From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 1/2] arm_arch_timer: Expose event stream status
Date: Wed, 11 Oct 2017 16:14:10 +0100 [thread overview]
Message-ID: <20171011151409.GB14341@arm.com> (raw)
In-Reply-To: <1506682350-9023-2-git-send-email-julien.thierry@arm.com>
Hi Julien,
On Fri, Sep 29, 2017 at 11:52:29AM +0100, Julien Thierry wrote:
> The arch timer configuration for a CPU might get reset after suspending
> said CPU.
>
> In order to reliably use the event stream in the kernel (e.g. for delays),
> we keep track of the state where we can safely concider the event stream as
> properly configured.
>
> Signed-off-by: Julien Thierry <julien.thierry@arm•com>
> Cc: Mark Rutland <mark.rutland@arm•com>
> Cc: Marc Zyngier <marc.zyngier@arm•com>
> Cc: Russell King <linux@armlinux•org.uk>
> Cc: Catalin Marinas <catalin.marinas@arm•com>
> Cc: Will Deacon <will.deacon@arm•com>
> ---
> arch/arm/include/asm/arch_timer.h | 1 +
> arch/arm64/include/asm/arch_timer.h | 1 +
> drivers/clocksource/arm_arch_timer.c | 20 ++++++++++++++++++--
> include/clocksource/arm_arch_timer.h | 6 ++++++
> 4 files changed, 26 insertions(+), 2 deletions(-)
The arch-timer bits needs an ack from Marc or Mark.
> diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
> index d4ebf56..0b6e104 100644
> --- a/arch/arm/include/asm/arch_timer.h
> +++ b/arch/arm/include/asm/arch_timer.h
> @@ -106,6 +106,7 @@ static inline u32 arch_timer_get_cntkctl(void)
> static inline void arch_timer_set_cntkctl(u32 cntkctl)
> {
> asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
> + isb();
> }
>
> #endif
> diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
> index a652ce0..bdedd8f 100644
> --- a/arch/arm64/include/asm/arch_timer.h
> +++ b/arch/arm64/include/asm/arch_timer.h
> @@ -144,6 +144,7 @@ static inline u32 arch_timer_get_cntkctl(void)
> static inline void arch_timer_set_cntkctl(u32 cntkctl)
> {
> write_sysreg(cntkctl, cntkctl_el1);
> + isb();
> }
>
> static inline u64 arch_counter_get_cntpct(void)
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index fd4b7f6..47cf15e 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -77,6 +77,7 @@ struct arch_timer {
> static bool arch_counter_suspend_stop;
> static bool vdso_default = true;
>
> +static cpumask_t evtstrm_available;
> static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
>
> static int __init early_evtstrm_cfg(char *buf)
> @@ -740,6 +741,7 @@ static void arch_timer_evtstrm_enable(int divider)
> #ifdef CONFIG_COMPAT
> compat_elf_hwcap |= COMPAT_HWCAP_EVTSTRM;
> #endif
> + cpumask_set_cpu(smp_processor_id(), &evtstrm_available);
> }
>
> static void arch_timer_configure_evtstream(void)
> @@ -864,6 +866,11 @@ u32 arch_timer_get_rate(void)
> return arch_timer_rate;
> }
>
> +bool arch_timer_evtstrm_available(void)
> +{
> + return !!cpumask_test_cpu(smp_processor_id(), &evtstrm_available);
> +}
I don't think you need the '!!' prefix here.
> +
> static u64 arch_counter_get_cntvct_mem(void)
> {
> u32 vct_lo, vct_hi, tmp_hi;
> @@ -929,6 +936,8 @@ static int arch_timer_dying_cpu(unsigned int cpu)
> {
> struct clock_event_device *clk = this_cpu_ptr(arch_timer_evt);
>
> + cpumask_clear_cpu(smp_processor_id(), &evtstrm_available);
> +
> arch_timer_stop(clk);
> return 0;
> }
> @@ -938,10 +947,16 @@ static int arch_timer_dying_cpu(unsigned int cpu)
> static int arch_timer_cpu_pm_notify(struct notifier_block *self,
> unsigned long action, void *hcpu)
> {
> - if (action == CPU_PM_ENTER)
> + if (action == CPU_PM_ENTER) {
> __this_cpu_write(saved_cntkctl, arch_timer_get_cntkctl());
> - else if (action == CPU_PM_ENTER_FAILED || action == CPU_PM_EXIT)
> +
> + cpumask_clear_cpu(smp_processor_id(), &evtstrm_available);
> + } else if (action == CPU_PM_ENTER_FAILED || action == CPU_PM_EXIT) {
> arch_timer_set_cntkctl(__this_cpu_read(saved_cntkctl));
> +
> + if (elf_hwcap & HWCAP_EVTSTRM)
> + cpumask_set_cpu(smp_processor_id(), &evtstrm_available);
> + }
> return NOTIFY_OK;
> }
>
> @@ -1017,6 +1032,7 @@ static int __init arch_timer_register(void)
> if (err)
> goto out_unreg_notify;
>
> + cpumask_clear(&evtstrm_available);
This should already be ok by virtue of the mask being static, no?
Alternatively, you could use the CPU_MASK_NONE static initialiser.
Will
next prev parent reply other threads:[~2017-10-11 15:14 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-29 10:52 [PATCH v3 0/2] WFE for long delays Julien Thierry
2017-09-29 10:52 ` [PATCH v3 1/2] arm_arch_timer: Expose event stream status Julien Thierry
2017-10-11 15:14 ` Will Deacon [this message]
2017-10-12 8:38 ` Julien Thierry
2017-10-12 8:58 ` Julien Thierry
2017-10-12 9:27 ` Suzuki K Poulose
2017-10-12 9:30 ` Will Deacon
2017-10-12 9:40 ` Julien Thierry
2017-10-12 10:26 ` Will Deacon
2017-10-12 12:28 ` Julien Thierry
2017-09-29 10:52 ` [PATCH v3 2/2] arm64: use WFE for long delays Julien Thierry
2017-10-11 15:13 ` Will Deacon
2017-10-12 8:47 ` Julien Thierry
2017-10-12 8:52 ` Will Deacon
2017-10-12 8:54 ` Julien Thierry
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