> Signed-off-by: David Howells <dhowells@redhat.com>
> ---
>
> arch/mn10300/kernel/time.c | 52 +++++++++++++++++++++++++++++++++++---------
> 1 files changed, 41 insertions(+), 11 deletions(-)
>
>
> diff --git a/arch/mn10300/kernel/time.c b/arch/mn10300/kernel/time.c
> index babb7c2..e460658 100644
> --- a/arch/mn10300/kernel/time.c
> +++ b/arch/mn10300/kernel/time.c
> @@ -1,6 +1,6 @@
> /* MN10300 Low level time management
> *
> - * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
> + * Copyright (C) 2007-2008 Red Hat, Inc. All Rights Reserved.
> * Written by David Howells (
dhowells@redhat.com)
> * - Derived from arch/i386/kernel/time.c
> *
> @@ -16,6 +16,7 @@
> #include <linux/init.h>
> #include <linux/smp.h>
> #include <linux/profile.h>
> +#include <linux/cnt32_to_63.h>
> #include <asm/irq.h>
> #include <asm/div64.h>
> #include <asm/processor.h>
> @@ -40,27 +41,54 @@ static struct irqaction timer_irq = {
> .name = "timer",
> };
>
> +static unsigned long sched_clock_multiplier;
> +
> /*
> * scheduler clock - returns current time in nanosec units.
> */
> unsigned long long sched_clock(void)
> {
> union {
> - unsigned long long l;
> - u32 w[2];
> - } quot;
> + unsigned long long ll;
> + unsigned l[2];
> + } tsc64, result;
> + unsigned long tsc, tmp;
> + unsigned product[3]; /* 96-bit intermediate value */
> +
> + /* read the TSC value
> + */
> + tsc = 0 - get_cycles(); /* get_cycles() counts down */
>
> - quot.w[0] = mn10300_last_tsc - get_cycles();
> - quot.w[1] = 1000000000;
> + /* expand to 64-bits.
> + * - sched_clock() must be called once a minute or better or the
> + * following will go horribly wrong - see cnt32_to_63()
> + */
> + tsc64.ll = cnt32_to_63(tsc) & 0x7fffffffffffffffULL;
>
> - asm("mulu %2,%3,%0,%1"
> - : "=r"(quot.w[1]), "=r"(quot.w[0])
> - : "0"(quot.w[1]), "1"(quot.w[0])
> + /* scale the 64-bit TSC value to a nanosecond value via a 96-bit
> + * intermediate
> + */
> + asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */
> + "mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */
> + "add %3,%1 \n"
> + "addc 0,%2 \n" /* result in %2:%1:%0 */
> + : "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp)
> + : "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier)
> : "cc");
>
> - do_div(quot.l, MN10300_TSCCLK);
> + result.l[0] = product[1] << 16 | product[0] >> 16;
> + result.l[1] = product[2] << 16 | product[1] >> 16;
>
> - return quot.l;
> + return result.ll;
> +}
> +
> +/*
> + * initialise the scheduler clock
> + */
> +static void __init mn10300_sched_clock_init(void)
> +{
> + sched_clock_multiplier =
> + __muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK);
> }
>
> /*
> @@ -128,4 +156,6 @@ void __init time_init(void)
> /* start the watchdog timer */
> watchdog_go();
> #endif
> +
> + mn10300_sched_clock_init();
> }
>
