[PATCH v3 1/4] iio:trigger: Add helper function to verify that a trigger belongs to the same device

[Lars-Peter Clausen <lars@metafoo.de>]

Some triggers can only be attached to the IIO device that corresponds to
the same physical device. Currently each driver that requires this
implements its own trigger validation function.

Introduce a new helper function called iio_trigger_validate_own_device()
that can be used to do this check. Having a common implementation avoids
code duplication and unnecessary boiler-plate code.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
New in v3
---
 drivers/iio/industrialio-trigger.c | 21 +++++++++++++++++++++
 include/linux/iio/trigger.h        |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index e1e1048..05b2011 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -717,6 +717,27 @@ bool iio_trigger_using_own(struct iio_dev *indio_dev)
 }
 EXPORT_SYMBOL(iio_trigger_using_own);
 
+/**
+ * iio_trigger_validate_own_device - Check if a trigger and IIO device belong to
+ *  the same device
+ * @trig: The IIO trigger to check
+ * @indio_devdev: the IIO device to check
+ *
+ * This function can be used as the validate_device callback for triggers that
+ * can only be attached to their own device.
+ *
+ * Return: 0 if both the trigger and the IIO device belong to the same
+ * device, -EINVAL otherwise.
+ */
+int iio_trigger_validate_own_device(struct iio_trigger *trig,
+	struct iio_dev *indio_dev)
+{
+	if (indio_dev->dev.parent != trig->dev.parent)
+		return -EINVAL;
+	return 0;
+}
+EXPORT_SYMBOL(iio_trigger_validate_own_device);
+
 void iio_device_register_trigger_consumer(struct iio_dev *indio_dev)
 {
 	indio_dev->groups[indio_dev->groupcounter++] =
diff --git a/include/linux/iio/trigger.h b/include/linux/iio/trigger.h
index 4f1154f..ea08302 100644
--- a/include/linux/iio/trigger.h
+++ b/include/linux/iio/trigger.h
@@ -170,6 +170,8 @@ void iio_trigger_free(struct iio_trigger *trig);
  */
 bool iio_trigger_using_own(struct iio_dev *indio_dev);
 
+int iio_trigger_validate_own_device(struct iio_trigger *trig,
+				     struct iio_dev *indio_dev);
 
 #else
 struct iio_trigger;
-- 
2.1.4