Re: [PATCH] iio: imu: inv_mpu6050: implemented IIO_CHAN_INFO_SAMP_FREQ

[Peter Meerwald-Stadler <pmeerw@pmeerw.net>]

> Moved functionality from IIO_DEV_ATTR_SAMP_FREQ macro into
> IIO_CHAN_INFO_SAMP_FREQ in order to create a generic attribute.
> Modified inv_mpu6050_read_raw and inv_mpu6050_write_raw to allow
> reading and writing the element.

comments below
 
> Signed-off-by: Juliana Rodrigues <juliana.orod@gmail.com>
> ---
>  drivers/iio/imu/inv_mpu6050/inv_mpu_core.c | 187 ++++++++++++++---------------
>  1 file changed, 92 insertions(+), 95 deletions(-)
> 
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> index b9fcbf1..20722c8 100644
> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> @@ -263,6 +263,88 @@ static int inv_mpu6050_sensor_set(struct inv_mpu6050_state  *st, int reg,
>  	return 0;
>  }
>  
> +/**
> + *  inv_mpu6050_set_lpf() - set low pass filer based on fifo rate.

filter

> + *
> + *                  Based on the Nyquist principle, the sampling rate must
> + *                  exceed twice of the bandwidth of the signal, or there
> + *                  would be alising. This function basically search for the

will be
searches

> + *                  correct low pass parameters based on the fifo rate, e.g,

e.g.
but maybe it should be rather i.e.

> + *                  sampling frequency.
> + */
> +static int inv_mpu6050_set_lpf(struct inv_mpu6050_state *st, int rate)
> +{
> +	const int hz[] = {188, 98, 42, 20, 10, 5};
> +	const int d[] = {INV_MPU6050_FILTER_188HZ, INV_MPU6050_FILTER_98HZ,
> +			INV_MPU6050_FILTER_42HZ, INV_MPU6050_FILTER_20HZ,
> +			INV_MPU6050_FILTER_10HZ, INV_MPU6050_FILTER_5HZ};

it is not/only somewhat obvious that hz and d must have the same number of 
entries, could use a #define to make that clear (and could be used 
instead of ARRAY_SIZE)

> +	int i, h, result;
> +	u8 data;
> +
> +	h = (rate >> 1);
> +	i = 0;

i, h could be unsigned
can't we use initialization instead of assignment to save some lines?

> +	while ((h < hz[i]) && (i < ARRAY_SIZE(d) - 1))
> +		i++;
> +	data = d[i];
> +	result = regmap_write(st->map, st->reg->lpf, data);
> +	if (result)
> +		return result;
> +	st->chip_config.lpf = data;
> +
> +	return 0;
> +}
> +
> +/**
> + * inv_mpu6050_write_raw_samp_freq() - Set current raw sampling rate.

frequency is not the same as rate

> + */
> +static int inv_mpu6050_write_raw_samp_freq(struct iio_dev *indio_dev,
> +					   struct inv_mpu6050_state *st,
> +					   int val) {
> +
> +	u8 d;
> +	int result;
> +
> +	if (val < INV_MPU6050_MIN_FIFO_RATE || val > INV_MPU6050_MAX_FIFO_RATE)
> +		return -EINVAL;
> +	if (val == st->chip_config.fifo_rate)
> +		return 0;
> +
> +	mutex_lock(&indio_dev->mlock);
> +	if (st->chip_config.enable) {
> +		result = -EBUSY;
> +		goto fifo_rate_fail;
> +	}
> +
> +	result = inv_mpu6050_set_power_itg(st, true);
> +	if (result)
> +		goto fifo_rate_fail;
> +
> +	d = INV_MPU6050_ONE_K_HZ / val - 1;
> +
> +	result = regmap_write(st->map, st->reg->sample_rate_div, d);
> +

drop newline

> +	if (result)
> +		goto fifo_rate_fail;
> +
> +	st->chip_config.fifo_rate = val;
> +
> +	result = inv_mpu6050_set_lpf(st, val);
> +

drop newline

> +	if (result)
> +		goto fifo_rate_fail;
> +
> +fifo_rate_fail:
> +	result |= inv_mpu6050_set_power_itg(st, false);
> +	mutex_unlock(&indio_dev->mlock);
> +

just
return result;

> +	if (result)
> +		return result;
> +
> +	return 0;
> +
> +}
> +
> +
>  static int inv_mpu6050_sensor_show(struct inv_mpu6050_state  *st, int reg,
>  				   int axis, int *val)
>  {
> @@ -399,6 +481,10 @@ inv_mpu6050_read_raw(struct iio_dev *indio_dev,
>  		default:
>  			return -EINVAL;
>  		}
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = st->chip_config.fifo_rate;
> +
> +		return IIO_VAL_INT;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -511,6 +597,10 @@ static int inv_mpu6050_write_raw(struct iio_dev *indio_dev,
>  		default:
>  			result = -EINVAL;
>  		}
> +		break;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		result = inv_mpu6050_write_raw_samp_freq(indio_dev, st, val);
> +		break;
>  	default:
>  		result = -EINVAL;
>  		break;
> @@ -524,98 +614,6 @@ static int inv_mpu6050_write_raw(struct iio_dev *indio_dev,
>  }
>  
>  /**
> - *  inv_mpu6050_set_lpf() - set low pass filer based on fifo rate.
> - *
> - *                  Based on the Nyquist principle, the sampling rate must
> - *                  exceed twice of the bandwidth of the signal, or there
> - *                  would be alising. This function basically search for the
> - *                  correct low pass parameters based on the fifo rate, e.g,
> - *                  sampling frequency.
> - */
> -static int inv_mpu6050_set_lpf(struct inv_mpu6050_state *st, int rate)
> -{
> -	const int hz[] = {188, 98, 42, 20, 10, 5};
> -	const int d[] = {INV_MPU6050_FILTER_188HZ, INV_MPU6050_FILTER_98HZ,
> -			INV_MPU6050_FILTER_42HZ, INV_MPU6050_FILTER_20HZ,
> -			INV_MPU6050_FILTER_10HZ, INV_MPU6050_FILTER_5HZ};
> -	int i, h, result;
> -	u8 data;
> -
> -	h = (rate >> 1);
> -	i = 0;
> -	while ((h < hz[i]) && (i < ARRAY_SIZE(d) - 1))
> -		i++;
> -	data = d[i];
> -	result = regmap_write(st->map, st->reg->lpf, data);
> -	if (result)
> -		return result;
> -	st->chip_config.lpf = data;
> -
> -	return 0;
> -}
> -
> -/**
> - * inv_mpu6050_fifo_rate_store() - Set fifo rate.
> - */
> -static ssize_t
> -inv_mpu6050_fifo_rate_store(struct device *dev, struct device_attribute *attr,
> -			    const char *buf, size_t count)
> -{
> -	s32 fifo_rate;
> -	u8 d;
> -	int result;
> -	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> -	struct inv_mpu6050_state *st = iio_priv(indio_dev);
> -
> -	if (kstrtoint(buf, 10, &fifo_rate))
> -		return -EINVAL;
> -	if (fifo_rate < INV_MPU6050_MIN_FIFO_RATE ||
> -	    fifo_rate > INV_MPU6050_MAX_FIFO_RATE)
> -		return -EINVAL;
> -	if (fifo_rate == st->chip_config.fifo_rate)
> -		return count;
> -
> -	mutex_lock(&indio_dev->mlock);
> -	if (st->chip_config.enable) {
> -		result = -EBUSY;
> -		goto fifo_rate_fail;
> -	}
> -	result = inv_mpu6050_set_power_itg(st, true);
> -	if (result)
> -		goto fifo_rate_fail;
> -
> -	d = INV_MPU6050_ONE_K_HZ / fifo_rate - 1;
> -	result = regmap_write(st->map, st->reg->sample_rate_div, d);
> -	if (result)
> -		goto fifo_rate_fail;
> -	st->chip_config.fifo_rate = fifo_rate;
> -
> -	result = inv_mpu6050_set_lpf(st, fifo_rate);
> -	if (result)
> -		goto fifo_rate_fail;
> -
> -fifo_rate_fail:
> -	result |= inv_mpu6050_set_power_itg(st, false);
> -	mutex_unlock(&indio_dev->mlock);
> -	if (result)
> -		return result;
> -
> -	return count;
> -}
> -
> -/**
> - * inv_fifo_rate_show() - Get the current sampling rate.
> - */
> -static ssize_t
> -inv_fifo_rate_show(struct device *dev, struct device_attribute *attr,
> -		   char *buf)
> -{
> -	struct inv_mpu6050_state *st = iio_priv(dev_to_iio_dev(dev));
> -
> -	return sprintf(buf, "%d\n", st->chip_config.fifo_rate);
> -}
> -
> -/**
>   * inv_attr_show() - calling this function will show current
>   *                    parameters.
>   *
> @@ -686,6 +684,7 @@ static const struct iio_chan_spec_ext_info inv_ext_info[] = {
>  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	      \
>  				      BIT(IIO_CHAN_INFO_CALIBBIAS),   \
> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
>  		.scan_index = _index,                                 \
>  		.scan_type = {                                        \
>  				.sign = 's',                          \
> @@ -708,6 +707,7 @@ static const struct iio_chan_spec inv_mpu_channels[] = {
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
>  				| BIT(IIO_CHAN_INFO_OFFSET)
>  				| BIT(IIO_CHAN_INFO_SCALE),
> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
>  		.scan_index = -1,
>  	},
>  	INV_MPU6050_CHAN(IIO_ANGL_VEL, IIO_MOD_X, INV_MPU6050_SCAN_GYRO_X),
> @@ -725,8 +725,6 @@ static IIO_CONST_ATTR(in_anglvel_scale_available,
>  					  "0.000133090 0.000266181 0.000532362 0.001064724");
>  static IIO_CONST_ATTR(in_accel_scale_available,
>  					  "0.000598 0.001196 0.002392 0.004785");
> -static IIO_DEV_ATTR_SAMP_FREQ(S_IRUGO | S_IWUSR, inv_fifo_rate_show,
> -	inv_mpu6050_fifo_rate_store);
>  
>  /* Deprecated: kept for userspace backward compatibility. */
>  static IIO_DEVICE_ATTR(in_gyro_matrix, S_IRUGO, inv_attr_show, NULL,
> @@ -737,7 +735,6 @@ static IIO_DEVICE_ATTR(in_accel_matrix, S_IRUGO, inv_attr_show, NULL,
>  static struct attribute *inv_attributes[] = {
>  	&iio_dev_attr_in_gyro_matrix.dev_attr.attr,  /* deprecated */
>  	&iio_dev_attr_in_accel_matrix.dev_attr.attr, /* deprecated */
> -	&iio_dev_attr_sampling_frequency.dev_attr.attr,
>  	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
>  	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
>  	&iio_const_attr_in_anglvel_scale_available.dev_attr.attr,
> 

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)