startup.s

基于dragon_MX1_ads的装载启动代码armboot

#ifdef SyncFlash
	.equ	SOURCE,	0x0C000100
#endif
#ifdef AMDFlash
	.equ	SOURCE, 0x10000100
#endif
	.equ	TARGET,	0x0AFE0100
	.equ    SDCTL0,  0x221000 
	.equ    SDCTL1,  0x221004 
// size is stored in location 0x0C0000FC
	
	.global	_start
_start:

//;*************************************** 
//;*  Init SDRAM and Flash               * 
//;*************************************** 

  //      ;*************** 
  //      ;* SDRAM 
  //      ;*************** 
  
	 LDR  r1, =SDCTL0 

       // ; Set Precharge Command 
        LDR  r3, =0x92120200
        //ldr r3,=0x92120251 
        STR  r3, [r1] 
  
       // ; Issue Precharge All Commad 
        LDR  r3, =0x8200000 
        LDR  r2, [r3] 
  
       // ; Set AutoRefresh Command 
        LDR  r3, =0xA2120200 
        STR  r3, [r1] 

       // ; Issue AutoRefresh Command 
        LDR  r3, =0x8000000 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
        LDR  r2, [r3] 
  
      //  ; Set Mode Register 
        LDR  r3, =0xB2120200 
        STR  r3, [r1] 

      //  ; Issue Mode Register Command 
        LDR  r3, =0x08111800 //; Mode Register Value 
        LDR  r2, [r3] 

      //  ; Set Normal Mode 
      //  LDR  r3, =0x82124200 
      	LDR  r3, =0x8212C267;
        STR  r3, [r1] 

//;*************************************** 
//;*  End of SDRAM and Flash Init        * 
//;*************************************** 


// copy code from FLASH to SRAM

_CopyCodes:
	ldr	r0,=SOURCE
	ldr	r1,=TARGET
	sub	r3,r0,#4
	ldr	r2,[r3]
	add	r2,r2,#1 // to ensure r2 can be divided exactly by 4
_CopyLoop:
	ldr	r3,[r0]
	str	r3,[r1]
	add	r0,r0,#4
	add	r1,r1,#4
	sub	r2,r2,#4
	teq	r2,#0
	beq	_EndCopy
	b		_CopyLoop
	
_EndCopy:
	ldr	r0,=TARGET
	mov	pc,r0
				
.section ".flash.data"
.section ".flash.bss"