# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.1082  -> 1.1083 
#	include/linux/timex.h	1.5     -> 1.6    
#	       kernel/time.c	1.12    -> 1.13   
#	      kernel/timer.c	1.53    -> 1.54   
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/05/14	davidm@tiger.hpl.hp.com	1.1083
# Add two hooks for high-precision time-interpolation.  Based on patch by
# Jes Sorensen.
# --------------------------------------------
#
diff -Nru a/include/linux/timex.h b/include/linux/timex.h
--- a/include/linux/timex.h	Thu May 15 13:42:12 2003
+++ b/include/linux/timex.h	Thu May 15 13:42:12 2003
@@ -310,6 +310,13 @@
 extern long pps_errcnt;		/* calibration errors */
 extern long pps_stbcnt;		/* stability limit exceeded */
 
+/*
+ * Call-back for high precision timer sources to snapshot every time
+ * wall_jiffies is updated.
+ */
+extern void (*update_wall_time_hook)(long adjust_nsec);
+extern void (*reset_wall_time_hook)(void);
+
 #endif /* KERNEL */
 
 #endif /* LINUX_TIMEX_H */
diff -Nru a/kernel/time.c b/kernel/time.c
--- a/kernel/time.c	Thu May 15 13:42:12 2003
+++ b/kernel/time.c	Thu May 15 13:42:12 2003
@@ -35,8 +35,6 @@
  */
 struct timezone sys_tz;
 
-extern unsigned long last_nsec_offset;
-
 #if !defined(__alpha__) && !defined(__ia64__)
 
 /*
@@ -77,9 +75,10 @@
 	if (get_user(value, tptr))
 		return -EFAULT;
 	write_seqlock_irq(&xtime_lock);
+
+	(*reset_wall_time_hook)();
 	xtime.tv_sec = value;
 	xtime.tv_nsec = 0;
-	last_nsec_offset = 0;
 	time_adjust = 0;	/* stop active adjtime() */
 	time_status |= STA_UNSYNC;
 	time_maxerror = NTP_PHASE_LIMIT;
@@ -125,7 +124,7 @@
 {
 	write_seqlock_irq(&xtime_lock);
 	xtime.tv_sec += sys_tz.tz_minuteswest * 60;
-	last_nsec_offset = 0;
+	(*update_wall_time_hook)(sys_tz.tz_minuteswest * 60 * NSEC_PER_SEC);
 	write_sequnlock_irq(&xtime_lock);
 }
 
@@ -381,7 +380,6 @@
 	txc->calcnt	   = pps_calcnt;
 	txc->errcnt	   = pps_errcnt;
 	txc->stbcnt	   = pps_stbcnt;
-	last_nsec_offset = 0;
 	write_sequnlock_irq(&xtime_lock);
 	do_gettimeofday(&txc->time);
 	return(result);
diff -Nru a/kernel/timer.c b/kernel/timer.c
--- a/kernel/timer.c	Thu May 15 13:42:12 2003
+++ b/kernel/timer.c	Thu May 15 13:42:12 2003
@@ -65,6 +65,16 @@
 
 typedef struct tvec_t_base_s tvec_base_t;
 
+/*
+ * Hooks for using external high precision timers for the system clock.
+ * On systems where the CPU clock isn't synchronized between CPUs,
+ * it is necessary to use an external source such as an RTC to obtain
+ * precision in gettimeofday().
+ */
+static void nop (void) { }
+void (*update_wall_time_hook)(long delta_nsec) = (void (*) (void)) &nop;
+void (*reset_wall_time_hook)(void) = &nop;
+
 static inline void set_running_timer(tvec_base_t *base,
 					struct timer_list *timer)
 {
@@ -451,7 +461,6 @@
  */
 struct timespec xtime __attribute__ ((aligned (16)));
 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
-unsigned long last_nsec_offset;
 
 /* Don't completely fail for HZ > 500.  */
 int tickadj = 500/HZ ? : 1;		/* microsecs */
@@ -518,6 +527,7 @@
 	if (xtime.tv_sec % 86400 == 0) {
 	    xtime.tv_sec--;
 	    wall_to_monotonic.tv_sec++;
+	    (*update_wall_time_hook)(-NSEC_PER_SEC);
 	    time_state = TIME_OOP;
 	    clock_was_set();
 	    printk(KERN_NOTICE "Clock: inserting leap second 23:59:60 UTC\n");
@@ -528,6 +538,7 @@
 	if ((xtime.tv_sec + 1) % 86400 == 0) {
 	    xtime.tv_sec++;
 	    wall_to_monotonic.tv_sec--;
+	    (*update_wall_time_hook)(NSEC_PER_SEC);
 	    time_state = TIME_WAIT;
 	    clock_was_set();
 	    printk(KERN_NOTICE "Clock: deleting leap second 23:59:59 UTC\n");
@@ -643,25 +654,7 @@
 		delta_nsec += ltemp;
 	}
 	xtime.tv_nsec += delta_nsec;
-
-	/*
-	 * The whole point of last_nsec_offset is that it can be updated atomically and
-	 * lock-free.  Thus, arches that don't have __HAVE_ARCH_CMPXCHG probably can't use
-	 * last_nsec_offset anyhow... --davidm 2003-Feb-11
-	 */
-#ifdef __HAVE_ARCH_CMPXCHG
-	if (last_nsec_offset > 0) {
-		unsigned long new, old;
-
-		do {
-			old = last_nsec_offset;
-			if (old > delta_nsec)
-				new = old - delta_nsec;
-			else
-				new = 0;
-		} while (cmpxchg(&last_nsec_offset, old, new) != old);
-	}
-#endif
+	(*update_wall_time_hook)(delta_nsec);	/* update time interpolation */
 }
 
 /*
@@ -681,6 +674,7 @@
 	if (xtime.tv_nsec >= 1000000000) {
 	    xtime.tv_nsec -= 1000000000;
 	    xtime.tv_sec++;
+	    (*update_wall_time_hook)(NSEC_PER_SEC);
 	    second_overflow();
 	}
 }