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arm_arch_timer: Expose event stream status

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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>
This commit is contained in:
Julien Thierry
2017-10-13 14:32:55 +01:00
committed by Will Deacon
parent 611a7bc74e
commit ec5c8e429d
4 changed files with 30 additions and 3 deletions
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6
include/clocksource/arm_arch_timer.h
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@@ -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