自己寫(xiě)bootloader

// NAND FLASH控制器 //

#define NFCONF (*((volatile unsigned long *)0x4E000000))

#define NFCONT (*((volatile unsigned long *)0x4E000004))

#define NFCMMD (*((volatile unsigned char *)0x4E000008))

#define NFADDR (*((volatile unsigned char *)0x4E00000C))

#define NFDATA (*((volatile unsigned char *)0x4E000010))

#define NFSTAT (*((volatile unsigned char *)0x4E000020))

void nand_init(void)

{

#define TACLS 0

#define TWRPH0 3

#define TWRPH1 0

// 設(shè)置時(shí)序 //

NFCONF = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4);

// 使能NAND Flash控制器, 初始化ECC, 禁止片選 //

NFCONT = (1<<4)|(1<<1)|(1<<0);

}

void nand_select(void)

{

NFCONT &= ~(1<<1);

}

void del_select(void)

{

NFCONT |= (1<<1);

}

void nand_cmd(unsigned char cmd)

{

volatile int i=0;

NFCMMD = cmd;

for(i=0; i<10; i++);

}

void nand_wait_ready(void)

{

while (!(NFSTAT & 1));

}

unsigned char nand_data(void)

{

return NFDATA;

}

void nand_addr(unsigned int addr)

{

unsigned int col = addr % 2048;

unsigned int page = addr / 2048;

unsigned int i=0;

NFADDR = col & 0xff;

for(i=0; i<10; i++);

NFADDR = (col>>8) & 0xff;

for(i=0; i<10; i++);

NFADDR = page & 0xff;

for(i=0; i<10; i++);

NFADDR = (page>>8) & 0xff;

for(i=0; i<10; i++);

NFADDR = (page>>16) & 0xff;

for(i=0; i<10; i++);

}

//addr--->0,下面的nand_read函數(shù)從nand flash的0地址讀數(shù)據(jù)放在buf地方

//buf---->_start 即鏈接地址在鏈接腳本中注明,程序運(yùn)行時(shí)應(yīng)該在的地方，0x33f80000，把程序拷貝過(guò)去

//len----->__bss_start-_start

void nand_read(unsigned int addr, unsigned char *buf, unsigned int len)

{

int col = addr 48;

int i = 0;

// 選中片選 //

nand_select();

while(i

{

// 發(fā)讀命令 //

nand_cmd(0x00);

// 發(fā)地址 //

nand_addr(addr);

// 發(fā)讀命令 //

nand_cmd(0x30);

// 判斷狀態(tài) //

nand_wait_ready();

// 讀數(shù)據(jù) //

for(; (col<2048) && (i

{

buf[i] = nand_data();

i++;

addr++;

}

col = 0;

}

// 取消片選 //

del_select();

}

//

為什么該函數(shù)能夠判斷成功，因?yàn)槌绦蜻\(yùn)行到此時(shí)如果是nand啟動(dòng)，則上電后nand flash的前4K會(huì)被復(fù)制到片內(nèi)SARM中運(yùn)行，往地址0寫(xiě)入數(shù)據(jù)相當(dāng)于往片內(nèi)內(nèi)存0地址寫(xiě)數(shù)據(jù)可以成功；但是如果是nor啟動(dòng)，上電后直接在nor的0地址運(yùn)行，程序依然在nor flash中，nor flash可以像內(nèi)存一樣讀，但是無(wú)法像內(nèi)存一樣寫(xiě)，故直接向0地址賦值會(huì)失敗。

//

int isBootFromNorFlash(void)

{

volatile int *p =(volatile int *)0;

int val=0;

val = *p;

*p = 0x1234ab;

if(*p == 0x1234ab)

{

//寫(xiě)成功，表示是nand flash啟動(dòng)

*p=val;

return 0;

}

else

{

//寫(xiě)失敗，說(shuō)明是nor flash啟動(dòng)

return 1;

}

}

void copy_code_to_sdram(unsigned char *src, unsigned char *dest, unsigned int len)

{

unsigned int i=0;

if(isBootFromNorFlash())//nor啟動(dòng)

{

while(i

{

dest[i] = src[i];

i++;

}

}

else //nand啟動(dòng)

{

nand_read(src,dest,len);

}

}

void clear_bss(void)

{

extern int __bss_start, __bss_end;

int *p = &__bss_start;

for(; p < &__bss_end; p++)

*p = 0;

}

#define PCLK 50000000 // init.c中的clock_init函數(shù)設(shè)置PCLK為50MHz

#define UART_CLK PCLK // UART0的時(shí)鐘源設(shè)為PCLK

#define UART_BAUD_RATE 115200 // 波特率

#define UART_BRD ((UART_CLK / (UART_BAUD_RATE * 16)) - 1)

//

* 初始化UART0

* 115200,8N1,無(wú)流控

//

void uart0_init(void)

{

GPHCON |= 0xa0; // GPH2,GPH3用作TXD0,RXD0

GPHUP = 0x0c; // GPH2,GPH3內(nèi)部上拉

ULCON0 = 0x03; // 8N1(8個(gè)數(shù)據(jù)位，無(wú)較驗(yàn)，1個(gè)停止位)

UCON0 = 0x05; // 查詢(xún)方式，UART時(shí)鐘源為PCLK

UFCON0 = 0x00; // 不使用FIFO

UMCON0 = 0x00; // 不使用流控

UBRDIV0 = UART_BRD; // 波特率為115200

}

//

* 發(fā)送一個(gè)字符

//

void putc(unsigned char c)

{

// 等待，直到發(fā)送緩沖區(qū)中的數(shù)據(jù)已經(jīng)全部發(fā)送出去 //

while (!(UTRSTAT0 & TXD0READY));

// 向UTXH0寄存器中寫(xiě)入數(shù)據(jù)，UART即自動(dòng)將它發(fā)送出去 //

UTXH0 = c;

}

void puts(char *str)

{

int i = 0;

while (str[i])

{

putc(str[i]);

i++;

}

}

void puthex(unsigned int val)

{

// 0x1234abcd //

int i;

int j;

puts("0x");

for (i = 0; i < 8; i++)

{

j = (val >> ((7-i)*4)) & 0xf;

if ((j >= 0) && (j <= 9))

putc(0 + j);

else

putc(A + j - 0xa);

}

}

=================================================================

#include "setup.h"

extern void uart0_init(void);

extern void nand_read(unsigned int addr, unsigned char *buf, unsigned int len);

extern void puts(char *str);

extern void puthex(unsigned int val);

static struct tag *params;

void setup_start_tag(void)

{

params = (struct tag *)0x30000100;

params->hdr.tag = ATAG_CORE;

params->hdr.size = tag_size (tag_core);

params->u.core.flags = 0;

params->u.core.pagesize = 0;

params->u.core.rootdev = 0;

params = tag_next (params);

}

void setup_memory_tags(void)

{

params->hdr.tag = ATAG_MEM;

params->hdr.size = tag_size (tag_mem32);

params->u.mem.start = 0x30000000;

params->u.mem.size = 64*1024*1024;

params = tag_next (params);

}

int strlen(char *str)

{

int i = 0;

while (str[i])

{

i++;

}

return i;

}

void strcpy(char *dest, char *src)

{

while ((*dest++ = *src++) !=