1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * This file provides ECC correction for more than 1 bit per block of data,
20  * struct nand_bch_control - private NAND BCH control structure
23  * @eccmask:   XOR ecc mask, allows erased pages to be decoded as valid
32  * nand_bch_calculate_ecc - [NAND Interface] Calculate ECC for data block
33  * @chip:	NAND chip object
35  * @code:	output buffer with ECC
40 	struct nand_bch_control *nbc = chip->ecc.priv;  in nand_bch_calculate_ecc()
43 	memset(code, 0, chip->ecc.bytes);  in nand_bch_calculate_ecc()
44 	bch_encode(nbc->bch, buf, chip->ecc.size, code);  in nand_bch_calculate_ecc()
47 	for (i = 0; i < chip->ecc.bytes; i++)  in nand_bch_calculate_ecc()
48 		code[i] ^= nbc->eccmask[i];  in nand_bch_calculate_ecc()
55  * nand_bch_correct_data - [NAND Interface] Detect and correct bit error(s)
56  * @chip:	NAND chip object
58  * @read_ecc:	ECC from the chip
59  * @calc_ecc:	the ECC calculated from raw data
66 	struct nand_bch_control *nbc = chip->ecc.priv;  in nand_bch_correct_data()
67 	unsigned int *errloc = nbc->errloc;  in nand_bch_correct_data()
70 	count = bch_decode(nbc->bch, NULL, chip->ecc.size, read_ecc, calc_ecc,  in nand_bch_correct_data()
74 			if (errloc[i] < (chip->ecc.size*8))  in nand_bch_correct_data()
77 			/* else error in ecc, no action needed */  in nand_bch_correct_data()
83 		pr_err("ecc unrecoverable error\n");  in nand_bch_correct_data()
84 		count = -EBADMSG;  in nand_bch_correct_data()
91  * nand_bch_init - [NAND Interface] Initialize NAND BCH error correction
95  *  a pointer to a new NAND BCH control structure, or NULL upon failure
97  * Initialize NAND BCH error correction. Parameters @eccsize and @eccbytes
100  * required to store m*t bits, where m is such that 2^m-1 > @eccsize*8.
103  * @eccsize = 512  (thus, m=13 is the smallest integer such that 2^m-1 > 512*8)
108 	struct nand_chip *nand = mtd_to_nand(mtd);  in nand_bch_init()  local
112 	unsigned int eccsize = nand->ecc.size;  in nand_bch_init()
113 	unsigned int eccbytes = nand->ecc.bytes;  in nand_bch_init()
114 	unsigned int eccstrength = nand->ecc.strength;  in nand_bch_init()
118 		nand->ecc.bytes = eccbytes;  in nand_bch_init()
122 		pr_warn("ecc parameters not supplied\n");  in nand_bch_init()
133 	nbc->bch = bch_init(m, t, 0, false);  in nand_bch_init()
134 	if (!nbc->bch)  in nand_bch_init()
138 	if (nbc->bch->ecc_bytes != eccbytes) {  in nand_bch_init()
140 			eccbytes, nbc->bch->ecc_bytes);  in nand_bch_init()
144 	eccsteps = mtd->writesize/eccsize;  in nand_bch_init()
147 	if (!mtd->ooblayout) {  in nand_bch_init()
159 	 * ecc->steps and ecc->total might be used by mtd->ooblayout->ecc(),  in nand_bch_init()
166 	nand->ecc.steps = eccsteps;  in nand_bch_init()
167 	nand->ecc.total = eccsteps * eccbytes;  in nand_bch_init()
168 	nand->base.ecc.ctx.total = nand->ecc.total;  in nand_bch_init()
170 		pr_warn("invalid ecc layout\n");  in nand_bch_init()
174 	nbc->eccmask = kzalloc(eccbytes, GFP_KERNEL);  in nand_bch_init()
175 	nbc->errloc = kmalloc_array(t, sizeof(*nbc->errloc), GFP_KERNEL);  in nand_bch_init()
176 	if (!nbc->eccmask || !nbc->errloc)  in nand_bch_init()
179 	 * compute and store the inverted ecc of an erased ecc block  in nand_bch_init()
186 	bch_encode(nbc->bch, erased_page, eccsize, nbc->eccmask);  in nand_bch_init()
190 		nbc->eccmask[i] ^= 0xff;  in nand_bch_init()
193 		nand->ecc.strength = (eccbytes * 8) / fls(8 * eccsize);  in nand_bch_init()
203  * nand_bch_free - [NAND Interface] Release NAND BCH ECC resources
204  * @nbc:	NAND BCH control structure
209 		bch_free(nbc->bch);  in nand_bch_free()
210 		kfree(nbc->errloc);  in nand_bch_free()
211 		kfree(nbc->eccmask);  in nand_bch_free()
219 MODULE_DESCRIPTION("NAND software BCH ECC support");