On Nov 24, 2011, at 12:07 AM, Anton Blanchard wrote:
> We can use clockevents_calc_mult_shift instead of doing all
> the work ourselves.
>
> Signed-off-by: Anton Blanchard <an...@samba.org>
> ---
>
> Index: linux-build/arch/powerpc/kernel/time.c
> ===================================================================
> --- linux-build.orig/arch/powerpc/kernel/time.c 2011-11-17
> 10:11:49.035001617 +1100
> +++ linux-build/arch/powerpc/kernel/time.c 2011-11-17 10:11:51.175038860
> +1100
> @@ -112,8 +112,6 @@ static void decrementer_set_mode(enum cl
> static struct clock_event_device decrementer_clockevent = {
> .name = "decrementer",
> .rating = 200,
> - .shift = 0, /* To be filled in */
> - .mult = 0, /* To be filled in */
> .irq = 0,
> .set_next_event = decrementer_set_next_event,
> .set_mode = decrementer_set_mode,
> @@ -913,31 +911,6 @@ static void decrementer_set_mode(enum cl
> decrementer_set_next_event(DECREMENTER_MAX, dev);
> }
>
> -static inline uint64_t div_sc64(unsigned long ticks, unsigned long nsec,
> - int shift)
> -{
> - uint64_t tmp = ((uint64_t)ticks) << shift;
> -
> - do_div(tmp, nsec);
> - return tmp;
> -}
> -
> -static void __init setup_clockevent_multiplier(unsigned long hz)
> -{
> - u64 mult, shift = 32;
> -
> - while (1) {
> - mult = div_sc64(hz, NSEC_PER_SEC, shift);
> - if (mult && (mult >> 32UL) == 0UL)
> - break;
> -
> - shift--;
> - }
> -
> - decrementer_clockevent.shift = shift;
> - decrementer_clockevent.mult = mult;
> -}
> -
> static void register_decrementer_clockevent(int cpu)
> {
> struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;
> @@ -955,7 +928,8 @@ static void __init init_decrementer_cloc
> {
> int cpu = smp_processor_id();
>
> - setup_clockevent_multiplier(ppc_tb_freq);
> + clockevents_calc_mult_shift(&decrementer_clockevent, ppc_tb_freq, 4);
> +
Where's this magic 4 come from?
> decrementer_clockevent.max_delta_ns =
> clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
> decrementer_clockevent.min_delta_ns =
>
>
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