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[S390] ETR support.

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This patch adds support for clock synchronization to an external time
reference (ETR). The external time reference sends an oscillator
signal and a synchronization signal every 2^20 microseconds to keep
the TOD clocks of all connected servers in sync. For availability
two ETR units can be connected to a machine. If the clock deviates
for more than the sync-check tolerance all cpus get a machine check
that indicates that the clock is out of sync. For the lovely details
how to get the clock back in sync see the code below.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2007-02-05 21:18:19 +01:00
parent c1821c2e97
commit d54853ef8c
13 changed files with 1488 additions and 109 deletions
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8
arch/s390/kernel/vtime.c
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@ -524,16 +524,15 @@ EXPORT_SYMBOL(del_virt_timer);
void init_cpu_vtimer(void)
{
struct vtimer_queue *vt_list;
unsigned long cr0;
/* kick the virtual timer */
S390_lowcore.exit_timer = VTIMER_MAX_SLICE;
S390_lowcore.last_update_timer = VTIMER_MAX_SLICE;
asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));
asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));
__ctl_store(cr0, 0, 0);
cr0 |= 0x400;
__ctl_load(cr0, 0, 0);
/* enable cpu timer interrupts */
__ctl_set_bit(0,10);
vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());
INIT_LIST_HEAD(&vt_list->list);
@ -572,6 +571,7 @@ void __init vtime_init(void)
if (register_idle_notifier(&vtimer_idle_nb))
panic("Couldn't register idle notifier");
/* Enable cpu timer interrupts on the boot cpu. */
init_cpu_vtimer();
}