Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
iio: adc: ad7124: support fractional sampling_frequency
Modify the attribute read/write functions for sampling_frequency and
filter_low_pass_3db_frequency to return fractional values.
These ADCs support output data rates in the single digits, so being
able to specify fractional values is necessary to use all possible
sampling frequencies.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
authored by
David Lechner
and committed by
Jonathan Cameron
b2dbba2b
d904b8e6
+39
-26
+39
-26
drivers/iio/adc/ad7124.c
+39
-26
drivers/iio/adc/ad7124.c
···
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bool buf_negative;
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unsigned int vref_mv;
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unsigned int pga_bits;
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-
unsigned int odr;
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unsigned int odr_sel_bits;
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unsigned int filter_type;
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unsigned int calibration_offset;
···
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return fclk_hz;
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}
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-
static void ad7124_set_channel_odr(struct ad7124_state *st, unsigned int channel, unsigned int odr)
288
+
static u32 ad7124_get_fadc_divisor(struct ad7124_state *st, unsigned int channel)
289
+
{
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+
/*
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+
* The output data rate (f_ADC) is f_CLK / divisor. We are returning
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+
* the divisor.
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+
*/
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+
return st->channels[channel].cfg.odr_sel_bits * 32 * 4;
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+
}
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+
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+
static void ad7124_set_channel_odr(struct ad7124_state *st, unsigned int channel,
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+
unsigned int odr, unsigned int odr_micro)
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{
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unsigned int fclk, factor, odr_sel_bits;
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···
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* FS[10:0] can have a value from 1 to 2047
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*/
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factor = 32 * 4; /* N = 4 for default sinc4 filter. */
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-
odr_sel_bits = clamp(DIV_ROUND_CLOSEST(fclk, odr * factor), 1, 2047);
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+
odr_sel_bits = DIV_ROUND_CLOSEST(fclk, odr * factor +
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+
odr_micro * factor / MICRO);
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+
odr_sel_bits = clamp(odr_sel_bits, 1, 2047);
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if (odr_sel_bits != st->channels[channel].cfg.odr_sel_bits)
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st->channels[channel].cfg.live = false;
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309
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-
/* fADC = fCLK / (FS[10:0] x 32) */
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-
st->channels[channel].cfg.odr = DIV_ROUND_CLOSEST(fclk, odr_sel_bits *
319
-
factor);
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st->channels[channel].cfg.odr_sel_bits = odr_sel_bits;
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}
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-
static int ad7124_get_3db_filter_freq(struct ad7124_state *st,
324
-
unsigned int channel)
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+
static int ad7124_get_3db_filter_factor(struct ad7124_state *st,
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+
unsigned int channel)
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{
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-
unsigned int fadc;
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-
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-
fadc = st->channels[channel].cfg.odr;
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-
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+
/*
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* 3dB point is the f_CLK rate times some factor. This functions returns
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+
* the factor times 1000.
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+
*/
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switch (st->channels[channel].cfg.filter_type) {
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case AD7124_FILTER_FILTER_SINC3:
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-
return DIV_ROUND_CLOSEST(fadc * 272, 1000);
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+
return 272;
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case AD7124_FILTER_FILTER_SINC4:
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-
return DIV_ROUND_CLOSEST(fadc * 230, 1000);
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+
return 230;
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default:
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return -EINVAL;
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}
···
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bool buf_negative;
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unsigned int vref_mv;
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unsigned int pga_bits;
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-
unsigned int odr;
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unsigned int odr_sel_bits;
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unsigned int filter_type;
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unsigned int calibration_offset;
···
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cfg->buf_negative == cfg_aux->buf_negative &&
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cfg->vref_mv == cfg_aux->vref_mv &&
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cfg->pga_bits == cfg_aux->pga_bits &&
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-
cfg->odr == cfg_aux->odr &&
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cfg->odr_sel_bits == cfg_aux->odr_sel_bits &&
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cfg->filter_type == cfg_aux->filter_type &&
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cfg->calibration_offset == cfg_aux->calibration_offset &&
···
724
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725
719
case IIO_CHAN_INFO_SAMP_FREQ:
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mutex_lock(&st->cfgs_lock);
727
-
*val = st->channels[chan->address].cfg.odr;
721
+
*val = ad7124_get_fclk_hz(st);
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+
*val2 = ad7124_get_fadc_divisor(st, chan->address);
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723
mutex_unlock(&st->cfgs_lock);
729
724
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-
return IIO_VAL_INT;
731
-
case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
732
-
mutex_lock(&st->cfgs_lock);
733
-
*val = ad7124_get_3db_filter_freq(st, chan->scan_index);
734
-
mutex_unlock(&st->cfgs_lock);
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+
return IIO_VAL_FRACTIONAL;
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+
case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY: {
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+
guard(mutex)(&st->cfgs_lock);
735
728
736
-
return IIO_VAL_INT;
729
+
ret = ad7124_get_3db_filter_factor(st, chan->address);
730
+
if (ret < 0)
731
+
return ret;
732
+
733
+
/* 3dB point is the f_CLK rate times a fractional value */
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+
*val = ret * ad7124_get_fclk_hz(st);
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+
*val2 = MILLI * ad7124_get_fadc_divisor(st, chan->address);
736
+
return IIO_VAL_FRACTIONAL;
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+
}
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738
default:
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return -EINVAL;
739
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}
···
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744
758
745
switch (info) {
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746
case IIO_CHAN_INFO_SAMP_FREQ:
760
-
if (val2 != 0 || val == 0)
747
+
if (val2 < 0 || val < 0 || (val2 == 0 && val == 0))
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return -EINVAL;
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749
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-
ad7124_set_channel_odr(st, chan->address, val);
750
+
ad7124_set_channel_odr(st, chan->address, val, val2);
764
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765
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return 0;
766
753
case IIO_CHAN_INFO_SCALE:
···
1309
1296
* regardless of the selected power mode. Round it up to 10 and
1310
1297
* set all channels to this default value.
1311
1298
*/
1312
-
ad7124_set_channel_odr(st, i, 10);
1299
+
ad7124_set_channel_odr(st, i, 10, 0);
1313
1300
}
1314
1301
1315
1302
ad7124_disable_all(&st->sd);