init_fnc_t *init_sequence[] = {
cpu_init, /* basic cpu dependent setup */
board_init, /* basic board dependent setup */
interrupt_init, /* set up exceptions */
env_init, /* initialize environment */
init_baudrate, /* initialze baudrate settings */
serial_init, /* serial communications setup */
console_init_f, /* stage 1 init of console */
display_banner, /* say that we are here */
dram_init, /* configure available RAM banks */
display_dram_config,
#if defined(CONFIG_VCMA9) || defined (CONFIG_CMC_PU2) /*smdk2410没有定义*/
checkboard,
#endif
NULL,
};
谭浩强的书上写着，一维指针数组的定义形式为： 类型名 * 数组名[数组长度]；
可见，这里的init_sequence也是指针数组，数组名为init_sequence，数组的每一个元素都为指针类型，在这里每个元素是指向函数的指针。init_fnc_ptr即为指向init_sequence指针数组的指针，结合起这里来就可以理解了.
下面就跳到数组的第一个函数cpu_init去执行：
int cpu_init (void)
{
#ifdef CONFIG_USE_IRQ
DECLARE_GLOBAL_DATA_PTR;
IRQ_STACK_START = _armboot_start - CFG_MALLOC_LEN - CFG_GBL_DATA_SIZE - 4;
FIQ_STACK_START = IRQ_STACK_START - CONFIG_STACKSIZE_IRQ;
#endif
return 0;
}
实际上这里只是什么都不干，因为在u-boot-1.1.4\include\configs\smdk2410.h里没有定义CONFIG_USE_IRQ
#undef CONFIG_USE_IRQ /* we don't need IRQ/FIQ stuff */
接下来是board_init函数，先贴出代码稍后再分析：
int board_init (void)
{
DECLARE_GLOBAL_DATA_PTR;
S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();
S3C24X0_GPIO * const gpio = S3C24X0_GetBase_GPIO();
/* to reduce PLL lock time, adjust the LOCKTIME register */
clk_power->LOCKTIME = 0xFFFFFF;
/* configure MPLL */
clk_power->MPLLCON = ((M_MDIV << 12) + (M_PDIV << 4) + M_SDIV);
/* some delay between MPLL and UPLL */
delay (4000);
/* configure UPLL */
clk_power->UPLLCON = ((U_M_MDIV << 12) + (U_M_PDIV << 4) + U_M_SDIV);
/* some delay between MPLL and UPLL */
delay (8000);
/* set up the I/O ports */
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;
/* arch number of SMDK2410-Board */
gd->bd->bi_arch_number = MACH_TYPE_SMDK2410;
/* adress of boot parameters */
gd->bd->bi_boot_params = 0x30000100;
icache_enable();
dcache_enable();
return 0;
}
首先这里有S3C24X0_CLOCK_POWER结构体类型，搜索到它是在u-boot-1.1.4\include\s3c24x0.h中定义的
/* CLOCK & POWER MANAGEMENT (see S3C2400 manual chapter 6) */
/* (see S3C2410 manual chapter 7) */
typedef struct {
S3C24X0_REG32 LOCKTIME;
S3C24X0_REG32 MPLLCON;
S3C24X0_REG32 UPLLCON;
S3C24X0_REG32 CLKCON;
S3C24X0_REG32 CLKSLOW;
S3C24X0_REG32 CLKDIVN;
} /*__attribute__((__packed__))*/ S3C24X0_CLOCK_POWER;
其中S3C24X0_REG32在同一个文件中有定义：
typedef volatile u32 S3C24X0_REG32;
S3C24X0_GetBase_CLOCK_POWER在u-boot-1.1.4\include\s3c2410.h中定义如下：
static inline S3C24X0_CLOCK_POWER * const S3C24X0_GetBase_CLOCK_POWER(void)
{
return (S3C24X0_CLOCK_POWER * const)S3C24X0_CLOCK_POWER_BASE;
}
S3C24X0_CLOCK_POWER_BASE也在同一个文件中定义：
#define S3C24X0_CLOCK_POWER_BASE 0x4C000000
这里的意思是所有寄存器都通过结构体变量来存取，而不像我们裸机编程是各个寄存器一个个的定义。S3C24X0_GPIO结构体同S3C24X0_CLOCK_POWER，这里不再详述.
接着设置时钟频率，设置I/O口，接下来，
/* arch number of SMDK2410-Board */
gd->bd->bi_arch_number = MACH_TYPE_SMDK2410;
这里回到我们的bd_t中，那里有个成员：bi_arch_number;
定义是这样的的：ulong bi_arch_number; /* unique id for this board */
这里给它赋值.在u-boot-1.1.4\include\asm-arm\mach-types.h中#define MACH_TYPE_SMDK2410 193
这里的MACH_TYPE_SMDK2410应该到时传递给内核以用来识别开发板类型的.
/* adress of boot parameters */
gd->bd->bi_boot_params = 0x30000100;
bi_boot_params为传递给内核的参数的地址.
接着设置指令cache,数据cache:
icache_enable();
dcache_enable();
这两个函数定义在u-boot-1.1.4\cpu\arm920t\cpu.c中
void icache_enable (void)
{
ulong reg;
reg = read_p15_c1 (); /* get control reg. */
cp_delay ();
write_p15_c1 (reg | C1_IC);
}
void dcache_enable (void)
{
ulong reg;
reg = read_p15_c1 ();
cp_delay ();
write_p15_c1 (reg | C1_DC);
}
其中read_p15_c1在同一个文件中定义，mrc指令用英文这样记：mov cp to reg，这里是把cp15的寄存器1读到%0（不太清楚这个内嵌语法）.
/* read co-processor 15, register #1 (control register) */
static unsigned long read_p15_c1 (void)
{
unsigned long value;
__asm__ __volatile__(
"mrc p15, 0, %0, c1, c0, 0 @ read control reg\n"
: "=r" (value)
:
: "memory");
#ifdef MMU_DEBUG
printf ("p15/c1 is = %08lx\n", value);
#endif
return value;
}
write_p15_c1 (reg | C1_IC);是设置指令cache，其中C1_IC在同一文件中定义#define C1_IC (1<<12) /* icache off/on */
write_p15_c1 (reg | C1_DC);是设置数据cache，其中C1_DC在同一文件中定义#define C1_DC (1<<2) /* dcache off/on */
/* write to co-processor 15, register #1 (control register) */
static void write_p15_c1 (unsigned long value)
{
#ifdef MMU_DEBUG
printf ("write %08lx to p15/c1\n", value);
#endif
__asm__ __volatile__(
"mcr p15, 0, %0, c1, c0, 0 @ write it back\n"
:
: "r" (value)
: "memory");
read_p15_c1 (); /*这里read_p15_c1应该纯粹是为了支持*/
}
board_init函数到这里就分析完了，实际上就是设置了一些寄存器，如时钟，IO口，串口，机器类型，启动参数，指令cache,数据cache.
然后到interrupt_init了，
int interrupt_init (void)
{
S3C24X0_TIMERS * const timers = S3C24X0_GetBase_TIMERS();
/* use PWM Timer 4 because it has no output */
/* prescaler for Timer 4 is 16 */
timers->TCFG0 = 0x0f00;
if (timer_load_val == 0)
{
/*
* for 10 ms clock period @ PCLK with 4 bit divider = 1/2
* (default) and prescaler = 16. Should be 10390
* @33.25MHz and 15625 @ 50 MHz
*/
timer_load_val = get_PCLK()/(2 * 16 * 100);
}
/* load value for 10 ms timeout */
lastdec = timers->TCNTB4 = timer_load_val;
/* auto load, manual update of Timer 4 */
timers->TCON = (timers->TCON & ~0x0700000) | 0x600000;
/* auto load, start Timer 4 */
timers->TCON = (timers->TCON & ~0x0700000) | 0x500000;
timestamp = 0;
return (0);
}
结构体S3C24X0_TIMERS同前面的S3C24X0_CLOCK_POWER一样，也在u-boot-1.1.4\include\s3c24x0.h中定义
typedef struct {
S3C24X0_REG32 TCFG0;
S3C24X0_REG32 TCFG1;
S3C24X0_REG32 TCON;
S3C24X0_TIMER ch[4];
S3C24X0_REG32 TCNTB4;
S3C24X0_REG32 TCNTO4;
} /*__attribute__((__packed__))*/ S3C24X0_TIMERS;
这里的寄存器没什么，对照2410数据手册就知道怎么设置了.其中的S3C24X0_GetBase_TIMERS函数在u-boot-1.1.4\include\s3c2410.h中定义
static inline S3C24X0_TIMERS * const S3C24X0_GetBase_TIMERS(void)
{
return (S3C24X0_TIMERS * const)S3C24X0_TIMER_BASE;
}
S3C24X0_TIMER_BASE也在同一个文件中定义：
#define S3C24X0_TIMER_BASE 0x51000000
timers->TCFG0 = 0x0f00; 这里用到timer4，只用到预分频器1，这里设置TCFG0[15：8]=0x0f，[7：0]=0（没用到）.
在u-boot-1.1.4\cpu\arm920t\s3c24x0\interrupts.c中定义了int timer_load_val = 0;
timer_load_val = get_PCLK()/(2 * 16 * 100);
/*TCFG1没有设置，默认为2分频，定时器4的计数值可以由get_PCLK()/(2 * 16 * 100)算得*/
get_PCLK这个函数在u-boot-1.1.4\cpu\arm920t\s3c24x0\speed.c中:
/* return PCLK frequency */
ulong get_PCLK(void)
{
S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();
return((clk_power->CLKDIVN & 0x1) ? get_HCLK()/2 : get_HCLK());
}
这里又从PCLK根据分频设置又从get_HCLK()/2或get_HCLK()中得到：
/* return HCLK frequency */
ulong get_HCLK(void)
{
S3C24X0_CLOCK_POWER * const clk_power = S3C24X0_GetBase_CLOCK_POWER();
return((clk_power->CLKDIVN & 0x2) ? get_FCLK()/2 : get_FCLK());
}
而这里HCLK又根据分频设置get_FCLK/2或get_FCLK中得到：
/* return FCLK frequency */
ulong get_FCLK(void)
{
return(get_PLLCLK(MPLL));
}
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;
return((CONFIG_SYS_CLK_FREQ * m) / (p << s));
}
在u-boot-1.1.4\include\configs\smdk2410.h中定义有：
/* input clock of PLL */
#define CONFIG_SYS_CLK_FREQ 12000000/* the SMDK2410 has 12MHz input clock */
我们的板子也是这个频率，所以很多和时钟有关的参数都不用修改.
接着设置timer4定时器的计数值，手动加载，设置自动重载，开启定时器，具体设置就不详细分析了.
/* load value for 10 ms timeout */
lastdec = timers->TCNTB4 = timer_load_val;
/* auto load, manual update of Timer 4 */
timers->TCON = (timers->TCON & ~0x0700000) | 0x600000;
/* auto load, start Timer 4 */
timers->TCON = (timers->TCON & ~0x0700000) | 0x500000;
到这里interrupt_init分析结束
下面到env_init函数，搜索到u-boot有很多个env_init，在u-boot-1.1.4\common\env_flash.c中有这么一句：
#if defined(CFG_ENV_IS_IN_FLASH) /* Environment is in Flash */
正是因为在u-boot-1.1.4\include\configs\smdk2410.h中定义了CFG_ENV_IS_IN_FLASH，而其他的CFG_ENV_IS_IN_NAND等没有被定义，所以只有env_flash.c被编译
#define CFG_ENV_IS_IN_FLASH 1
下面就跳到env_flash.c中的env_init去分析，这个文件里也有两个env_init函数，第一个是在CFG_ENV_ADDR_REDUND有定义的情况才去编译的，而u-boot-1.1.4\include\configs\smdk2410.h没有定义这个宏，所以只有第二个env_init会实际被执行：
int env_init(void)
{
DECLARE_GLOBAL_DATA_PTR;
#ifdef CONFIG_OMAP2420H4
int flash_probe(void);
if(flash_probe() == 0)
goto bad_flash;
#endif
if (crc32(0, env_ptr->data, ENV_SIZE) == env_ptr->crc) {
gd->env_addr = (ulong)&(env_ptr->data);
gd->env_valid = 1;
return(0);
}
#ifdef CONFIG_OMAP2420H4
bad_flash:
#endif
gd->env_addr = (ulong)&default_environment[0];
gd->env_valid = 0;
return (0);
}
对于smdk2410开发板，CONFIG_OMAP2420H4这个宏没有被定义，所以中间那段跳过.
这里是设置了gd_t类型的指针变量gd，这里是用env_addr变量来存放default_environment数组的地址.
env_valid为CRD校验标志，这里设置为无效.default_environment在u-boot-1.1.4\common\env_common.c中定义：
uchar default_environment[] = {
#ifdef CONFIG_BOOTARGS /*smdk2410开发板中没有定义*/
"bootargs=" CONFIG_BOOTARGS "\0"
#endif
#ifdef CONFIG_BOOTCOMMAND /*smdk2410开发板中没有定义*/
"bootcmd=" CONFIG_BOOTCOMMAND "\0"
#endif
#ifdef CONFIG_RAMBOOTCOMMAND /*smdk2410开发板中没有定义*/
"ramboot=" CONFIG_RAMBOOTCOMMAND "\0"
#endif
#ifdef CONFIG_NFSBOOTCOMMAND /*smdk2410开发板中没有定义*/
"nfsboot=" CONFIG_NFSBOOTCOMMAND "\0"
#endif
#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0) /*smdk2410中有定义*/
"bootdelay=" MK_STR(CONFIG_BOOTDELAY) "\0"
#endif /*smdk2410中有定义*/
#if defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0)
"baudrate=" MK_STR(CONFIG_BAUDRATE) "\0"
#endif /*smdk2410开发板中没有定义*/
#ifdef CONFIG_LOADS_ECHO
"loads_echo=" MK_STR(CONFIG_LOADS_ECHO) "\0"
#endif
#ifdef CONFIG_ETHADDR /*smdk2410开发板中没有定义*/
"ethaddr=" MK_STR(CONFIG_ETHADDR) "\0"
#endif
#ifdef CONFIG_ETH1ADDR /*smdk2410开发板中没有定义*/
"eth1addr=" MK_STR(CONFIG_ETH1ADDR) "\0"
#endif
#ifdef CONFIG_ETH2ADDR /*smdk2410开发板中没有定义*/
"eth2addr=" MK_STR(CONFIG_ETH2ADDR) "\0"
#endif
#ifdef CONFIG_ETH3ADDR /*smdk2410开发板中没有定义*/
"eth3addr=" MK_STR(CONFIG_ETH3ADDR) "\0"
#endif
#ifdef CONFIG_IPADDR /*smdk2410中有定义*/
"ipaddr=" MK_STR(CONFIG_IPADDR) "\0"
#endif
#ifdef CONFIG_SERVERIP /*smdk2410中有定义*/
"serverip=" MK_STR(CONFIG_SERVERIP) "\0"
#endif
#ifdef CFG_AUTOLOAD /*smdk2410开发板中没有定义*/
"autoload=" CFG_AUTOLOAD "\0"
#endif
#ifdef CONFIG_PREBOOT /*smdk2410开发板中没有定义*/
"preboot=" CONFIG_PREBOOT "\0"
#endif
#ifdef CONFIG_ROOTPATH /*smdk2410开发板中没有定义*/
"rootpath=" MK_STR(CONFIG_ROOTPATH) "\0"
#endif
#ifdef CONFIG_GATEWAYIP /*smdk2410开发板中没有定义*/
"gatewayip=" MK_STR(CONFIG_GATEWAYIP) "\0"
#endif
#ifdef CONFIG_NETMASK /*smdk2410中有定义*/
"netmask=" MK_STR(CONFIG_NETMASK) "\0"
#endif
#ifdef CONFIG_HOSTNAME /*smdk2410开发板中没有定义*/
"hostname=" MK_STR(CONFIG_HOSTNAME) "\0"
#endif
#ifdef CONFIG_BOOTFILE /*smdk2410开发板中没有定义*/
"bootfile=" MK_STR(CONFIG_BOOTFILE) "\0"
#endif
#ifdef CONFIG_LOADADDR /*smdk2410开发板中没有定义*/
"loadaddr=" MK_STR(CONFIG_LOADADDR) "\0"
#endif
#ifdef CONFIG_CLOCKS_IN_MHZ /*smdk2410开发板中没有定义*/
"clocks_in_mhz=1\0"
#endif /*smdk2410开发板中没有定义*/
#if defined(CONFIG_PCI_BOOTDELAY) && (CONFIG_PCI_BOOTDELAY > 0)
"pcidelay=" MK_STR(CONFIG_PCI_BOOTDELAY) "\0"
#endif
#ifdef CONFIG_EXTRA_ENV_SETTINGS
CONFIG_EXTRA_ENV_SETTINGS
#endif
"\0"
};
MK_STR宏的作用是将一个字符串转化为一个值，这个宏在其他文件中也有定义，但ENV_IS_EMBEDDED没有被定义，所以Environment.c中MK_STR宏也就没有定义.只有在u-boot-1.1.4\common\env_common.c里定义了.
env_init分析完，接下来到init_baudrate了：
static int init_baudrate (void)
{
DECLARE_GLOBAL_DATA_PTR;
uchar tmp[64]; /* long enough for environment variables */
int i = getenv_r ("baudrate", tmp, sizeof (tmp));
gd->bd->bi_baudrate = gd->baudrate = (i > 0)
? (int) simple_strtoul (tmp, NULL, 10)
: CONFIG_BAUDRATE;
return (0);
}
getenv_r在u-boot-1.1.4\common\cmd_nvedit.c里面，这个函数有一点点复杂，大概意思是取出和name匹配的参数的值，存放到tmp里去
int getenv_r (char *name, char *buf, unsigned len)
{
int i, nxt;
for (i=0; env_get_char(i) != '\0'; i=nxt+1) {
int val, n;
for (nxt=i; env_get_char(nxt) != '\0'; ++nxt) {
if (nxt >= CFG_ENV_SIZE) {
return (-1);
}
}
if ((val=envmatch((uchar *)name, i)) < 0)
continue;
/* found; copy out */
n = 0;
while ((len > n++) && (*buf++ = env_get_char(val++)) != '\0') /*这个循环是把等号后面的参数值拷贝到buf中*/
;
if (len == n)
*buf = '\0';
return (n);
}
return (-1);
}
env_get_char在u-boot-1.1.4\common\env_common.c中定义如下：
uchar (*env_get_char)(int) = env_get_char_init;
继续搜索env_get_char_init，也在同一文件中：
static uchar env_get_char_init (int index)
{
DECLARE_GLOBAL_DATA_PTR;
uchar c;
/* if crc was bad, use the default environment */
if (gd->env_valid) /*刚才设置了env_valid=0，所以这里采用默认的值*/
{
c = env_get_char_spec(index);
} else {
c = default_environment[index];
}
return (c);
}
envmatch((uchar *)name, i)在u-boot-1.1.4\common\cmd_nvedit.c中定义，表示从i位置开始查找和name匹配的字符串
static int envmatch (uchar *s1, int i2)
{
while (*s1 == env_get_char(i2++))
if (*s1++ == '=') /*如果等号前面的字符串都匹配，则取出等号前面的字符串*/
return(i2);
if (*s1 == '\0' && env_get_char(i2-1) == '=') /*这种情况应该极少出现吧*/
return(i2);
return(-1);
}
继续执行init_baudrate，这里如果参数值不为0则设置为对应值，为0则采用默认值.
gd->bd->bi_baudrate = gd->baudrate = (i > 0)
? (int) simple_strtoul (tmp, NULL, 10)
: CONFIG_BAUDRATE;
simple_strtoul 这个函数在u-boot-1.1.4\lib_generic\vsprintf.c下面定义,从字面上看，这个函数的意思是str to ul(unsigned long)，但它的实现有点复杂，就不去分析了.
接下来到u-boot-1.1.4\cpu\arm920t\s3c24x0\serial.c看下serial_init，这个函数很简单，就是调用了serial_setbrg();
int serial_init (void)
{
serial_setbrg ();
return (0);
}
在同一个文件中定义了serial_setbrg，主要是设置串口控制寄存器，模块时钟，波特率等
void serial_setbrg (void)
{
DECLARE_GLOBAL_DATA_PTR;
S3C24X0_UART * const uart = S3C24X0_GetBase_UART(UART_NR);
int i;
unsigned int reg = 0;
/* value is calculated so : (int)(PCLK/16./baudrate) -1 */
reg = get_PCLK() / (16 * gd->baudrate) - 1;
/* FIFO enable, Tx/Rx FIFO clear */
uart->UFCON = 0x07;
uart->UMCON = 0x0;
/* Normal,No parity,1 stop,8 bit */
uart->ULCON = 0x3;
/*
* tx=level,rx=edge,disable timeout int.,enable rx error int.,
* normal,interrupt or polling
*/
uart->UCON = 0x245;
uart->UBRDIV = reg;
#ifdef CONFIG_HWFLOW
uart->UMCON = 0x1; /* RTS up */
#endif
for (i = 0; i < 100; i++);
}
接下来分析console_init_f，这个函数也比较简单
/* Called before relocation - use serial functions */
int console_init_f (void)
{
DECLARE_GLOBAL_DATA_PTR;
gd->have_console = 1; /*设置串口初始化标志，应该是表示串口已可用*/
#ifdef CONFIG_SILENT_CONSOLE /*CONFIG_SILENT_CONSOLE这个宏smdk2410没有定义到，所以这里跳过*/
if (getenv("silent") != NULL)
gd->flags |= GD_FLG_SILENT;
#endif
return (0);
}
接下来继续看display_banner这个函数，printf不是从标准C库里调用的，这里是重复定义了这个函数，它的调用顺序是printf->vsprintf->puts->serial_puts.最后是把一些信息直接输出到串口上.
static int display_banner (void)
{
printf ("\n\n%s\n\n", version_string);
printf ("U-Boot code: %08lX -> %08lX BSS: -> %08lX\n",
_armboot_start, _bss_start, _bss_end);
#ifdef CONFIG_MODEM_SUPPORT /*smdk2410没有定义CONFIG_MODEM_SUPPORT这个宏，这里跳过*/
puts ("Modem Support enabled\n");
#endif
#ifdef CONFIG_USE_IRQ /*这个smdk2410也没有定义*/
printf ("IRQ Stack: %08lx\n", IRQ_STACK_START);
printf ("FIQ Stack: %08lx\n", FIQ_STACK_START);
#endif
return (0);
}
搜索到version_string的定义，其中U_BOOT_VERSION定义为"U-Boot 1.1.4"，即把这个字符串打印到串口上.
const char version_string[] =
U_BOOT_VERSION" (" __DATE__ " - " __TIME__ ")"CONFIG_IDENT_STRING;
然后输出_armboot_start, _bss_start, _bss_end等地址信息.
按照顺序下来，下面是dram_init，这个函数比较简单，就是初始化板子的sdram起始地址及容量大小.
int dram_init (void)
{
DECLARE_GLOBAL_DATA_PTR;
gd->bd->bi_dram[0].start = PHYS_SDRAM_1;
gd->bd->bi_dram[0].size = PHYS_SDRAM_1_SIZE;
return 0;
}
在smdk2410.h中定义了下面两个宏
#define PHYS_SDRAM_1 0x30000000 /* SDRAM Bank #1 */
#define PHYS_SDRAM_1_SIZE 0x04000000 /* 64 MB */
回到之前的bd_t结构体里，其成员里有个bi_dram结构体数组，其中CONFIG_NR_DRAM_BANKS表示板子的dram的数目，这里我们只用到了一个sdram，所以只初始化了bi_dram[0].
struct /* RAM configuration */
{
ulong start;
ulong size;
} bi_dram[CONFIG_NR_DRAM_BANKS];
初始化完dram，下面就打印dram有关的信息：
static int display_dram_config (void)
{
DECLARE_GLOBAL_DATA_PTR;
int i;
puts ("RAM Configuration:\n");
for(i=0; i printf ("Bank #%d: %08lx ", i, gd->bd->bi_dram[i].start);
print_size (gd->bd->bi_dram[i].size, "\n");
}
return (0);
}
回到之前的循环，执行完之后继续运行下去，下面是flash_init().
for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
if ((*init_fnc_ptr)() != 0) {
hang ();
}
}
/* configure available FLASH banks */
size = flash_init ();
display_flash_config (size);
这里的flash_init是在u-boot-1.1.4\board\smdk2410\flash.c里面的，对于smdk2410，它只实现了AMD_LV400/AMD_LV800的flash操作,对于我们板子的SST39VF1601，在移植的时候这个需要改写，这里先分析smdk2410是怎么实现的.
ulong flash_init (void)
{
int i, j;
ulong size = 0;
for (i = 0; i < CFG_MAX_FLASH_BANKS; i++) {
ulong flashbase = 0; /*flashbase是flash的物理起始地址*/
flash_info[i].flash_id =
#if defined(CONFIG_AMD_LV400)
(AMD_MANUFACT & FLASH_VENDMASK) |
(AMD_ID_LV400B & FLASH_TYPEMASK);
#elif defined(CONFIG_AMD_LV800)
(AMD_MANUFACT & FLASH_VENDMASK) |
(AMD_ID_LV800B & FLASH_TYPEMASK);
#else
#error "Unknown flash configured"
#endif
flash_info[i].size = FLASH_BANK_SIZE; /*flash的容量大小*/
flash_info[i].sector_count = CFG_MAX_FLASH_SECT; /*flash的总扇区数*/
memset (flash_info[i].protect, 0, CFG_MAX_FLASH_SECT); /*flash的保护标志*/
if (i == 0)
flashbase = PHYS_FLASH_1;
else
panic ("configured too many flash banks!\n");
for (j = 0; j < flash_info[i].sector_count; j++) {
if (j <= 3) {
/* 1st one is 16 KB */
if (j == 0) {
flash_info[i].start[j] = /*flash的扇区起始地址*/
flashbase + 0;
}
/* 2nd and 3rd are both 8 KB */
if ((j == 1) || (j == 2)) {
flash_info[i].start[j] =
flashbase + 0x4000 + (j -
1) *
0x2000;
}
/* 4th 32 KB */
if (j == 3) {
flash_info[i].start[j] =
flashbase + 0x8000;
}
} else {
flash_info[i].start[j] =
flashbase + (j - 3) * MAIN_SECT_SIZE;
}
}
size += flash_info[i].size;
}
flash_protect (FLAG_PROTECT_SET, /*FLAG_PROTECT_SET在include\flash.h中定义为0x01*/
CFG_FLASH_BASE,
CFG_FLASH_BASE + monitor_flash_len - 1,
&flash_info[0]);
flash_protect (FLAG_PROTECT_SET,
CFG_ENV_ADDR,
CFG_ENV_ADDR + CFG_ENV_SIZE - 1, &flash_info[0]);
return size;
}
这里有个FLASH Info，搜索到它的定义在u-boot-1.1.4\include\flash.h中
* FLASH Info: contains chip specific data, per FLASH bank
*/
typedef struct {
ulong size; /* total bank size in bytes */
ushort sector_count; /* number of erase units */
ulong flash_id; /* combined device & manufacturer code */
ulong start[CFG_MAX_FLASH_SECT]; /* physical sector start addresses */
uchar protect[CFG_MAX_FLASH_SECT]; /* sector protection status */
#ifdef CFG_FLASH_CFI
uchar portwidth; /* the width of the port */
uchar chipwidth; /* the width of the chip */
ushort buffer_size; /* # of bytes in write buffer */
ulong erase_blk_tout; /* maximum block erase timeout */
ulong write_tout; /* maximum write timeout */
ulong buffer_write_tout; /* maximum buffer write timeout */
ushort vendor; /* the primary vendor id */
ushort cmd_reset; /* Vendor specific reset command */
ushort interface; /* used for x8/x16 adjustments */
#endif
} flash_info_t;
而在smdk2410.h中有如下定义：
flash_info_t flash_info[CFG_MAX_FLASH_BANKS]; /*其中CFG_MAX_FLASH_BANKS为flash的数目，smdk2410定义为0，所以只有一个flash_info，就是flash_info[0]*/
#define FLASH_BANK_SIZE PHYS_FLASH_SIZE
PHYS_FLASH_SIZE在u-boot-1.1.4\include\configs\smdk2410.h中定义了为512K大小.而SST39VF1601为2M大小的，CFG_MAX_FLASH_SECT为flash的总扇区数，
#define PHYS_FLASH_SIZE 0x00080000 /* 512KB */
#define CFG_MAX_FLASH_SECT (11) /* max number of sectors on one chip */
对于SST39VF1601，可以采用sector的方法也可以采用block的方法，其中
1 sector=2k word=4k byte，
1 block=32k word=64k byte，
所以共有2048k/64k个block，即32个block,这些移植的时候需要修改.
上面flash_init()里面有个flash_protect()，把它找出来了，看看它都干了些什么
/*-----------------------------------------------------------------------
* Set protection status for monitor sectors
*
* The monitor is always located in the _first_ Flash bank.
* If necessary you have to map the second bank at lower addresses.
*/
void flash_protect (int flag, ulong from, ulong to, flash_info_t *info)
{
ulong b_end = info->start[0] + info->size - 1; /* bank end address */
short s_end = info->sector_count - 1; /* index of last sector */
int i;
/*------------------------（开始）实际上这里没有被定义----------------------*/
debug ("flash_protect %s: from 0x%08lX to 0x%08lX\n",
(flag & FLAG_PROTECT_SET) ? "ON" :
(flag & FLAG_PROTECT_CLEAR) ? "OFF" : "???",
from, to);
/*------------------------（结束）实际上这里没有被定义----------------------*/
/* Do nothing if input data is bad. */
if (info->sector_count == 0 || info->size == 0 || to < from) {
return;
}
/* There is nothing to do if we have no data about the flash
* or the protect range and flash range don't overlap.
*/
if (info->flash_id == FLASH_UNKNOWN ||
to < info->start[0] || from > b_end) {
return;
}
for (i=0; isector_count; ++i) {
ulong end; /* last address in current sect */
end = (i == s_end) ? b_end : info->start[i + 1] - 1;
/* Update protection if any part of the sector
* is in the specified range.
*/
if (from <= end && to >= info->start[i]) {
if (flag & FLAG_PROTECT_CLEAR) {
#if defined(CFG_FLASH_PROTECTION) /*这个宏没有被定义，跳过*/
flash_real_protect(info, i, 0);
#else
info->protect[i] = 0;
#endif /* CFG_FLASH_PROTECTION */
debug ("protect off %d\n", i);
}
else if (flag & FLAG_PROTECT_SET) {
#if defined(CFG_FLASH_PROTECTION) /*这个宏没有被定义，跳过*/
flash_real_protect(info, i, 1);
#else
info->protect[i] = 1;
#endif /* CFG_FLASH_PROTECTION */
debug ("protect on %d\n", i);
}
}
}
}
原来实际上在smdk2410中它等于什么都不干，看来白费我工夫了.
继续分析flash_init后面的display_flash_config，size为所有flash的总大小，这里只有一个flash，所以size=flash_info[0]
static void display_flash_config (ulong size)
{
puts ("Flash: ");
print_size (size, "\n");
}
继续回到start_armboot()，
#ifdef CONFIG_VFD
# ifndef PAGE_SIZE
# define PAGE_SIZE 4096
# endif
/*
* reserve memory for VFD display (always full pages)
*/
/* bss_end is defined in the board-specific linker script */
addr = (_bss_end + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
size = vfd_setmem (addr);
gd->fb_base = addr;
#endif /* CONFIG_VFD */
#ifdef CONFIG_LCD
# ifndef PAGE_SIZE
# define PAGE_SIZE 4096
# endif
/*
* reserve memory for LCD display (always full pages)
*/
/* bss_end is defined in the board-specific linker script */
addr = (_bss_end + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
size = lcd_setmem (addr);
gd->fb_base = addr;
#endif /* CONFIG_LCD */
这两段没有被定义，跳过.
/* armboot_start is defined in the board-specific linker script */
mem_malloc_init (_armboot_start - CFG_MALLOC_LEN); /*_armboot_start等于连接时_start的地址，即为0x33f80000*/
其中mem_malloc_init的定义如下，主要是清除内存区域.
static void mem_malloc_init (ulong dest_addr)
{
mem_malloc_start = dest_addr;
mem_malloc_end = dest_addr + CFG_MALLOC_LEN;
mem_malloc_brk = mem_malloc_start;
memset ((void *) mem_malloc_start, 0,
mem_malloc_end - mem_malloc_start);
}
接着继续回到start_armboot()，
#if (CONFIG_COMMANDS & CFG_CMD_NAND)
puts ("NAND:");
nand_init(); /* go init the NAND */
#endif
从下面可以看到，u-boot-1.1.4\include\configs\smdk2410.h中没有定义CFG_CMD_NAND，所以这段也跳过
#define CONFIG_COMMANDS \
(CONFIG_CMD_DFL | \
CFG_CMD_CACHE | \
/*CFG_CMD_NAND |*/ \
/*CFG_CMD_EEPROM |*/ \
/*CFG_CMD_I2C |*/ \
/*CFG_CMD_USB |*/ \
CFG_CMD_REGINFO | \
CFG_CMD_DATE | \
CFG_CMD_ELF)
#ifdef CONFIG_HAS_DATAFLASH /*没有被定义*/
AT91F_DataflashInit();
dataflash_print_info();
#endif
/* initialize environment */
env_relocate ();
看看这个env_relocate：
void env_relocate (void)
{
DECLARE_GLOBAL_DATA_PTR;
/*----------------------（开始）实际上这里没有被定义--------------------------*/
DEBUGF ("%s[%d] offset = 0x%lx\n", __FUNCTION__,__LINE__,
gd->reloc_off);
/*----------------------（结束）实际上这里没有被定义--------------------------*/
#ifdef CONFIG_AMIGAONEG3SE /*这个宏没有被定义*/
enable_nvram();
#endif
#ifdef ENV_IS_EMBEDDED /*这个应该是没有被定义*/
/*
* The environment buffer is embedded with the text segment,
* just relocate the environment pointer
*/
env_ptr = (env_t *)((ulong)env_ptr + gd->reloc_off);
DEBUGF ("%s[%d] embedded ENV at %p\n", __FUNCTION__,__LINE__,env_ptr);
#else
/*
* We must allocate a buffer for the environment
*/
env_ptr = (env_t *)malloc (CFG_ENV_SIZE); /*CFG_ENV_SIZE在configs\smdk2410.h中定义64k*/
DEBUGF ("%s[%d] malloced ENV at %p\n", __FUNCTION__,__LINE__,env_ptr);
#endif
/*
* After relocation to RAM, we can always use the "memory" functions
*/
env_get_char = env_get_char_memory;
if (gd->env_valid == 0) {
#if defined(CONFIG_GTH) || defined(CFG_ENV_IS_NOWHERE) /* Environment not changable */ /* 这两个宏都没有被定义*/
puts ("Using default environment\n\n");
#else
puts ("*** Warning - bad CRC, using default environment\n\n"); /*所以当env_valid为0的时候，打印校验出错信息*/
SHOW_BOOT_PROGRESS (-1); /*这个函数被定义为空*/
#endif
if (sizeof(default_environment) > ENV_SIZE)
{
puts ("*** Error - default environment is too large\n\n");
return;
}
memset (env_ptr, 0, sizeof(env_t));
memcpy (env_ptr->data, /*使用默认的环境变量参数*/
default_environment,
sizeof(default_environment));
#ifdef CFG_REDUNDAND_ENVIRONMENT /*冗余校验*/
env_ptr->flags = 0xFF;
#endif
env_crc_update (); /*取得CRC校验结果*/
gd->env_valid = 1; /*env_valid定义了为1，所以第二次启动的时候就不会出现bad crc了*/
}
else {
env_relocate_spec ();
}
gd->env_addr = (ulong)&(env_ptr->data); /*设置gd所指向的gd_t结构体类型的成员env_addr*/
#ifdef CONFIG_AMIGAONEG3SE
disable_nvram();
#endif
}
env_ptr = (env_t *)malloc (CFG_ENV_SIZE);这里有个env_t，它在include\environment.h中定义：
typedef struct environment_s {
unsigned long crc; /* CRC32 over data bytes */
#ifdef CFG_REDUNDAND_ENVIRONMENT /*smdk2410中没有定义*/
unsigned char flags; /* active/obsolete flags */
#endif
unsigned char data[ENV_SIZE]; /* Environment data */
} env_t;
#define ENV_SIZE (CFG_ENV_SIZE - ENV_HEADER_SIZE)
#define CFG_ENV_SIZE 0x10000 /* Total Size of Environment Sector */
# define ENV_HEADER_SIZE (sizeof(unsigned long))
所以ENV_SIZE=64k-(sizeof(unsigned long))
uchar env_get_char_memory (int index)
{
DECLARE_GLOBAL_DATA_PTR;
if (gd->env_valid) {
return ( *((uchar *)(gd->env_addr + index)) );
} else {
return ( default_environment[index] );
}
}
void env_crc_update (void)
{
env_ptr->crc = crc32(0, env_ptr->data, ENV_SIZE);
}
void env_relocate_spec (void)
{
#if !defined(ENV_IS_EMBEDDED) || defined(CFG_ENV_ADDR_REDUND)
#ifdef CFG_ENV_ADDR_REDUND /*在smdk2410中应该是没有被定义*/
DECLARE_GLOBAL_DATA_PTR;
if (gd->env_addr != (ulong)&(flash_addr->data)) {
env_t * etmp = flash_addr;
ulong ltmp = end_addr;
flash_addr = flash_addr_new;
flash_addr_new = etmp;
end_addr = end_addr_new;
end_addr_new = ltmp;
}
if (flash_addr_new->flags != OBSOLETE_FLAG &&
crc32(0, flash_addr_new->data, ENV_SIZE) ==
flash_addr_new->crc) {
char flag = OBSOLETE_FLAG;
gd->env_valid = 2;
flash_sect_protect (0, (ulong)flash_addr_new, end_addr_new);
flash_write(&flag,
(ulong)&(flash_addr_new->flags),
sizeof(flash_addr_new->flags));
flash_sect_protect (1, (ulong)flash_addr_new, end_addr_new);
}
if (flash_addr->flags != ACTIVE_FLAG &&
(flash_addr->flags & ACTIVE_FLAG) == ACTIVE_FLAG) {
char flag = ACTIVE_FLAG;
gd->env_valid = 2;
flash_sect_protect (0, (ulong)flash_addr, end_addr);
flash_write(&flag,
(ulong)&(flash_addr->flags),
sizeof(flash_addr->flags));
flash_sect_protect (1, (ulong)flash_addr, end_addr);
}
if (gd->env_valid == 2)
puts ("*** Warning - some problems detected "
"reading environment; recovered successfully\n\n");
#endif /* CFG_ENV_ADDR_REDUND */
memcpy (env_ptr, (void*)flash_addr, CFG_ENV_SIZE); /*这个函数相当于只实行了这一行，就是把env的存放地址赋给指针env_ptr*/
#endif /* ! ENV_IS_EMBEDDED || CFG_ENV_ADDR_REDUND */
}
这里flash_addr其实就是CFG_ENV_ADDR，也就是在0x0F0000处.
static env_t *flash_addr = (env_t *)CFG_ENV_ADDR;
#define CFG_ENV_ADDR (CFG_FLASH_BASE + 0x0F0000) /* addr of environment */
到这里为止，我们了解了env操作的流程大概是这样的，第一次启动是分配一段内存来存放env的信息，然后把内存的指针赋给env_ptr，第二次启动的时候就把存放在flash上的env的地址赋给了env_ptr.
继续回到start_armboot()中：
#ifdef CONFIG_VFD
/* must do this after the framebuffer is allocated */
drv_vfd_init();
#endif /* CONFIG_VFD */
/* IP Address */
gd->bd->bi_ip_addr = getenv_IPaddr ("ipaddr"); /*取得env中的ipaddr环境变量的值*/
/* MAC Address */
{
int i;
ulong reg;
char *s, *e;
uchar tmp[64];
i = getenv_r ("ethaddr", tmp, sizeof (tmp));
s = (i > 0) ? tmp : NULL;
for (reg = 0; reg < 6; ++reg) {
gd->bd->bi_enetaddr[reg] = s ? simple_strtoul (s, &e, 16) : 0;
if (s)
s = (*e) ? e + 1 : e;
}
}
这里有几层调用，
IPaddr_t getenv_IPaddr (char *var)
{
return (string_to_ip(getenv(var))); /*getenv和之前的getenv_r作用类似，看起来有点晕.*/
}
IPaddr_t string_to_ip(char *s)
{
IPaddr_t addr;
char *e;
int i;
if (s == NULL)
return(0);
for (addr=0, i=0; i<4; ++i) {
ulong val = s ? simple_strtoul(s, &e, 10) : 0;
addr <<= 8;
addr |= (val & 0xFF);
if (s) {
s = (*e) ? e+1 : e;
}
}
return (htonl(addr));
}
继续分析start_armboot()，
int devices_init (void)
{
#ifndef CONFIG_ARM /* already relocated for current ARM implementation */
DECLARE_GLOBAL_DATA_PTR;
ulong relocation_offset = gd->reloc_off; /*reloc_off没有定义过，默认应该为0*/
int i;
/* relocate device name pointers */
for (i = 0; i < (sizeof (stdio_names) / sizeof (char *)); ++i) {
stdio_names[i] = (char *) (((ulong) stdio_names[i]) +
relocation_offset);
}
#endif
/* Initialize the list */
devlist = ListCreate (sizeof (device_t));
if (devlist == NULL) {
eputs ("Cannot initialize the list of devices!\n");
return -1;
}
/*----------------------（开始）这里的宏都没有定义-----------------*/
#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);
#endif
#ifdef CONFIG_LCD
drv_lcd_init ();
#endif
#if defined(CONFIG_VIDEO) || defined(CONFIG_CFB_CONSOLE)
drv_video_init ();
#endif
#ifdef CONFIG_KEYBOARD
drv_keyboard_init ();
#endif
#ifdef CONFIG_LOGBUFFER
drv_logbuff_init ();
#endif
/*----------------------（结束）这里的宏都没有定义-----------------*/
drv_system_init ();
/*----------------------（开始）这里的宏都没有定义-----------------*/
#ifdef CONFIG_SERIAL_MULTI
serial_devices_init ();
#endif
#ifdef CONFIG_USB_TTY
drv_usbtty_init ();
#endif
#ifdef CONFIG_NETCONSOLE
drv_nc_init ();
#endif
/*----------------------（结束）这里的宏都没有定义-----------------*/
return (0);
}
下面列出这里会调用到的结构体和函数：
/* Device information */
typedef struct {
int flags; /* Device flags: input/output/system */
int ext; /* Supported extensions */
char name[16]; /* Device name */
list_t ListCreate (int elementSize)
{
list_t list;
list = (list_t) (NewHandle (sizeof (ListStruct))); /* create empty list */
if (list) {
(*list)->signature = LIST_SIGNATURE;
(*list)->numItems = 0;
(*list)->listSize = 0;
(*list)->itemSize = elementSize;
(*list)->percentIncrease = kDefaultAllocationPercentIncrease; /*kDefaultAllocationPercentIncrease=10*/
(*list)->minNumItemsIncrease =
kDefaultAllocationminNumItemsIncrease; /*kDefaultAllocationminNumItemsIncrease=4*/
}
return list;
}
/********************************************************************/
Handle NewHandle (unsigned int numBytes)
{
void *memPtr;
HandleRecord *hanPtr;
memPtr = calloc (numBytes, 1);
hanPtr = (HandleRecord *) calloc (sizeof (HandleRecord), 1);
if (hanPtr && (memPtr || numBytes == 0)) {
hanPtr->ptr = memPtr;
hanPtr->size = numBytes;
return (Handle) hanPtr;
} else {
free (memPtr);
free (hanPtr);
return NULL;
}
}
/********************************************************************/
typedef struct ListStructTag
{
int signature; /* debugging aid */
int percentIncrease; /* %of current size to increase by when list is out of space */
int minNumItemsIncrease; /* fixed number of items to increase by when list is out of space */
int listSize; /* number of items than can fit in the currently allocated memory */
int itemSize; /* the size of each item in the list (same for every item) */
int numItems; /* number of items currently in the list */
unsigned char itemList[1]; /* resizable array of list elements */
} ListStruct;
/*==================start_armboot()====================*/
#ifdef CONFIG_CMC_PU2 /*没有被定义*/
load_sernum_ethaddr ();
#endif /* CONFIG_CMC_PU2 */
jumptable_init ();
void jumptable_init (void) /*网上查到说做登记函数地址用，似乎没有什么用*/
{
DECLARE_GLOBAL_DATA_PTR;
int i;
gd->jt = (void **) malloc (XF_MAX * sizeof (void *));
for (i = 0; i < XF_MAX; i++)
gd->jt[i] = (void *) dummy;
gd->jt[XF_get_version] = (void *) get_version;
gd->jt[XF_malloc] = (void *) malloc;
gd->jt[XF_free] = (void *) free;
gd->jt[XF_get_timer] = (void *)get_timer;
gd->jt[XF_udelay] = (void *)udelay;
#if defined(CONFIG_I386) || defined(CONFIG_PPC)
gd->jt[XF_install_hdlr] = (void *) irq_install_handler;
gd->jt[XF_free_hdlr] = (void *) irq_free_handler;
#endif /* I386 || PPC */
#if (CONFIG_COMMANDS & CFG_CMD_I2C)
gd->jt[XF_i2c_write] = (void *) i2c_write;
gd->jt[XF_i2c_read] = (void *) i2c_read;
#endif /* CFG_CMD_I2C */
}
/*==================start_armboot()====================*/
console_init_r (); /* fully init console as a device */
/* Called after the relocation - use desired console functions */
int console_init_r (void)
{
DECLARE_GLOBAL_DATA_PTR;
device_t *inputdev = NULL, *outputdev = NULL;
int i, items = ListNumItems (devlist);
/*---------------------（开始）没有被定义------------------------------*/
#ifdef CONFIG_SPLASH_SCREEN
/* suppress all output if splash screen is enabled and we have
a bmp to display */
if (getenv("splashimage") != NULL)
outputdev = search_device (DEV_FLAGS_OUTPUT, "nulldev");
#endif
#ifdef CONFIG_SILENT_CONSOLE
/* Suppress all output if "silent" mode requested */
if (gd->flags & GD_FLG_SILENT)
outputdev = search_device (DEV_FLAGS_OUTPUT, "nulldev");
#endif
/*---------------------（结束）没有被定义------------------------------*/
/* Scan devices looking for input and output devices */
for (i = 1;
(i <= items) && ((inputdev == NULL) || (outputdev == NULL));
i++
) {
device_t *dev = ListGetPtrToItem (devlist, i);
if ((dev->flags & DEV_FLAGS_INPUT) && (inputdev == NULL)) {
inputdev = dev;
}
if ((dev->flags & DEV_FLAGS_OUTPUT) && (outputdev == NULL)) {
outputdev = dev;
}
}
/* Initializes output console first */
if (outputdev != NULL) {
console_setfile (stdout, outputdev);
console_setfile (stderr, outputdev);
}
/* Initializes input console */
if (inputdev != NULL) {
console_setfile (stdin, inputdev);
}
gd->flags |= GD_FLG_DEVINIT; /* device initialization completed */
/*---------------------（开始）没有被定义------------------------------*/
#ifndef CFG_CONSOLE_INFO_QUIET
/* Print information */
puts ("In: ");
if (stdio_devices[stdin] == NULL) {
puts ("No input devices available!\n");
} else {
printf ("%s\n", stdio_devices[stdin]->name);
}
puts ("Out: ");
if (stdio_devices[stdout] == NULL) {
puts ("No output devices available!\n");
} else {
printf ("%s\n", stdio_devices[stdout]->name);
}
puts ("Err: ");
if (stdio_devices[stderr] == NULL) {
puts ("No error devices available!\n");
} else {
printf ("%s\n", stdio_devices[stderr]->name);
}
#endif /* CFG_CONSOLE_INFO_QUIET */
/*---------------------（结束）没有被定义------------------------------*/
/* Setting environment variables */
for (i = 0; i < 3; i++) {
setenv (stdio_names[i], stdio_devices[i]->name);
}
#if 0
/* If nothing usable installed, use only the initial console */
if ((stdio_devices[stdin] == NULL) && (stdio_devices[stdout] == NULL))
return (0);
#endif
return (0);
}
/****************************下面这段是从网上摘抄下来的*************************/
console_init_r ();后期控制台初始化
主要过程：查看环境参数stdin,stdout,stderr中对标准IO的指定的设备名称，再按照环境指定的名称搜索devlist，将搜到的设备指针赋给标准IO数组stdio_devices[]。置gd->flag标志GD_FLG_DEVINIT。这个标志影响putc，getc函数的实现，未定义此标志时直接由串口serial_getc和serial_putc实现，定义以后通过标准设备数组stdio_devices[]中的putc和getc来实现IO。
下面是相关代码：
void putc (const char c)
{
#ifdef CONFIG_SILENT_CONSOLE
if (gd->flags & GD_FLG_SILENT)//GD_FLG_SILENT无输出标志
return;
#endif
if (gd->flags & GD_FLG_DEVINIT) {//设备list已经初始化
/* Send to the standard output */
fputc (stdout, c);
} else {
/* Send directly to the handler */
serial_putc (c);//未初始化时直接从串口输出。
}
}
void fputc (int file, const char c)
{
if (file < MAX_FILES)
stdio_devices[file]->putc (c);
}
为什么要使用devlist，std_device[]？
为了更灵活地实现标准IO重定向，任何可以作为标准IO的设备，如USB键盘，LCD屏，串口等都可以对应一个device_t的结构体变量，只需要实现getc和putc等函数，就能加入到devlist列表中去，也就可以被assign为标准IO设备std_device中去。如函数
int console_assign (int file, char *devname); /* Assign the console 重定向标准输入输出*/
这个函数功能就是把名为devname的设备重定向为标准IO文件file(stdin,stdout,stderr)。其执行过程是在devlist中查找devname的设备，返回这个设备的device_t指针，并把指针值赋给std_device[file]。
/****************************上面这段是从网上摘抄下来的*************************/
/*==================start_armboot()====================*/
#if defined(CONFIG_MISC_INIT_R) /*没有被定义*/
/* miscellaneous platform dependent initialisations */
misc_init_r ();
#endif
/* enable exceptions */
enable_interrupts ();
#ifdef CONFIG_USE_IRQ /*CONFIG_USE_IRQ没有被定义，所以这段跳过*/
/* enable IRQ interrupts */
void enable_interrupts (void)
{
unsigned long temp;
__asm__ __volatile__("mrs %0, cpsr\n"
"bic %0, %0, #0x80\n"
"msr cpsr_c, %0"
: "=r" (temp)
:
: "memory");
}
/*==================start_armboot()====================*/
/* Perform network card initialisation if necessary */
#ifdef CONFIG_DRIVER_CS8900
cs8900_get_enetaddr (gd->bd->bi_enetaddr);
#endif
网络部分不懂，暂时不看，等看完cs8900的datasheet再看
void cs8900_get_enetaddr (uchar * addr)
{
int i;
unsigned char env_enetaddr[6];
char *tmp = getenv ("ethaddr");
char *end;
for (i=0; i<6; i++) {
env_enetaddr[i] = tmp ? simple_strtoul(tmp, &end, 16) : 0;
if (tmp)
tmp = (*end) ? end+1 : end;
}
/* verify chip id */
if (get_reg_init_bus (PP_ChipID) != 0x630e)
return;
eth_reset ();
if ((get_reg (PP_SelfST) & (PP_SelfSTAT_EEPROM | PP_SelfSTAT_EEPROM_OK)) ==
(PP_SelfSTAT_EEPROM | PP_SelfSTAT_EEPROM_OK)) {
/* Load the MAC from EEPROM */
for (i = 0; i < 6 / 2; i++) {
unsigned int Addr;
Addr = get_reg (PP_IA + i * 2);
addr[i * 2] = Addr & 0xFF;
addr[i * 2 + 1] = Addr >> 8;
}
if (memcmp(env_enetaddr, "\0\0\0\0\0\0", 6) != 0 &&
memcmp(env_enetaddr, addr, 6) != 0) {
printf ("\nWarning: MAC addresses don't match:\n");
printf ("\tHW MAC address: "
"%02X:%02X:%02X:%02X:%02X:%02X\n",
addr[0], addr[1],
addr[2], addr[3],
addr[4], addr[5] );
printf ("\t\"ethaddr\" value: "
"%02X:%02X:%02X:%02X:%02X:%02X\n",
env_enetaddr[0], env_enetaddr[1],
env_enetaddr[2], env_enetaddr[3],
env_enetaddr[4], env_enetaddr[5]) ;
debug ("### Set MAC addr from environment\n");
memcpy (addr, env_enetaddr, 6);
}
if (!tmp) {
char ethaddr[20];
sprintf (ethaddr, "%02X:%02X:%02X:%02X:%02X:%02X",
addr[0], addr[1],
addr[2], addr[3],
addr[4], addr[5]) ;
debug ("### Set environment from HW MAC addr = \"%s\"\n", ethaddr);
setenv ("ethaddr", ethaddr);
}
}
}
/*--------------------------这些似乎都没有用到-----------------------*/
#if defined(CONFIG_DRIVER_SMC91111) || defined (CONFIG_DRIVER_LAN91C96)
if (getenv ("ethaddr")) {
smc_set_mac_addr(gd->bd->bi_enetaddr);
}
#endif /* CONFIG_DRIVER_SMC91111 || CONFIG_DRIVER_LAN91C96 */
/* Initialize from environment */
if ((s = getenv ("loadaddr")) != NULL) {
load_addr = simple_strtoul (s, NULL, 16);
}
#if (CONFIG_COMMANDS & CFG_CMD_NET)
if ((s = getenv ("bootfile")) != NULL) {
copy_filename (BootFile, s, sizeof (BootFile));
}
#endif /* CFG_CMD_NET */
#ifdef BOARD_LATE_INIT
board_late_init ();
#endif
/*--------------------------这些似乎都没有用到-----------------------*/
#if (CONFIG_COMMANDS & CFG_CMD_NET)
#if defined(CONFIG_NET_MULTI) /*CONFIG_NET_MULTI有被间接定义到*/
puts ("Net: ");
#endif
eth_initialize(gd->bd);
eth_initialize()有两个，第二个没有被编译，只用到第一个
#if (CONFIG_COMMANDS & CFG_CMD_NET) && defined(CONFIG_NET_MULTI)
int eth_initialize(bd_t *bis)
#elif (CONFIG_COMMANDS & CFG_CMD_NET) && !defined(CONFIG_NET_MULTI)
int eth_initialize(bd_t *bis)
终于到main_loop了，真是开心
/* main_loop() can return to retry autoboot, if so just run it again. */
for (;;) {
main_loop ();
}
/* NOTREACHED - no way out of command loop except booting */
}
这个函数也非常长，这里讲有效代码贴出来：
void main_loop (void)
{
#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)
char *s;
int bootdelay;
#endif
#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)
s = getenv ("bootdelay");
bootdelay = s ? (int)simple_strtol(s, NULL, 10) : CONFIG_BOOTDELAY;
debug ("### main_loop entered: bootdelay=%d\n\n", bootdelay);
s = getenv ("bootcmd");
debug ("### main_loop: bootcmd=\"%s\"\n", s ? s : "");
if (bootdelay >= 0 && s && !abortboot (bootdelay)) {
parse_string_outer(s, FLAG_PARSE_SEMICOLON |
FLAG_EXIT_FROM_LOOP);
}
#endif /* CONFIG_BOOTDELAY */
/*
* Main Loop for Monitor Command Processing
*/
#ifdef CFG_HUSH_PARSER
parse_file_outer();
/* This point is never reached */
for (;;);
#else
for (;;) {
#ifdef CONFIG_BOOT_RETRY_TIME
if (rc >= 0) {
/* Saw enough of a valid command to
* restart the timeout.
*/
reset_cmd_timeout();
}
#endif
len = readline (CFG_PROMPT);
flag = 0; /* assume no special flags for now */
if (len > 0)
strcpy (lastcommand, console_buffer);
else if (len == 0)
flag |= CMD_FLAG_REPEAT;
#ifdef CONFIG_BOOT_RETRY_TIME
else if (len == -2) {
/* -2 means timed out, retry autoboot
*/
puts ("\nTimed out waiting for command\n");
# ifdef CONFIG_RESET_TO_RETRY
/* Reinit board to run initialization code again */
do_reset (NULL, 0, 0, NULL);
# else
return; /* retry autoboot */
# endif
}
#endif
if (len == -1)
puts ("\n");
else
rc = run_command (lastcommand, flag);
if (rc <= 0) {
/* invalid command or not repeatable, forget it */
lastcommand[0] = 0;
}
}
#endif /*CFG_HUSH_PARSER*/
}
