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Subject[PATCH 7/8] x86: tsc: Register the persistent clock
Date
Register the tsc as one persistent clock to compensate the suspend time
if the tsc clocksource is always available.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
arch/x86/Kconfig | 1 +
arch/x86/kernel/tsc.c | 21 +++++++++++++++++++++
2 files changed, 22 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 297789a..549dd01 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -200,6 +200,7 @@ config X86
select USER_STACKTRACE_SUPPORT
select VIRT_TO_BUS
select X86_FEATURE_NAMES if PROC_FS
+ select PERSISTENT_CLOCK

config INSTRUCTION_DECODER
def_bool y
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 74392d9..cb4f495 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -11,6 +11,7 @@
#include <linux/delay.h>
#include <linux/clocksource.h>
#include <linux/percpu.h>
+#include <linux/persistent_clock.h>
#include <linux/timex.h>
#include <linux/static_key.h>

@@ -1032,6 +1033,11 @@ static u64 read_tsc(struct clocksource *cs)
return (u64)rdtsc_ordered();
}

+static u64 notrace tsc_read_persistent_clock(void)
+{
+ return (u64)rdtsc_ordered();
+}
+
static void tsc_cs_mark_unstable(struct clocksource *cs)
{
if (tsc_unstable)
@@ -1300,6 +1306,14 @@ static void tsc_refine_calibration_work(struct work_struct *work)
if (boot_cpu_has(X86_FEATURE_ART))
art_related_clocksource = &clocksource_tsc;
clocksource_register_khz(&clocksource_tsc, tsc_khz);
+
+ if (clocksource_tsc.flags & CLOCK_SOURCE_SUSPEND_NONSTOP) {
+ persistent_clock_init_and_register(tsc_read_persistent_clock,
+ CLOCKSOURCE_MASK(64),
+ tsc_khz * 1000, 0);
+ persistent_clock_start_alarmtimer();
+ }
+
unreg:
clocksource_unregister(&clocksource_tsc_early);
}
@@ -1327,6 +1341,13 @@ static int __init init_tsc_clocksource(void)
if (boot_cpu_has(X86_FEATURE_ART))
art_related_clocksource = &clocksource_tsc;
clocksource_register_khz(&clocksource_tsc, tsc_khz);
+
+ if (clocksource_tsc.flags & CLOCK_SOURCE_SUSPEND_NONSTOP) {
+ persistent_clock_init_and_register(tsc_read_persistent_clock,
+ CLOCKSOURCE_MASK(64),
+ tsc_khz * 1000, 0);
+ persistent_clock_start_alarmtimer();
+ }
unreg:
clocksource_unregister(&clocksource_tsc_early);
return 0;
--
1.7.9.5
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