标签：watchdog || tran put text ogre finally 寄存器 via
uboot启动代码流程
board.c文件__attribute__((nomips16)) void board_init_r (gd_t *id, ulong dest_addr)函数
1、调用do_bootm
if(BootType == ‘3‘) {
char *argv[2];
sprintf(addr_str, "0x%X", CFG_KERN_ADDR);
argv[1] = &addr_str[0];
printf(" \n3: System Boot system code via Flash.\n");
do_bootm(cmdtp, 0, 2, argv);
}
board.c文件__attribute__((nomips16)) void board_init_f(ulong bootflag)
1、初始化RT2880 SOC
给寄存器赋值，初始化。
2、初始化gd结构体
/* Pointer is writable since we allocated a register for it.
*/
gd = &gd_data;
/* compiler optimization barrier needed for GCC >= 3.4 */
__asm__ __volatile__("": : :"memory");
memset ((void *)gd, 0, sizeof (gd_t));
3、执行init_fnc_ptr函数指针数组中的各个初始化函数
#if 0
for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
if ((*init_fnc_ptr)() != 0) {
hang ();
}
}
#endif
MTK把它屏蔽拆出来
#if defined (RT6855A_ASIC_BOARD) || defined(RT6855A_FPGA_BOARD)
watchdog_reset();
#endif
timer_init();
env_init(); /* initialize environment */
init_baudrate(); /* initialze baudrate settings */
serial_init(); /* serial communications setup */
console_init_f();
display_banner(); /* say that we are here */
checkboard();
init_func_ram();
4、给寄存器赋值
/* reset Frame engine */
value = le32_to_cpu(*(volatile u_long *)(RALINK_SYSCTL_BASE + 0x0034));
*(volatile u_long *)(RALINK_SYSCTL_BASE + 0x0034) = cpu_to_le32(value);
5、分配DRAM有顶部到底部
/*
* Now that we have DRAM mapped and working, we can
* relocate the code and continue running from DRAM.
*/
得到内存大小
addr = CFG_SDRAM_BASE + gd->ram_size;
预留4K内存
/* round down to next 4 kB limit.
*/
addr &= ~(4096 - 1);
#ifdef DEBUG
debug ("Top of RAM usable for U-Boot at: %08lx\n", addr);
#endif
分配16k内存给U-boot代码，数据段，BSS段
/* Reserve memory for U-Boot code, data & bss
* round down to next 16 kB limit
*/
addr -= len;
addr &= ~(16 * 1024 - 1);
#ifdef DEBUG
debug ("Reserving %ldk for U-Boot at: %08lx\n", len >> 10, addr);
#endif
分配堆空间
/* Reserve memory for malloc() arena.
*/
addr_sp = addr - TOTAL_MALLOC_LEN;
#ifdef DEBUG
debug ("Reserving %dk for malloc() at: %08lx\n",
TOTAL_MALLOC_LEN >> 10, addr_sp);
#endif
分配board info空间，参数空间，gd（global data）
/*
* (permanently) allocate a Board Info struct
* and a permanent copy of the "global" data
*/
addr_sp -= sizeof(bd_t);
bd = (bd_t *)addr_sp;
gd->bd = bd;
#ifdef DEBUG
debug ("Reserving %d Bytes for Board Info at: %08lx\n",
sizeof(bd_t), addr_sp);
#endif
addr_sp -= sizeof(gd_t);
id = (gd_t *)addr_sp;
#ifdef DEBUG
debug ("Reserving %d Bytes for Global Data at: %08lx\n",
sizeof (gd_t), addr_sp);
#endif
/* Reserve memory for boot params.
*/
addr_sp -= CFG_BOOTPARAMS_LEN;
bd->bi_boot_params = addr_sp;
#ifdef DEBUG
debug ("Reserving %dk for boot params() at: %08lx\n",
CFG_BOOTPARAMS_LEN >> 10, addr_sp);
#endif
分配栈空间，预留16K隔离区，剩下的都是
/*
* Finally, we set up a new (bigger) stack.
*
* Leave some safety gap for SP, force alignment on 16 byte boundary
* Clear initial stack frame
*/
addr_sp -= 16;
addr_sp &= ~0xF;
s = (ulong *)addr_sp;
*s-- = 0;
*s-- = 0;
addr_sp = (ulong)s;
#ifdef DEBUG
debug ("Stack Pointer at: %08lx\n", addr_sp);
#endif
拷贝代码到栈空间
/* On the purple board we copy the code in a special way
* in order to solve flash problems
*/
#ifdef CONFIG_PURPLE
copy_code(addr);
#endif
调用内存分配函数
relocate_code (addr_sp, id, /*TEXT_BASE*/ addr);
=================================================
cmd_bootm.c文件do_bootm函数
int do_bootm (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
1、得到image的起始地址
printf ("## Booting image at %08lx ...\n", addr);
2、读取image头
raspi_read(&header, (char *)(addr - CFG_FLASH_BASE), sizeof(image_header_t));
3、校验image头是否正确
image头结构体
typedef struct image_header {
uint32_t ih_magic; /* Image Header Magic Number */
uint32_t ih_hcrc; /* Image Header CRC Checksum */
uint32_t ih_time; /* Image Creation Timestamp */
uint32_t ih_size; /* Image Data Size */
uint32_t ih_load; /* Data Load Address */
uint32_t ih_ep; /* Entry Point Address */
uint32_t ih_dcrc; /* Image Data CRC Checksum */
uint8_t ih_os; /* Operating System */
uint8_t ih_arch; /* CPU architecture */
uint8_t ih_type; /* Image Type */
uint8_t ih_comp; /* Compression Type */
uint8_t ih_name[IH_NMLEN]; /* Image Name */
} image_header_t;
校验image头代码
checksum = ntohl(hdr->ih_hcrc);
hdr->ih_hcrc = 0;
if (crc32 (0, (char *)data, len) != checksum) {
puts ("Bad Header Checksum\n");
SHOW_BOOT_PROGRESS (-2);
return 1;
}
print_image_hdr ((image_header_t *)hdr);
4、根据image头部信息读取image（去不同型号的FLASH读取）
#ifdef CONFIG_HAS_DATAFLASH
if (addr_dataflash(addr)){
read_dataflash(data, len, (char *)CFG_LOAD_ADDR);
data = CFG_LOAD_ADDR;
}
#endif
#if defined (CFG_ENV_IS_IN_NAND)
if (addr >= CFG_FLASH_BASE) {
ulong load_addr = CFG_SPINAND_LOAD_ADDR;
ranand_read(load_addr, data - CFG_FLASH_BASE, len);
data = load_addr;
}
#elif defined (CFG_ENV_IS_IN_SPI)
if (addr >= CFG_FLASH_BASE) {
ulong load_addr = CFG_SPINAND_LOAD_ADDR;
raspi_read(load_addr, data - CFG_FLASH_BASE, len);
data = load_addr;
}
#else //CFG_ENV_IS_IN_FLASH
#endif
5、校验image是否正确
if (verify) {
puts (" Verifying Checksum ... ");
if (crc32 (0, (char *)data, len) != ntohl(hdr->ih_dcrc)) {
printf ("Bad Data CRC\n");
SHOW_BOOT_PROGRESS (-3);
return 1;
}
puts ("OK\n");
}
6、检测是否支持该芯片型号、镜像类型、是否压缩（ih_arch、ih_type、ih_comp）
if (hdr->ih_arch != IH_CPU_NIOS2)
#else
# error Unknown CPU type
#endif
{
printf ("Unsupported Architecture 0x%x\n", hdr->ih_arch);
SHOW_BOOT_PROGRESS (-4);
return 1;
}
7、将控制权交给内核
#ifdef DEBUG
printf ("## Transferring control to Linux (at address %08lx) ...\n",
(ulong) theKernel);
#endif
标签：watchdog || tran put text ogre finally 寄存器 via
原文地址：https://www.cnblogs.com/EA-Coke/p/13601900.html
