iio: adc: ad4170-4: Add support for calibration bias

Add support for ADC calibration bias/offset configuration.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://patch.msgid.link/f240fce693d62ec8d587885074bf540e01919b31.1751895245.git.marcelo.schmitt@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: machschmitt

drivers/iio/adc/ad4170-4.c

@@ -626,6 +626,7 @@ static const struct iio_chan_spec ad4170_channel_template = {
 	.differential = 1,
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 			      BIT(IIO_CHAN_INFO_SCALE) |
+			      BIT(IIO_CHAN_INFO_CALIBBIAS) |
 			      BIT(IIO_CHAN_INFO_CALIBSCALE) |
 			      BIT(IIO_CHAN_INFO_OFFSET),
 	.info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE),
@@ -949,6 +950,9 @@ static int ad4170_read_raw(struct iio_dev *indio_dev,
 		pga = FIELD_GET(AD4170_AFE_PGA_GAIN_MSK, setup->afe);
 		*val = chan_info->offset_tbl[pga];
 		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		*val = setup->offset;
+		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_CALIBSCALE:
 		*val = setup->gain;
 		return IIO_VAL_INT;
@@ -1066,6 +1070,18 @@ static int ad4170_set_pga(struct ad4170_state *st,
 	return ad4170_write_channel_setup(st, chan->address, false);
 }
 
+static int ad4170_set_calib_offset(struct ad4170_state *st,
+				   struct iio_chan_spec const *chan, int val)
+{
+	struct ad4170_chan_info *chan_info = &st->chan_infos[chan->address];
+	struct ad4170_setup *setup = &chan_info->setup;
+
+	guard(mutex)(&st->lock);
+	setup->offset = val;
+
+	return ad4170_write_channel_setup(st, chan->address, false);
+}
+
 static int ad4170_set_calib_gain(struct ad4170_state *st,
 				 struct iio_chan_spec const *chan, int val)
 {
@@ -1087,6 +1103,8 @@ static int __ad4170_write_raw(struct iio_dev *indio_dev,
 	switch (info) {
 	case IIO_CHAN_INFO_SCALE:
 		return ad4170_set_pga(st, chan, val, val2);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return ad4170_set_calib_offset(st, chan, val);
 	case IIO_CHAN_INFO_CALIBSCALE:
 		return ad4170_set_calib_gain(st, chan, val);
 	default:
@@ -1115,6 +1133,7 @@ static int ad4170_write_raw_get_fmt(struct iio_dev *indio_dev,
 	switch (info) {
 	case IIO_CHAN_INFO_SCALE:
 		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_CALIBBIAS:
 	case IIO_CHAN_INFO_CALIBSCALE:
 		return IIO_VAL_INT;
 	default: