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U-boot学习笔记(二)

发布时间：2020-12-15 06:32:15 所属栏目：百科 来源：网络整理
导读：让U-boot支持NAND Flash启动 修改cpu/arm920t/start.S修改代码搬移程序 #if 1bl CopyCode2Ram/* r0: source,r1: dest,r2: size */#elseaddr2,r0,r2/* r2 - source end address */copy_loop:ldmiar0!,{r3-r10}/* copy from source address [r0] */stmiar1!,{r

让U-boot支持NAND Flash启动

  • 修改cpu/arm920t/start.S修改代码搬移程序

#if 1
	bl  CopyCode2Ram	/* r0: source,r1: dest,r2: size */
#else
	add	r2,r0,r2		/* r2 <- source end address         */

copy_loop:
	ldmia	r0!,{r3-r10}		/* copy from source address [r0]    */
	stmia	r1!,{r3-r10}		/* copy to   target address [r1]    */
	cmp	r0,r2			/* until source end addreee [r2]    */
	ble	copy_loop
#endif

  • 增加CopyCode2Ram函数以及子函数,修改board目录下目标板的boot_init.c。

#include <common.h>
#include <s3c2410.h>

#define BUSY            1

#define NAND_SECTOR_SIZE    512
#define NAND_BLOCK_MASK     (NAND_SECTOR_SIZE - 1)

#define NAND_SECTOR_SIZE_LP    2048
#define NAND_BLOCK_MASK_LP     (NAND_SECTOR_SIZE_LP - 1)

/* 供外部调用的函数 */
void nand_init_ll(void);
void nand_read_ll(unsigned char *buf,unsigned long start_addr,int size);

/* NAND Flash操作的总入口,它们将调用S3C2410或S3C2440的相应函数 */
static void nand_reset(void);
static void wait_idle(void);
static void nand_select_chip(void);
static void nand_deselect_chip(void);
static void write_cmd(int cmd);
static void write_addr(unsigned int addr);
static unsigned char read_data(void);

/* S3C2410的NAND Flash处理函数 */
static void s3c2410_nand_reset(void);
static void s3c2410_wait_idle(void);
static void s3c2410_nand_select_chip(void);
static void s3c2410_nand_deselect_chip(void);
static void s3c2410_write_cmd(int cmd);
static void s3c2410_write_addr(unsigned int addr);
static unsigned char s3c2410_read_data(void);

/* S3C2440的NAND Flash处理函数 */
static void s3c2440_nand_reset(void);
static void s3c2440_wait_idle(void);
static void s3c2440_nand_select_chip(void);
static void s3c2440_nand_deselect_chip(void);
static void s3c2440_write_cmd(int cmd);
static void s3c2440_write_addr(unsigned int addr);
static unsigned char s3c2440_read_data(void);

/* S3C2410的NAND Flash操作函数 */

/* 复位 */
static void s3c2410_nand_reset(void)
{
    s3c2410_nand_select_chip();
    s3c2410_write_cmd(0xff);  // 复位命令
    s3c2410_wait_idle();
    s3c2410_nand_deselect_chip();
}

/* 等待NAND Flash就绪 */
static void s3c2410_wait_idle(void)
{
    int i;
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;
	
    volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFSTAT;
    while(!(*p & BUSY))
        for(i=0; i<10; i++);
}

/* 发出片选信号 */
static void s3c2410_nand_select_chip(void)
{
    int i;
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;

    s3c2410nand->NFCONF &= ~(1<<11);
    for(i=0; i<10; i++);    
}

/* 取消片选信号 */
static void s3c2410_nand_deselect_chip(void)
{
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;

    s3c2410nand->NFCONF |= (1<<11);
}

/* 发出命令 */
static void s3c2410_write_cmd(int cmd)
{
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;

    volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFCMD;
    *p = cmd;
}

/* 发出地址 */
static void s3c2410_write_addr(unsigned int addr)
{
    int i;
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;
    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++);
}

/* 读取数据 */
static unsigned char s3c2410_read_data(void)
{
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;

    volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFDATA;
    return *p;
}

/* S3C2440的NAND Flash操作函数 */

/* 复位 */
static void s3c2440_nand_reset(void)
{
    s3c2440_nand_select_chip();
    s3c2440_write_cmd(0xff);  // 复位命令
    s3c2440_wait_idle();
    s3c2440_nand_deselect_chip();
}

/* 等待NAND Flash就绪 */
static void s3c2440_wait_idle(void)
{
    int i;
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;
    volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFSTAT;

    while(!(*p & BUSY))
        for(i=0; i<10; i++);
}

/* 发出片选信号 */
static void s3c2440_nand_select_chip(void)
{
    int i;
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;

    s3c2440nand->NFCONT &= ~(1<<1);
    for(i=0; i<10; i++);    
}

/* 取消片选信号 */
static void s3c2440_nand_deselect_chip(void)
{
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;

    s3c2440nand->NFCONT |= (1<<1);
}

/* 发出命令 */
static void s3c2440_write_cmd(int cmd)
{
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;

    volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFCMD;
    *p = cmd;
}

/* 发出地址 */
static void s3c2440_write_addr(unsigned int addr)
{
    int i;
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;
    volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->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++);
}


/* 发出地址 */
static void s3c2440_write_addr_lp(unsigned int addr)
{
    int i;
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;
    volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFADDR;
	int col,page;

	col = addr & NAND_BLOCK_MASK_LP;
	page = addr / NAND_SECTOR_SIZE_LP;
	
    *p = col & 0xff;			/* Column Address A0~A7 */
    for(i=0; i<10; i++);		
    *p = (col >> 8) & 0x0f;		/* Column Address A8~A11 */
    for(i=0; i<10; i++);
    *p = page & 0xff;			/* Row Address A12~A19 */
    for(i=0; i<10; i++);
    *p = (page >> 8) & 0xff;	/* Row Address A20~A27 */
    for(i=0; i<10; i++);
    *p = (page >> 16) & 0x03;	/* Row Address A28~A29 */
    for(i=0; i<10; i++);
}

/* 读取数据 */
static unsigned char s3c2440_read_data(void)
{
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;
    volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFDATA;
    return *p;
}


/* 在第一次使用NAND Flash前，复位一下NAND Flash */
static void nand_reset(void)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_nand_reset();
	}
	else
	{
	    s3c2440_nand_reset();
	}
}

static void wait_idle(void)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_wait_idle();
	}
	else
	{
	    s3c2440_wait_idle();
	}
}

static void nand_select_chip(void)
{
    int i;
	
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_nand_select_chip();
	}
	else
	{
	    s3c2440_nand_select_chip();
	}
	
    for(i=0; i<10; i++);
}

static void nand_deselect_chip(void)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_nand_deselect_chip();
	}
	else
	{
	    s3c2440_nand_deselect_chip();
	}	
}

static void write_cmd(int cmd)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_write_cmd(cmd);
	}
	else
	{
	    s3c2440_write_cmd(cmd);
	}	
}
static void write_addr(unsigned int addr)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_write_addr(addr);
	}
	else
	{
	    s3c2440_write_addr(addr);
	}	
}

static void write_addr_lp(unsigned int addr)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    s3c2410_write_addr(addr);
	}
	else
	{
	    s3c2440_write_addr_lp(addr);
	}	
}

static unsigned char read_data(void)
{
    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
	{
	    return s3c2410_read_data();
	}
	else
	{
	    return s3c2440_read_data();
	}	
}

/* 初始化NAND Flash */
void nand_init_ll(void)
{
	S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;
	S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;

#define TACLS   0
#define TWRPH0  3
#define TWRPH1  0

    /* 判断是S3C2410还是S3C2440 */
    if (isS3C2410)
    {
		/* 使能NAND Flash控制器,初始化ECC,禁止片选,设置时序 */
        s3c2410nand->NFCONF = (1<<15)|(1<<12)|(1<<11)|(TACLS<<8)|(TWRPH0<<4)|(TWRPH1<<0);
    }
    else
    {
		/* 设置时序 */
        s3c2440nand->NFCONF = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4);
        /* 使能NAND Flash控制器,禁止片选 */
        s3c2440nand->NFCONT = (1<<4)|(1<<1)|(1<<0);
    }

	/* 复位NAND Flash */
	nand_reset();
}


/* 读函数 */
void nand_read_ll(unsigned char *buf,int size)
{
    int i,j;
    
    if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK)) {
        return ;    /* 地址或长度不对齐 */
    }

    /* 选中芯片 */
    nand_select_chip();

    for(i=start_addr; i < (start_addr + size);) {
      /* 发出READ0命令 */
      write_cmd(0);

      /* Write Address */
      write_addr(i);
      wait_idle();

      for(j=0; j < NAND_SECTOR_SIZE; j++,i++) {
          *buf = read_data();
          buf++;
      }
    }

    /* 取消片选信号 */
    nand_deselect_chip();
    
    return ;
}


/* 读函数 
  * Large Page
  */
void nand_read_ll_lp(unsigned char *buf,j;
    
    if ((start_addr & NAND_BLOCK_MASK_LP) || (size & NAND_BLOCK_MASK_LP)) {
        return ;    /* 地址或长度不对齐 */
    }

    /* 选中芯片 */
    nand_select_chip();

    for(i=start_addr; i < (start_addr + size);) {
      /* 发出READ0命令 */
      write_cmd(0);

      /* Write Address */
      write_addr_lp(i);
	  write_cmd(0x30);
      wait_idle();

      for(j=0; j < NAND_SECTOR_SIZE_LP; j++,i++) {
          *buf = read_data();
          buf++;
      }
    }

    /* 取消片选信号 */
    nand_deselect_chip();
    
    return ;
}

int bBootFrmNORFlash(void)
{
    volatile unsigned int *pdw = (volatile unsigned int *)0;
    unsigned int dwVal;
    
    /*
     * 无论是从NOR Flash还是从NAND Flash启动，
     * 地址0处为指令"b	Reset",机器码为0xEA00000B，
     * 对于从NAND Flash启动的情况，其开始4KB的代码会复制到CPU内部4K内存中，
     * 对于从NOR Flash启动的情况，NOR Flash的开始地址即为0。
     * 对于NOR Flash，必须通过一定的命令序列才能写数据，
     * 所以可以根据这点差别来分辨是从NAND Flash还是NOR Flash启动:
     * 向地址0写入一个数据，然后读出来，如果没有改变的话就是NOR Flash
     */

    dwVal = *pdw;       
    *pdw = 0x12345678;
    if (*pdw != 0x12345678)
    {
        return 1;
    }
    else
    {
        *pdw = dwVal;
        return 0;
    }
}

int CopyCode2Ram(unsigned long start_addr,unsigned char *buf,int size)
{
    unsigned int *pdwDest;
    unsigned int *pdwSrc;
    int i;

    if (bBootFrmNORFlash())
    {
        pdwDest = (unsigned int *)buf;
        pdwSrc  = (unsigned int *)start_addr;
        /* 从 NOR Flash启动 */
        for (i = 0; i < size / 4; i++)
        {
            pdwDest[i] = pdwSrc[i];
        }
        return 0;
    }
    else
    {
        /* 初始化NAND Flash */
		nand_init_ll();
        /* 从 NAND Flash启动 */
        nand_read_ll_lp(buf,start_addr,(size + NAND_BLOCK_MASK_LP)&~(NAND_BLOCK_MASK_LP));
		return 0;
    }
}
make clean

make?

然后烧写到nandflash启动。

（编辑：李大同）

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