From: Matt Ranostay <mranostay@xxxxxxxxx>
There are times when a trigger consumer shouldn't be allowed to change
triggers after intialization.
This is useful with use of callback buffers pushing ADC data back to the
trigger providers iio device.
Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
---
Changes from v1:
* use bool instead of int for trig_readonly property
drivers/iio/industrialio-trigger.c | 20 ++++++++++++++++++++
include/linux/iio/iio.h | 2 ++
include/linux/iio/trigger.h | 9 +++++++++
3 files changed, 31 insertions(+)
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 7ad82fdd3e5b..a3ae3873f998 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -119,6 +119,22 @@ void iio_trigger_unregister(struct iio_trigger *trig_info)
}
EXPORT_SYMBOL(iio_trigger_unregister);
+int iio_trigger_set_immutable(struct iio_dev *dst, struct iio_trigger *trig)
+{
+ if (!dst || !trig)
+ return -EINVAL;
+
+ mutex_lock(&dst->mlock);
+ WARN_ON(dst->trig_readonly);
+
+ dst->trig = iio_trigger_get(trig);
+ dst->trig_readonly = true;
+ mutex_unlock(&dst->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 @@ static ssize_t iio_trigger_write_current(struct device *dev,
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);
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..9e22284a4122 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
+ *
+ * @dst - destination device for trigger
+ * @trig - trigger to assign to destination
+ *
+ **/
+int iio_trigger_set_immutable(struct iio_dev *dst, struct iio_trigger *trig);
+
+/**
* iio_trigger_poll() - called on a trigger occurring
* @trig: trigger which occurred
*
--
2.7.4
--
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