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"
33 #include "linux/kernel.h"
34 #include "linux/version.h"
35 #include "linux/types.h"
36 #include "linux/mtd/mtd.h"
38 #ifndef CONFIG_YAFFS_9BYTE_TAGS
44 /* Write a chunk (page) of data to NAND.
46 * Caller always provides ExtendedTags data which are converted to a more
47 * compact (packed) form for storage in NAND. A mini-ECC runs over the
48 * contents of the tags meta-data; used to valid the tags when read.
50 * - Pack ExtendedTags to packed_tags1 form
51 * - Compute mini-ECC for packed_tags1
52 * - Write data and packed tags to NAND.
54 * Note: Due to the use of the packed_tags1 meta-data which does not include
55 * a full sequence number (as found in the larger packed_tags2 form) it is
56 * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
57 * discarded and dirty. This is not ideal: newer NAND parts are supposed
58 * to be written just once. When Yaffs performs this operation, this
59 * function is called with a NULL data pointer -- calling MTD write_oob
60 * without data is valid usage (2.6.17).
62 * Any underlying MTD error results in YAFFS_FAIL.
63 * Returns YAFFS_OK or YAFFS_FAIL.
65 int nandmtd1_write_chunk_tags(struct yaffs_dev *dev,
66 int nand_chunk, const u8 *data,
67 const struct yaffs_ext_tags *etags)
69 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
70 int chunk_bytes = dev->data_bytes_per_chunk;
71 loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
72 struct mtd_oob_ops ops;
73 struct yaffs_packed_tags1 pt1;
76 /* we assume that packed_tags1 and struct yaffs_tags are compatible */
77 compile_time_assertion(sizeof(struct yaffs_packed_tags1) == 12);
78 compile_time_assertion(sizeof(struct yaffs_tags) == 8);
80 yaffs_pack_tags1(&pt1, etags);
81 yaffs_calc_tags_ecc((struct yaffs_tags *)&pt1);
83 /* When deleting a chunk, the upper layer provides only skeletal
84 * etags, one with is_deleted set. However, we need to update the
85 * tags, not erase them completely. So we use the NAND write property
86 * that only zeroed-bits stick and set tag bytes to all-ones and
87 * zero just the (not) deleted bit.
89 #ifndef CONFIG_YAFFS_9BYTE_TAGS
90 if (etags->is_deleted) {
91 memset(&pt1, 0xff, 8);
92 /* clear delete status bit to indicate deleted */
96 ((u8 *) &pt1)[8] = 0xff;
97 if (etags->is_deleted) {
98 memset(&pt1, 0xff, 8);
99 /* zero page_status byte to indicate deleted */
100 ((u8 *) &pt1)[8] = 0;
104 memset(&ops, 0, sizeof(ops));
105 ops.mode = MTD_OOB_AUTO;
106 ops.len = (data) ? chunk_bytes : 0;
107 ops.ooblen = YTAG1_SIZE;
108 ops.datbuf = (u8 *) data;
109 ops.oobbuf = (u8 *) &pt1;
111 retval = mtd->write_oob(mtd, addr, &ops);
113 yaffs_trace(YAFFS_TRACE_MTD,
114 "write_oob failed, chunk %d, mtd error %d",
117 return retval ? YAFFS_FAIL : YAFFS_OK;
120 /* Return with empty ExtendedTags but add ecc_result.
122 static int rettags(struct yaffs_ext_tags *etags, int ecc_result, int retval)
125 memset(etags, 0, sizeof(*etags));
126 etags->ecc_result = ecc_result;
131 /* Read a chunk (page) from NAND.
133 * Caller expects ExtendedTags data to be usable even on error; that is,
134 * all members except ecc_result and block_bad are zeroed.
136 * - Check ECC results for data (if applicable)
137 * - Check for blank/erased block (return empty ExtendedTags if blank)
138 * - Check the packed_tags1 mini-ECC (correct if necessary/possible)
139 * - Convert packed_tags1 to ExtendedTags
140 * - Update ecc_result and block_bad members to refect state.
142 * Returns YAFFS_OK or YAFFS_FAIL.
144 int nandmtd1_read_chunk_tags(struct yaffs_dev *dev,
145 int nand_chunk, u8 *data,
146 struct 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 struct 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);
169 yaffs_trace(YAFFS_TRACE_MTD,
170 "read_oob failed, chunk %d, mtd error %d",
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);
201 #ifndef CONFIG_YAFFS_9BYTE_TAGS
202 /* Read deleted status (bit) then return it to it's non-deleted
203 * state before performing tags mini-ECC check. pt1.deleted is
206 deleted = !pt1.deleted;
209 deleted = (hweight8(((u8 *) &pt1)[8]) < 7);
212 /* Check the packed tags mini-ECC and correct if necessary/possible.
214 retval = yaffs_check_tags_ecc((struct yaffs_tags *)&pt1);
217 /* no tags error, use MTD result */
220 /* recovered tags-ECC error */
221 dev->n_tags_ecc_fixed++;
222 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
223 eccres = YAFFS_ECC_RESULT_FIXED;
226 /* unrecovered tags-ECC error */
227 dev->n_tags_ecc_unfixed++;
228 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
231 /* Unpack the tags to extended form and set ECC result.
232 * [set should_be_ff just to keep yaffs_unpack_tags1 happy]
234 pt1.should_be_ff = 0xFFFFFFFF;
235 yaffs_unpack_tags1(etags, &pt1);
236 etags->ecc_result = eccres;
238 /* Set deleted state */
239 etags->is_deleted = deleted;
245 * This is a persistant state.
246 * Use of this function should be rare.
248 * Returns YAFFS_OK or YAFFS_FAIL.
250 int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no)
252 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
253 int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
256 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
257 "marking block %d bad", 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) {
274 yaffs_trace(YAFFS_TRACE_ERROR,
275 "mtd device has only %d bytes for tags, need %d",
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 *dev, int block_no,
292 enum yaffs_block_state *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 struct 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 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
312 "block %d is marked bad", 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 */