/************************************************
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;
//========================== 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();
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();
#if 0
//To complete MMU_Init() fast, Icache may be turned on here.
MMU_EnableICache();
#endif
MMU_DisableMMU();
MMU_InvalidateTLB();
//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
//下面3条代码是对s3c2440虚拟地址映射到物理地址（内存）的操作，2440是bank6的。
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);
MMU_SetDomain(0x55555550|DOMAIN1_ATTR|DOMAIN0_ATTR);
//DOMAIN1: no_access, DOMAIN0,2~15=client(AP is checked)
MMU_SetProcessId(0x0);
MMU_EnableAlignFault();
MMU_EnableMMU();
MMU_EnableICache();
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;
volatile int i,nSec;
pTT=(U32 *)_MMUTT_STARTADDRESS+(vaddrStart>>20);
nSec=(vaddrEnd>>20)-(vaddrStart>>20);
for(i=0;i<=nSec;i++)
*pTT++=attr |(((paddrStart>>20)+i)<<20);
}
//上面这个函数是分析的重点。vaddrstart是虚拟地址的起始地址，vaddrend是虚拟地址的结束地址，paddrstart是物理地址的开始地址，也就是把内存上从paddrstart开始到距离paddrstart （（vaddrend>>20）-（varrdstart>>20））的这部分内存空间映射到虚拟地址上。
以MMU_SetMTT(0x30000000,0x30100000,0x30000000,RW_CB); //bank6-1 为例：
虚拟起始地址是0x30000000，结束地址是0x30100000，物理地址是0x3000000，RW_CB是对内存的访问权限控制。从0x30000000（起始地址）到0x300FFFFF的内存是1M，从0x30100000（结束地址）到0x301FFFFF又是1M，因此函数将0x30000000到0x30100000的虚拟地址映射到物理地址0x30000000开始的2M空间。参考下图：
函数中_MMUTT_STARTADDRESS的值是0x33ff8000这是我们从2^32的虚拟地址中取出做为映射物理地址的地址。
pTT=(U32 *)_MMUTT_STARTADDRESS+(vaddrStart>>20);得到的pTT为0x33ff8300，就是说2M的物理地址将从这里开始得到映射 。
nSec=(vaddrEnd>>20)-(vaddrStart>>20);得到的是对Translation Table中段（section）的索引（index），其中每段为1M。这里我们得到的nSec是1。
for(i=0;i<=nSec;i++) //i取到0和1，也就是两个段（2M）