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  • S5P4418 uboot 分析

    瘋耔新浪微博:   http://weibo.com/cpjphone

    一:

    1◑ 从链接脚本文件u-boot.lds('/opt/4418-source/android/u-boot' )中可以找到代码的起始:

    OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
    OUTPUT_ARCH(arm)
    ENTRY(_stext)
    SECTIONS
    {
     . = 0x00000000;
     . = ALIGN(4);
     .text :
     {
      *(.__image_copy_start)
      arch/arm/cpu/slsiap/s5p4418/start.o (.text*)
      *(.text*)
     }

    从中知道程序的入口点是_start,定位于arch/arm/cpu/slsiap/s5p4418/start.o (即u-boot启动的第一阶段)。

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    2◑ 下面我们来仔细分析一下 start.S。(请对照数据手册阅读源码):

    /*
     * armboot - Startup Code for NXPxxxx/ARM Cortex CPU-core
     */
    
    #include <asm-offsets.h>
    #include <config.h>
    #include <version.h>
    #include <asm/system.h>
    #include <linux/linkage.h>
    
    /*
     *************************************************************************
     *
     * Exception vectors as described in ARM reference manuals
     *
     * replace arm/lib/vectors.S
     *
     *************************************************************************
     */
        .globl    _stext
    _stext:
        b     reset                //u-boot的主入口,跳入了后面的reset                
        ldr    pc, _undefined_instruction
        ldr    pc, _software_interrupt        //这些是跳转向量表,和芯片的体系结构有关
        ldr    pc, _prefetch_abort
        ldr    pc, _data_abort
        ldr    pc, _not_used            // ldr语句的意思是将第二个操作数(如:_undefined_instruction)指向的地址数据传给PC
        ldr    pc, _irq
        ldr    pc, _fiq
    
    /* ldr语句的意思是将第二个操作数(如:_undefined_instruction)指向的地址数据传给PC,undefined_instruction 为地址, 即后面标号所对的偏移地址数据  */
    _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        //16字节对齐,并以0xdeadbeef填充,它是个Magic number。
    
    /*
     *************************************************************************
     *
     * Text and section base
     *
     *************************************************************************
     */
    
    .globl TEXT_BASE
    TEXT_BASE:
        .word    CONFIG_SYS_TEXT_BASE        //这些和上面的一样,定义一个4字节的空间存放地址
    
    /*
     * These are defined in the board-specific linker script.
     */
    .globl _bss_start_ofs
    _bss_start_ofs:
        .word __bss_start - _stext
    
    .globl _bss_end_ofs
    _bss_end_ofs:
        .word __bss_end - _stext
    
    .globl _end_ofs
    _end_ofs:
        .word _end - _stext
    
    /*
     *************************************************************************
     *
     * Reset handling    代码从这里开始执行
     *
     *************************************************************************
     */
    
        .globl reset
    
    reset:
        bl    save_boot_params
        /*
         * set the cpu to SVC32 mode        让系统进入SVC(管理)员
         */
        mrs    r0, cpsr
        bic    r0, r0, #0x1f
        orr    r0, r0, #0xd3
        msr    cpsr,r0
    
        /* the mask ROM code should have PLL and others stable */
    #ifndef CONFIG_SKIP_LOWLEVEL_INIT
        bl    cpu_init_cp15
        bl    cpu_init_crit
    #endif
    
    #ifdef CONFIG_RELOC_TO_TEXT_BASE
    relocate_to_text:
        /*
         * relocate u-boot code on memory to text base
         * for nexell arm core (add by jhkim)
         */
        adr    r0, _stext                /* 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 clear_bss
    
        ldr    r2, _bss_start_ofs
        add    r2, r0, r2                /* r2 <- source end address         */
    
    copy_loop_text:
        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_text
    
        ldr    r1, TEXT_BASE            /* restart at text base */
        mov pc, r1
    
    clear_bss:
        ldr    r0, _bss_start_ofs
        ldr    r1, _bss_end_ofs
        ldr    r4, TEXT_BASE            /* text addr */
        add    r0, r0, r4
        add    r1, r1, r4
        mov    r2, #0x00000000            /* clear */
    
    clbss_l:str    r2, [r0]            /* clear loop... */
        add    r0, r0, #4
        cmp    r0, r1
        bne    clbss_l
    
    #ifdef CONFIG_MMU_ENABLE
        bl    mmu_turn_on
    #endif
    
        ldr    sp, =(CONFIG_SYS_INIT_SP_ADDR)
        bic    sp, sp, #7                    /* 8-byte alignment for ABI compliance */
        sub    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 */
        mov    r0, #0
        bl    board_init_f
    
        mov    sp, r9                        /* SP is GD's base address */
        bic    sp, sp, #7                    /* 8-byte alignment for ABI compliance */
        sub    sp, #GENERATED_BD_INFO_SIZE    /* allocate one BD above SP */
        bic    sp, sp, #7                    /* 8-byte alignment for ABI compliance */
    
        mov    r0, r9                        /* gd_t *gd */
        ldr r1, TEXT_BASE                /* ulong text */
        mov r2, sp                        /* ulong sp */
        bl    gdt_reset
    
        /* call board_init_r(gd_t *id, ulong dest_addr) */
        mov    r0, r9                            /* gd_t */
        ldr    r1,  =(CONFIG_SYS_MALLOC_END)    /* dest_addr for malloc heap end */
        /* call board_init_r */
        ldr    pc, =board_init_r                /* this is auto-relocated! */
    
    #else    /* CONFIG_RELOC_TO_TEXT_BASE */
    
        bl    _main
    #endif
    
    /*------------------------------------------------------------------------------*/
    
    ENTRY(c_runtime_cpu_setup)
    /*
     * If I-cache is enabled invalidate it
     */
    #ifndef CONFIG_SYS_ICACHE_OFF
        mcr    p15, 0, r0, c7, c5, 0    @ invalidate icache
        mcr     p15, 0, r0, c7, c10, 4    @ DSB
        mcr     p15, 0, r0, c7, c5, 4    @ ISB
    #endif
    /*
     * Move vector table
     */
        /* Set vector address in CP15 VBAR register */
        ldr     r0, =_stext
        mcr     p15, 0, r0, c12, c0, 0  @Set VBAR
    
        bx    lr
    
    ENDPROC(c_runtime_cpu_setup)
    
    /*************************************************************************
     *
     * void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
     *    __attribute__((weak));
     *
     * Stack pointer is not yet initialized at this moment
     * Don't save anything to stack even if compiled with -O0
     *
     *************************************************************************/
    ENTRY(save_boot_params)
        bx    lr            @ back to my caller
    ENDPROC(save_boot_params)
        .weak    save_boot_params
    
    /*************************************************************************
     *
     * cpu_init_cp15
     *
     * Setup CP15 registers (cache, MMU, TLBs). The I-cache is turned on unless
     * CONFIG_SYS_ICACHE_OFF is defined.
     * 操作CP15协处理器
     *
     *************************************************************************/
    ENTRY(cpu_init_cp15)
        /*
         * Invalidate L1 I/D
         */
        mov    r0, #0            @ set up for MCR
        mcr    p15, 0, r0, c8, c7, 0    @ invalidate TLBs
        mcr    p15, 0, r0, c7, c5, 0    @ invalidate icache
        mcr    p15, 0, r0, c7, c5, 6    @ invalidate BP array
    
        dsb
        isb
    
        /*
         * disable MMU stuff and caches
         *下面主要是中断相关代码,但是U-boot基本不使用中断所以暂且略过。
         */
        mrc    p15, 0, r0, c1, c0, 0
        bic    r0, r0, #0x00002000    @ clear bits 13 (--V-)
        bic    r0, r0, #0x00000007    @ clear bits 2:0 (-CAM)
        orr    r0, r0, #0x00000002    @ set bit 1 (--A-) Align
        orr    r0, r0, #0x00000800    @ set bit 11 (Z---) BTB
    #ifdef CONFIG_SYS_ICACHE_OFF
        bic    r0, r0, #0x00001000    @ clear bit 12 (I) I-cache
    #else
        orr    r0, r0, #0x00001000    @ set bit 12 (I) I-cache
    #endif
        mcr    p15, 0, r0, c1, c0, 0
        mov    pc, lr            @ back to my caller
    ENDPROC(cpu_init_cp15)
    
    #ifndef CONFIG_SKIP_LOWLEVEL_INIT
    /*************************************************************************
     *
     * CPU_init_critical registers
     *
     * setup important registers
     * setup memory timing
     *
     *************************************************************************/
    ENTRY(cpu_init_crit)
        /*
         * Jump to board specific initialization...
         * The Mask ROM will have already initialized
         * basic memory. Go here to bump up clock rate and handle
         * wake up conditions.
         */
    /* 
    
    调用board/lowlevel_init.S中的lowlevel_init函数,对系统总线的初始化,初始化了连接存储器的位宽、速度、刷新率等重要参数。经过这个函数的正确初始化,Nor Flash、SDRAM才可以被系统使用。
     */
        b    lowlevel_init        @ go setup pll,mux,memory
    ENDPROC(cpu_init_crit)
    #endif

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    3◑现在我们再来看看lib/arm/board.c中的第二阶段入口函数board_init_r:

    /*
     * (C) Copyright 2002-2006
     * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
     *
     * (C) Copyright 2002
     * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
     * Marius Groeger <mgroeger@sysgo.de>
     *
     * SPDX-License-Identifier:    GPL-2.0+
     */
    
    /*
     * To match the U-Boot user interface on ARM platforms to the U-Boot
     * standard (as on PPC platforms), some messages with debug character
     * are removed from the default U-Boot build.
     *
     * Define DEBUG here if you want additional info as shown below
     * printed upon startup:
     *
     * U-Boot code: 00F00000 -> 00F3C774  BSS: -> 00FC3274
     * IRQ Stack: 00ebff7c
     * FIQ Stack: 00ebef7c
     */
    
    #include <common.h>
    #include <command.h>
    #include <environment.h>
    #include <malloc.h>
    #include <stdio_dev.h>
    #include <version.h>
    #include <net.h>
    #include <serial.h>
    #include <nand.h>
    #include <onenand_uboot.h>
    #include <mmc.h>
    #include <scsi.h>
    #include <libfdt.h>
    #include <fdtdec.h>
    #include <post.h>
    #include <logbuff.h>
    #include <asm/sections.h>
    
    #ifdef CONFIG_BITBANGMII
    #include <miiphy.h>
    #endif
    
    DECLARE_GLOBAL_DATA_PTR;
    
    ulong monitor_flash_len;
    
    #ifdef CONFIG_HAS_DATAFLASH
    extern int  AT91F_DataflashInit(void);
    extern void dataflash_print_info(void);
    #endif
    
    #if defined(CONFIG_HARD_I2C) || 
        defined(CONFIG_SYS_I2C)
    #include <i2c.h>
    #endif
    
    /************************************************************************
     * Coloured LED functionality
     ************************************************************************
     * May be supplied by boards if desired
     */
    inline void __coloured_LED_init(void) {}
    void coloured_LED_init(void)
        __attribute__((weak, alias("__coloured_LED_init")));
    inline void __red_led_on(void) {}
    void red_led_on(void) __attribute__((weak, alias("__red_led_on")));
    inline void __red_led_off(void) {}
    void red_led_off(void) __attribute__((weak, alias("__red_led_off")));
    inline void __green_led_on(void) {}
    void green_led_on(void) __attribute__((weak, alias("__green_led_on")));
    inline void __green_led_off(void) {}
    void green_led_off(void) __attribute__((weak, alias("__green_led_off")));
    inline void __yellow_led_on(void) {}
    void yellow_led_on(void) __attribute__((weak, alias("__yellow_led_on")));
    inline void __yellow_led_off(void) {}
    void yellow_led_off(void) __attribute__((weak, alias("__yellow_led_off")));
    inline void __blue_led_on(void) {}
    void blue_led_on(void) __attribute__((weak, alias("__blue_led_on")));
    inline void __blue_led_off(void) {}
    void blue_led_off(void) __attribute__((weak, alias("__blue_led_off")));
    
    /*
     ************************************************************************
     * Init Utilities                            *
     ************************************************************************
     * Some of this code should be moved into the core functions,
     * or dropped completely,
     * but let's get it working (again) first...
     */
    
    #if defined(CONFIG_ARM_DCC) && !defined(CONFIG_BAUDRATE)
    #define CONFIG_BAUDRATE 115200
    #endif
    
    static int init_baudrate(void)
    {
        gd->baudrate = getenv_ulong("baudrate", 10, CONFIG_BAUDRATE);
        return 0;
    }
    
    static int display_banner(void)
    {
        printf("
    
    %s
    
    ", version_string);
        debug("U-Boot code: %08lX -> %08lX  BSS: -> %08lX
    ",
               (ulong)&_start,
               (ulong)&__bss_start, (ulong)&__bss_end);
    #ifdef CONFIG_MODEM_SUPPORT
        debug("Modem Support enabled
    ");
    #endif
    #ifdef CONFIG_USE_IRQ
        debug("IRQ Stack: %08lx
    ", IRQ_STACK_START);
        debug("FIQ Stack: %08lx
    ", FIQ_STACK_START);
    #endif
    
        return (0);
    }
    
    /*
     * WARNING: this code looks "cleaner" than the PowerPC version, but
     * has the disadvantage that you either get nothing, or everything.
     * On PowerPC, you might see "DRAM: " before the system hangs - which
     * gives a simple yet clear indication which part of the
     * initialization if failing.
     */
    static int display_dram_config(void)
    {
        int i;
    
    #ifdef DEBUG
        puts("RAM Configuration:
    ");
    
        for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
            printf("Bank #%d: %08lx ", i, gd->bd->bi_dram[i].start);
            print_size(gd->bd->bi_dram[i].size, "
    ");
        }
    #else
        ulong size = 0;
    
        for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++)
            size += gd->bd->bi_dram[i].size;
    
        puts("DRAM:  ");
        print_size(size, "
    ");
    #endif
    
        return (0);
    }
    
    #if defined(CONFIG_HARD_I2C) || defined(CONFIG_SYS_I2C)
    static int init_func_i2c(void)
    {
        puts("I2C:   ");
    #ifdef CONFIG_SYS_I2C
        i2c_init_all();
    #else
        i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
    #endif
        puts("ready
    ");
        return (0);
    }
    #endif
    
    #if defined(CONFIG_CMD_PCI) || defined (CONFIG_PCI)
    #include <pci.h>
    static int arm_pci_init(void)
    {
        pci_init();
        return 0;
    }
    #endif /* CONFIG_CMD_PCI || CONFIG_PCI */
    
    /*
     * Breathe some life into the board...
     *
     * Initialize a serial port as console, and carry out some hardware
     * tests.
     *
     * The first part of initialization is running from Flash memory;
     * its main purpose is to initialize the RAM so that we
     * can relocate the monitor code to RAM.
     */
    
    /*
     * All attempts to come up with a "common" initialization sequence
     * that works for all boards and architectures failed: some of the
     * requirements are just _too_ different. To get rid of the resulting
     * mess of board dependent #ifdef'ed code we now make the whole
     * initialization sequence configurable to the user.
     *
     * The requirements for any new initalization function is simple: it
     * receives a pointer to the "global data" structure as it's only
     * argument, and returns an integer return code, where 0 means
     * "continue" and != 0 means "fatal error, hang the system".
     */
    typedef int (init_fnc_t) (void);
    
    void __dram_init_banksize(void)
    {
        gd->bd->bi_dram[0].start = CONFIG_SYS_SDRAM_BASE;
        gd->bd->bi_dram[0].size =  gd->ram_size;
    }
    void dram_init_banksize(void)
        __attribute__((weak, alias("__dram_init_banksize")));
    
    int __arch_cpu_init(void)
    {
        return 0;
    }
    int arch_cpu_init(void)
        __attribute__((weak, alias("__arch_cpu_init")));
    
    int __power_init_board(void)
    {
        return 0;
    }
    int power_init_board(void)
        __attribute__((weak, alias("__power_init_board")));
    
        /* Record the board_init_f() bootstage (after arch_cpu_init()) */
    static int mark_bootstage(void)
    {
        bootstage_mark_name(BOOTSTAGE_ID_START_UBOOT_F, "board_init_f");
    
        return 0;
    }
    
    init_fnc_t *init_sequence[] = {
        arch_cpu_init,        /* basic arch cpu dependent setup */
        mark_bootstage,
    #ifdef CONFIG_OF_CONTROL
        fdtdec_check_fdt,
    #endif
    #if defined(CONFIG_BOARD_EARLY_INIT_F)
        board_early_init_f,
    #endif
        timer_init,        /* initialize timer */
    #ifdef CONFIG_BOARD_POSTCLK_INIT
        board_postclk_init,
    #endif
    #ifdef CONFIG_FSL_ESDHC
        get_clocks,
    #endif
        env_init,        /* initialize environment */
        init_baudrate,        /* initialze baudrate settings */
        serial_init,        /* serial communications setup */
        console_init_f,        /* stage 1 init of console */
        display_banner,        /* say that we are here */
        print_cpuinfo,        /* display cpu info (and speed) */
    #if defined(CONFIG_DISPLAY_BOARDINFO)
        checkboard,        /* display board info */
    #endif
    #if defined(CONFIG_HARD_I2C) || defined(CONFIG_SYS_I2C)
        init_func_i2c,
    #endif
        dram_init,        /* configure available RAM banks */
        NULL,
    };
    
    void board_init_f(ulong bootflag)
    {
        bd_t *bd;
        init_fnc_t **init_fnc_ptr;
        gd_t *id;
        ulong addr, addr_sp;
    #ifdef CONFIG_PRAM
        ulong reg;
    #endif
        void *new_fdt = NULL;
        size_t fdt_size = 0;
    
        memset((void *)gd, 0, sizeof(gd_t));
    
        gd->mon_len = (ulong)&__bss_end - (ulong)_start;
    #ifdef CONFIG_OF_EMBED
        /* Get a pointer to the FDT */
        gd->fdt_blob = __dtb_dt_begin;
    #elif defined CONFIG_OF_SEPARATE
        /* FDT is at end of image */
        gd->fdt_blob = &_end;
    #endif
        /* Allow the early environment to override the fdt address */
        gd->fdt_blob = (void *)getenv_ulong("fdtcontroladdr", 16,
                            (uintptr_t)gd->fdt_blob);
    
        for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
            if ((*init_fnc_ptr)() != 0) {
                hang ();
            }
        }
    
    #ifdef CONFIG_OF_CONTROL
        /* For now, put this check after the console is ready */
        if (fdtdec_prepare_fdt()) {
            panic("** CONFIG_OF_CONTROL defined but no FDT - please see "
                "doc/README.fdt-control");
        }
    #endif
    
        debug("monitor len: %08lX
    ", gd->mon_len);
        /*
         * Ram is setup, size stored in gd !!
         */
        debug("ramsize: %08lX
    ", gd->ram_size);
    #if defined(CONFIG_SYS_MEM_TOP_HIDE)
        /*
         * Subtract specified amount of memory to hide so that it won't
         * get "touched" at all by U-Boot. By fixing up gd->ram_size
         * the Linux kernel should now get passed the now "corrected"
         * memory size and won't touch it either. This should work
         * for arch/ppc and arch/powerpc. Only Linux board ports in
         * arch/powerpc with bootwrapper support, that recalculate the
         * memory size from the SDRAM controller setup will have to
         * get fixed.
         */
        gd->ram_size -= CONFIG_SYS_MEM_TOP_HIDE;
    #endif
    
        addr = CONFIG_SYS_SDRAM_BASE + get_effective_memsize();
    
    #ifdef CONFIG_LOGBUFFER
    #ifndef CONFIG_ALT_LB_ADDR
        /* reserve kernel log buffer */
        addr -= (LOGBUFF_RESERVE);
        debug("Reserving %dk for kernel logbuffer at %08lx
    ", LOGBUFF_LEN,
            addr);
    #endif
    #endif
    
    #ifdef CONFIG_PRAM
        /*
         * reserve protected RAM
         */
        reg = getenv_ulong("pram", 10, CONFIG_PRAM);
        addr -= (reg << 10);        /* size is in kB */
        debug("Reserving %ldk for protected RAM at %08lx
    ", reg, addr);
    #endif /* CONFIG_PRAM */
    
    #if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
        /* reserve TLB table */
        gd->arch.tlb_size = PGTABLE_SIZE;
        addr -= gd->arch.tlb_size;
    
        /* round down to next 64 kB limit */
        addr &= ~(0x10000 - 1);
    
        gd->arch.tlb_addr = addr;
        debug("TLB table from %08lx to %08lx
    ", addr, addr + gd->arch.tlb_size);
    #endif
    
        /* round down to next 4 kB limit */
        addr &= ~(4096 - 1);
        debug("Top of RAM usable for U-Boot at: %08lx
    ", addr);
    
    #ifdef CONFIG_LCD
    #ifdef CONFIG_FB_ADDR
        gd->fb_base = CONFIG_FB_ADDR;
    #else
        /* reserve memory for LCD display (always full pages) */
        addr = lcd_setmem(addr);
        gd->fb_base = addr;
    #endif /* CONFIG_FB_ADDR */
    #endif /* CONFIG_LCD */
    
        /*
         * reserve memory for U-Boot code, data & bss
         * round down to next 4 kB limit
         */
        addr -= gd->mon_len;
        addr &= ~(4096 - 1);
    
        debug("Reserving %ldk for U-Boot at: %08lx
    ", gd->mon_len >> 10, addr);
    
    #ifndef CONFIG_SPL_BUILD
        /*
         * reserve memory for malloc() arena
         */
        addr_sp = addr - TOTAL_MALLOC_LEN;
        debug("Reserving %dk for malloc() at: %08lx
    ",
                TOTAL_MALLOC_LEN >> 10, addr_sp);
        /*
         * (permanently) allocate a Board Info struct
         * and a permanent copy of the "global" data
         */
        addr_sp -= sizeof (bd_t);
        bd = (bd_t *) addr_sp;
        gd->bd = bd;
        debug("Reserving %zu Bytes for Board Info at: %08lx
    ",
                sizeof (bd_t), addr_sp);
    
    #ifdef CONFIG_MACH_TYPE
        gd->bd->bi_arch_number = CONFIG_MACH_TYPE; /* board id for Linux */
    #endif
    
        addr_sp -= sizeof (gd_t);
        id = (gd_t *) addr_sp;
        debug("Reserving %zu Bytes for Global Data at: %08lx
    ",
                sizeof (gd_t), addr_sp);
    
    #if defined(CONFIG_OF_SEPARATE) && defined(CONFIG_OF_CONTROL)
        /*
         * If the device tree is sitting immediate above our image then we
         * must relocate it. If it is embedded in the data section, then it
         * will be relocated with other data.
         */
        if (gd->fdt_blob) {
            fdt_size = ALIGN(fdt_totalsize(gd->fdt_blob) + 0x1000, 32);
    
            addr_sp -= fdt_size;
            new_fdt = (void *)addr_sp;
            debug("Reserving %zu Bytes for FDT at: %08lx
    ",
                  fdt_size, addr_sp);
        }
    #endif
    
    #ifndef CONFIG_ARM64
        /* setup stackpointer for exeptions */
        gd->irq_sp = addr_sp;
    #ifdef CONFIG_USE_IRQ
        addr_sp -= (CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ);
        debug("Reserving %zu Bytes for IRQ stack at: %08lx
    ",
            CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ, addr_sp);
    #endif
        /* leave 3 words for abort-stack    */
        addr_sp -= 12;
    
        /* 8-byte alignment for ABI compliance */
        addr_sp &= ~0x07;
    #else    /* CONFIG_ARM64 */
        /* 16-byte alignment for ABI compliance */
        addr_sp &= ~0x0f;
    #endif    /* CONFIG_ARM64 */
    #else
        addr_sp += 128;    /* leave 32 words for abort-stack   */
        gd->irq_sp = addr_sp;
    #endif
    
        debug("New Stack Pointer is: %08lx
    ", addr_sp);
    
    #ifdef CONFIG_POST
        post_bootmode_init();
        post_run(NULL, POST_ROM | post_bootmode_get(0));
    #endif
    
        /* Ram ist board specific, so move it to board code ... */
        dram_init_banksize();
        display_dram_config();    /* and display it */
    
        gd->relocaddr = addr;
        gd->start_addr_sp = addr_sp;
        gd->reloc_off = addr - (ulong)&_start;
        debug("relocation Offset is: %08lx
    ", gd->reloc_off);
        if (new_fdt) {
            memcpy(new_fdt, gd->fdt_blob, fdt_size);
            gd->fdt_blob = new_fdt;
        }
        memcpy(id, (void *)gd, sizeof(gd_t));
    }
    
    #if !defined(CONFIG_SYS_NO_FLASH)
    static char *failed = "*** failed ***
    ";
    #endif
    
    /*
     * Tell if it's OK to load the environment early in boot.
     *
     * If CONFIG_OF_CONFIG is defined, we'll check with the FDT to see
     * if this is OK (defaulting to saying it's not OK).
     *
     * NOTE: Loading the environment early can be a bad idea if security is
     *       important, since no verification is done on the environment.
     *
     * @return 0 if environment should not be loaded, !=0 if it is ok to load
     */
    static int should_load_env(void)
    {
    #ifdef CONFIG_OF_CONTROL
        return fdtdec_get_config_int(gd->fdt_blob, "load-environment", 1);
    #elif defined CONFIG_DELAY_ENVIRONMENT
        return 0;
    #else
        return 1;
    #endif
    }
    
    #if defined(CONFIG_DISPLAY_BOARDINFO_LATE) && defined(CONFIG_OF_CONTROL)
    static void display_fdt_model(const void *blob)
    {
        const char *model;
    
        model = (char *)fdt_getprop(blob, 0, "model", NULL);
        printf("Model: %s
    ", model ? model : "<unknown>");
    }
    #endif
    
    /************************************************************************
     *
     * This is the next part if the initialization sequence: we are now
     * running from RAM and have a "normal" C environment, i. e. global
     * data can be written, BSS has been cleared, the stack size in not
     * that critical any more, etc.
     *
     ************************************************************************
     */
    
    void board_init_r(gd_t *id, ulong dest_addr)
    {
        ulong malloc_start;
    #if !defined(CONFIG_SYS_NO_FLASH)
        ulong flash_size;
    #endif
    
        gd->flags |= GD_FLG_RELOC;    /* tell others: relocation done */
        bootstage_mark_name(BOOTSTAGE_ID_START_UBOOT_R, "board_init_r");
    
        monitor_flash_len = (ulong)&__rel_dyn_end - (ulong)_start;
    
        /* Enable caches */
        enable_caches();
    
        debug("monitor flash len: %08lX
    ", monitor_flash_len);
        board_init();    /* Setup chipselects */
        /*
         * TODO: printing of the clock inforamtion of the board is now
         * implemented as part of bdinfo command. Currently only support for
         * davinci SOC's is added. Remove this check once all the board
         * implement this.
         */
    #ifdef CONFIG_CLOCKS
        set_cpu_clk_info(); /* Setup clock information */
    #endif
        serial_initialize();
    
        debug("Now running in RAM - U-Boot at: %08lx
    ", dest_addr);
    
    #ifdef CONFIG_LOGBUFFER
        logbuff_init_ptrs();
    #endif
    #ifdef CONFIG_POST
        post_output_backlog();
    #endif
    
        /* The Malloc area is immediately below the monitor copy in DRAM */
        malloc_start = dest_addr - TOTAL_MALLOC_LEN;
        mem_malloc_init (malloc_start, TOTAL_MALLOC_LEN);
    
    #ifdef CONFIG_ARCH_EARLY_INIT_R
        arch_early_init_r();
    #endif
    
    #ifndef CONFIG_PMIC_REG_DUMP
        power_init_board();
    #endif
    
    #if !defined(CONFIG_SYS_NO_FLASH)
        puts("Flash: ");
    
        flash_size = flash_init();
        if (flash_size > 0) {
    # ifdef CONFIG_SYS_FLASH_CHECKSUM
            print_size(flash_size, "");
            /*
             * Compute and print flash CRC if flashchecksum is set to 'y'
             *
             * NOTE: Maybe we should add some WATCHDOG_RESET()? XXX
             */
            if (getenv_yesno("flashchecksum") == 1) {
                printf("  CRC: %08X", crc32(0,
                    (const unsigned char *) CONFIG_SYS_FLASH_BASE,
                    flash_size));
            }
            putc('
    ');
    # else    /* !CONFIG_SYS_FLASH_CHECKSUM */
            print_size(flash_size, "
    ");
    # endif /* CONFIG_SYS_FLASH_CHECKSUM */
        } else {
            puts(failed);
            hang();
        }
    #endif
    
    #if defined(CONFIG_CMD_NAND)
    #if defined(CONFIG_NAND_MTD)
        puts("NAND:  ");
        nand_init();        /* go init the NAND */
    #elif defined(CONFIG_NAND_FTL)
    #include <nand_ftl.h>
        puts("NAND FTL:  ");
        nand_ftl_init();        /* go init the NAND */
    #endif
    #endif /* CONFIG_CMD_NAND */
    
    #if defined(CONFIG_CMD_ONENAND)
        onenand_init();
    #endif
    
    #ifdef CONFIG_GENERIC_MMC
        puts("MMC:   ");
        mmc_initialize(gd->bd);
    #endif
    
    #ifdef CONFIG_CMD_SCSI
        puts("SCSI:  ");
        scsi_init();
    #endif
    
    #ifdef CONFIG_HAS_DATAFLASH
        AT91F_DataflashInit();
        dataflash_print_info();
    #endif
    
        /* initialize environment */
        if (should_load_env())
            env_relocate();
        else
            set_default_env(NULL);
    
    #if defined(CONFIG_CMD_PCI) || defined(CONFIG_PCI)
        arm_pci_init();
    #endif
    
        stdio_init();    /* get the devices list going. */
    
        jumptable_init();
    
    #if defined(CONFIG_API)
        /* Initialize API */
        api_init();
    #endif
    
        console_init_r();    /* fully init console as a device */
    
    #ifdef CONFIG_PMIC_REG_DUMP
        power_init_board();
    #endif
    
    #ifdef CONFIG_DISPLAY_BOARDINFO_LATE
    # ifdef CONFIG_OF_CONTROL
        /* Put this here so it appears on the LCD, now it is ready */
        display_fdt_model(gd->fdt_blob);
    # else
        checkboard();
    # endif
    #endif
    
    #if defined(CONFIG_ARCH_MISC_INIT)
        /* miscellaneous arch dependent initialisations */
        arch_misc_init();
    #endif
    #if defined(CONFIG_MISC_INIT_R)
        /* miscellaneous platform dependent initialisations */
        misc_init_r();
    #endif
    
         /* set up exceptions */
        interrupt_init();
        /* enable exceptions */
        enable_interrupts();
    
        /* Initialize from environment */
        load_addr = getenv_ulong("loadaddr", 16, load_addr);
    
    #ifdef CONFIG_BOARD_LATE_INIT
        board_late_init();
    #endif
    
    #ifdef CONFIG_BITBANGMII
        bb_miiphy_init();
    #endif
    #if defined(CONFIG_CMD_NET)
        puts("Net:   ");
        eth_initialize(gd->bd);
    #if defined(CONFIG_RESET_PHY_R)
        debug("Reset Ethernet PHY
    ");
        reset_phy();
    #endif
    #endif
    
    #ifdef CONFIG_POST
        post_run(NULL, POST_RAM | post_bootmode_get(0));
    #endif
    
    #if defined(CONFIG_PRAM) || defined(CONFIG_LOGBUFFER)
        /*
         * Export available size of memory for Linux,
         * taking into account the protected RAM at top of memory
         */
        {
            ulong pram = 0;
            uchar memsz[32];
    
    #ifdef CONFIG_PRAM
            pram = getenv_ulong("pram", 10, CONFIG_PRAM);
    #endif
    #ifdef CONFIG_LOGBUFFER
    #ifndef CONFIG_ALT_LB_ADDR
            /* Also take the logbuffer into account (pram is in kB) */
            pram += (LOGBUFF_LEN + LOGBUFF_OVERHEAD) / 1024;
    #endif
    #endif
            sprintf((char *)memsz, "%ldk", (gd->ram_size / 1024) - pram);
            setenv("mem", (char *)memsz);
        }
    #endif
    
        /* main_loop() can return to retry autoboot, if so just run it again. */
        for (;;) {
            main_loop();
        }
        /*
        进入主循环,其中会读取bootdelay和bootcmd
    
        在bootdelay时间内按下键进入命令行,否则执行bootcmd的命令。
        */
        /* NOTREACHED - no way out of command loop except booting */
    }

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  • 原文地址:https://www.cnblogs.com/Ph-one/p/4810900.html
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