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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 6a4dae5 (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: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Stephen Boyd 2013-07-18 16:21:18 -07:00 committed by John Stultz
parent 07783397c6
commit 65cd4f6c99
4 changed files with 11 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/arm/kernel/arch_timer.c
View File

@ -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;
}

1
arch/arm64/Kconfig
View File

@ -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

10
arch/arm64/kernel/time.c
View File

@ -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;
}

10
drivers/clocksource/arm_arch_timer.c
View File

@ -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,