一、背景

1.1 硬件驅動層

工作也有幾年了，越來越覺得有必要做一個類似于LINUX的硬件驅動層，可以屏蔽所有硬件差異，再做新的項目，需要更改主控或者外設時，只需要更改相關的芯片支持包，讓我們更加專注于業務邏輯層的開發。

1.2 目標

RTTHREAD已經有現成的相關軟件框架，到時候可以借鑒一下，目前還是想自己寫代碼實現一遍以下的東西，只有真正做起來的才會發現問題，才會有進步的可能:

bootloader+
hardware_driver_layer+
fatfs+
usb host，usb device+
lcd+touch+lvgl+
freertos(rtthread)+
memory_manage+
(nandflash or norflash)+(psramor+sdram)+
script(java,lua,python,jerryscript)+
openharmony_ui_kit_ace_lite

二、目標狀態

目前已經實現了

bootloader+
fatfs+

usb device(usb mass storage)+
script(java)

下一個目標是lcd+touch+lvgl

三、SPI FLASH(NOR FLASH)

nor flash操作起來非常方便，不需要關系nand flash的虛擬地址映射、壞塊管理、ECC等問題。

3.1 w25q128

w25q128是winbond公司的，顧名思義有128Mbit容量，也就是16M字節大小，每頁有256字節，每個扇區有4096字節，每個塊有64K，每次可擦除一個扇區字節大小。

3.2 驅動程序
這里使用的是spi2作為通信接口

#include "stdio.h"


#include "common.h"
#include "stm32_kernel.h"
#include "stm32f10x_spi.h"
#include "stm32_spi.h"    
#include "deviceaccess_spi.h"    
#include "deviceaccess_gpio.h"    


#define W25Q80   0XEF13   
#define W25Q16   0XEF14
#define W25Q32   0XEF15
#define W25Q64   0XEF16
#define W25Q128  0XEF17


////////////////////////////////////////////////////////////////////////////

//指令表
#define W25X_WriteEnable    0x06 
#define W25X_WriteDisable    0x04 
#define W25X_ReadStatusReg    0x05 
#define W25X_WriteStatusReg    0x01 
#define W25X_ReadData      0x03 
#define W25X_FastReadData    0x0B 
#define W25X_FastReadDual    0x3B 
#define W25X_PageProgram    0x02 
#define W25X_BlockErase      0xD8 
#define W25X_SectorErase    0x20 
#define W25X_ChipErase      0xC7 
#define W25X_PowerDown      0xB9 
#define W25X_ReleasePowerDown  0xAB 
#define W25X_DeviceID      0xAB 
#define W25X_ManufactDeviceID  0x90 
#define W25X_JedecDeviceID    0x9F 


void W25QXX_Init(void);
u16  W25QXX_ReadID(void);            //讀取FLASH ID
u8   W25QXX_ReadSR(void);            //讀取狀態寄存器 
void W25QXX_Write_SR(u8 sr);        //寫狀態寄存器
void W25QXX_Write_Enable(void);      //寫使能 
void W25QXX_Write_Disable(void);    //寫保護
void W25QXX_Write_NoCheck(u8* pBuffer,u32 WriteAddr,u16 NumByteToWrite);
void W25QXX_Read(u8* pBuffer,u32 ReadAddr,u16 NumByteToRead);   //讀取flash
void W25QXX_Write(u8* pBuffer,u32 WriteAddr,u16 NumByteToWrite);//寫入flash
void W25QXX_Erase_Chip(void);          //整片擦除
void W25QXX_Erase_Sector(u32 Dst_Addr);  //扇區擦除
void W25QXX_Wait_Busy(void);             //等待空閑
void W25QXX_PowerDown(void);          //進入掉電模式
void W25QXX_WAKEUP(void);        //喚醒




//GPIOx = P*32+N
deviceaccess_spi_t spi_2 = {SPI_2,SPI_MODE_MASTER,8,SPI_BIT_ORDER_MSB,SPI_CPOL_H,SPI_CPHA_EDGE_2};
deviceaccess_gpio_t gpio_ext_flash_cs = {44,GPIO_MODE_PUSHPULL,GPIO_DIRECTION_OUTPUT,TRUE,NULL};


//#define  W25QXX_CS     PBout(12)      //W25QXX的片選信號


#define SPI_FLASH_CS_H  {g_deviceaccess_gpio_control(&gpio_ext_flash_cs,CMD_WRITE,TRUE);}
#define SPI_FLASH_CS_L  {g_deviceaccess_gpio_control(&gpio_ext_flash_cs,CMD_WRITE,FALSE);}


uint16_t get_flash_id = 0; 


u16 W25QXX_ReadID(void)
{
    u16 Temp = 0;    
    uint8_t set_tx_buffer[] = {0x90,0xFF,0xFF,0xFF};
    uint8_t set_rx_buffer[2];


    SPI_FLASH_CS_L;    


    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);//發送讀取ID命令      
    g_deviceaccess_spi_control(&spi_2,CMD_READ,set_rx_buffer,LENGTH_OF_ARRAY(set_rx_buffer),NULL);     
    Temp|=set_rx_buffer[0]< 8;  
    Temp|=set_rx_buffer[1];   
    SPI_FLASH_CS_H;            

    return Temp;
}


void W25QXX_Init(void)
{  
    g_deviceaccess_gpio_control(&gpio_ext_flash_cs,CMD_OPEN,NULL);

    SPI_FLASH_CS_H;        //SPI FLASH不選中


    g_deviceaccess_spi_control(&spi_2, CMD_OPEN,NULL,NULL,NULL);


    W25QXX_ReadID();//讀取FLASH ID.  
    get_flash_id=W25QXX_ReadID();//讀取FLASH ID.
    printf("get_flash_id=%xrn",get_flash_id);
}  


//讀取W25QXX的狀態寄存器
//BIT7  6   5   4   3   2   1   0
//SPR   RV  TB BP2 BP1 BP0 WEL BUSY
//SPR:默認0,狀態寄存器保護位,配合WP使用
//TB,BP2,BP1,BP0:FLASH區域寫保護設置
//WEL:寫使能鎖定
//BUSY:忙標記位(1,忙;0,空閑)
//默認:0x00
u8 W25QXX_ReadSR(void)   
{  
    u8 byte=0;   
    SPI_FLASH_CS_L;                            //使能器件   
    uint8_t set_tx_buffer[1] = {W25X_ReadStatusReg};
    uint8_t set_rx_buffer[1] = {0};
    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL); 
    g_deviceaccess_spi_control(&spi_2,CMD_READ,set_rx_buffer,LENGTH_OF_ARRAY(set_rx_buffer),NULL);
    byte=set_rx_buffer[0];          //讀取一個字節  
    SPI_FLASH_CS_H;                            //取消片選     
    return byte;   
} 
//寫W25QXX狀態寄存器
//只有SPR,TB,BP2,BP1,BP0(bit 7,5,4,3,2)可以寫!!!
void W25QXX_Write_SR(u8 sr)   
{   
    SPI_FLASH_CS_L;                            //使能器件   
    uint8_t set_tx_buffer[] = {W25X_WriteStatusReg,sr};
    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL); 
    SPI_FLASH_CS_H;                            //取消片選             
}   
//W25QXX寫使能  
//將WEL置位   
void W25QXX_Write_Enable(void)   
{
    SPI_FLASH_CS_L;                            //使能器件   
    uint8_t set_tx_buffer[1] = {W25X_WriteEnable};
    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);
    SPI_FLASH_CS_H;                             //取消片選             
} 
//W25QXX寫禁止  
//將WEL清零  
void W25QXX_Write_Disable(void)   
{  
    SPI_FLASH_CS_L;                            //使能器件   
    uint8_t set_tx_buffer[1] = {W25X_WriteDisable};
    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);
    SPI_FLASH_CS_H;                            //取消片選             
}     


//讀取SPI FLASH  
//在指定地址開始讀取指定長度的數據
//pBuffer:數據存儲區
//ReadAddr:開始讀取的地址(24bit)
//NumByteToRead:要讀取的字節數(最大65535)
void W25QXX_Read(u8* pBuffer,u32 ReadAddr,u16 NumByteToRead)   
{ 
    u16 i;                           
    SPI_FLASH_CS_L;                              //使能器件  

    uint8_t set_tx_buffer[] = {W25X_ReadData,(u8)((ReadAddr) >?>16),(u8)((ReadAddr) >?>8),(u8)ReadAddr};


    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);
    g_deviceaccess_spi_control(&spi_2,CMD_READ,pBuffer,NumByteToRead,NULL);

    SPI_FLASH_CS_H;                      
}  
//SPI在一頁(0~65535)內寫入少于256個字節的數據
//在指定地址開始寫入最大256字節的數據
//pBuffer:數據存儲區
//WriteAddr:開始寫入的地址(24bit)
//NumByteToWrite:要寫入的字節數(最大256),該數不應該超過該頁的剩余字節數!!!   
void W25QXX_Write_Page(u8* pBuffer,u32 WriteAddr,u16 NumByteToWrite)
{
    u16 i;  
    uint8_t set_tx_buffer[] = {W25X_PageProgram,(u8)((WriteAddr) >?>16),(u8)((WriteAddr) >?>8),(u8)(WriteAddr)};

    W25QXX_Write_Enable();                    //SET WEL 

    SPI_FLASH_CS_L;                              //使能器件   

    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);

    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,pBuffer,NumByteToWrite,NULL);

    SPI_FLASH_CS_H;                              //取消片選 
    W25QXX_Wait_Busy();                 //等待寫入結束
} 
//無檢驗寫SPI FLASH 
//必須確保所寫的地址范圍內的數據全部為0XFF,否則在非0XFF處寫入的數據將失敗!
//具有自動換頁功能 
//在指定地址開始寫入指定長度的數據,但是要確保地址不越界!
//pBuffer:數據存儲區
//WriteAddr:開始寫入的地址(24bit)
//NumByteToWrite:要寫入的字節數(最大65535)
//CHECK OK
void W25QXX_Write_NoCheck(u8* pBuffer,u32 WriteAddr,u16 NumByteToWrite)   
{             
  u16 pageremain;     
  pageremain=256-WriteAddr%256; //單頁剩余的字節數           
  if(NumByteToWrite<=pageremain)pageremain=NumByteToWrite;//不大于256個字節
  while(1)
  {     
    W25QXX_Write_Page(pBuffer,WriteAddr,pageremain);
    if(NumByteToWrite==pageremain)break;//寫入結束了
     else //NumByteToWrite >pageremain
    {
      pBuffer+=pageremain;
      WriteAddr+=pageremain;  


      NumByteToWrite-=pageremain;        //減去已經寫入了的字節數
      if(NumByteToWrite >256)pageremain=256; //一次可以寫入256個字節
      else pageremain=NumByteToWrite;     //不夠256個字節了
    }
  }      
} 
//寫SPI FLASH  
//在指定地址開始寫入指定長度的數據
//該函數帶擦除操作!
//pBuffer:數據存儲區
//WriteAddr:開始寫入的地址(24bit)            
//NumByteToWrite:要寫入的字節數(最大65535)   
u8 W25QXX_BUFFER[4096];     
void W25QXX_Write(u8* pBuffer,u32 WriteAddr,u16 NumByteToWrite)   
{ 
  u32 secpos;
  u16 secoff;
  u16 secremain;     
   u16 i;    
  u8 * W25QXX_BUF;    
     W25QXX_BUF=W25QXX_BUFFER;       
   secpos=WriteAddr/4096;//扇區地址  
  secoff=WriteAddr%4096;//在扇區內的偏移
  secremain=4096-secoff;//扇區剩余空間大小   
   //printf("ad:%X,nb:%Xrn",WriteAddr,NumByteToWrite);//測試用
   if(NumByteToWrite<=secremain)secremain=NumByteToWrite;//不大于4096個字節
  while(1) 
  {  
    W25QXX_Read(W25QXX_BUF,secpos*4096,4096);//讀出整個扇區的內容
    for(i=0;i< secremain;i++)//校驗數據
    {
      if(W25QXX_BUF[secoff+i]!=0XFF)break;//需要擦除      
    }
    if(i< secremain)//需要擦除
    {
      W25QXX_Erase_Sector(secpos);    //擦除這個扇區
      for(i=0;i< secremain;i++)         //復制
      {
        W25QXX_BUF[i+secoff]=pBuffer[i];    
      }
      W25QXX_Write_NoCheck(W25QXX_BUF,secpos*4096,4096);//寫入整個扇區  


    }else W25QXX_Write_NoCheck(pBuffer,WriteAddr,secremain);//寫已經擦除了的,直接寫入扇區剩余區間.            
    if(NumByteToWrite==secremain)break;//寫入結束了
    else//寫入未結束
    {
      secpos++;//扇區地址增1
      secoff=0;//偏移位置為0    


         pBuffer+=secremain;          //指針偏移
      WriteAddr+=secremain;        //寫地址偏移     
         NumByteToWrite-=secremain;      //字節數遞減
      if(NumByteToWrite >4096)secremain=4096;//下一個扇區還是寫不完
      else secremain=NumByteToWrite;    //下一個扇區可以寫完了
    }   
  };   
}
//擦除整個芯片      
//等待時間超長...
void W25QXX_Erase_Chip(void)   
{        
    uint8_t set_tx_buffer[1] = {W25X_ChipErase};
    W25QXX_Write_Enable();                      //SET WEL 
    W25QXX_Wait_Busy();   
    SPI_FLASH_CS_L;                              //使能器件   


    W25QXX_Write_Enable();                    //SET WEL 

    SPI_FLASH_CS_L;                              //使能器件   

    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);


    SPI_FLASH_CS_H;                              //取消片選            

    W25QXX_Wait_Busy();                  //等待芯片擦除結束
}   


//擦除一個扇區
//Dst_Addr:扇區地址 根據實際容量設置
//擦除一個山區的最少時間:150ms
void W25QXX_Erase_Sector(u32 Dst_Addr)   
{  
    uint8_t set_tx_buffer[] = {W25X_SectorErase,(u8)((Dst_Addr) >?>16),(u8)((Dst_Addr) >?>8),(u8)Dst_Addr};

  //監視falsh擦除情況,測試用   
    //printf("fe:%xrn",Dst_Addr);    
    Dst_Addr*=4096;
    W25QXX_Write_Enable();                    //SET WEL    
    W25QXX_Wait_Busy();   
    SPI_FLASH_CS_L;                              //使能器件   

    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);


    SPI_FLASH_CS_H;                              //取消片選             

    W25QXX_Wait_Busy();                  //等待擦除完成
}  


//等待空閑
void W25QXX_Wait_Busy(void)   
{   
  while((W25QXX_ReadSR()&0x01)==0x01);      // 等待BUSY位清空
}  


//進入掉電模式
void W25QXX_PowerDown(void)   
{ 
    uint8_t set_tx_buffer[] = {W25X_PowerDown};

    SPI_FLASH_CS_L;                                //使能器件   

    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);

    SPI_FLASH_CS_H;                              //取消片選             
    //delay_us(3);                               //等待TPD  
}   
//喚醒
void W25QXX_WAKEUP(void)   
{  
    uint8_t set_tx_buffer[] = {W25X_ReleasePowerDown};

    SPI_FLASH_CS_L;                              //使能器件   

    g_deviceaccess_spi_control(&spi_2,CMD_WRITE,set_tx_buffer,LENGTH_OF_ARRAY(set_tx_buffer),NULL);

    SPI_FLASH_CS_H;                              //取消片選             
    //delay_us(3);                              //等待TRES1
}

四、 FATFS

4.1 c源文件

這里就用到了2個c文件:diskio.c,ff.c
4.2 配置
打開ffconf.h頭文件，作以下更改

#define  _USE_LFN  0
#define  _MIN_SS    512
#define  _MAX_SS    4096

4.3 接口代碼

DSTATUS disk_initialize 
(
  BYTE pdrv        /* Physical drive nmuber to identify the drive */
)
{
  u8 res=0;      
  switch(pdrv)
  {
    case EX_FLASH://外部flash
      W25QXX_Init();
       break;
    default:
      res=1; 
  }     

  if(res)return  STA_NOINIT;

  else return 0; //初始化成功 
} 


DRESULT disk_read (
  BYTE pdrv,    /* Physical drive nmuber to identify the drive */
  BYTE *buff,    /* Data buffer to store read data */
  DWORD sector,  /* Sector address in LBA */
  UINT count    /* Number of sectors to read */
)
{
  u8 res=0; 
    if (!count)return RES_PARERR;//count不能等于0，否則返回參數錯誤        
  switch(pdrv)
  {
    case EX_FLASH://外部flash
      sector+=CONFIG_START_SECTOR;

      for(;count >0;count--)
      {
        W25QXX_Read(buff,sector*FLASH_SECTOR_SIZE,FLASH_SECTOR_SIZE);
        sector++;
        buff+=FLASH_SECTOR_SIZE;
      }
      res=0;
      break;
    default:
      res=1; 
  }
    if(res==0x00)return RES_OK;   
    else return RES_ERROR;     
}


DRESULT disk_write (
  BYTE pdrv,      /* Physical drive nmuber to identify the drive */
  const BYTE *buff,  /* Data to be written */
  DWORD sector,    /* Sector address in LBA */
  UINT count      /* Number of sectors to write */
)
{
  u8 res=0;  
    if (!count)return RES_PARERR;//count不能等于0，否則返回參數錯誤        
  switch(pdrv)
  {
    case EX_FLASH://外部flash
      sector+=CONFIG_START_SECTOR;

      SwData_DetFromFlash(sector*FLASH_SECTOR_SIZE,count*FLASH_SECTOR_SIZE);
      for(;count >0;count--)
      {                        
      //  W25QXX_Write((u8*)buff,sector*FLASH_SECTOR_SIZE,FLASH_SECTOR_SIZE);
        W25QXX_Write_NoCheck((u8*)buff,sector*FLASH_SECTOR_SIZE,FLASH_SECTOR_SIZE);
        sector++;
        buff+=FLASH_SECTOR_SIZE;
      }
      res=0;
      break;
    default:
      res=1; 
  }
    //處理返回值，將SPI_SD_driver.c的返回值轉成ff.c的返回值
    if(res == 0x00)return RES_OK;   
    else return RES_ERROR;  
}


DRESULT disk_ioctl (
  BYTE pdrv,    /* Physical drive nmuber (0..) */
  BYTE cmd,    /* Control code */
  void *buff    /* Buffer to send/receive control data */
)
{
DRESULT res;                         


      switch(cmd)
      {
        case CTRL_SYNC:
        res = RES_OK; 
            break;   
        case GET_SECTOR_SIZE:
            *(WORD*)buff = FLASH_SECTOR_SIZE;
            res = RES_OK;
            break;   
        case GET_BLOCK_SIZE:
            *(WORD*)buff = FLASH_BLOCK_SIZE;
            res = RES_OK;
            break;   
        case GET_SECTOR_COUNT:
            *(DWORD*)buff = FLASH_SECTOR_COUNT;
            res = RES_OK;
            break;
        default:
            res = RES_PARERR;
            break;
      }
    return res;
}

4.4 注意事項
返回給文件系統的扇區大小必須是flash實際的扇區大小，可以自定義文件系統的大小，
格式化文件系統時要選擇帶引導分區的類型即:res=f_mkfs("",0,4096):

寫操作時不應使用W25QXX_Write，而是先計算需要擦除的大小，來進行擦除再進行寫操作

#define FLASH_SECTOR_SIZE          4096    
#define FLASH_BLOCK_SIZE     16 
u16      FLASH_SECTOR_COUNT= 2696;

4.5 測試代碼

u8 exf_getfree(u8 *drv,u32 *total,u32 *free)
{
  FATFS *fs1;
  u8 res;
    u32 fre_clust=0, fre_sect=0, tot_sect=0;
    //得到磁盤信息及空閑簇數量
    res =(u32)f_getfree((const TCHAR*)drv, (DWORD*)&fre_clust, &fs1);
    if(res==0)
  {                         
      tot_sect=(fs1- >n_fatent-2)*fs1- >csize;  //得到總扇區數
      fre_sect=fre_clust*fs1- >csize;      //得到空閑扇區數     
#if _MAX_SS!=512                  //扇區大小不是512字節,則轉換為512字節
    tot_sect*=fs1- >ssize/512;
    fre_sect*=fs1- >ssize/512;
#endif    
    *total=tot_sect >?>1;  //單位為KB
    *free=fre_sect >?>1;  //單位為KB 
   }
  return res;
}




    res = f_mount(&temp_fs,"",1); 

    if(res!=FR_OK)//FLASH磁盤,FAT文件系統錯誤,重新格式化FLASH
    {
        printf("Flash Disk Formatting...");  //格式化FLASH

        W25QXX_Erase_Chip();

        res=f_mkfs("",0,4096);

        delay_ms(1000);
    }  


    while(exf_getfree("",&total,&free))  //得到SD卡的總容量和剩余容量
    {
      printf("EXTFLASH Fatfs Error!");
      delay_ms(200);       
    }  

    printf("FATFS OK!");   
    printf("SD Total Size:%dMB",total >?>10);   
    printf("SD  Free Size:%dMB",free >?>10);

    char *filepath = "1.txt";
    UINT br;


    open_result = f_mount(&temp_fs,"",1);


    open_result =f_open(&f_txt,(const TCHAR*)filepath,FA_CREATE_ALWAYS|FA_WRITE);


    if(open_result==FR_OK)
    {
        printf("open file okn");


        read_result=f_write(&f_txt,data,sizeof(data)/sizeof(data[0]),(UINT*)&br);


        if(read_result==FR_OK)
        {
            printf("write okn");
            printf("br=%dn",br);
        }


    f_close(&f_txt);


    open_result =f_open(&f_txt,(const TCHAR*)filepath,FA_READ);


    printf("open_result=%dn",open_result);


    if(open_result==FR_OK)
    {
        read_result=f_read(&f_txt,data_read,sizeof(data)/sizeof(data[0]),(UINT*)&br);


        printf("read_result=%dn",read_result);


        if(read_result==FR_OK)
        {
            int i = 0;


            printf("read okn");
            printf("br=%dn",br);


            for(i=0;i< sizeof(data_read)/sizeof(data_read[0]);i++)
            {
                printf("data_read[%d]=%cn",i,data_read[i]);
            }
        }


        f_close(&f_txt);
    }


    }
    else
    {
        printf("open_result=%dn",open_result);
    }

五、USB MASS STORAGE
5.1 上報磁盤數量
u8 Max_Lun =MAX_LUN;通過更愛MAX_LUN的定義來更改磁盤數量

uint8_t *Get_Max_Lun(uint16_t Length)
{
  if (Length == 0)
  {
    pInformation- >Ctrl_Info.Usb_wLength = LUN_DATA_LENGTH;
    return 0;
  }
  else
  {
    return((uint8_t*)(&Max_Lun));
  }
}

5.2 usb緩存大小定義
更改USB緩存大小為flash的實際扇區大小4K

在memory.c中定義Data_Bufferw為1024，也就是4096
u32 Data_Buffer[1024];

5.3 接口代碼

uint16_t MAL_Init(uint8_t lun)
{ 
  u16 Status=MAL_OK;   
  switch (lun)
  {
    case 0:         


      break;         
    case 1:         
      break;      
    default:
      return MAL_FAIL;
  }
  return Status;
}


uint16_t MAL_Write(uint8_t lun, uint64_t Memory_Offset, uint32_t *Writebuff, uint16_t Transfer_Length)
{
  u8 STA;
  switch (lun)    //這里,根據lun的值確定所要操作的磁盤
  {
    case 0:       //磁盤0為 SPI FLASH盤  
      STA=0;
      SwData_DetFromFlash(CONFIG_FATFS_START_ADDRESS+Memory_Offset,Transfer_Length);
        W25QXX_Write_NoCheck((u8*)Writebuff,CONFIG_FATFS_START_ADDRESS+Memory_Offset,Transfer_Length);
      break; 
    default:
      return MAL_FAIL;
  }
  if(STA!=0)return MAL_FAIL;
  return MAL_OK; 
}


uint16_t MAL_Read(uint8_t lun, uint64_t Memory_Offset, uint32_t *Readbuff, uint16_t Transfer_Length)
{
  u8 STA;
  switch (lun)    //這里,根據lun的值確定所要操作的磁盤
  {
    case 0:      //磁盤0為 SPI FLASH盤   
      STA=0;
      W25QXX_Read((u8*)Readbuff, CONFIG_FATFS_START_ADDRESS+Memory_Offset, Transfer_Length);         
      break;            
    default:
      return MAL_FAIL;
  }
  if(STA!=0)return MAL_FAIL;
  return MAL_OK;
}


uint16_t MAL_GetStatus (uint8_t lun)
{
    switch(lun)
    {
    case 0:
      return MAL_OK;
    case 1:
      return MAL_OK; 
    default:
      return MAL_FAIL;
    } 
}

5. 4 初始化代碼

Mass_Memory_Size[0]=1024*1024*10;  //前12M字節
    Mass_Block_Size[0] =4096;      //設置SPI FLASH的操作扇區大小為512
    Mass_Block_Count[0]=Mass_Memory_Size[0]/Mass_Block_Size[0];      

     delay_ms(1800);
    usb_port_set(0);   //USB先斷開
    delay_ms(300);
    usb_port_set(1);  //USB再次連接     
    //USB配置
    USB_Interrupts_Config();    
    Set_USBClock();   
    USB_Init();      
    delay_ms(1800);

六、遇到的坑

6.1 ID信息

可能是W25Q128的硬件有問題，在上電時需要讀兩次才能讀到ID信息，但ID信息與數據手冊上的對不上，可能IC是盜版的吧。

6.2 文件系統格式化失敗

在格式化時最好加上整個flash或者指定大小的擦除操作再進行格式化

6.3 文件系統讀寫失敗

在進行讀操作時，可能是出現讀到的數據全是錯的問題，后來排查發現是W25QXX_Write的問題，更改為先查出再寫后問題得到解決。

6.4 文件系統讀不到正確的容量大小

將最大扇區和返回扇區大小更改為4096
6.5 USB MASS STORAGE打不開磁盤

將USB緩存區更改為總大小為flash實際扇區大小4096，在USB初始化前設置好扇區大小為實際的flash扇區大小，扇區數量，磁盤容量更改為實際需要

6.6 燒錄文件系統到外部FLASH的方法
6.6.1 制作鏡像文件

使用DiskGenius工具創建虛擬磁盤鏡像文件，由于現有的磁盤分區工具只兼容512字節扇區的硬件，所以在文件系統所使用的寫FLASH接口需要使用帶檢查的寫操作，也就是在寫的時候不影響其他扇區的數據，這樣的話就可以兼容FATFS最大扇區為512字節的配置
6.6.2 燒錄鏡像文件到外部FLASH

6.7 加速FLASH訪問

使用DMA方式進行SPI的讀寫

if(send_ptr != RT_NULL)
    {
        volatile uint8_t dummy_data;
        dma_init_type dma_init_struct;
        dma_reset(DMA2_CHANNEL5);
        dma_reset(DMA2_CHANNEL4);


        dma_default_para_init(&dma_init_struct);
        dma_init_struct.buffer_size = size;
        dma_init_struct.direction = DMA_DIR_PERIPHERAL_TO_MEMORY;
        dma_init_struct.memory_base_addr = (uint32_t)&dummy_data;
        dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_BYTE;
        dma_init_struct.memory_inc_enable = FALSE;
        dma_init_struct.peripheral_base_addr = (uint32_t)(&spi_instance- >config- >spi_x- >dt);
        dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_BYTE;
        dma_init_struct.peripheral_inc_enable = FALSE;
        dma_init_struct.priority = DMA_PRIORITY_VERY_HIGH;
        dma_init_struct.loop_mode_enable = FALSE;
        dma_init(DMA2_CHANNEL4, &dma_init_struct);

        dma_init_struct.buffer_size = message- >length;
        dma_init_struct.direction = DMA_DIR_MEMORY_TO_PERIPHERAL;
        dma_init_struct.memory_base_addr = (uint32_t)send_ptr;
        dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_BYTE;
        dma_init_struct.memory_inc_enable = TRUE;
        dma_init_struct.peripheral_base_addr = (uint32_t)(&spi_instance- >config- >spi_x- >dt);
        dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_BYTE;
        dma_init_struct.peripheral_inc_enable = FALSE;
        dma_init_struct.priority = DMA_PRIORITY_VERY_HIGH;
        dma_init_struct.loop_mode_enable = FALSE;
        dma_init(DMA2_CHANNEL5, &dma_init_struct);


        spi_i2s_dma_transmitter_enable(spi_instance- >config- >spi_x, TRUE);
        spi_i2s_dma_receiver_enable(spi_instance- >config- >spi_x, TRUE);


        dma_channel_enable(DMA2_CHANNEL4, TRUE);
        dma_channel_enable(DMA2_CHANNEL5, TRUE);


        while(dma_flag_get(DMA2_FDT4_FLAG) == RESET);
        dma_flag_clear(DMA2_FDT4_FLAG);


        dma_channel_enable(DMA2_CHANNEL5, FALSE);
        dma_channel_enable(DMA2_CHANNEL4, FALSE);


        spi_i2s_dma_receiver_enable(spi_instance- >config- >spi_x, FALSE);
        spi_i2s_dma_transmitter_enable(spi_instance- >config- >spi_x, FALSE);
    }
    else if(recv_ptr != RT_NULL)
    {
        uint8_t write_value = 0xA5;
        dma_init_type dma_init_struct;
        dma_reset(DMA2_CHANNEL5);
        dma_reset(DMA2_CHANNEL4);


        dma_default_para_init(&dma_init_struct);
        dma_init_struct.buffer_size = size;
        dma_init_struct.direction = DMA_DIR_MEMORY_TO_PERIPHERAL;
        dma_init_struct.memory_base_addr = (uint32_t)&write_value;
        dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_BYTE;
        dma_init_struct.memory_inc_enable = FALSE;
        dma_init_struct.peripheral_base_addr = (uint32_t)(&spi_instance- >config- >spi_x- >dt);
        dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_BYTE;
        dma_init_struct.peripheral_inc_enable = FALSE;
        dma_init_struct.priority = DMA_PRIORITY_VERY_HIGH;
        dma_init_struct.loop_mode_enable = FALSE;
        dma_init(DMA2_CHANNEL5, &dma_init_struct);


        dma_init_struct.buffer_size = size;
        dma_init_struct.direction = DMA_DIR_PERIPHERAL_TO_MEMORY;
        dma_init_struct.memory_base_addr = (uint32_t)recv_ptr;
        dma_init_struct.memory_data_width = DMA_MEMORY_DATA_WIDTH_BYTE;
        dma_init_struct.memory_inc_enable = TRUE;
        dma_init_struct.peripheral_base_addr = (uint32_t)(&spi_instance- >config- >spi_x- >dt);
        dma_init_struct.peripheral_data_width = DMA_PERIPHERAL_DATA_WIDTH_BYTE;
        dma_init_struct.peripheral_inc_enable = FALSE;
        dma_init_struct.priority = DMA_PRIORITY_VERY_HIGH;
        dma_init_struct.loop_mode_enable = FALSE;
        dma_init(DMA2_CHANNEL4, &dma_init_struct);
        //
        spi_i2s_dma_transmitter_enable(spi_instance- >config- >spi_x, TRUE);
        spi_i2s_dma_receiver_enable(spi_instance- >config- >spi_x, TRUE);
        //
        dma_channel_enable(DMA2_CHANNEL4, TRUE);
        dma_channel_enable(DMA2_CHANNEL5, TRUE);


        while(dma_flag_get(DMA2_FDT4_FLAG) == RESET);
        dma_flag_clear(DMA2_FDT4_FLAG);


        dma_channel_enable(DMA2_CHANNEL5, FALSE);
        dma_channel_enable(DMA2_CHANNEL4, FALSE);


        spi_i2s_dma_receiver_enable(spi_instance- >config- >spi_x, FALSE);
        spi_i2s_dma_transmitter_enable(spi_instance- >config- >spi_x, FALSE);
    }
#endif