ArmPlatformPkg/ArmRealViewEbPkg/Library/ArmRealViewEbLibRTSM/ArmRealViewEbHelper.S

   1 //
   2 //  Copyright (c) 2011, ARM Limited. All rights reserved.
   3 //
   4 //  This program and the accompanying materials
   5 //  are licensed and made available under the terms and conditions of the BSD License
   6 //  which accompanies this distribution.  The full text of the license may be found at
   7 //  http://opensource.org/licenses/bsd-license.php
   8 //
   9 //  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 //  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 //
  12 //
  13
  14 #include <AsmMacroIoLib.h>
  15 #include <Base.h>
  16 #include <Library/PcdLib.h>
  17 #include <ArmPlatform.h>
  18 #include <AutoGen.h>
  19
  20 #Start of Code section
  21 .text
  22 .align 3
  23
  24 GCC_ASM_EXPORT(ArmPlatformIsMemoryInitialized)
  25 GCC_ASM_EXPORT(ArmPlatformInitializeBootMemory)
  26
  27 /**
  28   Called at the early stage of the Boot phase to know if the memory has already been initialized
  29
  30   Running the code from the reset vector does not mean we start from cold boot. In some case, we
  31   can go through this code with the memory already initialized.
  32   Because this function is called at the early stage, the implementation must not use the stack.
  33   Its implementation must probably done in assembly to ensure this requirement.
  34
  35   @return   Return the condition value into the 'Z' flag
  36
  37 **/
  38 ASM_PFX(ArmPlatformIsMemoryInitialized):
  39   // Check if the memory has been already mapped, if so skipped the memory initialization
  40   LoadConstantToReg (ARM_EB_SYSCTRL, r0)
  41   ldr   r0, [r0, #0]
  42
  43   // 0x200 (BIT9): This read-only bit returns the remap status.
  44   and   r0, r0, #0x200
  45   tst   r0, #0x200
  46   bx    lr
  47
  48 /**
  49   Initialize the memory where the initial stacks will reside
  50
  51   This memory can contain the initial stacks (Secure and Secure Monitor stacks).
  52   In some platform, this region is already initialized and the implementation of this function can
  53   do nothing. This memory can also represent the Secure RAM.
  54   This function is called before the satck has been set up. Its implementation must ensure the stack
  55   pointer is not used (probably required to use assembly language)
  56
  57 **/
  58 ASM_PFX(ArmPlatformInitializeBootMemory):
  59   // The SMC does not need to be initialized for RTSM
  60   bx    lr
  61
  62 ASM_FUNCTION_REMOVE_IF_UNREFERENCED