Commit 9994bb3f authored by Miquel Raynal's avatar Miquel Raynal
Browse files

mtd: nand: ecc-bch: Create the software BCH engine 



Let's continue introducing the generic ECC engine abstraction in the
NAND subsystem by instantiating a first ECC engine: the software
BCH one.

While at it, make a very tidy ecc_sw_bch_init() function and move all
the sanity checks and user input management in
nand_ecc_sw_bch_init_ctx(). This second helper will be called from the
raw RAND core.

Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200929230124.31491-10-miquel.raynal@bootlin.com
parent 80fe6031

drivers/mtd/nand/ecc-sw-bch.c

+270 −63
Original line number Diff line number Diff line
@@ -75,6 +75,19 @@ int nand_ecc_sw_bch_correct(struct nand_device *nand, unsigned char *buf, 
}

EXPORT_SYMBOL(nand_ecc_sw_bch_correct);



/**

 * nand_ecc_sw_bch_cleanup - Cleanup software BCH ECC resources

 * @nand: NAND device

 */

static void nand_ecc_sw_bch_cleanup(struct nand_device *nand)

{

	struct nand_ecc_sw_bch_conf *engine_conf = nand->ecc.ctx.priv;



	bch_free(engine_conf->bch);

	kfree(engine_conf->errloc);

	kfree(engine_conf->eccmask);

}



/**

 * nand_ecc_sw_bch_init - Initialize software BCH ECC engine

 * @nand: NAND device
@@ -92,71 +105,36 @@ EXPORT_SYMBOL(nand_ecc_sw_bch_correct); 
 * step_size = 512 (thus, m = 13 is the smallest integer such that 2^m - 1 > 512 * 8)

 * bytes = 7 (7 bytes are required to store m * t = 13 * 4 = 52 bits)

 */

int nand_ecc_sw_bch_init(struct nand_device *nand)

static int nand_ecc_sw_bch_init(struct nand_device *nand)

{

	struct mtd_info *mtd = nanddev_to_mtd(nand);

	unsigned int m, t, eccsteps, i;

	struct nand_ecc_sw_bch_conf *engine_conf = nand->ecc.ctx.priv;

	unsigned char *erased_page;

	unsigned int eccsize = nand->ecc.ctx.conf.step_size;

	unsigned int eccbytes = engine_conf->code_size;

	unsigned int eccstrength = nand->ecc.ctx.conf.strength;



	if (!eccbytes && eccstrength) {

		eccbytes = DIV_ROUND_UP(eccstrength * fls(8 * eccsize), 8);

		engine_conf->code_size = eccbytes;

	}



	if (!eccsize || !eccbytes) {

		pr_warn("ecc parameters not supplied\n");

		return -EINVAL;

	}

	unsigned int m, t, i;

	unsigned char *erased_page;

	int ret;



	m = fls(1+8*eccsize);

	m = fls(1 + (8 * eccsize));

	t = (eccbytes * 8) / m;



	engine_conf->bch = bch_init(m, t, 0, false);

	if (!engine_conf->bch)

		return -EINVAL;



	/* verify that eccbytes has the expected value */

	if (engine_conf->bch->ecc_bytes != eccbytes) {

		pr_warn("invalid eccbytes %u, should be %u\n",

			eccbytes, engine_conf->bch->ecc_bytes);

		goto fail;

	}



	eccsteps = mtd->writesize/eccsize;



	/* Check that we have an oob layout description. */

	if (!mtd->ooblayout) {

		pr_warn("missing oob scheme");

		goto fail;

	}



	/* sanity checks */

	if (8*(eccsize+eccbytes) >= (1 << m)) {

		pr_warn("eccsize %u is too large\n", eccsize);

		goto fail;

	}



	if (mtd_ooblayout_count_eccbytes(mtd) != (eccsteps*eccbytes)) {

		pr_warn("invalid ecc layout\n");

		goto fail;

	}



	engine_conf->eccmask = kzalloc(eccbytes, GFP_KERNEL);

	engine_conf->errloc = kmalloc_array(t, sizeof(*engine_conf->errloc),

					    GFP_KERNEL);

	if (!engine_conf->eccmask || !engine_conf->errloc)

		goto fail;

	if (!engine_conf->eccmask || !engine_conf->errloc) {

		ret = -ENOMEM;

		goto cleanup;

	}



	/*

	 * compute and store the inverted ecc of an erased ecc block

	 */

	/* Compute and store the inverted ECC of an erased step */

	erased_page = kmalloc(eccsize, GFP_KERNEL);

	if (!erased_page)

		goto fail;

	if (!erased_page) {

		ret = -ENOMEM;

		goto cleanup;

	}



	memset(erased_page, 0xff, eccsize);

	bch_encode(engine_conf->bch, erased_page, eccsize,
@@ -166,33 +144,262 @@ int nand_ecc_sw_bch_init(struct nand_device *nand) 
	for (i = 0; i < eccbytes; i++)

		engine_conf->eccmask[i] ^= 0xff;



	if (!eccstrength)

		nand->ecc.ctx.conf.strength = (eccbytes * 8) / fls(8 * eccsize);

	/* Verify that the number of code bytes has the expected value */

	if (engine_conf->bch->ecc_bytes != eccbytes) {

		pr_err("Invalid number of ECC bytes: %u, expected: %u\n",

		       eccbytes, engine_conf->bch->ecc_bytes);

		ret = -EINVAL;

		goto cleanup;

	}



	/* Sanity checks */

	if (8 * (eccsize + eccbytes) >= (1 << m)) {

		pr_err("ECC step size is too large (%u)\n", eccsize);

		ret = -EINVAL;

		goto cleanup;

	}



	return 0;



fail:

cleanup:

	nand_ecc_sw_bch_cleanup(nand);



	return ret;

}



int nand_ecc_sw_bch_init_ctx(struct nand_device *nand)

{

	struct nand_ecc_props *conf = &nand->ecc.ctx.conf;

	struct mtd_info *mtd = nanddev_to_mtd(nand);

	struct nand_ecc_sw_bch_conf *engine_conf;

	unsigned int code_size = 0, nsteps;

	int ret;



	/* Only large page NAND chips may use BCH */

	if (mtd->oobsize < 64) {

		pr_err("BCH cannot be used with small page NAND chips\n");

		return -EINVAL;

	}

EXPORT_SYMBOL(nand_ecc_sw_bch_init);



/**

 * nand_ecc_sw_bch_cleanup - Cleanup software BCH ECC resources

 * @nand: NAND device

	if (!mtd->ooblayout)

		mtd_set_ooblayout(mtd, nand_get_large_page_ooblayout());



	conf->engine_type = NAND_ECC_ENGINE_TYPE_SOFT;

	conf->algo = NAND_ECC_ALGO_BCH;

	conf->step_size = nand->ecc.user_conf.step_size;

	conf->strength = nand->ecc.user_conf.strength;



	/*

	 * Board driver should supply ECC size and ECC strength

	 * values to select how many bits are correctable.

	 * Otherwise, default to 512 bytes for large page devices and 256 for

	 * small page devices.

	 */

void nand_ecc_sw_bch_cleanup(struct nand_device *nand)

	if (!conf->step_size) {

		if (mtd->oobsize >= 64)

			conf->step_size = 512;

		else

			conf->step_size = 256;



		conf->strength = 4;

	}



	nsteps = mtd->writesize / conf->step_size;



	/* Maximize */

	if (nand->ecc.user_conf.flags & NAND_ECC_MAXIMIZE_STRENGTH) {

		conf->step_size = 1024;

		nsteps = mtd->writesize / conf->step_size;

		/* Reserve 2 bytes for the BBM */

		code_size = (mtd->oobsize - 2) / nsteps;

		conf->strength = code_size * 8 / fls(8 * conf->step_size);

	}



	if (!code_size)

		code_size = DIV_ROUND_UP(conf->strength *

					 fls(8 * conf->step_size), 8);



	if (!conf->strength)

		conf->strength = (code_size * 8) / fls(8 * conf->step_size);



	if (!code_size && !conf->strength) {

		pr_err("Missing ECC parameters\n");

		return -EINVAL;

	}



	engine_conf = kzalloc(sizeof(*engine_conf), GFP_KERNEL);

	if (!engine_conf)

		return -ENOMEM;



	ret = nand_ecc_init_req_tweaking(&engine_conf->req_ctx, nand);

	if (ret)

		goto free_engine_conf;



	engine_conf->code_size = code_size;

	engine_conf->nsteps = nsteps;

	engine_conf->calc_buf = kzalloc(mtd->oobsize, GFP_KERNEL);

	engine_conf->code_buf = kzalloc(mtd->oobsize, GFP_KERNEL);

	if (!engine_conf->calc_buf || !engine_conf->code_buf) {

		ret = -ENOMEM;

		goto free_bufs;

	}



	nand->ecc.ctx.priv = engine_conf;

	nand->ecc.ctx.total = nsteps * code_size;



	ret = nand_ecc_sw_bch_init(nand);

	if (ret)

		goto free_bufs;



	/* Verify the layout validity */

	if (mtd_ooblayout_count_eccbytes(mtd) !=

	    engine_conf->nsteps * engine_conf->code_size) {

		pr_err("Invalid ECC layout\n");

		ret = -EINVAL;

		goto cleanup_bch_ctx;

	}



	return 0;



cleanup_bch_ctx:

	nand_ecc_sw_bch_cleanup(nand);

free_bufs:

	nand_ecc_cleanup_req_tweaking(&engine_conf->req_ctx);

	kfree(engine_conf->calc_buf);

	kfree(engine_conf->code_buf);

free_engine_conf:

	kfree(engine_conf);



	return ret;

}

EXPORT_SYMBOL(nand_ecc_sw_bch_init_ctx);



void nand_ecc_sw_bch_cleanup_ctx(struct nand_device *nand)

{

	struct nand_ecc_sw_bch_conf *engine_conf = nand->ecc.ctx.priv;



	if (engine_conf) {

		bch_free(engine_conf->bch);

		kfree(engine_conf->errloc);

		kfree(engine_conf->eccmask);

		nand_ecc_sw_bch_cleanup(nand);

		nand_ecc_cleanup_req_tweaking(&engine_conf->req_ctx);

		kfree(engine_conf->calc_buf);

		kfree(engine_conf->code_buf);

		kfree(engine_conf);

	}

}

EXPORT_SYMBOL(nand_ecc_sw_bch_cleanup_ctx);



static int nand_ecc_sw_bch_prepare_io_req(struct nand_device *nand,

					  struct nand_page_io_req *req)

{

	struct nand_ecc_sw_bch_conf *engine_conf = nand->ecc.ctx.priv;

	struct mtd_info *mtd = nanddev_to_mtd(nand);

	int eccsize = nand->ecc.ctx.conf.step_size;

	int eccbytes = engine_conf->code_size;

	int eccsteps = engine_conf->nsteps;

	int total = nand->ecc.ctx.total;

	u8 *ecccalc = engine_conf->calc_buf;

	const u8 *data;

	int i;



	/* Nothing to do for a raw operation */

	if (req->mode == MTD_OPS_RAW)

		return 0;



	/* This engine does not provide BBM/free OOB bytes protection */

	if (!req->datalen)

		return 0;



	nand_ecc_tweak_req(&engine_conf->req_ctx, req);



	/* No more preparation for page read */

	if (req->type == NAND_PAGE_READ)

		return 0;



	/* Preparation for page write: derive the ECC bytes and place them */

	for (i = 0, data = req->databuf.out;

	     eccsteps;

	     eccsteps--, i += eccbytes, data += eccsize)

		nand_ecc_sw_bch_calculate(nand, data, &ecccalc[i]);



	return mtd_ooblayout_set_eccbytes(mtd, ecccalc, (void *)req->oobbuf.out,

					  0, total);

}



static int nand_ecc_sw_bch_finish_io_req(struct nand_device *nand,

					 struct nand_page_io_req *req)

{

	struct nand_ecc_sw_bch_conf *engine_conf = nand->ecc.ctx.priv;

	struct mtd_info *mtd = nanddev_to_mtd(nand);

	int eccsize = nand->ecc.ctx.conf.step_size;

	int total = nand->ecc.ctx.total;

	int eccbytes = engine_conf->code_size;

	int eccsteps = engine_conf->nsteps;

	u8 *ecccalc = engine_conf->calc_buf;

	u8 *ecccode = engine_conf->code_buf;

	unsigned int max_bitflips = 0;

	u8 *data = req->databuf.in;

	int i, ret;



	/* Nothing to do for a raw operation */

	if (req->mode == MTD_OPS_RAW)

		return 0;



	/* This engine does not provide BBM/free OOB bytes protection */

	if (!req->datalen)

		return 0;



	/* No more preparation for page write */

	if (req->type == NAND_PAGE_WRITE) {

		nand_ecc_restore_req(&engine_conf->req_ctx, req);

		return 0;

	}



	/* Finish a page read: retrieve the (raw) ECC bytes*/

	ret = mtd_ooblayout_get_eccbytes(mtd, ecccode, req->oobbuf.in, 0,

					 total);

	if (ret)

		return ret;



	/* Calculate the ECC bytes */

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, data += eccsize)

		nand_ecc_sw_bch_calculate(nand, data, &ecccalc[i]);



	/* Finish a page read: compare and correct */

	for (eccsteps = engine_conf->nsteps, i = 0, data = req->databuf.in;

	     eccsteps;

	     eccsteps--, i += eccbytes, data += eccsize) {

		int stat =  nand_ecc_sw_bch_correct(nand, data,

						    &ecccode[i],

						    &ecccalc[i]);

		if (stat < 0) {

			mtd->ecc_stats.failed++;

		} else {

			mtd->ecc_stats.corrected += stat;

			max_bitflips = max_t(unsigned int, max_bitflips, stat);

		}

	}



	nand_ecc_restore_req(&engine_conf->req_ctx, req);



	return max_bitflips;

}



static struct nand_ecc_engine_ops nand_ecc_sw_bch_engine_ops = {

	.init_ctx = nand_ecc_sw_bch_init_ctx,

	.cleanup_ctx = nand_ecc_sw_bch_cleanup_ctx,

	.prepare_io_req = nand_ecc_sw_bch_prepare_io_req,

	.finish_io_req = nand_ecc_sw_bch_finish_io_req,

};



static struct nand_ecc_engine nand_ecc_sw_bch_engine = {

	.ops = &nand_ecc_sw_bch_engine_ops,

};



struct nand_ecc_engine *nand_ecc_sw_bch_get_engine(void)

{

	return &nand_ecc_sw_bch_engine;

}

EXPORT_SYMBOL(nand_ecc_sw_bch_cleanup);

EXPORT_SYMBOL(nand_ecc_sw_bch_get_engine);



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Ivan Djelic <ivan.djelic@parrot.com>");

drivers/mtd/nand/raw/nand_base.c

+9 −53
Original line number Diff line number Diff line
@@ -5150,17 +5150,11 @@ int rawnand_sw_bch_init(struct nand_chip *chip) 
	base->ecc.user_conf.step_size = chip->ecc.size;

	base->ecc.user_conf.strength = chip->ecc.strength;



	engine_conf = kzalloc(sizeof(*engine_conf), GFP_KERNEL);

	if (!engine_conf)

		return -ENOMEM;



	engine_conf->code_size = chip->ecc.bytes;



	base->ecc.ctx.priv = engine_conf;



	ret = nand_ecc_sw_bch_init(base);

	ret = nand_ecc_sw_bch_init_ctx(base);

	if (ret)

		kfree(base->ecc.ctx.priv);

		return ret;



	engine_conf = base->ecc.ctx.priv;



	chip->ecc.size = base->ecc.ctx.conf.step_size;

	chip->ecc.strength = base->ecc.ctx.conf.strength;
@@ -5168,7 +5162,7 @@ int rawnand_sw_bch_init(struct nand_chip *chip) 
	chip->ecc.steps = engine_conf->nsteps;

	chip->ecc.bytes = engine_conf->code_size;



	return ret;

	return 0;

}

EXPORT_SYMBOL(rawnand_sw_bch_init);
@@ -5194,9 +5188,7 @@ void rawnand_sw_bch_cleanup(struct nand_chip *chip) 
{

	struct nand_device *base = &chip->base;



	nand_ecc_sw_bch_cleanup(base);



	kfree(base->ecc.ctx.priv);

	nand_ecc_sw_bch_cleanup_ctx(base);

}

EXPORT_SYMBOL(rawnand_sw_bch_cleanup);
@@ -5308,51 +5300,15 @@ static int nand_set_ecc_soft_ops(struct nand_chip *chip) 
		ecc->read_oob = nand_read_oob_std;

		ecc->write_oob = nand_write_oob_std;



		/*

		* Board driver should supply ecc.size and ecc.strength

		* values to select how many bits are correctable.

		* Otherwise, default to 4 bits for large page devices.

		*/

		if (!ecc->size && (mtd->oobsize >= 64)) {

			ecc->size = 512;

			ecc->strength = 4;

		}



		/*

		 * if no ecc placement scheme was provided pickup the default

		 * large page one.

		 */

		if (!mtd->ooblayout) {

			/* handle large page devices only */

			if (mtd->oobsize < 64) {

				WARN(1, "OOB layout is required when using software BCH on small pages\n");

				return -EINVAL;

			}



			mtd_set_ooblayout(mtd, nand_get_large_page_ooblayout());



		}



		/*

		 * We can only maximize ECC config when the default layout is

		 * used, otherwise we don't know how many bytes can really be

		 * used.

		 */

		if (mtd->ooblayout == nand_get_large_page_ooblayout() &&

		    nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE_STRENGTH) {

			int steps, bytes;



			/* Always prefer 1k blocks over 512bytes ones */

			ecc->size = 1024;

			steps = mtd->writesize / ecc->size;

		if (nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE_STRENGTH &&

		    mtd->ooblayout != nand_get_large_page_ooblayout())

			nanddev->ecc.user_conf.flags &= ~NAND_ECC_MAXIMIZE_STRENGTH;



			/* Reserve 2 bytes for the BBM */

			bytes = (mtd->oobsize - 2) / steps;

			ecc->strength = bytes * 8 / fls(8 * ecc->size);

		}



		/* See the software BCH ECC initialization for details */

		ecc->bytes = 0;

		ret = rawnand_sw_bch_init(chip);

		if (ret) {

			WARN(1, "BCH ECC initialization failed!\n");

include/linux/mtd/nand-ecc-sw-bch.h

+8 −8
Original line number Diff line number Diff line
@@ -13,8 +13,8 @@ 


/**

 * struct nand_ecc_sw_bch_conf - private software BCH ECC engine structure

 * @reqooblen: Save the actual user OOB length requested before overwriting it

 * @spare_oobbuf: Spare OOB buffer if none is provided

 * @req_ctx: Save request context and tweak the original request to fit the

 *           engine needs

 * @code_size: Number of bytes needed to store a code (one code per step)

 * @nsteps: Number of steps

 * @calc_buf: Buffer to use when calculating ECC bytes
@@ -24,8 +24,7 @@ 
 * @eccmask: XOR ecc mask, allows erased pages to be decoded as valid

 */

struct nand_ecc_sw_bch_conf {

	unsigned int reqooblen;

	void *spare_oobbuf;

	struct nand_ecc_req_tweak_ctx req_ctx;

	unsigned int code_size;

	unsigned int nsteps;

	u8 *calc_buf;
@@ -41,8 +40,9 @@ int nand_ecc_sw_bch_calculate(struct nand_device *nand, 
			      const unsigned char *buf, unsigned char *code);

int nand_ecc_sw_bch_correct(struct nand_device *nand, unsigned char *buf,

			    unsigned char *read_ecc, unsigned char *calc_ecc);

int nand_ecc_sw_bch_init(struct nand_device *nand);

void nand_ecc_sw_bch_cleanup(struct nand_device *nand);

int nand_ecc_sw_bch_init_ctx(struct nand_device *nand);

void nand_ecc_sw_bch_cleanup_ctx(struct nand_device *nand);

struct nand_ecc_engine *nand_ecc_sw_bch_get_engine(void);



#else /* !CONFIG_MTD_NAND_ECC_SW_BCH */
@@ -61,12 +61,12 @@ static inline int nand_ecc_sw_bch_correct(struct nand_device *nand, 
	return -ENOTSUPP;

}



static inline int nand_ecc_sw_bch_init(struct nand_device *nand)

static inline int nand_ecc_sw_bch_init_ctx(struct nand_device *nand)

{

	return -ENOTSUPP;

}



static inline void nand_ecc_sw_bch_cleanup(struct nand_device *nand) {}

static inline void nand_ecc_sw_bch_cleanup_ctx(struct nand_device *nand) {}



#endif /* CONFIG_MTD_NAND_ECC_SW_BCH */

include/linux/mtd/nand.h

+9 −0
Original line number Diff line number Diff line
@@ -278,6 +278,15 @@ int nand_ecc_finish_io_req(struct nand_device *nand, 
			   struct nand_page_io_req *req);

bool nand_ecc_is_strong_enough(struct nand_device *nand);



#if IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_BCH)

struct nand_ecc_engine *nand_ecc_sw_bch_get_engine(void);

#else

static inline struct nand_ecc_engine *nand_ecc_sw_bch_get_engine(void)

{

	return NULL;

}

#endif /* CONFIG_MTD_NAND_ECC_SW_BCH */



/**

 * struct nand_ecc_req_tweak_ctx - Help for automatically tweaking requests

 * @orig_req: Pointer to the original IO request