[PATCH v2 3/7] iio: adc: ti-ads1262: Add channel filter support

[Kurt Borja <kuurtb@gmail.com>]

Expose per-channel filter configuration through the filter_type
attribute.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 drivers/iio/adc/ti-ads1262.c | 65 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ti-ads1262.c b/drivers/iio/adc/ti-ads1262.c
index 6103cf5a2d1624a9..ece97a0c2b1304ad 100644
--- a/drivers/iio/adc/ti-ads1262.c
+++ b/drivers/iio/adc/ti-ads1262.c
@@ -146,6 +146,14 @@ enum {
 	ADS1262_RUNMODE_PULSE,
 };
 
+enum {
+	ADS1262_FILTER_SINC1,
+	ADS1262_FILTER_SINC2,
+	ADS1262_FILTER_SINC3,
+	ADS1262_FILTER_SINC4,
+	ADS1262_FILTER_FIR,
+};
+
 enum {
 	ADS1262_DR_2_5_SPS,
 	ADS1262_DR_5_SPS,
@@ -201,6 +209,7 @@ struct ads1262_chip_info {
 
 struct ads1262_channel {
 	u8 input[2];
+	u8 filter;
 	u8 gain;
 	u8 data_rate;
 	u8 reference[3];
@@ -441,7 +450,7 @@ static int ads1262_dev_read_by_cmd(struct ads1262 *st, u8 cmd, __be32 *val)
 static int ads1262_channel_enable(struct ads1262 *st,
 				  struct ads1262_channel *chan)
 {
-	u8 mode0, mode2, inpmux, refmux;
+	u8 mode0, mode1, mode2, inpmux, refmux;
 	int ret;
 
 	/* Avoid using guard() here to mitigate AB/BA deadlock warning */
@@ -449,6 +458,7 @@ static int ads1262_channel_enable(struct ads1262 *st,
 	mode0 = FIELD_PREP(ADS1262_MODE0_INPUT_CHOP_MASK, chan->input_chop) |
 		FIELD_PREP(ADS1262_MODE0_IDAC_CHOP_MASK, chan->idac_chop) |
 		FIELD_PREP(ADS1262_MODE0_REFREV_MASK, chan->ref_reversal);
+	mode1 = FIELD_PREP(ADS1262_MODE1_FILTER_MASK, chan->filter);
 	mode2 = FIELD_PREP(ADS1262_MODE2_DR_MASK, chan->data_rate) |
 		FIELD_PREP(ADS1262_MODE2_GAIN_MASK, chan->gain) |
 		FIELD_PREP(ADS1262_MODE2_BYPASS_MASK, chan->pga_bypass);
@@ -465,6 +475,11 @@ static int ads1262_channel_enable(struct ads1262 *st,
 	if (ret)
 		return ret;
 
+	ret = regmap_update_bits(st->regmap, ADS1262_MODE1_REG,
+				 ADS1262_MODE1_FILTER_MASK, mode1);
+	if (ret)
+		return ret;
+
 	ret = regmap_update_bits(st->regmap, ADS1262_MODE2_REG,
 				 ADS1262_MODE2_DR_MASK |
 				 ADS1262_MODE2_GAIN_MASK |
@@ -682,6 +697,52 @@ static irqreturn_t ads1262_irq_handler(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static int ads1262_get_filter_type(struct iio_dev *indio_dev,
+				   const struct iio_chan_spec *chan)
+{
+	struct ads1262 *st = iio_priv(indio_dev);
+	struct ads1262_channel *chan_data;
+
+	guard(mutex)(&st->chan_lock);
+
+	chan_data = &st->channels[chan->scan_index];
+	return chan_data->filter;
+}
+
+static int ads1262_set_filter_type(struct iio_dev *indio_dev,
+				   const struct iio_chan_spec *chan,
+				   unsigned int val)
+{
+	struct ads1262 *st = iio_priv(indio_dev);
+
+	guard(mutex)(&st->chan_lock);
+	st->channels[chan->scan_index].filter = val;
+
+	return 0;
+}
+
+static const char * const ads1262_filter_type_labels[] = {
+	[ADS1262_FILTER_SINC1] = "sinc1",
+	[ADS1262_FILTER_SINC2] = "sinc2",
+	[ADS1262_FILTER_SINC3] = "sinc3",
+	[ADS1262_FILTER_SINC4] = "sinc4",
+	[ADS1262_FILTER_FIR] = "fir",
+};
+
+static const struct iio_enum ads1262_filter_type_enum = {
+	.items = ads1262_filter_type_labels,
+	.num_items = ARRAY_SIZE(ads1262_filter_type_labels),
+	.get = ads1262_get_filter_type,
+	.set = ads1262_set_filter_type,
+};
+
+static const struct iio_chan_spec_ext_info ads1262_ext_info[] = {
+	IIO_ENUM("filter_type", IIO_SEPARATE, &ads1262_filter_type_enum),
+	IIO_ENUM_AVAILABLE("filter_type", IIO_SHARED_BY_TYPE,
+			   &ads1262_filter_type_enum),
+	{ }
+};
+
 static int ads1262_alloc_channels(struct ads1262 *st,
 				  struct iio_chan_spec **channels)
 {
@@ -718,6 +779,7 @@ static int ads1262_alloc_channels(struct ads1262 *st,
 				BIT(IIO_CHAN_INFO_SAMP_FREQ),
 			.indexed = true,
 			.differential = true,
+			.ext_info = ads1262_ext_info,
 		};
 	}
 
@@ -983,6 +1045,7 @@ static int ads1262_parse_channel_node(struct ads1262 *st,
 	int ret;
 
 	/* Write non-zero default configuration values */
+	chan->filter = ADS1262_FILTER_FIR;
 	chan->data_rate = ADS1262_DR_20_SPS;
 
 	ret = fwnode_property_read_u32_array(node, "diff-channels", pins, ARRAY_SIZE(pins));

-- 
2.54.0