timekeeping: Increase granularity of read_persistent_clock()
The persistent clock of some architectures (e.g. s390) have a
better granularity than seconds. To reduce the delta between the
host clock and the guest clock in a virtualized system change the
read_persistent_clock function to return a struct timespec.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
LKML-Reference: <20090814134811.013873340@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 5d465b2..bf67dcb 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -178,7 +178,7 @@
}
/* not static: needed by APM */
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
unsigned long retval, flags;
@@ -186,7 +186,8 @@
retval = get_wallclock();
spin_unlock_irqrestore(&rtc_lock, flags);
- return retval;
+ ts->tv_sec = retval;
+ ts->tv_nsec = 0;
}
int update_persistent_clock(struct timespec now)