1 files changed, 137 insertions, 0 deletions
diff --git a/OvmfPkg/RiscVVirt/Library/VirtNorFlashPlatformLib/VirtNorFlashDeviceTreeLib.c b/OvmfPkg/RiscVVirt/Library/VirtNorFlashPlatformLib/VirtNorFlashDeviceTreeLib.c
new file mode 100644
index 0000000000..73534a8664
--- /dev/null
+++ b/OvmfPkg/RiscVVirt/Library/VirtNorFlashPlatformLib/VirtNorFlashDeviceTreeLib.c
@@ -0,0 +1,137 @@
+/** @file
+
+ Copyright (c) 2014-2018, Linaro Ltd. All rights reserved.<BR>
+ Copyright (c) 2023, Ventana Micro Systems Inc. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+ **/
+
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/VirtNorFlashPlatformLib.h>
+
+#include <Protocol/FdtClient.h>
+
+#define QEMU_NOR_BLOCK_SIZE  SIZE_256KB
+
+#define MAX_FLASH_BANKS  4
+
+EFI_STATUS
+VirtNorFlashPlatformInitialization (
+  VOID
+  )
+{
+  return EFI_SUCCESS;
+}
+
+STATIC VIRT_NOR_FLASH_DESCRIPTION  mNorFlashDevices[MAX_FLASH_BANKS];
+
+EFI_STATUS
+VirtNorFlashPlatformGetDevices (
+  OUT VIRT_NOR_FLASH_DESCRIPTION  **NorFlashDescriptions,
+  OUT UINT32                      *Count
+  )
+{
+  FDT_CLIENT_PROTOCOL  *FdtClient;
+  INT32                Node;
+  EFI_STATUS           Status;
+  EFI_STATUS           FindNodeStatus;
+  CONST UINT32         *Reg;
+  UINT32               PropSize;
+  UINT32               Num;
+  UINT64               Base;
+  UINT64               Size;
+
+  Status = gBS->LocateProtocol (
+                  &gFdtClientProtocolGuid,
+                  NULL,
+                  (VOID **)&FdtClient
+                  );
+  ASSERT_EFI_ERROR (Status);
+
+  Num = 0;
+  for (FindNodeStatus = FdtClient->FindCompatibleNode (
+                                     FdtClient,
+                                     "cfi-flash",
+                                     &Node
+                                     );
+       !EFI_ERROR (FindNodeStatus) && Num < MAX_FLASH_BANKS;
+       FindNodeStatus = FdtClient->FindNextCompatibleNode (
+                                     FdtClient,
+                                     "cfi-flash",
+                                     Node,
+                                     &Node
+                                     ))
+  {
+    Status = FdtClient->GetNodeProperty (
+                          FdtClient,
+                          Node,
+                          "reg",
+                          (CONST VOID **)&Reg,
+                          &PropSize
+                          );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "%a: GetNodeProperty () failed (Status == %r)\n",
+        __func__,
+        Status
+        ));
+      continue;
+    }
+
+    ASSERT ((PropSize % (4 * sizeof (UINT32))) == 0);
+
+    while (PropSize >= (4 * sizeof (UINT32)) && Num < MAX_FLASH_BANKS) {
+      Base = SwapBytes64 (ReadUnaligned64 ((VOID *)&Reg[0]));
+      Size = SwapBytes64 (ReadUnaligned64 ((VOID *)&Reg[2]));
+      Reg += 4;
+
+      PropSize -= 4 * sizeof (UINT32);
+
+      //
+      // Disregard any flash devices that overlap with the primary FV.
+      // The firmware is not updatable from inside the guest anyway.
+      //
+      if ((PcdGet32 (PcdOvmfFdBaseAddress) + PcdGet32 (PcdOvmfFirmwareFdSize) > Base) &&
+          ((Base + Size) > PcdGet32 (PcdOvmfFdBaseAddress)))
+      {
+        continue;
+      }
+
+      mNorFlashDevices[Num].DeviceBaseAddress = (UINTN)Base;
+      mNorFlashDevices[Num].RegionBaseAddress = (UINTN)Base;
+      mNorFlashDevices[Num].Size              = (UINTN)Size;
+      mNorFlashDevices[Num].BlockSize         = QEMU_NOR_BLOCK_SIZE;
+      Num++;
+    }
+
+    //
+    // UEFI takes ownership of the NOR flash, and exposes its functionality
+    // through the UEFI Runtime Services GetVariable, SetVariable, etc. This
+    // means we need to disable it in the device tree to prevent the OS from
+    // attaching its device driver as well.
+    // Note that this also hides other flash banks, but the only other flash
+    // bank we expect to encounter is the one that carries the UEFI executable
+    // code, which is not intended to be guest updatable, and is usually backed
+    // in a readonly manner by QEMU anyway.
+    //
+    Status = FdtClient->SetNodeProperty (
+                          FdtClient,
+                          Node,
+                          "status",
+                          "disabled",
+                          sizeof ("disabled")
+                          );
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_WARN, "Failed to set NOR flash status to 'disabled'\n"));
+    }
+  }
+
+  *NorFlashDescriptions = mNorFlashDevices;
+  *Count                = Num;
+
+  return EFI_SUCCESS;
+}