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>
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 7ad82fd..3dde81e 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -119,6 +119,22 @@
}
EXPORT_SYMBOL(iio_trigger_unregister);
+int iio_trigger_set_immutable(struct iio_dev *indio_dev, struct iio_trigger *trig)
+{
+ if (!indio_dev || !trig)
+ return -EINVAL;
+
+ mutex_lock(&indio_dev->mlock);
+ WARN_ON(indio_dev->trig_readonly);
+
+ indio_dev->trig = iio_trigger_get(trig);
+ indio_dev->trig_readonly = true;
+ mutex_unlock(&indio_dev->mlock);
+
+ return 0;
+}
+EXPORT_SYMBOL(iio_trigger_set_immutable);
+
/* Search for trigger by name, assuming iio_trigger_list_lock held */
static struct iio_trigger *__iio_trigger_find_by_name(const char *name)
{
@@ -384,6 +400,10 @@
mutex_unlock(&indio_dev->mlock);
return -EBUSY;
}
+ if (indio_dev->trig_readonly) {
+ mutex_unlock(&indio_dev->mlock);
+ return -EPERM;
+ }
mutex_unlock(&indio_dev->mlock);
trig = iio_trigger_find_by_name(buf, len);