iio: adc: stm32-adc: split channel init into several routines

Split stm32_adc_chan_of_init channel initialization function into
several routines to increase readability and prepare channel
generic binding handling.
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-4-olivier.moysan@foss.st.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stm32-adc.c

@@ -194,6 +194,7 @@ struct stm32_adc_cfg {
  * @smpr_val:		sampling time settings (e.g. smpr1 / smpr2)
  * @cal:		optional calibration data on some devices
  * @chan_name:		channel name array
+ * @num_diff:		number of differential channels
  */
 struct stm32_adc {
 	struct stm32_adc_common	*common;
@@ -217,6 +218,7 @@ struct stm32_adc {
 	u32			smpr_val[2];
 	struct stm32_adc_calib	cal;
 	char			chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
+	u32			num_diff;
 };
 
 struct stm32_adc_diff_channel {
@@ -1706,17 +1708,11 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
 	}
 }
 
-static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
+static int stm32_adc_get_legacy_chan_count(struct iio_dev *indio_dev, struct stm32_adc *adc)
 {
 	struct device_node *node = indio_dev->dev.of_node;
-	struct stm32_adc *adc = iio_priv(indio_dev);
 	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
-	struct stm32_adc_diff_channel diff[STM32_ADC_CH_MAX];
-	struct property *prop;
-	const __be32 *cur;
-	struct iio_chan_spec *channels;
-	int scan_index = 0, num_channels = 0, num_diff = 0, ret, i;
-	u32 val, smp = 0;
+	int num_channels = 0, ret;
 
 	ret = of_property_count_u32_elems(node, "st,adc-channels");
 	if (ret > adc_info->max_channels) {
@@ -1727,41 +1723,54 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 	}
 
 	ret = of_property_count_elems_of_size(node, "st,adc-diff-channels",
-					      sizeof(*diff));
+					      sizeof(struct stm32_adc_diff_channel));
 	if (ret > adc_info->max_channels) {
 		dev_err(&indio_dev->dev, "Bad st,adc-diff-channels?\n");
 		return -EINVAL;
 	} else if (ret > 0) {
-		int size = ret * sizeof(*diff) / sizeof(u32);
-
-		num_diff = ret;
+		adc->num_diff = ret;
 		num_channels += ret;
+	}
+
+	return num_channels;
+}
+
+static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
+				      struct stm32_adc *adc,
+				      struct iio_chan_spec *channels)
+{
+	struct device_node *node = indio_dev->dev.of_node;
+	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+	struct stm32_adc_diff_channel diff[STM32_ADC_CH_MAX];
+	u32 num_diff = adc->num_diff;
+	int size = num_diff * sizeof(*diff) / sizeof(u32);
+	int scan_index = 0, val, ret, i;
+	struct property *prop;
+	const __be32 *cur;
+
+	if (num_diff) {
 		ret = of_property_read_u32_array(node, "st,adc-diff-channels",
 						 (u32 *)diff, size);
-		if (ret)
+		if (ret) {
+			dev_err(&indio_dev->dev, "Failed to get diff channels %d\n", ret);
 			return ret;
-	}
+		}
 
-	if (!num_channels) {
-		dev_err(&indio_dev->dev, "No channels configured\n");
-		return -ENODATA;
-	}
+		for (i = 0; i < num_diff; i++) {
+			if (diff[i].vinp >= adc_info->max_channels ||
+			    diff[i].vinn >= adc_info->max_channels) {
+				dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
+					diff[i].vinp, diff[i].vinn);
+				return -EINVAL;
+			}
 
-	/* Optional sample time is provided either for each, or all channels */
-	ret = of_property_count_u32_elems(node, "st,min-sample-time-nsecs");
-	if (ret > 1 && ret != num_channels) {
-		dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs\n");
-		return -EINVAL;
+			stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
+						diff[i].vinp, diff[i].vinn,
+						scan_index, true);
+			scan_index++;
+		}
 	}
 
-	if (timestamping)
-		num_channels++;
-
-	channels = devm_kcalloc(&indio_dev->dev, num_channels,
-				sizeof(struct iio_chan_spec), GFP_KERNEL);
-	if (!channels)
-		return -ENOMEM;
-
 	of_property_for_each_u32(node, "st,adc-channels", prop, cur, val) {
 		if (val >= adc_info->max_channels) {
 			dev_err(&indio_dev->dev, "Invalid channel %d\n", val);
@@ -1771,8 +1780,7 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		/* Channel can't be configured both as single-ended & diff */
 		for (i = 0; i < num_diff; i++) {
 			if (val == diff[i].vinp) {
-				dev_err(&indio_dev->dev,
-					"channel %d miss-configured\n",	val);
+				dev_err(&indio_dev->dev, "channel %d misconfigured\n",	val);
 				return -EINVAL;
 			}
 		}
@@ -1781,19 +1789,54 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		scan_index++;
 	}
 
-	for (i = 0; i < num_diff; i++) {
-		if (diff[i].vinp >= adc_info->max_channels ||
-		    diff[i].vinn >= adc_info->max_channels) {
-			dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
-				diff[i].vinp, diff[i].vinn);
-			return -EINVAL;
-		}
-		stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
-					diff[i].vinp, diff[i].vinn, scan_index,
-					true);
-		scan_index++;
+	return scan_index;
+}
+
+static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
+{
+	struct device_node *node = indio_dev->dev.of_node;
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+	struct iio_chan_spec *channels;
+	int scan_index = 0, num_channels = 0, ret, i;
+	u32 smp = 0;
+
+	ret = stm32_adc_get_legacy_chan_count(indio_dev, adc);
+	if (ret < 0)
+		return ret;
+	num_channels = ret;
+
+	if (!num_channels) {
+		dev_err(&indio_dev->dev, "No channels configured\n");
+		return -ENODATA;
 	}
 
+	if (num_channels > adc_info->max_channels) {
+		dev_err(&indio_dev->dev, "Channel number [%d] exceeds %d\n",
+			num_channels, adc_info->max_channels);
+		return -EINVAL;
+	}
+
+	/* Optional sample time is provided either for each, or all channels */
+	ret = of_property_count_u32_elems(node, "st,min-sample-time-nsecs");
+	if (ret > 1 && ret != num_channels) {
+		dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs\n");
+		return -EINVAL;
+	}
+
+	if (timestamping)
+		num_channels++;
+
+	channels = devm_kcalloc(&indio_dev->dev, num_channels,
+				sizeof(struct iio_chan_spec), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels);
+	if (ret < 0)
+		return ret;
+	scan_index = ret;
+
 	for (i = 0; i < scan_index; i++) {
 		/*
 		 * Using of_property_read_u32_index(), smp value will only be