ArmPlatformPkg/NorFlashDxe: Optimise FVB protocol

- Only read what needs reading, don't read the whole block.
- Don't write back buffers containing no data after an erase.
- Reduce number of NOR erases when writing data. Only erase the block
  when required.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Harry Liebel <Harry.Liebel@arm.com>
Reviewed-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15500 6f19259b-4bc3-4df7-8a09-765794883524

ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe.c

@@ -586,6 +586,7 @@ NorFlashWriteSingleBlock (
   UINTN         BuffersInBlock;
   UINTN         RemainingWords;
   EFI_TPL       OriginalTPL;
+  UINTN         Cnt;
 
   Status = EFI_SUCCESS;
 
@@ -619,14 +620,23 @@ NorFlashWriteSingleBlock (
     BuffersInBlock = (UINTN)(BlockSizeInWords * 4) / P30_MAX_BUFFER_SIZE_IN_BYTES;
 
     // Then feed each buffer chunk to the NOR Flash
+    // If a buffer does not contain any data, don't write it.
     for(BufferIndex=0;
          BufferIndex < BuffersInBlock;
          BufferIndex++, WordAddress += P30_MAX_BUFFER_SIZE_IN_BYTES, DataBuffer += P30_MAX_BUFFER_SIZE_IN_WORDS
       ) {
-      Status = NorFlashWriteBuffer (Instance, WordAddress, P30_MAX_BUFFER_SIZE_IN_BYTES, DataBuffer);
+      // Check the buffer to see if it contains any data (not set all 1s).
+      for (Cnt = 0; Cnt < P30_MAX_BUFFER_SIZE_IN_WORDS; Cnt++) {
+        if (~DataBuffer[Cnt] != 0 ) {
+          // Some data found, write the buffer.
+          Status = NorFlashWriteBuffer (Instance, WordAddress, P30_MAX_BUFFER_SIZE_IN_BYTES,
+                                        DataBuffer);
           if (EFI_ERROR(Status)) {
             goto EXIT;
           }
+          break;
+        }
+      }
     }
 
     // Finally, finish off any remaining words that are less than the maximum size of the buffer
@@ -784,6 +794,57 @@ NorFlashReadBlocks (
   return EFI_SUCCESS;
 }
 
+EFI_STATUS
+NorFlashRead (
+  IN NOR_FLASH_INSTANCE   *Instance,
+  IN EFI_LBA              Lba,
+  IN UINTN                Offset,
+  IN UINTN                BufferSizeInBytes,
+  OUT VOID                *Buffer
+  )
+{
+  UINT32              NumBlocks;
+  UINTN               StartAddress;
+
+  // The buffer must be valid
+  if (Buffer == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  // Return if we have not any byte to read
+  if (BufferSizeInBytes == 0) {
+    return EFI_SUCCESS;
+  }
+
+  // All blocks must be within the device
+  NumBlocks = ((UINT32)BufferSizeInBytes) / Instance->Media.BlockSize ;
+
+  if ((Lba + NumBlocks) > (Instance->Media.LastBlock + 1)) {
+    DEBUG ((EFI_D_ERROR, "NorFlashRead: ERROR - Read will exceed last block\n"));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  if (Offset + BufferSizeInBytes >= Instance->Size) {
+    DEBUG ((EFI_D_ERROR, "NorFlashRead: ERROR - Read will exceed device size.\n"));
+    return EFI_INVALID_PARAMETER;
+  }
+
+  // Get the address to start reading from
+  StartAddress = GET_NOR_BLOCK_ADDRESS (Instance->RegionBaseAddress,
+                                        Lba,
+                                        Instance->Media.BlockSize
+                                       );
+
+  // Put the device into Read Array mode
+  SEND_NOR_COMMAND (Instance->DeviceBaseAddress, 0, P30_CMD_READ_ARRAY);
+
+  // Readout the data
+  CopyMem (Buffer, (UINTN *)(StartAddress + Offset), BufferSizeInBytes);
+
+  return EFI_SUCCESS;
+}
+
+
 EFI_STATUS
 NorFlashReset (
   IN  NOR_FLASH_INSTANCE *Instance

ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe.h

@@ -304,6 +304,13 @@ NorFlashWriteBlocks (
   IN  VOID              *Buffer
   );
 
+EFI_STATUS
+NorFlashWriteSingleWord (
+  IN NOR_FLASH_INSTANCE     *Instance,
+  IN UINTN                  WordAddress,
+  IN UINT32                 WriteData
+  );
+
 EFI_STATUS
 NorFlashReadBlocks (
   IN NOR_FLASH_INSTANCE   *Instance,
@@ -312,9 +319,24 @@ NorFlashReadBlocks (
   OUT VOID                *Buffer
   );
 
+EFI_STATUS
+NorFlashRead (
+  IN NOR_FLASH_INSTANCE   *Instance,
+  IN EFI_LBA              Lba,
+  IN UINTN                Offset,
+  IN UINTN                BufferSizeInBytes,
+  OUT VOID                *Buffer
+  );
+
 EFI_STATUS
 NorFlashReset (
   IN  NOR_FLASH_INSTANCE *Instance
   );
 
+EFI_STATUS
+NorFlashUnlockSingleBlockIfNecessary (
+  IN NOR_FLASH_INSTANCE     *Instance,
+  IN UINTN                  BlockAddress
+  );
+
 #endif /* __NOR_FLASH_DXE_H__ */

ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashFvbDxe.c

@@ -417,7 +417,6 @@ FvbRead (
   IN OUT    UINT8                                 *Buffer
   )
 {
-  EFI_STATUS    Status;
   EFI_STATUS    TempStatus;
   UINTN         BlockSize;
   NOR_FLASH_INSTANCE *Instance;
@@ -430,8 +429,7 @@ FvbRead (
     Instance->Initialize(Instance);
   }
 
-  Status = EFI_SUCCESS;
+  TempStatus = EFI_SUCCESS;
-  TempStatus = Status;
 
   // Cache the block size to avoid de-referencing pointers all the time
   BlockSize = Instance->Media.BlockSize;
@@ -452,25 +450,21 @@ FvbRead (
     return EFI_BAD_BUFFER_SIZE;
   }
 
-  // Check we did get some memory
+  // Decide if we are doing full block reads or not.
-  if (Instance->FvbBuffer == NULL) {
+  if (*NumBytes % BlockSize != 0) {
-    DEBUG ((EFI_D_ERROR, "FvbRead: ERROR - Buffer not ready\n"));
+    TempStatus = NorFlashRead (Instance, Instance->StartLba + Lba, Offset, *NumBytes, Buffer);
+    if (EFI_ERROR (TempStatus)) {
       return EFI_DEVICE_ERROR;
     }
-
+  } else {
     // Read NOR Flash data into shadow buffer
-  TempStatus = NorFlashReadBlocks (Instance, Instance->StartLba + Lba, BlockSize, Instance->FvbBuffer);
+    TempStatus = NorFlashReadBlocks (Instance, Instance->StartLba + Lba, BlockSize, Buffer);
     if (EFI_ERROR (TempStatus)) {
       // Return one of the pre-approved error statuses
       return EFI_DEVICE_ERROR;
     }
-
+  }
-  // Put the data at the appropriate location inside the buffer area
+  return EFI_SUCCESS;
-  DEBUG ((DEBUG_BLKIO, "FvbRead: CopyMem( Dst=0x%08x, Src=0x%08x, Size=0x%x ).\n", Buffer, (UINTN)Instance->FvbBuffer + Offset, *NumBytes));
-
-  CopyMem (Buffer, (VOID*)((UINTN)Instance->FvbBuffer + Offset), *NumBytes);
-
-  return Status;
 }
 
 /**
@@ -537,10 +531,21 @@ FvbWrite (
   IN        UINT8                                 *Buffer
   )
 {
-  EFI_STATUS  Status;
   EFI_STATUS  TempStatus;
+  UINT32      Tmp;
+  UINT32      TmpBuf;
+  UINT32      WordToWrite;
+  UINT32      Mask;
+  UINTN       DoErase;
+  UINTN       BytesToWrite;
+  UINTN       CurOffset;
+  UINTN       WordAddr;
   UINTN       BlockSize;
   NOR_FLASH_INSTANCE *Instance;
+  UINTN       BlockAddress;
+  UINTN       PrevBlockAddress;
+
+  PrevBlockAddress = 0;
 
   Instance = INSTANCE_FROM_FVB_THIS(This);
 
@@ -550,9 +555,6 @@ FvbWrite (
 
   DEBUG ((DEBUG_BLKIO, "FvbWrite(Parameters: Lba=%ld, Offset=0x%x, *NumBytes=0x%x, Buffer @ 0x%08x)\n", Instance->StartLba + Lba, Offset, *NumBytes, Buffer));
 
-  Status = EFI_SUCCESS;
-  TempStatus = Status;
-
   // Detect WriteDisabled state
   if (Instance->Media.ReadOnly == TRUE) {
     DEBUG ((EFI_D_ERROR, "FvbWrite: ERROR - Can not write: Device is in WriteDisabled state.\n"));
@@ -578,7 +580,129 @@ FvbWrite (
     return EFI_BAD_BUFFER_SIZE;
   }
 
-  // Check we did get some memory
+  // Pick 128bytes as a good start for word operations as opposed to erasing the
+  // block and writing the data regardless if an erase is really needed.
+  // It looks like most individual NV variable writes are smaller than 128bytes.
+  if (*NumBytes <= 128) {
+    // Check to see if we need to erase before programming the data into NOR.
+    // If the destination bits are only changing from 1s to 0s we can just write.
+    // After a block is erased all bits in the block is set to 1.
+    // If any byte requires us to erase we just give up and rewrite all of it.
+    DoErase = 0;
+    BytesToWrite = *NumBytes;
+    CurOffset = Offset;
+
+    while (BytesToWrite > 0) {
+      // Read full word from NOR, splice as required. A word is the smallest
+      // unit we can write.
+      TempStatus = NorFlashRead (Instance, Instance->StartLba + Lba,
+                                 CurOffset & ~(0x3), sizeof(Tmp), &Tmp);
+      if (EFI_ERROR (TempStatus)) {
+        return EFI_DEVICE_ERROR;
+      }
+
+      // Physical address of word in NOR to write.
+      WordAddr = (CurOffset & ~(0x3)) + GET_NOR_BLOCK_ADDRESS (Instance->RegionBaseAddress,
+                                                               Lba, BlockSize);
+      // The word of data that is to be written.
+      TmpBuf = *((UINT32*)(Buffer + (*NumBytes - BytesToWrite)));
+
+      // First do word aligned chunks.
+      if ((CurOffset & 0x3) == 0) {
+        if (BytesToWrite >= 4) {
+          // Is the destination still in 'erased' state?
+          if (~Tmp != 0) {
+            // Check to see if we are only changing bits to zero.
+            if ((Tmp ^ TmpBuf) & TmpBuf) {
+              DoErase = 1;
+              break;
+            }
+          }
+          // Write this word to NOR
+          WordToWrite = TmpBuf;
+          CurOffset += sizeof(TmpBuf);
+          BytesToWrite -= sizeof(TmpBuf);
+        } else {
+          // BytesToWrite < 4. Do small writes and left-overs
+          Mask = ~((~0) << (BytesToWrite * 8));
+          // Mask out the bytes we want.
+          TmpBuf &= Mask;
+          // Is the destination still in 'erased' state?
+          if ((Tmp & Mask) != Mask) {
+            // Check to see if we are only changing bits to zero.
+            if ((Tmp ^ TmpBuf) & TmpBuf) {
+              DoErase = 1;
+              break;
+            }
+          }
+          // Merge old and new data. Write merged word to NOR
+          WordToWrite = (Tmp & ~Mask) | TmpBuf;
+          CurOffset += BytesToWrite;
+          BytesToWrite = 0;
+        }
+      } else {
+        // Do multiple words, but starting unaligned.
+        if (BytesToWrite > (4 - (CurOffset & 0x3))) {
+          Mask = ~((~0) << ((CurOffset & 0x3) * 8));
+          // Mask out the bytes we want.
+          TmpBuf = (TmpBuf << ((CurOffset & 0x3) * 8)) & Mask;
+          // Is the destination still in 'erased' state?
+          if ((Tmp & Mask) != Mask) {
+            // Check to see if we are only changing bits to zero.
+            if ((Tmp ^ TmpBuf) & TmpBuf) {
+              DoErase = 1;
+              break;
+            }
+          }
+          // Merge old and new data. Write merged word to NOR
+          WordToWrite = (Tmp & ~Mask) | TmpBuf;
+          BytesToWrite -= (4 - (CurOffset & 0x3));
+          CurOffset += (4 - (CurOffset & 0x3));
+        } else {
+          // Unaligned and fits in one word.
+          Mask = (~((~0) << (BytesToWrite * 8))) << ((CurOffset & 0x3) * 8);
+          // Mask out the bytes we want.
+          TmpBuf = (TmpBuf << ((CurOffset & 0x3) * 8)) & Mask;
+          // Is the destination still in 'erased' state?
+          if ((Tmp & Mask) != Mask) {
+            // Check to see if we are only changing bits to zero.
+            if ((Tmp ^ TmpBuf) & TmpBuf) {
+              DoErase = 1;
+              break;
+            }
+          }
+          // Merge old and new data. Write merged word to NOR
+          WordToWrite = (Tmp & ~Mask) | TmpBuf;
+          CurOffset += BytesToWrite;
+          BytesToWrite = 0;
+        }
+      }
+
+      //
+      // Write the word to NOR.
+      //
+
+      BlockAddress = GET_NOR_BLOCK_ADDRESS (Instance->RegionBaseAddress, Lba, BlockSize);
+      if (BlockAddress != PrevBlockAddress) {
+        TempStatus = NorFlashUnlockSingleBlockIfNecessary (Instance, BlockAddress);
+        if (EFI_ERROR (TempStatus)) {
+          return EFI_DEVICE_ERROR;
+        }
+        PrevBlockAddress = BlockAddress;
+      }
+      TempStatus = NorFlashWriteSingleWord (Instance, WordAddr, WordToWrite);
+      if (EFI_ERROR (TempStatus)) {
+        return EFI_DEVICE_ERROR;
+      }
+    }
+    // Exit if we got here and could write all the data. Otherwise do the
+    // Erase-Write cycle.
+    if (!DoErase) {
+      return EFI_SUCCESS;
+    }
+  }
+
+  // Check we did get some memory. Buffer is BlockSize.
   if (Instance->FvbBuffer == NULL) {
     DEBUG ((EFI_D_ERROR, "FvbWrite: ERROR - Buffer not ready\n"));
     return EFI_DEVICE_ERROR;
@@ -601,7 +725,7 @@ FvbWrite (
     return EFI_DEVICE_ERROR;
   }
 
-  return Status;
+  return EFI_SUCCESS;
 }
 
 /**