File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/drivers/rtc/systohc.c b/drivers/rtc/systohc.c
new file mode 100644
index 0000000..b4a68ff
--- /dev/null
+++ b/drivers/rtc/systohc.c
@@ -0,0 +1,47 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ */
+#include <linux/rtc.h>
+#include <linux/time.h>
+
+/**
+ * rtc_set_ntp_time - Save NTP synchronized time to the RTC
+ * @now: Current time of day
+ *
+ * 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.
+ *
+ * If temporary failure is indicated the caller should try again 'soon'
+ */
+int rtc_set_ntp_time(struct timespec64 now)
+{
+ struct rtc_device *rtc;
+ struct rtc_time tm;
+ int err = -ENODEV;
+
+ if (now.tv_nsec < (NSEC_PER_SEC >> 1))
+ rtc_time64_to_tm(now.tv_sec, &tm);
+ else
+ rtc_time64_to_tm(now.tv_sec + 1, &tm);
+
+ rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
+ if (rtc) {
+ /* rtc_hctosys exclusively uses UTC, so we call set_time here,
+ * not set_mmss. */
+ if (rtc->ops &&
+ (rtc->ops->set_time ||
+ rtc->ops->set_mmss64 ||
+ rtc->ops->set_mmss))
+ err = rtc_set_time(rtc, &tm);
+ rtc_class_close(rtc);
+ }
+
+ return err;
+}