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/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c
index d182b2f..6843224 100644
--- a/arch/m68knommu/kernel/time.c
+++ b/arch/m68knommu/kernel/time.c
@@ -72,9 +72,10 @@
return mktime(year, mon, day, hour, min, sec);;
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
- return read_rtc_mmss();
+ ts->tv_sec = read_rtc_mmss();
+ ts->tv_nsec = 0;
}
int update_persistent_clock(struct timespec now)
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c
index 463136e..02f505f 100644
--- a/arch/mips/dec/time.c
+++ b/arch/mips/dec/time.c
@@ -18,7 +18,7 @@
#include <asm/dec/ioasic.h>
#include <asm/dec/machtype.h>
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
unsigned int year, mon, day, hour, min, sec, real_year;
unsigned long flags;
@@ -53,7 +53,8 @@
year += real_year - 72 + 2000;
- return mktime(year, mon, day, hour, min, sec);
+ ts->tv_sec = mktime(year, mon, day, hour, min, sec);
+ ts->tv_nsec = 0;
}
/*
diff --git a/arch/mips/lasat/ds1603.c b/arch/mips/lasat/ds1603.c
index 52cb143..c6fd96f 100644
--- a/arch/mips/lasat/ds1603.c
+++ b/arch/mips/lasat/ds1603.c
@@ -135,7 +135,7 @@
lasat_ndelay(1000);
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
unsigned long word;
unsigned long flags;
@@ -147,7 +147,8 @@
rtc_end_op();
spin_unlock_irqrestore(&rtc_lock, flags);
- return word;
+ ts->tv_sec = word;
+ ts->tv_nsec = 0;
}
int rtc_mips_set_mmss(unsigned long time)
diff --git a/arch/mips/lasat/sysctl.c b/arch/mips/lasat/sysctl.c
index 8f88886..3f04d4c 100644
--- a/arch/mips/lasat/sysctl.c
+++ b/arch/mips/lasat/sysctl.c
@@ -92,10 +92,12 @@
int proc_dolasatrtc(ctl_table *table, int write, struct file *filp,
void *buffer, size_t *lenp, loff_t *ppos)
{
+ struct timespec ts;
int r;
if (!write) {
- rtctmp = read_persistent_clock();
+ read_persistent_clock(&ts);
+ rtctmp = ts.tv_sec;
/* check for time < 0 and set to 0 */
if (rtctmp < 0)
rtctmp = 0;
@@ -134,9 +136,11 @@
void *oldval, size_t *oldlenp,
void *newval, size_t newlen)
{
+ struct timespec ts;
int r;
- rtctmp = read_persistent_clock();
+ read_persistent_clock(&ts);
+ rtctmp = ts.tv_sec;
if (rtctmp < 0)
rtctmp = 0;
r = sysctl_intvec(table, oldval, oldlenp, newval, newlen);
diff --git a/arch/mips/lemote/lm2e/setup.c b/arch/mips/lemote/lm2e/setup.c
index ebd6cea..24b355d 100644
--- a/arch/mips/lemote/lm2e/setup.c
+++ b/arch/mips/lemote/lm2e/setup.c
@@ -54,9 +54,10 @@
mips_hpt_frequency = cpu_clock_freq / 2;
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
- return mc146818_get_cmos_time();
+ ts->tv_sec = mc146818_get_cmos_time();
+ ts->tv_nsec = 0;
}
void (*__wbflush)(void);
diff --git a/arch/mips/mti-malta/malta-time.c b/arch/mips/mti-malta/malta-time.c
index 0b97d47..3c6f190 100644
--- a/arch/mips/mti-malta/malta-time.c
+++ b/arch/mips/mti-malta/malta-time.c
@@ -100,9 +100,10 @@
return count;
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
- return mc146818_get_cmos_time();
+ ts->tv_sec = mc146818_get_cmos_time();
+ ts->tv_nsec = 0;
}
static void __init plat_perf_setup(void)
diff --git a/arch/mips/pmc-sierra/yosemite/setup.c b/arch/mips/pmc-sierra/yosemite/setup.c
index 2d3c0dc..3498ac9 100644
--- a/arch/mips/pmc-sierra/yosemite/setup.c
+++ b/arch/mips/pmc-sierra/yosemite/setup.c
@@ -70,7 +70,7 @@
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
unsigned int year, month, day, hour, min, sec;
unsigned long flags;
@@ -92,7 +92,8 @@
m48t37_base->control = 0x00;
spin_unlock_irqrestore(&rtc_lock, flags);
- return mktime(year, month, day, hour, min, sec);
+ ts->tv_sec = mktime(year, month, day, hour, min, sec);
+ ts->tv_nsec = 0;
}
int rtc_mips_set_time(unsigned long tim)
diff --git a/arch/mips/sibyte/swarm/setup.c b/arch/mips/sibyte/swarm/setup.c
index 672e45d..623ffc9 100644
--- a/arch/mips/sibyte/swarm/setup.c
+++ b/arch/mips/sibyte/swarm/setup.c
@@ -87,19 +87,26 @@
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)
diff --git a/arch/mips/sni/time.c b/arch/mips/sni/time.c
index 0d9ec1a..62df6a5 100644
--- a/arch/mips/sni/time.c
+++ b/arch/mips/sni/time.c
@@ -182,7 +182,8 @@
setup_pit_timer();
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
- return -1;
+ ts->tv_sec = -1;
+ ts->tv_nsec = 0;
}
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index eae4511..ad63f30 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -769,7 +769,7 @@
return ppc_md.set_rtc_time(&tm);
}
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
struct rtc_time tm;
static int first = 1;
@@ -787,8 +787,9 @@
if (!ppc_md.get_rtc_time)
return 0;
ppc_md.get_rtc_time(&tm);
- return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
- tm.tm_hour, tm.tm_min, tm.tm_sec);
+ ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
+ tm.tm_hour, tm.tm_min, tm.tm_sec);
+ ts->tv_nsec = 0;
}
/* clocksource code */
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index e76c2e7..a94ec48 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -182,12 +182,9 @@
static void etr_reset(void);
static void stp_reset(void);
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
- struct timespec ts;
-
- tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, &ts);
- return ts.tv_sec;
+ tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, ts);
}
static cycle_t read_tod_clock(struct clocksource *cs)
@@ -248,7 +245,6 @@
{
struct timespec ts;
unsigned long flags;
- cycle_t now;
/* Reset time synchronization interfaces. */
etr_reset();
@@ -266,20 +262,10 @@
panic("Could not register TOD clock source");
/*
- * The TOD clock is an accurate clock. The xtime should be
- * initialized in a way that the difference between TOD and
- * xtime is reasonably small. Too bad that timekeeping_init
- * sets xtime.tv_nsec to zero. In addition the clock source
- * change from the jiffies clock source to the TOD clock
- * source add another error of up to 1/HZ second. The same
- * function sets wall_to_monotonic to a value that is too
- * small for /proc/uptime to be accurate.
- * Reset xtime and wall_to_monotonic to sane values.
+ * Reset wall_to_monotonic to the initial timestamp created
+ * in head.S to get a precise value in /proc/uptime.
*/
write_seqlock_irqsave(&xtime_lock, flags);
- now = get_clock();
- tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);
- clocksource_tod.cycle_last = now;
tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);
set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);
write_sequnlock_irqrestore(&xtime_lock, flags);
diff --git a/arch/sh/kernel/time.c b/arch/sh/kernel/time.c
index 9b352a1..3f4706a 100644
--- a/arch/sh/kernel/time.c
+++ b/arch/sh/kernel/time.c
@@ -39,11 +39,9 @@
int (*rtc_sh_set_time)(const time_t) = null_rtc_set_time;
#ifdef CONFIG_GENERIC_CMOS_UPDATE
-unsigned long read_persistent_clock(void)
+void read_persistent_clock(struct timespec *ts)
{
- struct timespec tv;
- rtc_sh_get_time(&tv);
- return tv.tv_sec;
+ rtc_sh_get_time(&ts);
}
int update_persistent_clock(struct timespec now)
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)
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index 8848120..19085ff 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -59,9 +59,8 @@
void __init time_init(void)
{
- xtime.tv_nsec = 0;
- xtime.tv_sec = read_persistent_clock();
-
+ /* FIXME: xtime&wall_to_monotonic are set in timekeeping_init. */
+ read_persistent_clock(&xtime);
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);