From: Rob Herring <rob.herr...@calxeda.com>
Commit 023796b (ARM: arch_timer: use full 64-bit counter for sched_clock)
fails to ensure sched_clock always starts at time 0 and counting is
suspended during suspend. arm64 sched_clock support also has the same
issues. This fixes all architected timer users by maintaining an initial
offset which is updated on resume.
Signed-off-by: Rob Herring <rob.herr...@calxeda.com>
Cc: Russell King <li...@arm.linux.org.uk>
Cc: John Stultz <john.stu...@linaro.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Stephen Boyd <sb...@codeaurora.org>
---
arch/arm/kernel/arch_timer.c | 1 +
drivers/clocksource/arm_arch_timer.c | 26 +++++++++++++++++++++++++-
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index df6825e..9a517fe 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -42,5 +42,6 @@ int __init arch_timer_arch_init(void)
arch_timer_delay_timer_register();
sched_clock_func = arch_timer_sched_clock;
+
return 0;
}
diff --git a/drivers/clocksource/arm_arch_timer.c
b/drivers/clocksource/arm_arch_timer.c
index 17ed8e4..cc0bd67 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -17,6 +17,7 @@
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/io.h>
+#include <linux/syscore_ops.h>
#include <asm/arch_timer.h>
#include <asm/virt.h>
@@ -267,14 +268,34 @@ static struct notifier_block arch_timer_cpu_nb
__cpuinitdata = {
};
static u64 sched_clock_mult __read_mostly;
+static u64 arch_timer_suspend_cyc;
+static u64 arch_timer_sched_clock_offset;
unsigned long long notrace arch_timer_sched_clock(void)
{
- return arch_timer_read_counter() * sched_clock_mult;
+ u64 cyc = arch_timer_read_counter() - arch_timer_sched_clock_offset;
+ return cyc * sched_clock_mult;
}
unsigned long long sched_clock(void) \
__attribute__((weak, alias("arch_timer_sched_clock")));
+static int arch_timer_suspend(void)
+{
+ arch_timer_suspend_cyc = arch_timer_read_counter();
+ return 0;
+}
+
+static void arch_timer_resume(void)
+{
+ arch_timer_sched_clock_offset +=
+ arch_timer_read_counter() - arch_timer_suspend_cyc;
+}
+
+static struct syscore_ops arch_timer_ops = {
+ .suspend = arch_timer_suspend,
+ .resume = arch_timer_resume,
+};
+
static int __init arch_timer_register(void)
{
int err;
@@ -332,6 +353,9 @@ static int __init arch_timer_register(void)
pr_info("sched_clock: ARM arch timer >56 bits at %ukHz, resolution
%lluns\n",
arch_timer_rate / 1000, sched_clock_mult);
+ arch_timer_sched_clock_offset = arch_timer_read_counter();
+ register_syscore_ops(&arch_timer_ops);
+
return 0;
out_free_irq:
--
1.7.10.4
--
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