clk: provide prepare/unprepare functions

As discussed previously, there's the need on some platforms to run some parts of clk_enable() in contexts which can schedule. The solution which was agreed upon was to provide clk_prepare() and clk_unprepare() to contain this parts, while clk_enable() and clk_disable() perform the atomic part. This patch provides a common definition for clk_prepare() and clk_unprepare() in linux/clk.h, and provides an upgrade path for existing implementation and drivers: drivers can start using clk_prepare() and clk_unprepare() once this patch is merged without having to wait for platform support. Platforms can then start to provide these additional functions. Eventually, HAVE_CLK_PREPARE will be removed from the kernel, and everyone will have to provide these new APIs. Acked-by: Saravana Kannan <skannan@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

clk: provide prepare/unprepare functions
As discussed previously, there's the need on some platforms to run some parts of clk_enable() in contexts which can schedule. The solution which was agreed upon was to provide clk_prepare() and clk_unprepare() to contain this parts, while clk_enable() and clk_disable() perform the atomic part. This patch provides a common definition for clk_prepare() and clk_unprepare() in linux/clk.h, and provides an upgrade path for existing implementation and drivers: drivers can start using clk_prepare() and clk_unprepare() once this patch is merged without having to wait for platform support. Platforms can then start to provide these additional functions. Eventually, HAVE_CLK_PREPARE will be removed from the kernel, and everyone will have to provide these new APIs. Acked-by: Saravana Kannan <skannan@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King
1 parent 6cfa6279ed
Showing 1 changed file with 43 additions and 0 deletions Side-by-side Diff
include/linux/clk.h
@@ -11,6 +11,8 @@
 #ifndef __LINUX_CLK_H
 #define __LINUX_CLK_H
  
+#include <linux/kernel.h>
+
 struct device;
  
 /*
  
@@ -41,11 +43,31 @@
 struct clk *clk_get(struct device *dev, const char *id);
  
 /**
+ * clk_prepare - prepare a clock source
+ * @clk: clock source
+ *
+ * This prepares the clock source for use.
+ *
+ * Must not be called from within atomic context.
+ */
+#ifdef CONFIG_HAVE_CLK_PREPARE
+int clk_prepare(struct clk *clk);
+#else
+static inline int clk_prepare(struct clk *clk)
+{
+	might_sleep();
+	return 0;
+}
+#endif
+
+/**
  * clk_enable - inform the system when the clock source should be running.
  * @clk: clock source
  *
  * If the clock can not be enabled/disabled, this should return success.
  *
+ * May be called from atomic contexts.
+ *
  * Returns success (0) or negative errno.
  */
 int clk_enable(struct clk *clk);
  
@@ -57,12 +79,33 @@
  * Inform the system that a clock source is no longer required by
  * a driver and may be shut down.
  *
+ * May be called from atomic contexts.
+ *
  * Implementation detail: if the clock source is shared between
  * multiple drivers, clk_enable() calls must be balanced by the
  * same number of clk_disable() calls for the clock source to be
  * disabled.
  */
 void clk_disable(struct clk *clk);
+
+
+/**
+ * clk_unprepare - undo preparation of a clock source
+ * @clk: clock source
+ *
+ * This undoes a previously prepared clock.  The caller must balance
+ * the number of prepare and unprepare calls.
+ *
+ * Must not be called from within atomic context.
+ */
+#ifdef CONFIG_HAVE_CLK_PREPARE
+void clk_unprepare(struct clk *clk);
+#else
+static inline void clk_unprepare(struct clk *clk)
+{
+	might_sleep();
+}
+#endif
  
 /**
  * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
...	...	@@ -11,6 +11,8 @@
11	11	#ifndef __LINUX_CLK_H
12	12	#define __LINUX_CLK_H
13	13
	14	+#include <linux/kernel.h>
	15	+
14	16	struct device;
15	17
16	18	/*
17	19
...	...	@@ -41,11 +43,31 @@
41	43	struct clk clk_get(struct device dev, const char *id);
42	44
43	45	/**
	46	+ * clk_prepare - prepare a clock source
	47	+ * @clk: clock source
	48	+ *
	49	+ * This prepares the clock source for use.
	50	+ *
	51	+ * Must not be called from within atomic context.
	52	+ */
	53	+#ifdef CONFIG_HAVE_CLK_PREPARE
	54	+int clk_prepare(struct clk *clk);
	55	+#else
	56	+static inline int clk_prepare(struct clk *clk)
	57	+{
	58	+ might_sleep();
	59	+ return 0;
	60	+}
	61	+#endif
	62	+
	63	+/**
44	64	* clk_enable - inform the system when the clock source should be running.
45	65	* @clk: clock source
46	66	*
47	67	* If the clock can not be enabled/disabled, this should return success.
48	68	*
	69	+ * May be called from atomic contexts.
	70	+ *
49	71	* Returns success (0) or negative errno.
50	72	*/
51	73	int clk_enable(struct clk *clk);
52	74
...	...	@@ -57,12 +79,33 @@
57	79	* Inform the system that a clock source is no longer required by
58	80	* a driver and may be shut down.
59	81	*
	82	+ * May be called from atomic contexts.
	83	+ *
60	84	* Implementation detail: if the clock source is shared between
61	85	* multiple drivers, clk_enable() calls must be balanced by the
62	86	* same number of clk_disable() calls for the clock source to be
63	87	* disabled.
64	88	*/
65	89	void clk_disable(struct clk *clk);
	90	+
	91	+
	92	+/**
	93	+ * clk_unprepare - undo preparation of a clock source
	94	+ * @clk: clock source
	95	+ *
	96	+ * This undoes a previously prepared clock. The caller must balance
	97	+ * the number of prepare and unprepare calls.
	98	+ *
	99	+ * Must not be called from within atomic context.
	100	+ */
	101	+#ifdef CONFIG_HAVE_CLK_PREPARE
	102	+void clk_unprepare(struct clk *clk);
	103	+#else
	104	+static inline void clk_unprepare(struct clk *clk)
	105	+{
	106	+ might_sleep();
	107	+}
	108	+#endif
66	109
67	110	/**
68	111	* clk_get_rate - obtain the current clock rate (in Hz) for a clock source.