arm2410

arm2410和44b0启动文件分析（很全面）工程里面的头文件 2410Init.s包括了板子上电后的初始化，具体有几个步骤：讲述S3C2410启动程序设计1. 屏蔽所有中断，关看门狗。

2. 根据工作频率设置PLL寄存器3. 初始化存储控制相关寄存器4. 初始化各模式下的栈指针5. 设置缺省中断处理函数6. 将数据段拷贝到RAM中，将零初始化数据段清零7. 跳转到C语言Main入口函数中要看懂这个头文件是比较难的，我跟DVD视频的教程看了两遍，弄懂了一些，视频上讲的是 ARM7 S3C44B0的 Init.s 但我觉得和2410的差不多。

我将这个程序注释了一下。

可能有些地方不是很正确，只提供参考。

;=========================================; NAME: 2410INIT.S; DESC: C start up codes; Configure memory, ISR ,stacks; Initialize C-variables; HISTORY:; 2002.02.25:kwtark: ver 0.0; 2002.03.20: purnnamu: Add some functions for testing STOP,POWER_OFF mode; 2002.04.10:SJS:sub interrupt disable 0x3ff -> 0x7ff; 2002.11.29:Kong: DCD BANKSIZE Resiger 0x32 -> 0xb2 (ARM core burst enable);=========================================INCLUDE option.incINCLUDE memcfg.incINCLUDE 2410addr.incBIT_SELFREFRESH EQU (1<<22);下面是对arm处理器模式寄存器对应值的常数定义，arm处理器中有一个CPSR程序状态寄存器它的后五位决定目前的处理器模式; pre-defined constantsUSERMODE EQU 0x10FIQMODE EQU 0x11IRQMODE EQU 0x12SVCMODE EQU 0x13ABORTMODE EQU 0x17UNDEFMODE EQU 0x1bMODEMASK EQU 0x1fNOINT EQU 0xc0;The location of stacksUserStack EQU (_STACK_BASEADDRESS-0x3800) ;0x33ff4800 ~ SVCStack EQU (_STACK_BASEADDRESS-0x2800) ;0x33ff5800 ~ UndefStack EQU (_STACK_BASEADDRESS-0x2400) ;0x33ff5c00 ~ AbortStack EQU (_STACK_BASEADDRESS-0x2000) ;0x33ff6000 ~ IRQStack EQU (_STACK_BASEADDRESS-0x1000) ;0x33ff7000 ~ FIQStack EQU (_STACK_BASEADDRESS-0x0) ;0x33ff8000 ~;check if tasm.exe is used.;arm处理器有两种工作状态 1.arm:32位这种工作状态下执行字对准的arm指令 2.Thumb:16位这种工作状;态执行半字对准的Thumb指令;因为处理器分为16位 32位两种工作状态程序的编译器也是分16位和32两种编译方式所以下面的程序用;于根据处理器工作状态确定编译器编译方式;code16伪指令指示汇编编译器后面的指令为16位的thumb指令;code32伪指令指示汇编编译器后面的指令为32位的arm指令;这段是为了统一目前的处理器工作状态和软件编译方式（16位编译环境使用tasm.exe编译;Check if tasm.exe(armasm -16 ...@ADS 1.0) is used.GBLL THUMBCODE[ {CONFIG} = 16 ;if config==16 这里表示你的目前处于领先地16位编译方式THUMBCODE SETL {TRUE};设置THUMBCODE 为 trueCODE32;转入32位编译模式| ;elseTHUMBCODE SETL {FALSE};设置THUMBCODE 为 false]MACROMOV_PC_LR[ THUMBCODEbx lr|mov pc,lr]MENDMACROMOVEQ_PC_LR[ THUMBCODEbxeq lr|moveq pc,lr]MEND;注意下面这段程序是个宏定义很多人对这段程序不理解我再次强调这是一个宏定义所以大家要注意了;下面包含的HandlerXXX HANDLER HandleXXX将都被下面这段程序展开;这段程序用于把中断服务程序的首地址装载到pc中，有人称之为“加载程序”。

;本初始化程序定义了一个数据区（在文件最后），34个字空间，存放相应中断服务程序的首地址。

每个字;空间都有一个标号，以Handle***命名。

;在向量中断模式下使用“加载程序”来执行中断服务程序。

;这里就必须讲一下向量中断模式和非向量中断模式的概念;向量中断模式是当cpu读取位于0x18处的IRQ中断指令的时候，系统自动读取对应于该中断源确定地址上的;;指令取代0x18处的指令，通过跳转指令系统就直接跳转到对应地址;函数中节省了中断处理时间提高了中断处理速度标例如 ADC中断的向量地址为0xC0,则在0xC0处放如下;代码：ldr PC,=HandlerADC 当ADC中断产生的时候系统会;自动跳转到HandlerADC函数中;非向量中断模式处理方式是一种传统的中断处理方法，当系统产生中断的时候，系统将interrupt; pending寄存器中对应标志位置位然后跳转到位于0x18处的统一中断;函数中该函数通过读取interrupt pending寄存器中对应标志位来判断中断源并根据优先级关系再跳到;对应中断源的处理代码中MACRO$HandlerLabel HANDLER $HandleLabel;HandlerLabel为中断服务入口地址$HandlerLabelsub sp,sp,#4 ; Decrement sp(to store jump address) ;将要使用的r0寄存器入栈stmfd sp!,{r0} ; pUSH the work register to stack(lr does't push because it return to original address)ldr r0,=$HandleLabel; load the address of HandleXXX to r0ldr r0,[r0] ; load the contents(service routine start address) of HandleXXX;将对应的中断函数首地址入栈str r0,[sp,#4] ;store the contents(ISR) of HandleXXX to stack;将中断函数首地址出栈放入程序指针中系统将跳转到对应中断处理函数ldmfd sp!,{r0,pc} ; pOP the work register and pc(jump to ISR)MEND;一个arm由RO,RW,ZI三个断组成其中RO为代码段，RW是已经初始化的全局变量，ZI是未初始化的全局变量;（对于GNU工具对应的概念是TEXT ,DATA,BSS）bootloader;bootloader要将RW段复制到ram中并将ZI段清零编译器使用下列段来记录各段的起始和结束地址; |Image$$RO$$Base| ; RO段起始地址; |Image$$RO$$Limit| ; RO段结束地址加1; |Image$$RW$$Base| ; RW段起始地址; |Image$$RW$$Limit| ; RW段结束地址加1; |Image$$ZI$$Base| ; ZI段起始地址; |Image$$ZI$$Limit| ; ZI段结束地址加1;这些标号的值是通过编译器的设定来确定的如编译软件中对ro-base 和rw-base的设定，例如 ro-;base=0xc000000 rw-base=0xc5f0000IMPORT |Image$$RO$$Limit| ; End of ROM code (=start of ROM data)IMPORT |Image$$RW$$Base| ; Base of RAM to initialiseIMPORT |Image$$ZI$$Base| ; Base and limit of areaIMPORT |Image$$ZI$$Limit| ; to zero initialiseIMPORT Main ; The main entry of mon programAREA Init,CODE,READONLY;异常中断矢量表（每个表项占4个字节）下面是中断向量表一旦系统运行时有中断发生即使移植了操作;系统如linux 处理器已经把控制权交给了操作系统一旦发生中断处理器还是会跳转到从0x0开始;中断向量表中某个中断表项（依据中断类型）开始执行;具体中断向量布局请参考s3c44b0 spec 例如 adc中断向量为0x000000c0下面对应表中第49项位置向量地址0x0+4*(49-1)=0x000000c0ENTRY;板子上电和复位后程序开始从位于0x0处开始执行硬件刚刚上电复位后程序从这里开始执行跳转到标?;为ResetHandler处执行;1)The code, which converts to Big-endian, should be in little endian code.;2)The following little endian code will be compiled in Big-Endian mode.; The code byte order should be changed as the memory bus width.;3)The pseudo instruction,DCD can't be used here because the linker generates error.;总线宽度判?; DCD用于分配一段字内存单片，并用后面的伪指令初始化;分配字节由expr 个数决定ASSERT : DEF:ENDIAN_CHANGE[ ENDIAN_CHANGEASSERT : DEF:ENTRY_BUS_WIDTH[ ENTRY_BUS_WIDTH=32b ChangeBigEndian ; DCD 0xea000007][ ENTRY_BUS_WIDTH=16andeq r14,r7,r0,lsl #20 ; DCD 0x0007ea00 ][ ENTRY_BUS_WIDTH=8streq r0,[r0,-r10,ror #1] ; DCD 0x070000ea ]|b ResetHandler]b HandlerUndef ;handler for Undefined mode b HandlerSWI ;handler for SWI interrupt b HandlerPabort ;handler for PAbortb HandlerDabort ;handler for DAbortb . ;reserved 0x14b HandlerIRQ ;handler for IRQ interrupt b HandlerFIQ ;handler for FIQ interrupt;@0x20b EnterPWDN;大小端判断ChangeBigEndian;@0x24[ ENTRY_BUS_WIDTH=32DCD 0xee110f10 ;0xee110f10 => mrc p15,0,r0,c1,c0,0DCD 0xe3800080 ;0xe3800080 => orrr0,r0,#0x80; //Big-endianDCD 0xee010f10 ;0xee010f10 => mcr p15,0,r0,c1,c0,0][ ENTRY_BUS_WIDTH=16DCD 0x0f10ee11DCD 0x0080e380DCD 0x0f10ee01][ ENTRY_BUS_WIDTH=8DCD 0x100f11eeDCD 0x800080e3DCD 0x100f01ee]DCD 0xffffffff ;swinv 0xffffff is similar with NOP and run well in both endian mode.DCD 0xffffffffDCD 0xffffffffDCD 0xffffffffDCD 0xffffffffb ResetHandler;进入掉电模式功能; 1. SDRAM 必须在自刷新模式.; 2. 所有中断必须屏蔽 for SDRAM/DRAM self-refresh.; 3. LCD 关闭for SDRAM/DRAM self-refresh.; 4. The I-cache 可能需要开启.; 5. The location of the following code may have not to be changed.;void EnterPWDN(int CLKCON);EnterPWDNmov r2,r0 ;r2=rCLKCONtst r0,#0x8 ; pOWER_OFF mode?bne ENTER_POWER_OFFENTER_STOPldr r0,=REFRESHldr r3,[r0] ;r3=rREFRESHmov r1, r3orr r1, r1, #BIT_SELFREFRESHstr r1, [r0] ;Enable SDRAM self-refreshmov r1,#16 ;wait until self-refresh is issued. may not be needed.0 subs r1,r1,#1bne %B0ldr r0,=CLKCON ;enter STOP mode.str r2,[r0]mov r1,#320 subs r1,r1,#1 ;1) wait until the STOP mode is in effect. bne %B0 ;2) Or wait here until the CPU&Peripherals will be turned-off; Entering POWER_OFF mode, only the reset by wake-up is available.ldr r0,=REFRESH ;exit from SDRAM self refresh mode.str r3,[r0]MOV_PC_LRENTER_POWER_OFF;NOTE.;1) rGSTATUS3 should have the return address after wake-up from POWER_OFF mode.ldr r0,=REFRESHldr r1,[r0] ;r1=rREFRESHorr r1, r1, #BIT_SELFREFRESHstr r1, [r0] ;Enable SDRAM self-refreshmov r1,#16 ;Wait until self-refresh is issued,which may not be needed.0 subs r1,r1,#1bne %B0ldr r1,=MISCCRldr r0,[r1]orr r0,r0,#(7<<17) ;Make sure that SCLK0:SCLK->0,SCLK1:SCLK->0, SCKE='L' during boot-upstr r0,[r1]ldr r0,=CLKCONstr r2,[r0]b . ;CPU will die here.WAKEUP_POWER_OFF;Release SCLKn after wake-up from the POWER_OFF mode.ldr r1,=MISCCRldr r0,[r1]bic r0,r0,#(7<<17) ;SCLK0:0->SCLK, SCLK1:0->SCLK, SCKE: l->Hstr r0,[r1];Set memory control registersldr r0,=SMRDATAldr r1,=BWSCON ;BWSCON Addressadd r2, r0, #52 ;End address of SMRDATAldr r3, [r0], #4str r3, [r1], #4cmp r2, r0bne %B0mov r1,#2560 subs r1,r1,#1 ;1) wait until the SelfRefresh is released.bne %B0ldr r1,=GSTATUS3 ;GSTATUS3 has the start address just after POWER_OFF wake-upldr r0,[r1]mov pc,r0LTORG;下面是具体的中断处理函数跳转的宏，通过上面的$HandlerLabel 的宏定义展开后跳转到对应的中断处理;函数（对于向量中断）HandlerFIQ HANDLER HandleFIQHandlerIRQ HANDLER HandleIRQHandlerUndef HANDLER HandleUndefHandlerSWI HANDLER HandleSWIHandlerDabort HANDLER HandleDabortHandlerPabort HANDLER HandlePabort;下面这段程序是用来处理非向量中断，具体判断I_ISPR中各位是否置1 置1表示目前此中断等待响应（每次只能有一位置1），从最高优先级中断位开始判断，检测到等待服务;中断就将pc置为中断服务函数首地址IsrIRQsub sp,sp,#4 ;预留返回指针的存储位置stmfd sp!,{r8-r9}ldr r9,=INTOFFSETldr r9,[r9];载入I_ISRldr r8,=HandleEINT0add r8,r8,r9,lsl #2ldr r8,[r8]str r8,[sp,#8]ldmfd sp!,{r8-r9,pc};=======; ENTRY;=======;扳子上电和复位后程序开始从位于0x0执行b ResetHandler 程序从跳转到这里执行;板子上电复位后执行几个步骤这里通过标号在注释中加1，2，3....标示标号表示执行顺序;1.禁止看门狗屏蔽所有中断ResetHandlerldr r0,=WTCON ;watch dog disableldr r1,=0x0str r1,[r0]ldr r0,=INTMSKldr r1,=0xffffffff ;all interrupt disablestr r1,[r0]ldr r0,=INTSUBMSKldr r1,=0x7ff ;all sub interrupt disable,2002/04/10str r1,[r0][ {FALSE}; rGPFDAT = (rGPFDAT & ~(0xf<<4)) | ((~data & 0xf)<<4); ; Led_Displayldr r0,=GPFCONldr r1,=0x5500str r1,[r0]ldr r0,=GPFDATldr r1,=0x10str r1,[r0]];2.根据工作频率设置pll;这里介绍一下计算公式;Fpllo=(m*Fin)/(p*2^s);m=MDIV+8,p=PDIV+2,s=SDIV;Fpllo必须大于20Mhz小于66Mhz;Fpllo*2^s必须小于170Mhz;如下面的PLLCON设定中的M_DIV P_DIV S_DIV是取自option.h中;#elif (MCLK==40000000);#define PLL_M (0x48);#define PLL_P (0x3);#define PLL_S (0x2);所以m=MDIV+8=80,p=PDIV+2=5,s=SDIV=2;硬件使用晶振为10Mhz,即Fin=10Mhz;Fpllo=80*10/5*2^2=40Mhz;To reduce PLL lock time, adjust the LOCKTIME register. ldr r0,=LOCKTIMEldr r1,=0xffffffstr r1,[r0][ PLL_ON_START;Configure MPLLldr r0,=MPLLCONldrr1,=((M_MDIV<<12)+(M_PDIV<<4)+M_SDIV) ;Fin=12MHz,Fout=50MHz str r1,[r0]];Check if the boot is caused by the wake-up from POWER_OFF mode.ldr r1,=GSTATUS2ldr r0,[r1]tst r0,#0x2;In case of the wake-up from POWER_OFF mode, go to POWER_OFF_WAKEUP handler.bne WAKEUP_POWER_OFFEXPORT StartPointAfterPowerOffWakeUp StartPointAfterPowerOffWakeUp;3.置存储相关寄存器的程序;这是设置SDRAM,flash ROM 存储器连接和工作时序的程序,片选定义的程序;SMRDATA map在下面的程序中定义;SMRDATA中涉及的值请参考memcfg.s程序;具体寄存器各位含义请参考s3c44b0 spec;Set memory control registersldr r0,=SMRDATAldr r1,=BWSCON ;BWSCON Addressadd r2, r0, #52 ;End address of SMRDATAldr r3, [r0], #4str r3, [r1], #4cmp r2, r0bne %B0;Initialize stacksbl InitStacks;5.设置缺省中断处理函数; Setup IRQ handlerldr r0,=HandleIRQ ;This routine is neededldr r1,=IsrIRQ ;if there isn't 'subs pc,lr,#4' at 0x18, 0x1cstr r1,[r0];Copy and paste RW data/zero initialized dataldr r0, =|Image$$RO$$Limit| ; Get pointer to ROM data ldr r1, =|Image$$RW$$Base| ; and RAM copyldr r3, =|Image$$ZI$$Base|;6.将数据段拷贝到ram中将零初始化数据段清零跳入C语言的main 函数执行到这步结束bootloader初步引导结束;Zero init base => top of initialised datacmp r0, r1 ; Check that they are differentbeq %F21cmp r1, r3 ; Copy init dataldrcc r2, [r0], #4 ;--> LDRCC r2, [r0] + ADD r0, r0, #4strcc r2, [r1], #4 ;--> STRCC r2, [r1] + ADD r1, r1, #4 bcc %B1 ;r1 < r3 继续循环2ldr r1, =|Image$$ZI$$Limit| ; Top of zero init segmentmov r2, #03cmp r3, r1 ; Zero initstrcc r2, [r3], #4bcc %B3[ : lNOT:THUMBCODEbl Main ; Don't use main() because ......b .][ THUMBCODE ;for start-up code for Thumb mode orr lr,pc,#1bx lrCODE16bl Main ; Don't use main() because ......b .CODE32];function initializing stacksInitStacks; Don't use DRAM,such as stmfd,ldmfd......;SVCstack is initialized before;Under toolkit ver 2.5, 'msr cpsr,r1' can be used instead of 'msr cpsr_cxsf,r1'mrs r0,cpsrbic r0,r0,#MODEMASK ;位清零指令,清r0,再附给roorr r1,r0,#UNDEFMODE|NOINTmsr cpsr_cxsf,r1 ;UndefModeldr sp,=UndefStackorr r1,r0,#ABORTMODE|NOINTmsr cpsr_cxsf,r1 ;AbortModeldr sp,=AbortStackorr r1,r0,#IRQMODE|NOINTmsr cpsr_cxsf,r1 ;IRQModeldr sp,=IRQStackorr r1,r0,#FIQMODE|NOINTmsr cpsr_cxsf,r1 ;FIQModeldr sp,=FIQStackbic r0,r0,#MODEMASK|NOINTorr r1,r0,#SVCMODEmsr cpsr_cxsf,r1 ;SVCModeldr sp,=SVCStack;USER mode has not be initialized.mov pc,lr;The LR register won't be valid if the current mode is not SVC mode.;这是上面提到的对存储寄存器初始化的数据mapLTORGSMRDATA DATA; Memory configuration should be optimized for best performance ; The following parameter is not optimized. ; Memory access cycle parameter strategy; 1) The memory settings is safe parameters even at HCLK='75Mhz'. ; 2) SDRAM refresh period is for HCLK='75Mhz'.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_Ta h<<4)+(B0_Tacp<<2)+(B0_PMC)) ;GCS0DCD((B1_Tacs<<13)+(B1_Tcos<<11)+(B1_Tacc<<8)+(B1_Tcoh<<6)+(B1_Ta h<<4)+(B1_Tacp<<2)+(B1_PMC)) ;GCS1DCD((B2_Tacs<<13)+(B2_Tcos<<11)+(B2_Tacc<<8)+(B2_Tcoh<<6)+(B2_Ta h<<4)+(B2_Tacp<<2)+(B2_PMC)) ;GCS2DCD((B3_Tacs<<13)+(B3_Tcos<<11)+(B3_Tacc<<8)+(B3_Tcoh<<6)+(B3_Ta h<<4)+(B3_Tacp<<2)+(B3_PMC)) ;GCS3DCD((B4_Tacs<<13)+(B4_Tcos<<11)+(B4_Tacc<<8)+(B4_Tcoh<<6)+(B4_Ta h<<4)+(B4_Tacp<<2)+(B4_PMC)) ;GCS4DCD((B5_Tacs<<13)+(B5_Tcos<<11)+(B5_Tacc<<8)+(B5_Tcoh<<6)+(B5_Ta h<<4)+(B5_Tacp<<2)+(B5_PMC)) ;GCS5DCD ((B6_MT<<15)+(B6_Trcd<<2)+(B6_SCAN)) ;GCS6DCD ((B7_MT<<15)+(B7_Trcd<<2)+(B7_SCAN)) ;GCS7; DCD((REFEN<<23)+(TREFMD<<22)+(Trp<<20)+(Trc<<18)+(Tchr<<16)+REFC NT) ;Tchr not used bitDCD((REFEN<<23)+(TREFMD<<22)+(Trp<<20)+(Trc<<18)+REFCNT) ;设置刷新周期; DCD 0x32 ;SCLK power saving mode, ARM core burst disable, BANKSIZE 128M/128MDCD 0xb2 ;SCLK power saving mode, ARM core burst enable , BANKSIZE 128M/128M - 11/29/2002DCD 0x30 ;MRSR6 CL='3clk'DCD 0x30 ;MRSR7; DCD 0x20 ;MRSR6 CL='2clk'; DCD 0x20 ;MRSR7ALIGNAREA RamData, DATA, READWRITE;这里将中断异常向量建立在sdram中^ _ISR_STARTADDRESSHandleUndef # 4HandleSWI # 4HandlePabort # 4HandleDabort # 4HandleReserved # 4HandleIRQ # 4HandleFIQ # 4; Don't use the label 'IntVectorTable',;The value of IntVectorTable is different with the address you think it may be.;IntVectorTableHandleEINT0 # 4HandleEINT1 # 4HandleEINT2 # 4HandleEINT3 # 4HandleEINT4_7 # 4HandleEINT8_23 # 4HandleRSV6 # 4HandleBATFLT # 4HandleTICK # 4HandleTIMER0 # 4 HandleTIMER1 # 4 HandleTIMER2 # 4 HandleTIMER3 # 4 HandleTIMER4 # 4 HandleUART2 # 4 HandleLCD # 4 HandleDMA0 # 4 HandleDMA1 # 4 HandleDMA2 # 4 HandleDMA3 # 4 HandleMMC # 4 HandleSPI0 # 4 HandleUART1 # 4 HandleRSV24 # 4 HandleUSBD # 4 HandleUSBH # 4 HandleIIC # 4 HandleUART0 # 4 HandleSPI1 # 4 HandleRTC # 4END最后发两个在网上下载的ARM S3C44B0的注释文件，是转载别人的。