From 7543e714c15891aeca6588efc8700358af3d0d9c Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Fri, 7 Aug 2020 13:19:16 +0200
Subject: [PATCH] drivers/periph_common: RTC: move RIOT_EPOCH to header,
 document it.

---
 drivers/include/periph/rtc.h | 12 ++++++++++++
 drivers/periph_common/rtc.c  |  4 ----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/include/periph/rtc.h b/drivers/include/periph/rtc.h
index 4885996be9..5c21822ce1 100644
--- a/drivers/include/periph/rtc.h
+++ b/drivers/include/periph/rtc.h
@@ -46,6 +46,18 @@
 extern "C" {
 #endif
 
+#if !defined(RIOT_EPOCH) || DOXYGEN
+/**
+ * @brief Earliest year of the RTC
+ *
+ * 01.01.$RIOT_EPOCH will be the reset value of the RTC if supported.
+ *
+ * Internal RTC helper functions such as @see rtc_mktime and @see rtc_localtime
+ * will not work on dates earlier than that.
+ */
+#define RIOT_EPOCH (2020)
+#endif
+
 /**
  * @brief Signature for alarm Callback
  *
diff --git a/drivers/periph_common/rtc.c b/drivers/periph_common/rtc.c
index 3968c3aec8..e12dce5d94 100644
--- a/drivers/periph_common/rtc.c
+++ b/drivers/periph_common/rtc.c
@@ -31,10 +31,6 @@
 #define HOUR    (60U * MINUTE)
 #define DAY     (24U * HOUR)
 
-#ifndef RIOT_EPOCH
-#define RIOT_EPOCH (2020)
-#endif
-
 /*
  * The rules here are (to be checked in that explicit order):
  *  1. If the year is not a multiple of four, it is not a leap year.