of/overlay: add of overlay notifications
This patch add of overlay notifications.
When DT overlays are being added, some drivers/subsystems
need to see device tree overlays before the changes go into
the live tree.
This is distinct from reconfig notifiers that are
post-apply or post-remove and which issue very granular
notifications without providing access to the context
of a whole overlay.
The following 4 notificatons are issued:
OF_OVERLAY_PRE_APPLY
OF_OVERLAY_POST_APPLY
OF_OVERLAY_PRE_REMOVE
OF_OVERLAY_POST_REMOVE
In the case of pre-apply notification, if the notifier
returns error, the overlay will be rejected.
This patch exports two functions for registering/unregistering
notifications:
of_overlay_notifier_register(struct notifier_block *nb)
of_overlay_notifier_unregister(struct notifier_block *nb)
The of_mutex is held during these notifications. The
notification data includes pointers to the overlay target
and the overlay:
struct of_overlay_notify_data {
struct device_node *overlay;
struct device_node *target;
};
Signed-off-by: Alan Tull <atull@opensource.altera.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Moritz Fischer <moritz.fischer@ettus.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/of.h b/include/linux/of.h
index 299aeb1..d72f010 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1266,6 +1266,18 @@ static inline bool of_device_is_system_power_controller(const struct device_node
* Overlay support
*/
+enum of_overlay_notify_action {
+ OF_OVERLAY_PRE_APPLY,
+ OF_OVERLAY_POST_APPLY,
+ OF_OVERLAY_PRE_REMOVE,
+ OF_OVERLAY_POST_REMOVE,
+};
+
+struct of_overlay_notify_data {
+ struct device_node *overlay;
+ struct device_node *target;
+};
+
#ifdef CONFIG_OF_OVERLAY
/* ID based overlays; the API for external users */
@@ -1273,6 +1285,9 @@ int of_overlay_create(struct device_node *tree);
int of_overlay_destroy(int id);
int of_overlay_destroy_all(void);
+int of_overlay_notifier_register(struct notifier_block *nb);
+int of_overlay_notifier_unregister(struct notifier_block *nb);
+
#else
static inline int of_overlay_create(struct device_node *tree)
@@ -1290,6 +1305,16 @@ static inline int of_overlay_destroy_all(void)
return -ENOTSUPP;
}
+static inline int of_overlay_notifier_register(struct notifier_block *nb)
+{
+ return 0;
+}
+
+static inline int of_overlay_notifier_unregister(struct notifier_block *nb)
+{
+ return 0;
+}
+
#endif
#endif /* _LINUX_OF_H */