iio: trigger: allow immutable triggers to be assigned

There are times when an assigned trigger to a device shouldn't ever
change after intialization.

Examples of this being used is when an provider device has a trigger
that is assigned to an ADC, which uses it populate data into a callback
buffer.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

2 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 854e2dad1e0d..786952cd509f 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -483,6 +483,7 @@ struct iio_buffer_setup_ops {
  * @scan_timestamp:     [INTERN] set if any buffers have requested timestamp
  * @scan_index_timestamp:[INTERN] cache of the index to the timestamp
  * @trig:               [INTERN] current device trigger (buffer modes)
+ * @trig_readonly       [INTERN] mark the current trigger immutable
  * @pollfunc:           [DRIVER] function run on trigger being received
  * @pollfunc_event:     [DRIVER] function run on events trigger being received
  * @channels:           [DRIVER] channel specification structure table
@@ -523,6 +524,7 @@ struct iio_dev {
         bool                            scan_timestamp;
         unsigned                        scan_index_timestamp;
         struct iio_trigger              *trig;
+        bool                            trig_readonly;
         struct iio_poll_func            *pollfunc;
         struct iio_poll_func            *pollfunc_event;
 
diff --git a/include/linux/iio/trigger.h b/include/linux/iio/trigger.h
index 1c9e028e0d4a..a122bdd4076c 100644
--- a/include/linux/iio/trigger.h
+++ b/include/linux/iio/trigger.h
@@ -132,6 +132,15 @@ int iio_trigger_register(struct iio_trigger *trig_info);
 void iio_trigger_unregister(struct iio_trigger *trig_info);
 
 /**
+ * iio_trigger_set_immutable() - set an immutable trigger on destination
+ *
+ * @indio_dev - IIO device structure containing the device
+ * @trig - trigger to assign to device
+ *
+ **/
+int iio_trigger_set_immutable(struct iio_dev *indio_dev, struct iio_trigger *trig);
+
+/**
  * iio_trigger_poll() - called on a trigger occurring
  * @trig:       trigger which occurred
  *