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Christian Hitz55f7bca2011-10-12 09:31:59 +02001/*
2 * This file provides ECC correction for more than 1 bit per block of data,
3 * using binary BCH codes. It relies on the generic BCH library lib/bch.c.
4 *
5 * Copyright © 2011 Ivan Djelic <ivan.djelic@parrot.com>
6 *
Wolfgang Denkd79de1d2013-07-08 09:37:19 +02007 * SPDX-License-Identifier: GPL-2.0+
Christian Hitz55f7bca2011-10-12 09:31:59 +02008 */
9
10#include <common.h>
11/*#include <asm/io.h>*/
12#include <linux/types.h>
13
14#include <linux/bitops.h>
15#include <linux/mtd/mtd.h>
Masahiro Yamada2b7a8732017-11-30 13:45:24 +090016#include <linux/mtd/rawnand.h>
Christian Hitz55f7bca2011-10-12 09:31:59 +020017#include <linux/mtd/nand_bch.h>
18#include <linux/bch.h>
19#include <malloc.h>
20
21/**
22 * struct nand_bch_control - private NAND BCH control structure
23 * @bch: BCH control structure
24 * @ecclayout: private ecc layout for this BCH configuration
25 * @errloc: error location array
26 * @eccmask: XOR ecc mask, allows erased pages to be decoded as valid
27 */
28struct nand_bch_control {
29 struct bch_control *bch;
30 struct nand_ecclayout ecclayout;
31 unsigned int *errloc;
32 unsigned char *eccmask;
33};
34
35/**
36 * nand_bch_calculate_ecc - [NAND Interface] Calculate ECC for data block
37 * @mtd: MTD block structure
38 * @buf: input buffer with raw data
39 * @code: output buffer with ECC
40 */
41int nand_bch_calculate_ecc(struct mtd_info *mtd, const unsigned char *buf,
42 unsigned char *code)
43{
Scott Wood17fed142016-05-30 13:57:56 -050044 const struct nand_chip *chip = mtd_to_nand(mtd);
Christian Hitz55f7bca2011-10-12 09:31:59 +020045 struct nand_bch_control *nbc = chip->ecc.priv;
46 unsigned int i;
47
48 memset(code, 0, chip->ecc.bytes);
49 encode_bch(nbc->bch, buf, chip->ecc.size, code);
50
51 /* apply mask so that an erased page is a valid codeword */
52 for (i = 0; i < chip->ecc.bytes; i++)
53 code[i] ^= nbc->eccmask[i];
54
55 return 0;
56}
57
58/**
59 * nand_bch_correct_data - [NAND Interface] Detect and correct bit error(s)
60 * @mtd: MTD block structure
61 * @buf: raw data read from the chip
62 * @read_ecc: ECC from the chip
63 * @calc_ecc: the ECC calculated from raw data
64 *
65 * Detect and correct bit errors for a data byte block
66 */
67int nand_bch_correct_data(struct mtd_info *mtd, unsigned char *buf,
68 unsigned char *read_ecc, unsigned char *calc_ecc)
69{
Scott Wood17fed142016-05-30 13:57:56 -050070 const struct nand_chip *chip = mtd_to_nand(mtd);
Christian Hitz55f7bca2011-10-12 09:31:59 +020071 struct nand_bch_control *nbc = chip->ecc.priv;
72 unsigned int *errloc = nbc->errloc;
73 int i, count;
74
75 count = decode_bch(nbc->bch, NULL, chip->ecc.size, read_ecc, calc_ecc,
76 NULL, errloc);
77 if (count > 0) {
78 for (i = 0; i < count; i++) {
79 if (errloc[i] < (chip->ecc.size*8))
80 /* error is located in data, correct it */
81 buf[errloc[i] >> 3] ^= (1 << (errloc[i] & 7));
82 /* else error in ecc, no action needed */
83
Masahiro Yamadaf8a5d512017-10-18 00:10:48 +090084 pr_debug("%s: corrected bitflip %u\n",
85 __func__, errloc[i]);
Christian Hitz55f7bca2011-10-12 09:31:59 +020086 }
87 } else if (count < 0) {
88 printk(KERN_ERR "ecc unrecoverable error\n");
Scott Wood52ab7ce2016-05-30 13:57:58 -050089 count = -EBADMSG;
Christian Hitz55f7bca2011-10-12 09:31:59 +020090 }
91 return count;
92}
93
94/**
95 * nand_bch_init - [NAND Interface] Initialize NAND BCH error correction
96 * @mtd: MTD block structure
Christian Hitz55f7bca2011-10-12 09:31:59 +020097 *
98 * Returns:
99 * a pointer to a new NAND BCH control structure, or NULL upon failure
100 *
101 * Initialize NAND BCH error correction. Parameters @eccsize and @eccbytes
102 * are used to compute BCH parameters m (Galois field order) and t (error
103 * correction capability). @eccbytes should be equal to the number of bytes
104 * required to store m*t bits, where m is such that 2^m-1 > @eccsize*8.
105 *
106 * Example: to configure 4 bit correction per 512 bytes, you should pass
107 * @eccsize = 512 (thus, m=13 is the smallest integer such that 2^m-1 > 512*8)
108 * @eccbytes = 7 (7 bytes are required to store m*t = 13*4 = 52 bits)
109 */
Scott Wood52ab7ce2016-05-30 13:57:58 -0500110struct nand_bch_control *nand_bch_init(struct mtd_info *mtd)
Christian Hitz55f7bca2011-10-12 09:31:59 +0200111{
Scott Wood52ab7ce2016-05-30 13:57:58 -0500112 struct nand_chip *nand = mtd_to_nand(mtd);
Christian Hitz55f7bca2011-10-12 09:31:59 +0200113 unsigned int m, t, eccsteps, i;
Scott Wood52ab7ce2016-05-30 13:57:58 -0500114 struct nand_ecclayout *layout = nand->ecc.layout;
Christian Hitz55f7bca2011-10-12 09:31:59 +0200115 struct nand_bch_control *nbc = NULL;
116 unsigned char *erased_page;
Scott Wood52ab7ce2016-05-30 13:57:58 -0500117 unsigned int eccsize = nand->ecc.size;
118 unsigned int eccbytes = nand->ecc.bytes;
119 unsigned int eccstrength = nand->ecc.strength;
120
121 if (!eccbytes && eccstrength) {
122 eccbytes = DIV_ROUND_UP(eccstrength * fls(8 * eccsize), 8);
123 nand->ecc.bytes = eccbytes;
124 }
Christian Hitz55f7bca2011-10-12 09:31:59 +0200125
126 if (!eccsize || !eccbytes) {
127 printk(KERN_WARNING "ecc parameters not supplied\n");
128 goto fail;
129 }
130
131 m = fls(1+8*eccsize);
132 t = (eccbytes*8)/m;
133
134 nbc = kzalloc(sizeof(*nbc), GFP_KERNEL);
135 if (!nbc)
136 goto fail;
137
138 nbc->bch = init_bch(m, t, 0);
139 if (!nbc->bch)
140 goto fail;
141
142 /* verify that eccbytes has the expected value */
143 if (nbc->bch->ecc_bytes != eccbytes) {
144 printk(KERN_WARNING "invalid eccbytes %u, should be %u\n",
145 eccbytes, nbc->bch->ecc_bytes);
146 goto fail;
147 }
148
149 eccsteps = mtd->writesize/eccsize;
150
151 /* if no ecc placement scheme was provided, build one */
Scott Wood52ab7ce2016-05-30 13:57:58 -0500152 if (!layout) {
Christian Hitz55f7bca2011-10-12 09:31:59 +0200153
154 /* handle large page devices only */
155 if (mtd->oobsize < 64) {
156 printk(KERN_WARNING "must provide an oob scheme for "
157 "oobsize %d\n", mtd->oobsize);
158 goto fail;
159 }
160
161 layout = &nbc->ecclayout;
162 layout->eccbytes = eccsteps*eccbytes;
163
164 /* reserve 2 bytes for bad block marker */
165 if (layout->eccbytes+2 > mtd->oobsize) {
166 printk(KERN_WARNING "no suitable oob scheme available "
167 "for oobsize %d eccbytes %u\n", mtd->oobsize,
168 eccbytes);
169 goto fail;
170 }
171 /* put ecc bytes at oob tail */
172 for (i = 0; i < layout->eccbytes; i++)
173 layout->eccpos[i] = mtd->oobsize-layout->eccbytes+i;
174
175 layout->oobfree[0].offset = 2;
176 layout->oobfree[0].length = mtd->oobsize-2-layout->eccbytes;
177
Scott Wood52ab7ce2016-05-30 13:57:58 -0500178 nand->ecc.layout = layout;
Christian Hitz55f7bca2011-10-12 09:31:59 +0200179 }
180
181 /* sanity checks */
182 if (8*(eccsize+eccbytes) >= (1 << m)) {
183 printk(KERN_WARNING "eccsize %u is too large\n", eccsize);
184 goto fail;
185 }
Scott Wood52ab7ce2016-05-30 13:57:58 -0500186 if (layout->eccbytes != (eccsteps*eccbytes)) {
Christian Hitz55f7bca2011-10-12 09:31:59 +0200187 printk(KERN_WARNING "invalid ecc layout\n");
188 goto fail;
189 }
190
191 nbc->eccmask = kmalloc(eccbytes, GFP_KERNEL);
192 nbc->errloc = kmalloc(t*sizeof(*nbc->errloc), GFP_KERNEL);
193 if (!nbc->eccmask || !nbc->errloc)
194 goto fail;
195 /*
196 * compute and store the inverted ecc of an erased ecc block
197 */
198 erased_page = kmalloc(eccsize, GFP_KERNEL);
199 if (!erased_page)
200 goto fail;
201
202 memset(erased_page, 0xff, eccsize);
203 memset(nbc->eccmask, 0, eccbytes);
204 encode_bch(nbc->bch, erased_page, eccsize, nbc->eccmask);
205 kfree(erased_page);
206
207 for (i = 0; i < eccbytes; i++)
208 nbc->eccmask[i] ^= 0xff;
209
Scott Wood52ab7ce2016-05-30 13:57:58 -0500210 if (!eccstrength)
211 nand->ecc.strength = (eccbytes * 8) / fls(8 * eccsize);
212
Christian Hitz55f7bca2011-10-12 09:31:59 +0200213 return nbc;
214fail:
215 nand_bch_free(nbc);
216 return NULL;
217}
218
219/**
220 * nand_bch_free - [NAND Interface] Release NAND BCH ECC resources
221 * @nbc: NAND BCH control structure
222 */
223void nand_bch_free(struct nand_bch_control *nbc)
224{
225 if (nbc) {
226 free_bch(nbc->bch);
227 kfree(nbc->errloc);
228 kfree(nbc->eccmask);
229 kfree(nbc);
230 }
231}