From 852db46d55e85b475a72e665ca08d3317769ceef Mon Sep 17 00:00:00 2001 From: John Stultz Date: Tue, 13 Jul 2010 17:56:28 -0700 Subject: [PATCH] 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: John Stultz LKML-Reference: <1279068988-21864-12-git-send-email-johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner --- include/linux/clocksource.h | 11 +++++++++++ kernel/time/clocksource.c | 39 +++++++++++++++++++++++++++---------- 2 files changed, 40 insertions(+), 10 deletions(-) diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 21677d99a161..c37b21ad5a3b 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -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) diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index c543d21b4e54..c18d7efa1b4b 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -638,6 +638,32 @@ static void clocksource_enqueue(struct clocksource *cs) */ #define MAX_UPDATE_LENGTH 5 /* Seconds */ +/** + * __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 + * + * This should only be called from the clocksource->enable() method. + * + * This *SHOULD NOT* be called directly! Please use the + * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions. + */ +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 + * MAX_UPDATE_LENGTH. But for now this just gets the + * register interface working properly. + */ + clocks_calc_mult_shift(&cs->mult, &cs->shift, 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 @@ -652,17 +678,10 @@ static void clocksource_enqueue(struct clocksource *cs) int __clocksource_register_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 - * MAX_UPDATE_LENGTH. But for now this just gets the - * register interface working properly. - */ - clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, - NSEC_PER_SEC/scale, - MAX_UPDATE_LENGTH*scale); - cs->max_idle_ns = clocksource_max_deferment(cs); + /* 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();