[PATCHv3 3/3] arm64: Move to generic sched_clock infrastructure

Stephen Boyd
2013-06-05T23:55:08Z

Use the generic sched_clock infrastructure instead of rolling our
own. This has the added benefit of fixing suspend/resume as
outlined in 6a4dae5 (ARM: 7565/1: sched: stop sched_clock()
during suspend, 2012-10-23) and correcting the timestamps when
the hardware returns a value instead of 0 upon the first read.

Cc: Christopher Covington <cov@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
arch/arm64/Kconfig | 1 +
arch/arm64/kernel/time.c | 11 ++---------
2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 56b3f6d..f9c6e92 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -13,6 +13,7 @@ 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
diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
index a551f88..a98eb8b 100644
--- a/arch/arm64/kernel/time.c
+++ b/arch/arm64/kernel/time.c
@@ -33,6 +33,7 @@
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/clocksource.h>
+#include <linux/sched_clock.h>

#include <clocksource/arm_arch_timer.h>

@@ -61,13 +62,6 @@ 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;
-}
-
int read_current_timer(unsigned long *timer_value)
{
*timer_value = arch_timer_read_counter();
@@ -84,8 +78,7 @@ 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;
+ sched_clock_setup(arch_timer_read_counter, 56, arch_timer_rate);

/* Calibrate the delay loop directly */
lpj_fine = arch_timer_rate / HZ;