timekeeping: Add CLOCK_TAI clockid

This add a CLOCK_TAI clockid and the needed accessors.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

4 files changed, 43 insertions, 4 deletions

diff --git a/include/linux/time.h b/include/linux/time.h
index 47210a175e78..22d81b3c955b 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -183,6 +183,7 @@ extern u64 timekeeping_max_deferment(void);
 extern int timekeeping_inject_offset(struct timespec *ts);
 extern s32 timekeeping_get_tai_offset(void);
 extern void timekeeping_set_tai_offset(s32 tai_offset);
+extern void timekeeping_clocktai(struct timespec *ts);
 
 struct tms;
 extern void do_sys_times(struct tms *);
diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h
index 0d3c0edc3eda..e75e1b6ff27f 100644
--- a/include/uapi/linux/time.h
+++ b/include/uapi/linux/time.h
@@ -54,11 +54,9 @@ struct itimerval {
 #define CLOCK_BOOTTIME                  7
 #define CLOCK_REALTIME_ALARM            8
 #define CLOCK_BOOTTIME_ALARM            9
+#define CLOCK_SGI_CYCLE                 10      /* Hardware specific */
+#define CLOCK_TAI                       11
 
-/*
- * The IDs of various hardware clocks:
- */
-#define CLOCK_SGI_CYCLE                 10
 #define MAX_CLOCKS                      16
 #define CLOCKS_MASK                     (CLOCK_REALTIME | CLOCK_MONOTONIC)
 #define CLOCKS_MONO                     CLOCK_MONOTONIC
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 6edbb2c55c22..fbfc5f1b7710 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -221,6 +221,11 @@ static int posix_get_boottime(const clockid_t which_clock, struct timespec *tp)
         return 0;
 }
 
+static int posix_get_tai(clockid_t which_clock, struct timespec *tp)
+{
+        timekeeping_clocktai(tp);
+        return 0;
+}
 
 /*
  * Initialize everything, well, just everything in Posix clocks/timers ;)
@@ -261,6 +266,10 @@ static __init int init_posix_timers(void)
                 .clock_getres   = posix_get_coarse_res,
                 .clock_get      = posix_get_monotonic_coarse,
         };
+        struct k_clock clock_tai = {
+                .clock_getres   = hrtimer_get_res,
+                .clock_get      = posix_get_tai,
+        };
         struct k_clock clock_boottime = {
                 .clock_getres   = hrtimer_get_res,
                 .clock_get      = posix_get_boottime,
@@ -278,6 +287,7 @@ static __init int init_posix_timers(void)
         posix_timers_register_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
         posix_timers_register_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
         posix_timers_register_clock(CLOCK_BOOTTIME, &clock_boottime);
+        posix_timers_register_clock(CLOCK_TAI, &clock_tai);
 
         posix_timers_cache = kmem_cache_create("posix_timers_cache",
                                         sizeof (struct k_itimer), 0, SLAB_PANIC,
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 937098aab498..8a842756572d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -379,6 +379,36 @@ void ktime_get_ts(struct timespec *ts)
 }
 EXPORT_SYMBOL_GPL(ktime_get_ts);
 
+
+/**
+ * timekeeping_clocktai - Returns the TAI time of day in a timespec
+ * @ts:         pointer to the timespec to be set
+ *
+ * Returns the time of day in a timespec.
+ */
+void timekeeping_clocktai(struct timespec *ts)
+{
+        struct timekeeper *tk = &timekeeper;
+        unsigned long seq;
+        u64 nsecs;
+
+        WARN_ON(timekeeping_suspended);
+
+        do {
+                seq = read_seqbegin(&tk->lock);
+
+                ts->tv_sec = tk->xtime_sec + tk->tai_offset;
+                nsecs = timekeeping_get_ns(tk);
+
+        } while (read_seqretry(&tk->lock, seq));
+
+        ts->tv_nsec = 0;
+        timespec_add_ns(ts, nsecs);
+
+}
+EXPORT_SYMBOL(timekeeping_clocktai);
+
+
 #ifdef CONFIG_NTP_PPS
 
 /**