Enable the watermark feature of the adxl345 sensor. The feature uses a
FIFO to be configured by the IIO fifo sysfs handles. The sensor
configures the FIFO to streaming mode for measurements, or bypass for
configuration. The sensor issues an interrupt on the configured line to
signal several signals (data available, overrun or watermark reached).
The setup allows for extension of further features based on the
interrupt handler and the FIFO setup.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
---
 drivers/iio/accel/adxl345_core.c | 39 ++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index f7b937fb16..07c336211f 100644
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -870,6 +870,45 @@ int adxl345_core_probe(struct device *dev, struct regmap *regmap,
 		if (ret)
 			return dev_err_probe(dev, ret, "Failed to setup triggered buffer\n");
 
+		dev_dbg(dev, "IRQ: allocating data ready trigger\n");
+		st->trig_dready = devm_iio_trigger_alloc(dev,
+							 "%s-dev%d-dready",
+							 indio_dev->name,
+							 iio_device_id(indio_dev));
+		if (!st->trig_dready)
+			return dev_err_probe(dev, -ENOMEM,
+					     "Failed to setup triggered buffer\n");
+		dev_dbg(dev, "IRQ: allocating data ready trigger ok\n");
+
+		st->trig_dready->ops = &adxl34x_trig_dready_ops;
+		dev_dbg(dev, "IRQ: Setting data ready trigger ops ok\n");
+
+		iio_trigger_set_drvdata(st->trig_dready, indio_dev);
+		dev_dbg(dev, "IRQ: Setting up data ready trigger as driver data ok\n");
+
+		ret = devm_iio_trigger_register(dev, st->trig_dready);
+		if (ret < 0)
+			return dev_err_probe(dev, ret,
+					     "Failed to register dready trigger\n");
+		dev_dbg(dev, "Registering data ready trigger ok\n");
+
+		indio_dev->trig = iio_trigger_get(st->trig_dready);
+
+		dev_dbg(dev, "Requesting threaded IRQ, indio_dev->name '%s'\n",
+			indio_dev->name);
+
+		ret = devm_request_threaded_irq(dev, st->irq,
+						iio_trigger_generic_data_rdy_poll,
+						NULL,
+						IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+						indio_dev->name, st->trig_dready);
+		if (ret < 0)
+			return dev_err_probe(dev, ret, "Failed to request IRQ handler\n");
+		dev_dbg(dev, "Requesting threaded IRQ handler ok\n");
+
+		/* Cleanup */
+		adxl345_empty_fifo(st);
+
 	} else { /* Initialization to prepare for FIFO_BYPASS mode (fallback) */
 
 		/* The following defaults to 0x00, anyway */
-- 
2.39.5