Add notifier framework

This is loosely based on the Linux notifier framework, but
stripped down to the bare minimum.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/include/notifier.h b/include/notifier.h
new file mode 100644
index 0000000000..878b17e078
--- /dev/null
+++ b/include/notifier.h
@@ -0,0 +1,35 @@
+#ifndef __NOTIFIER_H
+#define __NOTIFIER_H
+
+/*
+ * Notifer chains loosely based on the according Linux framework
+ */
+
+struct notifier_block {
+	int (*notifier_call)(struct notifier_block *, unsigned long, void *);
+	struct list_head list;
+};
+
+struct notifier_head {
+	struct list_head blocks;
+};
+
+int notifier_chain_register(struct notifier_head *nh, struct notifier_block *n);
+
+int notifier_call_chain(struct notifier_head *nh, unsigned long val, void *v);
+
+/*
+ * Register a function which is called upon changes of
+ * clock frequencies in the system.
+ */
+int clock_register_client(struct notifier_block *nb);
+int clock_unregister_client(struct notifier_block *nb);
+int clock_notifier_call_chain(void);
+
+#define NOTIFIER_HEAD(name)					\
+	struct notifier_head name = {				\
+		.blocks = LIST_HEAD_INIT((name).blocks),	\
+	};
+
+#endif /* __NOTIFIER_H */
+