linux-kernel - [PATCHv3 3/3] arm64: Move to generic sched

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Date:	Wed,  5 Jun 2013 16:54:45 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	John Stultz <john.stultz@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Russell King <linux@....linux.org.uk>, arm@...nel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Christopher Covington <cov@...eaurora.org>
Subject: [PATCHv3 3/3] arm64: Move to generic sched_clock infrastructure

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@...eaurora.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.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;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

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