1 files changed, 67 insertions, 4 deletions

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 3b291d72701c..80c3f963527b 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -117,7 +117,9 @@ struct stm32_adc_regs {
  * struct stm32_adc_regspec - stm32 registers definition
  * @dr:			data register offset
  * @ier_eoc:		interrupt enable register & eocie bitfield
+ * @ier_ovr:		interrupt enable register & overrun bitfield
  * @isr_eoc:		interrupt status register & eoc bitfield
+ * @isr_ovr:		interrupt status register & overrun bitfield
  * @sqr:		reference to sequence registers array
  * @exten:		trigger control register & bitfield
  * @extsel:		trigger selection register & bitfield
@@ -128,7 +130,9 @@ struct stm32_adc_regs {
 struct stm32_adc_regspec {
 	const u32 dr;
 	const struct stm32_adc_regs ier_eoc;
+	const struct stm32_adc_regs ier_ovr;
 	const struct stm32_adc_regs isr_eoc;
+	const struct stm32_adc_regs isr_ovr;
 	const struct stm32_adc_regs *sqr;
 	const struct stm32_adc_regs exten;
 	const struct stm32_adc_regs extsel;
@@ -337,7 +341,9 @@ static const unsigned int stm32f4_adc_smp_cycles[STM32_ADC_MAX_SMP + 1] = {
 static const struct stm32_adc_regspec stm32f4_adc_regspec = {
 	.dr = STM32F4_ADC_DR,
 	.ier_eoc = { STM32F4_ADC_CR1, STM32F4_EOCIE },
+	.ier_ovr = { STM32F4_ADC_CR1, STM32F4_OVRIE },
 	.isr_eoc = { STM32F4_ADC_SR, STM32F4_EOC },
+	.isr_ovr = { STM32F4_ADC_SR, STM32F4_OVR },
 	.sqr = stm32f4_sq,
 	.exten = { STM32F4_ADC_CR2, STM32F4_EXTEN_MASK, STM32F4_EXTEN_SHIFT },
 	.extsel = { STM32F4_ADC_CR2, STM32F4_EXTSEL_MASK,
@@ -429,7 +435,9 @@ static const unsigned int stm32h7_adc_smp_cycles[STM32_ADC_MAX_SMP + 1] = {
 static const struct stm32_adc_regspec stm32h7_adc_regspec = {
 	.dr = STM32H7_ADC_DR,
 	.ier_eoc = { STM32H7_ADC_IER, STM32H7_EOCIE },
+	.ier_ovr = { STM32H7_ADC_IER, STM32H7_OVRIE },
 	.isr_eoc = { STM32H7_ADC_ISR, STM32H7_EOC },
+	.isr_ovr = { STM32H7_ADC_ISR, STM32H7_OVR },
 	.sqr = stm32h7_sq,
 	.exten = { STM32H7_ADC_CFGR, STM32H7_EXTEN_MASK, STM32H7_EXTEN_SHIFT },
 	.extsel = { STM32H7_ADC_CFGR, STM32H7_EXTSEL_MASK,
@@ -506,6 +514,18 @@ static void stm32_adc_conv_irq_disable(struct stm32_adc *adc)
 			   adc->cfg->regs->ier_eoc.mask);
 }
 
+static void stm32_adc_ovr_irq_enable(struct stm32_adc *adc)
+{
+	stm32_adc_set_bits(adc, adc->cfg->regs->ier_ovr.reg,
+			   adc->cfg->regs->ier_ovr.mask);
+}
+
+static void stm32_adc_ovr_irq_disable(struct stm32_adc *adc)
+{
+	stm32_adc_clr_bits(adc, adc->cfg->regs->ier_ovr.reg,
+			   adc->cfg->regs->ier_ovr.mask);
+}
+
 static void stm32_adc_set_res(struct stm32_adc *adc)
 {
 	const struct stm32_adc_regs *res = &adc->cfg->regs->res;
@@ -1205,6 +1225,19 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 	}
 }
 
+static irqreturn_t stm32_adc_threaded_isr(int irq, void *data)
+{
+	struct stm32_adc *adc = data;
+	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	const struct stm32_adc_regspec *regs = adc->cfg->regs;
+	u32 status = stm32_adc_readl(adc, regs->isr_eoc.reg);
+
+	if (status & regs->isr_ovr.mask)
+		dev_err(&indio_dev->dev, "Overrun, stopping: restart needed\n");
+
+	return IRQ_HANDLED;
+}
+
 static irqreturn_t stm32_adc_isr(int irq, void *data)
 {
 	struct stm32_adc *adc = data;
@@ -1212,6 +1245,19 @@ static irqreturn_t stm32_adc_isr(int irq, void *data)
 	const struct stm32_adc_regspec *regs = adc->cfg->regs;
 	u32 status = stm32_adc_readl(adc, regs->isr_eoc.reg);
 
+	if (status & regs->isr_ovr.mask) {
+		/*
+		 * Overrun occurred on regular conversions: data for wrong
+		 * channel may be read. Unconditionally disable interrupts
+		 * to stop processing data and print error message.
+		 * Restarting the capture can be done by disabling, then
+		 * re-enabling it (e.g. write 0, then 1 to buffer/enable).
+		 */
+		stm32_adc_ovr_irq_disable(adc);
+		stm32_adc_conv_irq_disable(adc);
+		return IRQ_WAKE_THREAD;
+	}
+
 	if (status & regs->isr_eoc.mask) {
 		/* Reading DR also clears EOC status flag */
 		adc->buffer[adc->bufi] = stm32_adc_readw(adc, regs->dr);
@@ -1441,6 +1487,8 @@ static int __stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
 	/* Reset adc buffer index */
 	adc->bufi = 0;
 
+	stm32_adc_ovr_irq_enable(adc);
+
 	if (!adc->dma_chan)
 		stm32_adc_conv_irq_enable(adc);
 
@@ -1481,6 +1529,8 @@ static void __stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
 	if (!adc->dma_chan)
 		stm32_adc_conv_irq_disable(adc);
 
+	stm32_adc_ovr_irq_disable(adc);
+
 	if (adc->dma_chan)
 		dmaengine_terminate_sync(adc->dma_chan);
 
@@ -1746,9 +1796,21 @@ static int stm32_adc_dma_request(struct iio_dev *indio_dev)
 	struct dma_slave_config config;
 	int ret;
 
-	adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
-	if (!adc->dma_chan)
+	adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
+	if (IS_ERR(adc->dma_chan)) {
+		ret = PTR_ERR(adc->dma_chan);
+		if (ret != -ENODEV) {
+			if (ret != -EPROBE_DEFER)
+				dev_err(&indio_dev->dev,
+					"DMA channel request failed with %d\n",
+					ret);
+			return ret;
+		}
+
+		/* DMA is optional: fall back to IRQ mode */
+		adc->dma_chan = NULL;
 		return 0;
+	}
 
 	adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
 					 STM32_DMA_BUFFER_SIZE,
@@ -1818,8 +1880,9 @@ static int stm32_adc_probe(struct platform_device *pdev)
 	if (adc->irq < 0)
 		return adc->irq;
 
-	ret = devm_request_irq(&pdev->dev, adc->irq, stm32_adc_isr,
-			       0, pdev->name, adc);
+	ret = devm_request_threaded_irq(&pdev->dev, adc->irq, stm32_adc_isr,
+					stm32_adc_threaded_isr,
+					0, pdev->name, adc);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to request IRQ\n");
 		return ret;