4 files changed, 74 insertions, 36 deletions

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index b12a6d19aa60..283d7297aa79 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -32,6 +32,21 @@ struct module;
 #include <vdso/clocksource.h>
 
 /**
+ * struct clocksource_hw_snapshot - Snapshot for the underlying hardware counter of derived
+ *				    clocksources like kvmclock or Hyper-V scaled TSC
+ * @hw_cycles:		The hardware counter value
+ * @hw_csid:		Clocksource ID of the hardware counter
+ *
+ * Such clocksources must implement the read_snapshot() callback and fill in the
+ * hardware counter value, the clocksource ID of the hardware counter and derive
+ * the actual clocksource cycles from @hw_cycles to provide an atomic snapshot
+ */
+struct clocksource_hw_snapshot {
+	u64			hw_cycles;
+	enum clocksource_ids	hw_csid;
+};
+
+/**
  * struct clocksource - hardware abstraction for a free running counter
  *	Provides mostly state-free accessors to the underlying hardware.
  *	This is the structure used for system time.
@@ -72,6 +87,14 @@ struct module;
  * @flags:		Flags describing special properties
  * @base:		Hardware abstraction for clock on which a clocksource
  *			is based
+ * @read_snapshot:	Extended @read() function for clocksources such as
+ *			kvmclock or the Hyper-V scaled TSC where the actual
+ *			clocksource value for timekeeping is calculated from an
+ *			underlying hardware counter. Returns the timekeeping
+ *			relevant cycle value and stores the raw value of the
+ *			underlying counter from which it was calculated
+ *			including the clocksource ID of that counter in the
+ *			clocksource hardware snapshot.
  * @enable:		Optional function to enable the clocksource
  * @disable:		Optional function to disable the clocksource
  * @suspend:		Optional suspend function for the clocksource
@@ -113,6 +136,7 @@ struct clocksource {
 	unsigned long		flags;
 	struct clocksource_base *base;
 
+	u64			(*read_snapshot)(struct clocksource *cs, struct clocksource_hw_snapshot *chs);
 	int			(*enable)(struct clocksource *cs);
 	void			(*disable)(struct clocksource *cs);
 	void			(*suspend)(struct clocksource *cs);
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index aab0aebb529e..9f088c9023b1 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -99,12 +99,14 @@ static inline void timespec_to_pps_ktime(struct pps_ktime *kt,
 
 static inline void pps_get_ts(struct pps_event_time *ts)
 {
+#ifdef CONFIG_NTP_PPS
 	struct system_time_snapshot snap;
 
-	ktime_get_snapshot(&snap);
-	ts->ts_real = ktime_to_timespec64(snap.real);
-#ifdef CONFIG_NTP_PPS
-	ts->ts_raw = ktime_to_timespec64(snap.raw);
+	ktime_get_snapshot_id(CLOCK_REALTIME, &snap);
+	ts->ts_real = ktime_to_timespec64(snap.systime);
+	ts->ts_raw = ktime_to_timespec64(snap.monoraw);
+#else
+	ktime_get_real_ts64(&ts->ts_real);
 #endif
 }
 
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 884364596dd3..36a27a910595 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -12,6 +12,7 @@
 #include <linux/pps_kernel.h>
 #include <linux/ptp_clock.h>
 #include <linux/timecounter.h>
+#include <linux/timekeeping.h>
 #include <linux/skbuff.h>
 
 #define PTP_CLOCK_NAME_LEN	32
@@ -45,13 +46,13 @@ struct system_device_crosststamp;
 
 /**
  * struct ptp_system_timestamp - system time corresponding to a PHC timestamp
- * @pre_ts: system timestamp before capturing PHC
- * @post_ts: system timestamp after capturing PHC
- * @clockid: clock-base used for capturing the system timestamps
+ * @pre_sts:	system time snapshot before capturing PHC
+ * @post_sts:	system time snapshot after capturing PHC
+ * @clockid:	clock-base used for capturing the system timestamps
  */
 struct ptp_system_timestamp {
-	struct timespec64 pre_ts;
-	struct timespec64 post_ts;
+	struct system_time_snapshot pre_sts;
+	struct system_time_snapshot post_sts;
 	clockid_t clockid;
 };
 
@@ -510,13 +511,13 @@ static inline ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp,
 static inline void ptp_read_system_prets(struct ptp_system_timestamp *sts)
 {
 	if (sts)
-		ktime_get_clock_ts64(sts->clockid, &sts->pre_ts);
+		ktime_get_snapshot_id(sts->clockid, &sts->pre_sts);
 }
 
 static inline void ptp_read_system_postts(struct ptp_system_timestamp *sts)
 {
 	if (sts)
-		ktime_get_clock_ts64(sts->clockid, &sts->post_ts);
+		ktime_get_snapshot_id(sts->clockid, &sts->post_sts);
 }
 
 #endif
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index aee2c1a46e47..984a866d293b 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -276,37 +276,30 @@ static inline bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt) { ret
 #endif
 
 /**
- * struct system_time_snapshot - simultaneous raw/real time capture with
- *				 counter value
- * @cycles:	Clocksource counter value to produce the system times
- * @real:	Realtime system time
- * @boot:	Boot time
- * @raw:	Monotonic raw system time
- * @cs_id:	Clocksource ID
+ * struct system_time_snapshot - Simultaneous time capture of CLOCK_MONOTONIC_RAW,
+ *				 a selected CLOCK_* and the clocksource counter value
+ * @cycles:		Clocksource counter value to produce the system times
+ * @hw_cycles:		For derived clocksources, the hardware counter value from
+ *			which @cycles was derived
+ * @systime:		The system time of the selected CLOCK ID
+ * @monoraw:		Monotonic raw system time
+ * @cs_id:		Clocksource ID
+ * @hw_csid:		Clocksource ID of the underlying hardware counter for derived
+ *			clocksources which implement the read_snapshot() callback.
  * @clock_was_set_seq:	The sequence number of clock-was-set events
  * @cs_was_changed_seq:	The sequence number of clocksource change events
+ * @valid:		True if the snapshot is valid
  */
 struct system_time_snapshot {
 	u64			cycles;
-	ktime_t			real;
-	ktime_t			boot;
-	ktime_t			raw;
+	u64			hw_cycles;
+	ktime_t			systime;
+	ktime_t			monoraw;
 	enum clocksource_ids	cs_id;
+	enum clocksource_ids	hw_csid;
 	unsigned int		clock_was_set_seq;
 	u8			cs_was_changed_seq;
-};
-
-/**
- * struct system_device_crosststamp - system/device cross-timestamp
- *				      (synchronized capture)
- * @device:		Device time
- * @sys_realtime:	Realtime simultaneous with device time
- * @sys_monoraw:	Monotonic raw simultaneous with device time
- */
-struct system_device_crosststamp {
-	ktime_t device;
-	ktime_t sys_realtime;
-	ktime_t sys_monoraw;
+	u8			valid;
 };
 
 /**
@@ -325,6 +318,23 @@ struct system_counterval_t {
 	bool			use_nsecs;
 };
 
+/**
+ * struct system_device_crosststamp - system/device cross-timestamp
+ *				      (synchronized capture)
+ * @clock_id:		System time Clock ID to capture
+ * @device:		Device time
+ * @sys_counter:	Clocksource counter value simultaneous with device time
+ * @sys_systime:	System time for @clock_id
+ * @sys_monoraw:	Monotonic raw simultaneous with device time
+ */
+struct system_device_crosststamp {
+	clockid_t			clock_id;
+	ktime_t				device;
+	struct system_counterval_t	sys_counter;
+	ktime_t				sys_systime;
+	ktime_t				sys_monoraw;
+};
+
 extern bool ktime_real_to_base_clock(ktime_t treal,
 				     enum clocksource_ids base_id, u64 *cycles);
 extern bool timekeeping_clocksource_has_base(enum clocksource_ids id);
@@ -341,9 +351,10 @@ extern int get_device_system_crosststamp(
 			struct system_device_crosststamp *xtstamp);
 
 /*
- * Simultaneously snapshot realtime and monotonic raw clocks
+ * Simultaneously snapshot a given clock with MONOTONIC_RAW and the underlying
+ * clocksource counter value.
  */
-extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
+extern void ktime_get_snapshot_id(clockid_t clock_id, struct system_time_snapshot *systime_snapshot);
 
 /*
  * Persistent clock related interfaces