U-Boot 분석(5)

Board.C

start.s에서 start_armboot()로 제어가 넘어왔다.  이 함수는 board.c에 정의되어있다.

board.c를 보도록 하자.  board.c는 /lib_arm/에 위치해 있다.

/*
 * (C) Copyright 2002
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Marius Groeger <mgroeger@sysgo.de>
 *
 * 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
 */

#include <common.h>
#include <command.h>
#include <malloc.h>
#include <devices.h>
#include <version.h>
#include <net.h>

#ifdef CONFIG_DRIVER_SMC91111
#include "../drivers/smc91111.h"
#endif
#ifdef CONFIG_DRIVER_LAN91C96
#include "../drivers/lan91c96.h"
#endif

#if (CONFIG_COMMANDS & CFG_CMD_NAND)
void nand_init (void);
#endif

ulong monitor_flash_len;

#ifdef CONFIG_HAS_DATAFLASH
extern int  AT91F_DataflashInit(void);
extern void dataflash_print_info(void);
#endif

#ifndef CONFIG_IDENT_STRING
#define CONFIG_IDENT_STRING ""
#endif

const char version_string[] =
 U_BOOT_VERSION" (" __DATE__ " - " __TIME__ ")"CONFIG_IDENT_STRING;

#ifdef CONFIG_DRIVER_CS8900
extern void cs8900_get_enetaddr (uchar * addr);
#endif

#ifdef CONFIG_DRIVER_RTL8019
extern void rtl8019_get_enetaddr (uchar * addr);
#endif

/*
 * Begin and End of memory area for malloc(), and current "brk"
 */
static ulong mem_malloc_start = 0;
static ulong mem_malloc_end = 0;
static ulong mem_malloc_brk = 0;

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);
}

void *sbrk (ptrdiff_t increment)
{
 ulong old = mem_malloc_brk;
 ulong new = old + increment;

 if ((new < mem_malloc_start) || (new > mem_malloc_end)) {
  return (NULL);
 }
 mem_malloc_brk = new;

 return ((void *) old);
}

/************************************************************************
 * Init Utilities       *
 ************************************************************************
 * Some of this code should be moved into the core functions,
 * or dropped completely,
 * but let's get it working (again) first...
 */

 

 

/* console에 사용할 UART의 baud rate를 설정 */
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);
}

 

/* 설정된 정보를 화면에 출력한다. */
/* uboot version및 code, data, stack의 위치를 console에 출력 */
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
 puts ("Modem Support enabled\n");
#endif
#ifdef CONFIG_USE_IRQ
 printf ("IRQ Stack: %08lx\n", IRQ_STACK_START);
 printf ("FIQ Stack: %08lx\n", FIQ_STACK_START);
#endif

 return (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.
 */
 /* DRAM셋팅후 화면에 출력 */
static int display_dram_config (void)
{
 DECLARE_GLOBAL_DATA_PTR;
 int i;

 puts ("RAM Configuration:\n");

 for(i=0; i<CONFIG_NR_DRAM_BANKS; i++) {
  printf ("Bank #%d: %08lx ", i, gd->bd->bi_dram[i].start);
  print_size (gd->bd->bi_dram[i].size, "\n");
 }

 return (0);
}

static void display_flash_config (ulong size)
{
 puts ("Flash: ");
 print_size (size, "\n");
}

/*
 * 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 #ifdef'ed 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 it's 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);

/* 포인터 변수는 값으로 주소를 갖는다. 각 주소에 가보면 함수가 존재할것이다. */
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 UART 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, /* SDRAM start address, size를 console에 출력 */
#if defined(CONFIG_VCMA9)
 checkboard,
#endif
 NULL,
};

 

 

/* board와 관련된 모든 자원을 초기화 */
void start_armboot (void)
{
 /* Global_data.h에 명시  register volatile gd_t *gd asm("r8") */
 DECLARE_GLOBAL_DATA_PTR; 

 ulong size;
 init_fnc_t **init_fnc_ptr; /* 2차원 함수 배열. init_fnc_t *형은 *init_fnc_ptr의 데이터를 갖는다. 이는 어떠한 함수를 가리킬 것이고 이 함수들은 바로 위에 정의되어 있다. */
 char *s;
/* LCD controller설정 */
#if defined(CONFIG_VFD) || defined(CONFIG_LCD)
 unsigned long addr;
#endif

 /* 포인터 설정 */
 /* Pointer is writable since we allocated a register for it */
 gd = (gd_t*)(_armboot_start - CFG_MALLOC_LEN - sizeof(gd_t));
 /* compiler optimization barrier needed for GCC >= 3.4 */
 __asm__ __volatile__("": : :"memory");

 

 /* 메모리 클리어.  이 함수가 정의된 부분으로 가보면 gd부터 sizeof로 구한 영역만큼 0의 값을 넣어주는 함수이다. */
 memset ((void*)gd, 0, sizeof (gd_t));
 gd->bd = (bd_t*)((char*)gd - sizeof(bd_t));

 /* global_data struct의 data를 0으로 초기화 한다. */
 /* gd->bd가리키는 영역을 gd_t크기만큼 0으로 만든다. */
 memset (gd->bd, 0, sizeof (bd_t)); 

 

 /* 모니터코드의 flash에서의 길이를 구한다. */
 monitor_flash_len = _bss_start - _armboot_start;

 

 /* board에 관련된 모든 자원을 초기화 한다. 바로 위의 함수배열로 정의되어 있다. 각각의 함수를 찾아보면서 어떤 동작을 하는지 알아보시길...  */
 /* cpu, board, interrupt, env, baudrate, serial, console, display, dram등등.. */
 for (init_fnc_ptr = init_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
  if ((*init_fnc_ptr)() != 0) {
   /* error가 발생햇으니 reset하라고 출력하는 함수이다. */
   hang ();
  }
 }

 

 /* configure available FLASH banks */
 size = flash_init ();   /* flash를 초기화 하고 size를 얻는다. */
 display_flash_config (size); /* flash의 size를 console에 출력한다. */

#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 */

 

 /* armboot_start is defined in the board-specific linker script */
 mem_malloc_init (_armboot_start - CFG_MALLOC_LEN);

 

#if (CONFIG_COMMANDS & CFG_CMD_NAND)
 puts ("NAND:");
 nand_init();  /* go init the NAND */
#endif

#ifdef CONFIG_HAS_DATAFLASH
 AT91F_DataflashInit();
 dataflash_print_info();
#endif

 

 /* initialize environment */
 env_relocate ();  /* flash에서 SDRAM으로 COPY한다. */

#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");

 /* 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;
  }
 }
 /* 설정되어 잇는 device가 있으면 초기화 한다.(i2c, LCD, keyboard) */
 devices_init (); /* get the devices list going. */

 jumptable_init ();

 console_init_r (); /* fully init console as a device */

 

#if defined(CONFIG_MISC_INIT_R)
 /* miscellaneous platform dependent initialisations */
 misc_init_r ();
#endif

 

 /* enable exceptions */
 /* interrupt를 enable한다. */
 enable_interrupts ();

 

 /* Perform network card initialisation if necessary */
#ifdef CONFIG_DRIVER_CS8900
 cs8900_get_enetaddr (gd->bd->bi_enetaddr);
#endif

#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

 

 /* main_loop() can return to retry autoboot, if so just run it again. */
 for (;;) {
  main_loop (); /* (TOPDIR)/common/main.c   여기서 main()함수로 제어가 넘어가게된다.  */
 }

 /* NOTREACHED - no way out of command loop except booting */
}

 

 

void hang (void)
{
 puts ("### ERROR ### Please RESET the board ###\n");
 for (;;);
}

#ifdef CONFIG_MODEM_SUPPORT
/* called from main loop (common/main.c) */
extern void  dbg(const char *fmt, ...);
int mdm_init (void)
{
 char env_str[16];
 char *init_str;
 int i;
 extern char console_buffer[];
 static inline void mdm_readline(char *buf, int bufsiz);
 extern void enable_putc(void);
 extern int hwflow_onoff(int);

 enable_putc(); /* enable serial_putc() */

#ifdef CONFIG_HWFLOW
 init_str = getenv("mdm_flow_control");
 if (init_str && (strcmp(init_str, "rts/cts") == 0))
  hwflow_onoff (1);
 else
  hwflow_onoff(-1);
#endif

 for (i = 1;;i++) {
  sprintf(env_str, "mdm_init%d", i);
  if ((init_str = getenv(env_str)) != NULL) {
   serial_puts(init_str);
   serial_puts("\n");
   for(;;) {
    mdm_readline(console_buffer, CFG_CBSIZE);
    dbg("ini%d: [%s]", i, console_buffer);

    if ((strcmp(console_buffer, "OK") == 0) ||
     (strcmp(console_buffer, "ERROR") == 0)) {
     dbg("ini%d: cmd done", i);
     break;
    } else /* in case we are originating call ... */
     if (strncmp(console_buffer, "CONNECT", 7) == 0) {
      dbg("ini%d: connect", i);
      return 0;
     }
   }
  } else
   break; /* no init string - stop modem init */

  udelay(100000);
 }

 udelay(100000);

 /* final stage - wait for connect */
 for(;i > 1;) { /* if 'i' > 1 - wait for connection
      message from modem */
  mdm_readline(console_buffer, CFG_CBSIZE);
  dbg("ini_f: [%s]", console_buffer);
  if (strncmp(console_buffer, "CONNECT", 7) == 0) {
   dbg("ini_f: connected");
   return 0;
  }
 }

 return 0;
}

/* 'inline' - We have to do it fast */
static inline void mdm_readline(char *buf, int bufsiz)
{
 char c;
 char *p;
 int n;

 n = 0;
 p = buf;
 for(;;) {
  c = serial_getc();

  /*  dbg("(%c)", c); */

  switch(c) {
  case '\r':
   break;
  case '\n':
   *p = '\0';
   return;

  default:
   if(n++ > bufsiz) {
    *p = '\0';
    return; /* sanity check */
   }
   *p = c;
   p++;
   break;
  }
 }
}
#endif /* CONFIG_MODEM_SUPPORT */

이로써 U-Boot분석에 필요한 파일들을 살펴보았다.  이후 각자가 사용하게 될 보드에 맞게 포팅을 할때 지금 까지 봐왔던 큰 흐름을 기억하고 그에 따르는 줄기들을 잘 분석했다면 어떤 파일들을 수정해야 하는지 감이 올 것이다.  아울러 데이터시트를 참조하는것은 기본이라는 걸 기억하면서 u-boot에 대한 공부는 마무리하도록 하겠다.(머지않아 다시 골머리를 썩겠지만 ㅋ) 

 

6주 속성으로 배우기 무지 힘들다ㅠ.ㅠㅋ  시간 날때마다 추가적으로 분석하고 주석을 달아봐야겠다.

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출처 : http://blog.naver.com/idrukawa/100054114578