ntp: support for TAI

This adds support for setting the TAI value (International Atomic Time).  The
value is reported back to userspace via timex (as we don't have a
ntp_gettime() syscall).

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 9 insertions, 1 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 4a856a3643bb..32c254a8ab9a 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -955,7 +955,8 @@ asmlinkage long compat_sys_adjtimex(struct compat_timex __user *utp)
                         __put_user(txc.jitcnt, &utp->jitcnt) ||
                         __put_user(txc.calcnt, &utp->calcnt) ||
                         __put_user(txc.errcnt, &utp->errcnt) ||
-                        __put_user(txc.stbcnt, &utp->stbcnt))
+                        __put_user(txc.stbcnt, &utp->stbcnt) ||
+                        __put_user(txc.tai, &utp->tai))
                 ret = -EFAULT;
 
         return ret;
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 44491de312a0..10fe17df45a0 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -35,6 +35,7 @@ static u64 tick_length, tick_length_base;
 /* TIME_ERROR prevents overwriting the CMOS clock */
 static int time_state = TIME_OK;        /* clock synchronization status */
 int time_status = STA_UNSYNC;           /* clock status bits            */
+static long time_tai;                   /* TAI offset (s)               */
 static s64 time_offset;                 /* time adjustment (ns)         */
 static long time_constant = 2;          /* pll time constant            */
 long time_maxerror = NTP_PHASE_LIMIT;   /* maximum error (us)           */
@@ -162,6 +163,7 @@ void second_overflow(void)
         case TIME_DEL:
                 if ((xtime.tv_sec + 1) % 86400 == 0) {
                         xtime.tv_sec++;
+                        time_tai--;
                         wall_to_monotonic.tv_sec--;
                         time_state = TIME_WAIT;
                         printk(KERN_NOTICE "Clock: deleting leap second "
@@ -169,6 +171,7 @@ void second_overflow(void)
                 }
                 break;
         case TIME_OOP:
+                time_tai++;
                 time_state = TIME_WAIT;
                 break;
         case TIME_WAIT:
@@ -340,6 +343,9 @@ int do_adjtimex(struct timex *txc)
                         time_constant = max(time_constant, 0l);
                 }
 
+                if (txc->modes & ADJ_TAI && txc->constant > 0)
+                        time_tai = txc->constant;
+
                 if (txc->modes & ADJ_OFFSET) {
                         if (txc->modes == ADJ_OFFSET_SINGLESHOT)
                                 /* adjtime() is independent from ntp_adjtime() */
@@ -377,6 +383,7 @@ int do_adjtimex(struct timex *txc)
         txc->precision     = 1;
         txc->tolerance     = MAXFREQ_SCALED / PPM_SCALE;
         txc->tick          = tick_usec;
+        txc->tai           = time_tai;
 
         /* PPS is not implemented, so these are zero */
         txc->ppsfreq       = 0;