boot.s

一些linux和uboot的学习笔记

@*************************************************
@***************XJTU YY_HONG**********************
@***************START BOOT TEST CODE**************


#include "AT91SAM9261_inc.h"

ABT_MODE = 0x17
FIQ_MODE = 0x11
IRQ_MODE = 0x12
SVC_MODE = 0X13
SYS_MODE = 0X1F
UND_MODE = 0x1B
USR_MODE = 0x10

I_BIT  =     0x80
F_BIT  =     0x40
@this text is the boot for VC9261 board
          .global start
	  .extern main
	  .extern sys_init
	  .org 0
start:
    B	  reset     
undef:    
    B	  undef
swi:
    B	  swi
pabt:
    B	  pabt
dabt:
    B     dabt
datalenth:
    .word 0x20000 
irq:
    B     irq_handle
fiq:
    B	  fiq
@STACK PUT TO THE END OF SDRAM

@SECOND SET pll
@THIRD SET SDRAM
@FORTH RESET STACK
SP_STACK = 0x20000
STACK_SIZE =0X500
reset:
	@FIRST SET STACK 
    ldr r0, =AT91C_WDTC_WDMR    @close the watch dog!
    ldr r1, =AT91C_WDTC_WDDIS 
    str r1, [r0]		

    LDR   r0, 	=SP_STACK
    MRS   r1,	cpsr
@    LDR   r2,	#ABT_MODE
    BIC   r1,	r1, #0x1f	
    ORR   r1,	r1, #ABT_MODE	
    MSR   cpsr,	r1
    MOV   r13, 	r0    

    SUB   r0, 	r0, #STACK_SIZE
    MRS	  r1,	cpsr
    BIC   r1,   r1, #0x1f
    ORR   r1,	r1, #UND_MODE
    MSR   cpsr, r1
    MOV   r13,  r0

    SUB   r0, 	r0, #STACK_SIZE
    MRS	  r1,	cpsr
    BIC   r1,   r1, #0x1f
    ORR   r1,	r1, #SVC_MODE
    MSr   cpsr, r1
    MOV   r13,  r0

    SUB   r0, 	r0, #STACK_SIZE
    MRS	  r1,	cpsr
    BIC   r1,   r1, #0x1f
    ORR   r1,	r1, #FIQ_MODE
    MSr   cpsr, r1
    MOV   r13,  r0

    SUB   r0, 	r0, #STACK_SIZE
    MRS	  r1,	cpsr
    BIC   r1,   r1, #0x1f
    ORR   r1,	r1, #IRQ_MODE
    MSr   cpsr, r1
    MOV   r13,  r0

    SUB   r0, 	r0, #STACK_SIZE
    MRS	  r1,	cpsr
    BIC   r1,   r1, #0x1f
    ORR   r1,	r1, #SYS_MODE
    BIC   r1,   r1, #0xc0   
    MSR   cpsr, r1
    MOV   r13,  r0
    
@test the led blink!
    LDR   r0,  	=0xfffff400 
    LDR   r1,	=0xc0018000 
    STR   r1,	[r0]

    LDR   r0,   =0xfffff410
    LDR   r1, 	=0xc0018000
    STR   r1,	[r0]	

    LDR   r0,   =0xfffff434 
    LDR   r1,   =0x00018000
    STR   r1,	[r0]

    LDR   r0,   =0xfffff430
    LDR   r1,	=0xc0000000
    STR   r1,	[r0]

@   LDR   r0,   =AT91C_BASE_SYS
@    .extern main
@    ldr   r0, =main
@    bx    r0
    BL    sys_init
    BL    main
handle:
    B     handle
@test the AIC interrupt
irq_handle:
    SUB	  r14,	r14, #4	
    STMFD r13!, {r0 - r12,r14}
    MRS   r14,  SPSR
    STMFD r13!, {r14}
     
    LDR   r0,	=AT91C_AIC_IVR 
    LDR   r1,   [r0]
    
    MOV   r14,  PC  
    BX    r1

    LDR   r1,   =0x0001
    LDR   r0,   =AT91C_AIC_EOICR 
    STR   r1,   [r0]
    LDMFD r13!,  {r14}
    MSR   SPSR, r14
    LDMFD r13!,	{r0 - r12, pc}^