timekeeping: Move TAI managment into timekeeping core from ntp

Currently NTP manages the TAI offset. Since there's plans for a
CLOCK_TAI clockid, push the TAI management into the timekeeping
core.

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>

2 files changed, 54 insertions, 8 deletions

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 072bb066bb7d..59e2749be0fa 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -53,9 +53,6 @@ static int			time_state = TIME_OK;
 /* clock status bits:                                                   */
 static int                      time_status = STA_UNSYNC;
 
-/* TAI offset (secs):                                                   */
-static long                     time_tai;
-
 /* time adjustment (nsecs):                                             */
 static s64                      time_offset;
 
@@ -415,7 +412,6 @@ int second_overflow(unsigned long secs)
                 else if (secs % 86400 == 0) {
                         leap = -1;
                         time_state = TIME_OOP;
-                        time_tai++;
                         printk(KERN_NOTICE
                                 "Clock: inserting leap second 23:59:60 UTC\n");
                 }
@@ -425,7 +421,6 @@ int second_overflow(unsigned long secs)
                         time_state = TIME_OK;
                 else if ((secs + 1) % 86400 == 0) {
                         leap = 1;
-                        time_tai--;
                         time_state = TIME_WAIT;
                         printk(KERN_NOTICE
                                 "Clock: deleting leap second 23:59:59 UTC\n");
@@ -579,7 +574,9 @@ static inline void process_adj_status(struct timex *txc, struct timespec *ts)
  * Called with ntp_lock held, so we can access and modify
  * all the global NTP state:
  */
-static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts)
+static inline void process_adjtimex_modes(struct timex *txc,
+                                                struct timespec *ts,
+                                                s32 *time_tai)
 {
         if (txc->modes & ADJ_STATUS)
                 process_adj_status(txc, ts);
@@ -613,7 +610,7 @@ static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts
         }
 
         if (txc->modes & ADJ_TAI && txc->constant > 0)
-                time_tai = txc->constant;
+                *time_tai = txc->constant;
 
         if (txc->modes & ADJ_OFFSET)
                 ntp_update_offset(txc->offset);
@@ -632,6 +629,7 @@ static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts
 int do_adjtimex(struct timex *txc)
 {
         struct timespec ts;
+        u32 time_tai, orig_tai;
         int result;
 
         /* Validate the data before disabling interrupts */
@@ -671,6 +669,7 @@ int do_adjtimex(struct timex *txc)
         }
 
         getnstimeofday(&ts);
+        orig_tai = time_tai = timekeeping_get_tai_offset();
 
         raw_spin_lock_irq(&ntp_lock);
 
@@ -687,7 +686,7 @@ int do_adjtimex(struct timex *txc)
 
                 /* If there are input parameters, then process them: */
                 if (txc->modes)
-                        process_adjtimex_modes(txc, &ts);
+                        process_adjtimex_modes(txc, &ts, &time_tai);
 
                 txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
                                   NTP_SCALE_SHIFT);
@@ -716,6 +715,9 @@ int do_adjtimex(struct timex *txc)
 
         raw_spin_unlock_irq(&ntp_lock);
 
+        if (time_tai != orig_tai)
+                timekeeping_set_tai_offset(time_tai);
+
         txc->time.tv_sec = ts.tv_sec;
         txc->time.tv_usec = ts.tv_nsec;
         if (!(time_status & STA_NANO))
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0355f125d585..937098aab498 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -513,6 +513,48 @@ error: /* even if we error out, we forwarded the time, so call update */
 }
 EXPORT_SYMBOL(timekeeping_inject_offset);
 
+
+/**
+ * timekeeping_get_tai_offset - Returns current TAI offset from UTC
+ *
+ */
+s32 timekeeping_get_tai_offset(void)
+{
+        struct timekeeper *tk = &timekeeper;
+        unsigned int seq;
+        s32 ret;
+
+        do {
+                seq = read_seqbegin(&tk->lock);
+                ret = tk->tai_offset;
+        } while (read_seqretry(&tk->lock, seq));
+
+        return ret;
+}
+
+/**
+ * __timekeeping_set_tai_offset - Lock free worker function
+ *
+ */
+void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
+{
+        tk->tai_offset = tai_offset;
+}
+
+/**
+ * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
+ *
+ */
+void timekeeping_set_tai_offset(s32 tai_offset)
+{
+        struct timekeeper *tk = &timekeeper;
+        unsigned long flags;
+
+        write_seqlock_irqsave(&tk->lock, flags);
+        __timekeeping_set_tai_offset(tk, tai_offset);
+        write_sequnlock_irqrestore(&tk->lock, flags);
+}
+
 /**
  * change_clocksource - Swaps clocksources if a new one is available
  *
@@ -1143,6 +1185,8 @@ static inline void accumulate_nsecs_to_secs(struct timekeeper *tk)
                         tk_set_wall_to_mono(tk,
                                 timespec_sub(tk->wall_to_monotonic, ts));
 
+                        __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
+
                         clock_was_set_delayed();
                 }
         }