1 files changed, 609 insertions, 24 deletions

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 5715e79f4935..9b49a6addc2a 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -21,7 +21,14 @@
 
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
 #include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/timer/stm32-timer-trigger.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
@@ -58,21 +65,71 @@
 
 /* STM32F4_ADC_CR2 - bit fields */
 #define STM32F4_SWSTART			BIT(30)
+#define STM32F4_EXTEN_SHIFT		28
 #define STM32F4_EXTEN_MASK		GENMASK(29, 28)
+#define STM32F4_EXTSEL_SHIFT		24
+#define STM32F4_EXTSEL_MASK		GENMASK(27, 24)
 #define STM32F4_EOCS			BIT(10)
+#define STM32F4_DDS			BIT(9)
+#define STM32F4_DMA			BIT(8)
 #define STM32F4_ADON			BIT(0)
 
-/* STM32F4_ADC_SQR1 - bit fields */
-#define STM32F4_L_SHIFT			20
-#define STM32F4_L_MASK			GENMASK(23, 20)
-
-/* STM32F4_ADC_SQR3 - bit fields */
-#define STM32F4_SQ1_SHIFT		0
-#define STM32F4_SQ1_MASK		GENMASK(4, 0)
-
+#define STM32_ADC_MAX_SQ		16	/* SQ1..SQ16 */
 #define STM32_ADC_TIMEOUT_US		100000
 #define STM32_ADC_TIMEOUT	(msecs_to_jiffies(STM32_ADC_TIMEOUT_US / 1000))
 
+#define STM32_DMA_BUFFER_SIZE		PAGE_SIZE
+
+/* External trigger enable */
+enum stm32_adc_exten {
+	STM32_EXTEN_SWTRIG,
+	STM32_EXTEN_HWTRIG_RISING_EDGE,
+	STM32_EXTEN_HWTRIG_FALLING_EDGE,
+	STM32_EXTEN_HWTRIG_BOTH_EDGES,
+};
+
+/* extsel - trigger mux selection value */
+enum stm32_adc_extsel {
+	STM32_EXT0,
+	STM32_EXT1,
+	STM32_EXT2,
+	STM32_EXT3,
+	STM32_EXT4,
+	STM32_EXT5,
+	STM32_EXT6,
+	STM32_EXT7,
+	STM32_EXT8,
+	STM32_EXT9,
+	STM32_EXT10,
+	STM32_EXT11,
+	STM32_EXT12,
+	STM32_EXT13,
+	STM32_EXT14,
+	STM32_EXT15,
+};
+
+/**
+ * struct stm32_adc_trig_info - ADC trigger info
+ * @name:		name of the trigger, corresponding to its source
+ * @extsel:		trigger selection
+ */
+struct stm32_adc_trig_info {
+	const char *name;
+	enum stm32_adc_extsel extsel;
+};
+
+/**
+ * stm32_adc_regs - stm32 ADC misc registers & bitfield desc
+ * @reg:		register offset
+ * @mask:		bitfield mask
+ * @shift:		left shift
+ */
+struct stm32_adc_regs {
+	int reg;
+	int mask;
+	int shift;
+};
+
 /**
  * struct stm32_adc - private data of each ADC IIO instance
  * @common:		reference to ADC block common data
@@ -82,15 +139,29 @@
  * @clk:		clock for this adc instance
  * @irq:		interrupt for this adc instance
  * @lock:		spinlock
+ * @bufi:		data buffer index
+ * @num_conv:		expected number of scan conversions
+ * @trigger_polarity:	external trigger polarity (e.g. exten)
+ * @dma_chan:		dma channel
+ * @rx_buf:		dma rx buffer cpu address
+ * @rx_dma_buf:		dma rx buffer bus address
+ * @rx_buf_sz:		dma rx buffer size
  */
 struct stm32_adc {
 	struct stm32_adc_common	*common;
 	u32			offset;
 	struct completion	completion;
-	u16			*buffer;
+	u16			buffer[STM32_ADC_MAX_SQ];
 	struct clk		*clk;
 	int			irq;
 	spinlock_t		lock;		/* interrupt lock */
+	unsigned int		bufi;
+	unsigned int		num_conv;
+	u32			trigger_polarity;
+	struct dma_chan		*dma_chan;
+	u8			*rx_buf;
+	dma_addr_t		rx_dma_buf;
+	unsigned int		rx_buf_sz;
 };
 
 /**
@@ -126,6 +197,53 @@ static const struct stm32_adc_chan_spec stm32f4_adc123_channels[] = {
 };
 
 /**
+ * stm32f4_sq - describe regular sequence registers
+ * - L: sequence len (register & bit field)
+ * - SQ1..SQ16: sequence entries (register & bit field)
+ */
+static const struct stm32_adc_regs stm32f4_sq[STM32_ADC_MAX_SQ + 1] = {
+	/* L: len bit field description to be kept as first element */
+	{ STM32F4_ADC_SQR1, GENMASK(23, 20), 20 },
+	/* SQ1..SQ16 registers & bit fields (reg, mask, shift) */
+	{ STM32F4_ADC_SQR3, GENMASK(4, 0), 0 },
+	{ STM32F4_ADC_SQR3, GENMASK(9, 5), 5 },
+	{ STM32F4_ADC_SQR3, GENMASK(14, 10), 10 },
+	{ STM32F4_ADC_SQR3, GENMASK(19, 15), 15 },
+	{ STM32F4_ADC_SQR3, GENMASK(24, 20), 20 },
+	{ STM32F4_ADC_SQR3, GENMASK(29, 25), 25 },
+	{ STM32F4_ADC_SQR2, GENMASK(4, 0), 0 },
+	{ STM32F4_ADC_SQR2, GENMASK(9, 5), 5 },
+	{ STM32F4_ADC_SQR2, GENMASK(14, 10), 10 },
+	{ STM32F4_ADC_SQR2, GENMASK(19, 15), 15 },
+	{ STM32F4_ADC_SQR2, GENMASK(24, 20), 20 },
+	{ STM32F4_ADC_SQR2, GENMASK(29, 25), 25 },
+	{ STM32F4_ADC_SQR1, GENMASK(4, 0), 0 },
+	{ STM32F4_ADC_SQR1, GENMASK(9, 5), 5 },
+	{ STM32F4_ADC_SQR1, GENMASK(14, 10), 10 },
+	{ STM32F4_ADC_SQR1, GENMASK(19, 15), 15 },
+};
+
+/* STM32F4 external trigger sources for all instances */
+static struct stm32_adc_trig_info stm32f4_adc_trigs[] = {
+	{ TIM1_CH1, STM32_EXT0 },
+	{ TIM1_CH2, STM32_EXT1 },
+	{ TIM1_CH3, STM32_EXT2 },
+	{ TIM2_CH2, STM32_EXT3 },
+	{ TIM2_CH3, STM32_EXT4 },
+	{ TIM2_CH4, STM32_EXT5 },
+	{ TIM2_TRGO, STM32_EXT6 },
+	{ TIM3_CH1, STM32_EXT7 },
+	{ TIM3_TRGO, STM32_EXT8 },
+	{ TIM4_CH4, STM32_EXT9 },
+	{ TIM5_CH1, STM32_EXT10 },
+	{ TIM5_CH2, STM32_EXT11 },
+	{ TIM5_CH3, STM32_EXT12 },
+	{ TIM8_CH1, STM32_EXT13 },
+	{ TIM8_TRGO, STM32_EXT14 },
+	{}, /* sentinel */
+};
+
+/**
  * STM32 ADC registers access routines
  * @adc: stm32 adc instance
  * @reg: reg offset in adc instance
@@ -187,10 +305,21 @@ static void stm32_adc_conv_irq_disable(struct stm32_adc *adc)
 /**
  * stm32_adc_start_conv() - Start conversions for regular channels.
  * @adc: stm32 adc instance
+ * @dma: use dma to transfer conversion result
+ *
+ * Start conversions for regular channels.
+ * Also take care of normal or DMA mode. Circular DMA may be used for regular
+ * conversions, in IIO buffer modes. Otherwise, use ADC interrupt with direct
+ * DR read instead (e.g. read_raw, or triggered buffer mode without DMA).
  */
-static void stm32_adc_start_conv(struct stm32_adc *adc)
+static void stm32_adc_start_conv(struct stm32_adc *adc, bool dma)
 {
 	stm32_adc_set_bits(adc, STM32F4_ADC_CR1, STM32F4_SCAN);
+
+	if (dma)
+		stm32_adc_set_bits(adc, STM32F4_ADC_CR2,
+				   STM32F4_DMA | STM32F4_DDS);
+
 	stm32_adc_set_bits(adc, STM32F4_ADC_CR2, STM32F4_EOCS | STM32F4_ADON);
 
 	/* Wait for Power-up time (tSTAB from datasheet) */
@@ -207,10 +336,153 @@ static void stm32_adc_stop_conv(struct stm32_adc *adc)
 	stm32_adc_clr_bits(adc, STM32F4_ADC_SR, STM32F4_STRT);
 
 	stm32_adc_clr_bits(adc, STM32F4_ADC_CR1, STM32F4_SCAN);
-	stm32_adc_clr_bits(adc, STM32F4_ADC_CR2, STM32F4_ADON);
+	stm32_adc_clr_bits(adc, STM32F4_ADC_CR2,
+			   STM32F4_ADON | STM32F4_DMA | STM32F4_DDS);
+}
+
+/**
+ * stm32_adc_conf_scan_seq() - Build regular channels scan sequence
+ * @indio_dev: IIO device
+ * @scan_mask: channels to be converted
+ *
+ * Conversion sequence :
+ * Configure ADC scan sequence based on selected channels in scan_mask.
+ * Add channels to SQR registers, from scan_mask LSB to MSB, then
+ * program sequence len.
+ */
+static int stm32_adc_conf_scan_seq(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	const struct iio_chan_spec *chan;
+	u32 val, bit;
+	int i = 0;
+
+	for_each_set_bit(bit, scan_mask, indio_dev->masklength) {
+		chan = indio_dev->channels + bit;
+		/*
+		 * Assign one channel per SQ entry in regular
+		 * sequence, starting with SQ1.
+		 */
+		i++;
+		if (i > STM32_ADC_MAX_SQ)
+			return -EINVAL;
+
+		dev_dbg(&indio_dev->dev, "%s chan %d to SQ%d\n",
+			__func__, chan->channel, i);
+
+		val = stm32_adc_readl(adc, stm32f4_sq[i].reg);
+		val &= ~stm32f4_sq[i].mask;
+		val |= chan->channel << stm32f4_sq[i].shift;
+		stm32_adc_writel(adc, stm32f4_sq[i].reg, val);
+	}
+
+	if (!i)
+		return -EINVAL;
+
+	/* Sequence len */
+	val = stm32_adc_readl(adc, stm32f4_sq[0].reg);
+	val &= ~stm32f4_sq[0].mask;
+	val |= ((i - 1) << stm32f4_sq[0].shift);
+	stm32_adc_writel(adc, stm32f4_sq[0].reg, val);
+
+	return 0;
+}
+
+/**
+ * stm32_adc_get_trig_extsel() - Get external trigger selection
+ * @trig: trigger
+ *
+ * Returns trigger extsel value, if trig matches, -EINVAL otherwise.
+ */
+static int stm32_adc_get_trig_extsel(struct iio_trigger *trig)
+{
+	int i;
+
+	/* lookup triggers registered by stm32 timer trigger driver */
+	for (i = 0; stm32f4_adc_trigs[i].name; i++) {
+		/**
+		 * Checking both stm32 timer trigger type and trig name
+		 * should be safe against arbitrary trigger names.
+		 */
+		if (is_stm32_timer_trigger(trig) &&
+		    !strcmp(stm32f4_adc_trigs[i].name, trig->name)) {
+			return stm32f4_adc_trigs[i].extsel;
+		}
+	}
+
+	return -EINVAL;
 }
 
 /**
+ * stm32_adc_set_trig() - Set a regular trigger
+ * @indio_dev: IIO device
+ * @trig: IIO trigger
+ *
+ * Set trigger source/polarity (e.g. SW, or HW with polarity) :
+ * - if HW trigger disabled (e.g. trig == NULL, conversion launched by sw)
+ * - if HW trigger enabled, set source & polarity
+ */
+static int stm32_adc_set_trig(struct iio_dev *indio_dev,
+			      struct iio_trigger *trig)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	u32 val, extsel = 0, exten = STM32_EXTEN_SWTRIG;
+	unsigned long flags;
+	int ret;
+
+	if (trig) {
+		ret = stm32_adc_get_trig_extsel(trig);
+		if (ret < 0)
+			return ret;
+
+		/* set trigger source and polarity (default to rising edge) */
+		extsel = ret;
+		exten = adc->trigger_polarity + STM32_EXTEN_HWTRIG_RISING_EDGE;
+	}
+
+	spin_lock_irqsave(&adc->lock, flags);
+	val = stm32_adc_readl(adc, STM32F4_ADC_CR2);
+	val &= ~(STM32F4_EXTEN_MASK | STM32F4_EXTSEL_MASK);
+	val |= exten << STM32F4_EXTEN_SHIFT;
+	val |= extsel << STM32F4_EXTSEL_SHIFT;
+	stm32_adc_writel(adc, STM32F4_ADC_CR2, val);
+	spin_unlock_irqrestore(&adc->lock, flags);
+
+	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->trigger_polarity = 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->trigger_polarity;
+}
+
+static const char * const stm32_trig_pol_items[] = {
+	"rising-edge", "falling-edge", "both-edges",
+};
+
+static 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,
+};
+
+/**
  * stm32_adc_single_conv() - Performs a single conversion
  * @indio_dev: IIO device
  * @chan: IIO channel
@@ -228,28 +500,27 @@ static int stm32_adc_single_conv(struct iio_dev *indio_dev,
 	struct stm32_adc *adc = iio_priv(indio_dev);
 	long timeout;
 	u32 val;
-	u16 result;
 	int ret;
 
 	reinit_completion(&adc->completion);
 
-	adc->buffer = &result;
+	adc->bufi = 0;
 
-	/* Program chan number in regular sequence */
-	val = stm32_adc_readl(adc, STM32F4_ADC_SQR3);
-	val &= ~STM32F4_SQ1_MASK;
-	val |= chan->channel << STM32F4_SQ1_SHIFT;
-	stm32_adc_writel(adc, STM32F4_ADC_SQR3, val);
+	/* Program chan number in regular sequence (SQ1) */
+	val = stm32_adc_readl(adc, stm32f4_sq[1].reg);
+	val &= ~stm32f4_sq[1].mask;
+	val |= chan->channel << stm32f4_sq[1].shift;
+	stm32_adc_writel(adc, stm32f4_sq[1].reg, val);
 
 	/* Set regular sequence len (0 for 1 conversion) */
-	stm32_adc_clr_bits(adc, STM32F4_ADC_SQR1, STM32F4_L_MASK);
+	stm32_adc_clr_bits(adc, stm32f4_sq[0].reg, stm32f4_sq[0].mask);
 
 	/* Trigger detection disabled (conversion can be launched in SW) */
 	stm32_adc_clr_bits(adc, STM32F4_ADC_CR2, STM32F4_EXTEN_MASK);
 
 	stm32_adc_conv_irq_enable(adc);
 
-	stm32_adc_start_conv(adc);
+	stm32_adc_start_conv(adc, false);
 
 	timeout = wait_for_completion_interruptible_timeout(
 					&adc->completion, STM32_ADC_TIMEOUT);
@@ -258,7 +529,7 @@ static int stm32_adc_single_conv(struct iio_dev *indio_dev,
 	} else if (timeout < 0) {
 		ret = timeout;
 	} else {
-		*res = result;
+		*res = adc->buffer[0];
 		ret = IIO_VAL_INT;
 	}
 
@@ -301,17 +572,73 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 static irqreturn_t stm32_adc_isr(int irq, void *data)
 {
 	struct stm32_adc *adc = data;
+	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
 	u32 status = stm32_adc_readl(adc, STM32F4_ADC_SR);
 
 	if (status & STM32F4_EOC) {
-		*adc->buffer = stm32_adc_readw(adc, STM32F4_ADC_DR);
-		complete(&adc->completion);
+		/* Reading DR also clears EOC status flag */
+		adc->buffer[adc->bufi] = stm32_adc_readw(adc, STM32F4_ADC_DR);
+		if (iio_buffer_enabled(indio_dev)) {
+			adc->bufi++;
+			if (adc->bufi >= adc->num_conv) {
+				stm32_adc_conv_irq_disable(adc);
+				iio_trigger_poll(indio_dev->trig);
+			}
+		} else {
+			complete(&adc->completion);
+		}
 		return IRQ_HANDLED;
 	}
 
 	return IRQ_NONE;
 }
 
+/**
+ * stm32_adc_validate_trigger() - validate trigger for stm32 adc
+ * @indio_dev: IIO device
+ * @trig: new trigger
+ *
+ * Returns: 0 if trig matches one of the triggers registered by stm32 adc
+ * driver, -EINVAL otherwise.
+ */
+static int stm32_adc_validate_trigger(struct iio_dev *indio_dev,
+				      struct iio_trigger *trig)
+{
+	return stm32_adc_get_trig_extsel(trig) < 0 ? -EINVAL : 0;
+}
+
+static int stm32_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	unsigned int watermark = STM32_DMA_BUFFER_SIZE / 2;
+
+	/*
+	 * dma cyclic transfers are used, buffer is split into two periods.
+	 * There should be :
+	 * - always one buffer (period) dma is working on
+	 * - one buffer (period) driver can push with iio_trigger_poll().
+	 */
+	watermark = min(watermark, val * (unsigned)(sizeof(u16)));
+	adc->rx_buf_sz = watermark * 2;
+
+	return 0;
+}
+
+static int stm32_adc_update_scan_mode(struct iio_dev *indio_dev,
+				      const unsigned long *scan_mask)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	int ret;
+
+	adc->num_conv = bitmap_weight(scan_mask, indio_dev->masklength);
+
+	ret = stm32_adc_conf_scan_seq(indio_dev, scan_mask);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int stm32_adc_of_xlate(struct iio_dev *indio_dev,
 			      const struct of_phandle_args *iiospec)
 {
@@ -350,11 +677,199 @@ static int stm32_adc_debugfs_reg_access(struct iio_dev *indio_dev,
 
 static const struct iio_info stm32_adc_iio_info = {
 	.read_raw = stm32_adc_read_raw,
+	.validate_trigger = stm32_adc_validate_trigger,
+	.hwfifo_set_watermark = stm32_adc_set_watermark,
+	.update_scan_mode = stm32_adc_update_scan_mode,
 	.debugfs_reg_access = stm32_adc_debugfs_reg_access,
 	.of_xlate = stm32_adc_of_xlate,
 	.driver_module = THIS_MODULE,
 };
 
+static unsigned int stm32_adc_dma_residue(struct stm32_adc *adc)
+{
+	struct dma_tx_state state;
+	enum dma_status status;
+
+	status = dmaengine_tx_status(adc->dma_chan,
+				     adc->dma_chan->cookie,
+				     &state);
+	if (status == DMA_IN_PROGRESS) {
+		/* Residue is size in bytes from end of buffer */
+		unsigned int i = adc->rx_buf_sz - state.residue;
+		unsigned int size;
+
+		/* Return available bytes */
+		if (i >= adc->bufi)
+			size = i - adc->bufi;
+		else
+			size = adc->rx_buf_sz + i - adc->bufi;
+
+		return size;
+	}
+
+	return 0;
+}
+
+static void stm32_adc_dma_buffer_done(void *data)
+{
+	struct iio_dev *indio_dev = data;
+
+	iio_trigger_poll_chained(indio_dev->trig);
+}
+
+static int stm32_adc_dma_start(struct iio_dev *indio_dev)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	struct dma_async_tx_descriptor *desc;
+	dma_cookie_t cookie;
+	int ret;
+
+	if (!adc->dma_chan)
+		return 0;
+
+	dev_dbg(&indio_dev->dev, "%s size=%d watermark=%d\n", __func__,
+		adc->rx_buf_sz, adc->rx_buf_sz / 2);
+
+	/* Prepare a DMA cyclic transaction */
+	desc = dmaengine_prep_dma_cyclic(adc->dma_chan,
+					 adc->rx_dma_buf,
+					 adc->rx_buf_sz, adc->rx_buf_sz / 2,
+					 DMA_DEV_TO_MEM,
+					 DMA_PREP_INTERRUPT);
+	if (!desc)
+		return -EBUSY;
+
+	desc->callback = stm32_adc_dma_buffer_done;
+	desc->callback_param = indio_dev;
+
+	cookie = dmaengine_submit(desc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		dmaengine_terminate_all(adc->dma_chan);
+		return ret;
+	}
+
+	/* Issue pending DMA requests */
+	dma_async_issue_pending(adc->dma_chan);
+
+	return 0;
+}
+
+static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	int ret;
+
+	ret = stm32_adc_set_trig(indio_dev, indio_dev->trig);
+	if (ret) {
+		dev_err(&indio_dev->dev, "Can't set trigger\n");
+		return ret;
+	}
+
+	ret = stm32_adc_dma_start(indio_dev);
+	if (ret) {
+		dev_err(&indio_dev->dev, "Can't start dma\n");
+		goto err_clr_trig;
+	}
+
+	ret = iio_triggered_buffer_postenable(indio_dev);
+	if (ret < 0)
+		goto err_stop_dma;
+
+	/* Reset adc buffer index */
+	adc->bufi = 0;
+
+	if (!adc->dma_chan)
+		stm32_adc_conv_irq_enable(adc);
+
+	stm32_adc_start_conv(adc, !!adc->dma_chan);
+
+	return 0;
+
+err_stop_dma:
+	if (adc->dma_chan)
+		dmaengine_terminate_all(adc->dma_chan);
+err_clr_trig:
+	stm32_adc_set_trig(indio_dev, NULL);
+
+	return ret;
+}
+
+static int stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	int ret;
+
+	stm32_adc_stop_conv(adc);
+	if (!adc->dma_chan)
+		stm32_adc_conv_irq_disable(adc);
+
+	ret = iio_triggered_buffer_predisable(indio_dev);
+	if (ret < 0)
+		dev_err(&indio_dev->dev, "predisable failed\n");
+
+	if (adc->dma_chan)
+		dmaengine_terminate_all(adc->dma_chan);
+
+	if (stm32_adc_set_trig(indio_dev, NULL))
+		dev_err(&indio_dev->dev, "Can't clear trigger\n");
+
+	return ret;
+}
+
+static const struct iio_buffer_setup_ops stm32_adc_buffer_setup_ops = {
+	.postenable = &stm32_adc_buffer_postenable,
+	.predisable = &stm32_adc_buffer_predisable,
+};
+
+static irqreturn_t stm32_adc_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct stm32_adc *adc = iio_priv(indio_dev);
+
+	dev_dbg(&indio_dev->dev, "%s bufi=%d\n", __func__, adc->bufi);
+
+	if (!adc->dma_chan) {
+		/* reset buffer index */
+		adc->bufi = 0;
+		iio_push_to_buffers_with_timestamp(indio_dev, adc->buffer,
+						   pf->timestamp);
+	} else {
+		int residue = stm32_adc_dma_residue(adc);
+
+		while (residue >= indio_dev->scan_bytes) {
+			u16 *buffer = (u16 *)&adc->rx_buf[adc->bufi];
+
+			iio_push_to_buffers_with_timestamp(indio_dev, buffer,
+							   pf->timestamp);
+			residue -= indio_dev->scan_bytes;
+			adc->bufi += indio_dev->scan_bytes;
+			if (adc->bufi >= adc->rx_buf_sz)
+				adc->bufi = 0;
+		}
+	}
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	/* re-enable eoc irq */
+	if (!adc->dma_chan)
+		stm32_adc_conv_irq_enable(adc);
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_chan_spec_ext_info stm32_adc_ext_info[] = {
+	IIO_ENUM("trigger_polarity", IIO_SHARED_BY_ALL, &stm32_adc_trig_pol),
+	{
+		.name = "trigger_polarity_available",
+		.shared = IIO_SHARED_BY_ALL,
+		.read = iio_enum_available_read,
+		.private = (uintptr_t)&stm32_adc_trig_pol,
+	},
+	{},
+};
+
 static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
 				    struct iio_chan_spec *chan,
 				    const struct stm32_adc_chan_spec *channel,
@@ -370,6 +885,7 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
 	chan->scan_type.sign = 'u';
 	chan->scan_type.realbits = 12;
 	chan->scan_type.storagebits = 16;
+	chan->ext_info = stm32_adc_ext_info;
 }
 
 static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
@@ -410,6 +926,45 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
 	return 0;
 }
 
+static int stm32_adc_dma_request(struct iio_dev *indio_dev)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	struct dma_slave_config config;
+	int ret;
+
+	adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
+	if (!adc->dma_chan)
+		return 0;
+
+	adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
+					 STM32_DMA_BUFFER_SIZE,
+					 &adc->rx_dma_buf, GFP_KERNEL);
+	if (!adc->rx_buf) {
+		ret = -ENOMEM;
+		goto err_release;
+	}
+
+	/* Configure DMA channel to read data register */
+	memset(&config, 0, sizeof(config));
+	config.src_addr = (dma_addr_t)adc->common->phys_base;
+	config.src_addr += adc->offset + STM32F4_ADC_DR;
+	config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+
+	ret = dmaengine_slave_config(adc->dma_chan, &config);
+	if (ret)
+		goto err_free;
+
+	return 0;
+
+err_free:
+	dma_free_coherent(adc->dma_chan->device->dev, STM32_DMA_BUFFER_SIZE,
+			  adc->rx_buf, adc->rx_dma_buf);
+err_release:
+	dma_release_channel(adc->dma_chan);
+
+	return ret;
+}
+
 static int stm32_adc_probe(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev;
@@ -471,14 +1026,37 @@ static int stm32_adc_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto err_clk_disable;
 
+	ret = stm32_adc_dma_request(indio_dev);
+	if (ret < 0)
+		goto err_clk_disable;
+
+	ret = iio_triggered_buffer_setup(indio_dev,
+					 &iio_pollfunc_store_time,
+					 &stm32_adc_trigger_handler,
+					 &stm32_adc_buffer_setup_ops);
+	if (ret) {
+		dev_err(&pdev->dev, "buffer setup failed\n");
+		goto err_dma_disable;
+	}
+
 	ret = iio_device_register(indio_dev);
 	if (ret) {
 		dev_err(&pdev->dev, "iio dev register failed\n");
-		goto err_clk_disable;
+		goto err_buffer_cleanup;
 	}
 
 	return 0;
 
+err_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+err_dma_disable:
+	if (adc->dma_chan) {
+		dma_free_coherent(adc->dma_chan->device->dev,
+				  STM32_DMA_BUFFER_SIZE,
+				  adc->rx_buf, adc->rx_dma_buf);
+		dma_release_channel(adc->dma_chan);
+	}
 err_clk_disable:
 	clk_disable_unprepare(adc->clk);
 
@@ -491,6 +1069,13 @@ static int stm32_adc_remove(struct platform_device *pdev)
 	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
 
 	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	if (adc->dma_chan) {
+		dma_free_coherent(adc->dma_chan->device->dev,
+				  STM32_DMA_BUFFER_SIZE,
+				  adc->rx_buf, adc->rx_dma_buf);
+		dma_release_channel(adc->dma_chan);
+	}
 	clk_disable_unprepare(adc->clk);
 
 	return 0;