[PATCH 1/3] staging:iio: Make write_event_value callback optional

[Lars-Peter Clausen]

Some devices have fixed thresholds which can not be modified so make the
write_event_value callback optional, so the drivers for these devices do not
have to implement a boilerplate no-op callback.

Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
Acked-by: Jonathan Cameron <jic23 at cam.ac.uk>
---
 drivers/staging/iio/industrialio-core.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/staging/iio/industrialio-core.c b/drivers/staging/iio/industrialio-core.c
index cfa4fcb..d2eea07 100644
--- a/drivers/staging/iio/industrialio-core.c
+++ b/drivers/staging/iio/industrialio-core.c
@@ -782,6 +782,9 @@ static ssize_t iio_ev_value_store(struct device *dev,
 	unsigned long val;
 	int ret;
 
+	if (!indio_dev->info->write_event_value)
+		return -EINVAL;
+
 	ret = strict_strtoul(buf, 10, &val);
 	if (ret)
 		return ret;
-- 
1.7.7