u-boot-2014.10移植第27天----nand flash启动（五）

硬件平台：tq2440

开发环境：Ubuntu-3.11

u-boot版本：2014.10

本文允许转载，请注明出处：http://blog.csdn.net/fulinus

为实现nand flash启动，最好的方法是使用u-boot自身提供的SPL方式，就是借助另一个相对独立的u-boot-spl.bin执行文件，将u-boot.bin拷贝到SDRAM中去，再运行u-boot.bin。这样一来u-boot就可以再次重定向。我们这里首先尝试用一个老方法。

1、首先关闭“位置无关”的编译选项，在arch/arm/config.mk文件中，注释“pie”：

# needed for relocation# LDFLAGS_u-boot += -pie

2、修改基地址，在include/configs/tq2440.h配置文件中，修改CONFIG_SYS_TEXT_BASE：

#define CONFIG_SYS_TEXT_BASE 0x33F80000

3、在board/samsung/tq2440目录下添加nand_read_ll.c文件，nand_read_ll.c文件内容如下：

/* NAND FLASH控制器 */#define NFCONF  (*((volatile unsigned long *)0x4E000000))#define NFCONT  (*((volatile unsigned long *)0x4E000004))#define NFCMMD  (*((volatile unsigned long *)0x4E000008))#define NFADDR  (*((volatile unsigned long *)0x4E00000C))#define NFDATA  (*((volatile unsigned long *)0x4E000010))#define NFSTAT  (*((volatile unsigned long *)0x4E000020))static int is_boot_from_norflash(void){    int val;    volatile int *p = (volatile int *)0;    val = *p;    *p = 0x12345678;    if(*p == 0x12345678){        /* 写成功，是nand flash启动 */        *p = val;        return 0;    }else{        /* Nor flash 不能像内存一样写 */        return 1;    }}void nand_init_ll(void){#define TACLS 0#define TWRPH0  1#define TWRPH1  0    /* 设置时序 */    NFCONT = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4);    /* 使能Nand flash 控制器，初始化ECC, 禁止片选 */    NFCONT = (1<<4)|(1<<1)|(1<<0);}void clear_bss(void){    extern int __bss_start, __bss_end;    int *p = &__bss_start;    for(; p < &__bss_end; p++){        *p = 0;    }}static void nand_select(void){    NFCONT &= ~(1<<1);}static void nand_deselect(void){    NFCONT |= (1<<1);}static void nand_cmd(unsigned char cmd){    volatile int i;    NFCMMD = cmd;    for(i = 0; i < 10; i++);}static void nand_addr(unsigned int addr){    volatile int i;    unsigned int col = addr % 2048;    unsigned int page = addr / 2048;    NFADDR = col & 0xFF;        for(i = 0; i < 10; i++);    NFADDR = (col >> 8) & 0xFF;    for(i = 0; i < 10; i++);    NFADDR = page & 0xFF;    for(i = 0; i < 10; i++);    NFADDR = (page >> 8) & 0xFF;    for(i = 0; i < 10; i++);    NFADDR = (page >> 16) & 0xFF;    for(i = 0; i < 10; i++);}static void nand_wait_ready(void){    while(!(NFSTAT & 1));}static unsigned char nand_data(void){    return NFDATA;}static void nand_read_ll(unsigned int addr, unsigned char *buf, unsigned int len){    int i = 0;    int col = addr % 2048;    /* 1.选中 */    nand_select();    while(i < len)    {        /* 2.发出读命令:00h */        nand_cmd(0x00);        /* 3.发出地址指令 */        nand_addr(addr);        /* 4.发出读命令:30h */        nand_cmd(0x30);        /* 5.判断状态 */        nand_wait_ready();        /* 6.读数据 */        for(; (col < 2048) && (i < len); col++){            buf[i] = nand_data();            i++;            addr++;        }        col = 0;    }    /* 7.取消选中 */    nand_deselect();}void copy_code_to_sdram(unsigned char *src, unsigned char *dest, unsigned int len){    int i = 0;    /* 如果是Nor flash 启动 */    if(is_boot_from_norflash()){        while(i < len){            dest[i] = src[i];            i++;        }    }else{        nand_init_ll();        nand_read_ll((unsigned int)src, dest, len);    }}

4、修改board/samsung/tq2440目录下的Makefile文件：

obj-y   := tq2440.o+ obj-y   += nand_read_ll.oobj-y   += lowlevel_init.o

5、修改arch/arm/lib/crt0.S文件：

ENTRY(_main)


/*
 * Set up initial C runtime environment and call board_init_f(0).
 */


#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
        ldr     sp, =(CONFIG_SPL_STACK)
#else
        ldr     sp, =(CONFIG_SYS_INIT_SP_ADDR)
#endif
        bic     sp, sp, #7      /* 8-byte alignment for ABI compliance */
        mov     r2, sp
        sub     sp, sp, #GD_SIZE        /* allocate one GD above SP */
        bic     sp, sp, #7      /* 8-byte alignment for ABI compliance */
        mov     r9, sp          /* GD is above SP */


#if 1
__TEXT_BASE:
    .word CONFIG_SYS_TEXT_BASE
    
    mov r0, #0
    ldr r1, __TEXT_BASE


    ldr r2, __TEXT_BASE


    ldr r3, =__bss_end


    sub r2, r3, r2


    bl copy_code_to_sdram
    bl clear_bss


    ldr pc, =call_board_init_f


call_board_init_f:
    mov r0, #0
    bl board_init_f


        ldr     sp, [r9, #GD_START_ADDR_SP]     /* sp = gd->start_addr_sp */
        bic     sp, sp, #7      /* 8-byte alignment for ABI compliance */
        ldr     r9, [r9, #GD_BD]                /* r9 = gd->bd */
        sub     r9, r9, #GD_SIZE                /* new GD is below bd */


    ldr r1, __TEXT_BASE
    bl board_init_r
#else

        mov     r1, sp
        mov     r0, #0
clr_gd:
        cmp     r1, r2                  /* while not at end of GD */
        strlo   r0, [r1]                /* clear 32-bit GD word */
        addlo   r1, r1, #4              /* move to next */
        blo     clr_gd
#if defined(CONFIG_SYS_MALLOC_F_LEN) && !defined(CONFIG_SPL_BUILD)
        sub     sp, sp, #CONFIG_SYS_MALLOC_F_LEN
        str     sp, [r9, #GD_MALLOC_BASE]
#endif
        /* mov r0, #0 not needed due to above code */
        bl      board_init_f


#if ! defined(CONFIG_SPL_BUILD)


/*
 * Set up intermediate environment (new sp and gd) and call
 * relocate_code(addr_moni). Trick here is that we'll return
 * 'here' but relocated.
 */


        ldr     sp, [r9, #GD_START_ADDR_SP]     /* sp = gd->start_addr_sp */
        bic     sp, sp, #7      /* 8-byte alignment for ABI compliance */
        ldr     r9, [r9, #GD_BD]                /* r9 = gd->bd */
        sub     r9, r9, #GD_SIZE                /* new GD is below bd */


        adr     lr, here
        ldr     r0, [r9, #GD_RELOC_OFF]         /* r0 = gd->reloc_off */
        add     lr, lr, r0
        ldr     r0, [r9, #GD_RELOCADDR]         /* r0 = gd->relocaddr */
        b       relocate_code
here:


/* Set up final (full) environment */


        bl      c_runtime_cpu_setup     /* we still call old routine here */


        ldr     r0, =__bss_start        /* this is auto-relocated! */
        ldr     r1, =__bss_end          /* this is auto-relocated! */


        mov     r2, #0x00000000         /* prepare zero to clear BSS */


clbss_l:cmp     r0, r1                  /* while not at end of BSS */
        strlo   r2, [r0]                /* clear 32-bit BSS word */
        addlo   r0, r0, #4              /* move to next */
        blo     clbss_l


        bl coloured_LED_init
        bl red_led_on


        /* call board_init_r(gd_t *id, ulong dest_addr) */
        mov     r0, r9                  /* gd_t */
        ldr     r1, [r9, #GD_RELOCADDR] /* dest_addr */
        /* call board_init_r */
        ldr     pc, =board_init_r       /* this is auto-relocated! */


        /* we should not return here. */


#endif
#endif


ENDPROC(_main)

6、修改arch/arm/lib/board.c 文件中的board_init_f函数:

//void board_init_f(ulong bootflag)
unsigned int board_init_f(ulong bootflag)
。。。

    //addr -= gd->mon_len;
    //addr &= ~(4096 - 1);
    addr = CONFIG_SYS_TEXT_BASE;

。。。

    memcpy(id, (void *)gd, sizeof(gd_t));

    return (unsigned int)id;
} 

7、同时修改include/common.h头文件中board_init_f函数的声明：

//void  board_init_f(ulong);
unsigned int board_init_f(ulong);

8、修改连接脚本arch/arm/cpu/u-boot.lds文件，将nand_read_ll.c文件放在前4K字节中：

    .text :
    {
        *(.__image_copy_start)
        *(.vectors)
        CPUDIR/start.o (.text*)
        board/samsung/tq2440/lowlevel_init.o(.text*)
        board/samsung/tq2440/nand_read_ll.o(.text*)
        *(.text*)                           
    }  

9、修改arch/arm/config.mk文件，将checkarmreloc功能注释掉：

# ALL-y += checkarmreloc

10、编译

不成功，感觉这个方法很牵强，换一种；

明天继续；