arm9_uboot_分析源码

深藏阁楼爱情的钟 2023-06-01 06:20 35阅读 0赞

第一阶段：

1.硬件设备初始化：将CPU设为SVC模式，关闭开门狗，设置时钟，关闭MMU,Cache（在u-boot-1.1.6/cpu/arm920t/start.s中定义）

2.准备ram:设置存储控制器（在u-boot-1.1.6/board/100ask24x0/lowlevel.s中实现）

#include <config.h>
    #include <version.h>
    
    #define BWSCON    0x48000000
    
    /* BWSCON */
    #define DW8             (0x0)
    #define DW16             (0x1)
    #define DW32             (0x2)
    #define WAIT             (0x1<<2)
    #define UBLB             (0x1<<3)
    
    #define B1_BWSCON          (DW16)
    #define B2_BWSCON          (DW16)
    //#define B3_BWSCON          (DW16 + WAIT + UBLB)
    #define B3_BWSCON          (DW16 + UBLB)
    #define B4_BWSCON          (DW16 + WAIT + UBLB)
    #define B5_BWSCON          (DW8)
    #define B6_BWSCON          (DW32)
    #define B7_BWSCON          (DW32)
    
    /* BANK0CON */
    #define B0_Tacs             0x0    /*  0clk */
    #define B0_Tcos             0x0    /*  0clk */
    #define B0_Tacc             0x7    /* 14clk */
    #define B0_Tcoh             0x0    /*  0clk */
    #define B0_Tah             0x0    /*  0clk */
    #define B0_Tacp             0x0
    #define B0_PMC             0x0    /* normal */
    
    /* BANK1CON */
    #define B1_Tacs             0x0    /*  0clk */
    #define B1_Tcos             0x0    /*  0clk */
    #define B1_Tacc             0x7    /* 14clk */
    #define B1_Tcoh             0x0    /*  0clk */
    #define B1_Tah             0x0    /*  0clk */
    #define B1_Tacp             0x0
    #define B1_PMC             0x0
    
    #define B2_Tacs             0x0
    #define B2_Tcos             0x0
    #define B2_Tacc             0x7
    #define B2_Tcoh             0x0
    #define B2_Tah             0x0
    #define B2_Tacp             0x0
    #define B2_PMC             0x0
    
    #define B3_Tacs             0x0    /*  0clk */
    #define B3_Tcos             0x3    /*  4clk */
    #define B3_Tacc             0x7    /* 14clk */
    #define B3_Tcoh             0x1    /*  1clk */
    #define B3_Tah             0x0    /*  0clk */
    #define B3_Tacp             0x3     /*  6clk */
    #define B3_PMC             0x0    /* normal */
    
    #define B4_Tacs             0x0    /*  0clk */
    #define B4_Tcos             0x3    /*  4clk */
    #define B4_Tacc             0x7    /* 14clk */
    #define B4_Tcoh             0x1    /*  1clk */
    #define B4_Tah             0x3    /*  4clk */
    #define B4_Tacp             0x6 /*  6clk */
    #define B4_PMC             0x0    /* normal */
    
    #define B5_Tacs             0x0    /*  0clk */
    #define B5_Tcos             0x0    /*  0clk */
    #define B5_Tacc             0x7    /* 14clk */
    #define B5_Tcoh             0x0    /*  0clk */
    #define B5_Tah             0x0    /*  0clk */
    #define B5_Tacp             0x0
    #define B5_PMC             0x0    /* normal */
    
    #define B6_MT             0x3    /* SDRAM */
    #define B6_Trcd              0x1
    #define B6_SCAN             0x1    /* 9bit */
    
    #define B7_MT             0x3    /* SDRAM */
    #define B7_Trcd             0x1    /* 3clk */
    #define B7_SCAN             0x1    /* 9bit */
    
    /* REFRESH parameter */
    #define REFEN             0x1    /* Refresh enable */
    #define TREFMD             0x0    /* CBR(CAS before RAS)/Auto refresh */
    #define Trp                 0x0    /* 2clk */
    #define Trc                0x3    /* 7clk */
    #define Tchr             0x2    /* 3clk */
    #define REFCNT             0x4f4    /* period=7.8125us, HCLK=100Mhz, (2048+1-7.8125*100) */
    /**************************************/
    
    _TEXT_BASE:
        .word    TEXT_BASE
    
    .globl lowlevel_init
    lowlevel_init:
        ldr     r0, =SMRDATA  /* 使r0相对于当前位置，以便它从闪存而不是内存中读取SMRDATA*/
        ldr    r1, _TEXT_BASE
        sub    r0, r0, r1
        ldr    r1, =BWSCON    /* Bus Width Status Controller */
        add     r2, r0, #13*4
    0:
        ldr     r3, [r0], #4
        str     r3, [r1], #4
        cmp     r2, r0
        bne     0b
    
        /* everything is fine now */
        mov    pc, lr
    
        .ltorg
    /* the literal pools origin */
    
    SMRDATA:
        .word (0+(B1_BWSCON<<4)+(B2_BWSCON<<8)+(B3_BWSCON<<12)+(B4_BWSCON<<16)+(B5_BWSCON<<20)+(B6_BWSCON<<24)+(B7_BWSCON<<28)) 
        .word ((B0_Tacs<<13)+(B0_Tcos<<11)+(B0_Tacc<<8)+(B0_Tcoh<<6)+(B0_Tah<<4)+(B0_Tacp<<2)+(B0_PMC))
        .word ((B1_Tacs<<13)+(B1_Tcos<<11)+(B1_Tacc<<8)+(B1_Tcoh<<6)+(B1_Tah<<4)+(B1_Tacp<<2)+(B1_PMC))
        .word ((B2_Tacs<<13)+(B2_Tcos<<11)+(B2_Tacc<<8)+(B2_Tcoh<<6)+(B2_Tah<<4)+(B2_Tacp<<2)+(B2_PMC))
        .word ((B3_Tacs<<13)+(B3_Tcos<<11)+(B3_Tacc<<8)+(B3_Tcoh<<6)+(B3_Tah<<4)+(B3_Tacp<<2)+(B3_PMC))
        .word ((B4_Tacs<<13)+(B4_Tcos<<11)+(B4_Tacc<<8)+(B4_Tcoh<<6)+(B4_Tah<<4)+(B4_Tacp<<2)+(B4_PMC))
        .word ((B5_Tacs<<13)+(B5_Tcos<<11)+(B5_Tacc<<8)+(B5_Tcoh<<6)+(B5_Tah<<4)+(B5_Tacp<<2)+(B5_PMC))
        .word ((B6_MT<<15)+(B6_Trcd<<2)+(B6_SCAN))
        .word ((B7_MT<<15)+(B7_Trcd<<2)+(B7_SCAN))
        .word ((REFEN<<23)+(TREFMD<<22)+(Trp<<20)+(Trc<<18)+(Tchr<<16)+REFCNT)
        .word 0xb1
        .word 0x30
        .word 0x30

3.复制boot的第二阶段的代码到ram

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 clear\_bss  
  
ldr r2, \_armboot\_start  
ldr r3, \_bss\_start  
sub r2, r3, r2 /\* r2 <- size of armboot \*/  
\#if 1  
bl CopyCode2Ram /\* r0: source, r1: dest, r2: size \*/  
\#else  
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

4.设置好栈

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    */

5.跳转到第二阶段的C入口:先清理bss段，再调用arm\_lib/board.c的start\_armboot函数进入第二阶段

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

ldr    pc, _start_armboot
    
    _start_armboot:    .word start_armboot

void start_armboot (void)
    {
        init_fnc_t **init_fnc_ptr;
        char *s;
    #ifndef CFG_NO_FLASH
        ulong size;
    #endif
    #if defined(CONFIG_VFD) || defined(CONFIG_LCD)
        unsigned long addr;
    #endif
    
        /* Pointer is writable since we allocated a register for it */
        gd = (gd_t*)(_armboot_start - CFG_MALLOC_LEN - sizeof(gd_t));
        /* compiler optimization barrier needed for GCC >= 3.4 */
        __asm__ __volatile__("": : :"memory");
    
        memset ((void*)gd, 0, sizeof (gd_t));
        gd->bd = (bd_t*)((char*)gd - sizeof(bd_t));
        memset (gd->bd, 0, sizeof (bd_t));
    
        monitor_flash_len = _bss_start - _armboot_start;
    
        for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
            if ((*init_fnc_ptr)() != 0) {
                hang ();
            }
        }
    
    #ifndef CFG_NO_FLASH
        /* configure available FLASH banks */
        size = flash_init ();
        display_flash_config (size);
    #endif /* CFG_NO_FLASH */
    
    #ifdef CONFIG_VFD
    #    ifndef PAGE_SIZE
    #      define PAGE_SIZE 4096
    #    endif
        /*
         * reserve memory for VFD display (always full pages)
         */
        /* bss_end is defined in the board-specific linker script */
        addr = (_bss_end + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
        size = vfd_setmem (addr);
        gd->fb_base = addr;
    #endif /* CONFIG_VFD */
    
    #ifdef CONFIG_LCD
    #    ifndef PAGE_SIZE
    #      define PAGE_SIZE 4096
    #    endif
        /*
         * reserve memory for LCD display (always full pages)
         */
        /* bss_end is defined in the board-specific linker script */
        addr = (_bss_end + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
        size = lcd_setmem (addr);
        gd->fb_base = addr;
    #endif /* CONFIG_LCD */
    
        /* armboot_start is defined in the board-specific linker script */
        mem_malloc_init (_armboot_start - CFG_MALLOC_LEN);
    
    #if (CONFIG_COMMANDS & CFG_CMD_NAND)
        puts ("NAND:  ");
        nand_init();        /* go init the NAND */
    #endif
    
    #ifdef CONFIG_HAS_DATAFLASH
        AT91F_DataflashInit();
        dataflash_print_info();
    #endif
    
        /* initialize environment */
        env_relocate ();
    
    #ifdef CONFIG_VFD
        /* must do this after the framebuffer is allocated */
        drv_vfd_init();
    #endif /* CONFIG_VFD */
    
        /* IP Address */
        gd->bd->bi_ip_addr = getenv_IPaddr ("ipaddr");
    
        /* MAC Address */
        {
            int i;
            ulong reg;
            char *s, *e;
            char tmp[64];
    
            i = getenv_r ("ethaddr", tmp, sizeof (tmp));
            s = (i > 0) ? tmp : NULL;
    
            for (reg = 0; reg < 6; ++reg) {
                gd->bd->bi_enetaddr[reg] = s ? simple_strtoul (s, &e, 16) : 0;
                if (s)
                    s = (*e) ? e + 1 : e;
            }
    
    #ifdef CONFIG_HAS_ETH1
            i = getenv_r ("eth1addr", tmp, sizeof (tmp));
            s = (i > 0) ? tmp : NULL;
    
            for (reg = 0; reg < 6; ++reg) {
                gd->bd->bi_enet1addr[reg] = s ? simple_strtoul (s, &e, 16) : 0;
                if (s)
                    s = (*e) ? e + 1 : e;
            }
    #endif
        }
    
        devices_init ();    /* get the devices list going. */
    
    #ifdef CONFIG_CMC_PU2
        load_sernum_ethaddr ();
    #endif /* CONFIG_CMC_PU2 */
    
        jumptable_init ();
    
        console_init_r ();    /* fully init console as a device */
    
    #if defined(CONFIG_MISC_INIT_R)
        /* miscellaneous platform dependent initialisations */
        misc_init_r ();
    #endif
    
        Port_Init();
        if (!PreLoadedONRAM) {
            /* enable exceptions */
            enable_interrupts ();
            /* add by www.100ask.net */
            usb_init();
        }
    
        /* Perform network card initialisation if necessary */
    #ifdef CONFIG_DRIVER_CS8900
        cs8900_get_enetaddr (gd->bd->bi_enetaddr);
    #endif
    
    #if defined(CONFIG_DRIVER_SMC91111) || defined (CONFIG_DRIVER_LAN91C96)
        if (getenv ("ethaddr")) {
            smc_set_mac_addr(gd->bd->bi_enetaddr);
        }
    #endif /* CONFIG_DRIVER_SMC91111 || CONFIG_DRIVER_LAN91C96 */
    
        /* Initialize from environment */
        if ((s = getenv ("loadaddr")) != NULL) {
            load_addr = simple_strtoul (s, NULL, 16);
        }
    #if (CONFIG_COMMANDS & CFG_CMD_NET)
        if ((s = getenv ("bootfile")) != NULL) {
            copy_filename (BootFile, s, sizeof (BootFile));
        }
    #endif    /* CFG_CMD_NET */
    
    #ifdef BOARD_LATE_INIT
        board_late_init ();
    #endif
    #if (CONFIG_COMMANDS & CFG_CMD_NET)
    #if defined(CONFIG_NET_MULTI)
        puts ("Net:   ");
    #endif
        eth_initialize(gd->bd);
    #endif
        /* main_loop() can return to retry autoboot, if so just run it again. */
        for (;;) {
            main_loop ();
        }
    
        /* NOTREACHED - no way out of command loop except booting */
    }

第二阶段：

1.初始化本阶段用到的硬件：改变时钟，配置串口等

2.检测内存映射：板子的内存其实地址和大小

3.uboot命令的格式

4.为内核设置启动参数：对于arm架构，通过lib\_arm/armlinux.c的do\_bootm\_linux函数来启动内核，这个函数设置标记列表，最后通过

theKernel (0, bd->bi\_arch\_number, bd->bi\_boot\_params);调用内核

下图为uboot内存使用情况

![1424785-20190918210450200-1741277479.png][]

辨别是否从nor启动：

int bBootFrmNORFlash(void)
    {
        volatile unsigned int *pdw = (volatile unsigned int *)0;
        unsigned int dwVal;
        
        /*
         * 无论是从NOR Flash还是从NAND Flash启动，
         * 地址0处为指令"b    Reset", 机器码为0xEA00000B，
         * 对于从NAND Flash启动的情况，其开始4KB的代码会复制到CPU内部4K内存中，
         * 对于从NOR Flash启动的情况，NOR Flash的开始地址即为0。
         * 对于NOR Flash，必须通过一定的命令序列才能写数据，
         * 所以可以根据这点差别来分辨是从NAND Flash还是NOR Flash启动:
         * 向地址0写入一个数据，然后读出来，如果没有改变的话就是NOR Flash
         */
    
        dwVal = *pdw;       
        *pdw = 0x12345678;
        if (*pdw != 0x12345678)
        {
            return 1;
        }
        else
        {
            *pdw = dwVal;
            return 0;
        }
    }

转载于:https://www.cnblogs.com/lzd626/p/11545579.html

[1424785-20190918210450200-1741277479.png]: /images/20230601/cc4f98757ef14e41b2f817c93323d70b.png