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authorMagnus Damm <damm@igel.co.jp>2009-04-21 12:24:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-21 13:41:47 -0700
commit4614e6adafa2c5e6c3a9c245af2807fa7bc5117a (patch)
treee4bb5eeaa252ede053abc6b3c4d15c4127ce7a32 /kernel
parent8e19608e8b5c001e4a66ce482edc474f05fb7355 (diff)
downloadlinux-4614e6adafa2c5e6c3a9c245af2807fa7bc5117a.tar.bz2
clocksource: add enable() and disable() callbacks
Add enable() and disable() callbacks for clocksources. This allows us to put unused clocksources in power save mode. The functions clocksource_enable() and clocksource_disable() wrap the callbacks and are inserted in the timekeeping code to enable before use and disable after switching to a new clocksource. Signed-off-by: Magnus Damm <damm@igel.co.jp> Acked-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/timekeeping.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 900f1b6598d1..687dff49f6e7 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -182,7 +182,7 @@ EXPORT_SYMBOL(do_settimeofday);
*/
static void change_clocksource(void)
{
- struct clocksource *new;
+ struct clocksource *new, *old;
new = clocksource_get_next();
@@ -191,11 +191,16 @@ static void change_clocksource(void)
clocksource_forward_now();
- new->raw_time = clock->raw_time;
+ if (clocksource_enable(new))
+ return;
+ new->raw_time = clock->raw_time;
+ old = clock;
clock = new;
+ clocksource_disable(old);
+
clock->cycle_last = 0;
- clock->cycle_last = clocksource_read(new);
+ clock->cycle_last = clocksource_read(clock);
clock->error = 0;
clock->xtime_nsec = 0;
clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
@@ -292,6 +297,7 @@ void __init timekeeping_init(void)
ntp_init();
clock = clocksource_get_next();
+ clocksource_enable(clock);
clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
clock->cycle_last = clocksource_read(clock);