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  * @buf:		the buffer to search
22  * @len:		the length of buffer to search
23  * @paglen:	the pagelength
24  * @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  * @mtd:		MTD device structure
48  * @buf:		temporary buffer
49  * @bd:		descriptor for the good/bad block search pattern
50  * @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  * @mtd:		MTD device structure
126  * @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  * @mtd:		MTD device structure
141  * @offs:		offset in the device
142  * @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  * @mtd:		MTD device structure
170  * @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  * @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 }
246