OvmfPkg/PciHostBridgeLib: Extract GetRootBridges() / FreeRootBridges()

Extract PciHostBridgeGetRootBridges() / PciHostBridgeFreeRootBridges() to
PciHostBridgeUtilityLib as common utility functions to share support for
scanning extra root bridges.

No change of functionality.

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3059

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
Signed-off-by: Yubo Miao <miaoyubo@huawei.com>
Message-Id: <20210119011302.10908-8-cenjiahui@huawei.com>
[lersek@redhat.com: keep zeroing of (*Count) centralized]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/Include/Library/PciHostBridgeUtilityLib.h

@@ -99,6 +99,56 @@ PciHostBridgeUtilityUninitRootBridge (
   );
 
 
+/**
+  Utility function to return all the root bridge instances in an array.
+
+  @param[out] Count            The number of root bridge instances.
+
+  @param[in]  Attributes       Initial attributes.
+
+  @param[in]  AllocAttributes  Allocation attributes.
+
+  @param[in]  Io               IO aperture.
+
+  @param[in]  Mem              MMIO aperture.
+
+  @param[in]  MemAbove4G       MMIO aperture above 4G.
+
+  @param[in]  PMem             Prefetchable MMIO aperture.
+
+  @param[in]  PMemAbove4G      Prefetchable MMIO aperture above 4G.
+
+  @return                      All the root bridge instances in an array.
+**/
+PCI_ROOT_BRIDGE *
+EFIAPI
+PciHostBridgeUtilityGetRootBridges (
+  OUT UINTN                    *Count,
+  IN  UINT64                   Attributes,
+  IN  UINT64                   AllocationAttributes,
+  IN  PCI_ROOT_BRIDGE_APERTURE *Io,
+  IN  PCI_ROOT_BRIDGE_APERTURE *Mem,
+  IN  PCI_ROOT_BRIDGE_APERTURE *MemAbove4G,
+  IN  PCI_ROOT_BRIDGE_APERTURE *PMem,
+  IN  PCI_ROOT_BRIDGE_APERTURE *PMemAbove4G
+  );
+
+
+/**
+  Utility function to free root bridge instances array from
+  PciHostBridgeUtilityGetRootBridges().
+
+  @param[in] Bridges  The root bridge instances array.
+  @param[in] Count    The count of the array.
+**/
+VOID
+EFIAPI
+PciHostBridgeUtilityFreeRootBridges (
+  IN PCI_ROOT_BRIDGE *Bridges,
+  IN UINTN           Count
+  );
+
+
 /**
   Utility function to inform the platform that the resource conflict happens.