OvmfPkg/XenBusDxe: Open PciIo protocol.

The PciIo interface will be used in "OvmfPkg/XenBusDxe: Add Grant Table
functions" to get the memory address of the BAR 1 and use the space to
map shared memory.

Change in V3:
- add a commit description.

Change in V2:
- Coding style
- Error handler

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16261 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/XenBusDxe/XenBusDxe.c

@@ -281,11 +281,25 @@ XenBusDxeDriverBindingStart (
 {
   EFI_STATUS Status;
   XENBUS_DEVICE *Dev;
+  EFI_PCI_IO_PROTOCOL *PciIo;
+
+  Status = gBS->OpenProtocol (
+                     ControllerHandle,
+                     &gEfiPciIoProtocolGuid,
+                     (VOID **) &PciIo,
+                     This->DriverBindingHandle,
+                     ControllerHandle,
+                     EFI_OPEN_PROTOCOL_BY_DRIVER
+                     );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
   Dev = AllocateZeroPool (sizeof (*Dev));
   Dev->Signature = XENBUS_DEVICE_SIGNATURE;
   Dev->This = This;
   Dev->ControllerHandle = ControllerHandle;
+  Dev->PciIo = PciIo;
 
   EfiAcquireLock (&mMyDeviceLock);
   if (mMyDevice != NULL) {
@@ -323,6 +337,8 @@ XenBusDxeDriverBindingStart (
 
 ErrorAllocated:
   FreePool (Dev);
+  gBS->CloseProtocol (ControllerHandle, &gEfiPciIoProtocolGuid,
+                      This->DriverBindingHandle, ControllerHandle);
   return Status;
 }
 
@@ -365,6 +381,9 @@ XenBusDxeDriverBindingStop (
 
   gBS->CloseEvent (Dev->ExitBootEvent);
 
+  gBS->CloseProtocol (ControllerHandle, &gEfiPciIoProtocolGuid,
+         This->DriverBindingHandle, ControllerHandle);
+
   mMyDevice = NULL;
   FreePool (Dev);
   return EFI_SUCCESS;

OvmfPkg/XenBusDxe/XenBusDxe.h

@@ -84,6 +84,7 @@ struct _XENBUS_DEVICE {
   UINT32                        Signature;
   EFI_DRIVER_BINDING_PROTOCOL   *This;
   EFI_HANDLE                    ControllerHandle;
+  EFI_PCI_IO_PROTOCOL           *PciIo;
   EFI_EVENT                     ExitBootEvent;
 
   VOID                          *Hyperpage;