- 根目录:
- fs
- yaffs2
- yaffs_mtdif1.c
/*
* YAFFS: Yet another FFS. A NAND-flash specific file system.
*
* Copyright (C) 2002-2010 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.
*/
/*
* This module provides the interface between yaffs_nand.c and the
* MTD API. This version is used when the MTD interface supports the
* 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
* and we have small-page NAND device.
*
* These functions are invoked via function pointers in yaffs_nand.c.
* This replaces functionality provided by functions in yaffs_mtdif.c
* and the yaffs_tags compatability functions in yaffs_tagscompat.c that are
* called in yaffs_mtdif.c when the function pointers are NULL.
* We assume the MTD layer is performing ECC (use_nand_ecc is true).
*/
#include "yportenv.h"
#include "yaffs_trace.h"
#include "yaffs_guts.h"
#include "yaffs_packedtags1.h"
#include "yaffs_tagscompat.h" /* for yaffs_calc_tags_ecc */
#include "yaffs_linux.h"
#include "linux/kernel.h"
#include "linux/version.h"
#include "linux/types.h"
#include "linux/mtd/mtd.h"
#ifndef CONFIG_YAFFS_9BYTE_TAGS
# define YTAG1_SIZE 8
#else
# define YTAG1_SIZE 9
#endif
/* Write a chunk (page) of data to NAND.
*
* Caller always provides ExtendedTags data which are converted to a more
* compact (packed) form for storage in NAND. A mini-ECC runs over the
* contents of the tags meta-data; used to valid the tags when read.
*
* - Pack ExtendedTags to packed_tags1 form
* - Compute mini-ECC for packed_tags1
* - Write data and packed tags to NAND.
*
* Note: Due to the use of the packed_tags1 meta-data which does not include
* a full sequence number (as found in the larger packed_tags2 form) it is
* necessary for Yaffs to re-write a chunk/page (just once) to mark it as
* discarded and dirty. This is not ideal: newer NAND parts are supposed
* to be written just once. When Yaffs performs this operation, this
* function is called with a NULL data pointer -- calling MTD write_oob
* without data is valid usage (2.6.17).
*
* Any underlying MTD error results in YAFFS_FAIL.
* Returns YAFFS_OK or YAFFS_FAIL.
*/
int nandmtd1_write_chunk_tags(struct yaffs_dev *dev,
int nand_chunk, const u8 * data,
const struct yaffs_ext_tags *etags)
{
struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
int chunk_bytes = dev->data_bytes_per_chunk;
loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
struct mtd_oob_ops ops;
struct yaffs_packed_tags1 pt1;
int retval;
/* we assume that packed_tags1 and struct yaffs_tags are compatible */
compile_time_assertion(sizeof(struct yaffs_packed_tags1) == 12);
compile_time_assertion(sizeof(struct yaffs_tags) == 8);
yaffs_pack_tags1(&pt1, etags);
yaffs_calc_tags_ecc((struct yaffs_tags *)&pt1);
/* When deleting a chunk, the upper layer provides only skeletal
* etags, one with is_deleted set. However, we need to update the
* tags, not erase them completely. So we use the NAND write property
* that only zeroed-bits stick and set tag bytes to all-ones and
* zero just the (not) deleted bit.
*/
#ifndef CONFIG_YAFFS_9BYTE_TAGS
if (etags->is_deleted) {
memset(&pt1, 0xff, 8);
/* clear delete status bit to indicate deleted */
pt1.deleted = 0;
}
#else
((u8 *) & pt1)[8] = 0xff;
if (etags->is_deleted) {
memset(&pt1, 0xff, 8);
/* zero page_status byte to indicate deleted */
((u8 *) & pt1)[8] = 0;
}
#endif
memset(&ops, 0, sizeof(ops));
ops.mode = MTD_OOB_AUTO;
ops.len = (data) ? chunk_bytes : 0;
ops.ooblen = YTAG1_SIZE;
ops.datbuf = (u8 *) data;
ops.oobbuf = (u8 *) & pt1;
retval = mtd->write_oob(mtd, addr, &ops);
if (retval) {
yaffs_trace(YAFFS_TRACE_MTD,
"write_oob failed, chunk %d, mtd error %d",
nand_chunk, retval);
}
return retval ? YAFFS_FAIL : YAFFS_OK;
}
/* Return with empty ExtendedTags but add ecc_result.
*/
static int rettags(struct yaffs_ext_tags *etags, int ecc_result, int retval)
{
if (etags) {
memset(etags, 0, sizeof(*etags));
etags->ecc_result = ecc_result;
}
return retval;
}
/* Read a chunk (page) from NAND.
*
* Caller expects ExtendedTags data to be usable even on error; that is,
* all members except ecc_result and block_bad are zeroed.
*
* - Check ECC results for data (if applicable)
* - Check for blank/erased block (return empty ExtendedTags if blank)
* - Check the packed_tags1 mini-ECC (correct if necessary/possible)
* - Convert packed_tags1 to ExtendedTags
* - Update ecc_result and block_bad members to refect state.
*
* Returns YAFFS_OK or YAFFS_FAIL.
*/
int nandmtd1_read_chunk_tags(struct yaffs_dev *dev,
int nand_chunk, u8 * data,
struct yaffs_ext_tags *etags)
{
struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
int chunk_bytes = dev->data_bytes_per_chunk;
loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
int eccres = YAFFS_ECC_RESULT_NO_ERROR;
struct mtd_oob_ops ops;
struct yaffs_packed_tags1 pt1;
int retval;
int deleted;
memset(&ops, 0, sizeof(ops));
ops.mode = MTD_OOB_AUTO;
ops.len = (data) ? chunk_bytes : 0;
ops.ooblen = YTAG1_SIZE;
ops.datbuf = data;
ops.oobbuf = (u8 *) & pt1;
/* Read page and oob using MTD.
* Check status and determine ECC result.
*/
retval = mtd->read_oob(mtd, addr, &ops);
if (retval) {
yaffs_trace(YAFFS_TRACE_MTD,
"read_oob failed, chunk %d, mtd error %d",
nand_chunk, retval);
}
switch (retval) {
case 0:
/* no error */
break;
case -EUCLEAN:
/* MTD's ECC fixed the data */
eccres = YAFFS_ECC_RESULT_FIXED;
dev->n_ecc_fixed++;
break;
case -EBADMSG:
/* MTD's ECC could not fix the data */
dev->n_ecc_unfixed++;
/* fall into... */
default:
rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
etags->block_bad = (mtd->block_isbad) (mtd, addr);
return YAFFS_FAIL;
}
/* Check for a blank/erased chunk.
*/
if (yaffs_check_ff((u8 *) & pt1, 8)) {
/* when blank, upper layers want ecc_result to be <= NO_ERROR */
return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
}
#ifndef CONFIG_YAFFS_9BYTE_TAGS
/* Read deleted status (bit) then return it to it's non-deleted
* state before performing tags mini-ECC check. pt1.deleted is
* inverted.
*/
deleted = !pt1.deleted;
pt1.deleted = 1;
#else
deleted = (yaffs_count_bits(((u8 *) & pt1)[8]) < 7);
#endif
/* Check the packed tags mini-ECC and correct if necessary/possible.
*/
retval = yaffs_check_tags_ecc((struct yaffs_tags *)&pt1);
switch (retval) {
case 0:
/* no tags error, use MTD result */
break;
case 1:
/* recovered tags-ECC error */
dev->n_tags_ecc_fixed++;
if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
eccres = YAFFS_ECC_RESULT_FIXED;
break;
default:
/* unrecovered tags-ECC error */
dev->n_tags_ecc_unfixed++;
return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
}
/* Unpack the tags to extended form and set ECC result.
* [set should_be_ff just to keep yaffs_unpack_tags1 happy]
*/
pt1.should_be_ff = 0xFFFFFFFF;
yaffs_unpack_tags1(etags, &pt1);
etags->ecc_result = eccres;
/* Set deleted state */
etags->is_deleted = deleted;
return YAFFS_OK;
}
/* Mark a block bad.
*
* This is a persistant state.
* Use of this function should be rare.
*
* Returns YAFFS_OK or YAFFS_FAIL.
*/
int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no)
{
struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
int retval;
yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
"marking block %d bad", block_no);
retval = mtd->block_markbad(mtd, (loff_t) blocksize * block_no);
return (retval) ? YAFFS_FAIL : YAFFS_OK;
}
/* Check any MTD prerequists.
*
* Returns YAFFS_OK or YAFFS_FAIL.
*/
static int nandmtd1_test_prerequists(struct mtd_info *mtd)
{
/* 2.6.18 has mtd->ecclayout->oobavail */
/* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
int oobavail = mtd->ecclayout->oobavail;
if (oobavail < YTAG1_SIZE) {
yaffs_trace(YAFFS_TRACE_ERROR,
"mtd device has only %d bytes for tags, need %d",
oobavail, YTAG1_SIZE);
return YAFFS_FAIL;
}
return YAFFS_OK;
}
/* Query for the current state of a specific block.
*
* Examine the tags of the first chunk of the block and return the state:
* - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
* - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
* - YAFFS_BLOCK_STATE_EMPTY, the block is clean
*
* Always returns YAFFS_OK.
*/
int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
enum yaffs_block_state *state_ptr, u32 * seq_ptr)
{
struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
int chunk_num = block_no * dev->param.chunks_per_block;
loff_t addr = (loff_t) chunk_num * dev->data_bytes_per_chunk;
struct yaffs_ext_tags etags;
int state = YAFFS_BLOCK_STATE_DEAD;
int seqnum = 0;
int retval;
/* We don't yet have a good place to test for MTD config prerequists.
* Do it here as we are called during the initial scan.
*/
if (nandmtd1_test_prerequists(mtd) != YAFFS_OK)
return YAFFS_FAIL;
retval = nandmtd1_read_chunk_tags(dev, chunk_num, NULL, &etags);
etags.block_bad = (mtd->block_isbad) (mtd, addr);
if (etags.block_bad) {
yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
"block %d is marked bad", block_no);
state = YAFFS_BLOCK_STATE_DEAD;
} else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
/* bad tags, need to look more closely */
state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
} else if (etags.chunk_used) {
state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
seqnum = etags.seq_number;
} else {
state = YAFFS_BLOCK_STATE_EMPTY;
}
*state_ptr = state;
*seq_ptr = seqnum;
/* query always succeeds */
return YAFFS_OK;
}