On 6/15/20 11:31 AM, Pierre Morel wrote:
> The hardware gives us a good definition of the microsecond,
> let's keep this information and let the routine accessing
> the hardware keep all the information and return microseconds.
> 
> Calculate delays in microseconds and take care about wrapping
> around zero.
> 
> Define values with macros and use inlines to keep the
> milliseconds interface.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>

Small nit below.


Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> ---
>  lib/s390x/asm/time.h | 29 +++++++++++++++++++++++++++--
>  1 file changed, 27 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/s390x/asm/time.h b/lib/s390x/asm/time.h
> index 1791380..7f1d891 100644
> --- a/lib/s390x/asm/time.h
> +++ b/lib/s390x/asm/time.h
> @@ -13,14 +13,39 @@
>  #ifndef ASM_S390X_TIME_H
>  #define ASM_S390X_TIME_H
>  
> -static inline uint64_t get_clock_ms(void)
> +#define STCK_SHIFT_US	(63 - 51)
> +#define STCK_MAX	((1UL << 52) - 1)
> +
> +static inline uint64_t get_clock_us(void)
>  {
>  	uint64_t clk;
>  
>  	asm volatile(" stck %0 " : : "Q"(clk) : "memory");
>  
>  	/* Bit 51 is incrememented each microsecond */
> -	return (clk >> (63 - 51)) / 1000;
> +	return clk >> STCK_SHIFT_US;
> +}
> +
> +static inline void udelay(unsigned long us)
> +{
> +	unsigned long startclk = get_clock_us();
> +	unsigned long c;
> +
> +	do {
> +		c = get_clock_us();
> +		if (c < startclk)
> +			c += STCK_MAX;
> +	} while (c < startclk + us);
> +}
> +
> +static inline void mdelay(unsigned long ms)
> +{
> +	udelay(ms * 1000);
> +}
> +
> +static inline uint64_t get_clock_ms(void)
> +{
> +	return get_clock_us() / 1000;
>  }

Why don't you put that below to the get_clock_us()?

>  
>  #endif
>