mini2440启动代码分析之第十篇

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我是靠谱客的博主想人陪灯泡，最近开发中收集的这篇文章主要介绍mini2440启动代码分析之第十篇，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

;堆栈初始化的顺序决定系统最后运行在哪种处理器模式，最后初始化哪种模式的堆栈，系统就运行在哪种模式。

InitStacks
mrs r0,cpsr
bic r0,r0,#MODEMASK         ;屏蔽低5位
orr r1,r0,#UNDEFMODE|NOINT ;屏蔽6、7位和选择未定义模式
msr cpsr_cxsf,r1            ;UndefMode
ldr sp,=UndefStack          ;UndefStack=0x33FF_5C00

orr r1,r0,#ABORTMODE|NOINT
msr cpsr_cxsf,r1 ;AbortMode
ldr sp,=AbortStack ; AbortStack=0x33FF_6000

orr r1,r0,#IRQMODE|NOINT
msr cpsr_cxsf,r1 ;IRQMode
ldr sp,=IRQStack ;IRQStack=0x33FF_7000

orr r1,r0,#FIQMODE|NOINT
msr cpsr_cxsf,r1 ;FIQMode
ldr sp,=FIQStack ;FIQStack=0x33FF_8000

bic r0,r0,#MODEMASK|NOINT
orr r1,r0,#SVCMODE
msr cpsr_cxsf,r1 ;SVCMode,管理模式
ldr sp,=SVCStack ;SVCStack=0x33FF_5800

mov pc,lr

[ {TRUE}
|
ReadNandID
mov      r7,#NFCONF
ldr      r0,[r7,#4]  ;NFChipEn();
bic      r0,r0,#2
str      r0,[r7,#4]
mov      r0,#0x90  ;WrNFCmd(RdIDCMD);
strb     r0,[r7,#8]
mov      r4,#0   ;WrNFAddr(0);
strb     r4,[r7,#0xc]
1       ;while(NFIsBusy());
ldr      r0,[r7,#0x20]
tst      r0,#1
beq      %B1
ldrb     r0,[r7,#0x10] ;id = RdNFDat()<<8;
mov      r0,r0,lsl #8
ldrb     r1,[r7,#0x10] ;id |= RdNFDat();
orr      r5,r1,r0
ldr      r0,[r7,#4]  ;NFChipDs();
orr      r0,r0,#2
str      r0,[r7,#4]
mov   pc,lr

ReadNandStatus
mov   r7,#NFCONF
ldr      r0,[r7,#4]  ;NFChipEn();
bic      r0,r0,#2
str      r0,[r7,#4]
mov      r0,#0x70  ;WrNFCmd(QUERYCMD);
strb     r0,[r7,#8]
ldrb     r1,[r7,#0x10] ;r1 = RdNFDat();
ldr      r0,[r7,#4]  ;NFChipDs();
orr      r0,r0,#2
str      r0,[r7,#4]
mov   pc,lr

WaitNandBusy
mov      r0,#0x70  ;WrNFCmd(QUERYCMD);
mov      r1,#NFCONF
strb     r0,[r1,#8]
1       ;while(!(RdNFDat()&0x40));
ldrb     r0,[r1,#0x10]
tst      r0,#0x40
beq   %B1
mov      r0,#0   ;WrNFCmd(READCMD0);
strb     r0,[r1,#8]
mov      pc,lr

;============================================================================

CheckBadBlk
mov  r7, lr
mov  r5, #NFCONF

bic      r0,r0,#0x1f ;addr &= ~0x1f;
ldr      r1,[r5,#4]  ;NFChipEn()
bic      r1,r1,#2
str      r1,[r5,#4]

mov      r1,#0x50  ;WrNFCmd(READCMD2)
strb     r1,[r5,#8]
mov      r1, #5;6  ;6->5
strb     r1,[r5,#0xc] ;WrNFAddr(5);(6) 6->5
strb     r0,[r5,#0xc] ;WrNFAddr(addr)
mov      r1,r0,lsr #8 ;WrNFAddr(addr>>8)
strb     r1,[r5,#0xc]
cmp      r6,#0   ;if(NandAddr)
movne    r0,r0,lsr #16 ;WrNFAddr(addr>>16)
strneb   r0,[r5,#0xc]

; bl  WaitNandBusy ;WaitNFBusy()
;do not use WaitNandBusy, after WaitNandBusy will read part A!
mov r0, #100
1
subs r0, r0, #1
bne %B1
2
ldr r0, [r5, #0x20]
tst r0, #1
beq %B2

ldrb r0, [r5,#0x10] ;RdNFDat()
sub  r0, r0, #0xff

mov      r1,#0   ;WrNFCmd(READCMD0)
strb     r1,[r5,#8]

ldr      r1,[r5,#4]  ;NFChipDs()
orr      r1,r1,#2
str      r1,[r5,#4]

mov  pc, r7

ReadNandPage
mov   r7,lr
mov      r4,r1
mov      r5,#NFCONF

ldr      r1,[r5,#4]  ;NFChipEn()
bic      r1,r1,#2
str      r1,[r5,#4]

mov      r1,#0   ;WrNFCmd(READCMD0)
strb     r1,[r5,#8]
strb     r1,[r5,#0xc] ;WrNFAddr(0)
strb     r0,[r5,#0xc] ;WrNFAddr(addr)
mov      r1,r0,lsr #8 ;WrNFAddr(addr>>8)
strb     r1,[r5,#0xc]
cmp      r6,#0   ;if(NandAddr)
movne    r0,r0,lsr #16 ;WrNFAddr(addr>>16)
strneb   r0,[r5,#0xc]

ldr      r0,[r5,#4]  ;InitEcc()
orr      r0,r0,#0x10
str      r0,[r5,#4]

bl       WaitNandBusy ;WaitNFBusy()

mov      r0,#0   ;for(i=0; i<512; i++)
1
ldrb     r1,[r5,#0x10] ;buf[i] = RdNFDat()
strb     r1,[r4,r0]
add      r0,r0,#1
bic      r0,r0,#0x10000
cmp      r0,#0x200
bcc      %B1

ldr      r0,[r5,#4]  ;NFChipDs()
orr      r0,r0,#2
str      r0,[r5,#4]

mov   pc,r7
]

;===================================================================================

LTORG

;GCS0->SST39VF1601
;GCS1->16c550
;GCS2->IDE
;GCS3->CS8900
;GCS4->DM9000
;GCS5->CF Card
;GCS6->SDRAM
;GCS7->unused

SMRDATA DATA ;SMRDATA是段名，DATA是属性（定义为数据段）

;DCD指令用于分配一片连续的字存储单元并用伪指令中指定的表达式初始化
DCD (0+(B1_BWSCON<<4)+(B2_BWSCON<<8)+(B3_BWSCON<<12)+(B4_BWSCON<<16)+(B5_BWSCON<<20)+(B6_BWSCON<<24)+(B7_BWSCON<<28))
DCD ((B0_Tacs<<13)+(B0_Tcos<<11)+(B0_Tacc<<8)+(B0_Tcoh<<6)+(B0_Tah<<4)+(B0_Tacp<<2)+(B0_PMC))   ;GCS0
DCD ((B1_Tacs<<13)+(B1_Tcos<<11)+(B1_Tacc<<8)+(B1_Tcoh<<6)+(B1_Tah<<4)+(B1_Tacp<<2)+(B1_PMC))   ;GCS1
DCD ((B2_Tacs<<13)+(B2_Tcos<<11)+(B2_Tacc<<8)+(B2_Tcoh<<6)+(B2_Tah<<4)+(B2_Tacp<<2)+(B2_PMC))   ;GCS2
DCD ((B3_Tacs<<13)+(B3_Tcos<<11)+(B3_Tacc<<8)+(B3_Tcoh<<6)+(B3_Tah<<4)+(B3_Tacp<<2)+(B3_PMC))   ;GCS3
DCD ((B4_Tacs<<13)+(B4_Tcos<<11)+(B4_Tacc<<8)+(B4_Tcoh<<6)+(B4_Tah<<4)+(B4_Tacp<<2)+(B4_PMC))   ;GCS4
DCD ((B5_Tacs<<13)+(B5_Tcos<<11)+(B5_Tacc<<8)+(B5_Tcoh<<6)+(B5_Tah<<4)+(B5_Tacp<<2)+(B5_PMC))   ;GCS5
DCD ((B6_MT<<15)+(B6_Trcd<<2)+(B6_SCAN))    ;GCS6
DCD ((B7_MT<<15)+(B7_Trcd<<2)+(B7_SCAN))    ;GCS7
DCD ((REFEN<<23)+(TREFMD<<22)+(Trp<<20)+(Tsrc<<18)+(Tchr<<16)+REFCNT)