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 */
32static 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 */
56static 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;
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 = 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 */
131static 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 */
144static 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 */
181static 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 */
213static uint8_t scan_ff_pattern[] = { 0xff, 0xff };
214
215static 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 */
229int 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