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Commit 852db46d authored by John Stultz's avatar John Stultz Committed by Thomas Gleixner
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clocksource: Add __clocksource_updatefreq_hz/khz methods 



To properly handle clocksources that change frequencies
at the clocksource->enable() point, this patch adds
a method that will update the clocksource's mult/shift and
max_idle_ns values.

Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <1279068988-21864-12-git-send-email-johnstul@us.ibm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent f12a15be

include/linux/clocksource.h

+11 −0
Original line number Diff line number Diff line
@@ -292,6 +292,8 @@ clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); 
 */

extern int

__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);

extern void

__clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq);



static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)

{
@@ -303,6 +305,15 @@ static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) 
	return __clocksource_register_scale(cs, 1000, khz);

}



static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz)

{

	__clocksource_updatefreq_scale(cs, 1, hz);

}



static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz)

{

	__clocksource_updatefreq_scale(cs, 1000, khz);

}



static inline void

clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)

kernel/time/clocksource.c

+24 −5
Original line number Diff line number Diff line
@@ -639,19 +639,18 @@ static void clocksource_enqueue(struct clocksource *cs) 
#define MAX_UPDATE_LENGTH 5 /* Seconds */



/**

 * __clocksource_register_scale - Used to install new clocksources

 * __clocksource_updatefreq_scale - Used update clocksource with new freq

 * @t:		clocksource to be registered

 * @scale:	Scale factor multiplied against freq to get clocksource hz

 * @freq:	clocksource frequency (cycles per second) divided by scale

 *

 * Returns -EBUSY if registration fails, zero otherwise.

 * This should only be called from the clocksource->enable() method.

 *

 * This *SHOULD NOT* be called directly! Please use the

 * clocksource_register_hz() or clocksource_register_khz helper functions.

 * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions.

 */

int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)

void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq)

{



	/*

	 * Ideally we want to use  some of the limits used in

	 * clocksource_max_deferment, to provide a more informed
@@ -662,7 +661,27 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) 
				      NSEC_PER_SEC/scale,

				      MAX_UPDATE_LENGTH*scale);

	cs->max_idle_ns = clocksource_max_deferment(cs);

}

EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale);



/**

 * __clocksource_register_scale - Used to install new clocksources

 * @t:		clocksource to be registered

 * @scale:	Scale factor multiplied against freq to get clocksource hz

 * @freq:	clocksource frequency (cycles per second) divided by scale

 *

 * Returns -EBUSY if registration fails, zero otherwise.

 *

 * This *SHOULD NOT* be called directly! Please use the

 * clocksource_register_hz() or clocksource_register_khz helper functions.

 */

int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)

{



	/* Intialize mult/shift and max_idle_ns */

	__clocksource_updatefreq_scale(cs, scale, freq);



	/* Add clocksource to the clcoksource list */

	mutex_lock(&clocksource_mutex);

	clocksource_enqueue(cs);

	clocksource_select();