U-Boot在FL2440上移植（一）----修改系统时钟

<一>U-boot源码结构

图片来自韦东山的《嵌入式linux应用开发完全手册》

U-boot下载地址：ftp://ftp.denx.de/pub/u-boot/

交叉编译工具链  3.3.2

<二>U-boot移植

1.新建一个fl2440开发板目录和文件

①在board目录下新建fl2440目录，讲smdk2410目录下的文件复制到fl2440目录下，并将board/fl2440/smdk2410.c重命名为fl2440.c

②修改u-boot-1.1.6目录下Makefile文件

smdk2410_config : unconfig

@$(MKCONFIG) $(@:_config=) arm arm920t smdk2410 NULL s3c24x0

后面加上

fl2410_config : unconfig

@$(MKCONFIG) $(@:_config=) arm arm920t fl2410 NULL s3c24x0

然后在board/fl2440/Makefile中修改

COBJS := smdk2410.o flash.o    为   COBJS := fl2440.o flash.o

2.修改SDRAM的配置

①修改board/fl2440/lowlevel_init.s文件中的126行

#define REFCNT    0x4f4

②

修改board/fl2440/fl2440.c中的board_init函数，即替换掉整个函数board_init包括它本身的所有语句。

#define S3C2440_MPLL_400MHZ ((0x7f<<12)|(0x02<<4)|(0x01))

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

#define S3C2440_CLKDIV 0x05

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

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

#define S3C2410_CLKDIV 0x03

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__( "mrc p15, 0, r1, c1, c0, 0\n"

"orr r1, r1, #0xc0000000\n"

"mcr p15, 0, r1, c1, c0, 0\n"

:::"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__( "mrc p15, 0, r1, c1, c0, 0\n"

"orr r1, r1, #0xc0000000\n"

"mcr p15, 0, r1, c1, c0, 0\n"

:::"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;

}

③S3C2410和S3C2440的MPLL，UPLL计算公式不一样，所以get_PLLCLK函数也需要修改

在cpu/arm920t/s3c24X0/speed.c中修改：

修改get_PLLCLK函数：

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));

}

即在get_PLLCLK函数下加入上面的红色字体。

修改get_HCLK, get_PCLK（直接粘贴下面代码，来把这个两个函数覆盖掉）:

#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_ LK (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->bd->bi_arch_number == MACH_TYPE_SMDK2410)

return((clk_power->CLKDIVN & 0x2) ? get_FCLK()/2 : get_FCLK());

else

{

clkdiv = clk_power->CLKDIVN;

camdiv = clk_power->CAMDIVN;

switch (clkdiv & S3C2440_CLKDIVN_HDIVN_MASK) {

case S3C2440_CLKDIVN_HDIVN_1:

hdiv = 1;

break;

case S3C2440_CLKDIVN_HDIVN_2:

hdiv = 2;

break;

case S3C2440_CLKDIVN_HDIVN_4_8:

hdiv = (camdiv & S3C2440_CAMDIVN_HCLK4_HALF) ? 8 : 4;

break;

case S3C2440_CLKDIVN_HDIVN_3_6:

hdiv = (camdiv & S3C2440_CAMDIVN_HCLK3_HALF) ? 6 : 3;

break;

}

return get_FCLK() / hdiv;

}

}

ulong get_PCLK(void)

{

S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();

unsigned long clkdiv;

unsigned long camdiv;

int hdiv = 1;

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

return((clk_power->CLKDIVN & 0x1) ? get_HCLK()/2 : get_HCLK());

else

{

clkdiv = clk_power->CLKDIVN;

camdiv = clk_power->CAMDIVN;

switch (clkdiv & S3C2440_CLKDIVN_HDIVN_MASK) {

case S3C2440_CLKDIVN_HDIVN_1:

hdiv = 1;

break;

case S3C2440_CLKDIVN_HDIVN_2:

hdiv = 2;

break;

case S3C2440_CLKDIVN_HDIVN_4_8:

hdiv = (camdiv & S3C2440_CAMDIVN_HCLK4_HALF) ? 8 : 4;

break;

case S3C2440_CLKDIVN_HDIVN_3_6:

hdiv = (camdiv & S3C2440_CAMDIVN_HCLK3_HALF) ? 6 : 3;

break;

}

return get_FCLK() / hdiv / ((clkdiv & S3C2440_CLKDIVN_PDIVN)? 2:1);

}

}

重新执行make fl2440_config make all 生成u-boot.bin，由于还没有增加NAND Flash的支持，所以可烧入NOR Flash中运行

在make all时会出现错误：没有CAMDIVN

这个要在include/s3c24x0.h头文件中定义，在129行S3C24X0_CLOCK_POWER结构体中增加：S3C24X0_REG32 CAMDIVN;

现在执行 make fl2440_config 和 make all生成U-Boot.bin就可以烧入norflash了。