EasyARM-iMX257_U-Boot源代码移植分析

mx25_3stack_config    :    unconfig

@$(MKCONFIG) $(@:_config=) arm arm926ejs mx25_3stack freescale mx25

mx28_config : unconfig

@$(MKCONFIG) $(@:_config=) arm arm926ejs mx28 freescale mx28

#./mkconfig mx25_3stack arm arm926ejs mx25_3stack freescale mx25

# $0         $1         $2     $3            $4        $5     $6

APPEND=no    # Default: Create new config file

BOARD_NAME=""    # Name to print in make output

[ "${BOARD_NAME}" ] || BOARD_NAME="$1"

#=> 单板的名字：BOARD_NAME = mx25_3stack

echo "Configuring for ${BOARD_NAME} board..."

#=> 接下来会打印这句话

# Create link to architecture specific headers

    cd ./include

    rm -f asm

    ln -s asm-$2 asm

#=> ln -s asm-arm asm

# 在include下生成一个指向asm-arm的链接文件

rm -f asm-$2/arch

#=> rm -f asm-arm arch

ln -s ${LNPREFIX}arch-$6 asm-$2/arch

#=> ln -s arch-mx25 asm-arm/arch

# 在include/asm-arm 下生成一个指向arch-mx25的链接文件

if [ "$2" = "arm" ] ; then

    rm -f asm-$2/proc

    ln -s ${LNPREFIX}proc-armv asm-$2/proc

#=> ln -s arch-mx25 asm-arm/arch

# 在include/asm-arm 下生成一个指向asm-arm/proc的链接文件

fi

#

# Create include file for Make

#

echo "ARCH = $2" > config.mk

echo "CPU = $3" >> config.mk

echo "BOARD = $4" >> config.mk

# 生成config.mk 文件 内容如下：

# ARCH = arm

# CPU = arm926ejs

# BOARD = mx25_3stack

[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk

# $5 = freescale 在config.mk中添加

# VENDOR = freescale

[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk

# $6 = mx25 在config.mk中添加

# SOC = mx25

# Create board specific header file

    > config.h        # Create new config file

echo "/* Automatically generated - do not edit */" >>config.h

echo "#include <configs/$1.h>" >>config.h

echo "#include <asm/config.h>" >>config.h

#新建一个config.h文件，并添加以上信息

exit 0

157 # load ARCH, BOARD, and CPU configuration

158 include $(obj)include/config.mk

159 export    ARCH CPU BOARD VENDOR SOC

#紧跟上面的配置过程，这里mkconfig.mk就是上一步生成的一些开发板的相关信息

172 OBJS = cpu/$(CPU)/start.o

# OBJS = cpu/arm926ejs/start.o

186 LIBS = lib_generic/libgeneric.a

191 LIBS += cpu/$(CPU)/lib$(CPU).a

# LIBS += cpu/ arm926ejs/lib arm926ejs.a

254 LIBBOARD = board/$(BOARDDIR)/lib$(BOARD).a

255 LIBBOARD := $(addprefix $(obj),$(LIBBOARD))

# LIBBOARD = board/ freescale /mx25_3stack/libmx25_3stack.a

295 ALL += $(obj)u-boot.srec $(obj)u-boot.bin

$ (obj)System.map $(U_BOOT_NAND) $(U_BOOT_ONENAND)

296 all:        $(ALL)

280 U_BOOT_NAND = $(obj)u-boot-nand.bin

285 U_BOOT_ONENAND = $(obj)u-boot-onenand.bin

302 $(obj)u-boot.srec:    $(obj)u-boot

303 $(OBJCOPY) -O srec $< $@

305 $(obj)u-boot.bin:    $(obj)u-boot

306 $(OBJCOPY) ${OBJCFLAGS} -O binary $< $@

#这个u-boot是一个elf格式 的可执行文件

450 $(obj)System.map:    $(obj)u-boot

451 @$(call SYSTEM_MAP,$<) > $(obj)System.map

LDSCRIPT := $(SRCTREE)/board/$(VENDOR)/$(BOARD)/u-boot.lds

TEXT_BASE = 0x83F00000

    . = 0x00000000;

#从config.mk知，下面的数据从TEXT_BASE = 0x83F00000开始排放

    . = ALIGN(4);

    .text     :

    {

#代码段排放顺序

     board/freescale/mx25_3stack/dcdheader.o (.text)

     cpu/arm926ejs/start.o    (.text)

     *(.text)

    }

#所有文件的只读数据段

    . = ALIGN(4);

    .rodata : { *(.rodata) }

#所有文件的数据段

    . = ALIGN(4);

    .data : { *(.data) }

    . = ALIGN(4);

    .got : { *(.got) }

    . = .;

    __u_boot_cmd_start = .;

#所有文件的u_boot_cmd段，u-boot自定义的段

    .u_boot_cmd : { *(.u_boot_cmd) }

    __u_boot_cmd_end = .;

    . = ALIGN(4);

    __bss_start = .;

    .bss : { *(.bss) }

    _end = .;

.extern reset

#define DCDGEN(i,type, addr, data) \

dcd_##i:            ;\

.long type            ;\

.long addr            ;\

.long data

.globl _initheader

_initheader:

    b    reset

    .org 0x400

app_code_jump_v:    .long reset

app_code_barker:    .long 0xB1

app_code_csf:        .long 0

hwcfg_ptr_ptr:        .long hwcfg_ptr

super_root_key:        .long 0

hwcfg_ptr:        .long dcd_data

app_dest_ptr:        .long TEXT_BASE

dcd_data:        .long 0xB17219E9

#ifdef MXC_MEMORY_MDDR

dcd_len:        .long 12*15

#else

dcd_len:        .long 12*24

#endif

/* WEIM config-CS5 init -- CPLD */

DCDGEN( 1, 4, 0xB8002050, 0x0000D843) /* CS5_CSCRU */

DCDGEN( 2, 4, 0xB8002054, 0x22252521) /* CS5_CSCRL */

DCDGEN( 3, 4, 0xB8002058, 0x22220A00) /* CS5_CSCRA */

#ifdef MXC_MEMORY_MDDR

/* MDDR init */

DCDGEN( 4, 4, 0xB8001010, 0x00000004) /* enable mDDR */

DCDGEN( 5, 4, 0xB8001000, 0x92100000) /* precharge command */

DCDGEN( 6, 1, 0x80000400, 0x12344321) /* precharge all dummy write */

DCDGEN( 7, 4, 0xB8001000, 0xA2100000) /* auto-refresh command */

DCDGEN( 8, 4, 0x80000000, 0x12344321) /* dummy write for refresh */

DCDGEN( 9, 4, 0x80000000, 0x12344321) /* dummy write for refresh */

DCDGEN(10, 4, 0xB8001000, 0xB2100000) /* Load Mode Reg command - cas=3 bl=8 */

DCDGEN(11, 1, 0x80000033, 0xda)    /* dummy write -- address has the mode bits */

DCDGEN(12, 1, 0x81000000, 0xff) /* dummy write -- address has the mode bits */

DCDGEN(13, 4, 0xB8001000, 0x82216880)

DCDGEN(14, 4, 0xB8001004, 0x00295729)

#else

/* DDR2 init */

DCDGEN( 4, 4, 0xB8001004, 0x0076E83A)    /* initial value for ESDCFG0 */

DCDGEN( 5, 4, 0xB8001010, 0x00000204)    /* ESD_MISC */

DCDGEN( 6, 4, 0xB8001000, 0x92210000)    /* CS0 precharge command */

DCDGEN( 7, 4, 0x80000f00, 0x12344321)    /* precharge all dummy write */

DCDGEN( 8, 4, 0xB8001000, 0xB2210000)    /* Load Mode Register command */

DCDGEN( 9, 1, 0x82000000, 0xda)        /* dummy write Load EMR2 */

DCDGEN(10, 1, 0x83000000, 0xda)        /* dummy write Load EMR3 */

DCDGEN(11, 1, 0x81000400, 0xda)        /* dummy write Load EMR1; enable DLL */

DCDGEN(12, 1, 0x80000333, 0xda)        /* dummy write Load MR; reset DLL */

DCDGEN(13, 4, 0xB8001000, 0x92210000)    /* CS0 precharge command */

DCDGEN(14, 1, 0x80000400, 0x12345678)    /* precharge all dummy write */

DCDGEN(15, 4, 0xB8001000, 0xA2210000)    /* select manual refresh mode */

DCDGEN(16, 4, 0x80000000, 0x87654321)    /* manual refresh */

DCDGEN(17, 4, 0x80000000, 0x87654321)    /* manual refresh twice */

DCDGEN(18, 4, 0xB8001000, 0xB2210000)    /* Load Mode Register command */

DCDGEN(19, 1, 0x80000233, 0xda)        /* Load MR; CL=3, BL=8, end DLL reset */

DCDGEN(20, 1, 0x81000780, 0xda)        /* Load EMR1; OCD default */

DCDGEN(21, 1, 0x81000400, 0xda)        /* Load EMR1; OCD exit */

DCDGEN(22, 4, 0xB8001000, 0x82216080)    /* normal mode */

DCDGEN(23, 4, 0x43FAC454, 0x00001000)    /* IOMUXC_SW_PAD_CTL_GRP_DDRTYPE(1-5) */

#endif

DCDGEN(99, 4, 0x53F80008, 0x20034000) /* CLKCTL ARM=400 AHB=133 */

card_cfg:    .long UBOOT_IMAGE_SIZE

.globl reset

reset:

/** set the cpu to SVC32 mode 设置为SVC32管理模式*/

    mrs    r0,cpsr

    bic    r0,r0,#0x1f

    orr    r0,r0,#0xd3

    msr    cpsr,r0

/ * CPU的初始化

屏蔽中断

初始化SDRAM

设置时钟*/

bl    cpu_init_crit

/*重定位 */

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 /* 设置栈 */

    ldr    r2, _armboot_start

    ldr    r3, _bss_start

    sub    r2, r3, r2        /* r2 <- size of armboot */

    add    r2, r0, r2        /* r2 <- source end address */

/* 拷贝代码 flash => SDRAM */

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

/* 设置栈 */

/* Set up the stack                         */

stack_setup:

    ldr    r0, _TEXT_BASE         /* upper 128 KiB: relocated uboot */

    sub    r0, r0, #CONFIG_SYS_MALLOC_LEN    /* malloc area */

    sub    r0, r0, #CONFIG_SYS_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 */

/* 清除bss段 */

clear_bss:

    ldr    r0, _bss_start        /* find start of bss segment */

    ldr    r1, _bss_end        /* stop here */

    mov    r2, #0x00000000        /* clear */

bl coloured_LED_init //调用心脏LED灯初始化

bl red_LED_on //点亮红色LED灯

/* 跳转到第二阶段，用C语言实现的更多的功能*/

ldr    pc, _start_armboot

/* 1.falsh_init()会识别出是falsh的类别 */

/* configure available FLASH banks */

    display_flash_config (flash_init ());

/* 2.对flash的初始化，读写功能 */

#if defined(CONFIG_CMD_NAND)

    puts ("NAND: ");

    nand_init();        /* go init the NAND */

#endif

/* 3环境变量的初始化 */

/* initialize environment */

    env_relocate ();

/* 4串口初始化 */

serial_initialize();

/* 5. 网络IP设置 IP Address */

    gd->bd->bi_ip_addr = getenv_IPaddr ("ipaddr");

/*6. 最终进过一系列的初始化，进入主循环 ，等要用户在u-boot命令后输入命令*/

/* main_loop() can return to retry autoboot, if so just run it again. */

    for (;;) {

        main_loop ();

    }

/*主循环中主要就是对命令的接收与解析，运行相应的函数

readline(‘读入串口输入的命令‘);

run_command;

所以也可以说U-Boot的核心就是这些命令

*/

#include <image.h>

#include <malloc.h>

#include <u-boot/zlib.h>

#include <bzlib.h>

#include <environment.h>

#include <lmb.h>

#include <linux/ctype.h>

#include <asm/byteorder.h>

int do_hello (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])

{

    int i = 0;

    printf("hello,Lover雪!!!\nthe argcs are \n");

    for(i = 0 ; i<argc ; i++)

        printf("argv[%d]: %s\n",i,argv[i]);

    return 0;

}

U_BOOT_CMD(

    hello,    CONFIG_SYS_MAXARGS,    1,    do_hello,

    "This is a user defined command hello,Lover雪!!!",

    "hello,long help ......\n"

    );

COBJS-y += cmd_hello.o