wince FAL+FMD 分析（修改）

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本文介绍了Wince系统中FAL+FMD模块的工作原理。重点解析了设备驱动的数据结构DEVICE及其初始化过程，FMDInterface接口的获取及功能，包括设备初始化、信息获取等关键步骤。

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wince FAL+FMD的简单分析

creator

sz111@126.com

http://hi.baidu.com/guly699 小改

1.首先弄清楚FAL中的设备驱动，物理设备数据类型如下：

typedef struct _DEVICE

{

DWORD dwID;

PVOID hFMD;

PVOID hFMDHook;

} DEVICE , *PDEVICE;

有一个公共变量g_pDevice来保存这个。pDevice指向g_pDevice（如在函数 DWORD DSK_Init(DWORD dwContext) ；中 PDEVICE pDevice = g_pDevice;）

2.在DSK_Init初始化化中，会通过GetFMDInterface(pDevice)函数获得设备的FMD。

VOID GetFMDInterface(PDEVICE pDevice)

{

FMD.cbSize = sizeof(FMDInterface);

// query FMD intrface from the FMD

FMD.pOEMIoControl = FMD_OEMIoControl;

if (!FMD_OEMIoControl (IOCTL_FMD_GET_INTERFACE, NULL, 0, (PBYTE)&FMD, sizeof(FMDInterface), NULL))

{

// FMD does not support IOCTL_FMD_GET_INTERFACE, so build the FMDInterface

// structure using the legacy FMD functions

FMD.pInit = FMD_Init;

FMD.pDeInit = FMD_Deinit;

FMD.pGetInfo = FMD_GetInfo;

FMD.pGetBlockStatus = FMD_GetBlockStatus;

FMD.pSetBlockStatus = FMD_SetBlockStatus;

FMD.pReadSector = FMD_ReadSector;

FMD.pWriteSector = FMD_WriteSector;

FMD.pEraseBlock = FMD_EraseBlock;

FMD.pPowerUp = FMD_PowerUp;

FMD.pPowerDown = FMD_PowerDown;

}

// query hook library in case any FMD functions need to be shimmed

pDevice->hFMDHook = FMDHOOK_HookInterface(&FMD);

}

typedef struct _FMDInterface
{
    DWORD cbSize;
    PFN_INIT pInit;
    PFN_DEINIT pDeInit;
    PFN_GETINFO pGetInfo;
    PFN_GETBLOCKSTATUS pGetBlockStatus;
    PFN_SETBLOCKSTATUS pSetBlockStatus;
    PFN_READSECTOR pReadSector;
    PFN_WRITESECTOR pWriteSector;
    PFN_ERASEBLOCK pEraseBlock;
    PFN_POWERUP pPowerUp;
    PFN_POWERDOWN pPowerDown;
    PFN_GETPHYSSECTORADDR pGetPhysSectorAddr;
    PFN_GETINFOEX pGetInfoEx;
    PFN_OEMIOCONTROL pOEMIoControl;

} FMDInterface, *PFMDInterface;

其中FMD_OEMIoControl是在Fmd.cpp中定义的（我的BSP中在文件Fmd_readonly.cpp 和Fmd_writable.cpp中也有定义，不知为什么？希望高人解答下）。通过这个函数把msflash.dll和nandflash.dll联系起来。

通过它获得FMD，是一个函数指针接口，以后就通过FMD来执行FMD中的实际函数了。

BOOL FMD_OEMIoControl(DWORD dwIoControlCode, PBYTE pInBuf, DWORD nInBufSize, PBYTE pOutBuf, DWORD nOutBufSize, PDWORD pBytesReturned)

{

switch(dwIoControlCode)

{

case IOCTL_FMD_GET_INTERFACE:

{

RETAILMSG(1, (TEXT("[FMD] FMD_OEMIoControl() : IOCTL_FMD_GET_INTERFACE/r/n")));

if (!pOutBuf || nOutBufSize < sizeof(FMDInterface))

{

DEBUGMSG(1, (TEXT("FMD_OEMIoControl: IOCTL_FMD_GET_INTERFACE bad parameter(s)./r/n")));

return(FALSE);

}

PFMDInterface pInterface = (PFMDInterface)pOutBuf;

pInterface->cbSize = sizeof(FMDInterface);

pInterface->pInit = FMD_Init;

pInterface->pDeInit = FMD_Deinit;

pInterface->pGetInfo = FMD_GetInfo;

pInterface->pGetInfoEx = NULL; //FMD_GetInfoEx;

pInterface->pGetBlockStatus = FMD_GetBlockStatus;

pInterface->pSetBlockStatus = FMD_SetBlockStatus;

pInterface->pReadSector = FMD_ReadSector;

pInterface->pWriteSector = FMD_WriteSector;

pInterface->pEraseBlock = FMD_EraseBlock;

pInterface->pPowerUp = FMD_PowerUp;

pInterface->pPowerDown = FMD_PowerDown;

pInterface->pGetPhysSectorAddr = NULL;

break;

}

.....

}

3.获得FMD之后，首先调用FMD.pInit，对FMD设备进行初始化。主要是控制器的配置，读ID得到nandflash的容量，

等信息。

4.调用FMD.pGetInfo(&oldFlashInfo)获得nandflash的信息。最终也是调用BOOL FMD_GetInfo(PFlashInfo pFlashInfo)

pFlashInfo->dwNumBlocks = NUM_OF_BLOCKS;

pFlashInfo->wSectorsPerBlock = PAGES_PER_BLOCK;

pFlashInfo->wDataBytesPerSector = NAND_SECTOR_SIZE;

pFlashInfo->dwBytesPerBlock = (PAGES_PER_BLOCK * NAND_SECTOR_SIZE);

把相关信息读到oldFlashInfo中。然后把相关数据写入公共变量g_pFlashMediaInfo

5.然后通过调用CalculateLogicalRange来统计nandflash的区域大小和可以用的block

BOOL CalculateLogicalRange(PFlashRegion pRegion)

{

DWORD dwBlockID;

DWORD dwNumLogicalBlocks = 0;

for (dwBlockID = pRegion->dwStartPhysBlock; dwBlockID < pRegion->dwStartPhysBlock + pRegion->dwNumPhysBlocks; dwBlockID++)

{

DWORD dwStatus = FMD.pGetBlockStatus (dwBlockID);

if (!(dwStatus & (BLOCK_STATUS_RESERVED | BLOCK_STATUS_BAD)))

{

dwNumLogicalBlocks++;

}

//pRegion->dwCompactBlocks=MINIMUM_FLASH_BLOCKS_TO_RESERVE最少的block为2，如果wince发现少于2个block的可用块，就会返回error。

if (dwNumLogicalBlocks <= pRegion->dwCompactBlocks)

{

ReportError((TEXT("FLASHDRV.DLL:CalculateLogicalRange() - Invalid number of logical blocks %d/r/n"), dwNumLogicalBlocks));

return FALSE;

}

// Account for compaction blocks

dwNumLogicalBlocks -= pRegion->dwCompactBlocks;

pRegion->dwNumLogicalBlocks = dwNumLogicalBlocks;

return TRUE;

}

最终也是调用FMD_GetBlockStatus函数。