| Message ID | 2aa347a97e7ea974951609b0bdf81cad0b21b993.1741268122.git.Jonathan.Santos@analog.com |
|---|---|
| State | New |
| Headers | show |
| Series | iio: adc: ad7768-1: Add features, improvements, and fixes | expand |
Looks good. Minor comment inline. On 03/06, 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> > --- Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com> > v4 Changes: > * None > > v3 Changes: > * None > > v2 Changes: > * New patch in v2. > --- > drivers/iio/adc/ad7768-1.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c > index 664d0b535340..9ba00e9089bd 100644 > --- a/drivers/iio/adc/ad7768-1.c > +++ b/drivers/iio/adc/ad7768-1.c > @@ -150,6 +150,17 @@ 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[] = { > + [AD7768_FILTER_SINC5] = 204, > + [AD7768_FILTER_SINC3] = 261, > + [AD7768_FILTER_SINC3_REJ60] = 261, Are these constants from ADAQ7768-1 datasheet? There it says "the sinc3 filter has a −3 dB bandwidth of 0.2617 × ODR." If so, maybe use 262 as SINC3 multiplier? > + [AD7768_FILTER_WIDEBAND] = 433, > +}; > + > static const int ad7768_mclk_div_rates[4] = { > 16, 8, 4, 2, > }; > @@ -228,7 +239,8 @@ static const struct iio_chan_spec ad7768_channels[] = { > .type = IIO_VOLTAGE, > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), > .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | > - BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), > + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | > + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY), > .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), > .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), > .info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ), > @@ -762,7 +774,7 @@ 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)) > @@ -802,6 +814,12 @@ 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; > } > > -- > 2.34.1 >
diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c index 664d0b535340..9ba00e9089bd 100644 --- a/drivers/iio/adc/ad7768-1.c +++ b/drivers/iio/adc/ad7768-1.c @@ -150,6 +150,17 @@ 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[] = { + [AD7768_FILTER_SINC5] = 204, + [AD7768_FILTER_SINC3] = 261, + [AD7768_FILTER_SINC3_REJ60] = 261, + [AD7768_FILTER_WIDEBAND] = 433, +}; + static const int ad7768_mclk_div_rates[4] = { 16, 8, 4, 2, }; @@ -228,7 +239,8 @@ static const struct iio_chan_spec ad7768_channels[] = { .type = IIO_VOLTAGE, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | - BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) | + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY), .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), .info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ), @@ -762,7 +774,7 @@ 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)) @@ -802,6 +814,12 @@ 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> --- v4 Changes: * None v3 Changes: * None v2 Changes: * New patch in v2. --- drivers/iio/adc/ad7768-1.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)