1 /*
2  *  linux/drivers/mtd/onenand/onenand_bbt.c
3  *
4  *  Bad Block Table support for the OneNAND driver
5  *
6  *  Copyright(c) 2005-2008 Samsung Electronics
7  *  Kyungmin Park <kyungmin.park@samsung.com>
8  *
9  *  TODO:
10  *    Split BBT core and chip specific BBT.
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU General Public License version 2 as
14  * published by the Free Software Foundation.
15  */
16 
17 #include <common.h>
18 #include <linux/compat.h>
19 #include <linux/mtd/mtd.h>
20 #include <linux/mtd/onenand.h>
21 #include <malloc.h>
22 
23 #include <asm/errno.h>
24 
25 /**
26  * check_short_pattern - [GENERIC] check if a pattern is in the buffer
27  * @param buf		the buffer to search
28  * @param len		the length of buffer to search
29  * @param paglen	the pagelength
30  * @param td		search pattern descriptor
31  *
32  * Check for a pattern at the given place. Used to search bad block
33  * tables and good / bad block identifiers. Same as check_pattern, but
34  * no optional empty check and the pattern is expected to start
35  * at offset 0.
36  */
37 static int check_short_pattern(uint8_t * buf, int len, int paglen,
38 			       struct nand_bbt_descr *td)
39 {
40 	int i;
41 	uint8_t *p = buf;
42 
43 	/* Compare the pattern */
44 	for (i = 0; i < td->len; i++) {
45 		if (p[i] != td->pattern[i])
46 			return -1;
47 	}
48 	return 0;
49 }
50 
51 /**
52  * create_bbt - [GENERIC] Create a bad block table by scanning the device
53  * @param mtd		MTD device structure
54  * @param buf		temporary buffer
55  * @param bd		descriptor for the good/bad block search pattern
56  * @param chip		create the table for a specific chip, -1 read all chips.
57  *              Applies only if NAND_BBT_PERCHIP option is set
58  *
59  * Create a bad block table by scanning the device
60  * for the given good/bad block identify pattern
61  */
62 static int create_bbt(struct mtd_info *mtd, uint8_t * buf,
63 		      struct nand_bbt_descr *bd, int chip)
64 {
65 	struct onenand_chip *this = mtd->priv;
66 	struct bbm_info *bbm = this->bbm;
67 	int i, j, numblocks, len, scanlen;
68 	int startblock;
69 	loff_t from;
70 	size_t readlen, ooblen;
71 	struct mtd_oob_ops ops;
72 	int rgn;
73 
74 	printk(KERN_INFO "Scanning device for bad blocks\n");
75 
76 	len = 1;
77 
78 	/* We need only read few bytes from the OOB area */
79 	scanlen = ooblen = 0;
80 	readlen = bd->len;
81 
82 	/* chip == -1 case only */
83 	/* Note that numblocks is 2 * (real numblocks) here;
84 	 * see i += 2 below as it makses shifting and masking less painful
85 	 */
86 	numblocks = this->chipsize >> (bbm->bbt_erase_shift - 1);
87 	startblock = 0;
88 	from = 0;
89 
90 	ops.mode = MTD_OPS_PLACE_OOB;
91 	ops.ooblen = readlen;
92 	ops.oobbuf = buf;
93 	ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
94 
95 	for (i = startblock; i < numblocks;) {
96 		int ret;
97 
98 		for (j = 0; j < len; j++) {
99 			/* No need to read pages fully,
100 			 * just read required OOB bytes */
101 			ret = onenand_bbt_read_oob(mtd,
102 					     from + j * mtd->writesize +
103 					     bd->offs, &ops);
104 
105 			/* If it is a initial bad block, just ignore it */
106 			if (ret == ONENAND_BBT_READ_FATAL_ERROR)
107 				return -EIO;
108 
109 			if (ret || check_short_pattern
110 			    (&buf[j * scanlen], scanlen, mtd->writesize, bd)) {
111 				bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
112 				printk(KERN_WARNING
113 				       "Bad eraseblock %d at 0x%08x\n", i >> 1,
114 				       (unsigned int)from);
115 				break;
116 			}
117 		}
118 		i += 2;
119 
120 		if (FLEXONENAND(this)) {
121 			rgn = flexonenand_region(mtd, from);
122 			from += mtd->eraseregions[rgn].erasesize;
123 		} else
124 			from += (1 << bbm->bbt_erase_shift);
125 	}
126 
127 	return 0;
128 }
129 
130 /**
131  * onenand_memory_bbt - [GENERIC] create a memory based bad block table
132  * @param mtd		MTD device structure
133  * @param bd		descriptor for the good/bad block search pattern
134  *
135  * The function creates a memory based bbt by scanning the device
136  * for manufacturer / software marked good / bad blocks
137  */
138 static inline int onenand_memory_bbt(struct mtd_info *mtd,
139 				     struct nand_bbt_descr *bd)
140 {
141 	unsigned char data_buf[MAX_ONENAND_PAGESIZE];
142 
143 	bd->options &= ~NAND_BBT_SCANEMPTY;
144 	return create_bbt(mtd, data_buf, bd, -1);
145 }
146 
147 /**
148  * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
149  * @param mtd		MTD device structure
150  * @param offs		offset in the device
151  * @param allowbbt	allow access to bad block table region
152  */
153 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
154 {
155 	struct onenand_chip *this = mtd->priv;
156 	struct bbm_info *bbm = this->bbm;
157 	int block;
158 	uint8_t res;
159 
160 	/* Get block number * 2 */
161 	block = (int) (onenand_block(this, offs) << 1);
162 	res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
163 
164 	MTDDEBUG (MTD_DEBUG_LEVEL2,
165 		"onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
166 		(unsigned int)offs, block >> 1, res);
167 
168 	switch ((int)res) {
169 	case 0x00:
170 		return 0;
171 	case 0x01:
172 		return 1;
173 	case 0x02:
174 		return allowbbt ? 0 : 1;
175 	}
176 
177 	return 1;
178 }
179 
180 /**
181  * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
182  * @param mtd		MTD device structure
183  * @param bd		descriptor for the good/bad block search pattern
184  *
185  * The function checks, if a bad block table(s) is/are already
186  * available. If not it scans the device for manufacturer
187  * marked good / bad blocks and writes the bad block table(s) to
188  * the selected place.
189  *
190  * The bad block table memory is allocated here. It must be freed
191  * by calling the onenand_free_bbt function.
192  *
193  */
194 int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
195 {
196 	struct onenand_chip *this = mtd->priv;
197 	struct bbm_info *bbm = this->bbm;
198 	int len, ret = 0;
199 
200 	len = this->chipsize >> (this->erase_shift + 2);
201 	/* Allocate memory (2bit per block) */
202 	bbm->bbt = malloc(len);
203 	if (!bbm->bbt)
204 		return -ENOMEM;
205 	/* Clear the memory bad block table */
206 	memset(bbm->bbt, 0x00, len);
207 
208 	/* Set the bad block position */
209 	bbm->badblockpos = ONENAND_BADBLOCK_POS;
210 
211 	/* Set erase shift */
212 	bbm->bbt_erase_shift = this->erase_shift;
213 
214 	if (!bbm->isbad_bbt)
215 		bbm->isbad_bbt = onenand_isbad_bbt;
216 
217 	/* Scan the device to build a memory based bad block table */
218 	if ((ret = onenand_memory_bbt(mtd, bd))) {
219 		printk(KERN_ERR
220 		       "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
221 		free(bbm->bbt);
222 		bbm->bbt = NULL;
223 	}
224 
225 	return ret;
226 }
227 
228 /*
229  * Define some generic bad / good block scan pattern which are used
230  * while scanning a device for factory marked good / bad blocks.
231  */
232 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
233 
234 static struct nand_bbt_descr largepage_memorybased = {
235 	.options = 0,
236 	.offs = 0,
237 	.len = 2,
238 	.pattern = scan_ff_pattern,
239 };
240 
241 /**
242  * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
243  * @param mtd		MTD device structure
244  *
245  * This function selects the default bad block table
246  * support for the device and calls the onenand_scan_bbt function
247  */
248 int onenand_default_bbt(struct mtd_info *mtd)
249 {
250 	struct onenand_chip *this = mtd->priv;
251 	struct bbm_info *bbm;
252 
253 	this->bbm = malloc(sizeof(struct bbm_info));
254 	if (!this->bbm)
255 		return -ENOMEM;
256 
257 	bbm = this->bbm;
258 
259 	memset(bbm, 0, sizeof(struct bbm_info));
260 
261 	/* 1KB page has same configuration as 2KB page */
262 	if (!bbm->badblock_pattern)
263 		bbm->badblock_pattern = &largepage_memorybased;
264 
265 	return onenand_scan_bbt(mtd, bbm->badblock_pattern);
266 }
267