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>
This commit is contained in:
Martin Schwidefsky 2009-08-14 15:47:31 +02:00 committed by Thomas Gleixner
parent 75c5158f70
commit d4f587c67f
16 changed files with 83 additions and 74 deletions

View File

@ -72,9 +72,10 @@ static unsigned long read_rtc_mmss(void)
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)

View File

@ -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 @@ unsigned long read_persistent_clock(void)
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;
}
/*

View File

@ -135,7 +135,7 @@ static void rtc_end_op(void)
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 @@ unsigned long read_persistent_clock(void)
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)

View File

@ -92,10 +92,12 @@ static int rtctmp;
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 @@ int sysctl_lasat_rtc(ctl_table *table,
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);

View File

@ -54,9 +54,10 @@ void __init plat_time_init(void)
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);

View File

@ -100,9 +100,10 @@ static unsigned int __init estimate_cpu_frequency(void)
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)

View File

@ -70,7 +70,7 @@ void __init bus_error_init(void)
}
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 @@ unsigned long read_persistent_clock(void)
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)

View File

@ -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)

View File

@ -182,7 +182,8 @@ void __init plat_time_init(void)
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;
}

View File

@ -769,7 +769,7 @@ int update_persistent_clock(struct timespec now)
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 @@ unsigned long read_persistent_clock(void)
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,
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 */

View File

@ -182,12 +182,9 @@ static void timing_alert_interrupt(__u16 code)
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 @@ void __init time_init(void)
{
struct timespec ts;
unsigned long flags;
cycle_t now;
/* Reset time synchronization interfaces. */
etr_reset();
@ -266,20 +262,10 @@ void __init time_init(void)
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);

View File

@ -39,11 +39,9 @@ void (*rtc_sh_get_time)(struct timespec *) = null_rtc_get_time;
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)

View File

@ -178,7 +178,7 @@ static int set_rtc_mmss(unsigned long nowtime)
}
/* 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 @@ unsigned long read_persistent_clock(void)
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)

View File

@ -59,9 +59,8 @@ static struct irqaction timer_irqaction = {
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);

View File

@ -101,7 +101,7 @@ extern struct timespec xtime;
extern struct timespec wall_to_monotonic;
extern seqlock_t xtime_lock;
extern unsigned long read_persistent_clock(void);
extern void read_persistent_clock(struct timespec *ts);
extern int update_persistent_clock(struct timespec now);
extern int no_sync_cmos_clock __read_mostly;
void timekeeping_init(void);

View File

@ -154,7 +154,7 @@ __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
*/
struct timespec xtime __attribute__ ((aligned (16)));
struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
static unsigned long total_sleep_time; /* seconds */
static struct timespec total_sleep_time;
/*
* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
@ -487,17 +487,18 @@ int timekeeping_valid_for_hres(void)
}
/**
* read_persistent_clock - Return time in seconds from the persistent clock.
* read_persistent_clock - Return time from the persistent clock.
*
* Weak dummy function for arches that do not yet support it.
* Returns seconds from epoch using the battery backed persistent clock.
* Returns zero if unsupported.
* Reads the time from the battery backed persistent clock.
* Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
*
* XXX - Do be sure to remove it once all arches implement it.
*/
unsigned long __attribute__((weak)) read_persistent_clock(void)
void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
{
return 0;
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
/*
@ -507,7 +508,9 @@ void __init timekeeping_init(void)
{
struct clocksource *clock;
unsigned long flags;
unsigned long sec = read_persistent_clock();
struct timespec now;
read_persistent_clock(&now);
write_seqlock_irqsave(&xtime_lock, flags);
@ -518,19 +521,20 @@ void __init timekeeping_init(void)
clock->enable(clock);
timekeeper_setup_internals(clock);
xtime.tv_sec = sec;
xtime.tv_nsec = 0;
xtime.tv_sec = now.tv_sec;
xtime.tv_nsec = now.tv_nsec;
raw_time.tv_sec = 0;
raw_time.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
update_xtime_cache(0);
total_sleep_time = 0;
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
}
/* time in seconds when suspend began */
static unsigned long timekeeping_suspend_time;
static struct timespec timekeeping_suspend_time;
/**
* timekeeping_resume - Resumes the generic timekeeping subsystem.
@ -543,18 +547,19 @@ static unsigned long timekeeping_suspend_time;
static int timekeeping_resume(struct sys_device *dev)
{
unsigned long flags;
unsigned long now = read_persistent_clock();
struct timespec ts;
read_persistent_clock(&ts);
clocksource_resume();
write_seqlock_irqsave(&xtime_lock, flags);
if (now && (now > timekeeping_suspend_time)) {
unsigned long sleep_length = now - timekeeping_suspend_time;
xtime.tv_sec += sleep_length;
wall_to_monotonic.tv_sec -= sleep_length;
total_sleep_time += sleep_length;
if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
ts = timespec_sub(ts, timekeeping_suspend_time);
xtime = timespec_add_safe(xtime, ts);
wall_to_monotonic = timespec_sub(wall_to_monotonic, ts);
total_sleep_time = timespec_add_safe(total_sleep_time, ts);
}
update_xtime_cache(0);
/* re-base the last cycle value */
@ -577,7 +582,7 @@ static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
{
unsigned long flags;
timekeeping_suspend_time = read_persistent_clock();
read_persistent_clock(&timekeeping_suspend_time);
write_seqlock_irqsave(&xtime_lock, flags);
timekeeping_forward_now();
@ -801,9 +806,10 @@ void update_wall_time(void)
*/
void getboottime(struct timespec *ts)
{
set_normalized_timespec(ts,
- (wall_to_monotonic.tv_sec + total_sleep_time),
- wall_to_monotonic.tv_nsec);
struct timespec boottime;
boottime = timespec_add_safe(wall_to_monotonic, total_sleep_time);
set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
}
/**
@ -812,7 +818,7 @@ void getboottime(struct timespec *ts)
*/
void monotonic_to_bootbased(struct timespec *ts)
{
ts->tv_sec += total_sleep_time;
*ts = timespec_add_safe(*ts, total_sleep_time);
}
unsigned long get_seconds(void)