jz2440 v3上面用的nandflash是 K9F2G08U0C, 大小为256MB. 一个页的大小为(2k+64)byte,一个块的大小为(128k+4k)byte,原理图如下:
nand的命令集:
那应该如何访问nand里面的数据呢?只要读写s32440的相关寄存器,就可以驱动nand的一些引脚.
Makefile
objs := head.o init.o nand.o main.o #依赖于这些文件 nand.bin : $(objs) arm-linux-ld -Tnand.lds -o nand_elf $^ #链接nand.lds $^表示所有依赖目标的集合 arm-linux-objcopy -O binary -S nand_elf $@ #规则中的目标文件集 arm-linux-objdump -D -m arm nand_elf > nand.dis %.o:%.c arm-linux-gcc -Wall -c -O2 -o $@ $< %.o:%.S arm-linux-gcc -Wall -c -O2 -o $@ $< clean: rm -f nand.dis nand.bin nand_elf *.o
nand.lds
SECTIONS { firtst 0x00000000 : { head.o init.o nand.o} //第一段的链接地址0x00000000 second 0x30000000 : AT(4096) { main.o } //main放在nand.bin的4096偏移处, 链接地址是0x30000000 }
head.S
.text .global _start @start标号作为系统启动最开始执行的地方 _start: @ ldr sp, =4096 @调用c函数之前要先设置好栈的位置,因为内部RAM大小为4k,设置在最末端 bl disable_watch_dog @调用c函数,关看门狗 bl memsetup @设置DDR,这样才能去调用它 bl nand_init @同样,也需要初始化nand @ @ ldr r0, =0x30000000 @作为nand函数的第一个参数 mov r1, #4096 @作为nand函数的第二个参数 mov r2, #2048 @作为nand函数的第三个参数 bl nand_read @ ldr sp, =0x34000000 @ ldr lr, =halt_loop @ ldr pc, =main @ת halt_loop: b halt_loop
我们先看下nand_init函数
void nand_init(void) { #define TACLS 0 #define TWRPH0 3 #define TWRPH1 0 if ((GSTATUS1 == 0x32410000) || (GSTATUS1 == 0x32410002)) { nand_chip.nand_reset = s3c2410_nand_reset; nand_chip.wait_idle = s3c2410_wait_idle; nand_chip.nand_select_chip = s3c2410_nand_select_chip; nand_chip.nand_deselect_chip = s3c2410_nand_deselect_chip; nand_chip.write_cmd = s3c2410_write_cmd; nand_chip.write_addr = s3c2410_write_addr; nand_chip.read_data = s3c2410_read_data; s3c2410nand->NFCONF = (1<<15)|(1<<12)|(1<<11)|(TACLS<<8)|(TWRPH0<<4)|(TWRPH1<<0); } else { nand_chip.nand_reset = s3c2440_nand_reset; // nand_chip.wait_idle = s3c2440_wait_idle; // nand_chip.nand_select_chip = s3c2440_nand_select_chip; // nand_chip.nand_deselect_chip = s3c2440_nand_deselect_chip; // nand_chip.write_cmd = s3c2440_write_cmd;// #ifdef LARGER_NAND_PAGE nand_chip.write_addr = s3c2440_write_addr_lp;// #else nand_chip.write_addr = s3c2440_write_addr;// #endif nand_chip.read_data = s3c2440_read_data;// s3c2440nand->NFCONF = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4); s3c2440nand->NFCONT = (1<<4)|(1<<1)|(1<<0); } nand_reset();// }
nand_reset函数
static void s3c2440_nand_reset(void) { s3c2440_nand_select_chip(); s3c2440_write_cmd(0xff); //写0xff命令代表复位 s3c2440_wait_idle(); s3c2440_nand_deselect_chip(); }/////////////////////////////////////static void s3c2440_nand_select_chip(void){ int i; s3c2440nand->NFCONT &= ~(1<<1); //改位配置成低就选中了芯片 for(i=0; i<10; i++); } static void s3c2440_write_cmd(int cmd)//这里的写命令函数其实就是往寄存器NFCMD里面写值{ volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFCMD; *p = cmd;}static void s3c2410_wait_idle(void){ int i; volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFSTAT; while(!(*p & BUSY)) //当这个寄存器的最低位为0时,表示NANDFLASH存在忙状态 for(i=0; i<10; i++);}static void s3c2410_nand_deselect_chip(void)//取消选中与选中时一种相反的操作.{ s3c2410nand->NFCONF |= (1<<11);}
void nand_read(unsigned char *buf, unsigned long start_addr, int size) { int i, j; #ifdef LARGER_NAND_PAGE if ((start_addr & NAND_BLOCK_MASK_LP) || (size & NAND_BLOCK_MASK_LP)) { return ; } #else if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK)) { return ; } #endif nand_select_chip();//选中芯片 for(i=start_addr; i < (start_addr + size);) { write_cmd(0);//先发命令0x00 /* Write Address */ write_addr(i);//再发想读的地址 #ifdef LARGER_NAND_PAGE write_cmd(0x30); //再发0x30 #endif wait_idle();//等待空闲 #ifdef LARGER_NAND_PAGE for(j=0; j < NAND_SECTOR_SIZE_LP; j++, i++) { #else for(j=0; j < NAND_SECTOR_SIZE; j++, i++) { #endif *buf = read_data(); buf++; } } nand_deselect_chip(); return ; }static unsigned char s3c2410_read_data(void){ volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFDATA; return *p;}static void s3c2410_write_addr(unsigned int addr) //因为NAND的大小为256MB,用地址来表示需要28位,地址也需要分5次写进去{ int i; volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFADDR; *p = addr & 0xff; for(i=0; i<10; i++); *p = (addr >> 9) & 0xff; for(i=0; i<10; i++); *p = (addr >> 17) & 0xff; for(i=0; i<10; i++); *p = (addr >> 25) & 0xff; for(i=0; i<10; i++);}
通过将读出来的地址写道地址偏移为0x30000000之后的内存处.
最后跳到main函数执行,查看效果可知是否拷贝成功.
来源:https://www.cnblogs.com/cheyihaosky/p/11932214.html