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最近在做U-BOOT移植到S3C2410的移植,但是发现编译了U-BOOT-1.2.0下载的开发板上面以后,完全没反应。开发板是没有norflash的,手里也只有一根wiggler,所以也不知道怎么单步调试。所以就想到的传说中的“点灯大法”,就是在/cpu/arm920t/start.S中用汇编写一个死循环,在进行完CPU初始化以后,不断的点亮一个LED,但是发现这样也不成功。实在是没办法了。把start.s中的代码发上来。
- #include <config.h>
- #include <version.h>
- /*
- *************************************************************************
- *
- * Jump vector table as in table 3.1 in [1]
- *
- *************************************************************************
- */
- .globl _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
- .balignl 16,0xdeadbeef
- /*
- *************************************************************************
- *
- * Startup Code (reset vector)
- *
- * do important init only if we don't start from memory!
- * relocate armboot to ram
- * setup stack
- * jump to second stage
- *
- *************************************************************************
- */
- _TEXT_BASE:
- .word TEXT_BASE
- .globl _armboot_start
- _armboot_start:
- .word _start
- /*
- * These are defined in the board-specific linker script.
- */
- .globl _bss_start
- _bss_start:
- .word __bss_start
- .globl _bss_end
- _bss_end:
- .word _end
- #ifdef CONFIG_USE_IRQ
- /* IRQ stack memory (calculated at run-time) */
- .globl IRQ_STACK_START
- IRQ_STACK_START:
- .word 0x0badc0de
- /* IRQ stack memory (calculated at run-time) */
- .globl FIQ_STACK_START
- FIQ_STACK_START:
- .word 0x0badc0de
- #endif
- /*
- * the actual reset code
- */
- reset:
- /*
- * set the cpu to SVC32 mode
- */
- mrs r0,cpsr
- bic r0,r0,#0x1f
- orr r0,r0,#0xd3
- msr cpsr,r0
- /* turn off the watchdog */
- #if defined(CONFIG_S3C2400)
- # define pWTCON 0x15300000
- # define INTMSK 0x14400008 /* Interupt-Controller base addresses */
- # define CLKDIVN 0x14800014 /* clock divisor register */
- #elif defined(CONFIG_S3C2410)
- # define pWTCON 0x53000000
- # define INTMSK 0x4A000008 /* Interupt-Controller base addresses */
- # define INTSUBMSK 0x4A00001C
- # define CLKDIVN 0x4C000014 /* clock divisor register */
- #endif
- #if defined(CONFIG_S3C2400) || defined(CONFIG_S3C2410)
- ldr r0, =pWTCON
- mov r1, #0x0
- str r1, [r0]
- /*
- * mask all IRQs by setting all bits in the INTMR - default
- */
- mov r1, #0xffffffff
- ldr r0, =INTMSK
- str r1, [r0]
- # if defined(CONFIG_S3C2410)
- ldr r1, =0x3ff
- ldr r0, =INTSUBMSK
- str r1, [r0]
- # endif
- /* FCLK:HCLK:PCLK = 1:2:4 */
- /* default FCLK is 120 MHz ! */
- ldr r0, =CLKDIVN
- mov r1, #3
- str r1, [r0]
- #endif /* CONFIG_S3C2400 || CONFIG_S3C2410 */
- /*
- * we do sys-critical inits only at reboot,
- * not when booting from ram!
- */
- #ifndef CONFIG_SKIP_LOWLEVEL_INIT
- bl cpu_init_crit
- #endif
- /*这是我自己加的代码*************************
- *****************************************/
- #define GPFCON 0x56000050
- #define GPFDAT 0x56000054
- mov r1, #0x0100
- ldr r0, =GPFCON
- str r1,[r0]
- led:
- mov r1, #0x10
- ldr r0,=GPFDAT
- str r1,[r0]
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- nop
- mov r1,#0x00
- #ifndef CONFIG_SKIP_RELOCATE_UBOOT
- relocate: /* relocate U-Boot to RAM */
- adr r0, _start /* r0 <- current position of code */
- ldr r1, _TEXT_BASE /* test if we run from flash or RAM */
- cmp r0, r1 /* don't reloc during debug */
- beq stack_setup
- ldr r2, _armboot_start
- ldr r3, _bss_start
- sub r2, r3, r2 /* r2 <- size of armboot */
- add r2, r0, r2 /* r2 <- source end address */
- copy_loop:
- ldmia r0!, {r3-r10} /* copy from source address [r0] */
- stmia r1!, {r3-r10} /* copy to target address [r1] */
- cmp r0, r2 /* until source end addreee [r2] */
- ble copy_loop
- #endif /* CONFIG_SKIP_RELOCATE_UBOOT */
- /* Set up the stack */
- stack_setup:
- ldr r0, _TEXT_BASE /* upper 128 KiB: relocated uboot */
- sub r0, r0, #CFG_MALLOC_LEN /* malloc area */
- sub r0, r0, #CFG_GBL_DATA_SIZE /* bdinfo */
- #ifdef CONFIG_USE_IRQ
- sub r0, r0, #(CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ)
- #endif
- sub sp, r0, #12 /* leave 3 words for abort-stack */
- clear_bss:
- ldr r0, _bss_start /* find start of bss segment */
- ldr r1, _bss_end /* stop here */
- mov r2, #0x00000000 /* clear */
- clbss_l:str r2, [r0] /* clear loop... */
- add r0, r0, #4
- cmp r0, r1
- ble clbss_l
- #if 0
- /* try doing this stuff after the relocation */
- ldr r0, =pWTCON
- mov r1, #0x0
- str r1, [r0]
- /*
- * mask all IRQs by setting all bits in the INTMR - default
- */
- mov r1, #0xffffffff
- ldr r0, =INTMR
- str r1, [r0]
- /* FCLK:HCLK:PCLK = 1:2:4 */
- /* default FCLK is 120 MHz ! */
- ldr r0, =CLKDIVN
- mov r1, #3
- str r1, [r0]
- /* END stuff after relocation */
- #endif
- ldr pc, _start_armboot
- _start_armboot: .word start_armboot
- /*
- *************************************************************************
- *
- * CPU_init_critical registers
- *
- * setup important registers
- * setup memory timing
- *
- *************************************************************************
- */
- #ifndef CONFIG_SKIP_LOWLEVEL_INIT
- cpu_init_crit:
- /*
- * flush v4 I/D caches
- */
- mov r0, #0
- mcr p15, 0, r0, c7, c7, 0 /* flush v3/v4 cache */
- mcr p15, 0, r0, c8, c7, 0 /* flush v4 TLB */
- /*
- * disable MMU stuff and caches
- */
- mrc p15, 0, r0, c1, c0, 0
- bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS)
- bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM)
- orr r0, r0, #0x00000002 @ set bit 2 (A) Align
- orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache
- mcr p15, 0, r0, c1, c0, 0
- /*
- * before relocating, we have to setup RAM timing
- * because memory timing is board-dependend, you will
- * find a lowlevel_init.S in your board directory.
- */
- mov ip, lr
- bl lowlevel_init
- mov lr, ip
- mov pc, lr
- #endif /* CONFIG_SKIP_LOWLEVEL_INIT */
- /*
- *************************************************************************
- *
- * Interrupt handling
- *
- *************************************************************************
- */
- @
- @ IRQ stack frame.
- @
- #define S_FRAME_SIZE 72
- #define S_OLD_R0 68
- #define S_PSR 64
- #define S_PC 60
- #define S_LR 56
- #define S_SP 52
- #define S_IP 48
- #define S_FP 44
- #define S_R10 40
- #define S_R9 36
- #define S_R8 32
- #define S_R7 28
- #define S_R6 24
- #define S_R5 20
- #define S_R4 16
- #define S_R3 12
- #define S_R2 8
- #define S_R1 4
- #define S_R0 0
- #define MODE_SVC 0x13
- #define I_BIT 0x80
- /*
- * use bad_save_user_regs for abort/prefetch/undef/swi ...
- * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
- */
- .macro bad_save_user_regs
- sub sp, sp, #S_FRAME_SIZE
- stmia sp, {r0 - r12} @ Calling r0-r12
- ldr r2, _armboot_start
- sub r2, r2, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
- sub r2, r2, #(CFG_GBL_DATA_SIZE+8) @ set base 2 words into abort stack
- ldmia r2, {r2 - r3} @ get pc, cpsr
- add r0, sp, #S_FRAME_SIZE @ restore sp_SVC
- add r5, sp, #S_SP
- mov r1, lr
- stmia r5, {r0 - r3} @ save sp_SVC, lr_SVC, pc, cpsr
- mov r0, sp
- .endm
- .macro irq_save_user_regs
- sub sp, sp, #S_FRAME_SIZE
- stmia sp, {r0 - r12} @ Calling r0-r12
- add r8, sp, #S_PC
- stmdb r8, {sp, lr}^ @ Calling SP, LR
- str lr, [r8, #0] @ Save calling PC
- mrs r6, spsr
- str r6, [r8, #4] @ Save CPSR
- str r0, [r8, #8] @ Save OLD_R0
- mov r0, sp
- .endm
- .macro irq_restore_user_regs
- ldmia sp, {r0 - lr}^ @ Calling r0 - lr
- mov r0, r0
- ldr lr, [sp, #S_PC] @ Get PC
- add sp, sp, #S_FRAME_SIZE
- subs pc, lr, #4 @ return & move spsr_svc into cpsr
- .endm
- .macro get_bad_stack
- ldr r13, _armboot_start @ setup our mode stack
- sub r13, r13, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
- sub r13, r13, #(CFG_GBL_DATA_SIZE+8) @ reserved a couple spots in abort stack
- str lr, [r13] @ save caller lr / spsr
- mrs lr, spsr
- str lr, [r13, #4]
- mov r13, #MODE_SVC @ prepare SVC-Mode
- @ msr spsr_c, r13
- msr spsr, r13
- mov lr, pc
- movs pc, lr
- .endm
- .macro get_irq_stack @ setup IRQ stack
- ldr sp, IRQ_STACK_START
- .endm
- .macro get_fiq_stack @ setup FIQ stack
- ldr sp, FIQ_STACK_START
- .endm
- /*
- * exception handlers
- */
- .align 5
- undefined_instruction:
- get_bad_stack
- bad_save_user_regs
- bl do_undefined_instruction
- .align 5
- software_interrupt:
- get_bad_stack
- bad_save_user_regs
- bl do_software_interrupt
- .align 5
- prefetch_abort:
- get_bad_stack
- bad_save_user_regs
- bl do_prefetch_abort
- .align 5
- data_abort:
- get_bad_stack
- bad_save_user_regs
- bl do_data_abort
- .align 5
- not_used:
- get_bad_stack
- bad_save_user_regs
- bl do_not_used
- #ifdef CONFIG_USE_IRQ
- .align 5
- irq:
- get_irq_stack
- irq_save_user_regs
- bl do_irq
- irq_restore_user_regs
- .align 5
- fiq:
- get_fiq_stack
- /* someone ought to write a more effiction fiq_save_user_regs */
- irq_save_user_regs
- bl do_fiq
- irq_restore_user_regs
- #else
- .align 5
- irq:
- get_bad_stack
- bad_save_user_regs
- bl do_irq
- .align 5
- fiq:
- get_bad_stack
- bad_save_user_regs
- bl do_fiq
- #endif
复制代码
顺便把接口的电路也发上来吧。
[ 本帖最后由 骄傲的唐 于 2009-2-17 21:56 编辑 ] |
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