DM365的UBL源码分析（转）

 

DM365是的启动方式有两种，通过BOOTSEL[2:0]引脚决定。当其为001时，直接从AEMIF上启动，比如NOR和OneNAND。除此之外皆是从RBL启动，顺序为RBL-UBL-UBOOT-KERNEL，比如NAND，串口，SD卡等。RBL会搜寻block1到block24去找UBL，关于RBL启动的详细细节可以参考用户指南关于ARM子系统的那篇文档，很详尽，下面只分析UBL的源码。

     UBL源码在PSP包里的board_utilities/flash_utils目录下，主要是COMMON目录和各子平台的目录如DM36x等，内中除了UBL的源码外还有CCS下JTAG的擦除烧写源码，串口烧写源码等。下面只分析UBL的启动代码。

     入门代码是汇编文件start.S，主要是切换操作模式，建立堆栈等，然后跳转到main函数，进入到board_utilities/flash_utils/Common/ubl/src目录下的C文件ubl.c中。main函数如下：

// Main entry point

void main(void)
{
   
    // Call to real boot function code

    LOCAL_boot();
   
    // Jump to entry point

    DEBUG_printString("/r/nJumping to entry point at ");
    DEBUG_printHexInt(gEntryPoint);
    DEBUG_printString("./r/n");
    APPEntry = (void (*)(void)) gEntryPoint;   
    (*APPEntry)();    
}

        U-boot一般存在于DEVICE_NAND_UBL_SEARCH_START_BLOCK以后块的第0页，ubl试着从DEVICE_NAND_UBL_SEARCH_START_BLOCK块向后搜索每块的第0页，找到后，前24个字节分别记录着u-boot描述，如入口函数等

//DM36x/CCS/NANDWriter/src/nandwriter.c   nandwriter()函数中

// Fill in NandBoot header，rxBuf为刚搜到的页
  gNandBoot.entryPoint = *(((Uint32 *)(&rxBuf[4])));
  gNandBoot.numPage = *(((Uint32 *)(&rxBuf[8])));
  gNandBoot.block = *(((Uint32 *)(&rxBuf[12])));
  gNandBoot.page = *(((Uint32 *)(&rxBuf[16])));
  gNandBoot.ldAddress = *(((Uint32 *)(&rxBuf[20])));

     根据以上信息一次读入每一页，然后将u-boot入口传递给gEntryPoint。

     main函数主要调用了LOCAL_boot函数来进行实质的引导功能，下面是此函数的内容：

static Uint32 LOCAL_boot(void)
{
    DEVICE_BootMode bootMode;
   
    // Read boot mode 从BOOTCFG系统寄存器读出，得到目前BOOTSEL[0..2]

    bootMode = DEVICE_bootMode();
   
    if (bootMode == DEVICE_BOOTMODE_UART)
    {
        // Wait until the RBL is done using the UART.
       //对于通过UART启动的，这些代码应该是存在于uart设备上
       while((UART0->LSR & 0x40) == 0 );
    }
   
    // Platform Initialization

    if ( DEVICE_init() != E_PASS )      
    {
        DEBUG_printString(devString);
        DEBUG_printString(" initialization failed!/r/n");
        asm(" MOV PC, #0");
    }
    else
    {
        DEBUG_printString(devString);
        DEBUG_printString(" initialization passed!/r/n");
    }
   
    // Set RAM pointer to beginning of RAM space

    UTIL_setCurrMemPtr(0);      
   
    // Send some information to host

    DEBUG_printString("TI UBL Version: ");
    DEBUG_printString(UBL_VERSION_STRING);
    DEBUG_printString("/r/nBooting Catalog Boot Loader/r/nBootMode = ");
   
    // Select Boot Mode

#if defined(UBL_NAND)
    {
        //Report Bootmode to host

        DEBUG_printString("NAND/r/n");
       
        // Copy binary image application from NAND to RAM
       //NANDBOOT_copy()首先打开NandFlash设备，将NandFlash的硬件信息放在hNandInfo数据结构内。移植ubl时需要修改与hNandInfo数据结构相关的参数，比如EMIF地址（EMIFStart  = 0x02000000 在ubl.cmd;) DEVICE_NAND_CHIP_infoTable结构中的页大小、块数、块中的页数、...
       if (NANDBOOT_copy() != E_PASS)     
        {
            DEBUG_printString("NAND Boot failed./r/n");
            LOCAL_bootAbort();
        }
    }
#elif defined(UBL_NOR)
    {
       //Report Bootmode to host

        DEBUG_printString("NOR /r/n");
       
        // Copy binary application image from NOR to RAM

        if (NORBOOT_copy() != E_PASS)
        {
            DEBUG_printString("NOR Boot failed./r/n");
            LOCAL_bootAbort();
        }
    }
#elif defined(UBL_SD_MMC)
    {
        //Report Bootmode to host

        DEBUG_printString("SD/MMC /r/n");
       
        // Copy binary of application image from SD/MMC card to RAM

        if (SDMMCBOOT_copy() != E_PASS)
        {
            DEBUG_printString("SD/MMC Boot failed./r/n");
            LOCAL_bootAbort();
        }
    }
#else
    {
        //Report Bootmode to host

        DEBUG_printString("UART/r/n");
        UARTBOOT_copy();
    }
   
   
#endif
   
    DEBUG_printString(" DONE");
   
    UTIL_waitLoop(10000);
   
    DEVICE_TIMER0Stop();   
   
    return E_PASS;
}

     先通过调用DEVICE_bootMode函数来判断启动方式（通过读取SYS寄存器实现），而后调用了DEVICE_init函数来进行平台的最底层初始化，包括电源域，时钟，DDR，EMIF，UART，I2C，TIMER等。

     而后通过UTIL_setCurrMemPtr函数对全局变量currMemPtr赋值，以后用到。接着通过判断不同的引导方式，采取不同的处理办法，以NAND启动为例，将调用NANDBOOT_copy函数。此函数将NAND中的某些内容（就是UBOOT）搬移到RAM中，而后UBL结束，控制权正式交给UBOOT。

看看UBL对平台的初始化，主要是调用了DEVICE_init函数，函数内容如下：

Uint32 DEVICE_init()
{
    Uint32 status = E_PASS;
   
    // Mask all interrupts
    AINTC->INTCTL = 0x4;
    AINTC->EABASE = 0x0;
    AINTC->EINT0 = 0x0;
    AINTC->EINT1 = 0x0;       
   
    // Clear all interrupts
    AINTC->FIQ0 = 0xFFFFFFFF;
    AINTC->FIQ1 = 0xFFFFFFFF;
    AINTC->IRQ0 = 0xFFFFFFFF;
    AINTC->IRQ1 = 0xFFFFFFFF;
   
#ifndef SKIP_LOW_LEVEL_INIT
   
    POR_RESET();
   
    // System PSC setup - enable all
    DEVICE_PSCInit();
   
   DEVICE_pinmuxControl(0,0xFFFFFFFF,0x00FD0000); // All Video Inputs，Y0-Y7全部作为video in（不作为GPIO），GIO43作为SD1的clk，McBsp开启，MMCSD0关闭

  DEVICE_pinmuxControl(1,0xFFFFFFFF,0x00145555); // All Video Outputs，视频Cout0-Cout7作为色度信号输出使能，场消隐/行消隐同步信号使能，LCD的OE功能关闭

  DEVICE_pinmuxControl(2,0xFFFFFFFF,0x000000DA); // EMIFA，总线使能，但是CE0没有使能，0xDA可能在合众达板子上运行有问题，因为他将ce0设置成GPIO，这样nandflash失效了，我想可能是TI原版有个cpld，在合众达的测试程序，值为0x55。

  DEVICE_pinmuxControl(3,0xFFFFFFFF,0x00180000); // SPI0, SPI1, UART1, I2C, SD0, SD1, McBSP0, CLKOUTs，串口1使能，其他均作为GPIO，网卡没使能

  DEVICE_pinmuxControl(4,0xFFFFFFFF,0x55555555); //SI1-SPI4使能，MMCSD1使能
   
   GPIO->DIR02 &= 0xfeffffff;
    GPIO->CLRDATA02 = 0x01000000;
   
    // System PLL setup
    if (status == E_PASS) status |= DEVICE_PLL1Init(PLL1_Mult);
   
    // DDR PLL setup
    if (status == E_PASS) status |= DEVICE_PLL2Init();
   
    // DDR2 module setup
    if (status == E_PASS) status |= DEVICE_DDR2Init();
#endif
   
    // AEMIF Setup
    if (status == E_PASS) status |= DEVICE_EMIFInit();
   
    // UART0 Setup
    if (status == E_PASS) status |= DEVICE_UART0Init();
   
    // TIMER0 Setup
    if (status == E_PASS) status |= DEVICE_TIMER0Init();
   
    // I2C0 Setup
    if (status == E_PASS) status |= DEVICE_I2C0Init();
   
    return status;
}

     首先屏蔽和清除中断，然后调用DEVICE_PSCInit函数实现对各模块的电源时钟使能，实质是调用PSC电源时钟管理模块的寄存器实现，函数内容如下：

void DEVICE_PSCInit()
{   
    unsigned char i=0;
    unsigned char lpsc_start;
    unsigned char lpsc_end,lpscgroup,lpscmin,lpscmax;
    unsigned int PdNum = 0;
   
    lpscmin =0;
    lpscmax =2;
   
    for(lpscgroup=lpscmin ; lpscgroup <=lpscmax; lpscgroup++) {
        if(lpscgroup==0)
        {
            lpsc_start = 0; // Enabling LPSC 3 to 28 SCR first

            lpsc_end = 28;
        }
        else if (lpscgroup == 1) {
            lpsc_start = 38;
            lpsc_end = 47;
        } else {
            lpsc_start = 50;
            lpsc_end = 51;
        }
       
        //NEXT=0x3, Enable LPSC's
        for(i=lpsc_start; i<=lpsc_end; i++) {
            PSC->MDCTL[i] |= 0x3;
        }
       
        //Program goctl to start transition sequence for LPSCs
        PSC->PTCMD = (1<<PdNum);
       
        //Wait for GOSTAT = NO TRANSITION from PSC for Pdomain 0
        while(! (((PSC->PTSTAT>> PdNum) & 0x00000001) == 0));
       
        //Wait for MODSTAT = ENABLE from LPSC's
        for(i=lpsc_start; i<=lpsc_end; i++) {
            while(!((PSC->MDSTAT[i] & 0x0000001F) == 0x3));            
        }   
    }    
   
}

     然后调用DEVICE_pinmuxControl函数决定复用引脚的功能选择，详见数据手册查看引脚功能。

     接着调用DM36x/common/src/device.c下的DEVICE_PLL1Init函数实现了PLL1的配置，预分频，倍频，后分频，分频到各个模块，其设置顺序可以参看用户指南ARM子系统文档，有详细的介绍，PLL2类似，函数内容如下：

Uint32 DEVICE_PLL1Init(Uint32 PLLMult)
{
    unsigned int CLKSRC=0x0;             
    unsigned int j;
   
  
    PLL1->PLLCTL &= 0xFFFFFFFD;       
   
    PLL1->PLLCTL &= 0xFFFFFEFF;            
    PLL1->PLLCTL |= CLKSRC<<8;
   
  
    PLL1->PLLCTL &= 0xFFFFFFDF;   
   
  
    PLL1->PLLCTL &= 0xFFFFFFFE;
   
    UTIL_waitLoop(150);                
   
    // PLLRST=1(reset assert)
    PLL1->PLLCTL |= 0x00000008;
   
    UTIL_waitLoop(300);
   
    
    PLL1->PLLCTL &= 0xFFFFFFF7;
   
    //Program the Multiper and Pre-Divider for PLL1
    PLL1->PLLM = 0x51; // VCO will 24*2M/N+1 = 486Mhz

    PLL1->PREDIV = 0x8000|0x7;
   
    PLL1->SECCTL = 0x00470000; // Assert TENABLE = 1, TENABLEDIV = 1, TINITZ = 1
    PLL1->SECCTL = 0x00460000; // Assert TENABLE = 1, TENABLEDIV = 1, TINITZ = 0
    PLL1->SECCTL = 0x00400000; // Assert TENABLE = 0, TENABLEDIV = 0, TINITZ = 0
    PLL1->SECCTL = 0x00410000; // Assert TENABLE = 0, TENABLEDIV = 0, TINITZ = 1   
 
    //Program the PostDiv for PLL1
    PLL1->POSTDIV = 0x8000;
   
    // Post divider setting for PLL1    
    PLL1->PLLDIV2 = 0x8001;
    PLL1->PLLDIV3 = 0x8001; // POST DIV 486/2 -> MJCP/HDVICP
    PLL1->PLLDIV4 = 0x8003; // POST DIV 486/4 -> EDMA/EDMA CFG
    PLL1->PLLDIV5 = 0x8001; // POST DIV 486/2 -> VPSS
    PLL1->PLLDIV6 = 0x8011; // 27Mhz POST DIV 486/18 -> VENC
    PLL1->PLLDIV7 = 0x8000; // POST DIV 486/2 -> DDR
    PLL1->PLLDIV8 = 0x8003; // POST DIV 486/4 -> MMC0/SD0
    PLL1->PLLDIV9 = 0x8001; // POST DIV 486/2 -> CLKOUT

    UTIL_waitLoop(300);
   
    
    PLL1->PLLCMD = 0x00000001; // Go

    UTIL_waitLoop(300);
       
  
    while(! (((SYSTEM->PLL0_CONFIG) & 0x07000000) == 0x07000000));   
   
  
    PLL1->PLLCTL |= 0x00000001; // PLLEN=0
 
    return E_PASS;
}

Uint32 DEVICE_PLL2Init()
{

...

// Post divider setting for PLL2
     PLL2->PLLDIV2 = 0x8001; // 594/2 =297 Mhz -> ARM
     PLL2->PLLDIV4 = 0x801C; // POST DIV 594/29 = 20.48 -> VOICE
     PLL2->PLLDIV5 = 0x8007;

...

}

     继续在DEVICE_init函数中，下面是调用DEVICE_DDR2Init函数来配置DDR控制器，这是UBL中重要的一部分，如果硬件电路需要更换内存芯片的话，需要在UBL中修改这个函数，即按照芯片手册来配置DDR控制寄存器中的相关参数，比如时序，BANK数，页大小等。这个函数主要是操作SYS模块和DDR模块的相关寄存器来配置内存，函数中调用的DEVICE_LPSCTransition函数用来实现模块的电源时钟状态的改变，函数内容如下：

Uint32 DEVICE_DDR2Init()
{
    DEVICE_LPSCTransition(LPSC_DDR2,0,PSC_ENABLE);
   
    SYSTEM->VTPIOCR = (SYSTEM->VTPIOCR)& 0xFFFF9F3F;
   
    // Set bit CLRZ (bit 13)
    SYSTEM->VTPIOCR = (SYSTEM->VTPIOCR) | 0x00002000;
   
    // Check VTP READY Status
    while( !(SYSTEM->VTPIOCR & 0x8000));
   
    // Set bit VTP_IOPWRDWN bit 14 for DDR input buffers)
    //SYSTEM->VTPIOCR = SYSTEM->VTPIOCR | 0x00004000;

    // Set bit LOCK(bit7) and PWRSAVE (bit8)
    SYSTEM->VTPIOCR = SYSTEM->VTPIOCR | 0x00000080;
   
    // Powerdown VTP as it is locked (bit 6)
    // Set bit VTP_IOPWRDWN bit 14 for DDR input buffers)
    SYSTEM->VTPIOCR = SYSTEM->VTPIOCR | 0x00004040;
   
    // Wait for calibration to complete
    UTIL_waitLoop( 150 );
   
    // Set the DDR2 to synreset, then enable it again
    DEVICE_LPSCTransition(LPSC_DDR2,0,PSC_SYNCRESET);
    DEVICE_LPSCTransition(LPSC_DDR2,0,PSC_ENABLE);
   
    DDR->DDRPHYCR = 0x000000C5;  
    DDR->SDBCR = 0x08D34832;        //Program SDRAM Bank Config Register
    DDR->SDBCR = 0x0853C832;   
    DDR->SDTIMR =0x3C934B51;        //Program SDRAM Timing Control Register1
    DDR->SDTIMR2 =0x4221C72;        //Program SDRAM Timing Control Register2
    DDR->PBBPR = 0x000000FE;  
    DDR->SDBCR = 0x08534832;        //Program SDRAM Bank Config Register  
    DDR->SDRCR = 0x00000768;        //Program SDRAM Refresh Control Register

    DEVICE_LPSCTransition(LPSC_DDR2,0,PSC_SYNCRESET);
    DEVICE_LPSCTransition(LPSC_DDR2,0,PSC_ENABLE);
   
    return E_PASS;
}

void DEVICE_LPSCTransition(Uint8 module, Uint8 domain, Uint8 state)
{
    // Wait for any outstanding transition to complete
    while ( (PSC->PTSTAT) & (0x00000001<< domain) );
   
    // If we are already in that state, just return
    if (((PSC->MDSTAT[module]) & 0x1F) == state) return;
   
    // Perform transition
    PSC->MDCTL[module] = ((PSC->MDCTL[module]) & (0xFFFFFFE0)) | (state);
    PSC->PTCMD |= (0x00000001<< domain);
   
    // Wait for transition to complete
    while ( (PSC->PTSTAT) & (0x00000001<< domain) );
   
    // Wait and verify the state
    while (((PSC->MDSTAT[module]) & 0x1F) != state);   
}

     而后调用DEVICE_EMIFInit函数来配置EMIF模块，这个模块用来接外存，比如NAND，NOR等。DM365有两个片选空间，如果某一空间配置成NAND，则需要在寄存器中设置，其函数内容如下：

Uint32 DEVICE_EMIFInit()
{   
    AEMIF->AWCCR = 0xff;  
    AEMIF->A1CR = 0x40400204; 
    AEMIF->NANDFCR |= 1; 
    AEMIF->A2CR = 0x00a00505;
   
    return E_PASS;  
}

     而后调用DEVICE_UART0Init函数来配置串口0，调用DEVICE_TIMER0Init函数来配置TIMER0，调用DEVICE_I2C0Init函数来配置I2C控制器，都是操作某一模块的控制寄存器实现，具体如何设置可以参考相关模块的手册，这三个函数的内容如下：

Uint32 DEVICE_UART0Init()
{   
    UART0->PWREMU_MGNT = 0; // Reset UART TX& RX components

    UTIL_waitLoop( 100 );
   
    UART0->MDR = 0x0;
    UART0->DLL = 0xd; // Set baud rate   
    UART0->DLH = 0;
    
    UART0->FCR = 0x0007; // Clear UART TX& RX FIFOs
    UART0->FCR = 0x0000; // Non-FIFO mode
    UART0->IER = 0x0007; // Enable interrupts

    UART0->LCR = 0x0003; // 8-bit words
    // 1 STOP bit generated,
    // No Parity, No Stick paritiy,
    // No Break control

    UART0->MCR = 0x0000; // RTS & CTS disabled,
    // Loopback mode disabled,
    // Autoflow disabled

    UART0->PWREMU_MGNT = 0xE001; // Enable TX& RX componenets

    return E_PASS;
}

Uint32 DEVICE_I2C0Init()
{
    I2C0->ICMDR = 0; // Reset I2C
    I2C0->ICPSC = 26; // Config prescaler for 27MHz
    I2C0->ICCLKL = 20; // Config clk LOW for 20kHz
    I2C0->ICCLKH = 20; // Config clk HIGH for 20kHz
    I2C0->ICMDR |= I2C_ICMDR_IRS; // Release I2C from reset
   
    return E_PASS;
}

Uint32 DEVICE_TIMER0Init()
{
    // Put timer into reset
    TIMER0->EMUMGT_CLKSPD = 0x00000003;
    TIMER0->TCR = 0x00000000;
   
    // Enable TINT0, TINT1 interrupt
    TIMER0->INTCTL_STAT = 0x00000001;
   
    // Set to 64-bit GP Timer mode, enable TIMER12 & TIMER34
    TIMER0->TGCR = 0x00000003;
   
    // Reset timers to zero
    TIMER0->TIM12 = 0x00000000;
    TIMER0->TIM34 = 0x00000000;
   
    // Set timer period (5 second timeout = (24000000 * 5) cycles = 0x07270E00)
    TIMER0->PRD34 = 0x00000000;
    TIMER0->PRD12 = 0x07270E00;
   
    return E_PASS;
}

     至此，DEVICE_init函数结束，程序返回至LOCAL_boot函数中，接着就调用NANDBOOT_copy函数了。