Re: [PATCH v2 1/9] iio: imu: st_lsm6dsx: introduce locked read/write utility routines

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 11 Nov 2018 15:15:28 +0100
Lorenzo Bianconi <lorenzo.bianconi@redhat.com> wrote:

> Add st_lsm6dsx_update_bits_locked, st_lsm6dsx_read_locked and
> st_lsm6dsx_write_locked utility routines in order to guarantee
> the bus access is atomic respect to reg page configuration.
> This is a preliminary patch to add i2c sensor hub support since
> i2c master registers are accessed through a reg page multiplexer
> 
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
>  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h       | 41 ++++++++++++
>  .../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c    | 63 ++++++++++---------
>  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c  | 24 ++++---
>  3 files changed, 90 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> index ef73519a0fb6..ec204d3b4b1f 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> @@ -148,6 +148,7 @@ struct st_lsm6dsx_sensor {
>   * @irq: Device interrupt line (I2C or SPI).
>   * @fifo_lock: Mutex to prevent concurrent access to the hw FIFO.
>   * @conf_lock: Mutex to prevent concurrent FIFO configuration update.
> + * @page_lock: Mutex to prevent concurrent memory page configuration.
>   * @fifo_mode: FIFO operating mode supported by the device.
>   * @enable_mask: Enabled sensor bitmask.
>   * @ts_sip: Total number of timestamp samples in a given pattern.
> @@ -163,6 +164,7 @@ struct st_lsm6dsx_hw {
>  
>  	struct mutex fifo_lock;
>  	struct mutex conf_lock;
> +	struct mutex page_lock;
>  
>  	enum st_lsm6dsx_fifo_mode fifo_mode;
>  	u8 enable_mask;
> @@ -192,4 +194,43 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw);
>  int st_lsm6dsx_read_tagged_fifo(struct st_lsm6dsx_hw *hw);
>  int st_lsm6dsx_check_odr(struct st_lsm6dsx_sensor *sensor, u16 odr, u8 *val);
>  
> +static inline int
> +st_lsm6dsx_update_bits_locked(struct st_lsm6dsx_hw *hw, unsigned int addr,
> +			      unsigned int mask, unsigned int val)
> +{
> +	int err;
> +
> +	mutex_lock(&hw->page_lock);
> +	err = regmap_update_bits(hw->regmap, addr, mask, val);
> +	mutex_unlock(&hw->page_lock);
> +
> +	return err;
> +}
> +
> +static inline int
> +st_lsm6dsx_read_locked(struct st_lsm6dsx_hw *hw, unsigned int addr,
> +		       void *val, unsigned int len)
> +{
> +	int err;
> +
> +	mutex_lock(&hw->page_lock);
> +	err = regmap_bulk_read(hw->regmap, addr, val, len);
> +	mutex_unlock(&hw->page_lock);
> +
> +	return err;
> +}
> +
> +static inline int
> +st_lsm6dsx_write_locked(struct st_lsm6dsx_hw *hw, unsigned int addr,
> +			unsigned int val)
> +{
> +	int err;
> +
> +	mutex_lock(&hw->page_lock);
> +	err = regmap_write(hw->regmap, addr, val);
> +	mutex_unlock(&hw->page_lock);
> +
> +	return err;
> +}
> +
>  #endif /* ST_LSM6DSX_H */
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> index b5263fc522ca..67cd36bce772 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> @@ -142,8 +142,9 @@ static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
>  		if (dec_reg->addr) {
>  			int val = ST_LSM6DSX_SHIFT_VAL(data, dec_reg->mask);
>  
> -			err = regmap_update_bits(hw->regmap, dec_reg->addr,
> -						 dec_reg->mask, val);
> +			err = st_lsm6dsx_update_bits_locked(hw, dec_reg->addr,
> +							    dec_reg->mask,
> +							    val);
>  			if (err < 0)
>  				return err;
>  		}
> @@ -162,8 +163,8 @@ static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
>  		int val, ts_dec = !!hw->ts_sip;
>  
>  		val = ST_LSM6DSX_SHIFT_VAL(ts_dec, ts_dec_reg->mask);
> -		err = regmap_update_bits(hw->regmap, ts_dec_reg->addr,
> -					 ts_dec_reg->mask, val);
> +		err = st_lsm6dsx_update_bits_locked(hw, ts_dec_reg->addr,
> +						    ts_dec_reg->mask, val);
>  	}
>  	return err;
>  }
> @@ -171,12 +172,12 @@ static int st_lsm6dsx_update_decimators(struct st_lsm6dsx_hw *hw)
>  int st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw *hw,
>  			     enum st_lsm6dsx_fifo_mode fifo_mode)
>  {
> +	unsigned int data;
>  	int err;
>  
> -	err = regmap_update_bits(hw->regmap, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
> -				 ST_LSM6DSX_FIFO_MODE_MASK,
> -				 FIELD_PREP(ST_LSM6DSX_FIFO_MODE_MASK,
> -					    fifo_mode));
> +	data = FIELD_PREP(ST_LSM6DSX_FIFO_MODE_MASK, fifo_mode);
> +	err = st_lsm6dsx_update_bits_locked(hw, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
> +					    ST_LSM6DSX_FIFO_MODE_MASK, data);
>  	if (err < 0)
>  		return err;
>  
> @@ -207,15 +208,15 @@ static int st_lsm6dsx_set_fifo_odr(struct st_lsm6dsx_sensor *sensor,
>  			data = 0;
>  		}
>  		val = ST_LSM6DSX_SHIFT_VAL(data, batch_reg->mask);
> -		return regmap_update_bits(hw->regmap, batch_reg->addr,
> -					  batch_reg->mask, val);
> +		return st_lsm6dsx_update_bits_locked(hw, batch_reg->addr,
> +						     batch_reg->mask, val);
>  	} else {
>  		data = hw->enable_mask ? ST_LSM6DSX_MAX_FIFO_ODR_VAL : 0;
> -		return regmap_update_bits(hw->regmap,
> -					  ST_LSM6DSX_REG_FIFO_MODE_ADDR,
> -					  ST_LSM6DSX_FIFO_ODR_MASK,
> -					  FIELD_PREP(ST_LSM6DSX_FIFO_ODR_MASK,
> -						     data));
> +		return st_lsm6dsx_update_bits_locked(hw,
> +					ST_LSM6DSX_REG_FIFO_MODE_ADDR,
> +					ST_LSM6DSX_FIFO_ODR_MASK,
> +					FIELD_PREP(ST_LSM6DSX_FIFO_ODR_MASK,
> +						   data));
>  	}
>  }
>  
> @@ -246,19 +247,23 @@ int st_lsm6dsx_update_watermark(struct st_lsm6dsx_sensor *sensor, u16 watermark)
>  	fifo_watermark = (fifo_watermark / hw->sip) * hw->sip;
>  	fifo_watermark = fifo_watermark * hw->settings->fifo_ops.th_wl;
>  
> +	mutex_lock(&hw->page_lock);
>  	err = regmap_read(hw->regmap, hw->settings->fifo_ops.fifo_th.addr + 1,
>  			  &data);
>  	if (err < 0)
> -		return err;
> +		goto out;
>  
>  	fifo_th_mask = hw->settings->fifo_ops.fifo_th.mask;
>  	fifo_watermark = ((data << 8) & ~fifo_th_mask) |
>  			 (fifo_watermark & fifo_th_mask);
>  
>  	wdata = cpu_to_le16(fifo_watermark);
> -	return regmap_bulk_write(hw->regmap,
> -				 hw->settings->fifo_ops.fifo_th.addr,
> -				 &wdata, sizeof(wdata));
> +	err = regmap_bulk_write(hw->regmap,
> +				hw->settings->fifo_ops.fifo_th.addr,
> +				&wdata, sizeof(wdata));
> +out:
> +	mutex_unlock(&hw->page_lock);
> +	return err;
>  }
>  
>  static int st_lsm6dsx_reset_hw_ts(struct st_lsm6dsx_hw *hw)
> @@ -267,8 +272,8 @@ static int st_lsm6dsx_reset_hw_ts(struct st_lsm6dsx_hw *hw)
>  	int i, err;
>  
>  	/* reset hw ts counter */
> -	err = regmap_write(hw->regmap, ST_LSM6DSX_REG_TS_RESET_ADDR,
> -			   ST_LSM6DSX_TS_RESET_VAL);
> +	err = st_lsm6dsx_write_locked(hw, ST_LSM6DSX_REG_TS_RESET_ADDR,
> +				      ST_LSM6DSX_TS_RESET_VAL);
>  	if (err < 0)
>  		return err;
>  
> @@ -297,8 +302,8 @@ static inline int st_lsm6dsx_read_block(struct st_lsm6dsx_hw *hw, u8 addr,
>  	while (read_len < data_len) {
>  		word_len = min_t(unsigned int, data_len - read_len,
>  				 max_word_len);
> -		err = regmap_bulk_read(hw->regmap, addr, data + read_len,
> -				       word_len);
> +		err = st_lsm6dsx_read_locked(hw, addr, data + read_len,
> +					     word_len);
>  		if (err < 0)
>  			return err;
>  		read_len += word_len;
> @@ -328,9 +333,9 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
>  	__le16 fifo_status;
>  	s64 ts = 0;
>  
> -	err = regmap_bulk_read(hw->regmap,
> -			       hw->settings->fifo_ops.fifo_diff.addr,
> -			       &fifo_status, sizeof(fifo_status));
> +	err = st_lsm6dsx_read_locked(hw,
> +				     hw->settings->fifo_ops.fifo_diff.addr,
> +				     &fifo_status, sizeof(fifo_status));
>  	if (err < 0) {
>  		dev_err(hw->dev, "failed to read fifo status (err=%d)\n",
>  			err);
> @@ -455,9 +460,9 @@ int st_lsm6dsx_read_tagged_fifo(struct st_lsm6dsx_hw *hw)
>  	__le16 fifo_status;
>  	s64 ts = 0;
>  
> -	err = regmap_bulk_read(hw->regmap,
> -			       hw->settings->fifo_ops.fifo_diff.addr,
> -			       &fifo_status, sizeof(fifo_status));
> +	err = st_lsm6dsx_read_locked(hw,
> +				     hw->settings->fifo_ops.fifo_diff.addr,
> +				     &fifo_status, sizeof(fifo_status));
>  	if (err < 0) {
>  		dev_err(hw->dev, "failed to read fifo status (err=%d)\n",
>  			err);
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> index 2ad3c610e4b6..c8b993bea757 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> @@ -421,6 +421,7 @@ static int st_lsm6dsx_set_full_scale(struct st_lsm6dsx_sensor *sensor,
>  {
>  	struct st_lsm6dsx_hw *hw = sensor->hw;
>  	const struct st_lsm6dsx_reg *reg;
> +	unsigned int data;
>  	int i, err;
>  	u8 val;
>  
> @@ -433,8 +434,8 @@ static int st_lsm6dsx_set_full_scale(struct st_lsm6dsx_sensor *sensor,
>  
>  	val = st_lsm6dsx_fs_table[sensor->id].fs_avl[i].val;
>  	reg = &st_lsm6dsx_fs_table[sensor->id].reg;
> -	err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,
> -				 ST_LSM6DSX_SHIFT_VAL(val, reg->mask));
> +	data = ST_LSM6DSX_SHIFT_VAL(val, reg->mask);
> +	err = st_lsm6dsx_update_bits_locked(hw, reg->addr, reg->mask, data);
>  	if (err < 0)
>  		return err;
>  
> @@ -463,6 +464,7 @@ static int st_lsm6dsx_set_odr(struct st_lsm6dsx_sensor *sensor, u16 odr)
>  {
>  	struct st_lsm6dsx_hw *hw = sensor->hw;
>  	const struct st_lsm6dsx_reg *reg;
> +	unsigned int data;
>  	int err;
>  	u8 val;
>  
> @@ -471,8 +473,8 @@ static int st_lsm6dsx_set_odr(struct st_lsm6dsx_sensor *sensor, u16 odr)
>  		return err;
>  
>  	reg = &st_lsm6dsx_odr_table[sensor->id].reg;
> -	return regmap_update_bits(hw->regmap, reg->addr, reg->mask,
> -				  ST_LSM6DSX_SHIFT_VAL(val, reg->mask));
> +	data = ST_LSM6DSX_SHIFT_VAL(val, reg->mask);
> +	return st_lsm6dsx_update_bits_locked(hw, reg->addr, reg->mask, data);
>  }
>  
>  int st_lsm6dsx_sensor_enable(struct st_lsm6dsx_sensor *sensor)
> @@ -492,11 +494,12 @@ int st_lsm6dsx_sensor_disable(struct st_lsm6dsx_sensor *sensor)
>  {
>  	struct st_lsm6dsx_hw *hw = sensor->hw;
>  	const struct st_lsm6dsx_reg *reg;
> +	unsigned int data;
>  	int err;
>  
>  	reg = &st_lsm6dsx_odr_table[sensor->id].reg;
> -	err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,
> -				 ST_LSM6DSX_SHIFT_VAL(0, reg->mask));
> +	data = ST_LSM6DSX_SHIFT_VAL(0, reg->mask);
> +	err = st_lsm6dsx_update_bits_locked(hw, reg->addr, reg->mask, data);
>  	if (err < 0)
>  		return err;
>  
> @@ -519,7 +522,7 @@ static int st_lsm6dsx_read_oneshot(struct st_lsm6dsx_sensor *sensor,
>  	delay = 1000000 / sensor->odr;
>  	usleep_range(delay, 2 * delay);
>  
> -	err = regmap_bulk_read(hw->regmap, addr, &data, sizeof(data));
> +	err = st_lsm6dsx_read_locked(hw, addr, &data, sizeof(data));
>  	if (err < 0)
>  		return err;
>  
> @@ -865,6 +868,7 @@ int st_lsm6dsx_probe(struct device *dev, int irq, int hw_id, const char *name,
>  
>  	mutex_init(&hw->fifo_lock);
>  	mutex_init(&hw->conf_lock);
> +	mutex_init(&hw->page_lock);
>  
>  	hw->buff = devm_kzalloc(dev, ST_LSM6DSX_BUFF_SIZE, GFP_KERNEL);
>  	if (!hw->buff)
> @@ -909,6 +913,7 @@ static int __maybe_unused st_lsm6dsx_suspend(struct device *dev)
>  	struct st_lsm6dsx_hw *hw = dev_get_drvdata(dev);
>  	struct st_lsm6dsx_sensor *sensor;
>  	const struct st_lsm6dsx_reg *reg;
> +	unsigned int data;
>  	int i, err = 0;
>  
>  	for (i = 0; i < ST_LSM6DSX_ID_MAX; i++) {
> @@ -917,8 +922,9 @@ static int __maybe_unused st_lsm6dsx_suspend(struct device *dev)
>  			continue;
>  
>  		reg = &st_lsm6dsx_odr_table[sensor->id].reg;
> -		err = regmap_update_bits(hw->regmap, reg->addr, reg->mask,
> -					 ST_LSM6DSX_SHIFT_VAL(0, reg->mask));
> +		data = ST_LSM6DSX_SHIFT_VAL(0, reg->mask);
> +		err = st_lsm6dsx_update_bits_locked(hw, reg->addr, reg->mask,
> +						    data);
>  		if (err < 0)
>  			return err;
>  	}