iio: adc: ad7173: refactor channel configuration parsing

Move configurations regarding number of channels from
*_fw_parse_device_config to *_fw_parse_channel_config.
Suggested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/all/20240303162148.3ad91aa2@jic23-huawei/Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Dumitru Ceclan <dumitru.ceclan@analog.com>
Link: https://patch.msgid.link/20240607-ad4111-v7-4-97e3855900a0@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7173.c

@@ -912,7 +912,23 @@ static int ad7173_fw_parse_channel_config(struct iio_dev *indio_dev)
 	struct device *dev = indio_dev->dev.parent;
 	struct iio_chan_spec *chan_arr, *chan;
 	unsigned int ain[2], chan_index = 0;
-	int ref_sel, ret;
+	int ref_sel, ret, num_channels;
+
+	num_channels = device_get_child_node_count(dev);
+
+	if (st->info->has_temp)
+		num_channels++;
+
+	if (num_channels == 0)
+		return dev_err_probe(dev, -ENODATA, "No channels specified\n");
+
+	if (num_channels > st->info->num_channels)
+		return dev_err_probe(dev, -EINVAL,
+			"Too many channels specified. Maximum is %d, not including temperature channel if supported.\n",
+			st->info->num_channels);
+
+	indio_dev->num_channels = num_channels;
+	st->num_channels = num_channels;
 
 	chan_arr = devm_kcalloc(dev, sizeof(*indio_dev->channels),
 				st->num_channels, GFP_KERNEL);
@@ -1007,7 +1023,6 @@ static int ad7173_fw_parse_device_config(struct iio_dev *indio_dev)
 {
 	struct ad7173_state *st = iio_priv(indio_dev);
 	struct device *dev = indio_dev->dev.parent;
-	unsigned int num_channels;
 	int ret;
 
 	st->regulators[0].supply = ad7173_ref_sel_str[AD7173_SETUP_REF_SEL_EXT_REF];
@@ -1066,16 +1081,6 @@ static int ad7173_fw_parse_device_config(struct iio_dev *indio_dev)
 
 	ad7173_sigma_delta_info.irq_line = ret;
 
-	num_channels = device_get_child_node_count(dev);
-
-	if (st->info->has_temp)
-		num_channels++;
-
-	if (num_channels == 0)
-		return dev_err_probe(dev, -ENODATA, "No channels specified\n");
-	indio_dev->num_channels = num_channels;
-	st->num_channels = num_channels;
-
 	return ad7173_fw_parse_channel_config(indio_dev);
 }