DM365的UBL源码分析

   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(flash_utils\DM36x\CCS下包括NANDWriter和UBL两个文件夹，分别对应针对IPNC的CCS的project)。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;    /*UBL结束，gEntryPoint将u-boot入口交给APPEntry*/
    (*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])));/* The first "long" is entry point for Application ，u-boot主程序将从这里开始执行*/
  gNandBoot.numPage =*(((Uint32*)(&rxBuf[8])));/* The second "long" is the number of pages ,代码总页数，有多少数据要载入到DDR*/
  gNandBoot.block =*(((Uint32*)(&rxBuf[12])));/* The third "long" is the block where Application is stored in NAND */
  gNandBoot.page =*(((Uint32*)(&rxBuf[16])));/* The fourth "long" is the page number where Application is stored in NAND */
  gNandBoot.ldAddress = *(((Uint32*)(&rxBuf[20])));/* The fifth "long" is the Application load address ,一般情况，程序放在这个地址开始加载*/


      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 )        /*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*/
    {
        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);       /*对全局变量currMemPtr赋值*/
    
    // 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){ /* Skip locked LPSCs [29-37] */
            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;
    
    /*Power up the PLL*/
    PLL1->PLLCTL&= 0xFFFFFFFD;        
    
    PLL1->PLLCTL&= 0xFFFFFEFF;             
    PLL1->PLLCTL|= CLKSRC<<8;
    
    /*Set PLLENSRC '0', PLL Enable(PLLEN) selection is controlled through MMR*/
    PLL1->PLLCTL&= 0xFFFFFFDF;    
    
    /*Set PLLEN=0 => PLL BYPASS MODE*/
    PLL1->PLLCTL&= 0xFFFFFFFE;
    
    UTIL_waitLoop(150);                 
    
    // PLLRST=1(reset assert)
    PLL1->PLLCTL|= 0x00000008; 
    
    UTIL_waitLoop(300);
    
    /*Bring PLL out of Reset*/
    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);
    
    /*Set the GOSET bit */
    PLL1->PLLCMD= 0x00000001; // Go

    UTIL_waitLoop(300);
        
    /*Wait for PLL to LOCK */
    while(!(((SYSTEM->PLL0_CONFIG)& 0x07000000) == 0x07000000));    
    
    /*Enable the PLL Bit of PLLCTL*/
    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