1 files changed, 109 insertions, 45 deletions

diff --git a/drivers/iio/common/st_sensors/st_sensors_trigger.c b/drivers/iio/common/st_sensors/st_sensors_trigger.c
index fab494d71951..e66f12ee8a55 100644
--- a/drivers/iio/common/st_sensors/st_sensors_trigger.c
+++ b/drivers/iio/common/st_sensors/st_sensors_trigger.c
@@ -18,6 +18,50 @@
 #include "st_sensors_core.h"
 
 /**
+ * st_sensors_new_samples_available() - check if more samples came in
+ * returns:
+ * 0 - no new samples available
+ * 1 - new samples available
+ * negative - error or unknown
+ */
+static int st_sensors_new_samples_available(struct iio_dev *indio_dev,
+					    struct st_sensor_data *sdata)
+{
+	u8 status;
+	int ret;
+
+	/* How would I know if I can't check it? */
+	if (!sdata->sensor_settings->drdy_irq.addr_stat_drdy)
+		return -EINVAL;
+
+	/* No scan mask, no interrupt */
+	if (!indio_dev->active_scan_mask)
+		return 0;
+
+	ret = sdata->tf->read_byte(&sdata->tb, sdata->dev,
+			sdata->sensor_settings->drdy_irq.addr_stat_drdy,
+			&status);
+	if (ret < 0) {
+		dev_err(sdata->dev,
+			"error checking samples available\n");
+		return ret;
+	}
+	/*
+	 * the lower bits of .active_scan_mask[0] is directly mapped
+	 * to the channels on the sensor: either bit 0 for
+	 * one-dimensional sensors, or e.g. x,y,z for accelerometers,
+	 * gyroscopes or magnetometers. No sensor use more than 3
+	 * channels, so cut the other status bits here.
+	 */
+	status &= 0x07;
+
+	if (status & (u8)indio_dev->active_scan_mask[0])
+		return 1;
+
+	return 0;
+}
+
+/**
  * st_sensors_irq_handler() - top half of the IRQ-based triggers
  * @irq: irq number
  * @p: private handler data
@@ -43,44 +87,43 @@ irqreturn_t st_sensors_irq_thread(int irq, void *p)
 	struct iio_trigger *trig = p;
 	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
 	struct st_sensor_data *sdata = iio_priv(indio_dev);
-	int ret;
 
 	/*
 	 * If this trigger is backed by a hardware interrupt and we have a
-	 * status register, check if this IRQ came from us
+	 * status register, check if this IRQ came from us. Notice that
+	 * we will process also if st_sensors_new_samples_available()
+	 * returns negative: if we can't check status, then poll
+	 * unconditionally.
 	 */
-	if (sdata->sensor_settings->drdy_irq.addr_stat_drdy) {
-		u8 status;
-
-		ret = sdata->tf->read_byte(&sdata->tb, sdata->dev,
-			   sdata->sensor_settings->drdy_irq.addr_stat_drdy,
-			   &status);
-		if (ret < 0) {
-			dev_err(sdata->dev, "could not read channel status\n");
-			goto out_poll;
-		}
-		/*
-		 * the lower bits of .active_scan_mask[0] is directly mapped
-		 * to the channels on the sensor: either bit 0 for
-		 * one-dimensional sensors, or e.g. x,y,z for accelerometers,
-		 * gyroscopes or magnetometers. No sensor use more than 3
-		 * channels, so cut the other status bits here.
-		 */
-		status &= 0x07;
+	if (sdata->hw_irq_trigger &&
+	    st_sensors_new_samples_available(indio_dev, sdata)) {
+		iio_trigger_poll_chained(p);
+	} else {
+		dev_dbg(sdata->dev, "spurious IRQ\n");
+		return IRQ_NONE;
+	}
 
-		/*
-		 * If this was not caused by any channels on this sensor,
-		 * return IRQ_NONE
-		 */
-		if (!indio_dev->active_scan_mask)
-			return IRQ_NONE;
-		if (!(status & (u8)indio_dev->active_scan_mask[0]))
-			return IRQ_NONE;
+	/*
+	 * If we have proper level IRQs the handler will be re-entered if
+	 * the line is still active, so return here and come back in through
+	 * the top half if need be.
+	 */
+	if (!sdata->edge_irq)
+		return IRQ_HANDLED;
+
+	/*
+	 * If we are using egde IRQs, new samples arrived while processing
+	 * the IRQ and those may be missed unless we pick them here, so poll
+	 * again. If the sensor delivery frequency is very high, this thread
+	 * turns into a polled loop handler.
+	 */
+	while (sdata->hw_irq_trigger &&
+	       st_sensors_new_samples_available(indio_dev, sdata)) {
+		dev_dbg(sdata->dev, "more samples came in during polling\n");
+		sdata->hw_timestamp = iio_get_time_ns(indio_dev);
+		iio_trigger_poll_chained(p);
 	}
 
-out_poll:
-	/* It's our IRQ: proceed to handle the register polling */
-	iio_trigger_poll_chained(p);
 	return IRQ_HANDLED;
 }
 
@@ -107,13 +150,18 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev,
 	 * If the IRQ is triggered on falling edge, we need to mark the
 	 * interrupt as active low, if the hardware supports this.
 	 */
-	if (irq_trig == IRQF_TRIGGER_FALLING) {
+	switch(irq_trig) {
+	case IRQF_TRIGGER_FALLING:
+	case IRQF_TRIGGER_LOW:
 		if (!sdata->sensor_settings->drdy_irq.addr_ihl) {
 			dev_err(&indio_dev->dev,
-				"falling edge specified for IRQ but hardware "
-				"only support rising edge, will request "
-				"rising edge\n");
-			irq_trig = IRQF_TRIGGER_RISING;
+				"falling/low specified for IRQ "
+				"but hardware only support rising/high: "
+				"will request rising/high\n");
+			if (irq_trig == IRQF_TRIGGER_FALLING)
+				irq_trig = IRQF_TRIGGER_RISING;
+			if (irq_trig == IRQF_TRIGGER_LOW)
+				irq_trig = IRQF_TRIGGER_HIGH;
 		} else {
 			/* Set up INT active low i.e. falling edge */
 			err = st_sensors_write_data_with_mask(indio_dev,
@@ -122,20 +170,39 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev,
 			if (err < 0)
 				goto iio_trigger_free;
 			dev_info(&indio_dev->dev,
-				 "interrupts on the falling edge\n");
+				 "interrupts on the falling edge or "
+				 "active low level\n");
 		}
-	} else if (irq_trig == IRQF_TRIGGER_RISING) {
+		break;
+	case IRQF_TRIGGER_RISING:
 		dev_info(&indio_dev->dev,
 			 "interrupts on the rising edge\n");
-
-	} else {
+		break;
+	case IRQF_TRIGGER_HIGH:
+		dev_info(&indio_dev->dev,
+			 "interrupts active high level\n");
+		break;
+	default:
+		/* This is the most preferred mode, if possible */
 		dev_err(&indio_dev->dev,
-		"unsupported IRQ trigger specified (%lx), only "
-			"rising and falling edges supported, enforce "
+			"unsupported IRQ trigger specified (%lx), enforce "
 			"rising edge\n", irq_trig);
 		irq_trig = IRQF_TRIGGER_RISING;
 	}
 
+	/* Tell the interrupt handler that we're dealing with edges */
+	if (irq_trig == IRQF_TRIGGER_FALLING ||
+	    irq_trig == IRQF_TRIGGER_RISING)
+		sdata->edge_irq = true;
+	else
+		/*
+		 * If we're not using edges (i.e. level interrupts) we
+		 * just mask off the IRQ, handle one interrupt, then
+		 * if the line is still low, we return to the
+		 * interrupt handler top half again and start over.
+		 */
+		irq_trig |= IRQF_ONESHOT;
+
 	/*
 	 * If the interrupt pin is Open Drain, by definition this
 	 * means that the interrupt line may be shared with other
@@ -148,9 +215,6 @@ int st_sensors_allocate_trigger(struct iio_dev *indio_dev,
 	    sdata->sensor_settings->drdy_irq.addr_stat_drdy)
 		irq_trig |= IRQF_SHARED;
 
-	/* Let's create an interrupt thread masking the hard IRQ here */
-	irq_trig |= IRQF_ONESHOT;
-
 	err = request_threaded_irq(sdata->get_irq_data_ready(indio_dev),
 			st_sensors_irq_handler,
 			st_sensors_irq_thread,