[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/include/asm-s390/timex.h b/include/asm-s390/timex.h
index 9ee5d80..5cbd55c 100644
--- a/include/asm-s390/timex.h
+++ b/include/asm-s390/timex.h
@@ -11,6 +11,41 @@
#ifndef _ASM_S390_TIMEX_H
#define _ASM_S390_TIMEX_H
+/* Inline functions for clock register access. */
+static inline int set_clock(__u64 time)
+{
+ int cc;
+
+ asm volatile(
+ " sck 0(%2)\n"
+ " ipm %0\n"
+ " srl %0,28\n"
+ : "=d" (cc) : "m" (time), "a" (&time) : "cc");
+ return cc;
+}
+
+static inline int store_clock(__u64 *time)
+{
+ int cc;
+
+ asm volatile(
+ " stck 0(%2)\n"
+ " ipm %0\n"
+ " srl %0,28\n"
+ : "=d" (cc), "=m" (*time) : "a" (time) : "cc");
+ return cc;
+}
+
+static inline void set_clock_comparator(__u64 time)
+{
+ asm volatile("sckc 0(%1)" : : "m" (time), "a" (&time));
+}
+
+static inline void store_clock_comparator(__u64 *time)
+{
+ asm volatile("stckc 0(%1)" : "=m" (*time) : "a" (time));
+}
+
#define CLOCK_TICK_RATE 1193180 /* Underlying HZ */
typedef unsigned long long cycles_t;
@@ -32,6 +67,7 @@
return (cycles_t) get_clock() >> 2;
}
+int get_sync_clock(unsigned long long *clock);
void init_cpu_timer(void);
#endif