actually add kern/time.c

kern/time.c

@@ -0,0 +1,37 @@
+/* time.c - kernel time functions */
+/*
+ *  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>
+
+typedef grub_uint64_t (*get_time_ms_func_t) (void);
+
+/* Function pointer to the implementation in use.  */
+static get_time_ms_func_t get_time_ms_func;
+
+grub_uint64_t
+grub_get_time_ms (void)
+{
+  return get_time_ms_func ();
+}
+
+void
+grub_install_get_time_ms (get_time_ms_func_t func)
+{
+  get_time_ms_func = func;
+}