| Message ID | 91b697b66a42ead9e05dd4e79d6fb1e776c569d6.1737985435.git.Jonathan.Santos@analog.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add features, improvements, and fixes | expand |
On 1/27/25 9:14 AM, Jonathan Santos wrote: > Ad7768-1 has a different -3db frequency multiplier depending on > the filter type configured. The cutoff frequency also varies according > to the current ODR. > > Add a readonly low pass -3dB frequency cutoff attribute to clarify to > the user which bandwidth is being allowed depending on the filter > configurations. > > Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com> > --- > v2 Changes: > * New patch in v2. > --- > drivers/iio/adc/ad7768-1.c | 23 +++++++++++++++++++++-- > 1 file changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c > index 6d0b430a8d54..daf91ef6f77b 100644 > --- a/drivers/iio/adc/ad7768-1.c > +++ b/drivers/iio/adc/ad7768-1.c > @@ -149,6 +149,18 @@ enum ad7768_scan_type { > AD7768_SCAN_TYPE_HIGH_SPEED, > }; > > +/* > + * -3dB cutoff frequency multipliers (relative to ODR) for > + * each filter type. Values are multiplied by 1000. > + */ > +static const int ad7768_filter_3db_odr_multiplier[] = { > + [SINC5] = 204, > + [SINC5_DEC_X8] = 204, > + [SINC5_DEC_X16] = 204, > + [SINC3] = 261, > + [WIDEBAND] = 433, > +}; > + > static const int ad7768_mclk_div_rates[4] = { > 16, 8, 4, 2, > }; > @@ -202,7 +214,8 @@ static const struct iio_chan_spec ad7768_channels[] = { > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), > .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) | > - BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), > + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | > + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY), > .ext_info = ad7768_ext_info, > .indexed = 1, > .channel = 0, > @@ -802,7 +815,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev, > { > struct ad7768_state *st = iio_priv(indio_dev); > const struct iio_scan_type *scan_type; > - int scale_uv, ret; > + int scale_uv, ret, temp; > > scan_type = iio_get_current_scan_type(indio_dev, chan); > if (IS_ERR(scan_type)) > @@ -842,6 +855,12 @@ static int ad7768_read_raw(struct iio_dev *indio_dev, > case IIO_CHAN_INFO_OVERSAMPLING_RATIO: > *val = st->oversampling_ratio; > > + return IIO_VAL_INT; > + > + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY: > + temp = st->samp_freq * ad7768_filter_3db_odr_multiplier[st->filter_type]; > + *val = DIV_ROUND_CLOSEST(temp, 1000); > + > return IIO_VAL_INT; > } > If this is read-only, do we actually need it? It looks like the attribute is going to return 1 of 3 values that exactly matches the filter_type attribute, so this is not really giving any additional info.
diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c index 6d0b430a8d54..daf91ef6f77b 100644 --- a/drivers/iio/adc/ad7768-1.c +++ b/drivers/iio/adc/ad7768-1.c @@ -149,6 +149,18 @@ enum ad7768_scan_type { AD7768_SCAN_TYPE_HIGH_SPEED, }; +/* + * -3dB cutoff frequency multipliers (relative to ODR) for + * each filter type. Values are multiplied by 1000. + */ +static const int ad7768_filter_3db_odr_multiplier[] = { + [SINC5] = 204, + [SINC5_DEC_X8] = 204, + [SINC5_DEC_X16] = 204, + [SINC3] = 261, + [WIDEBAND] = 433, +}; + static const int ad7768_mclk_div_rates[4] = { 16, 8, 4, 2, }; @@ -202,7 +214,8 @@ static const struct iio_chan_spec ad7768_channels[] = { .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) | - BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY), .ext_info = ad7768_ext_info, .indexed = 1, .channel = 0, @@ -802,7 +815,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev, { struct ad7768_state *st = iio_priv(indio_dev); const struct iio_scan_type *scan_type; - int scale_uv, ret; + int scale_uv, ret, temp; scan_type = iio_get_current_scan_type(indio_dev, chan); if (IS_ERR(scan_type)) @@ -842,6 +855,12 @@ static int ad7768_read_raw(struct iio_dev *indio_dev, case IIO_CHAN_INFO_OVERSAMPLING_RATIO: *val = st->oversampling_ratio; + return IIO_VAL_INT; + + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY: + temp = st->samp_freq * ad7768_filter_3db_odr_multiplier[st->filter_type]; + *val = DIV_ROUND_CLOSEST(temp, 1000); + return IIO_VAL_INT; }
Ad7768-1 has a different -3db frequency multiplier depending on the filter type configured. The cutoff frequency also varies according to the current ODR. Add a readonly low pass -3dB frequency cutoff attribute to clarify to the user which bandwidth is being allowed depending on the filter configurations. Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com> --- v2 Changes: * New patch in v2. --- drivers/iio/adc/ad7768-1.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-)