netdev - [patch V2 12/26] timekeeping: Introduce auxiliary timekeepers

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Message-ID: <20250519083026.350061049@linutronix.de>
Date: Mon, 19 May 2025 10:33:28 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: netdev@...r.kernel.org,
 Richard Cochran <richardcochran@...il.com>,
 Christopher Hall <christopher.s.hall@...el.com>,
 John Stultz <jstultz@...gle.com>,
 Frederic Weisbecker <frederic@...nel.org>,
 Anna-Maria Behnsen <anna-maria@...utronix.de>,
 Miroslav Lichvar <mlichvar@...hat.com>,
 Werner Abt <werner.abt@...nberg-usa.com>,
 David Woodhouse <dwmw2@...radead.org>,
 Stephen Boyd <sboyd@...nel.org>,
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
 Kurt Kanzenbach <kurt@...utronix.de>,
 Nam Cao <namcao@...utronix.de>,
 Antoine Tenart <atenart@...nel.org>
Subject: [patch V2 12/26] timekeeping: Introduce auxiliary timekeepers

From: Anna-Maria Behnsen <anna-maria@...utronix.de>

Provide timekeepers for auxiliary clocks and initialize them during
boot.

Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 kernel/time/timekeeping.c |   22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)
---
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -53,7 +53,11 @@ struct tk_data {
 	raw_spinlock_t		lock;
 } ____cacheline_aligned;
 
-static struct tk_data tk_core;
+static struct tk_data timekeeper_data[TIMEKEEPERS_MAX];
+
+/* The core timekeeper */
+#define tk_core		(timekeeper_data[TIMEKEEPER_CORE])
+
 
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
@@ -113,6 +117,12 @@ static struct tk_fast tk_fast_raw  ____c
 	.base[1] = FAST_TK_INIT,
 };
 
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+static __init void tk_aux_setup(void);
+#else
+static inline void tk_aux_setup(void) { }
+#endif
+
 unsigned long timekeeper_lock_irqsave(void)
 {
 	unsigned long flags;
@@ -1589,7 +1599,6 @@ void ktime_get_raw_ts64(struct timespec6
 }
 EXPORT_SYMBOL(ktime_get_raw_ts64);
 
-
 /**
  * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
  */
@@ -1701,6 +1710,7 @@ void __init timekeeping_init(void)
 	struct clocksource *clock;
 
 	tkd_basic_setup(&tk_core, TIMEKEEPER_CORE, true);
+	tk_aux_setup();
 
 	read_persistent_wall_and_boot_offset(&wall_time, &boot_offset);
 	if (timespec64_valid_settod(&wall_time) &&
@@ -2630,3 +2640,11 @@ void hardpps(const struct timespec64 *ph
 }
 EXPORT_SYMBOL(hardpps);
 #endif /* CONFIG_NTP_PPS */
+
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+static __init void tk_aux_setup(void)
+{
+	for (int i = TIMEKEEPER_AUX; i <= TIMEKEEPER_AUX_LAST; i++)
+		tkd_basic_setup(&timekeeper_data[i], i, false);
+}
+#endif /* CONFIG_POSIX_AUX_CLOCKS */