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

[Dirk Behme]

On 04.03.2013 15:16, Dirk Behme wrote:
> 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)
> 

Any comments on this?

Many thanks

Dirk