埋め込み学習-uboot-lesson 9.2-C点灯LED

/********************************************
*file name: main.c
*author   : stone
*date     : 2016.6.30
*function :   LED   
*********************************************/
#define GPMCON (*(volatile unsigned long *)0x7F008820)
#define GPMDAT (*(volatile unsigned long *)0x7F008824) 

int gboot_main()
{
 GPMCON = 0x1111; 
 GPMDAT = 0x00; //     

 return 0;
}

ldr pc,=gboot_main @   gboot_main

all: start.o mem.o main.o
    arm-linux-ld -Tgboot.lds -o gboot.elf $^
    arm-linux-objcopy -O binary gboot.elf gboot.bin

%.o : %.S
    arm-linux-gcc -g -c $^

%.o : %.c
    arm-linux-gcc -g -c $^

.PHONY: clean
clean:
    rm *.o *.elf *.bin

@****************************
@file name: start.S
@author   : stone
@date     : 2016.6.30
@function : 
@          
@           SVC  
@              
@             
@           MMU
@                 
@           LED
@              
@              
@             
@             
@           BSS 
@            gboot_main
@****************************

.text
.global _start  @ _start       
_start:
        b   reset                       
        ldr pc, _undefined_instruction  
        ldr pc, _software_interrupt     
        ldr pc, _prefetch_abort         
        ldr pc, _data_abort             
        ldr pc, _not_used               
        ldr pc, _irq                    
        ldr pc, _fiq

_undefined_instruction: .word undefined_instruction
_software_interrupt:    .word software_interrupt
_prefetch_abort:    .word prefetch_abort
_data_abort:        .word data_abort
_not_used:      .word not_used
_irq:           .word irq
_fiq:           .word fiq                   

undefined_instruction:  @         
        nop

software_interrupt:     @   
        nop

prefetch_abort:         @      
        nop

data_abort:             @      
        nop

not_used:               @  
        nop

irq:                    @  
        nop

fiq:                    @    
        nop

reset:                          @reset
    bl set_svc              @   SVC  
    bl set_peri_port        @        
    bl disable_watchdog     @     
    bl disable_interrupt    @    
    bl disable_mmu          @  mmu
    bl init_clock           @     
    bl mem_init             @     
    bl copy_to_ram          @    
    bl init_stack           @    
    bl clean_bss            @   bss 
    ldr pc,=gboot_main      @   gboot_main
    @bl light_led           @  LED

set_svc:        
    mrs r0, cpsr        @    cpsr   
    bic r0, r0, #0x1f @  5   M[4:0]   
    orr r0, r0, #0xd3 @0b10011    16   0x13       irq fiq，       0b11010011 0xd3 
    msr cpsr, r0        @    cpsr   
    mov pc, lr              @  

set_peri_port:
    ldr r0, =0x70000000     @   
    orr r0, r0, #0x13 @256MB
    mcr p15,0,r0,c15,c2,4   @  cp15
    mov pc, lr

#define pwTCON 0x7E004000 @WTCON   
disable_watchdog: 
        ldr r0, =pwTCON         @      R0
        mov r1, #0x0 @ 0,     
        str r1,[r0]     
        mov pc,lr

disable_interrupt:
        mvn r1,#0x0 @0x0   ， r1
        ldr r0,=0x71200014      @VIC0
        str r1,[r0]
        ldr r0,=0x71300014      @VIC1
        str r1,[r0]
        mov pc,lr

disable_mmu:
        mcr p15,0,r0,c7,c7,0    @ ICACHE  DCACHE   
    mrc p15,0,r0,c1,c0,0    @read control register
    bic r0,r0,#0x00000007 @mmu   dcache  
    mcr p15,0,r0,c1,c0,0    @write control register
    mov pc,lr

#define CLK_DIV0 0x7e00f020
#define CLK_SRC 0x7e00f01c
#define OTHERS 0x7e00f900
#define MPLL_CON 0X7E00F010
#define APLL_CON 0X7E00F00c
#define PLL_VAL ((1<<31)|(266<<16)|(3<<8)|(1<<0))
#define DIV_VAL ((0X0<<0)|(0X1<<9)|(0X1<<8)|(0X3<<12))
init_clock:
ldr r0,=CLK_DIV0        @      
    ldr r1,=DIV_VAL
    str r1,[r0]

    ldr r0,=OTHERS      @          7  0  6  0(     )
    ldr r1,[r0]
    bic r1,r1,#0xc0
    str r1,[r0]

    ldr r0,=APLL_CON    @APLL   533Mhz
    ldr r1,=PLL_VAL
    str r1,[r0]

    ldr r0,=MPLL_CON    @MPLL   533Mhz
    ldr r1,=PLL_VAL
    str r1,[r0]

    ldr r0, =CLK_SRC    @      APLL MPLL    
    mov r1, #0x3 @APLL MPLL
    str r1, [r0]        
    mov pc,lr

copy_to_ram:
        ldr r0, =0x0c000000     @    
        ldr r1, =0x50008000     @    
        add r3, r0, #1024*4 @  4KB  

copy_loop:
        ldr r2, [r0], #4 @ r0     
        str r2, [r1], #4 @  r1 
        cmp r0, r3              @  r0          
    bne copy_loop
        mov pc, lr

init_stack:
    ldr sp,=0x54000000      @50000000 + 64 
    mov pc,lr

clean_bss:
    ldr r0,=bss_start
    ldr r1,=bss_end
    cmp r0,r1               @ r0 r1    ，    ，      ，        
    moveq pc,lr             @    ，    

clean_loop:
    mov r2,#0
    str r2,[r0],#4
    cmp r0,r1
    bne clean_loop
    mov pc,lr

#define GPMCON 0x7F008820 @     
#define GPMDAT 0x7F008824 @      
light_led:
    ldr r0,=GPMCON
    ldr r1,=0x1111          @    
    str r1,[r0]

    ldr r0,=GPMDAT
    ldr r1,=0x00            @     
    str r1,[r0] 
    mov pc,lr