DM365的UBL源码分析(三)

转自：http://blog.chinaunix.net/space.php?uid=7214824&do=blog&id=160523

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。