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Commit 3f61c80e authored by Marc Zyngier's avatar Marc Zyngier
Browse files

ARM: architected timers: Add A15 specific sched_clock implementation 



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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 022c03a2

arch/arm/include/asm/arch_timer.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -9,11 +9,17 @@ struct arch_timer { 




#ifdef CONFIG_ARM_ARCH_TIMER

#ifdef CONFIG_ARM_ARCH_TIMER

int arch_timer_register(struct arch_timer *);

int arch_timer_register(struct arch_timer *);

int arch_timer_sched_clock_init(void);

#else

#else

static inline int arch_timer_register(struct arch_timer *at)

static inline int arch_timer_register(struct arch_timer *at)

{

{

	return -ENXIO;

	return -ENXIO;

}

}



static inline int arch_timer_sched_clock_init(void)

{

	return -ENXIO;

}

#endif

#endif





#endif
 
#endif

arch/arm/kernel/arch_timer.c

+25 −0
Original line number Original line Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <asm/localtimer.h>

#include <asm/localtimer.h>

#include <asm/arch_timer.h>

#include <asm/arch_timer.h>

#include <asm/system_info.h>

#include <asm/system_info.h>

#include <asm/sched_clock.h>





static unsigned long arch_timer_rate;

static unsigned long arch_timer_rate;

static int arch_timer_ppi;

static int arch_timer_ppi;
@@ -204,6 +205,18 @@ static inline cycle_t arch_counter_get_cntvct(void) 
	return ((cycle_t) cvalh << 32) | cvall;

	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)

static cycle_t arch_counter_read(struct clocksource *cs)

{

{

	return arch_counter_get_cntpct();

	return arch_counter_get_cntpct();
@@ -286,3 +299,15 @@ int __init arch_timer_register(struct arch_timer *at) 




	return err;

	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;

}