[PATCH v2 04/14] ArmVirtPkg/PrePi: move DRAM discovery code into PrePi

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

ArmVirtQemuKernel and ArmVirtXen use essentially the same code to
retrieve DRAM information from the DT /memory node at early boot,
and invoke it via the ArmPlatformPeiBootAction () hook exposed by
ArmPlatformLib. Let's move this code into the PrePi implementation
these platforms share between them (and not with any other platforms)
so we can eliminate another dependency on the messy ArmPlatformLib.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>
---
 ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S         | 77 ++++++++++++++++-
 ArmVirtPkg/PrePi/Arm/ModuleEntryPoint.S             | 71 +++++++++++++++
 ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf |  2 +
 ArmVirtPkg/PrePi/FdtParser.c                        | 90 ++++++++++++++++++++
 4 files changed, 238 insertions(+), 2 deletions(-)

diff --git a/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S b/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S
index 7a9c0c3787cc..3296aedfe9aa 100644
--- a/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S
+++ b/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S
@@ -49,8 +49,7 @@ ASM_FUNC(_ModuleEntryPoint)
   b     .Lreloc_loop
 .Lreloc_done:
 
-  // Do early platform specific actions
-  bl    ASM_PFX(ArmPlatformPeiBootAction)
+  bl    ASM_PFX(DiscoverDramFromDt)
 
   // Get ID of this CPU in Multicore system
   bl    ASM_PFX(ArmReadMpidr)
@@ -140,3 +139,77 @@ _GetStackBase:
 
 _NeverReturn:
   b _NeverReturn
+
+// VOID
+// DiscoverDramFromDt (
+//   VOID   *DeviceTreeBaseAddress,   // passed by loader in x0
+//   VOID   *ImageBase                // passed by FDF trampoline in x1
+//   );
+ASM_PFX(DiscoverDramFromDt):
+  //
+  // If we are booting from RAM using the Linux kernel boot protocol, x0 will
+  // point to the DTB image in memory. Otherwise, use the default value defined
+  // by the platform.
+  //
+  cbnz  x0, 0f
+  ldr   x0, PcdGet64 (PcdDeviceTreeInitialBaseAddress)
+
+0:mov   x29, x30            // preserve LR
+  mov   x28, x0             // preserve DTB pointer
+  mov   x27, x1             // preserve base of image pointer
+
+  //
+  // The base of the runtime image has been preserved in x1. Check whether
+  // the expected magic number can be found in the header.
+  //
+  ldr   w8, .LArm64LinuxMagic
+  ldr   w9, [x1, #0x38]
+  cmp   w8, w9
+  bne   .Lout
+
+  //
+  //
+  // OK, so far so good. We have confirmed that we likely have a DTB and are
+  // booting via the arm64 Linux boot protocol. Update the base-of-image PCD
+  // to the actual relocated value, and add the shift of PcdFdBaseAddress to
+  // PcdFvBaseAddress as well
+  //
+  adr   x8, PcdGet64 (PcdFdBaseAddress)
+  adr   x9, PcdGet64 (PcdFvBaseAddress)
+  ldr   x6, [x8]
+  ldr   x7, [x9]
+  sub   x7, x7, x6
+  add   x7, x7, x1
+  str   x1, [x8]
+  str   x7, [x9]
+
+  //
+  // Discover the memory size and offset from the DTB, and record in the
+  // respective PCDs. This will also return false if a corrupt DTB is
+  // encountered. Since we are calling a C function, use the window at the
+  // beginning of the FD image as a temp stack.
+  //
+  adr   x1, PcdGet64 (PcdSystemMemoryBase)
+  adr   x2, PcdGet64 (PcdSystemMemorySize)
+  mov   sp, x7
+  bl    FindMemnode
+  cbz   x0, .Lout
+
+  //
+  // Copy the DTB to the slack space right after the 64 byte arm64/Linux style
+  // image header at the base of this image (defined in the FDF), and record the
+  // pointer in PcdDeviceTreeInitialBaseAddress.
+  //
+  adr   x8, PcdGet64 (PcdDeviceTreeInitialBaseAddress)
+  add   x27, x27, #0x40
+  str   x27, [x8]
+
+  mov   x0, x27
+  mov   x1, x28
+  bl    CopyFdt
+
+.Lout:
+  ret    x29
+
+.LArm64LinuxMagic:
+  .byte   0x41, 0x52, 0x4d, 0x64
diff --git a/ArmVirtPkg/PrePi/Arm/ModuleEntryPoint.S b/ArmVirtPkg/PrePi/Arm/ModuleEntryPoint.S
index eebf660acdb2..a918c191432e 100644
--- a/ArmVirtPkg/PrePi/Arm/ModuleEntryPoint.S
+++ b/ArmVirtPkg/PrePi/Arm/ModuleEntryPoint.S
@@ -148,3 +148,74 @@ _GetStackBase:
 
 _NeverReturn:
   b _NeverReturn
+
+ASM_PFX(ArmPlatformPeiBootAction):
+  //
+  // If we are booting from RAM using the Linux kernel boot protocol, r0 will
+  // point to the DTB image in memory. Otherwise, use the default value defined
+  // by the platform.
+  //
+  teq   r0, #0
+  bne   0f
+  LDRL  (r0, PcdGet64 (PcdDeviceTreeInitialBaseAddress))
+
+0:mov   r11, r14            // preserve LR
+  mov   r10, r0             // preserve DTB pointer
+  mov   r9, r1              // preserve base of image pointer
+
+  //
+  // The base of the runtime image has been preserved in r1. Check whether
+  // the expected magic number can be found in the header.
+  //
+  ldr   r8, .LArm32LinuxMagic
+  ldr   r7, [r1, #0x24]
+  cmp   r7, r8
+  bne   .Lout
+
+  //
+  //
+  // OK, so far so good. We have confirmed that we likely have a DTB and are
+  // booting via the ARM Linux boot protocol. Update the base-of-image PCD
+  // to the actual relocated value, and add the shift of PcdFdBaseAddress to
+  // PcdFvBaseAddress as well
+  //
+  ADRL  (r8, PcdGet64 (PcdFdBaseAddress))
+  ADRL  (r7, PcdGet64 (PcdFvBaseAddress))
+  ldr   r6, [r8]
+  ldr   r5, [r7]
+  sub   r5, r5, r6
+  add   r5, r5, r1
+  str   r1, [r8]
+  str   r5, [r7]
+
+  //
+  // Discover the memory size and offset from the DTB, and record in the
+  // respective PCDs. This will also return false if a corrupt DTB is
+  // encountered. Since we are calling a C function, use the window at the
+  // beginning of the FD image as a temp stack.
+  //
+  ADRL  (r1, PcdGet64 (PcdSystemMemoryBase))
+  ADRL  (r2, PcdGet64 (PcdSystemMemorySize))
+  mov   sp, r5
+  bl    FindMemnode
+  teq   r0, #0
+  beq   .Lout
+
+  //
+  // Copy the DTB to the slack space right after the 64 byte arm64/Linux style
+  // image header at the base of this image (defined in the FDF), and record the
+  // pointer in PcdDeviceTreeInitialBaseAddress.
+  //
+  ADRL  (r8, PcdGet64 (PcdDeviceTreeInitialBaseAddress))
+  add   r9, r9, #0x40
+  str   r9, [r8]
+
+  mov   r0, r9
+  mov   r1, r10
+  bl    CopyFdt
+
+.Lout:
+  bx    r11
+
+.LArm32LinuxMagic:
+  .byte   0x18, 0x28, 0x6f, 0x01
diff --git a/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf b/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf
index 5e706934f69f..789a896857aa 100755
--- a/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf
+++ b/ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf
@@ -23,6 +23,7 @@ [Defines]
 
 [Sources]
   PrePi.c
+  FdtParser.c
 
 [Sources.AArch64]
   AArch64/ArchPrePi.c
@@ -44,6 +45,7 @@ [Packages]
 [LibraryClasses]
   BaseLib
   DebugLib
+  FdtLib
   ArmLib
   IoLib
   TimerLib
diff --git a/ArmVirtPkg/PrePi/FdtParser.c b/ArmVirtPkg/PrePi/FdtParser.c
new file mode 100644
index 000000000000..afdc81a8839d
--- /dev/null
+++ b/ArmVirtPkg/PrePi/FdtParser.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2015, Linaro Ltd. All rights reserved.
+ *
+ * This program and the accompanying materials
+ * are licensed and made available under the terms and conditions of the BSD License
+ * which accompanies this distribution.  The full text of the license may be found at
+ * http://opensource.org/licenses/bsd-license.php
+ *
+ * THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+ */
+
+#include <Uefi.h>
+#include <Include/libfdt.h>
+
+BOOLEAN
+FindMemnode (
+  IN  VOID    *DeviceTreeBlob,
+  OUT UINT64  *SystemMemoryBase,
+  OUT UINT64  *SystemMemorySize
+  )
+{
+  INT32         MemoryNode;
+  INT32         AddressCells;
+  INT32         SizeCells;
+  INT32         Length;
+  CONST INT32   *Prop;
+
+  if (fdt_check_header (DeviceTreeBlob) != 0) {
+    return FALSE;
+  }
+
+  //
+  // Look for a node called "memory" at the lowest level of the tree
+  //
+  MemoryNode = fdt_path_offset (DeviceTreeBlob, "/memory");
+  if (MemoryNode <= 0) {
+    return FALSE;
+  }
+
+  //
+  // Retrieve the #address-cells and #size-cells properties
+  // from the root node, or use the default if not provided.
+  //
+  AddressCells = 1;
+  SizeCells = 1;
+
+  Prop = fdt_getprop (DeviceTreeBlob, 0, "#address-cells", &Length);
+  if (Length == 4) {
+    AddressCells = fdt32_to_cpu (*Prop);
+  }
+
+  Prop = fdt_getprop (DeviceTreeBlob, 0, "#size-cells", &Length);
+  if (Length == 4) {
+    SizeCells = fdt32_to_cpu (*Prop);
+  }
+
+  //
+  // Now find the 'reg' property of the /memory node, and read the first
+  // range listed.
+  //
+  Prop = fdt_getprop (DeviceTreeBlob, MemoryNode, "reg", &Length);
+
+  if (Length < (AddressCells + SizeCells) * sizeof (INT32)) {
+    return FALSE;
+  }
+
+  *SystemMemoryBase = fdt32_to_cpu (Prop[0]);
+  if (AddressCells > 1) {
+    *SystemMemoryBase = (*SystemMemoryBase << 32) | fdt32_to_cpu (Prop[1]);
+  }
+  Prop += AddressCells;
+
+  *SystemMemorySize = fdt32_to_cpu (Prop[0]);
+  if (SizeCells > 1) {
+    *SystemMemorySize = (*SystemMemorySize << 32) | fdt32_to_cpu (Prop[1]);
+  }
+
+  return TRUE;
+}
+
+VOID
+CopyFdt (
+  IN    VOID    *FdtDest,
+  IN    VOID    *FdtSource
+  )
+{
+  fdt_pack(FdtSource);
+  CopyMem (FdtDest, FdtSource, fdt_totalsize (FdtSource));
+}
-- 
2.11.0