From 9aebde8af6fe247d92816c197badf7e236c8f037 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@kernel.org>
Date: Fri, 29 May 2026 22:01:21 +0200
Subject: [PATCH] timekeeping: Add support for AUX clock cross timestamping
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Now that all prerequisites are in place add the final support for AUX
clocks in get_device_system_crosststamp(), which enables the PTP layer to
support hardware cross timestamps with a new IOTCL.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195558.097464513@kernel.org
---
 kernel/time/timekeeping.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index dae61c9e31e6..65d870c2d40d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1517,6 +1517,12 @@ int get_device_system_crosststamp(int (*get_time_fn)
 		tkd = &tk_core;
 		offs = &tk_core.timekeeper.offs_real;
 		break;
+	case CLOCK_AUX ... CLOCK_AUX_LAST:
+		tkd = aux_get_tk_data(xtstamp->clock_id);
+		if (!tkd)
+			return -ENODEV;
+		offs = &tkd->timekeeper.offs_aux;
+		break;
 	default:
 		WARN_ON_ONCE(1);
 		return -ENODEV;