[tip: timers/ptp] timekeeping: Add minimal posix-timers support for auxiliary clocks

["tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>]

The following commit has been merged into the timers/ptp branch of tip:

Commit-ID:     606424bf4ffd9d27865c45b5707c1edac6b187ed
Gitweb:        https://git.kernel.org/tip/606424bf4ffd9d27865c45b5707c1edac6b187ed
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Wed, 25 Jun 2025 20:38:32 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 27 Jun 2025 20:13:12 +02:00

timekeeping: Add minimal posix-timers support for auxiliary clocks

Provide clock_getres(2) and clock_gettime(2) for auxiliary clocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.932220594@linutronix.de

---
 kernel/time/posix-timers.c |  3 +++
 kernel/time/posix-timers.h |  1 +
 kernel/time/timekeeping.c  | 21 +++++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 2053b1a..8b58217 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1526,6 +1526,9 @@ static const struct k_clock * const posix_clocks[] = {
 	[CLOCK_REALTIME_ALARM]		= &alarm_clock,
 	[CLOCK_BOOTTIME_ALARM]		= &alarm_clock,
 	[CLOCK_TAI]			= &clock_tai,
+#ifdef CONFIG_POSIX_AUX_CLOCKS
+	[CLOCK_AUX ... CLOCK_AUX_LAST]	= &clock_aux,
+#endif
 };
 
 static const struct k_clock *clockid_to_kclock(const clockid_t id)
diff --git a/kernel/time/posix-timers.h b/kernel/time/posix-timers.h
index 61906f0..7f259e8 100644
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -41,6 +41,7 @@ extern const struct k_clock clock_posix_dynamic;
 extern const struct k_clock clock_process;
 extern const struct k_clock clock_thread;
 extern const struct k_clock alarm_clock;
+extern const struct k_clock clock_aux;
 
 void posix_timer_queue_signal(struct k_itimer *timr);
 
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index c7d2913..10c6e37 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2655,6 +2655,7 @@ EXPORT_SYMBOL(hardpps);
 #endif /* CONFIG_NTP_PPS */
 
 #ifdef CONFIG_POSIX_AUX_CLOCKS
+#include "posix-timers.h"
 
 /*
  * Bitmap for the activated auxiliary timekeepers to allow lockless quick
@@ -2749,6 +2750,26 @@ bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *ts)
 }
 EXPORT_SYMBOL_GPL(ktime_get_aux_ts64);
 
+static int aux_get_res(clockid_t id, struct timespec64 *tp)
+{
+	if (!clockid_aux_valid(id))
+		return -ENODEV;
+
+	tp->tv_sec = 0;
+	tp->tv_nsec = 1;
+	return 0;
+}
+
+static int aux_get_timespec(clockid_t id, struct timespec64 *tp)
+{
+	return ktime_get_aux_ts64(id, tp) ? 0 : -ENODEV;
+}
+
+const struct k_clock clock_aux = {
+	.clock_getres		= aux_get_res,
+	.clock_get_timespec	= aux_get_timespec,
+};
+
 static __init void tk_aux_setup(void)
 {
 	for (int i = TIMEKEEPER_AUX_FIRST; i <= TIMEKEEPER_AUX_LAST; i++)