diff --git a/common/hw-time-timer.ads b/common/hw-time-timer.ads
new file mode 100644
index 0000000..4676815
--- /dev/null
+++ b/common/hw-time-timer.ads
@@ -0,0 +1,41 @@
+--
+-- Copyright (C) 2015-2016 secunet Security Networks AG
+--
+-- This program 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; version 2 of the License.
+--
+-- This program 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.
+--
+
+private package HW.Time.Timer
+   with
+      Abstract_State => ((Timer_State with Part_Of => HW.Time.State),
+                         (Abstract_Time with
+                           Part_Of => HW.Time.State,
+                           External => Async_Writers)),
+      Initializes => (Timer_State)
+is
+
+   -- Returns the highest point in time that has definitely passed.
+   function Raw_Value_Min return T
+   with
+      Volatile_Function,
+      Global => (Input => Abstract_Time),
+      Depends => (Raw_Value_Min'Result => Abstract_Time);
+
+   -- Returns the highest point in time that might have been reached yet.
+   function Raw_Value_Max return T
+   with
+      Volatile_Function,
+      Global => (Input => Abstract_Time),
+      Depends => (Raw_Value_Max'Result => Abstract_Time);
+
+   function Hz return T
+   with
+      Global => (Input => Timer_State);
+
+end HW.Time.Timer;