S3C2440裸机驱动--MMU源码分析

转自：http://blog.csdn.net/liufei_learning/article/details/6887407

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/************************************************

NAME : MMU.C

DESC :

Revision : 1.0

************************************************/



#include "def.h"

#include "option.h"

#include "2440addr.h"

#include "2440lib.h"

#include "2440slib.h"

#include "mmu.h"



// 1) Only the section table is used.

// 2) The cachable/non-cachable area can be changed by MMT_DEFAULT value.

// The section size is 1MB.





extern char __ENTRY[];



void MMU_Init(void)

{

int i,j;

/*

这段程序不能实现当前堆栈和代码区域的重新映射，假如你

想让存储区域自由映射，需要你自己编写一个细致入微的MMU初始化代码

*/

//========================== IMPORTANT NOTE =========================

//The current stack and code area can't be re-mapped in this routine.

//If you want memory map mapped freely, your own sophiscated MMU

//initialization code is needed.

//===================================================================



MMU_DisableDCache();//禁止数据高速缓存

MMU_DisableICache();//禁止指令高速缓存



//要使用回写操作，一定要对DCache进行清除

//If write-back is used,the DCache should be cleared.

for(i=0;i<64;i++)

for(j=0;j<8;j++)

MMU_CleanInvalidateDCacheIndex((i<<26)|(j<<5));//使整个DCache的数据无效

MMU_InvalidateICache();//使无效整个指令Cache



#if 0

//To complete MMU_Init() fast, Icache may be turned on here.

//为了快速完成MMU_Init(), Icache在这打开。

MMU_EnableICache();

#endif



MMU_DisableMMU();//禁止MMU

MMU_InvalidateTLB();//使快表无效



//MMU_SetMTT(int vaddrStart,int vaddrEnd,int paddrStart,int attr)

//MMU_SetMTT(0x00000000,0x07f00000,0x00000000,RW_CNB); //bank0

MMU_SetMTT(0x00000000,0x03f00000,(int)__ENTRY,RW_CB); //bank0

MMU_SetMTT(0x04000000,0x07f00000,0,RW_NCNB); //bank0

MMU_SetMTT(0x08000000,0x0ff00000,0x08000000,RW_CNB); //bank1

MMU_SetMTT(0x10000000,0x17f00000,0x10000000,RW_NCNB); //bank2

MMU_SetMTT(0x18000000,0x1ff00000,0x18000000,RW_NCNB); //bank3

//MMU_SetMTT(0x20000000,0x27f00000,0x20000000,RW_CB); //bank4

MMU_SetMTT(0x20000000,0x27f00000,0x20000000,RW_CNB); //bank4 for STRATA Flash

MMU_SetMTT(0x28000000,0x2ff00000,0x28000000,RW_NCNB); //bank5

//30f00000->30100000, 31000000->30200000

MMU_SetMTT(0x30000000,0x30100000,0x30000000,RW_CB); //bank6-1

MMU_SetMTT(0x30200000,0x33e00000,0x30200000,RW_NCNB); //bank6-2

//

MMU_SetMTT(0x33f00000,0x33f00000,0x33f00000,RW_CB); //bank6-3

MMU_SetMTT(0x38000000,0x3ff00000,0x38000000,RW_NCNB); //bank7



MMU_SetMTT(0x40000000,0x47f00000,0x40000000,RW_NCNB); //SFR

MMU_SetMTT(0x48000000,0x5af00000,0x48000000,RW_NCNB); //SFR

MMU_SetMTT(0x5b000000,0x5b000000,0x5b000000,RW_NCNB); //SFR

MMU_SetMTT(0x5b100000,0xfff00000,0x5b100000,RW_FAULT);//not used





MMU_SetTTBase(_MMUTT_STARTADDRESS);//写转换表基地址到C2

MMU_SetDomain(0x55555550|DOMAIN1_ATTR|DOMAIN0_ATTR);

//DOMAIN1: no_access, DOMAIN0,2~15=client(AP is checked)

//写域访问控制位到C3

MMU_SetProcessId(0x0); //快速上下文切换,禁止? MVA="VA"

MMU_EnableAlignFault();//是否开启地址对齐检查功能



MMU_EnableMMU();//使能MMU

MMU_EnableICache();// 使能ICache



//DCache 必须要打开，当MMU打开时.

MMU_EnableDCache(); //DCache should be turned on after MMU is turned on.

}





// attr=RW_CB,RW_CNB,RW_NCNB,RW_FAULT

void ChangeRomCacheStatus(int attr)

{

int i,j;

MMU_DisableDCache();

MMU_DisableICache();

//If write-back is used,the DCache should be cleared.

for(i=0;i<64;i++)

for(j=0;j<8;j++)

MMU_CleanInvalidateDCacheIndex((i<<26)|(j<<5));

MMU_InvalidateICache();

MMU_DisableMMU();

MMU_InvalidateTLB();

MMU_SetMTT(0x00000000,0x07f00000,0x00000000,attr); //bank0

MMU_SetMTT(0x08000000,0x0ff00000,0x08000000,attr); //bank1

MMU_EnableMMU();

MMU_EnableICache();

MMU_EnableDCache();

}





void MMU_SetMTT(int vaddrStart,int vaddrEnd,int paddrStart,int attr)

{

volatile U32 *pTT;//定义了页表的指针

volatile int i,nSec;

pTT=(U32 *)_MMUTT_STARTADDRESS+(vaddrStart>>20);//由于内存块是1M的，写页表的基地址

nSec=(vaddrEnd>>20)-(vaddrStart>>20);// nSec:段大小



//页表存储访问信息和存储块的基地址

//(((paddrStart>>20)+i)<<20) ：对应的物理内存页的地址

// attr：访问权限和缓冲属性

for(i=0;i<=nSec;i++)*pTT++=attr |(((paddrStart>>20)+i)<<20);

}



/************************************************

NAME : MMU.H

DESC :

Revision: 1.0

************************************************/



#include "2440slib.h"



#ifndef __MMU_H__

#define __MMU_H__

#ifdef __cplusplus

extern "C" {

#endif



#define DESC_SEC (0x2|(1<<4))

#define CB (3<<2) //cache_on, write_back

#define CNB (2<<2) //cache_on, write_through

#define NCB (1<<2) //cache_off,WR_BUF on

#define NCNB (0<<2) //cache_off,WR_BUF off

#define AP_RW (3<<10) //supervisor=RW, user=RW

#define AP_RO (2<<10) //supervisor=RW, user=RO



#define DOMAIN_FAULT (0x0)

#define DOMAIN_CHK (0x1)

#define DOMAIN_NOTCHK (0x3)

#define DOMAIN0 (0x0<<5)

#define DOMAIN1 (0x1<<5)



#define DOMAIN0_ATTR (DOMAIN_CHK<<0)

#define DOMAIN1_ATTR (DOMAIN_FAULT<<2)



#define RW_CB (AP_RW|DOMAIN0|CB|DESC_SEC)

#define RW_CNB (AP_RW|DOMAIN0|CNB|DESC_SEC)

#define RW_NCNB (AP_RW|DOMAIN0|NCNB|DESC_SEC)

#define RW_FAULT (AP_RW|DOMAIN1|NCNB|DESC_SEC)



void MMU_Init(void);

void MMU_SetMTT(int vaddrStart,int vaddrEnd,int paddrStart,int attr);

void ChangeRomCacheStatus(int attr);



#ifdef __cplusplus

}

#endif



#endif /*__MMU_H__*/



//具体.h参数请翻看数据手册，及《ARM体系结构与编程+杜春雷》一书