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Diffstat (limited to 'arch/s390/kernel/time.c')
-rw-r--r--arch/s390/kernel/time.c77
1 files changed, 51 insertions, 26 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index f72d41068dc..6ded50dfa75 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -52,9 +52,6 @@
#define USECS_PER_JIFFY ((unsigned long) 1000000/HZ)
#define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
-/* The value of the TOD clock for 1.1.1970. */
-#define TOD_UNIX_EPOCH 0x7d91048bca000000ULL
-
/*
* Create a small time difference between the timer interrupts
* on the different cpus to avoid lock contention.
@@ -63,9 +60,10 @@
#define TICK_SIZE tick
+u64 sched_clock_base_cc = -1; /* Force to data section. */
+
static ext_int_info_t ext_int_info_cc;
static ext_int_info_t ext_int_etr_cc;
-static u64 sched_clock_base_cc;
static DEFINE_PER_CPU(struct clock_event_device, comparators);
@@ -195,22 +193,12 @@ static void timing_alert_interrupt(__u16 code)
static void etr_reset(void);
static void stp_reset(void);
-/*
- * Get the TOD clock running.
- */
-static u64 __init reset_tod_clock(void)
+unsigned long read_persistent_clock(void)
{
- u64 time;
-
- etr_reset();
- stp_reset();
- if (store_clock(&time) == 0)
- return time;
- /* TOD clock not running. Set the clock to Unix Epoch. */
- if (set_clock(TOD_UNIX_EPOCH) != 0 || store_clock(&time) != 0)
- panic("TOD clock not operational.");
+ struct timespec ts;
- return TOD_UNIX_EPOCH;
+ tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, &ts);
+ return ts.tv_sec;
}
static cycle_t read_tod_clock(void)
@@ -265,12 +253,13 @@ void update_vsyscall_tz(void)
*/
void __init time_init(void)
{
- sched_clock_base_cc = reset_tod_clock();
+ struct timespec ts;
+ unsigned long flags;
+ cycle_t now;
- /* set xtime */
- tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &xtime);
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
+ /* Reset time synchronization interfaces. */
+ etr_reset();
+ stp_reset();
/* request the clock comparator external interrupt */
if (register_early_external_interrupt(0x1004,
@@ -278,17 +267,38 @@ void __init time_init(void)
&ext_int_info_cc) != 0)
panic("Couldn't request external interrupt 0x1004");
- if (clocksource_register(&clocksource_tod) != 0)
- panic("Could not register TOD clock source");
-
/* request the timing alert external interrupt */
if (register_early_external_interrupt(0x1406,
timing_alert_interrupt,
&ext_int_etr_cc) != 0)
panic("Couldn't request external interrupt 0x1406");
+ if (clocksource_register(&clocksource_tod) != 0)
+ 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.
+ */
+ write_seqlock_irqsave(&xtime_lock, flags);
+ now = get_clock();
+ tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);
+ clocksource_tod.cycle_last = now;
+ clocksource_tod.raw_time = xtime;
+ 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);
+
/* Enable TOD clock interrupts on the boot cpu. */
init_cpu_timer();
+
/* Enable cpu timer interrupts on the boot cpu. */
vtime_init();
}
@@ -1423,6 +1433,7 @@ static void *stp_page;
static void stp_work_fn(struct work_struct *work);
static DEFINE_MUTEX(stp_work_mutex);
static DECLARE_WORK(stp_work, stp_work_fn);
+static struct timer_list stp_timer;
static int __init early_parse_stp(char *p)
{
@@ -1454,10 +1465,16 @@ static void __init stp_reset(void)
}
}
+static void stp_timeout(unsigned long dummy)
+{
+ queue_work(time_sync_wq, &stp_work);
+}
+
static int __init stp_init(void)
{
if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
return 0;
+ setup_timer(&stp_timer, stp_timeout, 0UL);
time_init_wq();
if (!stp_online)
return 0;
@@ -1565,6 +1582,7 @@ static void stp_work_fn(struct work_struct *work)
if (!stp_online) {
chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000);
+ del_timer_sync(&stp_timer);
goto out_unlock;
}
@@ -1586,6 +1604,13 @@ static void stp_work_fn(struct work_struct *work)
stop_machine(stp_sync_clock, &stp_sync, &cpu_online_map);
put_online_cpus();
+ if (!check_sync_clock())
+ /*
+ * There is a usable clock but the synchonization failed.
+ * Retry after a second.
+ */
+ mod_timer(&stp_timer, jiffies + HZ);
+
out_unlock:
mutex_unlock(&stp_work_mutex);
}