1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Bad Block Table support for the OneNAND driver
4 *
5 * Copyright(c) 2005 Samsung Electronics
6 * Kyungmin Park <kyungmin.park@samsung.com>
7 *
8 * Derived from nand_bbt.c
9 *
10 * TODO:
11 * Split BBT core and chip specific BBT.
12 */
13
14 #include <linux/slab.h>
15 #include <linux/mtd/mtd.h>
16 #include <linux/mtd/onenand.h>
17 #include <linux/export.h>
18
19 /**
20 * check_short_pattern - [GENERIC] check if a pattern is in the buffer
21 * @param buf the buffer to search
22 * @param len the length of buffer to search
23 * @param paglen the pagelength
24 * @param td search pattern descriptor
25 *
26 * Check for a pattern at the given place. Used to search bad block
27 * tables and good / bad block identifiers. Same as check_pattern, but
28 * no optional empty check and the pattern is expected to start
29 * at offset 0.
30 *
31 */
32 static int check_short_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
33 {
34 int i;
35 uint8_t *p = buf;
36
37 /* Compare the pattern */
38 for (i = 0; i < td->len; i++) {
39 if (p[i] != td->pattern[i])
40 return -1;
41 }
42 return 0;
43 }
44
45 /**
46 * create_bbt - [GENERIC] Create a bad block table by scanning the device
47 * @param mtd MTD device structure
48 * @param buf temporary buffer
49 * @param bd descriptor for the good/bad block search pattern
50 * @param chip create the table for a specific chip, -1 read all chips.
51 * Applies only if NAND_BBT_PERCHIP option is set
52 *
53 * Create a bad block table by scanning the device
54 * for the given good/bad block identify pattern
55 */
56 static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd, int chip)
57 {
58 struct onenand_chip *this = mtd->priv;
59 struct bbm_info *bbm = this->bbm;
60 int i, j, numblocks, len, scanlen;
61 int startblock;
62 loff_t from;
63 size_t readlen, ooblen;
64 struct mtd_oob_ops ops;
65 int rgn;
66
67 printk(KERN_INFO "Scanning device for bad blocks\n");
68
69 len = 2;
70
71 /* We need only read few bytes from the OOB area */
72 scanlen = ooblen = 0;
73 readlen = bd->len;
74
75 /* chip == -1 case only */
76 /* Note that numblocks is 2 * (real numblocks) here;
77 * see i += 2 below as it makses shifting and masking less painful
78 */
79 numblocks = this->chipsize >> (bbm->bbt_erase_shift - 1);
80 startblock = 0;
81 from = 0;
82
83 ops.mode = MTD_OPS_PLACE_OOB;
84 ops.ooblen = readlen;
85 ops.oobbuf = buf;
86 ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
87
88 for (i = startblock; i < numblocks; ) {
89 int ret;
90
91 for (j = 0; j < len; j++) {
92 /* No need to read pages fully,
93 * just read required OOB bytes */
94 ret = onenand_bbt_read_oob(mtd,
95 from + j * this->writesize + bd->offs, &ops);
96
97 /* If it is a initial bad block, just ignore it */
98 if (ret == ONENAND_BBT_READ_FATAL_ERROR)
99 return -EIO;
100
101 if (ret || check_short_pattern(&buf[j * scanlen],
102 scanlen, this->writesize, bd)) {
103 bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
104 printk(KERN_INFO "OneNAND eraseblock %d is an "
105 "initial bad block\n", i >> 1);
106 mtd->ecc_stats.badblocks++;
107 break;
108 }
109 }
110 i += 2;
111
112 if (FLEXONENAND(this)) {
113 rgn = flexonenand_region(mtd, from);
114 from += mtd->eraseregions[rgn].erasesize;
115 } else
116 from += (1 << bbm->bbt_erase_shift);
117 }
118
119 return 0;
120 }
121
122
123 /**
124 * onenand_memory_bbt - [GENERIC] create a memory based bad block table
125 * @param mtd MTD device structure
126 * @param bd descriptor for the good/bad block search pattern
127 *
128 * The function creates a memory based bbt by scanning the device
129 * for manufacturer / software marked good / bad blocks
130 */
131 static inline int onenand_memory_bbt (struct mtd_info *mtd, struct nand_bbt_descr *bd)
132 {
133 struct onenand_chip *this = mtd->priv;
134
135 return create_bbt(mtd, this->page_buf, bd, -1);
136 }
137
138 /**
139 * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
140 * @param mtd MTD device structure
141 * @param offs offset in the device
142 * @param allowbbt allow access to bad block table region
143 */
144 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
145 {
146 struct onenand_chip *this = mtd->priv;
147 struct bbm_info *bbm = this->bbm;
148 int block;
149 uint8_t res;
150
151 /* Get block number * 2 */
152 block = (int) (onenand_block(this, offs) << 1);
153 res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
154
155 pr_debug("onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
156 (unsigned int) offs, block >> 1, res);
157
158 switch ((int) res) {
159 case 0x00: return 0;
160 case 0x01: return 1;
161 case 0x02: return allowbbt ? 0 : 1;
162 }
163
164 return 1;
165 }
166
167 /**
168 * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
169 * @param mtd MTD device structure
170 * @param bd descriptor for the good/bad block search pattern
171 *
172 * The function checks, if a bad block table(s) is/are already
173 * available. If not it scans the device for manufacturer
174 * marked good / bad blocks and writes the bad block table(s) to
175 * the selected place.
176 *
177 * The bad block table memory is allocated here. It is freed
178 * by the onenand_release function.
179 *
180 */
181 static int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
182 {
183 struct onenand_chip *this = mtd->priv;
184 struct bbm_info *bbm = this->bbm;
185 int len, ret = 0;
186
187 len = this->chipsize >> (this->erase_shift + 2);
188 /* Allocate memory (2bit per block) and clear the memory bad block table */
189 bbm->bbt = kzalloc(len, GFP_KERNEL);
190 if (!bbm->bbt)
191 return -ENOMEM;
192
193 /* Set erase shift */
194 bbm->bbt_erase_shift = this->erase_shift;
195
196 if (!bbm->isbad_bbt)
197 bbm->isbad_bbt = onenand_isbad_bbt;
198
199 /* Scan the device to build a memory based bad block table */
200 if ((ret = onenand_memory_bbt(mtd, bd))) {
201 printk(KERN_ERR "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
202 kfree(bbm->bbt);
203 bbm->bbt = NULL;
204 }
205
206 return ret;
207 }
208
209 /*
210 * Define some generic bad / good block scan pattern which are used
211 * while scanning a device for factory marked good / bad blocks.
212 */
213 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
214
215 static struct nand_bbt_descr largepage_memorybased = {
216 .options = 0,
217 .offs = 0,
218 .len = 2,
219 .pattern = scan_ff_pattern,
220 };
221
222 /**
223 * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
224 * @param mtd MTD device structure
225 *
226 * This function selects the default bad block table
227 * support for the device and calls the onenand_scan_bbt function
228 */
229 int onenand_default_bbt(struct mtd_info *mtd)
230 {
231 struct onenand_chip *this = mtd->priv;
232 struct bbm_info *bbm;
233
234 this->bbm = kzalloc(sizeof(struct bbm_info), GFP_KERNEL);
235 if (!this->bbm)
236 return -ENOMEM;
237
238 bbm = this->bbm;
239
240 /* 1KB page has same configuration as 2KB page */
241 if (!bbm->badblock_pattern)
242 bbm->badblock_pattern = &largepage_memorybased;
243
244 return onenand_scan_bbt(mtd, bbm->badblock_pattern);
245 }