[U-Boot] [PATCH] imx-common: timer: fix 32-bit overflow

[Dirk Behme]

From: Knut Wohlrab <knut.wohlrab at de.bosch.com>

The i.MX6 common timer uses the 32-bit variable tbl (time base lower)
to record the overflow of the 32-bit counter. I.e. if the counter
overflows, the variable tbl does overflow, too.

To capture this overflow, use the variable tbu (time base upper), too.
Return the combined value of tbl and tbu.

lastinc is unused then, remove it.

Signed-off-by: Knut Wohlrab <knut.wohlrab at de.bosch.com>
Signed-off-by: Dirk Behme <dirk.behme at de.bosch.com>
---
Note: This replaces the patch
      http://patchwork.ozlabs.org/patch/224646/

 arch/arm/imx-common/timer.c |   26 +++++++-------------------
 1 file changed, 7 insertions(+), 19 deletions(-)

Index: freescale-u-boot-imx.git/arch/arm/imx-common/timer.c
===================================================================
--- freescale-u-boot-imx.git.orig/arch/arm/imx-common/timer.c
+++ freescale-u-boot-imx.git/arch/arm/imx-common/timer.c
@@ -48,9 +48,6 @@ static struct mxc_gpt *cur_gpt = (struct
 
 DECLARE_GLOBAL_DATA_PTR;
 
-#define timestamp (gd->arch.tbl)
-#define lastinc (gd->arch.lastinc)
-
 static inline unsigned long long tick_to_time(unsigned long long tick)
 {
 	tick *= CONFIG_SYS_HZ;
@@ -70,7 +67,6 @@ static inline unsigned long long us_to_t
 int timer_init(void)
 {
 	int i;
-	ulong val;
 
 	/* setup GP Timer 1 */
 	__raw_writel(GPTCR_SWR, &cur_gpt->control);
@@ -85,9 +81,8 @@ int timer_init(void)
 	i = __raw_readl(&cur_gpt->control);
 	__raw_writel(i | GPTCR_CLKSOURCE_32 | GPTCR_TEN, &cur_gpt->control);
 
-	val = __raw_readl(&cur_gpt->counter);
-	lastinc = val / (MXC_CLK32 / CONFIG_SYS_HZ);
-	timestamp = 0;
+	gd->arch.tbl = __raw_readl(&cur_gpt->counter);
+	gd->arch.tbu = 0;
 
 	return 0;
 }
@@ -96,18 +91,11 @@ unsigned long long get_ticks(void)
 {
 	ulong now = __raw_readl(&cur_gpt->counter); /* current tick value */
 
-	if (now >= lastinc) {
-		/*
-		 * normal mode (non roll)
-		 * move stamp forward with absolut diff ticks
-		 */
-		timestamp += (now - lastinc);
-	} else {
-		/* we have rollover of incrementer */
-		timestamp += (0xFFFFFFFF - lastinc) + now;
-	}
-	lastinc = now;
-	return timestamp;
+	/* increment tbu if tbl has rolled over */
+	if (now < gd->arch.tbl)
+		gd->arch.tbu++;
+	gd->arch.tbl = now;
+	return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl;
 }
 
 ulong get_timer_masked(void)