mx21_pagetable.c

来自「MX21_InitCodeLib.rar freescale mx21系列AR」· C语言 代码 · 共 72 行

/**********************************************************************
*
*         (C) COPYRIGHT 2004 FREESCALE, INC.
*         ALL RIGHTS RESERVED
*
*
*     Group/Division: WMSG/MMDO
*
*     Description:
*
*     Related Specifications:
*
*     Errata:
*
*     File Name: MX21_PageTable.c
*     Revision Number: 0.1
*     Author(s): Sharad Kumar
*     Date created:
*     Revision History:
*        Date      Rev     Description
*        ----      ---     -----------
*        30Apr2004  0.1     First Draft
*
**********************************************************************/
#include <stdio.h>
#include "MX21_DataTypes.h"
#include "MX21_PageTable.h"


//---------------------------------------------------
// setup the pagetable. All first level descriptors are sections.
// The default vector table address is remapped to an SDRAM
// location, as there is ROM at 0x0.  
//---------------------------------------------------

unsigned long const*
ARM_MMUTableSetUp(void)
{

  // local variables	
  uint32_t i;
  unsigned long *p = &pagetable[0];
  
  // remap default vector table jump address 
  // to an SDRAM location (0xC0000000)
  // with attributes of non cacheable and non bufferable
  *(p++) = (MMU_SDRAM_BASE_ADDR  | MMU_TYPE_SECTION | MMU_PERMISSIONS | MMU_SET_BIT4 |
            MMU_CACHEABLE | MMU_BUFFERABLE);

  // set up contiguous sections in the
  // page tables.
    for(i=1; i < MMU_PAGE_ENTRIES; i++)
  {

     // Registers, EIM, PCMCIA, NAND Flash are
     // non cacheable, non bufferable     
     if((MMU_REG_OFFST == i) || (MMU_EIM_OFFST == i)) {
     
       // left shift by 20 provides a
       // 1 MB offset.
       *(p++) =  ((i << 20) | MMU_TYPE_SECTION | MMU_PERMISSIONS | MMU_SET_BIT4);  
     }
     else {
       *(p++) =  ((i << 20) | MMU_TYPE_SECTION | MMU_PERMISSIONS | 
                              MMU_SET_BIT4 | MMU_CACHEABLE | MMU_BUFFERABLE) | MMU_SET_BIT4;
     }
          
  }
  // return the base address 
  // of the pagetables
   return pagetable;
}