1 files changed, 63 insertions, 5 deletions

diff --git a/include/linux/clk.h b/include/linux/clk.h
index b9d46fa154b4..b0252726df61 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -3,6 +3,7 @@
  *
  *  Copyright (C) 2004 ARM Limited.
  *  Written by Deep Blue Solutions Limited.
+ *  Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -12,18 +13,75 @@
 #define __LINUX_CLK_H
 
 #include <linux/kernel.h>
+#include <linux/notifier.h>
 
 struct device;
 
-/*
- * The base API.
+struct clk;
+
+#ifdef CONFIG_COMMON_CLK
+
+/**
+ * DOC: clk notifier callback types
+ *
+ * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
+ *     to indicate that the rate change will proceed.  Drivers must
+ *     immediately terminate any operations that will be affected by the
+ *     rate change.  Callbacks may either return NOTIFY_DONE or
+ *     NOTIFY_STOP.
+ *
+ * ABORT_RATE_CHANGE: called if the rate change failed for some reason
+ *     after PRE_RATE_CHANGE.  In this case, all registered notifiers on
+ *     the clk will be called with ABORT_RATE_CHANGE. Callbacks must
+ *     always return NOTIFY_DONE.
+ *
+ * POST_RATE_CHANGE - called after the clk rate change has successfully
+ *     completed.  Callbacks must always return NOTIFY_DONE.
+ *
  */
+#define PRE_RATE_CHANGE                 BIT(0)
+#define POST_RATE_CHANGE                BIT(1)
+#define ABORT_RATE_CHANGE               BIT(2)
 
+/**
+ * struct clk_notifier - associate a clk with a notifier
+ * @clk: struct clk * to associate the notifier with
+ * @notifier_head: a blocking_notifier_head for this clk
+ * @node: linked list pointers
+ *
+ * A list of struct clk_notifier is maintained by the notifier code.
+ * An entry is created whenever code registers the first notifier on a
+ * particular @clk.  Future notifiers on that @clk are added to the
+ * @notifier_head.
+ */
+struct clk_notifier {
+        struct clk                      *clk;
+        struct srcu_notifier_head       notifier_head;
+        struct list_head                node;
+};
 
-/*
- * struct clk - an machine class defined object / cookie.
+/**
+ * struct clk_notifier_data - rate data to pass to the notifier callback
+ * @clk: struct clk * being changed
+ * @old_rate: previous rate of this clk
+ * @new_rate: new rate of this clk
+ *
+ * For a pre-notifier, old_rate is the clk's rate before this rate
+ * change, and new_rate is what the rate will be in the future.  For a
+ * post-notifier, old_rate and new_rate are both set to the clk's
+ * current rate (this was done to optimize the implementation).
  */
-struct clk;
+struct clk_notifier_data {
+        struct clk              *clk;
+        unsigned long           old_rate;
+        unsigned long           new_rate;
+};
+
+int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
+
+int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
+
+#endif /* !CONFIG_COMMON_CLK */
 
 /**
  * clk_get - lookup and obtain a reference to a clock producer.