[PATCH 2/5] Added functions mapping TSC value to system time

Christopher Hall
2015-07-28T00:47:21Z

* tsc_to_rawmono64
* tsc_to_realtime64
* tsc_to_mono64

These function build on the counter_to_* time translation function
specifically for TSC based system clock

Signed-off-by: Christopher Hall <christopher.s.hall@intel.com>
---
arch/x86/include/asm/tsc.h | 5 +++++
arch/x86/kernel/tsc.c | 18 ++++++++++++++++++
2 files changed, 23 insertions(+)

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 94605c0..3fdf8b1 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -5,6 +5,7 @@
#define _ASM_X86_TSC_H

#include <asm/processor.h>
+#include <linux/time64.h>

#define NS_SCALE 10 /* 2^10, carefully chosen */
#define US_SCALE 32 /* 2^32, arbitralrily chosen */
@@ -52,6 +53,10 @@ extern int check_tsc_unstable(void);
extern int check_tsc_disabled(void);
extern unsigned long native_calibrate_tsc(void);

+extern int tsc_to_rawmono64(struct timespec64 *rawmono, cycle_t counterval);
+extern int tsc_to_realtime64(struct timespec64 *realtime, cycle_t counterval);
+extern int tsc_to_mono64(struct timespec64 *mono, cycle_t counterval);
+
extern int tsc_clocksource_reliable;

/*
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7437b41..a192271 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -979,6 +979,24 @@ static cycle_t read_tsc(struct clocksource *cs)
return (cycle_t)get_cycles();
}

+int tsc_to_rawmono64(struct timespec64 *rawmono, cycle_t counterval)
+{
+ return counter_to_rawmono64(rawmono, counterval, &clocksource_tsc);
+}
+EXPORT_SYMBOL(tsc_to_rawmono64);
+
+int tsc_to_realtime64(struct timespec64 *realtime, cycle_t counterval)
+{
+ return counter_to_realtime64(realtime, counterval, &clocksource_tsc);
+}
+EXPORT_SYMBOL(tsc_to_realtime64);
+
+int tsc_to_mono64(struct timespec64 *mono, cycle_t counterval)
+{
+ return counter_to_mono64(mono, counterval, &clocksource_tsc);
+}
+EXPORT_SYMBOL(tsc_to_mono64);
+
/*
* .mask MUST be CLOCKSOURCE_MASK(64). See comment above read_tsc()
*/
--
1.9.1