init.s

xscale pxa255 bootloader 程序

	MACRO  
	CPWAIT
	MRC	  p15, 0, R0, c2, c0, 0
	MOV	  R0, R0
	SUB	  PC, PC, #4	
	MEND
	
	AREA	init, CODE, READONLY, ALIGN=5
	ENTRY
	


	B		Reset_Handler						; Reset here(0)
	B		Reset_Handler						; Undefined_Handler(1)
	B		Reset_Handler						; SWI_Handler(2)
	B		Reset_Handler						; Prefetch_Handler(3)
	B		Reset_Handler						; Abort_Handler(4)
	B		Reset_Handler						; Reserved vector(5)
	B		Reset_Handler						; IRQ_Handler(6)
	B		Reset_Handler						; FIQ interrupt vector(7)

Reset_Handler

	MOV	R0,#0xFFFFFFFF
	MCR	p15, 0, R0, c3, c0, 0			; Reset DAC
	CPWAIT
	MRC	p15, 0, R0, c1, c0, 0
	ORR	R0, R0, #0x1800					; Enable I-Cache
	MCR	p15, 0, R0, c1, c0, 0
	CPWAIT
	

	LDR	SP, =0xA0800000					; End of SDRAM(8M)
	
		;init sdram
	LDR	R1, =0x981
	MOV	R0, #0x48000000
	STR	R1, [R0,#0]							; MDCNFG=0x981(8M SDRAM)
	LDR	R2, =0x0001c030
	STR	R2, [r0,#4]							; MDREFR=MEM_CLK_100M
	MOV	R3, #0
	STR	R3, [r0,#0x40]						; MDMRS=0


	MOV	R0,PC
	TST	R0, #0x80000000
	BNE	SYS_NOCPY					; Jump if R0>0x80000000


	
	ADR 	R0,  Reset_Handler
	ADR	 	R4,  CInitData
	LDR     R1,  =Reset_Handler
	LDR     R2,  [R4]    ;END OF ROM

ROMTORAM
	CMP         r1, r2                  ; Copy code to sdarm
	LDRCC       r3, [r0], #4
	STRCC       r3, [r1], #4
	BCC         ROMTORAM	
	
	LDR         R0,  =SYS_NOCPY  ; jump to sdram
	MOV         PC,  R0

SYS_NOCPY 
      
    ; INIT C CODE   
	add     r2, pc,#-(8+.-CInitData)  ; @ where to read values (relative)
	ldmia   r2, {r0, r1, r3, r4}
	
	cmp         r0, r1                  ; Check that they are different
	beq         EndRW
LoopRW	
	cmp         r1, r3                  ; Copy init data
	ldrcc       r2, [r0], #4
	strcc       r2, [r1], #4
	bcc         LoopRW
EndRW

	mov         r2, #0
LoopZI	
	cmp         r3, r4                  ; Zero init
	strcc       r2, [r3], #4
	bcc         LoopZI
 
	b           EndInitC
                
CInitData
 	IMPORT      |Image$$RO$$Limit|      ; End of ROM code (=start of ROM data)
	IMPORT      |Image$$RW$$Base|       ; Base of RAM to initialise
	IMPORT      |Image$$ZI$$Base|       ; Base and limit of area
	IMPORT      |Image$$ZI$$Limit|      ; Top of zero init segment
	
	DCD     |Image$$RO$$Limit|      ; End of ROM code (=start of ROM data)
 	DCD     |Image$$RW$$Base|       ; Base of RAM to initialise
 	DCD     |Image$$ZI$$Base|       ; Base and limit of area
 	DCD     |Image$$ZI$$Limit|      ; Top of zero init segment
 	
EndInitC

	IMPORT Main
	
 	B		Main
 	

	END