norflash

以uboot2010.06为例解说norflash工作原理

2018-11-09
24次浏览

根据根目录makefile文件得知系统从start.S启动,在start.S里面看到函数跳转到start_armboot 里面调用了flash_init ()初始化,这里我们知道是对flash进行初始化。那么这个函数在哪里呢? 在board/samsung/smdk2440/flash.c下。于是我们在这个flash.c文件下分析flash

              我用的norflash是EN29LV160AB这个型号,和uboot源码里有些出入 所以在分析的过程中我们适当更改部分配置

先从宏定义开始看

#define FLASH_BANK_SIZE PHYS_FLASH_SIZE    //从字面分析 应该是定义flashBANK空间  我们的flash是2M的 所有后面的PHYS_FLASH_SIZE   = 0x20000000

#define MAIN_SECT_SIZE  0x8000 /* 32 KB */     //定义了主要的sect(扇区)大小,看EN29LV手册  我们总共有35个扇区 31个大小为32K

flash_info_t flash_info[CONFIG_SYS_MAX_FLASH_BANKS];

//其中CONFIG_SYS_MAX_FLASH_BANKS在smdk2410.h里定义#define CONFIG_SYS_MAX_FLASH_SECT (35) /* max number of sectors on one chip */


#define CMD_READ_ARRAY  0x000000F0  //下面几个宏定义在EN29LV里面都有说明 是常用的命令数据
#define CMD_UNLOCK1  0x000000AA
#define CMD_UNLOCK2  0x00000055
#define CMD_ERASE_SETUP  0x00000080
#define CMD_ERASE_CONFIRM 0x00000030
#define CMD_PROGRAM  0x000000A0
#define CMD_UNLOCK_BYPASS 0x00000020

//以下两个宏为EN29LV手册中提到的命令写入的地址一个是0x555 一个是2AA 至于为什么左移一位,是设计时 norflash的地址A0通常接ARM芯片地址的A1为 所以地址左移

#define MEM_FLASH_ADDR1  (*(volatile u16 *)(CONFIG_SYS_FLASH_BASE + (0x00000555 << 1)))
#define MEM_FLASH_ADDR2  (*(volatile u16 *)(CONFIG_SYS_FLASH_BASE + (0x000002AA << 1)))

#define BIT_ERASE_DONE  0x00000080
#define BIT_RDY_MASK  0x00000080
#define BIT_PROGRAM_ERROR 0x00000020
#define BIT_TIMEOUT  0x80000000 /* our flag */

#define READY 1
#define ERR   2
#define TMO   4

//搞清楚了上面的宏定义 再看下面的几个函数就好理解多了。。。。

ulong flash_init (void)      //flash初始化函数
{
 int i, j;
 ulong size = 0;

 for (i = 0; i < CONFIG_SYS_MAX_FLASH_BANKS; i++) {       //对BANK区初始化 一般只用到BANK0 所以这里只循环一次  这里是通用写法
  ulong flashbase = 0;

  flash_info[i].flash_id =         //根据flash型号 赋予flashid号 我们也可以自定义
#if defined(CONFIG_AMD_LV400)
   (AMD_MANUFACT & FLASH_VENDMASK) |
   (AMD_ID_LV400B & FLASH_TYPEMASK);
#elif defined(CONFIG_AMD_LV800)
   (AMD_MANUFACT & FLASH_VENDMASK) |
   (AMD_ID_LV800B & FLASH_TYPEMASK);
#else
#error "Unknown flash configured"
#endif
   flash_info[i].size = FLASH_BANK_SIZE;              //赋值当前BANK中flash占用大小  这里我们的norflash才2M  arm9一个bank有128M 我们只占用了2M

  flash_info[i].sector_count = CONFIG_SYS_MAX_FLASH_SECT;               //有多少个扇区 前面提到 总共35个
  memset (flash_info[i].protect, 0, CONFIG_SYS_MAX_FLASH_SECT);    //受保护的扇区
  if (i == 0)
   flashbase = PHYS_FLASH_1;                                 //flash起始地址  = 0x00000000
  else
   panic ("configured too many flash banks!\n");
for (j = 0; j < flash_info[i].sector_count; j++) 
{
    if (j <= 3) 
   {
        /* 1st one is 8 KB */
       if (j == 0) 
      {
             flash_info[i].start[j] = flashbase + 0;       //由EN29LV手册 第一个扇区大小为8K  起始地址为0x00000000
      }

      /* 2nd and 3rd are both 4 KB */
      if ((j == 1) || (j == 2)) 
     {
           flash_info[i].start[j] = flashbase + 0x2000 + (j - 1) * 0x1000;    //第二个和第三个扇区大小为4K 起始地址紧跟在8K后
     }

     /* 4th 16 KB */
     if (j == 3) 
    {
           flash_info[i].start[j] = flashbase + 0x4000;
     }
 } 
 else 
 {
       flash_info[i].start[j] = flashbase + (j - 3) * MAIN_SECT_SIZE;      //其余31个扇区皆为32K
 }
}
size += flash_info[i].size;       //获得整个flash的大小 2M

 flash_protect (FLAG_PROTECT_SET,
         CONFIG_SYS_FLASH_BASE,
         CONFIG_SYS_FLASH_BASE + monitor_flash_len - 1,
         &flash_info[0]);

 flash_protect (FLAG_PROTECT_SET,
         CONFIG_ENV_ADDR,
         CONFIG_ENV_ADDR + CONFIG_ENV_SIZE - 1, &flash_info[0]);

 return size;
}

int flash_erase (flash_info_t * info, int s_first, int s_last)    // flash擦除函数

{
 ushort result;
 int iflag, cflag, prot, sect;
 int rc = ERR_OK;
 int chip;

 /* first look for protection bits */

 if (info->flash_id == FLASH_UNKNOWN)
  return ERR_UNKNOWN_FLASH_TYPE;

 if ((s_first < 0) || (s_first > s_last)) {
  return ERR_INVAL;
 }

 if ((info->flash_id & FLASH_VENDMASK) !=
     (AMD_MANUFACT & FLASH_VENDMASK)) {
  return ERR_UNKNOWN_FLASH_VENDOR;
 }                      //以上都是一些验证信息 flash不对 提示错误

 prot = 0;
 for (sect = s_first; sect <= s_last; ++sect) {               //如果有受保护扇区 也擦除不成功
  if (info->protect[sect]) {
   prot++;
  }
 }
 if (prot)
  return ERR_PROTECTED;

 /*
  * Disable interrupts which might cause a timeout
  * here. Remember that our exception vectors are
  * at address 0 in the flash, and we don't want a
  * (ticker) exception to happen while the flash
  * chip is in programming mode.
  */
 cflag = icache_status ();
 icache_disable ();
 iflag = disable_interrupts ();

 /* Start erase on unprotected sectors */
 for (sect = s_first; sect <= s_last && !ctrlc (); sect++) {      //按扇区一个个擦除
  printf ("Erasing sector %2d ... ", sect);

  /* arm simple, non interrupt dependent timer */
  reset_timer_masked ();

  if (info->protect[sect] == 0) { /* not protected */
   vu_short *addr = (vu_short *) (info->start[sect]);            //从第一个扇区开始擦除

   MEM_FLASH_ADDR1 = CMD_UNLOCK1;                      //前面提到过 这些EN29LV手册里都有提示  就是往flash里写命令的格式
   MEM_FLASH_ADDR2 = CMD_UNLOCK2;
   MEM_FLASH_ADDR1 = CMD_ERASE_SETUP;

   MEM_FLASH_ADDR1 = CMD_UNLOCK1;
   MEM_FLASH_ADDR2 = CMD_UNLOCK2;
   *addr = CMD_ERASE_CONFIRM;

   /* wait until flash is ready */
   chip = 0;

   do {
    result = *addr;

    /* check timeout */
    if (get_timer_masked () >
        CONFIG_SYS_FLASH_ERASE_TOUT) {
     MEM_FLASH_ADDR1 = CMD_READ_ARRAY;
     chip = TMO;
     break;
    }

    if (!chip
        && (result & 0xFFFF) & BIT_ERASE_DONE)
     chip = READY;

    if (!chip
        && (result & 0xFFFF) & BIT_PROGRAM_ERROR)
     chip = ERR;

   } while (!chip);

   MEM_FLASH_ADDR1 = CMD_READ_ARRAY;

   if (chip == ERR) {
    rc = ERR_PROG_ERROR;
    goto outahere;
   }
   if (chip == TMO) {
    rc = ERR_TIMOUT;
    goto outahere;
   }

   printf ("ok.\n");
  } else { /* it was protected */

   printf ("protected!\n");
  }
 }

 if (ctrlc ())
  printf ("User Interrupt!\n");

      outahere:
 /* allow flash to settle - wait 10 ms */
 udelay_masked (10000);

 if (iflag)
  enable_interrupts ();

 if (cflag)
  icache_enable ();

 return rc;
}

static int write_hword (flash_info_t * info, ulong dest, ushort data)    //向flash里写一个半字 16bit
{
 vu_short *addr = (vu_short *) dest;                         //dest表示flash里的地址
 ushort result;
 int rc = ERR_OK;
 int cflag, iflag;
 int chip;

 /*
  * Check if Flash is (sufficiently) erased
  */
 result = *addr;
 if ((result & data) != data)                  //检查flash是否擦除 擦除后就全是FFFF了
  return ERR_NOT_ERASED;


 /*
  * Disable interrupts which might cause a timeout
  * here. Remember that our exception vectors are
  * at address 0 in the flash, and we don't want a
  * (ticker) exception to happen while the flash
  * chip is in programming mode.
  */
 cflag = icache_status ();
 icache_disable ();
 iflag = disable_interrupts ();

 MEM_FLASH_ADDR1 = CMD_UNLOCK1;
 MEM_FLASH_ADDR2 = CMD_UNLOCK2;
 MEM_FLASH_ADDR1 = CMD_UNLOCK_BYPASS;
 *addr = CMD_PROGRAM;                       //手册里的写半字命令
 *addr = data;

 /* arm simple, non interrupt dependent timer */
 reset_timer_masked ();

 /* wait until flash is ready */
 chip = 0;
 do {
  result = *addr;

  /* check timeout */
  if (get_timer_masked () > CONFIG_SYS_FLASH_ERASE_TOUT) {
   chip = ERR | TMO;
   break;
  }
  if (!chip && ((result & 0x80) == (data & 0x80)))
   chip = READY;

  if (!chip && ((result & 0xFFFF) & BIT_PROGRAM_ERROR)) {
   result = *addr;

   if ((result & 0x80) == (data & 0x80))
    chip = READY;
   else
    chip = ERR;
  }

 } while (!chip);

 *addr = CMD_READ_ARRAY;

 if (chip == ERR || *addr != data)
  rc = ERR_PROG_ERROR;

 if (iflag)
  enable_interrupts ();

 if (cflag)
  icache_enable ();

 return rc;
}

/*-----------------------------------------------------------------------
 * Copy memory to flash.
 */

int write_buff (flash_info_t * info, uchar * src, ulong addr, ulong cnt)                  //flash写   会调用上面的写hword命令  这个是写一片
{
 ulong cp, wp;
 int l;
 int i, rc;
 ushort data;

 wp = (addr & ~1); /* get lower word aligned address */

 /*
  * handle unaligned start bytes
  */
 if ((l = addr - wp) != 0) {
  data = 0;
  for (i = 0, cp = wp; i < l; ++i, ++cp) {
   data = (data >> 8) | (*(uchar *) cp << 8);
  }
  for (; i < 2 && cnt > 0; ++i) {
   data = (data >> 8) | (*src++ << 8);
   --cnt;
   ++cp;
  }
  for (; cnt == 0 && i < 2; ++i, ++cp) {
   data = (data >> 8) | (*(uchar *) cp << 8);
  }

  if ((rc = write_hword (info, wp, data)) != 0) {
   return (rc);
  }
  wp += 2;
 }

 /*
  * handle word aligned part
  */
 while (cnt >= 2) {
  data = *((vu_short *) src);
  if ((rc = write_hword (info, wp, data)) != 0) {
   return (rc);
  }
  src += 2;
  wp += 2;
  cnt -= 2;
 }

 if (cnt == 0) {
  return ERR_OK;
 }

 /*
  * handle unaligned tail bytes
  */
 data = 0;
 for (i = 0, cp = wp; i < 2 && cnt > 0; ++i, ++cp) {
  data = (data >> 8) | (*src++ << 8);
  --cnt;
 }
 for (; i < 2; ++i, ++cp) {
  data = (data >> 8) | (*(uchar *) cp << 8);
 }

 return write_hword (info, wp, data);
}

 

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