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ARM: architected timers: Add A15 specific sched_clock implementation

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Provide an A15 sched_clock implementation using the virtual counter,
which is thought to be more useful than the physical one in a
virtualised environment, as it can offset the time spent in another
VM or the hypervisor.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2011-01-14 15:32:36 +00:00
parent 022c03a2d6
commit 3f61c80eb7
2 changed files with 31 additions and 0 deletions
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6
arch/arm/include/asm/arch_timer.h
View file

@ -9,11 +9,17 @@ struct arch_timer {
#ifdef CONFIG_ARM_ARCH_TIMER
int arch_timer_register(struct arch_timer *);
int arch_timer_sched_clock_init(void);
#else
static inline int arch_timer_register(struct arch_timer *at)
{
return -ENXIO;
}
static inline int arch_timer_sched_clock_init(void)
{
return -ENXIO;
}
#endif
#endif

25
arch/arm/kernel/arch_timer.c
View file

@ -23,6 +23,7 @@
#include <asm/localtimer.h>
#include <asm/arch_timer.h>
#include <asm/system_info.h>
#include <asm/sched_clock.h>
static unsigned long arch_timer_rate;
static int arch_timer_ppi;
@ -204,6 +205,18 @@ static inline cycle_t arch_counter_get_cntvct(void)
return ((cycle_t) cvalh << 32) | cvall;
}
static u32 notrace arch_counter_get_cntvct32(void)
{
cycle_t cntvct = arch_counter_get_cntvct();
/*
* The sched_clock infrastructure only knows about counters
* with at most 32bits. Forget about the upper 24 bits for the
* time being...
*/
return (u32)(cntvct & (u32)~0);
}
static cycle_t arch_counter_read(struct clocksource *cs)
{
return arch_counter_get_cntpct();
@ -286,3 +299,15 @@ int __init arch_timer_register(struct arch_timer *at)
return err;
}
int __init arch_timer_sched_clock_init(void)
{
int err;
err = arch_timer_available();
if (err)
return err;
setup_sched_clock(arch_counter_get_cntvct32, 32, arch_timer_rate);
return 0;
}