diff options
Diffstat (limited to 'arch/s390/kernel/time.c')
-rw-r--r-- | arch/s390/kernel/time.c | 77 |
1 files changed, 51 insertions, 26 deletions
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index f72d41068dc2..6ded50dfa75a 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); } |