/*
 * YAFFS: Yet another FFS. A NAND-flash specific file system. 
 * yaffs_tagscompat.h: Tags compatability layer to use YAFFS1 formatted NAND.
 *
 * Copyright (C) 2002 Aleph One Ltd.
 *
 * Created by Charles Manning <charles@aleph1.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * $Id: yaffs_tagscompat.c,v 1.2 2005/03/16 04:00:36 charles Exp $
 */

#include "yaffs_guts.h"
#include "yaffs_tagscompat.h"
#include "yaffs_ecc.h"

static void yaffs_HandleReadDataError(yaffs_Device *dev,int chunkInNAND);
static void yaffs_CheckWrittenBlock(yaffs_Device *dev,int chunkInNAND);
static void yaffs_HandleWriteChunkOk(yaffs_Device *dev,int chunkInNAND,const __u8 *data, const yaffs_Spare *spare);
static void yaffs_HandleUpdateChunk(yaffs_Device *dev,int chunkInNAND, const yaffs_Spare *spare);
static void yaffs_HandleWriteChunkError(yaffs_Device *dev,int chunkInNAND);



static const char yaffs_countBitsTable[256] =
{
0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,
1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8
};

static int yaffs_CountBits(__u8 x)
{
	int retVal;
	retVal = yaffs_countBitsTable[x];
	return retVal;
}


/////////////// Tags ECC calculations ///////////////////

void yaffs_CalcECC(const __u8 *data, yaffs_Spare *spare)
{
	yaffs_ECCCalculate(data , spare->ecc1);
	yaffs_ECCCalculate(&data[256] , spare->ecc2);
}

void yaffs_CalcTagsECC(yaffs_Tags *tags)
{
	// Calculate an ecc

	unsigned char *b = ((yaffs_TagsUnion *)tags)->asBytes;
	unsigned  i,j;
	unsigned  ecc = 0;
	unsigned bit = 0;

	tags->ecc = 0;

	for(i = 0; i < 8; i++)
	{
		for(j = 1; j &0xff; j<<=1)
		{
			bit++;
			if(b[i] & j)
			{
				ecc ^= bit;
			}
		}
	}

	tags->ecc = ecc;


}

int  yaffs_CheckECCOnTags(yaffs_Tags *tags)
{
	unsigned ecc = tags->ecc;

	yaffs_CalcTagsECC(tags);

	ecc ^= tags->ecc;
	
	if(ecc && ecc <= 64)
	{
		// TODO: Handle the failure better. Retire?
		unsigned char *b = ((yaffs_TagsUnion *)tags)->asBytes;

		ecc--;

		b[ecc / 8] ^= (1 << (ecc & 7));

		// Now recvalc the ecc
		yaffs_CalcTagsECC(tags);

		return 1; // recovered error
	}
	else if(ecc)
	{
		// Wierd ecc failure value
		// TODO Need to do somethiong here
		return -1; //unrecovered error
	}

	return 0;
}

//////////////////////////// Tags ///////////////////////////////////////

static void yaffs_LoadTagsIntoSpare(yaffs_Spare *sparePtr, yaffs_Tags *tagsPtr)
{
	yaffs_TagsUnion *tu = (yaffs_TagsUnion *)tagsPtr;

	yaffs_CalcTagsECC(tagsPtr);
	
	sparePtr->tagByte0 = tu->asBytes[0];
	sparePtr->tagByte1 = tu->asBytes[1];
	sparePtr->tagByte2 = tu->asBytes[2];
	sparePtr->tagByte3 = tu->asBytes[3];
	sparePtr->tagByte4 = tu->asBytes[4];
	sparePtr->tagByte5 = tu->asBytes[5];
	sparePtr->tagByte6 = tu->asBytes[6];
	sparePtr->tagByte7 = tu->asBytes[7];
}

static void yaffs_GetTagsFromSpare(yaffs_Device *dev, yaffs_Spare *sparePtr,yaffs_Tags *tagsPtr)
{
	yaffs_TagsUnion *tu = (yaffs_TagsUnion *)tagsPtr;
	int result;

	tu->asBytes[0]= sparePtr->tagByte0;
	tu->asBytes[1]= sparePtr->tagByte1;
	tu->asBytes[2]= sparePtr->tagByte2;
	tu->asBytes[3]= sparePtr->tagByte3;
	tu->asBytes[4]= sparePtr->tagByte4;
	tu->asBytes[5]= sparePtr->tagByte5;
	tu->asBytes[6]= sparePtr->tagByte6;
	tu->asBytes[7]= sparePtr->tagByte7;
	
	result =  yaffs_CheckECCOnTags(tagsPtr);
	if(result> 0)
	{
		dev->tagsEccFixed++;
	}
	else if(result <0)
	{
		dev->tagsEccUnfixed++;
	}
}

static void yaffs_SpareInitialise(yaffs_Spare *spare)
{
	memset(spare,0xFF,sizeof(yaffs_Spare));
}




static int yaffs_WriteChunkToNAND(struct yaffs_DeviceStruct *dev,int chunkInNAND, const __u8 *data, yaffs_Spare *spare)
{
	if(chunkInNAND < dev->startBlock * dev->nChunksPerBlock)
	{
		T(YAFFS_TRACE_ERROR,(TSTR("**>> yaffs chunk %d is not valid\n"),chunkInNAND));
		return YAFFS_FAIL;
	}

	dev->nPageWrites++;
	return dev->writeChunkToNAND(dev,chunkInNAND,data,spare);
}

static int yaffs_ReadChunkFromNAND(struct yaffs_DeviceStruct *dev,
							int chunkInNAND, 
							__u8 *data, 
							yaffs_Spare *spare,
							yaffs_ECCResult *eccResult,
							int doErrorCorrection)
{
	int retVal;
	yaffs_Spare localSpare;

	dev->nPageReads++;

	
	if(!spare && data) {
		// If we don't have a real spare, then we use a local one.
		// Need this for the calculation of the ecc
		spare = &localSpare;
	}
	

	if (!dev->useNANDECC) {
		retVal  = dev->readChunkFromNAND(dev,chunkInNAND,data,spare);
		if (data && doErrorCorrection) {
			// Do ECC correction
			//Todo handle any errors
         	int eccResult1,eccResult2;
        	__u8 calcEcc[3];
                
			yaffs_ECCCalculate(data,calcEcc);
			eccResult1 = yaffs_ECCCorrect (data,spare->ecc1, calcEcc);
			yaffs_ECCCalculate(&data[256],calcEcc);
			eccResult2 = yaffs_ECCCorrect(&data[256],spare->ecc2, calcEcc);

			if(eccResult1>0) {
				T(YAFFS_TRACE_ERROR, (TSTR("**>>ecc error fix performed on chunk %d:0\n"),chunkInNAND));
				dev->eccFixed++;
			}
			else if(eccResult1<0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error unfixed on chunk %d:0\n"),chunkInNAND));
				dev->eccUnfixed++;
			}

			if(eccResult2>0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error fix performed on chunk %d:1\n"),chunkInNAND));
				dev->eccFixed++;
			} else if(eccResult2<0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error unfixed on chunk %d:1\n"),chunkInNAND));
				dev->eccUnfixed++;
			}

			if(eccResult1 || eccResult2) {
				// Hoosterman, we had a data problem on this page
				yaffs_HandleReadDataError(dev,chunkInNAND);
			}
			
			if(eccResult1 < 0 || eccResult2 < 0) 
				*eccResult = YAFFS_ECC_RESULT_UNFIXED;
			else if(eccResult1 > 0 || eccResult2 > 0)
				*eccResult = YAFFS_ECC_RESULT_FIXED;
			else
				*eccResult = YAFFS_ECC_RESULT_NO_ERROR;
		}
	} else {
        // Must allocate enough memory for spare+2*sizeof(int) for ecc results from device.
    	struct yaffs_NANDSpare nspare;
		retVal  = dev->readChunkFromNAND(dev,chunkInNAND,data,(yaffs_Spare*)&nspare);
		memcpy (spare, &nspare, sizeof(yaffs_Spare));
		if(data && doErrorCorrection) {
			if(nspare.eccres1>0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error fix performed on chunk %d:0\n"),chunkInNAND));
			}
			else if(nspare.eccres1<0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error unfixed on chunk %d:0\n"),chunkInNAND));
			}

			if(nspare.eccres2>0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error fix performed on chunk %d:1\n"),chunkInNAND));
			}
			else if(nspare.eccres2<0) {
				T(YAFFS_TRACE_ERROR,(TSTR("**>>ecc error unfixed on chunk %d:1\n"),chunkInNAND));
			}

			if(nspare.eccres1 || nspare.eccres2) {
				// Hoosterman, we had a data problem on this page
				yaffs_HandleReadDataError(dev,chunkInNAND);
			}
			
			if(nspare.eccres1 < 0 || nspare.eccres2 < 0) 
				*eccResult = YAFFS_ECC_RESULT_UNFIXED;
			else if(nspare.eccres1 > 0 || nspare.eccres2 > 0)
				*eccResult = YAFFS_ECC_RESULT_FIXED;
			else
				*eccResult = YAFFS_ECC_RESULT_NO_ERROR;
		}
	}
	return retVal;
}

static int yaffs_CheckChunkErased(struct yaffs_DeviceStruct *dev,int chunkInNAND)
{
	static int init = 0;
	static __u8 cmpbuf[YAFFS_BYTES_PER_CHUNK];
	static __u8 data[YAFFS_BYTES_PER_CHUNK];
	// Might as well always allocate the larger size for dev->useNANDECC == true;
	static __u8 spare[sizeof(struct yaffs_NANDSpare)];

  	dev->readChunkFromNAND(dev,chunkInNAND,data,(yaffs_Spare *)spare);

	if (!init) {
		memset(cmpbuf,0xff,YAFFS_BYTES_PER_CHUNK);
		init = 1;
	}

	if (memcmp(cmpbuf, data, YAFFS_BYTES_PER_CHUNK))
		return  YAFFS_FAIL;

	if (memcmp(cmpbuf, spare, 16))
		return YAFFS_FAIL;

	return YAFFS_OK;
}


#if 0
int yaffs_EraseBlockInNAND(struct yaffs_DeviceStruct *dev,int blockInNAND)
{
	dev->nBlockErasures++;
	return dev->eraseBlockInNAND(dev,blockInNAND);
}

int yaffs_InitialiseNAND(struct yaffs_DeviceStruct *dev)
{
	return dev->initialiseNAND(dev);
}

#endif

#if 0
static int yaffs_WriteNewChunkToNAND(struct yaffs_DeviceStruct *dev, const __u8 *data, yaffs_Spare *spare,int useReserve)
{
	int chunk;

	int writeOk = 1;
	int attempts = 0;

	unsigned char rbData[YAFFS_BYTES_PER_CHUNK];
	yaffs_Spare rbSpare;

	do{
		chunk = yaffs_AllocateChunk(dev,useReserve);

		if(chunk >= 0)
		{

			// First check this chunk is erased...
#ifndef CONFIG_YAFFS_DISABLE_CHUNK_ERASED_CHECK
			writeOk = yaffs_CheckChunkErased(dev,chunk);
#endif
			if(!writeOk)
			{
				T(YAFFS_TRACE_ERROR,(TSTR("**>> yaffs chunk %d was not erased\n"),chunk));
			}
			else
			{
				writeOk =  yaffs_WriteChunkToNAND(dev,chunk,data,spare);
			}
			attempts++;
			if(writeOk)
			{
				// Readback & verify
				// If verify fails, then delete this chunk and try again
				// To verify we compare everything except the block and
				// page status bytes.
				// NB We check a raw read without ECC correction applied
				yaffs_ReadChunkFromNAND(dev,chunk,rbData,&rbSpare,0);

#ifndef CONFIG_YAFFS_DISABLE_WRITE_VERIFY
				if(!yaffs_VerifyCompare(data,rbData,spare,&rbSpare))
				{
					// Didn't verify
					T(YAFFS_TRACE_ERROR,(TSTR("**>> yaffs write verify failed on chunk %d\n"), chunk));

					writeOk = 0;
				}
#endif

			}
			if(writeOk)
			{
				// Copy the data into the write buffer.
				// NB We do this at the end to prevent duplicates in the case of a write error.
				//Todo
				yaffs_HandleWriteChunkOk(dev,chunk,data,spare);
			}
			else
			{
				yaffs_HandleWriteChunkError(dev,chunk);
			}
		}

	} while(chunk >= 0 && ! writeOk);

	if(attempts > 1)
	{
		T(YAFFS_TRACE_ERROR,(TSTR("**>> yaffs write required %d attempts\n"),attempts));
		dev->nRetriedWrites+= (attempts - 1);
	}

	return chunk;
}

#endif

///
// Functions for robustisizing
//
//
#if 0

static void yaffs_RetireBlock(yaffs_Device *dev,int blockInNAND)
{
	// Ding the blockStatus in the first two pages of the block.

	yaffs_Spare spare;

	memset(&spare, 0xff,sizeof(yaffs_Spare));

	spare.blockStatus = 0;

	// TODO change this retirement marking for other NAND types
	yaffs_WriteChunkToNAND(dev, blockInNAND * dev->nChunksPerBlock, NULL , &spare);
	yaffs_WriteChunkToNAND(dev, blockInNAND * dev->nChunksPerBlock + 1, NULL , &spare);

	yaffs_GetBlockInfo(dev,blockInNAND)->blockState = YAFFS_BLOCK_STATE_DEAD;
	dev->nRetiredBlocks++;
}

#endif

#if 0
static int yaffs_RewriteBufferedBlock(yaffs_Device *dev)
{
	dev->doingBufferedBlockRewrite = 1;
	//
	//	Remove erased chunks
	//  Rewrite existing chunks to a new block
	//	Set current write block to the new block

	dev->doingBufferedBlockRewrite = 0;

	return 1;
}

#endif

static void yaffs_HandleReadDataError(yaffs_Device *dev,int chunkInNAND)
{
	int blockInNAND = chunkInNAND/dev->nChunksPerBlock;

	// Mark the block for retirement
	yaffs_GetBlockInfo(dev,blockInNAND)->needsRetiring = 1;
	T(YAFFS_TRACE_ERROR | YAFFS_TRACE_BAD_BLOCKS,(TSTR("**>>Block %d marked for retirement\n"),blockInNAND));


	//TODO
	// Just do a garbage collection on the affected block then retire the block
	// NB recursion
}


static void yaffs_CheckWrittenBlock(yaffs_Device *dev,int chunkInNAND)
{
}

static void yaffs_HandleWriteChunkOk(yaffs_Device *dev,int chunkInNAND,const __u8 *data, const yaffs_Spare *spare)
{
}

static void yaffs_HandleUpdateChunk(yaffs_Device *dev,int chunkInNAND, const yaffs_Spare *spare)
{
}

static void yaffs_HandleWriteChunkError(yaffs_Device *dev,int chunkInNAND)
{
	int blockInNAND = chunkInNAND/dev->nChunksPerBlock;

	// Mark the block for retirement
	yaffs_GetBlockInfo(dev,blockInNAND)->needsRetiring = 1;
	// Delete the chunk
	yaffs_DeleteChunk(dev,chunkInNAND,1,__LINE__);
}

static int yaffs_VerifyCompare(const __u8 *d0, const __u8 * d1,
		const yaffs_Spare *s0, const yaffs_Spare *s1)
{
	if (memcmp(d0,d1,YAFFS_BYTES_PER_CHUNK) != 0 ||
		s0->tagByte0 != s1->tagByte0 ||
		s0->tagByte1 != s1->tagByte1 ||
		s0->tagByte2 != s1->tagByte2 ||
		s0->tagByte3 != s1->tagByte3 ||
		s0->tagByte4 != s1->tagByte4 ||
		s0->tagByte5 != s1->tagByte5 ||
		s0->tagByte6 != s1->tagByte6 ||
		s0->tagByte7 != s1->tagByte7 ||
		s0->ecc1[0]  != s1->ecc1[0]  ||
		s0->ecc1[1]  != s1->ecc1[1]  ||
		s0->ecc1[2]  != s1->ecc1[2]  ||
		s0->ecc2[0]  != s1->ecc2[0]  ||
		s0->ecc2[1]  != s1->ecc2[1]  ||
		s0->ecc2[2]  != s1->ecc2[2] ) {
			return 0;
		}

	return 1;
}

#if 0
typedef struct
{

	unsigned validMarker0;
	unsigned chunkUsed;		    //  Status of the chunk: used or unused
	unsigned objectId;			// If 0 then this is not part of an object (unused)
	unsigned chunkId;			// If 0 then this is a header
	unsigned byteCount;		    // Only valid for data chunks
	// The following stuff only has meaning when we read
	yaffs_ECCResult eccResult;  // Only valid when we read.
	unsigned blockBad;			// Only valid on reading

	// YAFFS 1 stuff	
	unsigned chunkDeleted;		// The chunk is marked deleted
	unsigned serialNumber; 		// Yaffs1 2-bit serial number
	
	// YAFFS2 stuff
	unsigned sequenceNumber; 	// The sequence number of this block

	unsigned validMarker1;

} yaffs_ExtendedTags;


typedef struct
{   
    unsigned chunkId:20;
    unsigned serialNumber:2;
    unsigned byteCount:10;
    unsigned objectId:18;
    unsigned ecc:12;
    unsigned unusedStuff:2;
} yaffs_Tags;


#endif

int yaffs_TagsCompatabilityWriteChunkWithTagsToNAND(yaffs_Device *dev,int chunkInNAND,const __u8 *data, const yaffs_ExtendedTags *eTags)
{
	yaffs_Spare spare;
	yaffs_Tags tags;	
	
	yaffs_SpareInitialise(&spare);
	
	if(eTags->chunkDeleted)
	{
		spare.pageStatus = 0;
	}
	else
	{
		tags.objectId = eTags->objectId;
		tags.chunkId = eTags->chunkId;
		tags.byteCount = eTags->byteCount;
		tags.serialNumber = eTags->serialNumber;
		
// NCB
		if (!dev->useNANDECC && data)
		{
		    yaffs_CalcECC(data,&spare);
		}

// /NCB
		 yaffs_LoadTagsIntoSpare(&spare,&tags);
		
	}
	
	return yaffs_WriteChunkToNAND(dev,chunkInNAND,data,&spare);
}

int yaffs_TagsCompatabilityReadChunkWithTagsFromNAND(yaffs_Device *dev, int chunkInNAND,
		__u8 *data, yaffs_ExtendedTags *eTags)
{
	yaffs_Spare spare;
	yaffs_Tags tags;
	yaffs_ECCResult eccResult;

// NCB
     static yaffs_Spare spareFF;
     static int init;
     
	if (!init) {
	     memset(&spareFF,0xFF,sizeof(spareFF));
	     init = 1;
	}
// /NCB
	if (yaffs_ReadChunkFromNAND(dev,chunkInNAND,data,&spare,&eccResult,1)) {
// added NCB - eTags may be NULL
		if (eTags) {

		 int deleted = (yaffs_CountBits(spare.pageStatus) < 7) ? 1 : 0;
			
		 yaffs_GetTagsFromSpare(dev,&spare,&tags);
		 
		 eTags->chunkDeleted = deleted;
		 eTags->objectId = tags.objectId;
		 eTags->chunkId = tags.chunkId;
		 eTags->byteCount = tags.byteCount;
		 eTags->serialNumber = tags.serialNumber;
		 eTags->eccResult = eccResult;
		 eTags->blockBad = 0; // We're reading it therefore it is not a bad block
		 
// NCB added 18/2/2005
    		 eTags->chunkUsed = (memcmp(&spareFF,&spare,sizeof(spareFF)) != 0) ? 1:0;
		}
		 
		 return YAFFS_OK;
	} else { 
		return YAFFS_FAIL;
	}
}

int yaffs_TagsCompatabilityMarkNANDBlockBad(struct yaffs_DeviceStruct *dev, int blockInNAND)
{
	yaffs_Spare spare;

	memset(&spare, 0xff,sizeof(yaffs_Spare));
	spare.blockStatus = 0;
	yaffs_WriteChunkToNAND(dev, blockInNAND * dev->nChunksPerBlock, NULL , &spare);
	yaffs_WriteChunkToNAND(dev, blockInNAND * dev->nChunksPerBlock + 1, NULL , &spare);

	return YAFFS_OK;
}

int yaffs_TagsCompatabilityQueryNANDBlock(struct yaffs_DeviceStruct *dev, int blockNo,
		yaffs_BlockState *state, int *sequenceNumber)
{
	static int init;
	static yaffs_Spare spareFF;
	yaffs_Spare spare0,spare1;
	yaffs_ECCResult dummy;
     
	if (!init) {
		memset(&spareFF,0xFF,sizeof(spareFF));
		init = 1;
	}
     
	*sequenceNumber = 0;
     
	yaffs_ReadChunkFromNAND(dev, blockNo * dev->nChunksPerBlock, NULL, &spare0,&dummy, 1);
	yaffs_ReadChunkFromNAND(dev, blockNo * dev->nChunksPerBlock + 1, NULL, &spare1, &dummy, 1);
     
	if (yaffs_CountBits(spare0.blockStatus & spare1.blockStatus) < 7)
     		*state = YAFFS_BLOCK_STATE_DEAD;
	else if (memcmp(&spareFF,&spare0,sizeof(spareFF)) == 0)
		*state = YAFFS_BLOCK_STATE_EMPTY;
	else
		*state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;  

	return YAFFS_OK;
} 
