iio: imu: st_lsm6dsx: add wakeup-source option

This add ways for the SoC to wake from accelerometer wake events.

In the suspend function we skip disabling the sensor if wakeup-source
and events are activated.
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Reviewed-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c

@@ -1858,6 +1858,9 @@ int st_lsm6dsx_probe(struct device *dev, int irq, int hw_id,
 			return err;
 	}
 
+	if (dev->of_node && of_property_read_bool(dev->of_node, "wakeup-source"))
+		device_init_wakeup(dev, true);
+
 	return 0;
 }
 EXPORT_SYMBOL(st_lsm6dsx_probe);
@@ -1876,6 +1879,13 @@ static int __maybe_unused st_lsm6dsx_suspend(struct device *dev)
 		if (!(hw->enable_mask & BIT(sensor->id)))
 			continue;
 
+		if (device_may_wakeup(dev) &&
+		    sensor->id == ST_LSM6DSX_ID_ACC && hw->enable_event) {
+			/* Enable wake from IRQ */
+			enable_irq_wake(hw->irq);
+			continue;
+		}
+
 		if (sensor->id == ST_LSM6DSX_ID_EXT0 ||
 		    sensor->id == ST_LSM6DSX_ID_EXT1 ||
 		    sensor->id == ST_LSM6DSX_ID_EXT2)
@@ -1905,6 +1915,10 @@ static int __maybe_unused st_lsm6dsx_resume(struct device *dev)
 			continue;
 
 		sensor = iio_priv(hw->iio_devs[i]);
+		if (device_may_wakeup(dev) &&
+		    sensor->id == ST_LSM6DSX_ID_ACC && hw->enable_event)
+			disable_irq_wake(hw->irq);
+
 		if (!(hw->suspend_mask & BIT(sensor->id)))
 			continue;