time: More core infrastructure for timespec64

Helper and conversion functions for timespec64.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

3 files changed, 118 insertions, 0 deletions

diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index 538c283714e1..da6b680c252b 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -83,6 +83,12 @@ static inline ktime_t timespec_to_ktime(struct timespec ts)
         return ktime_set(ts.tv_sec, ts.tv_nsec);
 }
 
+/* convert a timespec64 to ktime_t format: */
+static inline ktime_t timespec64_to_ktime(struct timespec64 ts)
+{
+        return ktime_set(ts.tv_sec, ts.tv_nsec);
+}
+
 /* convert a timeval to ktime_t format: */
 static inline ktime_t timeval_to_ktime(struct timeval tv)
 {
@@ -92,6 +98,9 @@ static inline ktime_t timeval_to_ktime(struct timeval tv)
 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
 #define ktime_to_timespec(kt)           ns_to_timespec((kt).tv64)
 
+/* Map the ktime_t to timespec conversion to ns_to_timespec function */
+#define ktime_to_timespec64(kt)         ns_to_timespec64((kt).tv64)
+
 /* Map the ktime_t to timeval conversion to ns_to_timeval function */
 #define ktime_to_timeval(kt)            ns_to_timeval((kt).tv64)
 
@@ -213,6 +222,25 @@ static inline __must_check bool ktime_to_timespec_cond(const ktime_t kt,
         }
 }
 
+/**
+ * ktime_to_timespec64_cond - convert a ktime_t variable to timespec64
+ *                          format only if the variable contains data
+ * @kt:         the ktime_t variable to convert
+ * @ts:         the timespec variable to store the result in
+ *
+ * Return: %true if there was a successful conversion, %false if kt was 0.
+ */
+static inline __must_check bool ktime_to_timespec64_cond(const ktime_t kt,
+                                                       struct timespec64 *ts)
+{
+        if (kt.tv64) {
+                *ts = ktime_to_timespec64(kt);
+                return true;
+        } else {
+                return false;
+        }
+}
+
 /*
  * The resolution of the clocks. The resolution value is returned in
  * the clock_getres() system call to give application programmers an
diff --git a/include/linux/time64.h b/include/linux/time64.h
index e7b499e1cd79..a3831478d9cf 100644
--- a/include/linux/time64.h
+++ b/include/linux/time64.h
@@ -33,6 +33,16 @@ struct timespec64 {
 
 #if __BITS_PER_LONG == 64
 
+static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
+{
+        return ts64;
+}
+
+static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
+{
+        return ts;
+}
+
 # define timespec64_equal               timespec_equal
 # define timespec64_compare             timespec_compare
 # define set_normalized_timespec64      set_normalized_timespec
@@ -47,6 +57,24 @@ struct timespec64 {
 
 #else
 
+static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
+{
+        struct timespec ret;
+
+        ret.tv_sec = (time_t)ts64.tv_sec;
+        ret.tv_nsec = ts64.tv_nsec;
+        return ret;
+}
+
+static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
+{
+        struct timespec64 ret;
+
+        ret.tv_sec = ts.tv_sec;
+        ret.tv_nsec = ts.tv_nsec;
+        return ret;
+}
+
 static inline int timespec64_equal(const struct timespec64 *a,
                                    const struct timespec64 *b)
 {
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 7c7964c33ae7..e8121a67fd74 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -420,6 +420,68 @@ struct timeval ns_to_timeval(const s64 nsec)
 }
 EXPORT_SYMBOL(ns_to_timeval);
 
+#if BITS_PER_LONG == 32
+/**
+ * set_normalized_timespec - set timespec sec and nsec parts and normalize
+ *
+ * @ts:         pointer to timespec variable to be set
+ * @sec:        seconds to set
+ * @nsec:       nanoseconds to set
+ *
+ * Set seconds and nanoseconds field of a timespec variable and
+ * normalize to the timespec storage format
+ *
+ * Note: The tv_nsec part is always in the range of
+ *      0 <= tv_nsec < NSEC_PER_SEC
+ * For negative values only the tv_sec field is negative !
+ */
+void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
+{
+        while (nsec >= NSEC_PER_SEC) {
+                /*
+                 * The following asm() prevents the compiler from
+                 * optimising this loop into a modulo operation. See
+                 * also __iter_div_u64_rem() in include/linux/time.h
+                 */
+                asm("" : "+rm"(nsec));
+                nsec -= NSEC_PER_SEC;
+                ++sec;
+        }
+        while (nsec < 0) {
+                asm("" : "+rm"(nsec));
+                nsec += NSEC_PER_SEC;
+                --sec;
+        }
+        ts->tv_sec = sec;
+        ts->tv_nsec = nsec;
+}
+EXPORT_SYMBOL(set_normalized_timespec64);
+
+/**
+ * ns_to_timespec64 - Convert nanoseconds to timespec64
+ * @nsec:       the nanoseconds value to be converted
+ *
+ * Returns the timespec64 representation of the nsec parameter.
+ */
+struct timespec64 ns_to_timespec64(const s64 nsec)
+{
+        struct timespec64 ts;
+        s32 rem;
+
+        if (!nsec)
+                return (struct timespec64) {0, 0};
+
+        ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
+        if (unlikely(rem < 0)) {
+                ts.tv_sec--;
+                rem += NSEC_PER_SEC;
+        }
+        ts.tv_nsec = rem;
+
+        return ts;
+}
+EXPORT_SYMBOL(ns_to_timespec64);
+#endif
 /*
  * When we convert to jiffies then we interpret incoming values
  * the following way: