timekeeping: Provide update for auxiliary timekeepers

Update the auxiliary timekeepers periodically. For now this is tied to the system
timekeeper update from the tick. This might be revisited and moved out of the tick.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.382451331@linutronix.de

Author: KAGA-KOKO

kernel/time/timekeeping.c

@@ -131,9 +131,11 @@ static struct tk_fast tk_fast_raw  ____cacheline_aligned = {
 #ifdef CONFIG_POSIX_AUX_CLOCKS
 static __init void tk_aux_setup(void);
 static void tk_aux_update_clocksource(void);
+static void tk_aux_advance(void);
 #else
 static inline void tk_aux_setup(void) { }
 static inline void tk_aux_update_clocksource(void) { }
+static inline void tk_aux_advance(void) { }
 #endif
 
 unsigned long timekeeper_lock_irqsave(void)
@@ -2317,11 +2319,13 @@ static bool timekeeping_advance(enum timekeeping_adv_mode mode)
 /**
  * update_wall_time - Uses the current clocksource to increment the wall time
  *
+ * It also updates the enabled auxiliary clock timekeepers
  */
 void update_wall_time(void)
 {
 	if (timekeeping_advance(TK_ADV_TICK))
 		clock_was_set_delayed();
+	tk_aux_advance();
 }
 
 /**
@@ -2764,6 +2768,21 @@ static void tk_aux_update_clocksource(void)
 	}
 }
 
+static void tk_aux_advance(void)
+{
+	unsigned long active = READ_ONCE(aux_timekeepers);
+	unsigned int id;
+
+	/* Lockless quick check to avoid extra cache lines */
+	for_each_set_bit(id, &active, BITS_PER_LONG) {
+		struct tk_data *aux_tkd = &timekeeper_data[id + TIMEKEEPER_AUX_FIRST];
+
+		guard(raw_spinlock)(&aux_tkd->lock);
+		if (aux_tkd->shadow_timekeeper.clock_valid)
+			__timekeeping_advance(aux_tkd, TK_ADV_TICK);
+	}
+}
+
 /**
  * ktime_get_aux - Get time for a AUX clock
  * @id:	ID of the clock to read (CLOCK_AUX...)