diff options
| author | Jonathan Santos <Jonathan.Santos@analog.com> | 2025-06-11 08:52:03 -0300 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2025-07-13 15:36:24 +0100 |
| commit | 00a468c9312645c61ebe3c272a4cbf3dc2f82187 (patch) | |
| tree | 1fb8dd90478e00043da9533e31a34dae0e1e0acc | |
| parent | 5eef68d672b777e930df0fef1a970e9aacbce343 (diff) | |
iio: adc: ad7768-1: add low pass -3dB cutoff attribute
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.
Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
Link: https://patch.msgid.link/804d66f1858014d7278aec3344d81c223661e878.1749569957.git.Jonathan.Santos@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
| -rw-r--r-- | drivers/iio/adc/ad7768-1.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c index 72a960c7fb4e..a2e061f0cb08 100644 --- a/drivers/iio/adc/ad7768-1.c +++ b/drivers/iio/adc/ad7768-1.c @@ -22,6 +22,7 @@ #include <linux/sysfs.h> #include <linux/spi/spi.h> #include <linux/unaligned.h> +#include <linux/units.h> #include <linux/util_macros.h> #include <linux/iio/buffer.h> @@ -152,6 +153,14 @@ enum ad7768_scan_type { AD7768_SCAN_TYPE_HIGH_SPEED, }; +/* -3dB cutoff frequency multipliers (relative to ODR) for each filter type. */ +static const int ad7768_filter_3db_odr_multiplier[] = { + [AD7768_FILTER_SINC5] = 204, /* 0.204 */ + [AD7768_FILTER_SINC3] = 262, /* 0.2617 */ + [AD7768_FILTER_SINC3_REJ60] = 262, /* 0.2617 */ + [AD7768_FILTER_WIDEBAND] = 433, /* 0.433 */ +}; + static const int ad7768_mclk_div_rates[] = { 16, 8, 4, 2, }; @@ -746,6 +755,7 @@ 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_LOW_PASS_FILTER_3DB_FREQUENCY) | BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), @@ -766,7 +776,7 @@ 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)) @@ -805,6 +815,12 @@ static int ad7768_read_raw(struct iio_dev *indio_dev, *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, MILLI); + + return IIO_VAL_INT; } return -EINVAL; |