diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c
index ac0ffff6c5ae..1c49eed298d8 100644
--- a/drivers/iio/adc/ad7949.c
+++ b/drivers/iio/adc/ad7949.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/regulator/consumer.h>
 #include <linux/spi/spi.h>
+#include <linux/of.h>
 
 #define AD7949_MASK_CHANNEL_SEL		GENMASK(9, 7)
 #define AD7949_MASK_TOTAL		GENMASK(13, 0)
@@ -24,6 +25,18 @@ enum {
 	ID_AD7689,
 };
 
+enum ad7949_ref_sel {
+	AD7949_REF_2V5 = 0, /* 2.5V internal ref + temp sensor */
+	AD7949_REF_4V0, /* 4.096V internal ref + temp sensor */
+	AD7949_REF_EXT_TEMP, /* External ref + temp sensor, no buffer */
+	AD7949_REF_EXT_TEMP_BUF, /* External ref + temp sensor + buffer */
+	AD7949_REF_RSRV_4,
+	AD7949_REF_RSRV_5,
+	AD7949_REF_EXT, /* External ref, no temp, no buffer */
+	AD7949_REF_EXT_BUF, /* External ref + buffer, no temp */
+	AD7949_REF_MAX,
+};
+
 struct ad7949_adc_spec {
 	u8 num_channels;
 	u8 resolution;
@@ -41,6 +54,7 @@ struct ad7949_adc_spec {
  * @vref: regulator generating Vref
  * @iio_dev: reference to iio structure
  * @spi: reference to spi structure
+ * @ref_sel: selected reference voltage source
  * @resolution: resolution of the chip
  * @cfg: copy of the configuration register
  * @current_channel: current channel in use
@@ -51,6 +65,7 @@ struct ad7949_adc_chip {
 	struct regulator *vref;
 	struct iio_dev *indio_dev;
 	struct spi_device *spi;
+	enum ad7949_ref_sel ref_sel;
 	u8 resolution;
 	u16 cfg;
 	unsigned int current_channel;
@@ -187,11 +202,20 @@ static int ad7949_spi_read_raw(struct iio_dev *indio_dev,
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_SCALE:
-		ret = regulator_get_voltage(ad7949_adc->vref);
-		if (ret < 0)
-			return ret;
+		if (ad7949_adc->vref) {
+			ret = regulator_get_voltage(ad7949_adc->vref);
+			if (ret < 0)
+				return ret;
+
+			*val = ret / 5000;
+		} else if (ad7949_adc->ref_sel == AD7949_REF_2V5) {
+			*val = 2500;
+		} else if (ad7949_adc->ref_sel == AD7949_REF_4V0) {
+			*val = 4096;
+		} else {
+			return -EINVAL;
+		}
 
-		*val = ret / 5000;
 		return IIO_VAL_INT;
 	}
 
@@ -223,10 +247,18 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc)
 {
 	int ret;
 	int val;
+	u16 adc_config = 0;
 
-	/* Sequencer disabled, CFG readback disabled, IN0 as default channel */
 	ad7949_adc->current_channel = 0;
-	ret = ad7949_spi_write_cfg(ad7949_adc, 0x3C79, AD7949_MASK_TOTAL);
+	ad7949_adc->cfg = 0;
+
+	adc_config = (0x3c << 8);
+	adc_config |= ((ad7949_adc->current_channel & 0x07) << 7);
+	adc_config |= (1 << 6);
+	adc_config |= (ad7949_adc->ref_sel << 3);
+	adc_config |= 1;
+
+	ret = ad7949_spi_write_cfg(ad7949_adc, adc_config, AD7949_MASK_TOTAL);
 
 	/*
 	 * Do two dummy conversions to apply the first configuration setting.
@@ -245,6 +277,7 @@ static int ad7949_spi_probe(struct spi_device *spi)
 	struct ad7949_adc_chip *ad7949_adc;
 	struct iio_dev *indio_dev;
 	int ret;
+	u32 temp;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*ad7949_adc));
 	if (!indio_dev) {
@@ -263,21 +296,34 @@ static int ad7949_spi_probe(struct spi_device *spi)
 	ad7949_adc = iio_priv(indio_dev);
 	ad7949_adc->indio_dev = indio_dev;
 	ad7949_adc->spi = spi;
+	ad7949_adc->vref = NULL;
 
 	spec = &ad7949_adc_spec[spi_get_device_id(spi)->driver_data];
 	indio_dev->num_channels = spec->num_channels;
 	ad7949_adc->resolution = spec->resolution;
 
-	ad7949_adc->vref = devm_regulator_get(dev, "vref");
-	if (IS_ERR(ad7949_adc->vref)) {
-		dev_err(dev, "fail to request regulator\n");
-		return PTR_ERR(ad7949_adc->vref);
-	}
-
-	ret = regulator_enable(ad7949_adc->vref);
-	if (ret < 0) {
-		dev_err(dev, "fail to enable regulator\n");
-		return ret;
+	ret = of_property_read_u32(ad7949_adc->indio_dev->dev.of_node,
+			"adi,reference-select",
+			&temp);
+	if ((ret == 0) && (temp < AD7949_REF_MAX))
+		ad7949_adc->ref_sel = (enum ad7949_ref_sel)temp;
+	else
+		ad7949_adc->ref_sel = AD7949_REF_EXT_BUF;
+
+	/* Check whether using external Vref */
+	if ((ad7949_adc->ref_sel != AD7949_REF_2V5) &&
+			(ad7949_adc->ref_sel != AD7949_REF_4V0)) {
+		ad7949_adc->vref = devm_regulator_get(dev, "vref");
+		if (IS_ERR(ad7949_adc->vref)) {
+			dev_err(dev, "fail to request regulator\n");
+			return PTR_ERR(ad7949_adc->vref);
+		}
+
+		ret = regulator_enable(ad7949_adc->vref);
+		if (ret < 0) {
+			dev_err(dev, "fail to enable regulator\n");
+			return ret;
+		}
 	}
 
 	mutex_init(&ad7949_adc->lock);
@@ -298,7 +344,8 @@ static int ad7949_spi_probe(struct spi_device *spi)
 
 err:
 	mutex_destroy(&ad7949_adc->lock);
-	regulator_disable(ad7949_adc->vref);
+	if (ad7949_adc->vref)
+		regulator_disable(ad7949_adc->vref);
 
 	return ret;
 }
@@ -310,7 +357,8 @@ static int ad7949_spi_remove(struct spi_device *spi)
 
 	iio_device_unregister(indio_dev);
 	mutex_destroy(&ad7949_adc->lock);
-	regulator_disable(ad7949_adc->vref);
+	if (ad7949_adc->vref)
+		regulator_disable(ad7949_adc->vref);
 
 	return 0;
 }
