diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 6b611fe5a95e..4ca5a464a46a 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -325,13 +325,22 @@ static long ptp_sys_offset_extended(struct ptp_clock *ptp, void __user *arg)
 	if (IS_ERR(extoff))
 		return PTR_ERR(extoff);
 
-	if (extoff->n_samples > PTP_MAX_SAMPLES ||
-	    extoff->rsv[0] || extoff->rsv[1] ||
-	    (extoff->clockid != CLOCK_REALTIME &&
-	     extoff->clockid != CLOCK_MONOTONIC &&
-	     extoff->clockid != CLOCK_MONOTONIC_RAW))
+	if (extoff->n_samples > PTP_MAX_SAMPLES || extoff->rsv[0] || extoff->rsv[1])
 		return -EINVAL;
 
+	switch (extoff->clockid) {
+	case CLOCK_REALTIME:
+	case CLOCK_MONOTONIC:
+	case CLOCK_MONOTONIC_RAW:
+		break;
+	case CLOCK_AUX ... CLOCK_AUX_LAST:
+		if (IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS))
+			break;
+		fallthrough;
+	default:
+		return -EINVAL;
+	}
+
 	sts.clockid = extoff->clockid;
 	for (unsigned int i = 0; i < extoff->n_samples; i++) {
 		struct timespec64 ts;
@@ -340,6 +349,11 @@ static long ptp_sys_offset_extended(struct ptp_clock *ptp, void __user *arg)
 		err = ptp->info->gettimex64(ptp->info, &ts, &sts);
 		if (err)
 			return err;
+
+		/* Filter out disabled or unavailable clocks */
+		if (sts.pre_ts.tv_sec < 0 || sts.post_ts.tv_sec < 0)
+			return -EINVAL;
+
 		extoff->ts[i][0].sec = sts.pre_ts.tv_sec;
 		extoff->ts[i][0].nsec = sts.pre_ts.tv_nsec;
 		extoff->ts[i][1].sec = ts.tv_sec;
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index eced7e9bf69a..3d089bd4d5e9 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -477,40 +477,14 @@ static inline ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp,
 
 static inline void ptp_read_system_prets(struct ptp_system_timestamp *sts)
 {
-	if (sts) {
-		switch (sts->clockid) {
-		case CLOCK_REALTIME:
-			ktime_get_real_ts64(&sts->pre_ts);
-			break;
-		case CLOCK_MONOTONIC:
-			ktime_get_ts64(&sts->pre_ts);
-			break;
-		case CLOCK_MONOTONIC_RAW:
-			ktime_get_raw_ts64(&sts->pre_ts);
-			break;
-		default:
-			break;
-		}
-	}
+	if (sts)
+		ktime_get_clock_ts64(sts->clockid, &sts->pre_ts);
 }
 
 static inline void ptp_read_system_postts(struct ptp_system_timestamp *sts)
 {
-	if (sts) {
-		switch (sts->clockid) {
-		case CLOCK_REALTIME:
-			ktime_get_real_ts64(&sts->post_ts);
-			break;
-		case CLOCK_MONOTONIC:
-			ktime_get_ts64(&sts->post_ts);
-			break;
-		case CLOCK_MONOTONIC_RAW:
-			ktime_get_raw_ts64(&sts->post_ts);
-			break;
-		default:
-			break;
-		}
-	}
+	if (sts)
+		ktime_get_clock_ts64(sts->clockid, &sts->post_ts);
 }
 
 #endif