Re: [PATCH v2 2/3] riscv: timer: add timer_get_boot_us for BOOTSTAGE

[Leo Liang <ycliang@andestech.com>]

Hi Chanho,

On Mon, Aug 28, 2023 at 06:49:37PM +0900, Chanho Park wrote:
> timer_get_boot_us function is required to record the boot stages as
> us-based timestamp.
> 
> Signed-off-by: Chanho Park <chanho61.park@samsung.com>
> ---
>  drivers/timer/riscv_timer.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/timer/riscv_timer.c b/drivers/timer/riscv_timer.c
> index 3627ed79b819..6cb589fcdc45 100644
> --- a/drivers/timer/riscv_timer.c
> +++ b/drivers/timer/riscv_timer.c
> @@ -11,6 +11,7 @@
>   */
>  
>  #include <common.h>
> +#include <div64.h>
>  #include <dm.h>
>  #include <errno.h>
>  #include <timer.h>
> @@ -50,6 +51,26 @@ u64 notrace timer_early_get_count(void)
>  }
>  #endif
>  
> +#if CONFIG_IS_ENABLED(RISCV_SMODE) && CONFIG_IS_ENABLED(BOOTSTAGE)
> +ulong timer_get_boot_us(void)
> +{
> +	int ret;
> +	u64 ticks = 0;
> +	u32 rate;
> +
> +	ret = dm_timer_init();
> +	if (!ret) {
> +		rate = timer_get_rate(gd->timer);
> +		timer_get_count(gd->timer, &ticks);
> +	} else {
> +		rate = RISCV_SMODE_TIMER_FREQ;
> +		ticks = riscv_timer_get_count(NULL);
> +	}
> +
> +	return lldiv(ticks * 1000, (rate / 1000));

Could you elaborate a little how this formula is derived?

Best regards,
Leo

> +}
> +#endif
> +
>  static int riscv_timer_probe(struct udevice *dev)
>  {
>  	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> -- 
> 2.39.2
>