一个简单的bootloader程序

#define NFCONF (*(volatile unsigned long*)0x4E000000) #define NFCONT (*(volatile unsigned long*)0x4E000004) #define NFCMD (*(volatile unsigned char*)0x4E000008) #define NFADDR (*(volatile unsigned char*)0x4E00000C) #define NFDATA (*(volatile unsigned char*)0x4E000010) #define NFSTAT (*(volatile unsigned char*)0x4E000020) #define TACLS 0 #define TWRPH0 1 #define TWRPH1 0 void wait(volatile int i) { volatile int j=i; for(j=0;j<10;j++); } void select_chip() { NFCONT &= ~(1<<1); } void deselect_chip() { NFCONT |= (1<<1); } void clear_RnB() { NFSTAT |= (1<<2); } void send_cmd(unsigned cmd) { NFCMD = cmd; } void send_addr(unsigned addr) { NFADDR = addr; wait(10); } void wait_RnB() { while (!(NFSTAT&(1<<2))); } void nand_reset() { //选中flash select_chip(); //清除RnB clear_RnB(); //发送0xff命令 send_cmd(0xff); //等待RnB wait_RnB(); //取消选中flash deselect_chip(); } void nandflash_init() { //初始化NFCONF NFCONF = (TACLS<<12) | (TWRPH0<<8) | (TWRPH1<<4); //初始化NFCONT NFCONT = (1<<0) | (1<<1)|(1<<4); //复位 nand_reset(); } void NF_PageRead(unsigned long addr,unsigned char* buff) { int i; //选中nandflash芯片 select_chip(); //清除RnB clear_RnB(); //发送命令0x00 send_cmd(0x00); //发送列地址 send_addr(0x00); send_addr(0x00); //发送行地址 send_addr(addr&0xff); send_addr((addr>>8)&0xff); send_addr((addr>>16)&0xff); //发送命令0x30 send_cmd(0x30); //等待RnB wait_RnB(); //读取数据 for(i=0;i<2048;i++) { buff[i] = NFDATA; } //取消选中nandflash芯片 deselect_chip(); } void nand_to_ram(unsigned long start_addr, unsigned char* sdram_addr, int size) { int i; for( i=(start_addr >>11); size>0;) { NF_PageRead(i,sdram_addr); size -= 2048; sdram_addr += 2048; i++; } } int NF_Erase(unsigned long addr) { int ret; //选中flash芯片 select_chip(); //清除RnB clear_RnB(); //发送命令0x60 send_cmd(0x60); //发送行地址 send_addr(addr&0xff); send_addr((addr>>8)&0xff); send_addr((addr>>16)&0xff); //发送命令D0 send_cmd(0xD0); //等待RnB wait_RnB(); //发送命令0x70 send_cmd(0x70); //读取擦除结果 ret = NFDATA; //取消选中flash芯片 deselect_chip(); return ret; } int NF_WritePage(unsigned long addr,unsigned char *buff) { unsigned int i,ret = 0; //选中nandflash select_chip(); //清除RnB clear_RnB(); //发送0x80命令 send_cmd(0x80); //发送2个列地址 send_addr(0x00); send_addr(0x00); //发送3个行地址 send_addr(addr&0xff); send_addr((addr>>8)&0xff); send_addr((addr>>16)&0xff); //发送数据 for(i=0;i<2048;i++) { NFDATA = buff[i]; } //发送0x10命令 send_cmd(0x10); //等待RnB wait_RnB(); //发送0x70命令 send_cmd(0x70); //读取写入结果 ret = NFDATA; //关闭nandflash deselect_chip(); return ret; }