diff options
Diffstat (limited to 'cpu/arm926ejs/nomadik/timer.c')
| -rw-r--r-- | cpu/arm926ejs/nomadik/timer.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/cpu/arm926ejs/nomadik/timer.c b/cpu/arm926ejs/nomadik/timer.c index 047b9e3..1d98ef3 100644 --- a/cpu/arm926ejs/nomadik/timer.c +++ b/cpu/arm926ejs/nomadik/timer.c @@ -34,8 +34,8 @@ #define TICKS_PER_HZ (TIMER_CLOCK / CONFIG_SYS_HZ) #define TICKS_TO_HZ(x) ((x) / TICKS_PER_HZ) -/* macro to read the 32 bit timer: since it decrements, we invert read value */ -#define READ_TIMER() (~readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0))) +/* macro to read the decrementing 32 bit timer as an increasing count */ +#define READ_TIMER() (0 - readl(CONFIG_SYS_TIMERBASE + MTU_VAL(0))) /* Configure a free-running, auto-wrap counter with no prescaler */ int timer_init(void) @@ -49,7 +49,16 @@ int timer_init(void) /* Restart counting from 0 */ void reset_timer(void) { - writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); /* Immediate effect */ + ulong val; + writel(0, CONFIG_SYS_TIMERBASE + MTU_LR(0)); + /* + * The load-register isn't really immediate: it changes on clock + * edges, so we must wait for our newly-written value to appear. + * Since we might miss reading 0, wait for any change in value. + */ + val = READ_TIMER(); + while (READ_TIMER() == val) + ; } /* Return how many HZ passed since "base" */ |