yaffs_ramdisk.c

flash 中实现yaffs的c 文件源码

/*
 * YAFFS: Yet another FFS. A NAND-flash specific file system. 
 * yaffs_ramdisk.c: yaffs ram disk component
 *
 * Copyright (C) 2002 Aleph One Ltd.
 *
 * Created by Charles Manning <[e-mail]>
 *
 * 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.
 *
 */

// This provides a ram disk under yaffs.
// NB this is not intended for NAND emulation.
// Use this with dev->useNANDECC enabled, then ECC overheads are not required.

#include "yportenv.h"
#include "devextras.h"
#include "yaffs_guts.h"
#include "yaffs_ramdisk.h"

#ifdef CONFIG_YAFFS_NOR_FLASH

int yramdisk_WriteChunkToNAND(yaffs_Device *dev, long chunkInNAND, const __u8 *data, yaffs_Spare *spare)
{
	return YAFFS_FAIL;
}

int yramdisk_ReadChunkFromNAND(yaffs_Device *dev, long chunkInNAND, __u8 *data, yaffs_Spare *spare)
{
	return YAFFS_FAIL;
}

int yramdisk_EraseBlockInNAND(yaffs_Device *dev, long blockNumber)
{
	return YAFFS_FAIL;
}

int yramdisk_InitialiseNAND(yaffs_Device *dev)
{
	return YAFFS_FAIL;
}

#else

typedef struct {
	__u8 data[YAFFS_BYTES_PER_CHUNK];
	__u8 spare[YAFFS_BYTES_PER_SPARE];
} yramdisk_Page;

typedef struct {
	yramdisk_Page page[YAFFS_CHUNKS_PER_BLOCK];
} yramdisk_Block;

static yramdisk_Block *yramdisk_mem_pool = NULL;
static long yramdisk_max_blks = 0;

int yramdisk_WriteChunkToNAND(yaffs_Device *dev, long chunkInNAND, const __u8 *data, yaffs_Spare *spare)
{
	long block = (chunkInNAND / YAFFS_CHUNKS_PER_BLOCK) - dev->startBlock;
	long page = chunkInNAND % YAFFS_CHUNKS_PER_BLOCK;

	if (yramdisk_mem_pool == NULL) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: No memory pool allocated for device\n")));
		return YAFFS_FAIL;
	}

	if ((block < 0) || (block >= yramdisk_max_blks)) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: Illegal chunk number %ld to write\n"), chunkInNAND));
		return YAFFS_FAIL;
	}

	if (data != NULL) {
		memcpy(yramdisk_mem_pool[block].page[page].data, data, YAFFS_BYTES_PER_CHUNK);
	}

	if (spare != NULL) {
		memcpy(yramdisk_mem_pool[block].page[page].spare, spare, YAFFS_BYTES_PER_SPARE);
	}

	return YAFFS_OK;
}

int yramdisk_ReadChunkFromNAND(yaffs_Device *dev, long chunkInNAND, __u8 *data, yaffs_Spare *spare)
{
	long block = (chunkInNAND / YAFFS_CHUNKS_PER_BLOCK) - dev->startBlock;
	long page = chunkInNAND % YAFFS_CHUNKS_PER_BLOCK;

	if (yramdisk_mem_pool == NULL) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: No memory pool allocated for device\n")));
		return YAFFS_FAIL;
	}

	if ((block < 0) || (block >= yramdisk_max_blks)) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: Illegal chunk number %ld to read\n"), chunkInNAND));
		return YAFFS_FAIL;
	}

	if (data != NULL) {
		memcpy(data, yramdisk_mem_pool[block].page[page].data, YAFFS_BYTES_PER_CHUNK);
	}

	if (spare != NULL) {
		memcpy(spare, yramdisk_mem_pool[block].page[page].spare, YAFFS_BYTES_PER_SPARE);

		if (dev->useNANDECC) {
			struct yaffs_NANDSpare *nsp = (struct yaffs_NANDSpare *)spare;

			nsp->eccres1 = 0;
			nsp->eccres2 = 0;
		}
	}

	return YAFFS_OK;
}

int yramdisk_EraseBlockInNAND(yaffs_Device *dev, long blockNumber)
{
	long block = blockNumber - dev->startBlock;

	if (yramdisk_mem_pool == NULL) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: No memory pool allocated for device\n")));
		return YAFFS_FAIL;
	}

	if ((block < 0) || (block >= yramdisk_max_blks)) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: Illegal block number %ld to erase\n"), blockNumber));
		return YAFFS_FAIL;
	}

	memset(&yramdisk_mem_pool[block], 0xFF, sizeof(yramdisk_Block));
	return YAFFS_OK;
}

int yramdisk_InitialiseNAND(yaffs_Device *dev)
{
	long block;

	yramdisk_max_blks = dev->endBlock - dev->startBlock + 1;
	yramdisk_mem_pool = Malloc(yramdisk_max_blks * sizeof(yramdisk_Block));

	if (yramdisk_mem_pool == NULL) {
		T(YAFFS_TRACE_ERROR, (TSTR("**>> ram: Allocate memory for device failed\n")));
		return YAFFS_FAIL;
	}

	for (block = 0; block < yramdisk_max_blks; block++) {
		memset(&yramdisk_mem_pool[block], 0xFF, sizeof(yramdisk_Block));
	}

#if 1
	dev->useNANDECC = 1; // force on useNANDECC which gets faked, this saves us doing ECC checks.
#endif

	return YAFFS_OK;
}

#endif /* CONFIG_YAFFS_NOR_FLASH */