From a25cbd045a2ffc42787d4dbcbb9c7118f5f42732 Mon Sep 17 00:00:00 2001 From: Magnus Damm Date: Fri, 1 May 2009 14:45:46 +0900 Subject: clocksource: setup mult_orig in clocksource_enable() Setup clocksource mult_orig in clocksource_enable(). Clocksource drivers can save power by using keeping the device clock disabled while the clocksource is unused. In practice this means that the enable() and disable() callbacks perform clk_enable() and clk_disable(). The enable() callback may also use clk_get_rate() to get the clock rate from the clock framework. This information can then be used to calculate the shift and mult variables. Currently the mult_orig variable is setup from mult at registration time only. This is conflicting with the above case since the clock is disabled and the mult variable is not yet calculated at the time of registration. Moving the mult_orig setup code to clocksource_enable() allows us to both handle the common case with no enable() callback and the mult-changed-after-enable() case. [ Impact: allow dynamic clock source usage ] Signed-off-by: Magnus Damm LKML-Reference: <20090501054546.8193.10688.sendpatchset@rx1.opensource.se> Signed-off-by: Thomas Gleixner --- kernel/time/clocksource.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'kernel/time') diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index ecfd7b5187e..80189f6f1c5 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -402,9 +402,6 @@ int clocksource_register(struct clocksource *c) unsigned long flags; int ret; - /* save mult_orig on registration */ - c->mult_orig = c->mult; - spin_lock_irqsave(&clocksource_lock, flags); ret = clocksource_enqueue(c); if (!ret) -- cgit v1.2.3-70-g09d2 From 7d27558c4138ac6b3684dea35c2f4379b940a7dd Mon Sep 17 00:00:00 2001 From: john stultz Date: Fri, 1 May 2009 13:10:26 -0700 Subject: timekeeping: create arch_gettimeoffset infrastructure Some arches don't supply their own clocksource. This is mainly the case in architectures that get their inter-tick times by reading the counter on their interval timer. Since these timers wrap every tick, they're not really useful as clocksources. Wrapping them to act like one is possible but not very efficient. So we provide a callout these arches can implement for use with the jiffies clocksource to provide finer then tick granular time. [ Impact: ease the migration to generic time keeping ] Signed-off-by: John Stultz Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner --- include/linux/time.h | 15 +++++++++++++++ kernel/time/timekeeping.c | 7 +++++++ 2 files changed, 22 insertions(+) (limited to 'kernel/time') diff --git a/include/linux/time.h b/include/linux/time.h index 242f62499bb..ea16c1a01d5 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -113,6 +113,21 @@ struct timespec current_kernel_time(void); #define CURRENT_TIME (current_kernel_time()) #define CURRENT_TIME_SEC ((struct timespec) { get_seconds(), 0 }) +/* Some architectures do not supply their own clocksource. + * This is mainly the case in architectures that get their + * inter-tick times by reading the counter on their interval + * timer. Since these timers wrap every tick, they're not really + * useful as clocksources. Wrapping them to act like one is possible + * but not very efficient. So we provide a callout these arches + * can implement for use with the jiffies clocksource to provide + * finer then tick granular time. + */ +#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET +extern u32 arch_gettimeoffset(void); +#else +static inline u32 arch_gettimeoffset(void) { return 0; } +#endif + extern void do_gettimeofday(struct timeval *tv); extern int do_settimeofday(struct timespec *tv); extern int do_sys_settimeofday(struct timespec *tv, struct timezone *tz); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 687dff49f6e..e97c50f8458 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -77,6 +77,10 @@ static void clocksource_forward_now(void) clock->cycle_last = cycle_now; nsec = cyc2ns(clock, cycle_delta); + + /* If arch requires, add in gettimeoffset() */ + nsec += arch_gettimeoffset(); + timespec_add_ns(&xtime, nsec); nsec = ((s64)cycle_delta * clock->mult_orig) >> clock->shift; @@ -111,6 +115,9 @@ void getnstimeofday(struct timespec *ts) /* convert to nanoseconds: */ nsecs = cyc2ns(clock, cycle_delta); + /* If arch requires, add in gettimeoffset() */ + nsecs += arch_gettimeoffset(); + } while (read_seqretry(&xtime_lock, seq)); timespec_add_ns(ts, nsecs); -- cgit v1.2.3-70-g09d2