iio: accel: fxls8962af: add wake on event

This adds 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.

If buffered reads are enabled they will be deactivated before suspend.
As the onboard buffer is only holding up to 32 12-bit X/Y/Z data
triplets.

Signed-off-by: Sean Nyekjaer <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/accel/fxls8962af-core.c

···
 	} scan;
 	int64_t timestamp, old_timestamp;	/* Only used in hw fifo mode. */
 	struct iio_mount_matrix orientation;
+	int irq;
 	u8 watermark;
 	u8 enable_event;
 	u16 lower_thres;
···
 	data = iio_priv(indio_dev);
 	dev_set_drvdata(dev, indio_dev);
 	data->regmap = regmap;
+	data->irq = irq;
 
 	ret = iio_read_mount_matrix(dev, &data->orientation);
 	if (ret)
···
 	if (ret)
 		return ret;
 
+	if (device_property_read_bool(dev, "wakeup-source"))
+		device_init_wakeup(dev, true);
+
 	return devm_iio_device_register(dev, indio_dev);
 }
 EXPORT_SYMBOL_GPL(fxls8962af_core_probe);
···
 	return fxls8962af_active(data);
 }
 
+static int __maybe_unused fxls8962af_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct fxls8962af_data *data = iio_priv(indio_dev);
+
+	if (device_may_wakeup(dev) && data->enable_event) {
+		enable_irq_wake(data->irq);
+
+		/*
+		 * Disable buffer, as the buffer is so small the device will wake
+		 * almost immediately.
+		 */
+		if (iio_buffer_enabled(indio_dev))
+			fxls8962af_buffer_predisable(indio_dev);
+	} else {
+		fxls8962af_runtime_suspend(dev);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused fxls8962af_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct fxls8962af_data *data = iio_priv(indio_dev);
+
+	if (device_may_wakeup(dev) && data->enable_event) {
+		disable_irq_wake(data->irq);
+
+		if (iio_buffer_enabled(indio_dev))
+			fxls8962af_buffer_postenable(indio_dev);
+	} else {
+		fxls8962af_runtime_resume(dev);
+	}
+
+	return 0;
+}
+
 const struct dev_pm_ops fxls8962af_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
-				pm_runtime_force_resume)
+	SET_SYSTEM_SLEEP_PM_OPS(fxls8962af_suspend, fxls8962af_resume)
 	SET_RUNTIME_PM_OPS(fxls8962af_runtime_suspend,
 			   fxls8962af_runtime_resume, NULL)
 };