Commit 65cd4f6c authored by Stephen Boyd's avatar Stephen Boyd Committed by John Stultz
Browse files

arch_timer: Move to generic sched_clock framework 



Register with the generic sched_clock framework now that it
supports 64 bits. This fixes two problems with the current
sched_clock support for machines using the architected timers.
First off, we don't subtract the start value from subsequent
sched_clock calls so we can potentially start off with
sched_clock returning gigantic numbers. Second, there is no
support for suspend/resume handling so problems such as discussed
in 6a4dae5e (ARM: 7565/1: sched: stop sched_clock() during
suspend, 2012-10-23) can happen without this patch. Finally, it
allows us to move the sched_clock setup into drivers clocksource
out of the arch ports.

Cc: Christopher Covington <cov@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 07783397

arch/arm/kernel/arch_timer.c

+0 −14
Original line number Diff line number Diff line
@@ -11,7 +11,6 @@ 
#include <linux/init.h>

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/sched_clock.h>



#include <asm/delay.h>
@@ -22,13 +21,6 @@ static unsigned long arch_timer_read_counter_long(void) 
	return arch_timer_read_counter();

}



static u32 sched_clock_mult __read_mostly;



static unsigned long long notrace arch_timer_sched_clock(void)

{

	return arch_timer_read_counter() * sched_clock_mult;

}



static struct delay_timer arch_delay_timer;



static void __init arch_timer_delay_timer_register(void)
@@ -48,11 +40,5 @@ int __init arch_timer_arch_init(void) 


	arch_timer_delay_timer_register();



	/* Cache the sched_clock multiplier to save a divide in the hot path. */

	sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;

	sched_clock_func = arch_timer_sched_clock;

	pr_info("sched_clock: ARM arch timer >56 bits at %ukHz, resolution %uns\n",

		arch_timer_rate / 1000, sched_clock_mult);



	return 0;

}

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ config ARM64 
	select GENERIC_IOMAP

	select GENERIC_IRQ_PROBE

	select GENERIC_IRQ_SHOW

	select GENERIC_SCHED_CLOCK

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_TIME_VSYSCALL

	select HARDIRQS_SW_RESEND

arch/arm64/kernel/time.c

+0 −10
Original line number Diff line number Diff line
@@ -61,13 +61,6 @@ unsigned long profile_pc(struct pt_regs *regs) 
EXPORT_SYMBOL(profile_pc);

#endif



static u64 sched_clock_mult __read_mostly;



unsigned long long notrace sched_clock(void)

{

	return arch_timer_read_counter() * sched_clock_mult;

}



void __init time_init(void)

{

	u32 arch_timer_rate;
@@ -78,9 +71,6 @@ void __init time_init(void) 
	if (!arch_timer_rate)

		panic("Unable to initialise architected timer.\n");



	/* Cache the sched_clock multiplier to save a divide in the hot path. */

	sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;



	/* Calibrate the delay loop directly */

	lpj_fine = arch_timer_rate / HZ;

}

drivers/clocksource/arm_arch_timer.c

+10 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/of_address.h>

#include <linux/io.h>

#include <linux/slab.h>

#include <linux/sched_clock.h>



#include <asm/arch_timer.h>

#include <asm/virt.h>
@@ -471,6 +472,15 @@ static int __init arch_timer_register(void) 
		goto out;

	}



	clocksource_register_hz(&clocksource_counter, arch_timer_rate);

	cyclecounter.mult = clocksource_counter.mult;

	cyclecounter.shift = clocksource_counter.shift;

	timecounter_init(&timecounter, &cyclecounter,

			 arch_counter_get_cntvct());



	/* 56 bits minimum, so we assume worst case rollover */

	sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);



	if (arch_timer_use_virtual) {

		ppi = arch_timer_ppi[VIRT_PPI];

		err = request_percpu_irq(ppi, arch_timer_handler_virt,

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