linux-kernel - Re: [PATCH] Add clocksource_register

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Message-ID: <alpine.LFD.2.00.1005071735260.3401@localhost.localdomain>
Date:	Fri, 7 May 2010 17:44:57 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	John Stultz <johnstul@...ibm.com>
cc:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Add clocksource_register_hz/khz interface

On Wed, 5 May 2010, John Stultz wrote:

> Hey Thomas,
> 	I updated the patch docs and made the calls EXPORT_SYMBOL_GPL.
> However the need for both khz and hz is due to high freq clocksources
> like the TSC who's cycles/sec are close to the upper bound of a u32.

Come on. It's not that hard :)

int clocksource_register_freq(struct clocksource *cs, u32 scale, u32 freq)
{
	clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
			       NSEC_PER_SEC / scale, MAX_UPDATE_LENGTH * scale);

	....
}

static inline int clocksource_register_hz(struct clocksource *cs, u32 freq)
{
	clocksource_regiser_freq(cs, 1, freq);
}

static inline int clocksource_register_khz(struct clocksource *cs, u32 freq)
{
	clocksource_regiser_freq(cs, 1000, freq);
}
 
Thanks,

	tglx
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