rtc: Add a generic rtc cache

Some of the generic skiboot code needs access to the rtc (for example
the pel logging code). Currently this is accessed via a call to fsp
specific code which implements an rtc cache. Obviously this wont work
on systems without a fsp.

This patch makes the rtc cache generic so that we can get the time on
other platforms (assuming they have some kind of rtc).

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/core/rtc.c b/core/rtc.c
new file mode 100644
index 0000000..60d2d85
--- /dev/null
+++ b/core/rtc.c
@@ -0,0 +1,69 @@
+/* Copyright 2013-2014 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+#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)
+		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;
+}