iio: adc: ad7173: refactor ain and vref selection

Move validation of analog inputs and reference voltage selection to
separate functions to reduce the size of the channel config parsing
function and improve readability.
Add defines for the number of analog inputs in a channel.

Signed-off-by: Dumitru Ceclan <dumitru.ceclan@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240607-ad4111-v7-5-97e3855900a0@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: dumitruceclan

drivers/iio/adc/ad7173.c

@@ -60,6 +60,7 @@
 #define AD7173_CH_SETUP_AINPOS_MASK	GENMASK(9, 5)
 #define AD7173_CH_SETUP_AINNEG_MASK	GENMASK(4, 0)
 
+#define AD7173_NO_AINS_PER_CHANNEL	2
 #define AD7173_CH_ADDRESS(pos, neg) \
 	(FIELD_PREP(AD7173_CH_SETUP_AINPOS_MASK, pos) | \
 	 FIELD_PREP(AD7173_CH_SETUP_AINNEG_MASK, neg))
@@ -905,13 +906,48 @@ static int ad7173_register_clk_provider(struct iio_dev *indio_dev)
 					   &st->int_clk_hw);
 }
 
+static int ad7173_validate_voltage_ain_inputs(struct ad7173_state *st,
+					      unsigned int ain0, unsigned int ain1)
+{
+	struct device *dev = &st->sd.spi->dev;
+
+	if (ain0 >= st->info->num_inputs ||
+	    ain1 >= st->info->num_inputs)
+		return dev_err_probe(dev, -EINVAL,
+				     "Input pin number out of range for pair (%d %d).\n",
+				     ain0, ain1);
+
+	return 0;
+}
+
+static int ad7173_validate_reference(struct ad7173_state *st, int ref_sel)
+{
+	struct device *dev = &st->sd.spi->dev;
+	int ret;
+
+	if (ref_sel == AD7173_SETUP_REF_SEL_INT_REF && !st->info->has_int_ref)
+		return dev_err_probe(dev, -EINVAL,
+			"Internal reference is not available on current model.\n");
+
+	if (ref_sel == AD7173_SETUP_REF_SEL_EXT_REF2 && !st->info->has_ref2)
+		return dev_err_probe(dev, -EINVAL,
+			"External reference 2 is not available on current model.\n");
+
+	ret = ad7173_get_ref_voltage_milli(st, ref_sel);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Cannot use reference %u\n",
+				     ref_sel);
+
+	return 0;
+}
+
 static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
 {
 	struct ad7173_channel *chans_st_arr, *chan_st_priv;
 	struct ad7173_state *st = iio_priv(indio_dev);
 	struct device *dev = indio_dev->dev.parent;
 	struct iio_chan_spec *chan_arr, *chan;
-	unsigned int ain[2], chan_index = 0;
+	unsigned int ain[AD7173_NO_AINS_PER_CHANNEL], chan_index = 0;
 	int ref_sel, ret, num_channels;
 
 	num_channels = device_get_child_node_count(dev);
@@ -965,11 +1001,9 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
 		if (ret)
 			return ret;
 
-		if (ain[0] >= st->info->num_inputs ||
-		    ain[1] >= st->info->num_inputs)
-			return dev_err_probe(dev, -EINVAL,
-				"Input pin number out of range for pair (%d %d).\n",
-				ain[0], ain[1]);
+		ret = ad7173_validate_voltage_ain_inputs(st, ain[0], ain[1]);
+		if (ret)
+			return ret;
 
 		ret = fwnode_property_match_property_string(child,
 							    "adi,reference-select",
@@ -980,19 +1014,9 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
 		else
 			ref_sel = ret;
 
-		if (ref_sel == AD7173_SETUP_REF_SEL_INT_REF &&
-		    !st->info->has_int_ref)
-			return dev_err_probe(dev, -EINVAL,
-				"Internal reference is not available on current model.\n");
-
-		if (ref_sel == AD7173_SETUP_REF_SEL_EXT_REF2 && !st->info->has_ref2)
-			return dev_err_probe(dev, -EINVAL,
-				"External reference 2 is not available on current model.\n");
-
-		ret = ad7173_get_ref_voltage_milli(st, ref_sel);
-		if (ret < 0)
-			return dev_err_probe(dev, ret,
-					     "Cannot use reference %u\n", ref_sel);
+		ret = ad7173_validate_reference(st, ref_sel);
+		if (ret)
+			return ret;
 
 		if (ref_sel == AD7173_SETUP_REF_SEL_INT_REF)
 			st->adc_mode |= AD7173_ADC_MODE_REF_EN;