On 5/26/25 5:03 AM, Angelo Dureghello wrote:

From: Angelo Dureghello <adureghello@baylibre.com>

Add gain calibration support, using resistor values set on devicetree,
values to be set accordingly with ADC external RFilter, as explained in
the ad7606c-16 datasheet, rev0, page 37.

Usage example in the fdt yaml documentation.

Tested-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
---

...

+static int ad7606_chan_calib_gain_setup(struct iio_dev *indio_dev)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+	unsigned int num_channels = st->chip_info->num_adc_channels;
+	struct device *dev = st->dev;
+	int ret;
+
+	device_for_each_child_node_scoped(dev, child) {
+		u32 reg, r_gain;
+
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret)
+			return ret;
+
+		/* Chan reg is a 1-based index. */
+		if (reg < 1 || reg > num_channels)
+			return ret;

Shouldn't this return -EINVAL? Otherwise, it will return success for an
out of range reg number and skip any addition child nodes.

+
+		r_gain = 0;
+		ret = fwnode_property_read_u32(child, "adi,rfilter-ohms",
+					       &r_gain);
+		if (r_gain > AD7606_CALIB_GAIN_MAX)
+			return -EINVAL;
+
+		ret = st->bops->reg_write(st, AD7606_CALIB_GAIN(reg - 1),
+			DIV_ROUND_CLOSEST(r_gain, AD7606_CALIB_GAIN_STEP));
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+