diff --git a/drivers/iio/adc/stm32/stm32-adc.c b/drivers/iio/adc/stm32/stm32-adc.c
index 1a13450..9b4b459 100644
--- a/drivers/iio/adc/stm32/stm32-adc.c
+++ b/drivers/iio/adc/stm32/stm32-adc.c
@@ -207,7 +207,11 @@ static int stm32_adc_set_trig(struct iio_dev *indio_dev,
 
 		/* trigger source */
 		extsel = trig_info[ret].extsel;
-		exten = STM32_EXTEN_HWTRIG_RISING_EDGE;
+
+		/* default to rising edge if no polarity */
+		if (adc->exten == STM32_EXTEN_SWTRIG)
+			adc->exten = STM32_EXTEN_HWTRIG_RISING_EDGE;
+		exten = adc->exten;
 	}
 
 	spin_lock_irqsave(&adc->lock, flags);
@@ -221,6 +225,40 @@ static int stm32_adc_set_trig(struct iio_dev *indio_dev,
 	return 0;
 }
 
+static int stm32_adc_set_trig_pol(struct iio_dev *indio_dev,
+				  const struct iio_chan_spec *chan,
+				  unsigned int type)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+
+	adc->exten = type;
+
+	return 0;
+}
+
+static int stm32_adc_get_trig_pol(struct iio_dev *indio_dev,
+				  const struct iio_chan_spec *chan)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+
+	return adc->exten;
+}
+
+static const char * const stm32_trig_pol_items[] = {
+	[STM32_EXTEN_SWTRIG] = "swtrig",
+	[STM32_EXTEN_HWTRIG_RISING_EDGE] = "rising-edge",
+	[STM32_EXTEN_HWTRIG_FALLING_EDGE] = "falling-edge",
+	[STM32_EXTEN_HWTRIG_BOTH_EDGES] = "both-edges",
+};
+
+const struct iio_enum stm32_adc_trig_pol = {
+	.items = stm32_trig_pol_items,
+	.num_items = ARRAY_SIZE(stm32_trig_pol_items),
+	.get = stm32_adc_get_trig_pol,
+	.set = stm32_adc_set_trig_pol,
+};
+EXPORT_SYMBOL_GPL(stm32_adc_trig_pol);
+
 /**
  * stm32_adc_conv_irq_enable() - Unmask end of conversion irq
  * @adc: stm32 adc instance
@@ -893,6 +931,7 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
 	chan->scan_type.realbits = adc->common->data->highres;
 	chan->scan_type.storagebits = STM32_STORAGEBITS;
 	chan->scan_type.shift = 0;
+	chan->ext_info = adc->common->data->ext_info;
 }
 
 static int stm32_adc_chan_of_init(struct iio_dev *indio_dev,
diff --git a/drivers/iio/adc/stm32/stm32-adc.h b/drivers/iio/adc/stm32/stm32-adc.h
index fe3568b..6c9b70d 100644
--- a/drivers/iio/adc/stm32/stm32-adc.h
+++ b/drivers/iio/adc/stm32/stm32-adc.h
@@ -234,6 +234,7 @@ struct stm32_adc_reginfo {
  * @ext_triggers:	Reference to trigger info for regular channels
  * @jext_triggers:	Reference to trigger info for injected channels
  * @adc_reginfo:	stm32 ADC registers description
+ * @ext_info:		Extended channel info
  * @highres:		Max resolution
  * @max_clock_rate:	Max input clock rate
  * @clk_sel:		routine to select common clock and prescaler
@@ -251,6 +252,7 @@ struct stm32_adc_ops {
 	const struct stm32_adc_trig_info *ext_triggers;
 	const struct stm32_adc_trig_info *jext_triggers;
 	const struct stm32_adc_reginfo *adc_reginfo;
+	const struct iio_chan_spec_ext_info *ext_info;
 	int highres;
 	unsigned long max_clock_rate;
 	int (*clk_sel)(struct stm32_adc *adc);
@@ -273,6 +275,7 @@ struct stm32_adc_ops {
  * @id:			ADC instance number (e.g. adc 1, 2 or 3)
  * @offset:		ADC instance register offset in ADC block
  * @max_channels:	Max channels number for this ADC.
+ * @exten:		External trigger config (enable/polarity)
  * @extrig_list:	External trigger list (for regular channel)
  * @completion:		end of single conversion completion
  * @buffer:		data buffer
@@ -295,6 +298,7 @@ struct stm32_adc {
 	int			id;
 	int			offset;
 	int			max_channels;
+	enum stm32_adc_exten	exten;
 	struct list_head	extrig_list;
 	struct completion	completion;
 	u16			*buffer;
diff --git a/drivers/iio/adc/stm32/stm32f4-adc.c b/drivers/iio/adc/stm32/stm32f4-adc.c
index 4d7a2a8..e033a68 100644
--- a/drivers/iio/adc/stm32/stm32f4-adc.c
+++ b/drivers/iio/adc/stm32/stm32f4-adc.c
@@ -555,11 +555,23 @@ static int stm32f4_adc_clk_sel(struct stm32_adc *adc)
 	return 0;
 }
 
+static const struct iio_chan_spec_ext_info stm32f4_adc_ext_info[] = {
+	IIO_ENUM("trigger_pol", IIO_SHARED_BY_ALL, &stm32_adc_trig_pol),
+	{
+		.name = "trigger_pol_available",
+		.shared = IIO_SHARED_BY_ALL,
+		.read = iio_enum_available_read,
+		.private = (uintptr_t)&stm32_adc_trig_pol,
+	},
+	{},
+};
+
 static const struct stm32_adc_ops stm32f4_adc_ops = {
 	.adc_info = stm32f4_adc_info,
 	.ext_triggers = stm32f4_adc_ext_triggers,
 	.jext_triggers = stm32f4_adc_jext_triggers,
 	.adc_reginfo = &stm32f4_adc_reginfo,
+	.ext_info = stm32f4_adc_ext_info,
 	.highres = 12,
 	.max_clock_rate = 36000000,
 	.clk_sel = stm32f4_adc_clk_sel,
