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SubjectRe: [PATCH v3 6/6] iio:adxl372: Add filter bandwidth support
On Fri, 3 Aug 2018 16:02:21 +0300
Stefan Popa <stefan.popa@analog.com> wrote:

> This patch adds the option for the user to select the filter bandwidth. The
> user can also read the available bandwidths which are always adjusted to be
> at most half of the sampling frequency. Furthermore, the currently selected
> bandwidth can be read via the read_raw function, while the write_raw sets a
> new bandwidth value.
>
> Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Another good one. Same comment as previous :)

Jonathan

> ---
> drivers/iio/accel/adxl372.c | 38 ++++++++++++++++++++++++++++++++++++--
> 1 file changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/accel/adxl372.c b/drivers/iio/accel/adxl372.c
> index 80b1838..3a9d55a 100644
> --- a/drivers/iio/accel/adxl372.c
> +++ b/drivers/iio/accel/adxl372.c
> @@ -196,6 +196,10 @@ static const int adxl372_samp_freq_tbl[5] = {
> 400, 800, 1600, 3200, 6400,
> };
>
> +static const int adxl372_bw_freq_tbl[5] = {
> + 200, 400, 800, 1600, 3200,
> +};
> +
> struct adxl372_axis_lookup {
> unsigned int bits;
> enum adxl372_fifo_format fifo_format;
> @@ -218,7 +222,8 @@ static const struct adxl372_axis_lookup adxl372_axis_lookup_table[] = {
> .channel2 = IIO_MOD_##axis, \
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
> - BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> + BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY), \
> .scan_index = index, \
> .scan_type = { \
> .sign = 's', \
> @@ -656,6 +661,9 @@ static int adxl372_read_raw(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_SAMP_FREQ:
> *val = adxl372_samp_freq_tbl[st->odr];
> return IIO_VAL_INT;
> + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> + *val = adxl372_bw_freq_tbl[st->bw];
> + return IIO_VAL_INT;
> }
>
> return -EINVAL;
> @@ -666,7 +674,7 @@ static int adxl372_write_raw(struct iio_dev *indio_dev,
> int val, int val2, long info)
> {
> struct adxl372_state *st = iio_priv(indio_dev);
> - int odr_index, ret;
> + int odr_index, bw_index, ret;
>
> switch (info) {
> case IIO_CHAN_INFO_SAMP_FREQ:
> @@ -698,11 +706,34 @@ static int adxl372_write_raw(struct iio_dev *indio_dev,
> ret = adxl372_set_bandwidth(st, odr_index);
>
> return ret;
> + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> + bw_index = adxl372_find_closest_match(adxl372_bw_freq_tbl,
> + ARRAY_SIZE(adxl372_bw_freq_tbl),
> + val);
> + return adxl372_set_bandwidth(st, bw_index);
> default:
> return -EINVAL;
> }
> }
>
> +static ssize_t adxl372_show_filter_freq_avail(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct adxl372_state *st = iio_priv(indio_dev);
> + int i;
> + size_t len = 0;
> +
> + for (i = 0; i <= st->odr; i++)
> + len += scnprintf(buf + len, PAGE_SIZE - len,
> + "%d ", adxl372_bw_freq_tbl[i]);
> +
> + buf[len - 1] = '\n';
> +
> + return len;
> +}
> +
> static ssize_t adxl372_get_fifo_enabled(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> @@ -826,9 +857,12 @@ static const struct iio_trigger_ops adxl372_trigger_ops = {
> };
>
> static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("400 800 1600 3200 6400");
> +static IIO_DEVICE_ATTR(in_accel_filter_low_pass_3db_frequency_available,
> + 0444, adxl372_show_filter_freq_avail, NULL, 0);
>
> static struct attribute *adxl372_attributes[] = {
> &iio_const_attr_sampling_frequency_available.dev_attr.attr,
> + &iio_dev_attr_in_accel_filter_low_pass_3db_frequency_available.dev_attr.attr,
> NULL,
> };
>

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