev, u8 reg_addr, u8 *res_byte)
> -{
> -	return st_sensors_spi_read(tb, dev, reg_addr, 1, res_byte, false);
> -}
> -
> -static int st_sensors_spi_read_multiple_byte(
> -	struct st_sensor_transfer_buffer *tb, struct device *dev,
> -			u8 reg_addr, int len, u8 *data, bool multiread_bit)
> -{
> -	return st_sensors_spi_read(tb, dev, reg_addr, len, data, multiread_bit);
> -}
> -
> -static int st_sensors_spi_write_byte(struct st_sensor_transfer_buffer *tb,
> -				struct device *dev, u8 reg_addr, u8 data)
> -{
> -	int err;
> -
> -	struct spi_transfer xfers = {
> -		.tx_buf = tb->tx_buf,
> -		.bits_per_word = 8,
> -		.len = 2,
> -	};
> -
> -	mutex_lock(&tb->buf_lock);
> -	tb->tx_buf[0] = reg_addr;
> -	tb->tx_buf[1] = data;
> -
> -	err = spi_sync_transfer(to_spi_device(dev), &xfers, 1);
> -	mutex_unlock(&tb->buf_lock);
> -
> -	return err;
> -}
> +static const struct regmap_config st_sensors_spi_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +};
>  
> -static const struct st_sensor_transfer_function st_sensors_tf_spi = {
> -	.read_byte = st_sensors_spi_read_byte,
> -	.write_byte = st_sensors_spi_write_byte,
> -	.read_multiple_byte = st_sensors_spi_read_multiple_byte,
> +static const struct regmap_config st_sensors_spi_regmap_multiread_bit_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.read_flag_mask = ST_SENSORS_SPI_MULTIREAD,
>  };
>  
>  /*
> @@ -155,6 +89,7 @@ int st_sensors_spi_configure(struct iio_dev *indio_dev,
>  			     struct spi_device *spi)
>  {
>  	struct st_sensor_data *sdata = iio_priv(indio_dev);
> +	const struct regmap_config *config;
>  	int err;
>  
>  	if (st_sensors_is_spi_3_wire(spi)) {
> @@ -164,13 +99,24 @@ int st_sensors_spi_configure(struct iio_dev *indio_dev,
>  			return err;
>  	}
>  
> +	if (sdata->sensor_settings->multi_read_bit)
> +		config = &st_sensors_spi_regmap_multiread_bit_config;
> +	else
> +		config = &st_sensors_spi_regmap_config;
> +
> +	sdata->regmap = devm_regmap_init_spi(spi, config);
> +	if (IS_ERR(sdata->regmap)) {
> +		dev_err(&spi->dev, "Failed to register spi regmap (%d)\n",
> +			(int)PTR_ERR(sdata->regmap));
> +		return PTR_ERR(sdata->regmap);
> +	}
> +
>  	spi_set_drvdata(spi, indio_dev);
>  
>  	indio_dev->dev.parent = &spi->dev;
>  	indio_dev->name = spi->modalias;
>  
>  	sdata->dev = &spi->dev;
> -	sdata->tf = &st_sensors_tf_spi;
>  	sdata->get_irq_data_ready = st_sensors_spi_get_irq;
>  
>  	return 0;
> diff --git a/drivers/iio/common/st_sensors/st_sensors_trigger.c b/drivers/iio/common/st_sensors/st_sensors_trigger.c
> index 630c8cb35e8b..bed7b8682b17 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_trigger.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_trigger.c
> @@ -13,6 +13,7 @@
>  #include <linux/iio/iio.h>
>  #include <linux/iio/trigger.h>
>  #include <linux/interrupt.h>
> +#include <linux/regmap.h>
>  #include <linux/iio/common/st_sensors.h>
>  #include "st_sensors_core.h"
>  
> @@ -26,8 +27,7 @@
>  static int st_sensors_new_samples_available(struct iio_dev *indio_dev,
>  					    struct st_sensor_data *sdata)
>  {
> -	u8 status;
> -	int ret;
> +	int ret, status;
>  
>  	/* How would I know if I can't check it? */
>  	if (!sdata->sensor_settings->drdy_irq.stat_drdy.addr)
> @@ -37,9 +37,9 @@ static int st_sensors_new_samples_available(struct iio_dev *indio_dev,
>  	if (!indio_dev->active_scan_mask)
>  		return 0;
>  
> -	ret = sdata->tf->read_byte(&sdata->tb, sdata->dev,
> -			sdata->sensor_settings->drdy_irq.stat_drdy.addr,
> -			&status);
> +	ret = regmap_read(sdata->regmap,
> +			  sdata->sensor_settings->drdy_irq.stat_drdy.addr,
> +			  &status);
>  	if (ret < 0) {
>  		dev_err(sdata->dev,
>  			"error checking samples available\n");
> diff --git a/drivers/iio/gyro/st_gyro_buffer.c b/drivers/iio/gyro/st_gyro_buffer.c
> index 6e362f735e92..21360681d4dd 100644
> --- a/drivers/iio/gyro/st_gyro_buffer.c
> +++ b/drivers/iio/gyro/st_gyro_buffer.c
> @@ -39,7 +39,8 @@ static int st_gyro_buffer_postenable(struct iio_dev *indio_dev)
>  	int err;
>  	struct st_sensor_data *gdata = iio_priv(indio_dev);
>  
> -	gdata->buffer_data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
> +	gdata->buffer_data = kmalloc(indio_dev->scan_bytes,
> +				     GFP_DMA | GFP_KERNEL);
>  	if (gdata->buffer_data == NULL) {
>  		err = -ENOMEM;
>  		goto allocate_memory_error;
> diff --git a/drivers/iio/gyro/st_gyro_core.c b/drivers/iio/gyro/st_gyro_core.c
> index 4b87e79aa744..02e42c945181 100644
> --- a/drivers/iio/gyro/st_gyro_core.c
> +++ b/drivers/iio/gyro/st_gyro_core.c
> @@ -12,7 +12,6 @@
>  #include <linux/slab.h>
>  #include <linux/errno.h>
>  #include <linux/types.h>
> -#include <linux/mutex.h>
>  #include <linux/interrupt.h>
>  #include <linux/i2c.h>
>  #include <linux/gpio.h>
> @@ -394,7 +393,6 @@ int st_gyro_common_probe(struct iio_dev *indio_dev)
>  
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &gyro_info;
> -	mutex_init(&gdata->tb.buf_lock);
>  
>  	err = st_sensors_power_enable(indio_dev);
>  	if (err)
> @@ -405,7 +403,6 @@ int st_gyro_common_probe(struct iio_dev *indio_dev)
>  		goto st_gyro_power_off;
>  
>  	gdata->num_data_channels = ST_GYRO_NUMBER_DATA_CHANNELS;
> -	gdata->multiread_bit = gdata->sensor_settings->multi_read_bit;
>  	indio_dev->channels = gdata->sensor_settings->ch;
>  	indio_dev->num_channels = ST_SENSORS_NUMBER_ALL_CHANNELS;
>  
> diff --git a/drivers/iio/gyro/st_gyro_i2c.c b/drivers/iio/gyro/st_gyro_i2c.c
> index fa71e94b76f4..05a1a0874bd5 100644
> --- a/drivers/iio/gyro/st_gyro_i2c.c
> +++ b/drivers/iio/gyro/st_gyro_i2c.c
> @@ -87,7 +87,9 @@ static int st_gyro_i2c_probe(struct i2c_client *client,
>  	gdata = iio_priv(indio_dev);
>  	gdata->sensor_settings = (struct st_sensor_settings *)settings;
>  
> -	st_sensors_i2c_configure(indio_dev, client, gdata);
> +	err = st_sensors_i2c_configure(indio_dev, client);
> +	if (err < 0)
> +		return err;
>  
>  	err = st_gyro_common_probe(indio_dev);
>  	if (err < 0)
> diff --git a/drivers/iio/magnetometer/st_magn_buffer.c b/drivers/iio/magnetometer/st_magn_buffer.c
> index 11d7806655bc..9dba93539a99 100644
> --- a/drivers/iio/magnetometer/st_magn_buffer.c
> +++ b/drivers/iio/magnetometer/st_magn_buffer.c
> @@ -34,7 +34,8 @@ static int st_magn_buffer_postenable(struct iio_dev *indio_dev)
>  	int err;
>  	struct st_sensor_data *mdata = iio_priv(indio_dev);
>  
> -	mdata->buffer_data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
> +	mdata->buffer_data = kmalloc(indio_dev->scan_bytes,
> +				     GFP_DMA | GFP_KERNEL);
>  	if (mdata->buffer_data == NULL) {
>  		err = -ENOMEM;
>  		goto allocate_memory_error;
> diff --git a/drivers/iio/magnetometer/st_magn_core.c b/drivers/iio/magnetometer/st_magn_core.c
> index 3f313aefece6..804353a483c7 100644
> --- a/drivers/iio/magnetometer/st_magn_core.c
> +++ b/drivers/iio/magnetometer/st_magn_core.c
> @@ -12,7 +12,6 @@
>  #include <linux/slab.h>
>  #include <linux/errno.h>
>  #include <linux/types.h>
> -#include <linux/mutex.h>
>  #include <linux/interrupt.h>
>  #include <linux/i2c.h>
>  #include <linux/gpio.h>
> @@ -496,7 +495,6 @@ int st_magn_common_probe(struct iio_dev *indio_dev)
>  
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &magn_info;
> -	mutex_init(&mdata->tb.buf_lock);
>  
>  	err = st_sensors_power_enable(indio_dev);
>  	if (err)
> @@ -507,7 +505,6 @@ int st_magn_common_probe(struct iio_dev *indio_dev)
>  		goto st_magn_power_off;
>  
>  	mdata->num_data_channels = ST_MAGN_NUMBER_DATA_CHANNELS;
> -	mdata->multiread_bit = mdata->sensor_settings->multi_read_bit;
>  	indio_dev->channels = mdata->sensor_settings->ch;
>  	indio_dev->num_channels = ST_SENSORS_NUMBER_ALL_CHANNELS;
>  
> diff --git a/drivers/iio/magnetometer/st_magn_i2c.c b/drivers/iio/magnetometer/st_magn_i2c.c
> index d5d565639bed..fdba480a12be 100644
> --- a/drivers/iio/magnetometer/st_magn_i2c.c
> +++ b/drivers/iio/magnetometer/st_magn_i2c.c
> @@ -79,7 +79,9 @@ static int st_magn_i2c_probe(struct i2c_client *client,
>  	mdata = iio_priv(indio_dev);
>  	mdata->sensor_settings = (struct st_sensor_settings *)settings;
>  
> -	st_sensors_i2c_configure(indio_dev, client, mdata);
> +	err = st_sensors_i2c_configure(indio_dev, client);
> +	if (err < 0)
> +		return err;
>  
>  	err = st_magn_common_probe(indio_dev);
>  	if (err < 0)
> diff --git a/drivers/iio/pressure/st_pressure_buffer.c b/drivers/iio/pressure/st_pressure_buffer.c
> index 4566e08a64a1..f21b630abaa0 100644
> --- a/drivers/iio/pressure/st_pressure_buffer.c
> +++ b/drivers/iio/pressure/st_pressure_buffer.c
> @@ -39,7 +39,8 @@ static int st_press_buffer_postenable(struct iio_dev *indio_dev)
>  	int err;
>  	struct st_sensor_data *press_data = iio_priv(indio_dev);
>  
> -	press_data->buffer_data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
> +	press_data->buffer_data = kmalloc(indio_dev->scan_bytes,
> +					  GFP_DMA | GFP_KERNEL);
>  	if (press_data->buffer_data == NULL) {
>  		err = -ENOMEM;
>  		goto allocate_memory_error;
> diff --git a/drivers/iio/pressure/st_pressure_core.c b/drivers/iio/pressure/st_pressure_core.c
> index a783fc075c26..9ef92a501286 100644
> --- a/drivers/iio/pressure/st_pressure_core.c
> +++ b/drivers/iio/pressure/st_pressure_core.c
> @@ -12,7 +12,6 @@
>  #include <linux/slab.h>
>  #include <linux/errno.h>
>  #include <linux/types.h>
> -#include <linux/mutex.h>
>  #include <linux/interrupt.h>
>  #include <linux/i2c.h>
>  #include <linux/gpio.h>
> @@ -692,7 +691,6 @@ int st_press_common_probe(struct iio_dev *indio_dev)
>  
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &press_info;
> -	mutex_init(&press_data->tb.buf_lock);
>  
>  	err = st_sensors_power_enable(indio_dev);
>  	if (err)
> @@ -709,7 +707,6 @@ int st_press_common_probe(struct iio_dev *indio_dev)
>  	 * element.
>  	 */
>  	press_data->num_data_channels = press_data->sensor_settings->num_ch - 1;
> -	press_data->multiread_bit = press_data->sensor_settings->multi_read_bit;
>  	indio_dev->channels = press_data->sensor_settings->ch;
>  	indio_dev->num_channels = press_data->sensor_settings->num_ch;
>  
> diff --git a/drivers/iio/pressure/st_pressure_i2c.c b/drivers/iio/pressure/st_pressure_i2c.c
> index 466e7dde5eae..71d2ed6b4948 100644
> --- a/drivers/iio/pressure/st_pressure_i2c.c
> +++ b/drivers/iio/pressure/st_pressure_i2c.c
> @@ -112,7 +112,9 @@ static int st_press_i2c_probe(struct i2c_client *client,
>  	press_data = iio_priv(indio_dev);
>  	press_data->sensor_settings = (struct st_sensor_settings *)settings;
>  
> -	st_sensors_i2c_configure(indio_dev, client, press_data);
> +	ret = st_sensors_i2c_configure(indio_dev, client);
> +	if (ret < 0)
> +		return ret;
>  
>  	ret = st_press_common_probe(indio_dev);
>  	if (ret < 0)
> diff --git a/include/linux/iio/common/st_sensors.h b/include/linux/iio/common/st_sensors.h
> index 566b955e2980..28fc1f9fa7d5 100644
> --- a/include/linux/iio/common/st_sensors.h
> +++ b/include/linux/iio/common/st_sensors.h
> @@ -16,6 +16,7 @@
>  #include <linux/iio/trigger.h>
>  #include <linux/bitops.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/regmap.h>
>  
>  #include <linux/platform_data/st_sensors_pdata.h>
>  
> @@ -169,36 +170,6 @@ struct st_sensor_data_ready_irq {
>  	} ig1;
>  };
>  
> -/**
> - * struct st_sensor_transfer_buffer - ST sensor device I/O buffer
> - * @buf_lock: Mutex to protect rx and tx buffers.
> - * @tx_buf: Buffer used by SPI transfer function to send data to the sensors.
> - *	This buffer is used to avoid DMA not-aligned issue.
> - * @rx_buf: Buffer used by SPI transfer to receive data from sensors.
> - *	This buffer is used to avoid DMA not-aligned issue.
> - */
> -struct st_sensor_transfer_buffer {
> -	struct mutex buf_lock;
> -	u8 rx_buf[ST_SENSORS_RX_MAX_LENGTH];
> -	u8 tx_buf[ST_SENSORS_TX_MAX_LENGTH] ____cacheline_aligned;
> -};
> -
> -/**
> - * struct st_sensor_transfer_function - ST sensor device I/O function
> - * @read_byte: Function used to read one byte.
> - * @write_byte: Function used to write one byte.
> - * @read_multiple_byte: Function used to read multiple byte.
> - */
> -struct st_sensor_transfer_function {
> -	int (*read_byte) (struct st_sensor_transfer_buffer *tb,
> -				struct device *dev, u8 reg_addr, u8 *res_byte);
> -	int (*write_byte) (struct st_sensor_transfer_buffer *tb,
> -				struct device *dev, u8 reg_addr, u8 data);
> -	int (*read_multiple_byte) (struct st_sensor_transfer_buffer *tb,
> -		struct device *dev, u8 reg_addr, int len, u8 *data,
> -							bool multiread_bit);
> -};
> -
>  /**
>   * struct st_sensor_settings - ST specific sensor settings
>   * @wai: Contents of WhoAmI register.
> @@ -242,16 +213,14 @@ struct st_sensor_settings {
>   * @current_fullscale: Maximum range of measure by the sensor.
>   * @vdd: Pointer to sensor's Vdd power supply
>   * @vdd_io: Pointer to sensor's Vdd-IO power supply
> + * @regmap: Pointer to specific sensor regmap configuration.
>   * @enabled: Status of the sensor (false->off, true->on).
> - * @multiread_bit: Use or not particular bit for [I2C/SPI] multiread.
>   * @buffer_data: Data used by buffer part.
>   * @odr: Output data rate of the sensor [Hz].
>   * num_data_channels: Number of data channels used in buffer.
>   * @drdy_int_pin: Redirect DRDY on pin 1 (1) or pin 2 (2).
>   * @int_pin_open_drain: Set the interrupt/DRDY to open drain.
>   * @get_irq_data_ready: Function to get the IRQ used for data ready signal.
> - * @tf: Transfer function structure used by I/O operations.
> - * @tb: Transfer buffers and mutex used by I/O operations.
>   * @edge_irq: the IRQ triggers on edges and need special handling.
>   * @hw_irq_trigger: if we're using the hardware interrupt on the sensor.
>   * @hw_timestamp: Latest timestamp from the interrupt handler, when in use.
> @@ -264,9 +233,9 @@ struct st_sensor_data {
>  	struct st_sensor_fullscale_avl *current_fullscale;
>  	struct regulator *vdd;
>  	struct regulator *vdd_io;
> +	struct regmap *regmap;
>  
>  	bool enabled;
> -	bool multiread_bit;
>  
>  	char *buffer_data;
>  
> @@ -278,9 +247,6 @@ struct st_sensor_data {
>  
>  	unsigned int (*get_irq_data_ready) (struct iio_dev *indio_dev);
>  
> -	const struct st_sensor_transfer_function *tf;
> -	struct st_sensor_transfer_buffer tb;
> -
>  	bool edge_irq;
>  	bool hw_irq_trigger;
>  	s64 hw_timestamp;
> diff --git a/include/linux/iio/common/st_sensors_i2c.h b/include/linux/iio/common/st_sensors_i2c.h
> index 5ada89944698..01e424e2af4f 100644
> --- a/include/linux/iio/common/st_sensors_i2c.h
> +++ b/include/linux/iio/common/st_sensors_i2c.h
> @@ -14,8 +14,8 @@
>  #include <linux/iio/common/st_sensors.h>
>  #include <linux/of.h>
>  
> -void st_sensors_i2c_configure(struct iio_dev *indio_dev,
> -		struct i2c_client *client, struct st_sensor_data *sdata);
> +int st_sensors_i2c_configure(struct iio_dev *indio_dev,
> +			     struct i2c_client *client);
>  
>  #ifdef CONFIG_ACPI
>  int st_sensors_match_acpi_device(struct device *dev);