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Commit 40d3e0f4 authored by Russell King's avatar Russell King
Browse files

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: default avatarSaravana Kannan <skannan@codeaurora.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 6cfa6279

include/linux/clk.h

+43 −0
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ 
#ifndef __LINUX_CLK_H

#define __LINUX_CLK_H



#include <linux/kernel.h>



struct device;



/*
@@ -40,12 +42,32 @@ 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.