1 files changed, 64 insertions, 0 deletions
diff --git a/roms/skiboot/core/time-utils.c b/roms/skiboot/core/time-utils.c
new file mode 100644
index 000000000..e948654d3
--- /dev/null
+++ b/roms/skiboot/core/time-utils.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/*
+ * Converts an OPAL formatted datetime into a struct tm. We ignore microseconds
+ * as Linux doesn't use them anyway.
+ *
+ *  |      year       | month |   mday   |
+ *  +------------------------------------+
+ *  |  hour  | minute | secs  | reserved |
+ *  +------------------------------------+
+ *  |             microseconds           |
+ *
+ * Copyright 2013-2014 IBM Corp.
+ */
+
+#include <time-utils.h>
+
+void datetime_to_tm(uint32_t y_m_d, uint64_t h_m_s_m, struct tm *tm)
+{
+	uint32_t x;
+
+	tm->tm_year = bcd_byte(y_m_d, 3) * 100 + bcd_byte(y_m_d, 2);
+	tm->tm_mon = bcd_byte(y_m_d, 1) - 1;
+	tm->tm_mday = bcd_byte(y_m_d, 0);
+
+	x = h_m_s_m >> 32;
+	tm->tm_hour = bcd_byte(x, 3);
+	tm->tm_min = bcd_byte(x, 2);
+	tm->tm_sec = bcd_byte(x, 1);
+}
+
+/*
+ * The OPAL API is defined as returned a u64 of a similar
+ * format to the FSP message; the 32-bit date field is
+ * in the format:
+ *
+ * |      year        | month |   mday   |
+ *
+ * ... and the 64-bit time field is in the format
+ *
+ * |  hour  | minutes | secs  | millisec |
+ * | -------------------------------------
+ * |        millisec          | reserved |
+ *
+ * We simply ignore the microseconds/milliseconds for now
+ * as I don't quite understand why the OPAL API defines that
+ * it needs 6 digits for the milliseconds :-) I suspect the
+ * doc got that wrong and it's supposed to be micro but
+ * let's ignore it.
+ *
+ * Note that Linux doesn't use nor set the ms field anyway.
+ */
+void tm_to_datetime(struct tm *tm, uint32_t *y_m_d, uint64_t *h_m_s_m)
+{
+	uint64_t h_m_s;
+	*y_m_d = int_to_bcd4(tm->tm_year) << 16 |
+		 int_to_bcd2(tm->tm_mon + 1) << 8 |
+		 int_to_bcd2(tm->tm_mday);
+
+	h_m_s = int_to_bcd2(tm->tm_hour) << 24 |
+	        int_to_bcd2(tm->tm_min) << 16 |
+	        int_to_bcd2(tm->tm_sec) << 8;
+
+	*h_m_s_m = h_m_s << 32;
+}