u-boot移植第一弹——制作可用的BL1
我的BL1源代码来源于网路，博客地址是http://blog.csdn.net/xiaojiaohuazi/article/details/8265757。在这里记录下自己的移植心得。
为什么要制作这个BL1呢，对于官方以及很多人说的它是u-boot启动的第二阶段，这里我不做过多说明，我想说的是，这个BL1可以让你对内存操作的理解更加深入，对于后面移植u-boot的理解有帮助。
实际上在BL1阶段只需要做串口和内存的初始化就可以了，初始化串口的目的是调试使用，这个是必须要的；初始化内存那不用说了，你想拷贝代码，不初始化内存怎么能行的。
但是在这里我还加入了一个LED的操作代码，为什么要加入呢，对于学习一个东西，不能说会移植了就算学会了，我想有问题的时候会调试才是更重要的，在开发时也是如此，有了调试手段就有了查错的手段，那么找问题就可以很方便的定位了。所以加入这个LED的控制目的也就是为了调试使用，这也是看到网上有人说过，仔细想想，非常好用，O(∩_∩)O。
首先看看我的BL1的所有文件：
这里只说明移植的时候涉及到的文件，build、main.c、mem_setup.S、s5pv210.h、start.S这几个文件。其中build是我加入的一个文件，目的在操作编译烧写的时候减少输入命令，build文件的内容如下：
#!/bin/sh make ./mkv210_image bl.bin blSD2.bin dd iflag=dsync oflag=dsync if=blSD2.bin of=/dev/sdc seek=1
做的工作就是编译，制作BL1，烧写到SD卡。
这个BL1启动的入口也是在start.S文件，看看做的是什么：
.text .global _start _start: bl mem_ctrl_asm_init ldr sp, =0xD0035400 bl main loop: b loop
第一步就是初始化内存也就是进入mem_ctrl_asm_init这个函数进行执行，这个函数的代码如下：
mem_ctrl_asm_init: /* DMC0 Drive Strength (Setting 2X) */ ldr r0, =ELFIN_GPIO_BASE ldr r1, =0x0000AAAA str r1, [r0, #MP1_0DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_1DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_2DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_3DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_4DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_5DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_6DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP1_7DRV_SR_OFFSET] ldr r1, =0x00002AAA str r1, [r0, #MP1_8DRV_SR_OFFSET] /* DMC1 Drive Strength (Setting 2X) */ ldr r0, =ELFIN_GPIO_BASE ldr r1, =0x0000AAAA str r1, [r0, #MP2_0DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_1DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_2DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_3DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_4DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_5DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_6DRV_SR_OFFSET] ldr r1, =0x0000AAAA str r1, [r0, #MP2_7DRV_SR_OFFSET] ldr r1, =0x00002AAA str r1, [r0, #MP2_8DRV_SR_OFFSET] /* DMC0 initialization at single Type*/ ldr r0, =APB_DMC_0_BASE ldr r1, =0x00101000 @PhyControl0 DLL parameter setting, manual 0x00101000 str r1, [r0, #DMC_PHYCONTROL0] ldr r1, =0x00000086 @PhyControl1 DLL parameter setting, LPDDR/LPDDR2 Case str r1, [r0, #DMC_PHYCONTROL1] ldr r1, =0x00101002 @PhyControl0 DLL on str r1, [r0, #DMC_PHYCONTROL0] ldr r1, =0x00101003 @PhyControl0 DLL start str r1, [r0, #DMC_PHYCONTROL0] find_lock_val: ldr r1, [r0, #DMC_PHYSTATUS] @Load Phystatus register value and r2, r1, #0x7 cmp r2, #0x7 @Loop until DLL is locked bne find_lock_val and r1, #0x3fc0 mov r2, r1, LSL #18 orr r2, r2, #0x100000 orr r2 ,r2, #0x1000 orr r1, r2, #0x3 @Force Value locking str r1, [r0, #DMC_PHYCONTROL0] #if 0 /* Memory margin test 10.01.05 */ orr r1, r2, #0x1 @DLL off str r1, [r0, #DMC_PHYCONTROL0] #endif /* setting DDR2 */ ldr r1, =0x0FFF2010 @ConControl auto refresh off str r1, [r0, #DMC_CONCONTROL] ldr r1, =DMC0_MEMCONTROL @MemControl BL=4, 2 chip, DDR2 type, dynamic self refresh, force precharge, dynamic power down off str r1, [r0, #DMC_MEMCONTROL] ldr r1, =DMC0_MEMCONFIG_0 @MemConfig0 256MB config, 8 banks,Mapping Method[12:15]0:linear, 1:linterleaved, 2:Mixed str r1, [r0, #DMC_MEMCONFIG0] ldr r1, =DMC0_MEMCONFIG_1 @MemConfig1 str r1, [r0, #DMC_MEMCONFIG1] ldr r1, =0xFF000000 @PrechConfig str r1, [r0, #DMC_PRECHCONFIG] ldr r1, =DMC0_TIMINGA_REF @TimingAref 7.8us*133MHz=1038(0x40E), 100MHz=780(0x30C), 20MHz=156(0x9C), 10MHz=78(0x4E) str r1, [r0, #DMC_TIMINGAREF] ldr r1, =DMC0_TIMING_ROW @TimingRow for @200MHz str r1, [r0, #DMC_TIMINGROW] ldr r1, =DMC0_TIMING_DATA @TimingData CL=3 str r1, [r0, #DMC_TIMINGDATA] ldr r1, =DMC0_TIMING_PWR @TimingPower str r1, [r0, #DMC_TIMINGPOWER] ldr r1, =0x07000000 @DirectCmd chip0 Deselect str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01000000 @DirectCmd chip0 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00020000 @DirectCmd chip0 EMRS2 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00030000 @DirectCmd chip0 EMRS3 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00010400 @DirectCmd chip0 EMRS1 (MEM DLL on, DQS# disable) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00000542 @DirectCmd chip0 MRS (MEM DLL reset) CL=4, BL=4 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01000000 @DirectCmd chip0 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05000000 @DirectCmd chip0 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05000000 @DirectCmd chip0 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00000442 @DirectCmd chip0 MRS (MEM DLL unreset) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00010780 @DirectCmd chip0 EMRS1 (OCD default) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00010400 @DirectCmd chip0 EMRS1 (OCD exit) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x07100000 @DirectCmd chip1 Deselect str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01100000 @DirectCmd chip1 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00120000 @DirectCmd chip1 EMRS2 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00130000 @DirectCmd chip1 EMRS3 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00110400 @DirectCmd chip1 EMRS1 (MEM DLL on, DQS# disable) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00100542 @DirectCmd chip1 MRS (MEM DLL reset) CL=4, BL=4 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01100000 @DirectCmd chip1 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05100000 @DirectCmd chip1 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05100000 @DirectCmd chip1 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00100442 @DirectCmd chip1 MRS (MEM DLL unreset) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00110780 @DirectCmd chip1 EMRS1 (OCD default) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00110400 @DirectCmd chip1 EMRS1 (OCD exit) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x0FF02030 @ConControl auto refresh on str r1, [r0, #DMC_CONCONTROL] ldr r1, =0xFFFF00FF @PwrdnConfig str r1, [r0, #DMC_PWRDNCONFIG] ldr r1, =DMC0_MEMCONTROL @MemControl 0x00202400 BL=4, 2 chip, DDR2 type, dynamic self refresh, force precharge, dynamic power down off str r1, [r0, #DMC_MEMCONTROL] /* DMC1 initialization */ ldr r0, =APB_DMC_1_BASE ldr r1, =0x00101000 @Phycontrol0 DLL parameter setting str r1, [r0, #DMC_PHYCONTROL0] ldr r1, =0x00000086 @Phycontrol1 DLL parameter setting str r1, [r0, #DMC_PHYCONTROL1] ldr r1, =0x00101002 @PhyControl0 DLL on str r1, [r0, #DMC_PHYCONTROL0] ldr r1, =0x00101003 @PhyControl0 DLL start str r1, [r0, #DMC_PHYCONTROL0] find_lock_val1: ldr r1, [r0, #DMC_PHYSTATUS] @Load Phystatus register value and r2, r1, #0x7 cmp r2, #0x7 @Loop until DLL is locked bne find_lock_val1 and r1, #0x3fc0 mov r2, r1, LSL #18 orr r2, r2, #0x100000 orr r2, r2, #0x1000 orr r1, r2, #0x3 @Force Value locking str r1, [r0, #DMC_PHYCONTROL0] #if 0 /* Memory margin test 10.01.05 */ orr r1, r2, #0x1 @DLL off str r1, [r0, #DMC_PHYCONTROL0] #endif /* settinf fot DDR2 */ ldr r0, =APB_DMC_1_BASE ldr r1, =0x0FFF2010 @auto refresh off str r1, [r0, #DMC_CONCONTROL] ldr r1, =DMC1_MEMCONTROL @MemControl BL=4, 2 chip, DDR2 type, dynamic self refresh, force precharge, dynamic power down off str r1, [r0, #DMC_MEMCONTROL] ldr r1, =DMC1_MEMCONFIG_0 @MemConfig0 512MB config, 8 banks,Mapping Method[12:15]0:linear, 1:linterleaved, 2:Mixed str r1, [r0, #DMC_MEMCONFIG0] ldr r1, =DMC1_MEMCONFIG_1 @MemConfig1 str r1, [r0, #DMC_MEMCONFIG1] ldr r1, =0xFF000000 str r1, [r0, #DMC_PRECHCONFIG] ldr r1, =DMC1_TIMINGA_REF @TimingAref 7.8us*133MHz=1038(0x40E), 100MHz=780(0x30C), 20MHz=156(0x9C), 10MHz=78(0x4 str r1, [r0, #DMC_TIMINGAREF] ldr r1, =DMC1_TIMING_ROW @TimingRow for @200MHz str r1, [r0, #DMC_TIMINGROW] ldr r1, =DMC1_TIMING_DATA @TimingData CL=3 str r1, [r0, #DMC_TIMINGDATA] ldr r1, =DMC1_TIMING_PWR @TimingPower str r1, [r0, #DMC_TIMINGPOWER] ldr r1, =0x07000000 @DirectCmd chip0 Deselect str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01000000 @DirectCmd chip0 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00020000 @DirectCmd chip0 EMRS2 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00030000 @DirectCmd chip0 EMRS3 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00010400 @DirectCmd chip0 EMRS1 (MEM DLL on, DQS# disable) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00000542 @DirectCmd chip0 MRS (MEM DLL reset) CL=4, BL=4 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01000000 @DirectCmd chip0 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05000000 @DirectCmd chip0 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05000000 @DirectCmd chip0 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00000442 @DirectCmd chip0 MRS (MEM DLL unreset) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00010780 @DirectCmd chip0 EMRS1 (OCD default) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00010400 @DirectCmd chip0 EMRS1 (OCD exit) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x07100000 @DirectCmd chip1 Deselect str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01100000 @DirectCmd chip1 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00120000 @DirectCmd chip1 EMRS2 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00130000 @DirectCmd chip1 EMRS3 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00110440 @DirectCmd chip1 EMRS1 (MEM DLL on, DQS# disable) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00100542 @DirectCmd chip1 MRS (MEM DLL reset) CL=4, BL=4 str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x01100000 @DirectCmd chip1 PALL str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05100000 @DirectCmd chip1 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x05100000 @DirectCmd chip1 REFA str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00100442 @DirectCmd chip1 MRS (MEM DLL unreset) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00110780 @DirectCmd chip1 EMRS1 (OCD default) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x00110400 @DirectCmd chip1 EMRS1 (OCD exit) str r1, [r0, #DMC_DIRECTCMD] ldr r1, =0x0FF02030 @ConControl auto refresh on str r1, [r0, #DMC_CONCONTROL] ldr r1, =0xFFFF00FF @PwrdnConfig str r1, [r0, #DMC_PWRDNCONFIG] ldr r1, =DMC1_MEMCONTROL @MemControl BL=4, 2 chip, DDR2 type, dynamic self refresh, force precharge, dynamic power down off str r1, [r0, #DMC_MEMCONTROL] //下面为点灯代码，用于调试 ldr r0, =0xE0200C00 ldr r1, =0x11000000 str r1, [r0] ldr r1, =0xc0 str r1, [r0, #4] //上面为点灯代码，用于调试 mov pc, lr
可以看到我在该函数的最后增加了LED灯的代码，具体的含义请参考帖子 http://blog.csdn.net/kevinshq/article/details/7968409不同的板子LED接口可能不同，这样的话就需要修改寄存器的地址了，也可能没有LED，如果是这种情况就需要使用其他的提醒功能来代替LED了（最好是能够看到现象的）。LED代码放在这里在启动板子的时候就可以观察LED的状态来判断内存初始化这部分代码是否启动了。
好，现在回到该函数的起始部分，对于该函数已经有人做过了分析，这里我就引用之博文地址为http://blog.csdn.net/mutemob/article/details/12974483。在这之外我们需要注意一个问题，那就是下面代码的位置处
有可能你的代码红色部分为0x00202400这种格式的16进制，最好是改成上图所示的请款个，目的是为了方便修改。
从start.S文件中可以知道，第二个执行的函数为main函数，函数位置在main.c。
main.c文件源代码请下载下来观看，这里我就不一次全部贴上来了。我们从main主函数出发，看看都做了些什么：
int main (void)
{
__attribute__((noreturn)) void (*uboot)(void);
uart_init(); //串口初始化
mem_test(); //内存测试
printf ("copy uboot from sd to sdram ddr2\r\n");
copy_uboot_to_ram();
printf ("jump to u-boot image\r\n");
//下面代码是控制班子上的LED，可用于调试
//*(volatile unsigned int *)0xE0200C00 = 0x11000000;
//*(volatile unsigned int *)0xE0200C04 = 0x000000c0;
//上面代码是控制班子上的LED，可用于调试
/* Jump to U-Boot imag
uboot = (void *)0x33e00000;
(*uboot)();
return 1;
}
开始进行了串口的初始化，然后是内存的测试，接着是u-boot的拷贝阶段，最后跳转到u-boot的位置开始执行。我的u-boot的起始地址是0x33e00000，不同的板子地址可能有所不同，请调整为自己的u-boot起始地址即可，也就是把0x33e00000换成自己的板子的地址。
串口的初始化我的板子是Real210板子，调试口使用的是串口2，所以在网络上原来的代码基础上把他的串口初始化从串口0修改到了串口2，在源码的s5pv210.h中可以看到各寄存器的定义。串口的初始化是在文件uart.c中进行，这里我不再说明，具体的请参阅s5pv210 pdf进行对比学习。
内存的测试函数mem_test()代码如下：
void mem_test()
{
#define test_mem1 0x30000000
#define test_mem2 0x33e00004
#define test_mem3 0x3f000f08
#define test_mem4 0x3ffff0fc
#define test_mem5 0x3ffffffc //内存地址是每隔4个字节存放的，所以访问时是4个字节访问
#define test_mem6 0x40000000
#define test_mem7 0x43e00004
#define test_mem8 0x4f00f008
#define test_mem9 0x4ffffff8
#define test_mem10 0x4ffffffc
unsigned int *p1 = (volatile unsigned int *)test_mem1;
unsigned int *p2 = (volatile unsigned int *)test_mem2;
unsigned int *p3 = (volatile unsigned int *)test_mem3;
unsigned int *p4 = (volatile unsigned int *)test_mem4;
unsigned int *p5 = (volatile unsigned int *)test_mem5;
unsigned int *p6 = (volatile unsigned int *)test_mem6;
unsigned int *p7 = (volatile unsigned int *)test_mem7;
unsigned int *p8 = (volatile unsigned int *)test_mem8;
unsigned int *p9 = (volatile unsigned int *)test_mem9;
unsigned int *p10 = (volatile unsigned int *)test_mem10;
printf ("******s5pv210 Test********\r\n");
printf ("********By ZheGao********\r\n");
*p1 = 0x12345678;
if (*p1 == 0x12345678) {
printf ("1: equ\r\n");
} else {
printf ("1: not equ\r\n");
}
*p2 = 0x12345678;
if (*p2 == 0x12345678) {
printf ("2: equ\r\n");
} else {
printf ("2: not equ\r\n");
}
*p3= 0xfffffff0;
if (*p3 == 0xfffffff0) {
printf ("3: equ\r\n");
} else {
printf ("3: not equ\r\n");
}
*p4 = 0x12345678;
if (*p4 == 0x12345678) {
printf ("4: equ\r\n");
} else {
printf ("4: not equ\r\n");
}
*p5 = 0x12345678;
if (*p5 == 0x12345678) {
printf ("5: equ\r\n");
} else {
printf ("5: not equ\r\n");
}
*p6= 0xfffffff0;
if (*p6 == 0xfffffff0) {
printf ("6: equ\r\n");
} else {
printf ("6: not equ\r\n");
}
*p7 = 0x12345678;
if (*p7 == 0x12345678) {
printf ("7: equ\r\n");
} else {
printf ("7: not equ\r\n");
}
*p8 = 0x12345678;
if (*p8 == 0x12345678) {
printf ("8: equ\r\n");
} else {
printf ("8: not equ\r\n");
}
*p9= 0x12345678;
if (*p9 == 0x12345678) {
printf ("9: equ\r\n");
} else {
printf ("9: not equ\r\n");
}
*p10= 0x12345678;
if (*p10 == 0x12345678) {
printf ("10: equ\r\n");
} else {
printf ("10: not equ\r\n");
}
}
从最开始宏定义可以知道测试的内存地址，这里把我板子的全部内存做了隔段测试，我的内存地址是从0x30000000到0x4fffffff总共512MB，注意在测试的时候内存地址需要隔4个字节进行测试，也就是最后一位只能取值0、4、8、c这四个值，原因是，我们的内存是32位的也就是4个字节，所以在测试访问的时候需要隔4个字节，注意不能取最后一位除0、4、8、c以外的值，否者就会死掉。
copy_uboot_to_ram()这个拷贝函数的说也参考一个博文http://blog.csdn.net/shangguobuliuhen/article/details/9844371。
同样在main函数中也有LED灯的代码，不过这次换成了C语言的写法，放在这里也是为了判断代码执行的位置，进而判断代码会死在哪里，这个LED定位的思想要灵活运用，可以为你学习和调试带来极大的帮助。就在u-boot中一样我们使用串口打印信息来进行调试一个道理。
第一阶段告一段落，后面继续更新，下一个就是让u-boot能够启动并能进入控制台，过些天在写上来吧。有问题得朋友可以留言，大家共同探讨。