Commit cef27609 authored by Alexandru Tachici's avatar Alexandru Tachici Committed by Jonathan Cameron
Browse files

iio: adc: ad7124: add 3db filter 



This patch adds the LOW_PASS_FILTER_3DB_FREQUENCY attribute
in iio_chan_spec for each channel. The used filters are sinc3
or sinc4. The filter type with the highest output data rate
is used when setting a low pass frequency in the channel's sysfs.

Signed-off-by: default avatarAlexandru Tachici <alexandru.tachici@analog.com>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent ebf7a112

drivers/iio/adc/ad7124.c

+68 −1
Original line number Diff line number Diff line
@@ -70,6 +70,11 @@ 
/* AD7124_FILTER_X */

#define AD7124_FILTER_FS_MSK		GENMASK(10, 0)

#define AD7124_FILTER_FS(x)		FIELD_PREP(AD7124_FILTER_FS_MSK, x)

#define AD7124_FILTER_TYPE_MSK		GENMASK(23, 21)

#define AD7124_FILTER_TYPE_SEL(x)	FIELD_PREP(AD7124_FILTER_TYPE_MSK, x)



#define AD7124_SINC3_FILTER 2

#define AD7124_SINC4_FILTER 0



enum ad7124_ids {

	ID_AD7124_4,
@@ -119,6 +124,7 @@ struct ad7124_channel_config { 
	unsigned int vref_mv;

	unsigned int pga_bits;

	unsigned int odr;

	unsigned int filter_type;

};



struct ad7124_state {
@@ -138,7 +144,8 @@ static const struct iio_chan_spec ad7124_channel_template = { 
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |

		BIT(IIO_CHAN_INFO_SCALE) |

		BIT(IIO_CHAN_INFO_OFFSET) |

		BIT(IIO_CHAN_INFO_SAMP_FREQ),

		BIT(IIO_CHAN_INFO_SAMP_FREQ) |

		BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),

	.scan_type = {

		.sign = 'u',

		.realbits = 24,
@@ -281,6 +288,58 @@ static int ad7124_set_channel_gain(struct ad7124_state *st, 
	return 0;

}



static int ad7124_get_3db_filter_freq(struct ad7124_state *st,

				      unsigned int channel)

{

	unsigned int fadc;



	fadc = st->channel_config[channel].odr;



	switch (st->channel_config[channel].filter_type) {

	case AD7124_SINC3_FILTER:

		return DIV_ROUND_CLOSEST(fadc * 230, 1000);

	case AD7124_SINC4_FILTER:

		return DIV_ROUND_CLOSEST(fadc * 262, 1000);

	default:

		return -EINVAL;

	}

}



static int ad7124_set_3db_filter_freq(struct ad7124_state *st,

				      unsigned int channel,

				      unsigned int freq)

{

	unsigned int sinc4_3db_odr;

	unsigned int sinc3_3db_odr;

	unsigned int new_filter;

	unsigned int new_odr;



	sinc4_3db_odr = DIV_ROUND_CLOSEST(freq * 1000, 230);

	sinc3_3db_odr = DIV_ROUND_CLOSEST(freq * 1000, 262);



	if (sinc4_3db_odr > sinc3_3db_odr) {

		new_filter = AD7124_SINC3_FILTER;

		new_odr = sinc4_3db_odr;

	} else {

		new_filter = AD7124_SINC4_FILTER;

		new_odr = sinc3_3db_odr;

	}



	if (st->channel_config[channel].filter_type != new_filter) {

		int ret;



		st->channel_config[channel].filter_type = new_filter;

		ret = ad7124_spi_write_mask(st, AD7124_FILTER(channel),

					    AD7124_FILTER_TYPE_MSK,

					    AD7124_FILTER_TYPE_SEL(new_filter),

					    3);

		if (ret < 0)

			return ret;

	}



	return ad7124_set_channel_odr(st, channel, new_odr);

}



static int ad7124_read_raw(struct iio_dev *indio_dev,

			   struct iio_chan_spec const *chan,

			   int *val, int *val2, long info)
@@ -322,6 +381,9 @@ static int ad7124_read_raw(struct iio_dev *indio_dev, 
	case IIO_CHAN_INFO_SAMP_FREQ:

		*val = st->channel_config[chan->address].odr;



		return IIO_VAL_INT;

	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:

		*val = ad7124_get_3db_filter_freq(st, chan->scan_index);

		return IIO_VAL_INT;

	default:

		return -EINVAL;
@@ -355,6 +417,11 @@ static int ad7124_write_raw(struct iio_dev *indio_dev, 
		gain = DIV_ROUND_CLOSEST(res, val2);



		return ad7124_set_channel_gain(st, chan->address, gain);

	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:

		if (val2 != 0)

			return -EINVAL;



		return ad7124_set_3db_filter_freq(st, chan->address, val);

	default:

		return -EINVAL;

	}

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