diff --git a/common/skylake/hw-gfx-gma-plls.ads b/common/skylake/hw-gfx-gma-plls.ads
new file mode 100644
index 0000000..9407af0
--- /dev/null
+++ b/common/skylake/hw-gfx-gma-plls.ads
@@ -0,0 +1,42 @@
+--
+-- 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.GFX.GMA.PLLs
+with
+   Abstract_State => (State with Part_Of => GMA.State)
+is
+
+   -- NOTE: Order of DPLLs is twisted, as DPLL2 (WRPLL1)
+   --       should be selected as last choice.
+
+   -- XXX: Types should be private (but that triggers a bug in SPARK GPL 2016)
+   type T is (Invalid_PLL, DPLL0, DPLL1, DPLL3, DPLL2);
+   subtype Configurable_DPLLs is T range DPLL1 .. DPLL2;
+   Invalid : constant T := Invalid_PLL;
+
+   procedure Initialize
+   with
+      Global => (Output => State);
+
+   procedure Alloc
+     (Port_Cfg : in     Port_Config;
+      PLL      :    out T;
+      Success  :    out Boolean);
+
+   procedure Free (PLL : T);
+
+   procedure All_Off;
+
+   function Register_Value (PLL : T) return Word32;
+
+end HW.GFX.GMA.PLLs;