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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-09-22 14:30:50 +0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-09-27 12:25:02 +0400
commit40d3e0f4942ec12c4521fe1b2a2b774164cd2c80 (patch)
tree2c1fb0c4f3e298a2dcf4d8ddb32b4b1577408833 /include/linux
parent6cfa6279edbffa921b7d8c9519bfd83a24ba508e (diff)
downloadlinux-40d3e0f4942ec12c4521fe1b2a2b774164cd2c80.tar.xz
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>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/clk.h43
1 files changed, 43 insertions, 0 deletions
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 1d37f42ac294..7213b52b2c0e 100644
--- a/include/linux/clk.h
+++ b/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;
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.