diff --git a/common/hw-gfx-gma-pch.ads b/common/hw-gfx-gma-pch.ads
new file mode 100644
index 0000000..5826c1d
--- /dev/null
+++ b/common/hw-gfx-gma-pch.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.
+--
+
+with HW.GFX.GMA.Config;
+
+private package HW.GFX.GMA.PCH is
+
+   type FDI_Port_Type is (FDI_A, FDI_B, FDI_C);
+
+   ----------------------------------------------------------------------------
+
+   -- common to all PCH outputs
+
+   PCH_TRANSCODER_SELECT_SHIFT : constant :=
+     (case Config.CPU is
+         when Ironlake                       => 30,
+         when Sandybridge | Ivybridge        => 29,
+         when Haswell | Broadwell | Skylake  =>  0);
+
+   PCH_TRANSCODER_SELECT_MASK : constant :=
+     (case Config.CPU is
+         when Ironlake                       => 1 * 2 ** 30,
+         when Sandybridge | Ivybridge        => 3 * 2 ** 29,
+         when Haswell | Broadwell | Skylake  =>           0);
+
+   type PCH_TRANSCODER_SELECT_Array is array (FDI_Port_Type) of Word32;
+   PCH_TRANSCODER_SELECT : constant PCH_TRANSCODER_SELECT_Array :=
+     (FDI_A => 0 * 2 ** PCH_TRANSCODER_SELECT_SHIFT,
+      FDI_B => 1 * 2 ** PCH_TRANSCODER_SELECT_SHIFT,
+      FDI_C => 2 * 2 ** PCH_TRANSCODER_SELECT_SHIFT);
+
+end HW.GFX.GMA.PCH;