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authorMike Turquette <mturquette@linaro.org>2012-03-15 23:11:19 -0700
committerArnd Bergmann <arnd@arndb.de>2012-03-16 20:35:01 +0000
commitb2476490ef11134b65544d8f062cff96c53e941b (patch)
tree35e341ae635a5608f6bef748d174d1dd5dcf8f9d /include/linux/clk.h
parent69fe8a8e92ae6877167f222838bd0c92b35c7d72 (diff)
clk: introduce the common clock framework
The common clock framework defines a common struct clk useful across most platforms as well as an implementation of the clk api that drivers can use safely for managing clocks. The net result is consolidation of many different struct clk definitions and platform-specific clock framework implementations. This patch introduces the common struct clk, struct clk_ops and an implementation of the well-known clock api in include/clk/clk.h. Platforms may define their own hardware-specific clock structure and their own clock operation callbacks, so long as it wraps an instance of struct clk_hw. See Documentation/clk.txt for more details. This patch is based on the work of Jeremy Kerr, which in turn was based on the work of Ben Herrenschmidt. Signed-off-by: Mike Turquette <mturquette@linaro.org> Signed-off-by: Mike Turquette <mturquette@ti.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Rob Herring <rob.herring <at> calxeda.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Jeremy Kerr <jeremy.kerr@canonical.com> Cc: Arnd Bergman <arnd.bergmann@linaro.org> Cc: Paul Walmsley <paul@pwsan.com> Cc: Shawn Guo <shawn.guo@freescale.com> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Richard Zhao <richard.zhao@linaro.org> Cc: Saravana Kannan <skannan@codeaurora.org> Cc: Magnus Damm <magnus.damm@gmail.com> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Amit Kucheria <amit.kucheria@linaro.org> Cc: Deepak Saxena <dsaxena@linaro.org> Cc: Grant Likely <grant.likely@secretlab.ca> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'include/linux/clk.h')
-rw-r--r--include/linux/clk.h68
1 files changed, 63 insertions, 5 deletions
diff --git a/include/linux/clk.h b/include/linux/clk.h
index b9d46fa154b..b0252726df6 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.