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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 kernel/time/posix-timers.c |    3 +++
 kernel/time/posix-timers.h |    1 +
 kernel/time/timekeeping.c  |   21 +++++++++++++++++++++
 3 files changed, 25 insertions(+)
---
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1526,6 +1526,9 @@ static const struct k_clock * const posi
 	[CLOCK_REALTIME_ALARM]		= &alarm_clock,
 	[CLOCK_BOOTTIME_ALARM]		= &alarm_clock,
 	[CLOCK_TAI]			= &clock_tai,
+#ifdef CONFIG_POSIX_PTP_CLOCKS
+	[CLOCK_PTP ... CLOCK_PTP_LAST]	= &clock_ptp,
+#endif
 };
 
 static const struct k_clock *clockid_to_kclock(const clockid_t id)
--- a/kernel/time/posix-timers.h
+++ b/kernel/time/posix-timers.h
@@ -41,6 +41,7 @@ extern const struct k_clock clock_posix_
 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_ptp;
 
 void posix_timer_queue_signal(struct k_itimer *timr);
 
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2655,6 +2655,7 @@ EXPORT_SYMBOL(hardpps);
 #endif /* CONFIG_NTP_PPS */
 
 #ifdef CONFIG_POSIX_PTP_CLOCKS
+#include "posix-timers.h"
 
 /* Bitmap for the activated PTP timekeepers */
 static unsigned long ptp_timekeepers;
@@ -2741,6 +2742,26 @@ bool ktime_get_ptp_ts64(clockid_t id, st
 	return true;
 }
 
+static int ptp_get_res(clockid_t id, struct timespec64 *tp)
+{
+	if (!ptp_valid_clockid(id))
+		return -ENODEV;
+
+	tp->tv_sec = 0;
+	tp->tv_nsec = 1;
+	return 0;
+}
+
+static int ptp_get_timespec(clockid_t id, struct timespec64 *tp)
+{
+	return ktime_get_ptp_ts64(id, tp) ? 0 : -ENODEV;
+}
+
+const struct k_clock clock_ptp = {
+	.clock_getres		= ptp_get_res,
+	.clock_get_timespec	= ptp_get_timespec,
+};
+
 static __init void tk_ptp_setup(void)
 {
 	for (int i = TIMEKEEPER_PTP; i <= TIMEKEEPER_PTP_LAST; i++)