MdeModulePkg PciBusDxe: Follow the P2P Bridge spec to detect if a P2P bridge supports...

Signed-off-by: rsun3
Reviewed-by: mdkinney
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12975 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
index ccec37b2870cf29766d0b1bc27e3bd98e06a53f5..7dfa93391861638fcc298509f90f5f6c79598201 100644 (file)
--- a/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
+++ b/MdeModulePkg/Bus/Pci/PciBusDxe/PciEnumeratorSupport.c
@@ -1,7 +1,7 @@
 /** @file\r
   PCI emumeration support functions implementation for PCI Bus module.\r
 \r
-Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
+Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>\r
 This program and the accompanying materials\r
 are licensed and made available under the terms and conditions of the BSD License\r
 which accompanies this distribution.  The full text of the license may be found at\r
@@ -459,6 +459,9 @@ GatherPpbInfo (
   UINT8                           Value;\r
   EFI_PCI_IO_PROTOCOL             *PciIo;\r
   UINT8                           Temp;\r
+  UINT32                          PMemBaseLimit;\r
+  UINT16                          PrefetchableMemoryBase;\r
+  UINT16                          PrefetchableMemoryLimit;\r
 \r
   PciIoDevice = CreatePciIoDevice (\r
                   Bridge,\r
@@ -552,14 +555,22 @@ GatherPpbInfo (
             PciIoDevice,\r
             0x24,\r
             NULL,\r
-            NULL\r
+            &PMemBaseLimit\r
             );\r
 \r
   //\r
   // Test if it supports 64 memory or not\r
   //\r
-  if (!EFI_ERROR (Status)) {\r
-\r
+  // The bottom 4 bits of both the Prefetchable Memory Base and Prefetchable Memory Limit\r
+  // registers:\r
+  //   0 - the bridge supports only 32 bit addresses.\r
+  //   1 - the bridge supports 64-bit addresses.\r
+  //\r
+  PrefetchableMemoryBase = PMemBaseLimit & 0xffff;\r
+  PrefetchableMemoryLimit = PMemBaseLimit >> 16;\r
+  if (!EFI_ERROR (Status) &&\r
+      (PrefetchableMemoryBase & 0x000f) == 0x0001 &&\r
+      (PrefetchableMemoryLimit & 0x000f) == 0x0001) {\r
     Status = BarExisted (\r
               PciIoDevice,\r
               0x28,\r