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>

1 files changed, 11 insertions, 4 deletions

diff --git a/arch/mips/sibyte/swarm/setup.c b/arch/mips/sibyte/swarm/setup.c
index 672e45d495a9..623ffc933c4c 100644
--- a/arch/mips/sibyte/swarm/setup.c
+++ b/arch/mips/sibyte/swarm/setup.c
@@ -87,19 +87,26 @@ enum swarm_rtc_type {
 
 enum swarm_rtc_type swarm_rtc_type;
 
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
 {
+        unsigned long sec;
+
         switch (swarm_rtc_type) {
         case RTC_XICOR:
-                return xicor_get_time();
+                sec = xicor_get_time();
+                break;
 
         case RTC_M4LT81:
-                return m41t81_get_time();
+                sec = m41t81_get_time();
+                break;
 
         case RTC_NONE:
         default:
-                return mktime(2000, 1, 1, 0, 0, 0);
+                sec = mktime(2000, 1, 1, 0, 0, 0);
+                break;
         }
+        ts->tv_sec = sec;
+        tv->tv_nsec = 0;
 }
 
 int rtc_mips_set_time(unsigned long sec)