s390/time: LPAR offset handling

It is possible to specify a user offset for the TOD clock, e.g. +2 hours.
The TOD clock will carry this offset even if the clock is synchronized
with STP. This makes the time stamps acquired with get_sync_clock()
useless as another LPAR migth use a different TOD offset.

Use the PTFF instrution to get the TOD epoch difference and subtract
it from the TOD clock value to get a physical timestamp. As the epoch
difference contains the sync check delta as well the LPAR offset value
to the physical clock needs to be refreshed after each clock
synchronization.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index 920db0a2496b..0f34db4238da 100644
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -52,6 +52,11 @@ static inline void store_clock_comparator(__u64 *time)
 
 void clock_comparator_work(void);
 
+void __init ptff_init(void);
+
+extern unsigned char ptff_function_mask[16];
+extern unsigned long lpar_offset;
+
 /* Function codes for the ptff instruction. */
 #define PTFF_QAF	0x00	/* query available functions */
 #define PTFF_QTO	0x01	/* query tod offset */
@@ -69,6 +74,14 @@ struct ptff_qto {
 	unsigned long long tod_epoch_difference;
 } __packed;
 
+static inline int ptff_query(unsigned int nr)
+{
+	unsigned char *ptr;
+
+	ptr = ptff_function_mask + (nr >> 3);
+	return (*ptr & (0x80 >> (nr & 7))) != 0;
+}
+
 static inline int ptff(void *ptff_block, size_t len, unsigned int func)
 {
 	typedef struct { char _[len]; } addrtype;
@@ -138,7 +151,7 @@ static inline cycles_t get_cycles(void)
 	return (cycles_t) get_tod_clock() >> 2;
 }
 
-int get_sync_clock(unsigned long long *clock);
+int get_phys_clock(unsigned long long *clock);
 void init_cpu_timer(void);
 unsigned long long monotonic_clock(void);