From: Matthias Kaehlcke <matthias@kaehlcke.net>
Date: Tue, 9 Mar 2010 21:13:20 +0000 (+0100)
Subject: ep93xx timer: Fix possible overflow in usecs_to_ticks()
X-Git-Tag: v2010.09-rc1~1^2~19^2~18^2~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=39ecbfcce0c7bda0fba37e4dfca520927513f4ca;p=platform%2Fkernel%2Fu-boot.git

ep93xx timer: Fix possible overflow in usecs_to_ticks()

ep93xx timer: Use 64-bit values in usecs_to_ticks() in order to avoid
overflows in intermediate values

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
---

diff --git a/cpu/arm920t/ep93xx/timer.c b/cpu/arm920t/ep93xx/timer.c
index b1a01a0..bc4ec8f 100644
--- a/cpu/arm920t/ep93xx/timer.c
+++ b/cpu/arm920t/ep93xx/timer.c
@@ -36,7 +36,7 @@
 #define TIMER_CLKSEL	(1 << 3)
 #define TIMER_ENABLE	(1 << 7)
 
-#define TIMER_FREQ			508469
+#define TIMER_FREQ			508469		/* ticks / second */
 #define TIMER_MAX_VAL			0xFFFFFFFF
 
 static struct ep93xx_timer
@@ -53,18 +53,10 @@ static inline unsigned long clk_to_systicks(unsigned long long clk_ticks)
 	return (unsigned long)sys_ticks;
 }
 
-static inline unsigned long usecs_to_ticks(unsigned long usecs)
+static inline unsigned long long usecs_to_ticks(unsigned long usecs)
 {
-	unsigned long ticks;
-
-	if (usecs >= 1000) {
-		ticks = usecs / 1000;
-		ticks *= TIMER_FREQ;
-		ticks /= 1000;
-	} else {
-		ticks = usecs * TIMER_FREQ;
-		ticks /= (1000 * 1000);
-	}
+	unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ;
+	do_div(ticks, 1000 * 1000);
 
 	return ticks;
 }