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Diffstat (limited to 'cpu/arm926ejs/nomadik/timer.c')
-rw-r--r--cpu/arm926ejs/nomadik/timer.c15
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" */