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/mtd/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 
73 	printk(KERN_INFO "Scanning device for bad blocks\n");
74 
75 	len = 1;
76 
77 	/* We need only read few bytes from the OOB area */
78 	scanlen = ooblen = 0;
79 	readlen = bd->len;
80 
81 	/* chip == -1 case only */
82 	/* Note that numblocks is 2 * (real numblocks) here;
83 	 * see i += 2 below as it makses shifting and masking less painful
84 	 */
85 	numblocks = mtd->size >> (bbm->bbt_erase_shift - 1);
86 	startblock = 0;
87 	from = 0;
88 
89 	ops.mode = MTD_OOB_PLACE;
90 	ops.ooblen = readlen;
91 	ops.oobbuf = buf;
92 	ops.len = ops.ooboffs = ops.retlen = ops.oobretlen = 0;
93 
94 	for (i = startblock; i < numblocks;) {
95 		int ret;
96 
97 		for (j = 0; j < len; j++) {
98 			/* No need to read pages fully,
99 			 * just read required OOB bytes */
100 			ret = onenand_bbt_read_oob(mtd,
101 					     from + j * mtd->writesize +
102 					     bd->offs, &ops);
103 
104 			/* If it is a initial bad block, just ignore it */
105 			if (ret == ONENAND_BBT_READ_FATAL_ERROR)
106 				return -EIO;
107 
108 			if (ret || check_short_pattern
109 			    (&buf[j * scanlen], scanlen, mtd->writesize, bd)) {
110 				bbm->bbt[i >> 3] |= 0x03 << (i & 0x6);
111 				printk(KERN_WARNING
112 				       "Bad eraseblock %d at 0x%08x\n", i >> 1,
113 				       (unsigned int)from);
114 				break;
115 			}
116 		}
117 		i += 2;
118 		from += (1 << bbm->bbt_erase_shift);
119 	}
120 
121 	return 0;
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  */
132 static inline int onenand_memory_bbt(struct mtd_info *mtd,
133 				     struct nand_bbt_descr *bd)
134 {
135 	unsigned char data_buf[MAX_ONENAND_PAGESIZE];
136 
137 	bd->options &= ~NAND_BBT_SCANEMPTY;
138 	return create_bbt(mtd, data_buf, bd, -1);
139 }
140 
141 /**
142  * onenand_isbad_bbt - [OneNAND Interface] Check if a block is bad
143  * @param mtd		MTD device structure
144  * @param offs		offset in the device
145  * @param allowbbt	allow access to bad block table region
146  */
147 static int onenand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
148 {
149 	struct onenand_chip *this = mtd->priv;
150 	struct bbm_info *bbm = this->bbm;
151 	int block;
152 	uint8_t res;
153 
154 	/* Get block number * 2 */
155 	block = (int)(offs >> (bbm->bbt_erase_shift - 1));
156 	res = (bbm->bbt[block >> 3] >> (block & 0x06)) & 0x03;
157 
158 	MTDDEBUG (MTD_DEBUG_LEVEL2,
159 		"onenand_isbad_bbt: bbt info for offs 0x%08x: (block %d) 0x%02x\n",
160 		(unsigned int)offs, block >> 1, res);
161 
162 	switch ((int)res) {
163 	case 0x00:
164 		return 0;
165 	case 0x01:
166 		return 1;
167 	case 0x02:
168 		return allowbbt ? 0 : 1;
169 	}
170 
171 	return 1;
172 }
173 
174 /**
175  * onenand_scan_bbt - [OneNAND Interface] scan, find, read and maybe create bad block table(s)
176  * @param mtd		MTD device structure
177  * @param bd		descriptor for the good/bad block search pattern
178  *
179  * The function checks, if a bad block table(s) is/are already
180  * available. If not it scans the device for manufacturer
181  * marked good / bad blocks and writes the bad block table(s) to
182  * the selected place.
183  *
184  * The bad block table memory is allocated here. It must be freed
185  * by calling the onenand_free_bbt function.
186  *
187  */
188 int onenand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
189 {
190 	struct onenand_chip *this = mtd->priv;
191 	struct bbm_info *bbm = this->bbm;
192 	int len, ret = 0;
193 
194 	len = mtd->size >> (this->erase_shift + 2);
195 	/* Allocate memory (2bit per block) */
196 	bbm->bbt = malloc(len);
197 	if (!bbm->bbt) {
198 		printk(KERN_ERR "onenand_scan_bbt: Out of memory\n");
199 		return -ENOMEM;
200 	}
201 	/* Clear the memory bad block table */
202 	memset(bbm->bbt, 0x00, len);
203 
204 	/* Set the bad block position */
205 	bbm->badblockpos = ONENAND_BADBLOCK_POS;
206 
207 	/* Set erase shift */
208 	bbm->bbt_erase_shift = this->erase_shift;
209 
210 	if (!bbm->isbad_bbt)
211 		bbm->isbad_bbt = onenand_isbad_bbt;
212 
213 	/* Scan the device to build a memory based bad block table */
214 	if ((ret = onenand_memory_bbt(mtd, bd))) {
215 		printk(KERN_ERR
216 		       "onenand_scan_bbt: Can't scan flash and build the RAM-based BBT\n");
217 		free(bbm->bbt);
218 		bbm->bbt = NULL;
219 	}
220 
221 	return ret;
222 }
223 
224 /*
225  * Define some generic bad / good block scan pattern which are used
226  * while scanning a device for factory marked good / bad blocks.
227  */
228 static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
229 
230 static struct nand_bbt_descr largepage_memorybased = {
231 	.options = 0,
232 	.offs = 0,
233 	.len = 2,
234 	.pattern = scan_ff_pattern,
235 };
236 
237 /**
238  * onenand_default_bbt - [OneNAND Interface] Select a default bad block table for the device
239  * @param mtd		MTD device structure
240  *
241  * This function selects the default bad block table
242  * support for the device and calls the onenand_scan_bbt function
243  */
244 int onenand_default_bbt(struct mtd_info *mtd)
245 {
246 	struct onenand_chip *this = mtd->priv;
247 	struct bbm_info *bbm;
248 
249 	this->bbm = malloc(sizeof(struct bbm_info));
250 	if (!this->bbm)
251 		return -ENOMEM;
252 
253 	bbm = this->bbm;
254 
255 	memset(bbm, 0, sizeof(struct bbm_info));
256 
257 	/* 1KB page has same configuration as 2KB page */
258 	if (!bbm->badblock_pattern)
259 		bbm->badblock_pattern = &largepage_memorybased;
260 
261 	return onenand_scan_bbt(mtd, bbm->badblock_pattern);
262 }
263