timekeeping: Provide ktime_get_ntp_seconds()

ntp_adjtimex() requires access to the actual time keeper per timekeeper
ID. Provide an interface.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250519083026.411809421@linutronix.de

Author: KAGA-KOKO

kernel/time/timekeeping.c

@@ -2627,6 +2627,15 @@ int do_adjtimex(struct __kernel_timex *txc)
 	return ret;
 }
 
+/*
+ * Invoked from NTP with the time keeper lock held, so lockless access is
+ * fine.
+ */
+long ktime_get_ntp_seconds(unsigned int id)
+{
+	return timekeeper_data[id].timekeeper.xtime_sec;
+}
+
 #ifdef CONFIG_NTP_PPS
 /**
  * hardpps() - Accessor function to NTP __hardpps function

kernel/time/timekeeping_internal.h

@@ -45,4 +45,7 @@ static inline u64 clocksource_delta(u64 now, u64 last, u64 mask, u64 max_delta)
 unsigned long timekeeper_lock_irqsave(void);
 void timekeeper_unlock_irqrestore(unsigned long flags);
 
+/* NTP specific interface to access the current seconds value */
+long ktime_get_ntp_seconds(unsigned int id);
+
 #endif /* _TIMEKEEPING_INTERNAL_H */