[PATCH 38/40] ARM: orion: convert sched_clock() to use new infrastructure

[Nicolas Pitre]

On Fri, 17 Dec 2010, Russell King - ARM Linux wrote:

> Convert orion platforms to use the new sched_clock() infrastructure for
> extending 32bit counters to full 64-bit nanoseconds.
> 
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>

Acked-by: Nicolas Pitre <nico at fluxnic.net>

> ---
>  arch/arm/Kconfig           |    1 +
>  arch/arm/plat-orion/time.c |   44 +++++++++-----------------------------------
>  2 files changed, 10 insertions(+), 35 deletions(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 726279f..92e8c01 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -997,6 +997,7 @@ config PLAT_IOP
>  
>  config PLAT_ORION
>  	bool
> +	select HAVE_SCHED_CLOCK
>  
>  config PLAT_PXA
>  	bool
> diff --git a/arch/arm/plat-orion/time.c b/arch/arm/plat-orion/time.c
> index 123f96f..c3da247 100644
> --- a/arch/arm/plat-orion/time.c
> +++ b/arch/arm/plat-orion/time.c
> @@ -13,11 +13,11 @@
>  
>  #include <linux/kernel.h>
>  #include <linux/sched.h>
> -#include <linux/cnt32_to_63.h>
>  #include <linux/timer.h>
>  #include <linux/clockchips.h>
>  #include <linux/interrupt.h>
>  #include <linux/irq.h>
> +#include <asm/sched_clock.h>
>  #include <asm/mach/time.h>
>  #include <mach/bridge-regs.h>
>  #include <mach/hardware.h>
> @@ -44,52 +44,26 @@ static u32 ticks_per_jiffy;
>  
>  /*
>   * Orion's sched_clock implementation. It has a resolution of
> - * at least 7.5ns (133MHz TCLK) and a maximum value of 834 days.
> - *
> - * Because the hardware timer period is quite short (21 secs if
> - * 200MHz TCLK) and because cnt32_to_63() needs to be called at
> - * least once per half period to work properly, a kernel timer is
> - * set up to ensure this requirement is always met.
> + * at least 7.5ns (133MHz TCLK).
>   */
> -#define TCLK2NS_SCALE_FACTOR 8
> -
> -static unsigned long tclk2ns_scale;
> +static DEFINE_CLOCK_DATA(cd);
>  
>  unsigned long long notrace sched_clock(void)
>  {
> -	unsigned long long v = cnt32_to_63(0xffffffff - readl(TIMER0_VAL));
> -	return (v * tclk2ns_scale) >> TCLK2NS_SCALE_FACTOR;
> +	u32 cyc = 0xffffffff - readl(TIMER0_VAL);
> +	return cyc_to_sched_clock(&cd, cyc, (u32)~0);
>  }
>  
> -static struct timer_list cnt32_to_63_keepwarm_timer;
>  
> -static void cnt32_to_63_keepwarm(unsigned long data)
> +static void notrace orion_update_sched_clock(void)
>  {
> -	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> -	(void) sched_clock();
> +	u32 cyc = 0xffffffff - readl(TIMER0_VAL);
> +	update_sched_clock(&cd, cyc, (u32)~0);
>  }
>  
>  static void __init setup_sched_clock(unsigned long tclk)
>  {
> -	unsigned long long v;
> -	unsigned long data;
> -
> -	v = NSEC_PER_SEC;
> -	v <<= TCLK2NS_SCALE_FACTOR;
> -	v += tclk/2;
> -	do_div(v, tclk);
> -	/*
> -	 * We want an even value to automatically clear the top bit
> -	 * returned by cnt32_to_63() without an additional run time
> -	 * instruction. So if the LSB is 1 then round it up.
> -	 */
> -	if (v & 1)
> -		v++;
> -	tclk2ns_scale = v;
> -
> -	data = (0xffffffffUL / tclk / 2 - 2) * HZ;
> -	setup_timer(&cnt32_to_63_keepwarm_timer, cnt32_to_63_keepwarm, data);
> -	mod_timer(&cnt32_to_63_keepwarm_timer, round_jiffies(jiffies + data));
> +	init_sched_clock(&cd, orion_update_sched_clock, 32, tclk);
>  }
>  
>  /*
> -- 
> 1.6.2.5
>