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这是一个NAND访问的实验。小弟有一些问题请教给位，希望大家赐教一下。具体问题已经代码相应的位置标出。谢谢<br /><br />@******************************************************************************<br />@ File：head.s<br />@ 功能：设置SDRAM，将程序复制到SDRAM，然后跳到SDRAM继续执行<br />@****************************************************************************** <br /> <br />.text<br />.global _start<br />_start:<br /> @函数disable_watch_dog, memsetup, init_nand, nand_read_ll在init.c中定义<br /> ldr sp, =4096 @设置堆栈 。设置在这里那里有空间呢?<br /> bl disable_watch_dog @关WATCH DOG<br /> bl memsetup @初始化SDRAM<br /> bl nand_init @初始化NAND Flash<br /><br /> @将NAND Flash中地址4096开始的1024字节代码(main.c编译得到)复制到SDRAM中<br /> @nand_read函数需要3个参叔(这3个参数是怎样和nand_read函数联系在一起?可以怎样传递参数？)：<br /> ldr r0, =0x30000000 @1. 目标地址=0x30000000，这是SDRAM的起始地址<br /> mov r1, #4096 @2. 源地址 = 4096，连接的时候，main.c中的代码都存在NAND Flash地址4096开始处<br /> mov r2, #1024 @3. 复制长度= 1024(bytes)，对于本实验的main.c，这是足够了<br /> bl nand_read @调用C函数nand_read，<br /> <br /> ldr sp, =0x34000000 @设置栈<br /> ldr lr, =halt_loop @设置返回地址<br /> ldr pc, =main @在b指令和bl指令只能前后跳转32M的范围，所以这里使用向pc赋值的方法进行跳转<br />halt_loop:<br /> b halt_loop @ 它的作用应该和while(1)一样，它是怎么一个工作方式。死循环?那程序不是卡在这里? <br /><br /><br />nand.c<br /><br />#define GSTATUS1 (*(volatile unsigned int *)0x560000b0)<br />#define BUSY 1<br /><br />typedef unsigned int S3C24X0_REG32; //typedef并不创建新的类型,它仅仅为现有类型添加一个别名。此处为unsigned int新建一个叫做S3C24X0_REG32的别名。<br /><br /><br />/* NAND FLASH (see S3C2410 manual chapter 6) */<br />typedef struct { //定义一个结构体，没有命名<br /> S3C24X0_REG32 NFCONF; <br /> S3C24X0_REG32 NFCMD;<br /> S3C24X0_REG32 NFADDR;<br /> S3C24X0_REG32 NFDATA;<br /> S3C24X0_REG32 NFSTAT;<br /> S3C24X0_REG32 NFECC;<br />} S3C2410_NAND; //S3C2410_NAND为之前定义的结构体的一个别名<br /><br />/* NAND FLASH (see S3C2440 manual chapter 6, www.100ask.net) */<br />typedef struct {<br /> S3C24X0_REG32 NFCONF;<br /> S3C24X0_REG32 NFCONT;<br /> S3C24X0_REG32 NFCMD;<br /> S3C24X0_REG32 NFADDR;<br /> S3C24X0_REG32 NFDATA;<br /> S3C24X0_REG32 NFMECCD0;<br /> S3C24X0_REG32 NFMECCD1;<br /> S3C24X0_REG32 NFSECCD;<br /> S3C24X0_REG32 NFSTAT;<br /> S3C24X0_REG32 NFESTAT0;<br /> S3C24X0_REG32 NFESTAT1;<br /> S3C24X0_REG32 NFMECC0;<br /> S3C24X0_REG32 NFMECC1;<br /> S3C24X0_REG32 NFSECC;<br /> S3C24X0_REG32 NFSBLK;<br /> S3C24X0_REG32 NFEBLK;<br />} S3C2440_NAND;<br /><br /><br />typedef struct { <br /> void (*nand_reset)(void); //nand_reset前面的＊表示nand_reset是一个指针变量，而nand_reset是一个函数，函数名代表该函数的入口地址。<br /> void (*wait_idle)(void); //因此，nand_reset是一个函数指针。一个函数在编译的时候会被分配一个入口地址，这个入口地址就是称为函数的指针，<br /> void (*nand_select_chip)(void);//可以用一个指针变量指向函数，然后通过该指针变量调用此函数。<br /> void (*nand_deselect_chip)(void);<br /> void (*write_cmd)(int cmd);<br /> void (*write_addr)(unsigned int addr);<br /> unsigned char (*read_data)(void);<br />}t_nand_chip;<br /> //一个结构体变量的指针就是该变量所占据的内存段的起始地址。可以设置一个指针变量，用来<br /> //指向一个结构体变量，此时该指针变量的值就是该结构体变量的起始地址。<br /> //s3c2410nand是指向一个S3C2410_NAND类型的指针变量。<br />static S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000; //0x4e000000为某一个S3C2410_NAND类型变量的起始地址。<br />static S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000; //该语句表示设置指针变量s3c2410nand所占据的内存起始地址为0x4e000000<br /> //s3c2410nand是一个静态外部变量。只限于该文件内（nand.c）的函数调用。其他文件不能<br /> //调用。<br />static t_nand_chip nand_chip;//nand_chip,静态全局变量，变量类型为t_nand_chip（结构体），只局限于本文件有效。<br /><br />/* 供外部调用的函数 */<br />void nand_init(void);<br />void nand_read(unsigned char *buf, unsigned long start_addr, int size);<br /><br />/* NAND Flash操作的总入口, 它们将调用S3C2410或S3C2440的相应函数 */<br />static void nand_reset(void); //静态函数，又称内部函数，该类型函数只局限于所在文件，若其他文件中有同名的内部函数，互不干扰。复位<br />static void wait_idle(void); //idle空闲。等待就绪<br />static void nand_select_chip(void);//片选<br />static void nand_deselect_chip(void);//取消片选<br />static void write_cmd(int cmd);//写命令<br />static void write_addr(unsigned int addr);//写地址<br />static unsigned char read_data(void);//读数据<br /><br />/* S3C2410的NAND Flash处理函数 */<br />static void s3c2410_nand_reset(void);<br />static void s3c2410_wait_idle(void);<br />static void s3c2410_nand_select_chip(void);<br />static void s3c2410_nand_deselect_chip(void);<br />static void s3c2410_write_cmd(int cmd);<br />static void s3c2410_write_addr(unsigned int addr);<br />static unsigned char s3c2410_read_data();<br /><br />/* S3C2440的NAND Flash处理函数 */<br />static void s3c2440_nand_reset(void);<br />static void s3c2440_wait_idle(void);<br />static void s3c2440_nand_select_chip(void);<br />static void s3c2440_nand_deselect_chip(void);<br />static void s3c2440_write_cmd(int cmd);<br />static void s3c2440_write_addr(unsigned int addr);<br />static unsigned char s3c2440_read_data(void);<br /><br />/* S3C2410的NAND Flash操作函数 */<br /><br />/* 复位 */<br />static void s3c2410_nand_reset(void)<br />{<br /> s3c2410_nand_select_chip();<br /> s3c2410_write_cmd(0xff); // 复位命令<br /> s3c2410_wait_idle();<br /> s3c2410_nand_deselect_chip();<br />}<br /><br />/* 等待NAND Flash就绪 */<br />static void s3c2410_wait_idle(void)<br />{<br /> int i;<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFSTAT;//&s3c2410nand->NFSTAT返回NFSTAT的地址，由于<br /> //s3c2410nand的数据类型是结构体S3C2410_NAND，所以要进行<br /> //地址转换——unsigned char *<br /> while(!(*p & BUSY)) //*P返回NFSTAT的值 <br /> for(i=0; i<10; i++);<br />}<br /><br />/* 发出片选信号 */<br />static void s3c2410_nand_select_chip(void)<br />{<br /> int i;<br /> s3c2410nand->NFCONF &= ~(1<<11);<br /> for(i=0; i<10; i++); <br />}<br /><br />/* 取消片选信号 */<br />static void s3c2410_nand_deselect_chip(void)<br />{<br /> s3c2410nand->NFCONF |= (1<<11);<br />}<br /><br />/* 发出命令 */<br />static void s3c2410_write_cmd(int cmd)<br />{<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFCMD;<br /> *p = cmd;<br />}<br /><br />/* 发出地址 */<br />static void s3c2410_write_addr(unsigned int addr) //addr为地址序列<br />{<br /> int i;<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFADDR;<br /> <br /> *p = addr & 0xff;//第一个地址序列A0～A7<br /> for(i=0; i<10; i++);<br /> *p = (addr >> 9) & 0xff;//第二个地址序列A9～A16<br /> for(i=0; i<10; i++);<br /> *p = (addr >> 17) & 0xff;//第三个地址序列A17～A24<br /> for(i=0; i<10; i++);<br /> *p = (addr >> 25) & 0xff;//第四个地址序列A25<br /> for(i=0; i<10; i++);<br />}<br /><br />/* 读取数据 */<br />static unsigned char s3c2410_read_data(void)<br />{<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFDATA;<br /> return *p;<br />}<br /><br />/* S3C2440的NAND Flash操作函数 */<br /><br />/* 复位 */<br />static void s3c2440_nand_reset(void)<br />{<br /> s3c2440_nand_select_chip();<br /> s3c2440_write_cmd(0xff); // 复位命令<br /> s3c2440_wait_idle();<br /> s3c2440_nand_deselect_chip();<br />}<br /><br />/* 等待NAND Flash就绪 */<br />static void s3c2440_wait_idle(void)<br />{<br /> int i;<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFSTAT;<br /> while(!(*p & BUSY))<br /> for(i=0; i<10; i++);<br />}<br /><br />/* 发出片选信号 */<br />static void s3c2440_nand_select_chip(void)<br />{<br /> int i;<br /> s3c2440nand->NFCONT &= ~(1<<1);<br /> for(i=0; i<10; i++); <br />}<br /><br />/* 取消片选信号 */<br />static void s3c2440_nand_deselect_chip(void)<br />{<br /> s3c2440nand->NFCONT |= (1<<1);<br />}<br /><br />/* 发出命令 */<br />static void s3c2440_write_cmd(int cmd)<br />{<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFCMD;<br /> *p = cmd;<br />}<br /><br />/* 发出地址 */<br />static void s3c2440_write_addr(unsigned int addr)<br />{<br /> int i;<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFADDR;<br /> <br /> *p = addr & 0xff;<br /> for(i=0; i<10; i++);<br /> *p = (addr >> 9) & 0xff;<br /> for(i=0; i<10; i++);<br /> *p = (addr >> 17) & 0xff;<br /> for(i=0; i<10; i++);<br /> *p = (addr >> 25) & 0xff;<br /> for(i=0; i<10; i++);<br />}<br /><br />/* 读取数据 */<br />static unsigned char s3c2440_read_data(void)<br />{<br /> volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFDATA;<br /> return *p;<br />}<br /><br /><br />/* 在第一次使用NAND Flash前，复位一下NAND Flash */<br />static void nand_reset(void)<br />{<br /> nand_chip.nand_reset();<br />}<br /><br />static void wait_idle(void) <br />{<br /> nand_chip.wait_idle(); <br />}<br /><br />static void nand_select_chip(void)<br />{<br /> int i;<br /> nand_chip.nand_select_chip();<br /> for(i=0; i<10; i++);<br />}<br /><br />static void nand_deselect_chip(void)<br />{<br /> nand_chip.nand_deselect_chip();<br />}<br /><br />static void write_cmd(int cmd)<br />{<br /> nand_chip.write_cmd(cmd);<br />}<br />static void write_addr(unsigned int addr)<br />{<br /> nand_chip.write_addr(addr);<br />}<br /><br />static unsigned char read_data(void)<br />{<br /> return nand_chip.read_data();<br />}<br /><br /><br />/* 初始化NAND Flash */<br />void nand_init(void)<br />{<br />#define TACLS 0<br />#define TWRPH0 3<br />#define TWRPH1 0<br /><br /> /* 判断是S3C2410还是S3C2440 */<br /> if ((GSTATUS1 == 0x32410000) || (GSTATUS1 == 0x32410002))<br /> {<br /> nand_chip.nand_reset = s3c2410_nand_reset;<br /> nand_chip.wait_idle = s3c2410_wait_idle;<br /> nand_chip.nand_select_chip = s3c2410_nand_select_chip;<br /> nand_chip.nand_deselect_chip = s3c2410_nand_deselect_chip;<br /> nand_chip.write_cmd = s3c2410_write_cmd;<br /> nand_chip.write_addr = s3c2410_write_addr;<br /> nand_chip.read_data = s3c2410_read_data;<br /><br /> /* 使能NAND Flash控制器, 初始化ECC, 禁止片选, 设置时序 */<br /> s3c2410nand->NFCONF = (1<<15)|(1<<12)|(1<<11)|(TACLS<<8)|(TWRPH0<<4)|(TWRPH1<<0);//访问结构体里面的NFCONF成员。等价于<br /> //*s3c2410nand.NFCONF，结构体变量.NFCONF<br /><br /> }<br /> else<br /> {<br /> nand_chip.nand_reset = s3c2440_nand_reset;<br /> nand_chip.wait_idle = s3c2440_wait_idle;<br /> nand_chip.nand_select_chip = s3c2440_nand_select_chip;<br /> nand_chip.nand_deselect_chip = s3c2440_nand_deselect_chip;<br /> nand_chip.write_cmd = s3c2440_write_cmd;<br /> nand_chip.write_addr = s3c2440_write_addr;<br /> nand_chip.read_data = s3c2440_read_data;<br /><br /> /* 设置时序 */<br /> s3c2440nand->NFCONF = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4);<br /> /* 使能NAND Flash控制器, 初始化ECC, 禁止片选 */<br /> s3c2440nand->NFCONT = (1<<4)|(1<<1)|(1<<0);<br /> }<br /> <br /> /* 复位NAND Flash */<br /> nand_reset();<br />}<br /><br /><br />#define NAND_SECTOR_SIZE 512<br />#define NAND_BLOCK_MASK (NAND_SECTOR_SIZE - 1)<br /><br />/* 读函数 */<br />void nand_read(unsigned char *buf, unsigned long start_addr, int size)<br />{<br /> int i, j;<br /> <br /> if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK)) { //地址或长度不对齐。 判断依据是什么? <br /> return ; <br /> }<br /><br /> /* 选中芯片 */<br /> nand_select_chip();<br /><br /> for(i=start_addr; i < (start_addr + size);) {<br /> /* 发出READ0命令 */<br /> write_cmd(0);<br /><br /> /* Write Address */<br /> write_addr(i);<br /> wait_idle();<br /><br /> for(j=0; j < NAND_SECTOR_SIZE; j++, i++) {<br /> *buf = read_data();<br /> buf++;<br /> }<br /> }<br /><br /> /* 取消片选信号 */<br /> nand_deselect_chip();<br /> <br /> return ;<br />} |
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