2 * YAFFS: Yet another FFS. A NAND-flash specific file system.
4 * Copyright (C) 2002-2010 Aleph One Ltd.
5 * for Toby Churchill Ltd and Brightstar Engineering
7 * Created by Charles Manning <charles@aleph1.co.uk>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
15 * This module provides the interface between yaffs_nand.c and the
16 * MTD API. This version is used when the MTD interface supports the
17 * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
18 * and we have small-page NAND device.
20 * These functions are invoked via function pointers in yaffs_nand.c.
21 * This replaces functionality provided by functions in yaffs_mtdif.c
22 * and the yaffs_tags compatability functions in yaffs_tagscompat.c that are
23 * called in yaffs_mtdif.c when the function pointers are NULL.
24 * We assume the MTD layer is performing ECC (use_nand_ecc is true).
28 #include "yaffs_trace.h"
29 #include "yaffs_guts.h"
30 #include "yaffs_packedtags1.h"
31 #include "yaffs_tagscompat.h" /* for yaffs_calc_tags_ecc */
32 #include "yaffs_linux.h"
34 #include "linux/kernel.h"
35 #include "linux/version.h"
36 #include "linux/types.h"
37 #include "linux/mtd/mtd.h"
39 #ifndef CONFIG_YAFFS_9BYTE_TAGS
46 /* Write a chunk (page) of data to NAND.
48 * Caller always provides ExtendedTags data which are converted to a more
49 * compact (packed) form for storage in NAND. A mini-ECC runs over the
50 * contents of the tags meta-data; used to valid the tags when read.
52 * - Pack ExtendedTags to packed_tags1 form
53 * - Compute mini-ECC for packed_tags1
54 * - Write data and packed tags to NAND.
56 * Note: Due to the use of the packed_tags1 meta-data which does not include
57 * a full sequence number (as found in the larger packed_tags2 form) it is
58 * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
59 * discarded and dirty. This is not ideal: newer NAND parts are supposed
60 * to be written just once. When Yaffs performs this operation, this
61 * function is called with a NULL data pointer -- calling MTD write_oob
62 * without data is valid usage (2.6.17).
64 * Any underlying MTD error results in YAFFS_FAIL.
65 * Returns YAFFS_OK or YAFFS_FAIL.
67 int nandmtd1_write_chunk_tags(yaffs_dev_t *dev,
68 int nand_chunk, const __u8 *data, const yaffs_ext_tags *etags)
70 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
71 int chunk_bytes = dev->data_bytes_per_chunk;
72 loff_t addr = ((loff_t)nand_chunk) * chunk_bytes;
73 struct mtd_oob_ops ops;
74 yaffs_packed_tags1 pt1;
77 /* we assume that packed_tags1 and yaffs_tags_t are compatible */
78 compile_time_assertion(sizeof(yaffs_packed_tags1) == 12);
79 compile_time_assertion(sizeof(yaffs_tags_t) == 8);
81 yaffs_pack_tags1(&pt1, etags);
82 yaffs_calc_tags_ecc((yaffs_tags_t *)&pt1);
84 /* When deleting a chunk, the upper layer provides only skeletal
85 * etags, one with is_deleted set. However, we need to update the
86 * tags, not erase them completely. So we use the NAND write property
87 * that only zeroed-bits stick and set tag bytes to all-ones and
88 * zero just the (not) deleted bit.
90 #ifndef CONFIG_YAFFS_9BYTE_TAGS
91 if (etags->is_deleted) {
92 memset(&pt1, 0xff, 8);
93 /* clear delete status bit to indicate deleted */
97 ((__u8 *)&pt1)[8] = 0xff;
98 if (etags->is_deleted) {
99 memset(&pt1, 0xff, 8);
100 /* zero page_status byte to indicate deleted */
101 ((__u8 *)&pt1)[8] = 0;
105 memset(&ops, 0, sizeof(ops));
106 ops.mode = MTD_OOB_AUTO;
107 ops.len = (data) ? chunk_bytes : 0;
108 ops.ooblen = YTAG1_SIZE;
109 ops.datbuf = (__u8 *)data;
110 ops.oobbuf = (__u8 *)&pt1;
112 retval = mtd->write_oob(mtd, addr, &ops);
115 (TSTR("write_oob failed, chunk %d, mtd error %d"TENDSTR),
116 nand_chunk, retval));
118 return retval ? YAFFS_FAIL : YAFFS_OK;
121 /* Return with empty ExtendedTags but add ecc_result.
123 static int rettags(yaffs_ext_tags *etags, int ecc_result, int retval)
126 memset(etags, 0, sizeof(*etags));
127 etags->ecc_result = ecc_result;
132 /* Read a chunk (page) from NAND.
134 * Caller expects ExtendedTags data to be usable even on error; that is,
135 * all members except ecc_result and block_bad are zeroed.
137 * - Check ECC results for data (if applicable)
138 * - Check for blank/erased block (return empty ExtendedTags if blank)
139 * - Check the packed_tags1 mini-ECC (correct if necessary/possible)
140 * - Convert packed_tags1 to ExtendedTags
141 * - Update ecc_result and block_bad members to refect state.
143 * Returns YAFFS_OK or YAFFS_FAIL.
145 int nandmtd1_read_chunk_tags(yaffs_dev_t *dev,
146 int nand_chunk, __u8 *data, yaffs_ext_tags *etags)
148 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
149 int chunk_bytes = dev->data_bytes_per_chunk;
150 loff_t addr = ((loff_t)nand_chunk) * chunk_bytes;
151 int eccres = YAFFS_ECC_RESULT_NO_ERROR;
152 struct mtd_oob_ops ops;
153 yaffs_packed_tags1 pt1;
157 memset(&ops, 0, sizeof(ops));
158 ops.mode = MTD_OOB_AUTO;
159 ops.len = (data) ? chunk_bytes : 0;
160 ops.ooblen = YTAG1_SIZE;
162 ops.oobbuf = (__u8 *)&pt1;
164 /* Read page and oob using MTD.
165 * Check status and determine ECC result.
167 retval = mtd->read_oob(mtd, addr, &ops);
170 (TSTR("read_oob failed, chunk %d, mtd error %d"TENDSTR),
171 nand_chunk, retval));
180 /* MTD's ECC fixed the data */
181 eccres = YAFFS_ECC_RESULT_FIXED;
186 /* MTD's ECC could not fix the data */
187 dev->n_ecc_unfixed++;
190 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
191 etags->block_bad = (mtd->block_isbad)(mtd, addr);
195 /* Check for a blank/erased chunk.
197 if (yaffs_check_ff((__u8 *)&pt1, 8)) {
198 /* when blank, upper layers want ecc_result to be <= NO_ERROR */
199 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
202 #ifndef CONFIG_YAFFS_9BYTE_TAGS
203 /* Read deleted status (bit) then return it to it's non-deleted
204 * state before performing tags mini-ECC check. pt1.deleted is
207 deleted = !pt1.deleted;
210 deleted = (yaffs_count_bits(((__u8 *)&pt1)[8]) < 7);
213 /* Check the packed tags mini-ECC and correct if necessary/possible.
215 retval = yaffs_check_tags_ecc((yaffs_tags_t *)&pt1);
218 /* no tags error, use MTD result */
221 /* recovered tags-ECC error */
222 dev->n_tags_ecc_fixed++;
223 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
224 eccres = YAFFS_ECC_RESULT_FIXED;
227 /* unrecovered tags-ECC error */
228 dev->n_tags_ecc_unfixed++;
229 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
232 /* Unpack the tags to extended form and set ECC result.
233 * [set should_be_ff just to keep yaffs_unpack_tags1 happy]
235 pt1.should_be_ff = 0xFFFFFFFF;
236 yaffs_unpack_tags1(etags, &pt1);
237 etags->ecc_result = eccres;
239 /* Set deleted state */
240 etags->is_deleted = deleted;
246 * This is a persistant state.
247 * Use of this function should be rare.
249 * Returns YAFFS_OK or YAFFS_FAIL.
251 int nandmtd1_mark_block_bad(struct yaffs_dev_s *dev, int block_no)
253 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
254 int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
257 T(YAFFS_TRACE_BAD_BLOCKS,(TSTR("marking block %d bad"TENDSTR), block_no));
259 retval = mtd->block_markbad(mtd, (loff_t)blocksize * block_no);
260 return (retval) ? YAFFS_FAIL : YAFFS_OK;
263 /* Check any MTD prerequists.
265 * Returns YAFFS_OK or YAFFS_FAIL.
267 static int nandmtd1_test_prerequists(struct mtd_info *mtd)
269 /* 2.6.18 has mtd->ecclayout->oobavail */
270 /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
271 int oobavail = mtd->ecclayout->oobavail;
273 if (oobavail < YTAG1_SIZE) {
275 (TSTR("mtd device has only %d bytes for tags, need %d"TENDSTR),
276 oobavail, YTAG1_SIZE));
282 /* Query for the current state of a specific block.
284 * Examine the tags of the first chunk of the block and return the state:
285 * - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
286 * - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
287 * - YAFFS_BLOCK_STATE_EMPTY, the block is clean
289 * Always returns YAFFS_OK.
291 int nandmtd1_query_block(struct yaffs_dev_s *dev, int block_no,
292 yaffs_block_state_t *state_ptr, __u32 *seq_ptr)
294 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
295 int chunk_num = block_no * dev->param.chunks_per_block;
296 loff_t addr = (loff_t)chunk_num * dev->data_bytes_per_chunk;
297 yaffs_ext_tags etags;
298 int state = YAFFS_BLOCK_STATE_DEAD;
302 /* We don't yet have a good place to test for MTD config prerequists.
303 * Do it here as we are called during the initial scan.
305 if (nandmtd1_test_prerequists(mtd) != YAFFS_OK)
308 retval = nandmtd1_read_chunk_tags(dev, chunk_num, NULL, &etags);
309 etags.block_bad = (mtd->block_isbad)(mtd, addr);
310 if (etags.block_bad) {
311 T(YAFFS_TRACE_BAD_BLOCKS,
312 (TSTR("block %d is marked bad"TENDSTR), block_no));
313 state = YAFFS_BLOCK_STATE_DEAD;
314 } else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
315 /* bad tags, need to look more closely */
316 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
317 } else if (etags.chunk_used) {
318 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
319 seqnum = etags.seq_number;
321 state = YAFFS_BLOCK_STATE_EMPTY;
327 /* query always succeeds */