main.c

ARM-LINUX,基于S3c2410处理器的开发板实验源代码

/*
 * vivi/main.c: main routine 
 *
 * Copyright (C) 2001,2002 MIZI Research, Inc.
 *
 * 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
 *
 *
 * Author: Janghoon Lyu <[e-mail]>
 * Date  : $Date: 2002/08/28 06:00:11 $
 *
 * $Revision: 1.7 $
 * $Id: main.c,v 1.7 2002/08/28 06:00:11 nandy Exp $
 *
 *
 * History
 *
 * 2001-10-xx: Janghoon Lyu <[e-mail]>
 *    - Initial code
 *
 * 2001-01-26: Janghoon Lyu <[e-mail]>
 *    - Release VIVI Bootloader
 *
 * 2002-07-02: Janghoon Lyu <[e-mail]>
 *    - bootldr狼 儡犁甫 没家窍搁辑 货酚霸 累己
 */

#include "config.h"
#include "machine.h"
#include "mmu.h"
#include "heap.h"
#include "serial.h"
#include "printk.h"
#include "command.h"
#include "priv_data.h"
#include "getcmd.h"
#include "vivi_string.h"
#include "mtd/mtd.h"
#include "processor.h"
#include <reset_handle.h>
#include <types.h>
    
extern char *vivi_banner;

void 
vivi_shell(void)
{
#ifdef CONFIG_SERIAL_TERM   /*CONFIG_SERIAL_TERM=y*/
    serial_term();  /*drivers/serial/term.c*/
#else
#error there is no terminal.
#endif
}

void run_autoboot(void)
{
/*defined at lib/boot_kernel.c
user_command_t boot_cmd = {
    "boot",
    command_boot, //defined at lib/boot_kernel.c
    NULL,
    "boot [{cmds}] \t\t\t-- Booting linux kernel"
};
*/
    while (1) {
        exec_string("boot");      /*lib/command.c*/ 
        printk("Failed 'boot' command. reentering vivi shell\n");
        /* if default boot fails, drop into the shell */
        vivi_shell();
    }
}

static void 
error(void)
{
    putstr("Sorry. We can not run vivi\n");
    for (;;) /* nothing */;     /* infinite loop */
}

#define DEFAULT_BOOT_DELAY  0x30000000
void boot_or_vivi(void)
{
    char c;
    int ret;
    ulong boot_delay;

/*在include/priv_data.h中定义
typedef struct parameter {
    char name[MAX_PARAM_NAME];
    param_value_t value;
    void (*update_func)(param_value_t value);
} vivi_parameter_t; 
*/
/*在arch/s3c2410/smdk.c中定义
vivi_parameter_t default_vivi_parameters[] = {
    { "mach_type",          MACH_TYPE,  NULL },
    { "media_type",         MT_S3C2410, NULL },
    { "boot_mem_base",      0x30000000, NULL },
    { "baudrate",           UART_BAUD_RATE, NULL },
    { "xmodem_one_nak",     0,      NULL },
    { "xmodem_initial_timeout", 300000,     NULL },
    { "xmodem_timeout",     1000000,    NULL },
    { "ymodem_initial_timeout", 1500000,    NULL },
    { "boot_delay",         0x1000,     NULL }
};
*/
    boot_delay = get_param_value("boot_delay", &ret);   /*lib/priv_data/param.c*/
    if (ret) boot_delay = DEFAULT_BOOT_DELAY;
    /* If a value of boot_delay is zero, 
     * unconditionally call vivi shell */
    if (boot_delay == 0) vivi_shell();


    /*
     * wait for a keystroke (or a button press if you want.)
     */
    printk("Press Return to start the LINUX now, any other key for vivi\n");
    c = awaitkey(boot_delay, NULL); /*drivers/serial/serial_core.c*/
    if (((c != '\r') && (c != '\n') && (c != '\0'))) {
        printk("type \"help\" for help.\n");
        vivi_shell();
    }
    run_autoboot();

    return;
}


/**************************************************************************************************
*what main do(this is the stage2 of bootloader):
*
*
*
*
**************************************************************************************************/
int main(int argc, char *argv[])
{
    int ret;

    /* NB: 酒流鳖瘤绰 MMU啊 波廉 乐澜. */
    /*
     * Step 1:
     *  老窜 埃窜茄 硅呈窍唱 谎府绊..
     */
    putstr("\r\n");
    putstr(vivi_banner);

    reset_handler();    /*lib/reset_handle.c    */
            /*it calls function clear_mem((unsigned long)USER_RAM_BASE, (unsigned long)USER_RAM_SIZE) in lib/memory.c*/
            /*I can't find where USER_RAM_BASE and USER_RAM_SIZE were defined. */

    /*
     * Step 2:
     *   Board甫 檬扁拳 钦聪促.
     */
    ret = board_init(); /*arch/s3c2410/smdk.c*/
            /*it calls init_time(at arch/s3c2410/proc.c) and set_gpios(in arch/s3c2410/smdk.c)*/
            /*init_time: TCFG0 = 0 | 0xf00 | 0 */
            
    if (ret) {
        putstr("Failed a board_init() procedure\r\n");
        error();
    }

    /*
     * Step 3:
     *   4G甫 府聪绢(linear)窍霸 概俏窍绊, 敲贰浆 皋葛府甫
     *   盔窍绰 措肺 概俏窍绊,
     *   MMU甫 难技夸.
     */
    mem_map_init(); /*arch/s3c2410/mmu.c line194*/
            /*1. call mem_map_nand_boot in arch/s3c2410/mmu.c
                this function call mem_mapping_linear immediately
                    mem_mapping_linear(arch/s3c2410/mmu.c):
                          initialize the mmu translation table, Make DRAM section cacheable 
              2. call cache_clean_invalidate in arch/s3c2410/mmu.c:  clean and invalidate all cache lines
              3. call tlb_invalidate in arch/s3c2410/mmu.c: invalidate I & D TLBs
            */

    mmu_init(); /*arch/s3c2410/mmu.c line120*/
            /*call arm920_setup in arch/s3c2410/mmu.c:
                1. invalidate I,D caches
                2. drain write buffer