From ea686f52e45b3df2938866d3f5a98bb2556dfe2b Mon Sep 17 00:00:00 2001
From: Peter Pearse <peter.pearse@arm.com>
Date: Fri, 1 Feb 2008 16:50:24 +0000
Subject: [PATCH] Fix timer overflow in DaVinci Signed-off-by: Dirk Behme
<dirk.behme@gmail.com>
---
cpu/arm926ejs/davinci/timer.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/cpu/arm926ejs/davinci/timer.c b/cpu/arm926ejs/davinci/timer.c
index c6b1dda51f..4a1a54dcf1 100644
--- a/cpu/arm926ejs/davinci/timer.c
+++ b/cpu/arm926ejs/davinci/timer.c
@@ -61,6 +61,11 @@ davinci_timer *timer = (davinci_timer *)CFG_TIMERBASE;
#define TIMER_LOAD_VAL (CFG_HZ_CLOCK / CFG_HZ)
#define READ_TIMER timer->tim34
+/* Timer runs with CFG_HZ_CLOCK, currently 27MHz. To avoid wrap
+ around of timestamp already after min ~159s, divide it, e.g. by 16.
+ timestamp will then wrap around all min ~42min */
+#define DIV(x) ((x) >> 4)
+
static ulong timestamp;
static ulong lastinc;
@@ -101,20 +106,20 @@ void udelay(unsigned long usec)
void reset_timer_masked(void)
{
- lastinc = READ_TIMER;
+ lastinc = DIV(READ_TIMER);
timestamp = 0;
}
ulong get_timer_raw(void)
{
- ulong now = READ_TIMER;
+ ulong now = DIV(READ_TIMER);
if (now >= lastinc) {
/* normal mode */
timestamp += now - lastinc;
} else {
/* overflow ... */
- timestamp += now + TIMER_LOAD_VAL - lastinc;
+ timestamp += now + DIV(TIMER_LOAD_VAL) - lastinc;
}
lastinc = now;
return timestamp;
@@ -122,7 +127,7 @@ ulong get_timer_raw(void)
ulong get_timer_masked(void)
{
- return(get_timer_raw() / TIMER_LOAD_VAL);
+ return(get_timer_raw() / DIV(TIMER_LOAD_VAL));
}
void udelay_masked(unsigned long usec)
--
2.39.5