From 2448a5573afb56352c7601ac3ff7487e68528fc3 Mon Sep 17 00:00:00 2001
From: =?utf8?q?=E9=BB=84=E6=B6=9B?= <huangtao@rock-chips.com>
Date: Sat, 30 Jul 2011 15:56:49 +0800
Subject: [PATCH] Revert "clocksource: Provide a generic mult/shift factor
 calculation"

This reverts commit cfc80b68293040b1f06c1fb388d3bd448721aa7b.
---
 include/linux/clockchips.h  |  7 -----
 include/linux/clocksource.h | 10 -------
 kernel/time/clocksource.c   | 53 -------------------------------------
 3 files changed, 70 deletions(-)

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index b7905462043c..3a1dbba4d3ae 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -130,13 +130,6 @@ extern int clockevents_program_event(struct clock_event_device *dev,
 
 extern void clockevents_handle_noop(struct clock_event_device *dev);
 
-static inline void
-clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
-{
-	return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
-				      freq, minsec);
-}
-
 #ifdef CONFIG_GENERIC_CLOCKEVENTS
 extern void clockevents_notify(unsigned long reason, void *arg);
 #else
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 8a4a130cc196..f73bc1b68c10 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -281,16 +281,6 @@ extern void clocksource_resume(void);
 extern struct clocksource * __init __weak clocksource_default_clock(void);
 extern void clocksource_mark_unstable(struct clocksource *cs);
 
-extern void
-clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
-
-static inline void
-clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
-{
-	return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
-				      NSEC_PER_SEC, minsec);
-}
-
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 extern void
 update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult);
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 6d7c7fe5396a..bf4fe98bcba8 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -107,59 +107,6 @@ u64 timecounter_cyc2time(struct timecounter *tc,
 }
 EXPORT_SYMBOL(timecounter_cyc2time);
 
-/**
- * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
- * @mult:	pointer to mult variable
- * @shift:	pointer to shift variable
- * @from:	frequency to convert from
- * @to:		frequency to convert to
- * @minsec:	guaranteed runtime conversion range in seconds
- *
- * The function evaluates the shift/mult pair for the scaled math
- * operations of clocksources and clockevents.
- *
- * @to and @from are frequency values in HZ. For clock sources @to is
- * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
- * event @to is the counter frequency and @from is NSEC_PER_SEC.
- *
- * The @minsec conversion range argument controls the time frame in
- * seconds which must be covered by the runtime conversion with the
- * calculated mult and shift factors. This guarantees that no 64bit
- * overflow happens when the input value of the conversion is
- * multiplied with the calculated mult factor. Larger ranges may
- * reduce the conversion accuracy by chosing smaller mult and shift
- * factors.
- */
-void
-clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
-{
-	u64 tmp;
-	u32 sft, sftacc= 32;
-
-	/*
-	 * Calculate the shift factor which is limiting the conversion
-	 * range:
-	 */
-	tmp = ((u64)minsec * from) >> 32;
-	while (tmp) {
-		tmp >>=1;
-		sftacc--;
-	}
-
-	/*
-	 * Find the conversion shift/mult pair which has the best
-	 * accuracy and fits the maxsec conversion range:
-	 */
-	for (sft = 32; sft > 0; sft--) {
-		tmp = (u64) to << sft;
-		do_div(tmp, from);
-		if ((tmp >> sftacc) == 0)
-			break;
-	}
-	*mult = tmp;
-	*shift = sft;
-}
-
 /*[Clocksource internal variables]---------
  * curr_clocksource:
  *	currently selected clocksource.
-- 
2.34.1