iio: adc: aspeed: Add vref config function

Add the function to check the vref_fixed_mv and set the value to driver
data.
Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Link: https://lore.kernel.org/r/20210922081520.30580-4-billy_tsai@aspeedtech.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/aspeed_adc.c

@@ -130,7 +130,7 @@ static int aspeed_adc_read_raw(struct iio_dev *indio_dev,
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_SCALE:
-		*val = data->model_data->vref_fixed_mv;
+		*val = data->vref_mv;
 		*val2 = ASPEED_RESOLUTION_BITS;
 		return IIO_VAL_FRACTIONAL_LOG2;
 
@@ -195,6 +195,17 @@ static const struct iio_info aspeed_adc_iio_info = {
 	.debugfs_reg_access = aspeed_adc_reg_access,
 };
 
+static int aspeed_adc_vref_config(struct iio_dev *indio_dev)
+{
+	struct aspeed_adc_data *data = iio_priv(indio_dev);
+
+	if (data->model_data->vref_fixed_mv) {
+		data->vref_mv = data->model_data->vref_fixed_mv;
+		return 0;
+	}
+	return 0;
+}
+
 static int aspeed_adc_probe(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev;
@@ -249,6 +260,10 @@ static int aspeed_adc_probe(struct platform_device *pdev)
 	}
 	reset_control_deassert(data->rst);
 
+	ret = aspeed_adc_vref_config(indio_dev);
+	if (ret)
+		goto vref_config_error;
+
 	if (data->model_data->wait_init_sequence) {
 		/* Enable engine in normal mode. */
 		writel(FIELD_PREP(ASPEED_ADC_OP_MODE,
@@ -297,6 +312,7 @@ static int aspeed_adc_probe(struct platform_device *pdev)
 	clk_disable_unprepare(data->clk_scaler->clk);
 clk_enable_error:
 poll_timeout_error:
+vref_config_error:
 	reset_control_assert(data->rst);
 reset_error:
 	clk_hw_unregister_divider(data->clk_scaler);