Parse how to write flash in uefi shell.

Step:

1.     Enable

2.     Read

3.     Write

4.     Disable

FI_GUID gEfiSFlashProtocolGuid = FLASH_PROTOCOL_GUID;

FLASH_PROTOCOL*  pFlashProtocol;

EFI_PHYSICAL_ADDRESS        Flash4GBMapStart;

EFI_STATUS   Status;

UINT8        *StrBuffer;

Status = pBootServices->LocateProtocol( &gEfiSFlashProtocolGuid, NULL, &pFlashProtocol);

Status = pBootServices->AllocatePool(//start: allocate mem  check point hear

             EfiBootServicesData,

             sizeof(UINT8) * FLASH_BLOCK_SIZE,

             (VOID*)&StrBuffer);

if (EFI_ERROR(Status) || StrBuffer == NULL) {

        error code here…..

      }

MemSet(StrBuffer, (sizeof(UINT8) * FLASH_BLOCK_SIZE), );

Flash4GBMapStart = 0xFFFFFFFF - FLASH_SIZE + ;

//Enable DeviceWrite to read real Flash address, not memory mapping.

Status = pFlashProtocol->DeviceWriteEnable();//step1. enable

 if (EFI_ERROR(Status)) {

               error code here…..

 }

 Status = pFlashProtocol->Read(//step2. Read

                   (VOID*)Flash4GBMapStart,

                   FLASH_BLOCK_SIZE,

                   (VOID*)StrBuffer);

 *(StrBuffer+PcieLaneSettingAddr) = PcieLaneSetting;

Status = pFlashProtocol->Write(//step3. Update or write

 (VOID*)Flash4GBMapStart,

FLASH_BLOCK_SIZE,

 (VOID*)StrBuffer);

 pFlashProtocol->DeviceWriteDisable();  //step4. Disable

pBootServices->FreePool(StrBuffer);//end: free memory