[PATCH v2 2/3] iio: adc: ad7192: Improve f_order computation

From: alisadariana
Date: Tue Sep 19 2023 - 20:34:34 EST


From: Alisa-Dariana Roman <alisadariana@xxxxxxxxx>

Instead of using the f_order member of ad7192_state, a function that
computes the f_order coefficient makes more sense. This coefficient is a
function of the sinc filter and chop filter states.

Remove f_order member of ad7192_state structure. Instead use
ad7192_compute_f_order function to compute the f_order coefficient
according to the sinc filter and chop filter states passed as
parameters.

Add ad7192_get_f_order function that returns the current f_order
coefficient of the device.

Add ad7192_compute_f_adc function that computes the f_adc value
according to the sinc filter and chop filter states passed as
parameters.

Add ad7192_get_f_adc function that returns the current f_adc value of
the device.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@xxxxxxxxxx>
---
drivers/iio/adc/ad7192.c | 62 +++++++++++++++++++++++++++++-----------
1 file changed, 46 insertions(+), 16 deletions(-)

diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
index 64bc09ce3cb1..eed3de02c26d 100644
--- a/drivers/iio/adc/ad7192.c
+++ b/drivers/iio/adc/ad7192.c
@@ -179,7 +179,6 @@ struct ad7192_state {
struct clk *mclk;
u16 int_vref_mv;
u32 fclk;
- u32 f_order;
u32 mode;
u32 conf;
u32 scale_avail[8][2];
@@ -419,7 +418,6 @@ static int ad7192_setup(struct iio_dev *indio_dev, struct device_node *np)
st->conf |= AD7192_CONF_REFSEL;

st->conf &= ~AD7192_CONF_CHOP;
- st->f_order = AD7192_NO_SYNC_FILTER;

buf_en = of_property_read_bool(np, "adi,buffer-enable");
if (buf_en)
@@ -530,22 +528,60 @@ static ssize_t ad7192_set(struct device *dev,
return ret ? ret : len;
}

+static int ad7192_compute_f_order(bool sinc3_en, bool chop_en)
+{
+ if (!chop_en)
+ return 1;
+
+ if (sinc3_en)
+ return AD7192_SYNC3_FILTER;
+
+ return AD7192_SYNC4_FILTER;
+}
+
+static int ad7192_get_f_order(struct ad7192_state *st)
+{
+ bool sinc3_en, chop_en;
+
+ sinc3_en = FIELD_GET(AD7192_MODE_SINC3, st->mode);
+ chop_en = FIELD_GET(AD7192_CONF_CHOP, st->conf);
+
+ return ad7192_compute_f_order(sinc3_en, chop_en);
+}
+
+static int ad7192_compute_f_adc(struct ad7192_state *st, bool sinc3_en,
+ bool chop_en)
+{
+ unsigned int f_order = ad7192_compute_f_order(sinc3_en, chop_en);
+
+ return DIV_ROUND_CLOSEST(st->fclk,
+ f_order * FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+}
+
+static int ad7192_get_f_adc(struct ad7192_state *st)
+{
+ unsigned int f_order = ad7192_get_f_order(st);
+
+ return DIV_ROUND_CLOSEST(st->fclk,
+ f_order * FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+}
+
static void ad7192_get_available_filter_freq(struct ad7192_state *st,
int *freq)
{
unsigned int fadc;

/* Formulas for filter at page 25 of the datasheet */
- fadc = DIV_ROUND_CLOSEST(st->fclk,
- AD7192_SYNC4_FILTER * FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+ fadc = ad7192_compute_f_adc(st, false, true);
freq[0] = DIV_ROUND_CLOSEST(fadc * 240, 1024);

- fadc = DIV_ROUND_CLOSEST(st->fclk,
- AD7192_SYNC3_FILTER * FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+ fadc = ad7192_compute_f_adc(st, true, true);
freq[1] = DIV_ROUND_CLOSEST(fadc * 240, 1024);

- fadc = DIV_ROUND_CLOSEST(st->fclk, FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+ fadc = ad7192_compute_f_adc(st, false, false);
freq[2] = DIV_ROUND_CLOSEST(fadc * 230, 1024);
+
+ fadc = ad7192_compute_f_adc(st, true, false);
freq[3] = DIV_ROUND_CLOSEST(fadc * 272, 1024);
}

@@ -628,25 +664,21 @@ static int ad7192_set_3db_filter_freq(struct ad7192_state *st,

switch (idx) {
case 0:
- st->f_order = AD7192_SYNC4_FILTER;
st->mode &= ~AD7192_MODE_SINC3;

st->conf |= AD7192_CONF_CHOP;
break;
case 1:
- st->f_order = AD7192_SYNC3_FILTER;
st->mode |= AD7192_MODE_SINC3;

st->conf |= AD7192_CONF_CHOP;
break;
case 2:
- st->f_order = AD7192_NO_SYNC_FILTER;
st->mode &= ~AD7192_MODE_SINC3;

st->conf &= ~AD7192_CONF_CHOP;
break;
case 3:
- st->f_order = AD7192_NO_SYNC_FILTER;
st->mode |= AD7192_MODE_SINC3;

st->conf &= ~AD7192_CONF_CHOP;
@@ -664,8 +696,7 @@ static int ad7192_get_3db_filter_freq(struct ad7192_state *st)
{
unsigned int fadc;

- fadc = DIV_ROUND_CLOSEST(st->fclk,
- st->f_order * FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+ fadc = ad7192_get_f_adc(st);

if (FIELD_GET(AD7192_CONF_CHOP, st->conf))
return DIV_ROUND_CLOSEST(fadc * 240, 1024);
@@ -713,8 +744,7 @@ static int ad7192_read_raw(struct iio_dev *indio_dev,
*val -= 273 * ad7192_get_temp_scale(unipolar);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SAMP_FREQ:
- *val = st->fclk /
- (st->f_order * 1024 * FIELD_PREP(AD7192_MODE_RATE_MASK, st->mode));
+ *val = DIV_ROUND_CLOSEST(ad7192_get_f_adc(st), 1024);
return IIO_VAL_INT;
case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
*val = ad7192_get_3db_filter_freq(st);
@@ -764,7 +794,7 @@ static int ad7192_write_raw(struct iio_dev *indio_dev,
break;
}

- div = st->fclk / (val * st->f_order * 1024);
+ div = st->fclk / (val * ad7192_get_f_order(st) * 1024);
if (div < 1 || div > 1023) {
ret = -EINVAL;
break;
--
2.34.1