From 7b6745cc11084ad7f8900a00c922cc112c405ac5 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Fri, 8 Apr 2016 11:44:58 +0200
Subject: [PATCH] ArmVirtPkg/QemuFwCfgLib: move to FDT client protocol

Make this library depend on the FDT client protocol to access the
host supplied device tree directly rather than depending on VirtFdtDxe
to set them using dynamic PCDs.

Since this library is used by several drivers (BdsDxe, SmbiosPlatformDxe,
SmbiosDxe and QemuFwCfgAcpiPlatformDxe), we will end up parsing the device
tree and the fwcfg node at least four times. However, no dynamic PCDs are
involved anymore, and will even be removed completely in a subsequent
patch. So the conversion is not optimal, but guaranteed to be safe.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
 .../Library/QemuFwCfgLib/QemuFwCfgLib.c       | 76 +++++++++++++++++--
 .../Library/QemuFwCfgLib/QemuFwCfgLib.inf     | 11 +--
 2 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
index 303dc520c6..377262563e 100644
--- a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
+++ b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
@@ -14,12 +14,16 @@
   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 **/
 
+#include <Uefi.h>
+
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 #include <Library/IoLib.h>
-#include <Library/PcdLib.h>
 #include <Library/QemuFwCfgLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+
+#include <Protocol/FdtClient.h>
 
 STATIC UINTN mFwCfgSelectorAddress;
 STATIC UINTN mFwCfgDataAddress;
@@ -115,8 +119,70 @@ QemuFwCfgInitialize (
   VOID
   )
 {
-  mFwCfgSelectorAddress = (UINTN)PcdGet64 (PcdFwCfgSelectorAddress);
-  mFwCfgDataAddress     = (UINTN)PcdGet64 (PcdFwCfgDataAddress);
+  EFI_STATUS                    Status;
+  FDT_CLIENT_PROTOCOL           *FdtClient;
+  CONST UINT64                  *Reg;
+  UINT32                        RegElemSize, RegSize;
+  UINT64                        FwCfgSelectorAddress;
+  UINT64                        FwCfgSelectorSize;
+  UINT64                        FwCfgDataAddress;
+  UINT64                        FwCfgDataSize;
+  UINT64                        FwCfgDmaAddress;
+  UINT64                        FwCfgDmaSize;
+
+  Status = gBS->LocateProtocol (&gFdtClientProtocolGuid, NULL,
+                  (VOID **)&FdtClient);
+  ASSERT_EFI_ERROR (Status);
+
+  Status = FdtClient->FindCompatibleNodeReg (FdtClient, "qemu,fw-cfg-mmio",
+                         (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((EFI_D_WARN,
+      "%a: No 'qemu,fw-cfg-mmio' compatible DT node found (Status == %r)\n",
+      __FUNCTION__, Status));
+    return EFI_SUCCESS;
+  }
+
+  ASSERT (RegElemSize == sizeof (UINT64));
+  ASSERT (RegSize == 2 * sizeof (UINT64));
+
+  FwCfgDataAddress     = SwapBytes64 (Reg[0]);
+  FwCfgDataSize        = 8;
+  FwCfgSelectorAddress = FwCfgDataAddress + FwCfgDataSize;
+  FwCfgSelectorSize    = 2;
+
+  //
+  // The following ASSERT()s express
+  //
+  //   Address + Size - 1 <= MAX_UINTN
+  //
+  // for both registers, that is, that the last byte in each MMIO range is
+  // expressible as a MAX_UINTN. The form below is mathematically
+  // equivalent, and it also prevents any unsigned overflow before the
+  // comparison.
+  //
+  ASSERT (FwCfgSelectorAddress <= MAX_UINTN - FwCfgSelectorSize + 1);
+  ASSERT (FwCfgDataAddress     <= MAX_UINTN - FwCfgDataSize     + 1);
+
+  mFwCfgSelectorAddress = FwCfgSelectorAddress;
+  mFwCfgDataAddress     = FwCfgDataAddress;
+
+  DEBUG ((EFI_D_INFO, "Found FwCfg @ 0x%Lx/0x%Lx\n", FwCfgSelectorAddress,
+    FwCfgDataAddress));
+
+  if (SwapBytes64 (Reg[1]) >= 0x18) {
+    FwCfgDmaAddress = FwCfgDataAddress + 0x10;
+    FwCfgDmaSize    = 0x08;
+
+    //
+    // See explanation above.
+    //
+    ASSERT (FwCfgDmaAddress <= MAX_UINTN - FwCfgDmaSize + 1);
+
+    DEBUG ((EFI_D_INFO, "Found FwCfg DMA @ 0x%Lx\n", FwCfgDmaAddress));
+  } else {
+    FwCfgDmaAddress = 0;
+  }
 
   if (InternalQemuFwCfgIsAvailable ()) {
     UINT32 Signature;
@@ -128,13 +194,13 @@ QemuFwCfgInitialize (
       // For DMA support, we require the DTB to advertise the register, and the
       // feature bitmap (which we read without DMA) to confirm the feature.
       //
-      if (PcdGet64 (PcdFwCfgDmaAddress) != 0) {
+      if (FwCfgDmaAddress != 0) {
         UINT32 Features;
 
         QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
         Features = QemuFwCfgRead32 ();
         if ((Features & BIT1) != 0) {
-          mFwCfgDmaAddress = PcdGet64 (PcdFwCfgDmaAddress);
+          mFwCfgDmaAddress = FwCfgDmaAddress;
           InternalQemuFwCfgReadBytes = DmaReadBytes;
         }
       }
diff --git a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
index 298aa6edfb..eff4a21650 100644
--- a/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
+++ b/ArmVirtPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
@@ -46,9 +46,10 @@
   BaseMemoryLib
   DebugLib
   IoLib
-  PcdLib
+  UefiBootServicesTableLib
 
-[Pcd]
-  gArmVirtTokenSpaceGuid.PcdFwCfgSelectorAddress
-  gArmVirtTokenSpaceGuid.PcdFwCfgDataAddress
-  gArmVirtTokenSpaceGuid.PcdFwCfgDmaAddress
+[Protocols]
+  gFdtClientProtocolGuid                                ## CONSUMES
+
+[Depex]
+  gFdtClientProtocolGuid
-- 
2.39.2