uboot第二阶段代码.doc

/* * (C) Copyright 2002-2006 * Wolfgang Denk, DENX Software Engineering, wddenx.de. * * (C) Copyright 2002 * Sysgo Real-Time Solutions, GmbH * Marius Groeger * * See file CREDITS for list of people who contributed to this * project. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA */* * To match the U-Boot user interface on ARM platforms to the U-Boot * standard (as on PPC platforms), some messages with debug character * are removed from the default U-Boot build. * * Define DEBUG here if you want additional info as shown below * printed upon startup: * * U-Boot code: 00F00000 - 00F3C774 BSS: - 00FC3274 * IRQ Stack: 00ebff7c * FIQ Stack: 00ebef7c */#include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_BITBANGMII#include #endif#ifdef CONFIG_DRIVER_SMC91111#include ./drivers/net/smc91111.h#endif#ifdef CONFIG_DRIVER_LAN91C96#include ./drivers/net/lan91c96.h#endifDECLARE_GLOBAL_DATA_PTR;ulong monitor_flash_len;#ifdef CONFIG_HAS_DATAFLASHextern int AT91F_DataflashInit(void);extern void dataflash_print_info(void);#endif#ifndef CONFIG_IDENT_STRING#define CONFIG_IDENT_STRING #endifconst char version_string =U_BOOT_VERSION ( U_BOOT_DATE - U_BOOT_TIME )CONFIG_IDENT_STRING;#ifdef CONFIG_DRIVER_RTL8019extern void rtl8019_get_enetaddr (uchar * addr);#endif#if defined(CONFIG_HARD_I2C) | defined(CONFIG_SOFT_I2C)#include #endif/* * Coloured LED functionality * * May be supplied by boards if desired */void inline _coloured_LED_init (void) void coloured_LED_init (void) _attribute_(weak, alias(_coloured_LED_init);void inline _red_LED_on (void) void red_LED_on (void) _attribute_(weak, alias(_red_LED_on);void inline _red_LED_off(void) void red_LED_off(void) _attribute_(weak, alias(_red_LED_off);void inline _green_LED_on(void) void green_LED_on(void) _attribute_(weak, alias(_green_LED_on);void inline _green_LED_off(void) void green_LED_off(void) _attribute_(weak, alias(_green_LED_off);void inline _yellow_LED_on(void) void yellow_LED_on(void) _attribute_(weak, alias(_yellow_LED_on);void inline _yellow_LED_off(void) void yellow_LED_off(void) _attribute_(weak, alias(_yellow_LED_off);void inline _blue_LED_on(void) void blue_LED_on(void) _attribute_(weak, alias(_blue_LED_on);void inline _blue_LED_off(void) void blue_LED_off(void) _attribute_(weak, alias(_blue_LED_off);/* * Init Utilities* * * Some of this code should be moved into the core functions, * or dropped completely, * but lets get it working (again) first. */#if defined(CONFIG_ARM_DCC) & !defined(CONFIG_BAUDRATE)#define CONFIG_BAUDRATE 115200#endifstatic int init_baudrate (void)char tmp64;/* 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);static int display_banner (void)printf (nn%snn, version_string);debug (U-Boot code: %08lX - %08lX BSS: - %08lXn, _armboot_start, _bss_start, _bss_end);#ifdef CONFIG_MODEM_SUPPORTdebug (Modem Support enabledn);#endif#ifdef CONFIG_USE_IRQdebug (IRQ Stack: %08lxn, IRQ_STACK_START);debug (FIQ Stack: %08lxn, FIQ_STACK_START);#endifreturn (0);/* * WARNING: this code looks cleaner than the PowerPC version, but * has the disadvantage that you either get nothing, or everything. * On PowerPC, you might see DRAM: before the system hangs - which * gives a simple yet clear indication which part of the * initialization if failing. */static int display_dram_config (void)int i;#ifdef DEBUGputs (RAM Configuration:n);for(i=0; ibd-bi_drami.start);print_size (gd-bd-bi_drami.size, n);#elseulong size = 0;for (i=0; ibd-bi_drami.size;puts(DRAM: );print_size(size, n);#endifreturn (0);#ifndef CONFIG_SYS_NO_FLASHstatic void display_flash_config (ulong size)puts (Flash: );print_size (size, n);#endif /* CONFIG_SYS_NO_FLASH */#if defined(CONFIG_HARD_I2C) | defined(CONFIG_SOFT_I2C)static int init_func_i2c (void)puts (I2C: );i2c_init (CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);puts (readyn);return (0);#endif#if defined(CONFIG_CMD_PCI) | defined (CONFIG_PCI)#include static int arm_pci_init(void)pci_init();return 0;#endif /* CONFIG_CMD_PCI | CONFIG_PCI */* * Breathe some life into the board. * * Initialize a serial port as console, and carry out some hardware * tests. * * The first part of initialization is running from Flash memory; * its main purpose is to initialize the RAM so that we * can relocate the monitor code to RAM. */* * All attempts to come up with a common initialization sequence * that works for all boards and architectures failed: some of the * requirements are just _too_ different. To get rid of the resulting * mess of board dependent #ifdefed code we now make the whole * initialization sequence configurable to the user. * * The requirements for any new initalization function is simple: it * receives a pointer to the global data structure as its only * argument, and returns an integer return code, where 0 means * continue and != 0 means fatal error, hang the system. */typedef int (init_fnc_t) (void);/注意这种用法，linux内核中也经常使用 int print_cpuinfo (void);init_fnc_t *init_sequence = #if defined(CONFIG_ARCH_CPU_INIT)arch_cpu_init,/* basic arch cpu dependent setup */* basic arch cpu dependent setup /cpu/arm920t/cpu.c中定义，该函数为空，因为没有采用IRQ或FIQ模式*/ CPU的相关配置，如初始化IRQ/FIQ模式的栈cpu/arm920t/cpu.c*/#endifboard_init,/* basic board dependent setup */* basic board dependent ，初始化时钟频率，配置IO口，初始化全局数据bd（如平台号，传递内核参数的地址） ，setup /board/smdk2410/smdk2410.c */* basic board dependent setup开发板相关配置，是对板子的初始化,设置MPLL，改变系统时钟，以及一些GPIO寄存器的值，还设置了U-Boot机器码和内核启动参数地址，它是开发板相关的函数，比如2410是在：board/smdk2410/smdk2410.c中实现*/ #if defined(CONFIG_USE_IRQ)interrupt_init,/* set up exceptions 初始化中断，在cpu/arm920t/s3c24x0/interrupts.c实现*/#endiftimer_init,/* initialize timer */* initialize timer 使用定时器4 cpu/arm920t/s3c24x0/timer.c */#ifdef CONFIG_FSL_ESDHCget_clocks,#endifenv_init,/* initialize environment */* initialize environment common/Env_nand.c 校验环境变量，并获取环境变量的地址*/init_baudrate,/* initialze baudrate settings 始化波特率lib_arm/board.c */*/serial_init,/* serial communications setup */ driver/serial/serial_s3c24x0.c 初始化串口0，用于打印信息,该平台只支持配置串口1来打印信息 */console_init_f,/* stage 1 init of console */display_banner,/* say that we are here */打印uboot代码段和数据段地址信息#if defined(CONFIG_DISPLAY_CPUINFO)print_cpuinfo,/* display cpu info (and speed) */#endif#if defined(CONFIG_DISPLAY_BOARDINFO)checkboard,/* display board info */#endif#if defined(CONFIG_HARD_I2C) | defined(CONFIG_SOFT_I2C)init_func_i2c,#endifdram_init,/* configure available RAM banks */获取ram的地址和大小，banks board/sunsang/smdk2410/smdk2410.c*/#if defined(CONFIG_CMD_PCI) | defined (CONFIG_PCI)arm_pci_init,#endif/打印BANK的相关信息display_dram_config,/lib_arm/board.cNULL,;对于内核启动来说，这部分主要是完成全局数据gd的初始化，以便内核访问start_armboot是U-Boot执行的第一个C语言函数，完成系统初始化工作，进入主循环，处理用户输入的命令。这里只简要列出了主要执行的函数流程：可以看出这里定义了一个指针数组,它的每一个元素都是指针变量,这些指针变量指向的类型为init_fnc_t,在C语言中函数的入口地址就是函数名,所以这里使用一系列函数名来初始化这个数组void start_armboot (void)init_fnc_t *init_fnc_ptr;/*它是指向指针的指针变量,变量的类型为init_fnc_t,这是一个使用typedef定义的函数类型, 其中init_fnc_ptr将在后面指向一个数组指针*/char *s;#if defined(CONFIG_VFD) | defined(CONFIG_LCD)unsigned long addr;#endif gd_t: 定义在 /include/asm-arm/Global_data.h中,包含一些全局通用的变量. _armboot_start: 代码的起始地址,它定义在start.S中的前几行中,定义为 _start 当系统第一次加电时,指令是从0x0地址开始执行的,所以此时的 _start值 应为0x0;而当uboot经过代码重定位后,指令会从 _TEXT_BASE 处开始执行, 此时的 _start值就成了 _TEXT_BASE的值. CFG_MALLOC_LEN: 在/include/configs/smdk2440.h中有定义,该变量表示供 malloc函数使用的内存池空间,代码中定义值为:0x10000+128*1024 |-|- _armboot_start基址| 4 | |-|- malloc函数池基址| 3 | |-|- (gd_t)gd(全局变量表)基址| 2 | |-|= 3.4 */_asm_ _volatile_(: : :memory);memset (void*)gd, 0, sizeof (gd_t);/把gd变量的内容填充为0 ,填充 3 区的数据为0 ,即初始化gd表.注意:这里并没有/初始化bd表,在gd表中的bd成员只是一个指针,因为对初始化的是个指针地址 bd_t 结构体在/include/asm-arm/U-boot.h中定义, 定义板子的一些信息,包括: 波特率,IP地址, 以太网地址, 架构编码,启动参数 ,BANK的起始地址和大小等gd-bd = (bd_t*)(char*)gd - sizeof(bd_t);/分配区域 2 给bd, bd的基址 = gd的基址 - bd的尺寸/获取bd_info结构体指针memset (gd-bd, 0, sizeof (bd_t);/把区域 2 填充为 0 ,即初始化 bd 表gd-flags |= GD_FLG_RELOC;/标志位已经重定向monitor_flash_len = _bss_start - _armboot_start;/整个代码区的长度/_bss_start 在u-boot.lds中定位 在bin文件中 BSS 段和 TEXT 段和 DATA 段存放的顺序同前向后依次是: TEXT(代码段 RO) DATA(已初始化数据段 RW) BSS(未初始化数据段ZI) 所以 _bss_start 的基址等于 TEXT的长度加上DATA的长度.即: _bss_start(BSS段基址) = 代码段长度+数据段长度BSS(Block Started by Symbol)段是未被初始化的数据段,是存放程序中 未被初始化的全局变量的一块内存区域,初始化时应清零;该段只有 名称和大小却没有值;该段不包含任何数据,只是简单的维护开始和 结束的地址,以便内存区能在运行时被有效地清零,它在应用程序的 映像文件(ARM中也即bin文件)中并不存在. text :代码段,是包含程序代码的段dat :已经初始化的数据段,保存已经初始化的全局变量. 在嵌入式系统中,bin文件(又称Image文件)中只包含text和data段, 而bss段不在其中,它是由系统初始化为零. /_armboot_start 在start.S中定义为_start,而_start为代码的起始地址 /只包含 RO(TEXT) 和 RW(DATA) 段.重定位前的值为0x0,此时指向flash,/重定位后则指向RAM中的某一地址/由此可以知道: _bss_start - _armboot_start 的值即是在第一阶段从/flash中重定位到RAM中的那部分代码的长度,也即可TEXT和DATA数据段,/这个值与start.S中的重定位那部分代码所计算的值是相等的/所以,monitor_flash_len表示从flash中搬来的代码的长度for (init_fnc_ptr = init_sequence; *init_fnc_ptr; +init_fnc_ptr) if (*init_fnc_ptr)() != 0) hang ();/各设置的初始化.当返回值不为0时表示初始化失败 ,此时会调用 hang()函数/打印一错误提示信息,然后进入死循环/* armboot_start is defined in the board-specific linker script */mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN,CONFIG_SYS_MALLOC_LEN);#ifndef CONFIG_SYS_NO_FLASHCFG_NO_FLASH /没有flash,如果没定义该常量则表示板子上有flash,此时调用flash_init()对其进行初始化./* configure available FLASH banks */display_flash_config (flash_init ();/打印flash的信息,这里仅输出它的大小/board/smdk2410/flash.c配置flash/从其实现来看，好像只是配置nor flash/ze = flash_init (); /isplay_flash_config (size); /打印flash的信息,这里仅输出它的大小定义显示类型#endif /* CONFIG_SYS_NO_FLASH */#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);/按页对其方式保留显存vfd_setmem (addr);gd-fb_base = addr;/帧缓冲基地址#endif /* CONFIG_VFD */#ifdef CONFIG_LCD*/为LCD分配RAM(内存)空间/* board init may have inited fb_base */if (!gd-fb_base) #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);lcd_setmem (addr);gd-fb_base = addr;/为显存缓冲区地址变量赋值#endif /* CONFIG_LCD */初始化nand flash，这是在nand flash启动的s3c2410移植u-boot的关键，根据flash时序编写函数即可/在include/configs/smdk2410.h中的command definition中增加CONFIG_COMMANDS和CFG_CMD_NAND命令#if defined(CONFIG_CMD_NAND)/如果定义了命令和NAND命令,则初始化nand puts (NAND: );nand_init();/* go init the NAND */board/smdk2410/smdk2410.c，获取nand的基地址和 大小信息#endif#if defined(CONFIG_CMD_ONENAND)onenand_init();#endif#ifdef CONFIG_HAS_DATAFLASHAT91F_DataflashInit();dataflash_print_info();#endif/* initialize environment */env_relocate ();/* initialize environment 环境的初始化，代码在common/env_common.c中*/#ifdef CONFIG_VFD/* must do this after the framebuffer is allocated */drv_vfd_init();#endif /* CONFIG_VFD */#ifdef CONFIG_SERIAL_MULTIserial_initialize();#endif/* IP Address */* IP Address 为全局变量的成员赋值:IP地址*/gd-bd-bi_ip_addr = getenv_IPaddr (ipaddr);/通过命令行参数传递获取ip地址stdio_init ();/* get the devices list going. */标准输入输出和设备初始化.jumptable_init ();();/跳转表初始化，函数在commonexports.c文件中#if defined(CONFIG_API)/* Initialize API */api_init ();#endifconsole_init_r ();/* fully init console as a device */初始化串口#if defined(CONFIG_ARCH_MISC_INIT)/* miscellaneous arch dependent initialisations */arch_misc_init ();#endif#if defined(CONFIG_MISC_INIT_R)/* miscellaneous platform dependent initialisations */misc_init_r ();#endif/* enable exceptions */enable_interrupts ();/启用中断/* Perform network card initialisati