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clk: provide prepare/unprepare functions

PATCH New Russell King - ARM Linux 2 participants 2 messages Sep 27, 2011 – Oct 27, 2011

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Common clk Clk API
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Russell King - ARM Linux

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#0 lore raw

PATCH 1/9 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 <[email protected]>
Signed-off-by Russell King <[email protected]>
---
 include/linux/clk.h |   43 +++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 43 insertions(+), 0 deletions(-)
include/linux/clk.h +43 -0
index 1d37f42..7213b52 100644
@@ -11,6 +11,8 @@
 #ifndef __LINUX_CLK_H
 #define __LINUX_CLK_H
 
+#include <linux/kernel.h>
+
 struct device;
 
 /*

@@ -41,11 +43,31 @@ struct clk;
 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);

@@ -57,6 +79,8 @@ int clk_enable(struct clk *clk);
  * 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

@@ -64,6 +88,25 @@ int clk_enable(struct clk *clk);
  */
 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.
  *		  This is only valid once the clock source has been enabled.
Signature · 1 line
1.7.4.4
#1 lore raw

PATCH 1/1 clk: add definition of HAVE_CLK_PREPARE in Kconfig

From: Domenico Andreoli <[email protected]>

Add definition of HAVE_CLK_PREPARE in Kconfig otherwise it is not selected when needed.

Signed-off-by Domenico Andreoli <[email protected]>
---
 drivers/clk/Kconfig |    3 +++
 1 file changed, 3 insertions(+)
drivers/clk/Kconfig +3 -0
Index: b/drivers/clk/Kconfig
===================================================================
@@ -5,3 +5,6 @@ config CLKDEV_LOOKUP
 
 config HAVE_MACH_CLKDEV
 	bool
+
+config HAVE_CLK_PREPARE
+	bool