[kvm-unit-tests PATCH v2 2/4] lib: s390x: add CPU timer functions to time.h

[Nico Boehr <nrb@linux.ibm.com>]

Upcoming changes will make use of the CPU timer, so add a convenience
function to set the CPU timer.

Since shifts for both CPU timer and TOD clock are the same, introduce a
new define TIMING_S390_SHIFT_US. The respective shifts for CPU timer and
TOD clock reference it, so the semantic difference between the two
defines is kept.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 lib/s390x/asm/time.h | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/s390x/asm/time.h b/lib/s390x/asm/time.h
index 7652a151e87a..9ae364afb8a3 100644
--- a/lib/s390x/asm/time.h
+++ b/lib/s390x/asm/time.h
@@ -11,9 +11,13 @@
 #ifndef _ASMS390X_TIME_H_
 #define _ASMS390X_TIME_H_
 
-#define STCK_SHIFT_US	(63 - 51)
+#define TIMING_S390_SHIFT_US	(63 - 51)
+
+#define STCK_SHIFT_US	TIMING_S390_SHIFT_US
 #define STCK_MAX	((1UL << 52) - 1)
 
+#define CPU_TIMER_SHIFT_US	TIMING_S390_SHIFT_US
+
 static inline uint64_t get_clock_us(void)
 {
 	uint64_t clk;
@@ -45,4 +49,14 @@ static inline void mdelay(unsigned long ms)
 	udelay(ms * 1000);
 }
 
+static inline void cpu_timer_set(int64_t timeout_ms)
+{
+	int64_t timer_value = (timeout_ms * 1000) << CPU_TIMER_SHIFT_US;
+	asm volatile (
+		"spt %[timer_value]\n"
+		:
+		: [timer_value] "Q" (timer_value)
+	);
+}
+
 #endif
-- 
2.36.1