[S390] ETR support.
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>
diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index bc5beaa..acf93db 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -125,14 +125,12 @@
* Make sure that the i/o interrupt did not "overtake"
* the last HZ timer interrupt.
*/
- account_ticks();
+ account_ticks(S390_lowcore.int_clock);
kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
index = ext_hash(code);
for (p = ext_int_hash[index]; p; p = p->next) {
- if (likely(p->code == code)) {
- if (likely(p->handler))
- p->handler(code);
- }
+ if (likely(p->code == code))
+ p->handler(code);
}
irq_exit();
set_irq_regs(old_regs);