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 /* Don't compile this module if we don't have MTD's mtd_oob_ops interface */
40 #if (MTD_VERSION_CODE > MTD_VERSION(2, 6, 17))
42 #ifndef CONFIG_YAFFS_9BYTE_TAGS
49 /* Use the following nand_ecclayout with MTD when using
50 * CONFIG_YAFFS_9BYTE_TAGS and the older on-NAND tags layout.
51 * If you have existing Yaffs images and the byte order differs from this,
52 * adjust 'oobfree' to match your existing Yaffs data.
54 * This nand_ecclayout scatters/gathers to/from the old-yaffs layout with the
55 * page_status byte (at NAND spare offset 4) scattered/gathered from/to
58 * Old-style on-NAND format: T0,T1,T2,T3,P,B,T4,T5,E0,E1,E2,T6,T7,E3,E4,E5
59 * We have/need packed_tags1 plus page_status: T0,T1,T2,T3,T4,T5,T6,T7,P
60 * where Tn are the tag bytes, En are MTD's ECC bytes, P is the page_status
61 * byte and B is the small-page bad-block indicator byte.
63 static struct nand_ecclayout nand_oob_16 = {
65 .eccpos = {8, 9, 10, 13, 14, 15},
67 .oobfree = {{0, 4}, {6, 2}, {11, 2}, {4, 1}}
71 /* Write a chunk (page) of data to NAND.
73 * Caller always provides ExtendedTags data which are converted to a more
74 * compact (packed) form for storage in NAND. A mini-ECC runs over the
75 * contents of the tags meta-data; used to valid the tags when read.
77 * - Pack ExtendedTags to packed_tags1 form
78 * - Compute mini-ECC for packed_tags1
79 * - Write data and packed tags to NAND.
81 * Note: Due to the use of the packed_tags1 meta-data which does not include
82 * a full sequence number (as found in the larger packed_tags2 form) it is
83 * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
84 * discarded and dirty. This is not ideal: newer NAND parts are supposed
85 * to be written just once. When Yaffs performs this operation, this
86 * function is called with a NULL data pointer -- calling MTD write_oob
87 * without data is valid usage (2.6.17).
89 * Any underlying MTD error results in YAFFS_FAIL.
90 * Returns YAFFS_OK or YAFFS_FAIL.
92 int nandmtd1_write_chunk_tags(struct yaffs_dev *dev,
93 int nand_chunk, const u8 * data,
94 const struct yaffs_ext_tags *etags)
96 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
97 int chunk_bytes = dev->data_bytes_per_chunk;
98 loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
99 struct mtd_oob_ops ops;
100 struct yaffs_packed_tags1 pt1;
103 /* we assume that packed_tags1 and struct yaffs_tags are compatible */
104 compile_time_assertion(sizeof(struct yaffs_packed_tags1) == 12);
105 compile_time_assertion(sizeof(struct yaffs_tags) == 8);
107 yaffs_pack_tags1(&pt1, etags);
108 yaffs_calc_tags_ecc((struct yaffs_tags *)&pt1);
110 /* When deleting a chunk, the upper layer provides only skeletal
111 * etags, one with is_deleted set. However, we need to update the
112 * tags, not erase them completely. So we use the NAND write property
113 * that only zeroed-bits stick and set tag bytes to all-ones and
114 * zero just the (not) deleted bit.
116 #ifndef CONFIG_YAFFS_9BYTE_TAGS
117 if (etags->is_deleted) {
118 memset(&pt1, 0xff, 8);
119 /* clear delete status bit to indicate deleted */
123 ((u8 *) & pt1)[8] = 0xff;
124 if (etags->is_deleted) {
125 memset(&pt1, 0xff, 8);
126 /* zero page_status byte to indicate deleted */
127 ((u8 *) & pt1)[8] = 0;
131 memset(&ops, 0, sizeof(ops));
132 ops.mode = MTD_OOB_AUTO;
133 ops.len = (data) ? chunk_bytes : 0;
134 ops.ooblen = YTAG1_SIZE;
135 ops.datbuf = (u8 *) data;
136 ops.oobbuf = (u8 *) & pt1;
138 retval = mtd->write_oob(mtd, addr, &ops);
141 (TSTR("write_oob failed, chunk %d, mtd error %d" TENDSTR),
142 nand_chunk, retval));
144 return retval ? YAFFS_FAIL : YAFFS_OK;
147 /* Return with empty ExtendedTags but add ecc_result.
149 static int rettags(struct yaffs_ext_tags *etags, int ecc_result, int retval)
152 memset(etags, 0, sizeof(*etags));
153 etags->ecc_result = ecc_result;
158 /* Read a chunk (page) from NAND.
160 * Caller expects ExtendedTags data to be usable even on error; that is,
161 * all members except ecc_result and block_bad are zeroed.
163 * - Check ECC results for data (if applicable)
164 * - Check for blank/erased block (return empty ExtendedTags if blank)
165 * - Check the packed_tags1 mini-ECC (correct if necessary/possible)
166 * - Convert packed_tags1 to ExtendedTags
167 * - Update ecc_result and block_bad members to refect state.
169 * Returns YAFFS_OK or YAFFS_FAIL.
171 int nandmtd1_read_chunk_tags(struct yaffs_dev *dev,
172 int nand_chunk, u8 * data,
173 struct yaffs_ext_tags *etags)
175 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
176 int chunk_bytes = dev->data_bytes_per_chunk;
177 loff_t addr = ((loff_t) nand_chunk) * chunk_bytes;
178 int eccres = YAFFS_ECC_RESULT_NO_ERROR;
179 struct mtd_oob_ops ops;
180 struct yaffs_packed_tags1 pt1;
184 memset(&ops, 0, sizeof(ops));
185 ops.mode = MTD_OOB_AUTO;
186 ops.len = (data) ? chunk_bytes : 0;
187 ops.ooblen = YTAG1_SIZE;
189 ops.oobbuf = (u8 *) & pt1;
191 #if (MTD_VERSION_CODE < MTD_VERSION(2, 6, 20))
192 /* In MTD 2.6.18 to 2.6.19 nand_base.c:nand_do_read_oob() has a bug;
193 * help it out with ops.len = ops.ooblen when ops.datbuf == NULL.
195 ops.len = (ops.datbuf) ? ops.len : ops.ooblen;
197 /* Read page and oob using MTD.
198 * Check status and determine ECC result.
200 retval = mtd->read_oob(mtd, addr, &ops);
203 (TSTR("read_oob failed, chunk %d, mtd error %d" TENDSTR),
204 nand_chunk, retval));
213 /* MTD's ECC fixed the data */
214 eccres = YAFFS_ECC_RESULT_FIXED;
219 /* MTD's ECC could not fix the data */
220 dev->n_ecc_unfixed++;
223 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
224 etags->block_bad = (mtd->block_isbad) (mtd, addr);
228 /* Check for a blank/erased chunk.
230 if (yaffs_check_ff((u8 *) & pt1, 8)) {
231 /* when blank, upper layers want ecc_result to be <= NO_ERROR */
232 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
234 #ifndef CONFIG_YAFFS_9BYTE_TAGS
235 /* Read deleted status (bit) then return it to it's non-deleted
236 * state before performing tags mini-ECC check. pt1.deleted is
239 deleted = !pt1.deleted;
242 deleted = (yaffs_count_bits(((u8 *) & pt1)[8]) < 7);
245 /* Check the packed tags mini-ECC and correct if necessary/possible.
247 retval = yaffs_check_tags_ecc((struct yaffs_tags *)&pt1);
250 /* no tags error, use MTD result */
253 /* recovered tags-ECC error */
254 dev->n_tags_ecc_fixed++;
255 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
256 eccres = YAFFS_ECC_RESULT_FIXED;
259 /* unrecovered tags-ECC error */
260 dev->n_tags_ecc_unfixed++;
261 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
264 /* Unpack the tags to extended form and set ECC result.
265 * [set should_be_ff just to keep yaffs_unpack_tags1 happy]
267 pt1.should_be_ff = 0xFFFFFFFF;
268 yaffs_unpack_tags1(etags, &pt1);
269 etags->ecc_result = eccres;
271 /* Set deleted state */
272 etags->is_deleted = deleted;
278 * This is a persistant state.
279 * Use of this function should be rare.
281 * Returns YAFFS_OK or YAFFS_FAIL.
283 int nandmtd1_mark_block_bad(struct yaffs_dev *dev, int block_no)
285 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
286 int blocksize = dev->param.chunks_per_block * dev->data_bytes_per_chunk;
289 T(YAFFS_TRACE_BAD_BLOCKS,
290 (TSTR("marking block %d bad" TENDSTR), block_no));
292 retval = mtd->block_markbad(mtd, (loff_t) blocksize * block_no);
293 return (retval) ? YAFFS_FAIL : YAFFS_OK;
296 /* Check any MTD prerequists.
298 * Returns YAFFS_OK or YAFFS_FAIL.
300 static int nandmtd1_test_prerequists(struct mtd_info *mtd)
302 /* 2.6.18 has mtd->ecclayout->oobavail */
303 /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
304 int oobavail = mtd->ecclayout->oobavail;
306 if (oobavail < YTAG1_SIZE) {
309 ("mtd device has only %d bytes for tags, need %d" TENDSTR),
310 oobavail, YTAG1_SIZE));
316 /* Query for the current state of a specific block.
318 * Examine the tags of the first chunk of the block and return the state:
319 * - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
320 * - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
321 * - YAFFS_BLOCK_STATE_EMPTY, the block is clean
323 * Always returns YAFFS_OK.
325 int nandmtd1_query_block(struct yaffs_dev *dev, int block_no,
326 enum yaffs_block_state *state_ptr, u32 * seq_ptr)
328 struct mtd_info *mtd = yaffs_dev_to_mtd(dev);
329 int chunk_num = block_no * dev->param.chunks_per_block;
330 loff_t addr = (loff_t) chunk_num * dev->data_bytes_per_chunk;
331 struct yaffs_ext_tags etags;
332 int state = YAFFS_BLOCK_STATE_DEAD;
336 /* We don't yet have a good place to test for MTD config prerequists.
337 * Do it here as we are called during the initial scan.
339 if (nandmtd1_test_prerequists(mtd) != YAFFS_OK)
342 retval = nandmtd1_read_chunk_tags(dev, chunk_num, NULL, &etags);
343 etags.block_bad = (mtd->block_isbad) (mtd, addr);
344 if (etags.block_bad) {
345 T(YAFFS_TRACE_BAD_BLOCKS,
346 (TSTR("block %d is marked bad" TENDSTR), block_no));
347 state = YAFFS_BLOCK_STATE_DEAD;
348 } else if (etags.ecc_result != YAFFS_ECC_RESULT_NO_ERROR) {
349 /* bad tags, need to look more closely */
350 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
351 } else if (etags.chunk_used) {
352 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
353 seqnum = etags.seq_number;
355 state = YAFFS_BLOCK_STATE_EMPTY;
361 /* query always succeeds */
365 #endif /*MTD_VERSION */