diff --git a/common/skylake/hw-gfx-gma-plls.adb b/common/skylake/hw-gfx-gma-plls.adb
new file mode 100644
index 0000000..561f8ad
--- /dev/null
+++ b/common/skylake/hw-gfx-gma-plls.adb
@@ -0,0 +1,151 @@
+--
+-- 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.
+--
+
+with HW.GFX.GMA.PLLs.DPLL_0;
+with HW.GFX.GMA.PLLs.DPLL;
+
+with HW.Debug;
+with GNAT.Source_Info;
+
+package body HW.GFX.GMA.PLLs
+with
+   Refined_State => (State => PLLs)
+is
+
+   type Count_Range is new Natural range 0 .. 2;
+
+   type PLL_State is record
+      Use_Count   : Count_Range;
+      Used_For_DP : Boolean;
+      Link_Rate   : DP_Bandwidth;
+      Mode        : Mode_Type;
+   end record;
+
+   type PLL_State_Array is array (Configurable_DPLLs) of PLL_State;
+
+   PLLs : PLL_State_Array;
+
+   procedure Initialize
+   is
+   begin
+      PLLs :=
+        (Configurable_DPLLs =>
+           (Use_Count   => 0,
+            Used_For_DP => False,
+            Link_Rate   => DP_Bandwidth'First,
+            Mode        => Invalid_Mode));
+   end Initialize;
+
+   procedure Alloc_Configurable
+     (Port_Cfg : in     Port_Config;
+      PLL      :    out T;
+      Success  :    out Boolean)
+   with
+      Pre => True
+   is
+      function Config_Matches (PE : PLL_State) return Boolean
+      is
+      begin
+         return
+            PE.Used_For_DP = (Port_Cfg.Display = DP) and
+            ((PE.Used_For_DP and PE.Link_Rate = Port_Cfg.DP.Bandwidth) or
+             (not PE.Used_For_DP and PE.Mode = Port_Cfg.Mode));
+      end Config_Matches;
+   begin
+      -- try to find shareable PLL
+      for P in Configurable_DPLLs loop
+         Success := PLLs (P).Use_Count /= 0 and
+                     PLLs (P).Use_Count /= Count_Range'Last and
+                     Config_Matches (PLLs (P));
+         if Success then
+            PLL := P;
+            PLLs (PLL).Use_Count := PLLs (PLL).Use_Count + 1;
+            return;
+         end if;
+      end loop;
+
+      -- try to find free PLL
+      for P in Configurable_DPLLs loop
+         if PLLs (P).Use_Count = 0 then
+            PLL := P;
+            DPLL.On (PLL, Port_Cfg, Success);
+            if Success then
+               PLLs (PLL) :=
+                 (Use_Count   => 1,
+                  Used_For_DP => Port_Cfg.Display = DP,
+                  Link_Rate   => Port_Cfg.DP.Bandwidth,
+                  Mode        => Port_Cfg.Mode);
+            end if;
+            return;
+         end if;
+      end loop;
+
+      PLL := Invalid;
+   end Alloc_Configurable;
+
+   procedure Alloc
+     (Port_Cfg : in     Port_Config;
+      PLL      :    out T;
+      Success  :    out Boolean)
+   is
+   begin
+      pragma Debug (Debug.Put_Line (GNAT.Source_Info.Enclosing_Entity));
+
+      if Port_Cfg.Port = DIGI_A then
+         DPLL_0.Check_Link_Rate (Port_Cfg.DP.Bandwidth, Success);
+      else
+         Success := False;
+      end if;
+
+      if Success then
+         PLL := DPLL0;
+      else
+         Alloc_Configurable (Port_Cfg, PLL, Success);
+      end if;
+   end Alloc;
+
+   procedure Free (PLL : T)
+   is
+   begin
+      pragma Debug (Debug.Put_Line (GNAT.Source_Info.Enclosing_Entity));
+
+      if PLL in Configurable_DPLLs then
+         if PLLs (PLL).Use_Count /= 0 then
+            PLLs (PLL).Use_Count := PLLs (PLL).Use_Count - 1;
+            if PLLs (PLL).Use_Count = 0 then
+               DPLL.Off (PLL);
+            end if;
+         end if;
+      end if;
+   end Free;
+
+   procedure All_Off
+   is
+   begin
+      pragma Debug (Debug.Put_Line (GNAT.Source_Info.Enclosing_Entity));
+
+      for PLL in Configurable_DPLLs loop
+         DPLL.Off (PLL);
+      end loop;
+   end All_Off;
+
+   function Register_Value (PLL : T) return Word32
+   is
+   begin
+      return
+        (if    PLL = DPLL0                then DPLL_0.Register_Value
+         elsif PLL in Configurable_DPLLs  then DPLL.Register_Value (PLL)
+         else 0);
+   end Register_Value;
+
+end HW.GFX.GMA.PLLs;