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ep93xx timer: Fix possible overflow in usecs_to_ticks()

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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>
This commit is contained in:
Matthias Kaehlcke 2010-03-09 22:13:20 +01:00 • committed by trix
parent daa989b472
commit 7e67fb5bf2
1 changed files with 4 additions and 12 deletions
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16
cpu/arm920t/ep93xx/timer.c
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@ -36,7 +36,7 @@
#define TIMER_CLKSEL (1 << 3) #define TIMER_CLKSEL (1 << 3)
#define TIMER_ENABLE (1 << 7) #define TIMER_ENABLE (1 << 7)
#define TIMER_FREQ 508469 #define TIMER_FREQ 508469 /* ticks / second */
#define TIMER_MAX_VAL 0xFFFFFFFF #define TIMER_MAX_VAL 0xFFFFFFFF
static struct ep93xx_timer 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; 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; unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ;
do_div(ticks, 1000 * 1000);
if (usecs >= 1000) {
ticks = usecs / 1000;
ticks *= TIMER_FREQ;
ticks /= 1000;
} else {
ticks = usecs * TIMER_FREQ;
ticks /= (1000 * 1000);
}
return ticks; return ticks;
} }