ntp, rtc: Move rtc_set_ntp_time() to ntp code

rtc_set_ntp_time() is not really RTC functionality as the code is just a
user of RTC. Move it into the NTP code which allows further cleanups.
Requested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201206220542.166871172@linutronix.de

drivers/rtc/Makefile

@@ -6,7 +6,6 @@
 ccflags-$(CONFIG_RTC_DEBUG)	:= -DDEBUG
 
 obj-$(CONFIG_RTC_LIB)		+= lib.o
-obj-$(CONFIG_RTC_SYSTOHC)	+= systohc.o
 obj-$(CONFIG_RTC_CLASS)		+= rtc-core.o
 obj-$(CONFIG_RTC_MC146818_LIB)	+= rtc-mc146818-lib.o
 rtc-core-y			:= class.o interface.o

drivers/rtc/systohc.c

-// SPDX-License-Identifier: GPL-2.0
-#include <linux/rtc.h>
-#include <linux/time.h>
-
-/**
- * rtc_set_ntp_time - Save NTP synchronized time to the RTC
- * @now: Current time of day
- * @target_nsec: pointer for desired now->tv_nsec value
- *
- * Replacement for the NTP platform function update_persistent_clock64
- * that stores time for later retrieval by rtc_hctosys.
- *
- * Returns 0 on successful RTC update, -ENODEV if a RTC update is not
- * possible at all, and various other -errno for specific temporary failure
- * cases.
- *
- * -EPROTO is returned if now.tv_nsec is not close enough to *target_nsec.
- *
- * If temporary failure is indicated the caller should try again 'soon'
- */
-int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec)
-{
-	struct rtc_device *rtc;
-	struct rtc_time tm;
-	struct timespec64 to_set;
-	int err = -ENODEV;
-	bool ok;
-
-	rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
-	if (!rtc)
-		goto out_err;
-
-	if (!rtc->ops || !rtc->ops->set_time)
-		goto out_close;
-
-	/* Compute the value of tv_nsec we require the caller to supply in
-	 * now.tv_nsec.  This is the value such that (now +
-	 * set_offset_nsec).tv_nsec == 0.
-	 */
-	set_normalized_timespec64(&to_set, 0, -rtc->set_offset_nsec);
-	*target_nsec = to_set.tv_nsec;
-
-	/* The ntp code must call this with the correct value in tv_nsec, if
-	 * it does not we update target_nsec and return EPROTO to make the ntp
-	 * code try again later.
-	 */
-	ok = rtc_tv_nsec_ok(rtc->set_offset_nsec, &to_set, &now);
-	if (!ok) {
-		err = -EPROTO;
-		goto out_close;
-	}
-
-	rtc_time64_to_tm(to_set.tv_sec, &tm);
-
-	err = rtc_set_time(rtc, &tm);
-
-out_close:
-	rtc_class_close(rtc);
-out_err:
-	return err;
-}

include/linux/rtc.h

@@ -165,7 +165,6 @@ int __rtc_register_device(struct module *owner, struct rtc_device *rtc);
 
 extern int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm);
 extern int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm);
-extern int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec);
 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm);
 extern int rtc_read_alarm(struct rtc_device *rtc,
 			struct rtc_wkalrm *alrm);
@@ -205,39 +204,6 @@ static inline bool is_leap_year(unsigned int year)
 	return (!(year % 4) && (year % 100)) || !(year % 400);
 }
 
-/* Determine if we can call to driver to set the time. Drivers can only be
- * called to set a second aligned time value, and the field set_offset_nsec
- * specifies how far away from the second aligned time to call the driver.
- *
- * This also computes 'to_set' which is the time we are trying to set, and has
- * a zero in tv_nsecs, such that:
- *    to_set - set_delay_nsec == now +/- FUZZ
- *
- */
-static inline bool rtc_tv_nsec_ok(s64 set_offset_nsec,
-				  struct timespec64 *to_set,
-				  const struct timespec64 *now)
-{
-	/* Allowed error in tv_nsec, arbitarily set to 5 jiffies in ns. */
-	const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
-	struct timespec64 delay = {.tv_sec = 0,
-				   .tv_nsec = set_offset_nsec};
-
-	*to_set = timespec64_add(*now, delay);
-
-	if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
-		to_set->tv_nsec = 0;
-		return true;
-	}
-
-	if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
-		to_set->tv_sec++;
-		to_set->tv_nsec = 0;
-		return true;
-	}
-	return false;
-}
-
 #define rtc_register_device(device) \
 	__rtc_register_device(THIS_MODULE, device)
 

kernel/time/ntp.c

@@ -519,15 +519,94 @@ static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry)
 	hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS);
 }
 
+/*
+ * Determine if we can call to driver to set the time. Drivers can only be
+ * called to set a second aligned time value, and the field set_offset_nsec
+ * specifies how far away from the second aligned time to call the driver.
+ *
+ * This also computes 'to_set' which is the time we are trying to set, and has
+ * a zero in tv_nsecs, such that:
+ *    to_set - set_delay_nsec == now +/- FUZZ
+ *
+ */
+static inline bool rtc_tv_nsec_ok(long set_offset_nsec,
+				  struct timespec64 *to_set,
+				  const struct timespec64 *now)
+{
+	/* Allowed error in tv_nsec, arbitarily set to 5 jiffies in ns. */
+	const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
+	struct timespec64 delay = {.tv_sec = 0,
+				   .tv_nsec = set_offset_nsec};
+
+	*to_set = timespec64_add(*now, delay);
+
+	if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
+		to_set->tv_nsec = 0;
+		return true;
+	}
+
+	if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
+		to_set->tv_sec++;
+		to_set->tv_nsec = 0;
+		return true;
+	}
+	return false;
+}
+
+#ifdef CONFIG_RTC_SYSTOHC
+/*
+ * rtc_set_ntp_time - Save NTP synchronized time to the RTC
+ */
+static int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec)
+{
+	struct rtc_device *rtc;
+	struct rtc_time tm;
+	struct timespec64 to_set;
+	int err = -ENODEV;
+	bool ok;
+
+	rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
+	if (!rtc)
+		goto out_err;
+
+	if (!rtc->ops || !rtc->ops->set_time)
+		goto out_close;
+
+	/*
+	 * Compute the value of tv_nsec we require the caller to supply in
+	 * now.tv_nsec.  This is the value such that (now +
+	 * set_offset_nsec).tv_nsec == 0.
+	 */
+	set_normalized_timespec64(&to_set, 0, -rtc->set_offset_nsec);
+	*target_nsec = to_set.tv_nsec;
+
+	/*
+	 * The ntp code must call this with the correct value in tv_nsec, if
+	 * it does not we update target_nsec and return EPROTO to make the ntp
+	 * code try again later.
+	 */
+	ok = rtc_tv_nsec_ok(rtc->set_offset_nsec, &to_set, &now);
+	if (!ok) {
+		err = -EPROTO;
+		goto out_close;
+	}
+
+	rtc_time64_to_tm(to_set.tv_sec, &tm);
+
+	err = rtc_set_time(rtc, &tm);
+
+out_close:
+	rtc_class_close(rtc);
+out_err:
+	return err;
+}
+
 static void sync_rtc_clock(void)
 {
 	unsigned long offset_nsec;
 	struct timespec64 adjust;
 	int rc;
 
-	if (!IS_ENABLED(CONFIG_RTC_SYSTOHC))
-		return;
-
 	ktime_get_real_ts64(&adjust);
 
 	if (persistent_clock_is_local)
@@ -544,6 +623,9 @@ static void sync_rtc_clock(void)
 
 	sched_sync_hw_clock(offset_nsec, rc != 0);
 }
+#else
+static inline void sync_rtc_clock(void) { }
+#endif
 
 #ifdef CONFIG_GENERIC_CMOS_UPDATE
 int __weak update_persistent_clock64(struct timespec64 now64)