From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
In some scenario like return device time to ptp_kvm guest,
we need identify the current clocksource outside core time code.
This patch add a mechanism to recognize the current clocksource
by export clocksource id in time_get_snapshot.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
---
include/linux/clocksource.h | 6 ++++++
include/linux/timekeeping.h | 12 +++++++-----
kernel/time/clocksource.c | 3 +++
kernel/time/timekeeping.c | 1 +
4 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index b21db536fd52..ac8016b22734 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -19,6 +19,7 @@
#include <linux/of.h>
#include <asm/div64.h>
#include <asm/io.h>
+#include <linux/clocksource_ids.h>
struct clocksource;
struct module;
@@ -49,6 +50,10 @@ struct module;
* 400-499: Perfect
* The ideal clocksource. A must-use where
* available.
+ * @id: Defaults to CSID_GENERIC. The id value is captured
+ * in certain snapshot functions to allow callers to
+ * validate the clocksource from which the snapshot was
+ * taken.
* @read: returns a cycle value, passes clocksource as argument
* @enable: optional function to enable the clocksource
* @disable: optional function to disable the clocksource
@@ -91,6 +96,7 @@ struct clocksource {
const char *name;
struct list_head list;
int rating;
+ enum clocksource_ids id;
int (*enable)(struct clocksource *cs);
void (*disable)(struct clocksource *cs);
unsigned long flags;
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index a8ab0f143ac4..ecce56269a7e 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -2,6 +2,7 @@
#ifndef _LINUX_TIMEKEEPING_H
#define _LINUX_TIMEKEEPING_H
+#include <linux/clocksource_ids.h>
#include <linux/errno.h>
/* Included from linux/ktime.h */
@@ -204,11 +205,12 @@ extern void timekeeping_inject_sleeptime64(const struct timespec64 *delta);
* @cs_was_changed_seq: The sequence number of clocksource change events
*/
struct system_time_snapshot {
- u64 cycles;
- ktime_t real;
- ktime_t raw;
- unsigned int clock_was_set_seq;
- u8 cs_was_changed_seq;
+ u64 cycles;
+ ktime_t real;
+ ktime_t raw;
+ enum clocksource_ids cs_id;
+ unsigned int clock_was_set_seq;
+ u8 cs_was_changed_seq;
};
/*
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 3bcc19ceb073..26a3add61771 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -921,6 +921,9 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
clocksource_arch_init(cs);
+ if (WARN_ON_ONCE((unsigned int)cs->id >= CSID_MAX))
+ cs->id = CSID_GENERIC;
+
/* Initialize mult/shift and max_idle_ns */
__clocksource_update_freq_scale(cs, scale, freq);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 44b726bab4bd..88078cff7fe2 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -974,6 +974,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
do {
seq = read_seqcount_begin(&tk_core.seq);
now = tk_clock_read(&tk->tkr_mono);
+ systime_snapshot->cs_id = tk->tkr_mono.clock->id;
systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
base_real = ktime_add(tk->tkr_mono.base,
--
2.17.1
