audk/BeagleBoardPkg/Sec/Arm/ModuleEntryPoint.asm

//------------------------------------------------------------------------------ 
//
// Copyright (c) 2008-2009 Apple Inc. All rights reserved.
//
// 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 <AsmMacroIoLib.h>
#include <Library/PcdLib.h>
#include <AutoGen.h>
  INCLUDE AsmMacroIoLib.inc
  
  IMPORT  CEntryPoint
  EXPORT  _ModuleEntryPoint
        
  PRESERVE8
  AREA    ModuleEntryPoint, CODE, READONLY
  

_ModuleEntryPoint
 
  //Disable L2 cache
  mrc     p15, 0, r0, c1, c0, 1   // read Auxiliary Control Register
  bic     r0, r0, #0x00000002     // disable L2 cache
  mcr     p15, 0, r0, c1, c0, 1   // store Auxiliary Control Register
  
  //Enable Strict alignment checking & Instruction cache
  mrc     p15, 0, r0, c1, c0, 0
  bic     r0, r0, #0x00002300     /* clear bits 13, 9:8 (--V- --RS) */
  bic     r0, r0, #0x00000005     /* clear bits 0, 2 (---- -C-M) */
  orr     r0, r0, #0x00000002     /* set bit 1 (A) Align */
  orr     r0, r0, #0x00001000     /* set bit 12 (I) enable I-Cache */
  mcr     p15, 0, r0, c1, c0, 0
 
  // Set CPU vectors to start of DRAM
  LoadConstantToReg (FixedPcdGet32(PcdCpuVectorBaseAddress) ,r0) // Get vector base
  mcr     p15, 0, r0, c12, c0, 0
  isb                               // Sync changes to control registers

  // Fill vector table with branchs to current pc (jmp $)
  ldr     r1, ShouldNeverGetHere
  movs    r2, #0
FillVectors
  str     r1, [r0, r2]
  adds    r2, r2, #4
  cmp     r2, #32
  bne     FillVectors
   
  /* before we call C code, lets setup the stack pointer in internal RAM */
stack_pointer_setup

  //
  // Set stack based on PCD values. Need to do it this way to make C code work 
  // when it runs from FLASH. 
  //  
  LoadConstantToReg (FixedPcdGet32(PcdPrePiStackBase) ,r2)    // stack base arg2  
  LoadConstantToReg (FixedPcdGet32(PcdPrePiStackSize) ,r3)    // stack size arg3  
  add     r4, r2, r3

  //Enter SVC mode and set up SVC stack pointer
  mov     r5,#0x13|0x80|0x40
  msr     CPSR_c,r5
  mov     r13,r4

  // Call C entry point
  LoadConstantToReg (FixedPcdGet32(PcdMemorySize) ,r1)    // memory size arg1         
  LoadConstantToReg (FixedPcdGet32(PcdMemoryBase) ,r0)    // memory start arg0
  blx     CEntryPoint                                     // Assume C code is thumb    

ShouldNeverGetHere
  /* _CEntryPoint should never return */
  b       ShouldNeverGetHere
  
  END