From 7e67fb5bf27a07d3b8d6b97c76f7195f7d68af58 Mon Sep 17 00:00:00 2001
From: Matthias Kaehlcke <matthias@kaehlcke.net>
Date: Tue, 9 Mar 2010 22:13:20 +0100
Subject: [PATCH] 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>
---
cpu/arm920t/ep93xx/timer.c | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/cpu/arm920t/ep93xx/timer.c b/cpu/arm920t/ep93xx/timer.c
index b1a01a05e9..bc4ec8fcd4 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;
}
--
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