Urgh, and now actually add the files :-)

kern/generic/rtc_get_time_ms.c

@@ -0,0 +1,37 @@
+/* rtc_get_time_ms.c - get_time_ms implementation using platform RTC.
+ * The generic implementation of these functions can be used for architectures
+ * or platforms that do not have a more specialized implementation. */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/time.h>
+#include <grub/misc.h>
+
+/* Calculate the time in milliseconds since the epoch based on the RTC. */
+grub_uint64_t
+grub_rtc_get_time_ms (void)
+{
+  /* By dimensional analysis: 
+    
+      1000 ms   N rtc ticks       1 s
+      ------- * ----------- * ----------- = 1000*N/T ms
+        1 s          1        T rtc ticks
+   */
+  grub_uint64_t ticks_ms_per_sec = ((grub_uint64_t) 1000) * grub_get_rtc ();
+  return grub_divmod64 (ticks_ms_per_sec, GRUB_TICKS_PER_SECOND, 0);
+}