Root/drivers/mtd/onenand/onenand_bbt.c

1/*
2 * linux/drivers/mtd/onenand/onenand_bbt.c
3 *
4 * Bad Block Table support for the OneNAND driver
5 *
6 * Copyright(c) 2005 Samsung Electronics
7 * Kyungmin Park <kyungmin.park@samsung.com>
8 *
9 * Derived from nand_bbt.c
10 *
11 * TODO:
12 * Split BBT core and chip specific BBT.
13 */
14
15#include <linux/slab.h>
16#include <linux/mtd/mtd.h>
17#include <linux/mtd/onenand.h>
18#include <linux/export.h>
19
20/**
21 * check_short_pattern - [GENERIC] check if a pattern is in the buffer
22 * @param buf the buffer to search
23 * @param len the length of buffer to search
24 * @param paglen the pagelength
25 * @param td search pattern descriptor
26 *
27 * Check for a pattern at the given place. Used to search bad block
28 * tables and good / bad block identifiers. Same as check_pattern, but
29 * no optional empty check and the pattern is expected to start
30 * at offset 0.
31 *
32 */
33static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
34{
35    int i;
36    uint8_t *p = buf;
37
38    /* Compare the pattern */
39    for (i = 0; i < td->len; i++) {
40        if (p[i] != td->pattern[i])
41            return -1;
42    }
43        return 0;
44}
45
46/**
47 * create_bbt - [GENERIC] Create a bad block table by scanning the device
48 * @param mtd MTD device structure
49 * @param buf temporary buffer
50 * @param bd descriptor for the good/bad block search pattern
51 * @param chip create the table for a specific chip, -1 read all chips.
52 * Applies only if NAND_BBT_PERCHIP option is set
53 *
54 * Create a bad block table by scanning the device
55 * for the given good/bad block identify pattern
56 */
57static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
58{
59    struct onenand_chip *this = mtd->priv;
60    struct bbm_info *bbm = this->bbm;
61    int i, j, numblocks, len, scanlen;
62    int startblock;
63    loff_t from;
64    size_t readlen, ooblen;
65    struct mtd_oob_ops ops;
66    int rgn;
67
68    printk(KERN_INFO "Scanning device for bad blocks\n");
69
70    len = 2;
71
72    /* We need only read few bytes from the OOB area */
73    scanlen = ooblen = 0;
74    readlen = bd->len;
75
76    /* chip == -1 case only */
77    /* Note that numblocks is 2 * (real numblocks) here;
78     * see i += 2 below as it makses shifting and masking less painful
79     */
80    numblocks = this->chipsize >> (bbm->bbt_erase_shift - 1);
81    startblock = 0;
82    from = 0;
83
84    ops.mode = MTD_OPS_PLACE_OOB;
85    ops.ooblen = readlen;
86    ops.oobbuf = buf;
87    ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
88
89    for (i = startblock; i < numblocks; ) {
90        int ret;
91
92        for (j = 0; j < len; j++) {
93            /* No need to read pages fully,
94             * just read required OOB bytes */
95            ret = onenand_bbt_read_oob(mtd,
96                from + j * this->writesize + bd->offs, &ops);
97
98            /* If it is a initial bad block, just ignore it */
99            if (ret == ONENAND_BBT_READ_FATAL_ERROR)
100                return -EIO;
101
102            if (ret || check_short_pattern(&buf[j * scanlen],
103                           scanlen, this->writesize, bd)) {
104                bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
105                printk(KERN_INFO "OneNAND eraseblock %d is an "
106                    "initial bad block\n", i >> 1);
107                mtd->ecc_stats.badblocks++;
108                break;
109            }
110        }
111        i += 2;
112
113        if (FLEXONENAND(this)) {
114            rgn = flexonenand_region(mtd, from);
115            from += mtd->eraseregions[rgn].erasesize;
116        } else
117            from += (1 << bbm->bbt_erase_shift);
118    }
119
120    return 0;
121}
122
123
124/**
125 * onenand_memory_bbt - [GENERIC] create a memory based bad block table
126 * @param mtd MTD device structure
127 * @param bd descriptor for the good/bad block search pattern
128 *
129 * The function creates a memory based bbt by scanning the device
130 * for manufacturer / software marked good / bad blocks
131 */
132static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
133{
134    struct onenand_chip *this = mtd->priv;
135
136        bd->options &= ~NAND_BBT_SCANEMPTY;
137    return create_bbt(mtd, this->page_buf, bd, -1);
138}
139
140/**
141 * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
142 * @param mtd MTD device structure
143 * @param offs offset in the device
144 * @param allowbbt allow access to bad block table region
145 */
146static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
147{
148    struct onenand_chip *this = mtd->priv;
149    struct bbm_info *bbm = this->bbm;
150    int block;
151    uint8_t res;
152
153    /* Get block number * 2 */
154    block = (int) (onenand_block(this, offs) << 1);
155    res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
156
157    pr_debug("onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
158        (unsigned int) offs, block >> 1, res);
159
160    switch ((int) res) {
161    case 0x00: return 0;
162    case 0x01: return 1;
163    case 0x02: return allowbbt ? 0 : 1;
164    }
165
166    return 1;
167}
168
169/**
170 * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
171 * @param mtd MTD device structure
172 * @param bd descriptor for the good/bad block search pattern
173 *
174 * The function checks, if a bad block table(s) is/are already
175 * available. If not it scans the device for manufacturer
176 * marked good / bad blocks and writes the bad block table(s) to
177 * the selected place.
178 *
179 * The bad block table memory is allocated here. It is freed
180 * by the onenand_release function.
181 *
182 */
183int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
184{
185    struct onenand_chip *this = mtd->priv;
186    struct bbm_info *bbm = this->bbm;
187    int len, ret = 0;
188
189    len = this->chipsize >> (this->erase_shift + 2);
190    /* Allocate memory (2bit per block) and clear the memory bad block table */
191    bbm->bbt = kzalloc(len, GFP_KERNEL);
192    if (!bbm->bbt)
193        return -ENOMEM;
194
195    /* Set the bad block position */
196    bbm->badblockpos = ONENAND_BADBLOCK_POS;
197
198    /* Set erase shift */
199    bbm->bbt_erase_shift = this->erase_shift;
200
201    if (!bbm->isbad_bbt)
202        bbm->isbad_bbt = onenand_isbad_bbt;
203
204    /* Scan the device to build a memory based bad block table */
205    if ((ret = onenand_memory_bbt(mtd, bd))) {
206        printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
207        kfree(bbm->bbt);
208        bbm->bbt = NULL;
209    }
210
211    return ret;
212}
213
214/*
215 * Define some generic bad / good block scan pattern which are used
216 * while scanning a device for factory marked good / bad blocks.
217 */
218static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
219
220static struct nand_bbt_descr largepage_memorybased = {
221    .options = 0,
222    .offs = 0,
223    .len = 2,
224    .pattern = scan_ff_pattern,
225};
226
227/**
228 * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
229 * @param mtd MTD device structure
230 *
231 * This function selects the default bad block table
232 * support for the device and calls the onenand_scan_bbt function
233 */
234int onenand_default_bbt(struct mtd_info *mtd)
235{
236    struct onenand_chip *this = mtd->priv;
237    struct bbm_info *bbm;
238
239    this->bbm = kzalloc(sizeof(struct bbm_info), GFP_KERNEL);
240    if (!this->bbm)
241        return -ENOMEM;
242
243    bbm = this->bbm;
244
245    /* 1KB page has same configuration as 2KB page */
246    if (!bbm->badblock_pattern)
247        bbm->badblock_pattern = &largepage_memorybased;
248
249    return onenand_scan_bbt(mtd, bbm->badblock_pattern);
250}
251
252EXPORT_SYMBOL(onenand_scan_bbt);
253EXPORT_SYMBOL(onenand_default_bbt);
254

Archive Download this file



interactive