On Thu, Sep 12, 2013 at 07:51:26AM +0100, Fan Rong wrote:
> Signed-off-by: Fan Rong <cin...@gmail.com>
> ---
> arch/arm/include/asm/arch_timer.h | 11 +++++++++++
> drivers/clocksource/Kconfig | 8 ++++++++
> drivers/clocksource/arm_arch_timer.c | 10 +++++++++-
> 3 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/include/asm/arch_timer.h
> b/arch/arm/include/asm/arch_timer.h
> index 5665134..24c904a 100644
> --- a/arch/arm/include/asm/arch_timer.h
> +++ b/arch/arm/include/asm/arch_timer.h
> @@ -87,6 +87,17 @@ static inline u64 arch_counter_get_cntvct(void)
> return cval;
> }
>
> +static inline u64 arch_counter_get_cntpct(void)
> +{
> + u64 cval;
> +
> + isb();
> + asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (cval));
> + return cval;
> +}
> +
> +
> +
> static inline void arch_counter_set_user_access(void)
> {
> u32 cntkctl;
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 41c6946..a4981d2 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -109,3 +109,11 @@ config VF_PIT_TIMER
> bool
> help
> Support for Period Interrupt Timer on Freescale Vybrid Family SoCs.
> +menu "Clock Source"
> +
> +config ARM_ARCH_TIMER_USE_PHYCNT
> + bool "Use Physical Count Timer"
> + depends on ARM_ARCH_TIMER
> + help
> + If bootloader dont set Virtual Offset register,Physical Count
> Timer is needed to replace Virtual Count Timer.
> +endmenu
This cannot be a compile-time option as above in a multiplatform build.
Other paltforms (e.g. KVM guests) *must* use the virtual counters to get
any semblance of a consistent view of time.
Why can the bootloader not be fixed to set CNTVOFF (or to boot the
kernel in Hyp mode)?
Thanks,
Mark.
> diff --git a/drivers/clocksource/arm_arch_timer.c
> b/drivers/clocksource/arm_arch_timer.c
> index fbd9ccd..884e4d1 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -372,7 +372,11 @@ static u64 arch_counter_get_cntvct_mem(void)
> * to exist on arm64. arm doesn't use this before DT is probed so even
> * if we don't have the cp15 accessors we won't have a problem.
> */
> -u64 (*arch_timer_read_counter)(void) = arch_counter_get_cntvct;
> +#ifdef CONFIG_ARM_ARCH_TIMER_USE_PHYCNT
> + u64 (*arch_timer_read_counter)(void) = arch_counter_get_cntpct;
> +#else
> + u64 (*arch_timer_read_counter)(void) = arch_counter_get_cntvct;
> +#endif
>
> static cycle_t arch_counter_read(struct clocksource *cs)
> {
> @@ -410,7 +414,11 @@ static void __init arch_counter_register(unsigned type)
>
> /* Register the CP15 based counter if we have one */
> if (type & ARCH_CP15_TIMER)
> +#ifdef CONFIG_ARM_ARCH_TIMER_USE_PHYCNT
> + arch_timer_read_counter = arch_counter_get_cntpct;
> +#else
> arch_timer_read_counter = arch_counter_get_cntvct;
> +#endif
> else
> arch_timer_read_counter = arch_counter_get_cntvct_mem;
>
> --
> 1.7.9.5
>
>
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