Merge tag 'v4.15-rc1' into next-seccomp

Linux 4.15-rc1

1 files changed, 43 insertions, 3 deletions

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 0a0f0d14a5fb..41319a2e409b 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Generic RTC interface.
  * This version contains the part of the user interface to the Real Time Clock
@@ -72,8 +73,6 @@ extern struct class *rtc_class;
  * issued through ioctl() ...
  */
 struct rtc_class_ops {
-	int (*open)(struct device *);
-	void (*release)(struct device *);
 	int (*ioctl)(struct device *, unsigned int, unsigned long);
 	int (*read_time)(struct device *, struct rtc_time *);
 	int (*set_time)(struct device *, struct rtc_time *);
@@ -137,6 +136,14 @@ struct rtc_device {
 	/* Some hardware can't support UIE mode */
 	int uie_unsupported;
 
+	/* Number of nsec it takes to set the RTC clock. This influences when
+	 * the set ops are called. An offset:
+	 *   - of 0.5 s will call RTC set for wall clock time 10.0 s at 9.5 s
+	 *   - of 1.5 s will call RTC set for wall clock time 10.0 s at 8.5 s
+	 *   - of -0.5 s will call RTC set for wall clock time 10.0 s at 10.5 s
+	 */
+	long set_offset_nsec;
+
 	bool registered;
 
 	struct nvmem_config *nvmem_config;
@@ -174,7 +181,7 @@ extern void devm_rtc_device_unregister(struct device *dev,
 
 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);
+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);
@@ -223,6 +230,39 @@ 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)