1 /*
2 * YAFFS: Yet another FFS. A NAND-flash specific file system.
3 * yaffs_mtdif1.c NAND mtd interface functions for small-page NAND.
4 *
5 * Copyright (C) 2002 Aleph One Ltd.
6 * for Toby Churchill Ltd and Brightstar Engineering
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13 /*
14 * This module provides the interface between yaffs_nand.c and the
15 * MTD API. This version is used when the MTD interface supports the
16 * 'mtd_oob_ops' style calls to read_oob and write_oob, circa 2.6.17,
17 * and we have small-page NAND device.
18 *
19 * These functions are invoked via function pointers in yaffs_nand.c.
20 * This replaces functionality provided by functions in yaffs_mtdif.c
21 * and the yaffs_TagsCompatability functions in yaffs_tagscompat.c that are
22 * called in yaffs_mtdif.c when the function pointers are NULL.
23 * We assume the MTD layer is performing ECC (useNANDECC is true).
24 */
25
26 #include "yportenv.h"
27 #include "yaffs_guts.h"
28 #include "yaffs_packedtags1.h"
29 #include "yaffs_tagscompat.h" /* for yaffs_CalcTagsECC */
30
31 #include "linux/kernel.h"
32 #include "linux/version.h"
33 #include "linux/types.h"
34 #include "linux/mtd/mtd.h"
35
36 /* Don't compile this module if we don't have MTD's mtd_oob_ops interface */
37 #if (MTD_VERSION_CODE > MTD_VERSION(2, 6, 17))
38
39 const char *yaffs_mtdif1_c_version = "$Id$";
40
41 #ifndef CONFIG_YAFFS_9BYTE_TAGS
42 # define YTAG1_SIZE 8
43 #else
44 # define YTAG1_SIZE 9
45 #endif
46
47 #if 0
48 /* Use the following nand_ecclayout with MTD when using
49 * CONFIG_YAFFS_9BYTE_TAGS and the older on-NAND tags layout.
50 * If you have existing Yaffs images and the byte order differs from this,
51 * adjust 'oobfree' to match your existing Yaffs data.
52 *
53 * This nand_ecclayout scatters/gathers to/from the old-yaffs layout with the
54 * pageStatus byte (at NAND spare offset 4) scattered/gathered from/to
55 * the 9th byte.
56 *
57 * Old-style on-NAND format: T0,T1,T2,T3,P,B,T4,T5,E0,E1,E2,T6,T7,E3,E4,E5
58 * We have/need PackedTags1 plus pageStatus: T0,T1,T2,T3,T4,T5,T6,T7,P
59 * where Tn are the tag bytes, En are MTD's ECC bytes, P is the pageStatus
60 * byte and B is the small-page bad-block indicator byte.
61 */
62 static struct nand_ecclayout nand_oob_16 = {
63 .eccbytes = 6,
64 .eccpos = { 8, 9, 10, 13, 14, 15 },
65 .oobavail = 9,
66 .oobfree = { { 0, 4 }, { 6, 2 }, { 11, 2 }, { 4, 1 } }
67 };
68 #endif
69
70 /* Write a chunk (page) of data to NAND.
71 *
72 * Caller always provides ExtendedTags data which are converted to a more
73 * compact (packed) form for storage in NAND. A mini-ECC runs over the
74 * contents of the tags meta-data; used to valid the tags when read.
75 *
76 * - Pack ExtendedTags to PackedTags1 form
77 * - Compute mini-ECC for PackedTags1
78 * - Write data and packed tags to NAND.
79 *
80 * Note: Due to the use of the PackedTags1 meta-data which does not include
81 * a full sequence number (as found in the larger PackedTags2 form) it is
82 * necessary for Yaffs to re-write a chunk/page (just once) to mark it as
83 * discarded and dirty. This is not ideal: newer NAND parts are supposed
84 * to be written just once. When Yaffs performs this operation, this
85 * function is called with a NULL data pointer -- calling MTD write_oob
86 * without data is valid usage (2.6.17).
87 *
88 * Any underlying MTD error results in YAFFS_FAIL.
89 * Returns YAFFS_OK or YAFFS_FAIL.
90 */
nandmtd1_WriteChunkWithTagsToNAND(yaffs_Device * dev,int chunkInNAND,const __u8 * data,const yaffs_ExtendedTags * etags)91 int nandmtd1_WriteChunkWithTagsToNAND(yaffs_Device *dev,
92 int chunkInNAND, const __u8 *data, const yaffs_ExtendedTags *etags)
93 {
94 struct mtd_info *mtd = dev->genericDevice;
95 int chunkBytes = dev->nDataBytesPerChunk;
96 loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
97 struct mtd_oob_ops ops;
98 yaffs_PackedTags1 pt1;
99 int retval;
100
101 /* we assume that PackedTags1 and yaffs_Tags are compatible */
102 compile_time_assertion(sizeof(yaffs_PackedTags1) == 12);
103 compile_time_assertion(sizeof(yaffs_Tags) == 8);
104
105 yaffs_PackTags1(&pt1, etags);
106 yaffs_CalcTagsECC((yaffs_Tags *)&pt1);
107
108 /* When deleting a chunk, the upper layer provides only skeletal
109 * etags, one with chunkDeleted set. However, we need to update the
110 * tags, not erase them completely. So we use the NAND write property
111 * that only zeroed-bits stick and set tag bytes to all-ones and
112 * zero just the (not) deleted bit.
113 */
114 #ifndef CONFIG_YAFFS_9BYTE_TAGS
115 if (etags->chunkDeleted) {
116 memset(&pt1, 0xff, 8);
117 /* clear delete status bit to indicate deleted */
118 pt1.deleted = 0;
119 }
120 #else
121 ((__u8 *)&pt1)[8] = 0xff;
122 if (etags->chunkDeleted) {
123 memset(&pt1, 0xff, 8);
124 /* zero pageStatus byte to indicate deleted */
125 ((__u8 *)&pt1)[8] = 0;
126 }
127 #endif
128
129 memset(&ops, 0, sizeof(ops));
130 ops.mode = MTD_OOB_AUTO;
131 ops.len = (data) ? chunkBytes : 0;
132 ops.ooblen = YTAG1_SIZE;
133 ops.datbuf = (__u8 *)data;
134 ops.oobbuf = (__u8 *)&pt1;
135
136 retval = mtd->write_oob(mtd, addr, &ops);
137 if (retval) {
138 yaffs_trace(YAFFS_TRACE_MTD,
139 "write_oob failed, chunk %d, mtd error %d\n",
140 chunkInNAND, retval);
141 }
142 return retval ? YAFFS_FAIL : YAFFS_OK;
143 }
144
145 /* Return with empty ExtendedTags but add eccResult.
146 */
rettags(yaffs_ExtendedTags * etags,int eccResult,int retval)147 static int rettags(yaffs_ExtendedTags *etags, int eccResult, int retval)
148 {
149 if (etags) {
150 memset(etags, 0, sizeof(*etags));
151 etags->eccResult = eccResult;
152 }
153 return retval;
154 }
155
156 /* Read a chunk (page) from NAND.
157 *
158 * Caller expects ExtendedTags data to be usable even on error; that is,
159 * all members except eccResult and blockBad are zeroed.
160 *
161 * - Check ECC results for data (if applicable)
162 * - Check for blank/erased block (return empty ExtendedTags if blank)
163 * - Check the PackedTags1 mini-ECC (correct if necessary/possible)
164 * - Convert PackedTags1 to ExtendedTags
165 * - Update eccResult and blockBad members to refect state.
166 *
167 * Returns YAFFS_OK or YAFFS_FAIL.
168 */
nandmtd1_ReadChunkWithTagsFromNAND(yaffs_Device * dev,int chunkInNAND,__u8 * data,yaffs_ExtendedTags * etags)169 int nandmtd1_ReadChunkWithTagsFromNAND(yaffs_Device *dev,
170 int chunkInNAND, __u8 *data, yaffs_ExtendedTags *etags)
171 {
172 struct mtd_info *mtd = dev->genericDevice;
173 int chunkBytes = dev->nDataBytesPerChunk;
174 loff_t addr = ((loff_t)chunkInNAND) * chunkBytes;
175 int eccres = YAFFS_ECC_RESULT_NO_ERROR;
176 struct mtd_oob_ops ops;
177 yaffs_PackedTags1 pt1;
178 int retval;
179 int deleted;
180
181 memset(&ops, 0, sizeof(ops));
182 ops.mode = MTD_OOB_AUTO;
183 ops.len = (data) ? chunkBytes : 0;
184 ops.ooblen = YTAG1_SIZE;
185 ops.datbuf = data;
186 ops.oobbuf = (__u8 *)&pt1;
187
188 #if (MTD_VERSION_CODE < MTD_VERSION(2, 6, 20))
189 /* In MTD 2.6.18 to 2.6.19 nand_base.c:nand_do_read_oob() has a bug;
190 * help it out with ops.len = ops.ooblen when ops.datbuf == NULL.
191 */
192 ops.len = (ops.datbuf) ? ops.len : ops.ooblen;
193 #endif
194 /* Read page and oob using MTD.
195 * Check status and determine ECC result.
196 */
197 retval = mtd->read_oob(mtd, addr, &ops);
198 if (retval) {
199 yaffs_trace(YAFFS_TRACE_MTD,
200 "read_oob failed, chunk %d, mtd error %d\n",
201 chunkInNAND, retval);
202 }
203
204 switch (retval) {
205 case 0:
206 /* no error */
207 break;
208
209 case -EUCLEAN:
210 /* MTD's ECC fixed the data */
211 eccres = YAFFS_ECC_RESULT_FIXED;
212 dev->eccFixed++;
213 break;
214
215 case -EBADMSG:
216 /* MTD's ECC could not fix the data */
217 dev->eccUnfixed++;
218 /* fall into... */
219 default:
220 rettags(etags, YAFFS_ECC_RESULT_UNFIXED, 0);
221 etags->blockBad = (mtd->block_isbad)(mtd, addr);
222 return YAFFS_FAIL;
223 }
224
225 /* Check for a blank/erased chunk.
226 */
227 if (yaffs_CheckFF((__u8 *)&pt1, 8)) {
228 /* when blank, upper layers want eccResult to be <= NO_ERROR */
229 return rettags(etags, YAFFS_ECC_RESULT_NO_ERROR, YAFFS_OK);
230 }
231
232 #ifndef CONFIG_YAFFS_9BYTE_TAGS
233 /* Read deleted status (bit) then return it to it's non-deleted
234 * state before performing tags mini-ECC check. pt1.deleted is
235 * inverted.
236 */
237 deleted = !pt1.deleted;
238 pt1.deleted = 1;
239 #else
240 deleted = (yaffs_CountBits(((__u8 *)&pt1)[8]) < 7);
241 #endif
242
243 /* Check the packed tags mini-ECC and correct if necessary/possible.
244 */
245 retval = yaffs_CheckECCOnTags((yaffs_Tags *)&pt1);
246 switch (retval) {
247 case 0:
248 /* no tags error, use MTD result */
249 break;
250 case 1:
251 /* recovered tags-ECC error */
252 dev->tagsEccFixed++;
253 if (eccres == YAFFS_ECC_RESULT_NO_ERROR)
254 eccres = YAFFS_ECC_RESULT_FIXED;
255 break;
256 default:
257 /* unrecovered tags-ECC error */
258 dev->tagsEccUnfixed++;
259 return rettags(etags, YAFFS_ECC_RESULT_UNFIXED, YAFFS_FAIL);
260 }
261
262 /* Unpack the tags to extended form and set ECC result.
263 * [set shouldBeFF just to keep yaffs_UnpackTags1 happy]
264 */
265 pt1.shouldBeFF = 0xFFFFFFFF;
266 yaffs_UnpackTags1(etags, &pt1);
267 etags->eccResult = eccres;
268
269 /* Set deleted state */
270 etags->chunkDeleted = deleted;
271 return YAFFS_OK;
272 }
273
274 /* Mark a block bad.
275 *
276 * This is a persistant state.
277 * Use of this function should be rare.
278 *
279 * Returns YAFFS_OK or YAFFS_FAIL.
280 */
nandmtd1_MarkNANDBlockBad(struct yaffs_DeviceStruct * dev,int blockNo)281 int nandmtd1_MarkNANDBlockBad(struct yaffs_DeviceStruct *dev, int blockNo)
282 {
283 struct mtd_info *mtd = dev->genericDevice;
284 int blocksize = dev->nChunksPerBlock * dev->nDataBytesPerChunk;
285 int retval;
286
287 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS, "marking block %d bad\n", blockNo);
288
289 retval = mtd->block_markbad(mtd, (loff_t)blocksize * blockNo);
290 return (retval) ? YAFFS_FAIL : YAFFS_OK;
291 }
292
293 /* Check any MTD prerequists.
294 *
295 * Returns YAFFS_OK or YAFFS_FAIL.
296 */
nandmtd1_TestPrerequists(struct mtd_info * mtd)297 static int nandmtd1_TestPrerequists(struct mtd_info *mtd)
298 {
299 /* 2.6.18 has mtd->ecclayout->oobavail */
300 /* 2.6.21 has mtd->ecclayout->oobavail and mtd->oobavail */
301 int oobavail = mtd->ecclayout->oobavail;
302
303 if (oobavail < YTAG1_SIZE) {
304 yaffs_trace(YAFFS_TRACE_ERROR,
305 "mtd device has only %d bytes for tags, need %d\n",
306 oobavail, YTAG1_SIZE);
307 return YAFFS_FAIL;
308 }
309 return YAFFS_OK;
310 }
311
312 /* Query for the current state of a specific block.
313 *
314 * Examine the tags of the first chunk of the block and return the state:
315 * - YAFFS_BLOCK_STATE_DEAD, the block is marked bad
316 * - YAFFS_BLOCK_STATE_NEEDS_SCANNING, the block is in use
317 * - YAFFS_BLOCK_STATE_EMPTY, the block is clean
318 *
319 * Always returns YAFFS_OK.
320 */
nandmtd1_QueryNANDBlock(struct yaffs_DeviceStruct * dev,int blockNo,yaffs_BlockState * pState,__u32 * pSequenceNumber)321 int nandmtd1_QueryNANDBlock(struct yaffs_DeviceStruct *dev, int blockNo,
322 yaffs_BlockState *pState, __u32 *pSequenceNumber)
323 {
324 struct mtd_info *mtd = dev->genericDevice;
325 int chunkNo = blockNo * dev->nChunksPerBlock;
326 loff_t addr = (loff_t)chunkNo * dev->nDataBytesPerChunk;
327 yaffs_ExtendedTags etags;
328 int state = YAFFS_BLOCK_STATE_DEAD;
329 int seqnum = 0;
330 int retval;
331
332 /* We don't yet have a good place to test for MTD config prerequists.
333 * Do it here as we are called during the initial scan.
334 */
335 if (nandmtd1_TestPrerequists(mtd) != YAFFS_OK)
336 return YAFFS_FAIL;
337
338 retval = nandmtd1_ReadChunkWithTagsFromNAND(dev, chunkNo, NULL, &etags);
339 etags.blockBad = (mtd->block_isbad)(mtd, addr);
340 if (etags.blockBad) {
341 yaffs_trace(YAFFS_TRACE_BAD_BLOCKS,
342 "block %d is marked bad\n", blockNo);
343 state = YAFFS_BLOCK_STATE_DEAD;
344 } else if (etags.eccResult != YAFFS_ECC_RESULT_NO_ERROR) {
345 /* bad tags, need to look more closely */
346 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
347 } else if (etags.chunkUsed) {
348 state = YAFFS_BLOCK_STATE_NEEDS_SCANNING;
349 seqnum = etags.sequenceNumber;
350 } else {
351 state = YAFFS_BLOCK_STATE_EMPTY;
352 }
353
354 *pState = state;
355 *pSequenceNumber = seqnum;
356
357 /* query always succeeds */
358 return YAFFS_OK;
359 }
360
361 #endif /*MTD_VERSION*/
362