1 files changed, 62 insertions, 0 deletions
diff --git a/roms/skiboot/core/rtc.c b/roms/skiboot/core/rtc.c
new file mode 100644
index 000000000..3c0dda71e
--- /dev/null
+++ b/roms/skiboot/core/rtc.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/*
+ * Real Time Clock (RTC) Cache
+ *
+ * Copyright 2013-2014 IBM Corp.
+ */
+
+#include <skiboot.h>
+#include <lock.h>
+#include <rtc.h>
+#include <timebase.h>
+
+static struct lock rtc_tod_lock = LOCK_UNLOCKED;
+
+static struct {
+	struct tm	tm;
+	unsigned long	tb;
+	bool		valid;
+} rtc_tod_cache;
+
+void rtc_cache_update(struct tm *tm)
+{
+	lock(&rtc_tod_lock);
+	rtc_tod_cache.tb = mftb();
+	rtc_tod_cache.tm = *tm;
+	rtc_tod_cache.valid = true;
+	unlock(&rtc_tod_lock);
+}
+
+int rtc_cache_get(struct tm *tm)
+{
+	unsigned long cache_age_sec;
+
+	lock(&rtc_tod_lock);
+
+	if (!rtc_tod_cache.valid) {
+		unlock(&rtc_tod_lock);
+		return -1;
+	}
+
+	cache_age_sec = tb_to_msecs(mftb() - rtc_tod_cache.tb) / 1000;
+	*tm = rtc_tod_cache.tm;
+	unlock(&rtc_tod_lock);
+
+	tm->tm_sec += cache_age_sec;
+	mktime(tm);
+
+	return 0;
+}
+
+int rtc_cache_get_datetime(uint32_t *year_month_day,
+		uint64_t *hour_minute_second_millisecond)
+{
+	struct tm tm;
+
+	if (rtc_cache_get(&tm) < 0)
+		return -1;
+
+	tm_to_datetime(&tm, year_month_day, hour_minute_second_millisecond);
+
+	return 0;
+}