/*
 * YAFFS: Yet another FFS. A NAND-flash specific file system. 
 * yaffs_ramem.c  NAND emulation on top of a chunk of RAM
 *
 * Copyright (C) 2002 Aleph One Ltd.
 *   for Toby Churchill Ltd and Brightstar Engineering
 *
 * 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.
 *
 */

 /* yaffs_ramem2k.c: RAM emulation in-kernel for 2K pages (YAFFS2) */

const char *yaffs_ramem2k_c_version = "$Id: yaffs_ramem2k.c,v 1.2 2005/04/24 09:26:08 charles Exp $";

#include <linux/config.h>

#ifndef __KERNEL__
#define CONFIG_YAFFS_RAM_ENABLED
#endif

#ifdef CONFIG_YAFFS_RAM_ENABLED

#include "yportenv.h"
#include "yaffs_nandemul2k.h"
#include "yaffs_guts.h"
#include "yaffsinterface.h"
#include "yaffs_packedtags2.h"

#define EM_SIZE_IN_MEG 32
#define PAGE_DATA_SIZE 2048
#define PAGE_SPARE_SIZE 64
#define PAGES_PER_BLOCK 64

#define EM_SIZE_IN_BYTES (EM_SIZE_IN_MEG * (1<<20))
#define PAGE_TOTAL_SIZE (PAGE_DATA_SIZE + PAGE_SPARE_SIZE)
#define BLOCK_TOTAL_SIZE (PAGES_PER_BLOCK * PAGE_TOTAL_SIZE)
#define BLOCKS_PER_MEG ((1<<20) / (PAGES_PER_BLOCK * PAGE_DATA_SIZE))

typedef struct {
	__u8 data[PAGE_TOTAL_SIZE];	// Data + spare
	int empty;			// is this empty?
} nandemul_Page;

typedef struct {
	nandemul_Page *page[PAGES_PER_BLOCK];
	int damaged;	
} nandemul_Block;

typedef struct {
	nandemul_Block **block;
	int nBlocks;
} nandemul_Device;

static nandemul_Device ned;
static int sizeInMB = EM_SIZE_IN_MEG;


static void nandemul_yield(int n)
{
#ifdef __KERNEL__
	if (n > 0)
		schedule_timeout(n);
#endif
}

static void nandemul_ReallyEraseBlock(int blockNumber)
{
	int i;
	nandemul_Block *blk;
	
	if (blockNumber < 0 || blockNumber >= ned.nBlocks)
		return;
	
	blk = ned.block[blockNumber];
	
	for(i = 0; i < PAGES_PER_BLOCK; i++) {
		memset(blk->page[i],0xff,sizeof(nandemul_Page));
		blk->page[i]->empty = 1;
	}
	nandemul_yield(2);
}

static int nandemul2k_CalcNBlocks(void)
{
	return EM_SIZE_IN_MEG * BLOCKS_PER_MEG;
}

static int CheckInit(void)
{
	static int initialised = 0;
	int i,j;
	int fail = 0;
	int nBlocks; 
	int nAllocated = 0;
	
	if (initialised) 
		return YAFFS_OK;
	
	ned.nBlocks = nBlocks = nandemul2k_CalcNBlocks();
	ned.block = kmalloc(sizeof(nandemul_Block*) * nBlocks, GFP_KERNEL);
	
	if (!ned.block)
		return YAFFS_FAIL;

	for (i = fail = 0; i < nBlocks; i++) {
		nandemul_Block *blk;
		
		blk = ned.block[i] = kmalloc(sizeof(nandemul_Block), GFP_KERNEL);
		if (!blk)
			fail = 1;
		else {
			for (j = 0; j < PAGES_PER_BLOCK; j++) {
				blk->page[j] = kmalloc(sizeof(nandemul_Page), GFP_KERNEL);
				if (blk->page[j] == 0)
					fail = 1;
			}
			nandemul_ReallyEraseBlock(i);
			ned.block[i]->damaged = 0;
			nAllocated++;
		}
	}
	
	if (fail) {
		//Todo thump pages
		
		for (i = 0; i < nAllocated; i++)
			kfree(ned. block[i]);

		kfree(ned.block);
		
		T(YAFFS_TRACE_ALWAYS, ("Allocation failed, could only allocate %dMB of %dMB requested.\n",
					nAllocated / 64, sizeInMB));
		return 0;
	}
	
	ned.nBlocks = nBlocks;
	initialised = 1;
	
	return 1;
}

int nandemul2k_WriteChunkWithTagsToNAND(yaffs_Device *dev,int chunkInNAND,const __u8 *data, yaffs_ExtendedTags *tags)
{
	int blk, pg;
	int i;
	
	__u8 *x;

	blk = chunkInNAND/PAGES_PER_BLOCK;
	pg = chunkInNAND%PAGES_PER_BLOCK;
	
	if(data) {
		x = ned.block[blk]->page[pg]->data;
		
		for(i = 0; i < PAGE_DATA_SIZE; i++)
			x[i] &=data[i];

		ned.block[blk]->page[pg]->empty = 0;
	}
	
	if(tags) {
		x = &ned.block[blk]->page[pg]->data[PAGE_DATA_SIZE];
		yaffs_PackTags2((yaffs_PackedTags2 *)x,tags);
	}
	
	if(tags || data)
		nandemul_yield(1);

	return YAFFS_OK;
}

int nandemul2k_ReadChunkWithTagsFromNAND(yaffs_Device *dev,int chunkInNAND, __u8 *data, yaffs_ExtendedTags *tags)
{
	int blk;
	int pg;
	
	__u8 *x;
	
	blk = chunkInNAND/PAGES_PER_BLOCK;
	pg = chunkInNAND%PAGES_PER_BLOCK;

	if(data)
		memcpy(data,ned.block[blk]->page[pg]->data,PAGE_DATA_SIZE);
	
	if(tags) {
		x = &ned.block[blk]->page[pg]->data[PAGE_DATA_SIZE];
		yaffs_UnpackTags2(tags,(yaffs_PackedTags2 *)x);
	}

	return YAFFS_OK;
}

int nandemul2k_CheckChunkErased(yaffs_Device *dev,int chunkInNAND)
{
	int blk, pg;
	int i;
	
	blk = chunkInNAND/PAGES_PER_BLOCK;
	pg = chunkInNAND%PAGES_PER_BLOCK;
	
	for(i = 0; i < PAGE_TOTAL_SIZE; i++) {
		if(ned.block[blk]->page[pg]->data[i] != 0xFF)
			return YAFFS_FAIL;
	}

	return YAFFS_OK;
}

int nandemul2k_EraseBlockInNAND(yaffs_Device *dev, int blockNumber)
{
	if(blockNumber < 0 || blockNumber >= ned.nBlocks)
		T(YAFFS_TRACE_ALWAYS,("Attempt to erase non-existant block %d\n",blockNumber));
	else if(ned.block[blockNumber]->damaged)
		T(YAFFS_TRACE_ALWAYS,("Attempt to erase damaged block %d\n",blockNumber));
	else
		nandemul_ReallyEraseBlock(blockNumber);
	
	return YAFFS_OK;
}

int nandemul2k_InitialiseNAND(yaffs_Device *dev)
{
	CheckInit();
	return YAFFS_OK;
}
 
int nandemul2k_MarkNANDBlockBad(struct yaffs_DeviceStruct *dev, int blockNo)
{
	__u8 *x;
	
	x = &ned.block[blockNo]->page[0]->data[PAGE_DATA_SIZE];
	memset(x,0,sizeof(yaffs_PackedTags2));
	
	return YAFFS_OK;
}

int nandemul2k_QueryNANDBlock(struct yaffs_DeviceStruct *dev, int blockNo, yaffs_BlockState *state, int *sequenceNumber)
{
	yaffs_ExtendedTags tags;
	int chunkNo;

	*sequenceNumber = 0;
	
	chunkNo = blockNo * dev->nChunksPerBlock;
	
	nandemul2k_ReadChunkWithTagsFromNAND(dev,chunkNo,NULL,&tags);
	if(tags.blockBad)
		*state = YAFFS_BLOCK_STATE_DEAD;
	else if(!tags.chunkUsed)
		*state = YAFFS_BLOCK_STATE_EMPTY;
	else if(tags.chunkUsed) {
		*state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
		*sequenceNumber = tags.sequenceNumber;
	}
	return YAFFS_OK;
}

int nandemul2k_GetBytesPerChunk(void) { return PAGE_DATA_SIZE;}

int nandemul2k_GetChunksPerBlock(void) { return PAGES_PER_BLOCK; }
int nandemul2k_GetNumberOfBlocks(void) {return nandemul2k_CalcNBlocks();}

#endif
