blob: 9610caf32226e27e0c5577e9cc89a2a1479fed1c [file] [log] [blame]
From 419c8ec298950d2cdc08b3677a3368b84289ac33 Mon Sep 17 00:00:00 2001
From: Julien Thierry <julien.thierry@arm.com>
Date: Fri, 13 Oct 2017 14:32:55 +0100
Subject: [PATCH 0008/1795] arm_arch_timer: Expose event stream status
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 consider the event stream as
properly configured. After writing to cntkctl, we issue an ISB to ensure
that subsequent delay loops can rely on the event stream being enabled.
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: 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>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit ec5c8e429d07737ee94ee1fd2ae5029547484194)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
arch/arm/include/asm/arch_timer.h | 1 +
arch/arm64/include/asm/arch_timer.h | 1 +
drivers/clocksource/arm_arch_timer.c | 25 ++++++++++++++++++++++---
include/clocksource/arm_arch_timer.h | 6 ++++++
4 files changed, 30 insertions(+), 3 deletions(-)
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 9327e3a101dc..0a8d7bba2cb0 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -107,6 +107,7 @@ 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 a652ce0a5cb2..bdedd8f748d1 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 14e2419063e9..a926e62444b0 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -77,6 +77,7 @@ static bool arch_timer_mem_use_virtual;
static bool arch_counter_suspend_stop;
static bool vdso_default = true;
+static cpumask_t evtstrm_available = CPU_MASK_NONE;
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 +866,16 @@ u32 arch_timer_get_rate(void)
return arch_timer_rate;
}
+bool arch_timer_evtstrm_available(void)
+{
+ /*
+ * We might get called from a preemptible context. This is fine
+ * because availability of the event stream should be always the same
+ * for a preemptible context and context where we might resume a task.
+ */
+ return cpumask_test_cpu(raw_smp_processor_id(), &evtstrm_available);
+}
+
static u64 arch_counter_get_cntvct_mem(void)
{
u32 vct_lo, vct_hi, tmp_hi;
@@ -929,6 +941,8 @@ 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 +952,16 @@ static DEFINE_PER_CPU(unsigned long, saved_cntkctl);
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;
}
@@ -1017,7 +1037,6 @@ static int __init arch_timer_register(void)
if (err)
goto out_unreg_notify;
-
/* Register and immediately configure the timer on the boot CPU */
err = cpuhp_setup_state(CPUHP_AP_ARM_ARCH_TIMER_STARTING,
"clockevents/arm/arch_timer:starting",
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index cc805b72994a..4e28283e2ec6 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -93,6 +93,7 @@ struct arch_timer_mem {
extern u32 arch_timer_get_rate(void);
extern u64 (*arch_timer_read_counter)(void);
extern struct arch_timer_kvm_info *arch_timer_get_kvm_info(void);
+extern bool arch_timer_evtstrm_available(void);
#else
@@ -106,6 +107,11 @@ static inline u64 arch_timer_read_counter(void)
return 0;
}
+static inline bool arch_timer_evtstrm_available(void)
+{
+ return false;
+}
+
#endif
#endif
--
2.19.0