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Commit 7aca0c07 authored by Alexander Kuleshov's avatar Alexander Kuleshov Committed by Thomas Gleixner
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clocksource: Introduce clocksource_freq2mult() 



The clocksource_khz2mult() and clocksource_hz2mult() share similar
code wihch calculates a mult from the given frequency. Both implementations
in differ only in value of a frequency. This patch introduces the
clocksource_freq2mult() helper with generic implementation of
mult calculation to prevent code duplication.

Signed-off-by: default avatarAlexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1456542854-22104-2-git-send-email-john.stultz@linaro.org


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 07f101d3

include/linux/clocksource.h

+19 −26
Original line number Diff line number Diff line
@@ -118,6 +118,23 @@ struct clocksource { 
/* simplify initialization of mask field */

#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)



static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)

{

	/*  freq = cyc/from

	 *  mult/2^shift  = ns/cyc

	 *  mult = ns/cyc * 2^shift

	 *  mult = from/freq * 2^shift

	 *  mult = from * 2^shift / freq

	 *  mult = (from<<shift) / freq

	 */

	u64 tmp = ((u64)from) << shift_constant;



	tmp += freq/2; /* round for do_div */

	do_div(tmp, freq);



	return (u32)tmp;

}



/**

 * clocksource_khz2mult - calculates mult from khz and shift

 * @khz:		Clocksource frequency in KHz
@@ -128,19 +145,7 @@ struct clocksource { 
 */

static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)

{

	/*  khz = cyc/(Million ns)

	 *  mult/2^shift  = ns/cyc

	 *  mult = ns/cyc * 2^shift

	 *  mult = 1Million/khz * 2^shift

	 *  mult = 1000000 * 2^shift / khz

	 *  mult = (1000000<<shift) / khz

	 */

	u64 tmp = ((u64)1000000) << shift_constant;



	tmp += khz/2; /* round for do_div */

	do_div(tmp, khz);



	return (u32)tmp;

	return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);

}



/**
@@ -154,19 +159,7 @@ static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) 
 */

static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)

{

	/*  hz = cyc/(Billion ns)

	 *  mult/2^shift  = ns/cyc

	 *  mult = ns/cyc * 2^shift

	 *  mult = 1Billion/hz * 2^shift

	 *  mult = 1000000000 * 2^shift / hz

	 *  mult = (1000000000<<shift) / hz

	 */

	u64 tmp = ((u64)1000000000) << shift_constant;



	tmp += hz/2; /* round for do_div */

	do_div(tmp, hz);



	return (u32)tmp;

	return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);

}



/**