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lib/time.c cleanups

Browse source 
As I initially suspected overflow in time handling, I took a detailed
look at lib/time.c. This adds comments about units being used, reduces
amount of type casting being done, and makes __udelay() always wait at
least one tick. (Current code could do no delaying at all for short
delays).

Signed-off-by: Pavel Machek <pavel@denx.de>
This commit is contained in:
Pavel Machek 2014-07-13 13:14:27 +02:00 • committed by Tom Rini
parent 288afdc9b9
commit fccacd3b4c
1 changed files with 10 additions and 8 deletions
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18
lib/time.c
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@ -15,12 +15,13 @@
#endif #endif
#ifndef CONFIG_WD_PERIOD #ifndef CONFIG_WD_PERIOD
# define CONFIG_WD_PERIOD (10 * 1000 * 1000) /* 10 seconds default*/ # define CONFIG_WD_PERIOD (10 * 1000 * 1000) /* 10 seconds default */
#endif #endif
DECLARE_GLOBAL_DATA_PTR; DECLARE_GLOBAL_DATA_PTR;
#ifdef CONFIG_SYS_TIMER_RATE #ifdef CONFIG_SYS_TIMER_RATE
/* Returns tick rate in ticks per second */
ulong notrace get_tbclk(void) ulong notrace get_tbclk(void)
{ {
return CONFIG_SYS_TIMER_RATE; return CONFIG_SYS_TIMER_RATE;
@ -51,9 +52,10 @@ unsigned long long __weak notrace get_ticks(void)
return ((unsigned long long)gd->timebase_h << 32) | gd->timebase_l; return ((unsigned long long)gd->timebase_h << 32) | gd->timebase_l;
} }
static unsigned long long notrace tick_to_time(uint64_t tick) /* Returns time in milliseconds */
static unsigned long long notrace tick_to_time(unsigned long long tick)
{ {
unsigned int div = get_tbclk(); ulong div = get_tbclk();
tick *= CONFIG_SYS_HZ; tick *= CONFIG_SYS_HZ;
do_div(tick, div); do_div(tick, div);
@ -65,6 +67,7 @@ int __weak timer_init(void)
return 0; return 0;
} }
/* Returns time in milliseconds */
ulong __weak get_timer(ulong base) ulong __weak get_timer(ulong base)
{ {
return tick_to_time(get_ticks()) - base; return tick_to_time(get_ticks()) - base;
@ -74,9 +77,10 @@ unsigned long __weak notrace timer_get_us(void)
{ {
return tick_to_time(get_ticks() * 1000); return tick_to_time(get_ticks() * 1000);
} }
static unsigned long long usec_to_tick(unsigned long usec) static unsigned long long usec_to_tick(unsigned long usec)
{ {
uint64_t tick = usec; unsigned long long tick = usec;
tick *= get_tbclk(); tick *= get_tbclk();
do_div(tick, 1000000); do_div(tick, 1000000);
return tick; return tick;
@ -85,12 +89,10 @@ static unsigned long long usec_to_tick(unsigned long usec)
void __weak __udelay(unsigned long usec) void __weak __udelay(unsigned long usec)
{ {
unsigned long long tmp; unsigned long long tmp;
ulong tmo;
tmo = usec_to_tick(usec); tmp = get_ticks() + usec_to_tick(usec); /* get current timestamp */
tmp = get_ticks() + tmo; /* get current timestamp */
while (get_ticks() < tmp) /* loop till event */ while (get_ticks() < tmp+1) /* loop till event */
/*NOP*/; /*NOP*/;
} }