mmu的初始化程序,我查了很久都没有找到一个系统的学资料,现发出初始化原代码,希望,各位高手能分析一下程序中各函数的作用,初始化流程.这也会为以后的初学者有很大帮助的,谢谢!
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#include "../inc/def.h"
#include "../inc/config.h"
#include "../inc/board.h"
#include "../inc/utils.h"
#include "../inc/slib.h"
#include "../inc/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.
void MMU_DCacheCleanAll(void)
{
int i, j;
//If write-back is used,the DCache should be cleared.
for(i=0; i<64; i++)
for(j=0; j<8; j++)
MMU_CleanDCacheIndex((i<<26)|(j<<5));
__asm {
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 // drain WB
}
}
void MMU_DCacheCleanInvalidateAll(void)
{
int i, j;
//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));
__asm {
mov r0, #0
mcr p15, 0, r0, c7, c10, 4 // drain WB
}
}
void MMU_Init(MMU_Table table[])
{
//========================== 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();
MMU_InvalidateDCache(); //invalidate data cache all
MMU_DCacheCleanInvalidateAll();
MMU_InvalidateICache();
#if 0
//To complete MMU_Init() fast, Icache may be turned on here.
MMU_EnableICache();
#endif
MMU_DisableMMU();
MMU_InvalidateTLB();
for(; table->vEnd; table++)
MMU_SetMTT(table->vStart, table->vEnd, table->pStart, table->attr);
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(U32 vaddrStart, U32 vaddrEnd, U32 paddrStart, int attr)
{
U32 *pTT;
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);
}
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