ARM笔记： U-Boot移植 -

U-Boot移植：
系统：Ubuntu 12.04
开发板：JZ2440
虚拟机：VM10.04
U-Boot:U-BOOT-1.1.6
步骤：
1、解压U-BOOT-1.1.6
tar jxvf U-BOOT-1.1.6.tar.bz2
2、同时支持S3C2410和S3C2440：
（1）、新建一个开发板的相应目录和文件
在board目录下将smdk2410复制为100ask24x0,并将board/100ask24x0/smdk2410.c改名为100ask24x0.c,再将include/configs/smdk2410.h复制为100ask24x0.h
修改两个Makefile:
1)、在顶层Makefile中增加如个两行：
100ask24x0_config :unconfig
@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0
2)、在board/100ask24x0/Makefile中修改如下：
COBJS:= smdk2410.o flash.o
改为
COBJS:= 100ask24x0.o flash.o
3、修改SDRAM的配置
SDRAM的初始化在U-Boot的第一阶段完成，在board/100ask24x0/lowlevel_init.S中，由于开发板的HCLK都为100mhz，需该REFCNT寄存器的值。修改如下：
#define REFCNT0x1113
改为
#define REFCNT0x4f4
4、增加对S3C2440的支持
2440的时钟计算公式、NAND操作和2410不太一样。

本文引用地址: http://www.21ic.com/app/mcu/201809/778636.htm

对于2440开发板，将FCLK设为400MHz，分频比为FCLK：HCLK：PCLK=1：4：8。

首先修改board/100ask24x0/100ask24x0.c中的board_init函数:

#define S3C2440_MPLL_400MHZ((0x5c<<12)|(0x02<<4)|(0x01))

#define S3C2440_UPLL_48MHZ((0x38<<12)|(0x02<<4)|(0x02))

#define S3C2440_CLKDIV0x05

#define S3C2410_MPLL_200MHZ((0x5c<<12)|(0x04<<4)|(0x00))

#define S3C2410_UPLL_48MHZ((0x28<<12)|(0x01<<4)|(0x02))

#define S3C2410_CLKDIV0x03

int board_init (void)

{

S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();

S3C24X0_GPIO * const gpio = S3C24X0_GetBase_GPIO();

gpio->GPACON = 0x007FFFFF;

gpio->GPBCON = 0x00044555;

gpio->GPBUP = 0x000007FF;

gpio->GPCCON = 0xAAAAAAAA;

gpio->GPCUP = 0x0000FFFF;

gpio->GPDCON = 0xAAAAAAAA;

gpio->GPDUP = 0x0000FFFF;

gpio->GPECON = 0xAAAAAAAA;

gpio->GPEUP = 0x0000FFFF;

gpio->GPFCON = 0x000055AA;

gpio->GPFUP = 0x000000FF;

gpio->GPGCON = 0xFF95FFBA;

gpio->GPGUP = 0x0000FFFF;

gpio->GPHCON = 0x002AFAAA;

gpio->GPHUP = 0x000007FF;

if ((gpio->GSTATUS1 == 0x32410000) || (gpio->GSTATUS1 == 0x32410002))

{

clk_power->CLKDIVN = S3C2410_CLKDIV;

__asm__("mrcp15, 0, r1, c1, c0, 0n"

"orrr1, r1, #0xc0000000n"

"mcrp15, 0, r1, c1, c0, 0n"

:::"r1"

);

clk_power->LOCKTIME = 0xFFFFFF;

clk_power->MPLLCON = S3C2410_MPLL_200MHZ;

delay (4000);

clk_power->UPLLCON = S3C2410_UPLL_48MHZ;

delay (8000);

gd->bd->bi_arch_number = MACH_TYPE_SMDK2410;

}

else

{

clk_power->CLKDIVN = S3C2440_CLKDIV;

__asm__("mrcp15, 0, r1, c1, c0, 0n"

"orrr1, r1, #0xc0000000n"

"mcrp15, 0, r1, c1, c0, 0n"

:::"r1"

);

clk_power->LOCKTIME = 0xFFFFFF;

clk_power->MPLLCON = S3C2440_MPLL_400MHZ;

delay (4000);

clk_power->UPLLCON = S3C2440_UPLL_48MHZ;

delay (8000);

gd->bd->bi_arch_number = MACH_TYPE_S3C2440;

}

gd->bd->bi_boot_params = 0x30000100;

icache_enable();

dcache_enable();

return 0;

}

5、修改系统时钟
在U-Boot的第二阶段，设置串口波特率时需要获得系统时钟，lib_arm/board.c中,start_armboot函数调用serial_init函数初始化时会调用get_PCLK函数。
在cpu/arm920t/s3c24x0/speed.c中修改：
首先，在程序开头增加一行DECLARE_GLOBAL_DATA_PTR;，这样才可以使用gd变量。
S3C2410和S3C2440的MPLL,UPLL计算公式不一样，所以修改get_PLLCLK:

static ulong get_PLLCLK(int pllreg)

{

S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();

ulong r, m, p, s;

if (pllreg == MPLL)

r = clk_power->MPLLCON;

else if (pllreg == UPLL)

r = clk_power->UPLLCON;

else

hang();

m = ((r & 0xFF000) >> 12) + 8;

p = ((r & 0x003F0) >> 4) + 2;

s = r & 0x3;

if (gd->bd->bi_arch_number == MACH_TYPE_SMDK2410)

return((CONFIG_SYS_CLK_FREQ * m) / (p << s));

else

return((CONFIG_SYS_CLK_FREQ * m * 2) / (p << s));

}

由于分频系数的设置方法也不一样，get_HCLK,get_PCLK也做如下修改：

#define S3C2440_CLKDIVN_PDIVN(1<<0)

#define S3C2440_CLKDIVN_HDIVN_MASK(3<<1)

#define S3C2440_CLKDIVN_HDIVN_1(0<<1)

#define S3C2440_CLKDIVN_HDIVN_2(1<<1)

#define S3C2440_CLKDIVN_HDIVN_4_8(2<<1)

#define S3C2440_CLKDIVN_HDIVN_3_6(3<<1)

#define S3C2440_CLKDIVN_UCLK(1<<3)

#define S3C2440_CAMDIVN_CAMCLK_MASK(0xf<<0)

#define S3C2440_CAMDIVN_CAMCLK_SEL(1<<4)

#define S3C2440_CAMDIVN_HCLK3_HALF(1<<8)

#define S3C2440_CAMDIVN_HCLK4_HALF(1<<9)

#define S3C2440_CAMDIVN_DVSEN(1<<12)

ulong get_HCLK(void)

{

S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();

unsigned long clkdiv;

unsigned long camdiv;

int hdiv = 1;

if (gd-