Commit 75eb2cec authored by Boris Brezillon's avatar Boris Brezillon
Browse files

mtd: add mtd_ooblayout_xxx() helper functions 



In order to make the ecclayout definition completely dynamic we need to
rework the way the OOB layout are defined and iterated.

Create a few mtd_ooblayout_xxx() helpers to ease OOB bytes manipulation
and hide ecclayout internals to their users.

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
parent c4f3ef2c

drivers/mtd/mtdcore.c

+400 −0
Original line number Diff line number Diff line
@@ -1016,6 +1016,406 @@ int mtd_write_oob(struct mtd_info *mtd, loff_t to, 
}

EXPORT_SYMBOL_GPL(mtd_write_oob);



/**

 * mtd_ooblayout_ecc - Get the OOB region definition of a specific ECC section

 * @mtd: MTD device structure

 * @section: ECC section. Depending on the layout you may have all the ECC

 *	     bytes stored in a single contiguous section, or one section

 *	     per ECC chunk (and sometime several sections for a single ECC

 *	     ECC chunk)

 * @oobecc: OOB region struct filled with the appropriate ECC position

 *	    information

 *

 * This functions return ECC section information in the OOB area. I you want

 * to get all the ECC bytes information, then you should call

 * mtd_ooblayout_ecc(mtd, section++, oobecc) until it returns -ERANGE.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,

		      struct mtd_oob_region *oobecc)

{

	int eccbyte = 0, cursection = 0, length = 0, eccpos = 0;



	memset(oobecc, 0, sizeof(*oobecc));



	if (!mtd || section < 0)

		return -EINVAL;



	if (!mtd->ecclayout)

		return -ENOTSUPP;



	/*

	 * This logic allows us to reuse the ->ecclayout information and

	 * expose them as ECC regions (as done for the OOB free regions).

	 *

	 * TODO: this should be dropped as soon as we get rid of the

	 * ->ecclayout field.

	 */

	for (eccbyte = 0; eccbyte < mtd->ecclayout->eccbytes; eccbyte++) {

		eccpos = mtd->ecclayout->eccpos[eccbyte];



		if (eccbyte < mtd->ecclayout->eccbytes - 1) {

			int neccpos = mtd->ecclayout->eccpos[eccbyte + 1];



			if (eccpos + 1 == neccpos) {

				length++;

				continue;

			}

		}



		if (section == cursection)

			break;



		length = 0;

		cursection++;

	}



	if (cursection != section || eccbyte >= mtd->ecclayout->eccbytes)

		return -ERANGE;



	oobecc->length = length + 1;

	oobecc->offset = eccpos - length;



	return 0;

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_ecc);



/**

 * mtd_ooblayout_free - Get the OOB region definition of a specific free

 *			section

 * @mtd: MTD device structure

 * @section: Free section you are interested in. Depending on the layout

 *	     you may have all the free bytes stored in a single contiguous

 *	     section, or one section per ECC chunk plus an extra section

 *	     for the remaining bytes (or other funky layout).

 * @oobfree: OOB region struct filled with the appropriate free position

 *	     information

 *

 * This functions return free bytes position in the OOB area. I you want

 * to get all the free bytes information, then you should call

 * mtd_ooblayout_free(mtd, section++, oobfree) until it returns -ERANGE.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_free(struct mtd_info *mtd, int section,

		       struct mtd_oob_region *oobfree)

{

	memset(oobfree, 0, sizeof(*oobfree));



	if (!mtd || section < 0)

		return -EINVAL;



	if (!mtd->ecclayout)

		return -ENOTSUPP;



	if (section >= MTD_MAX_OOBFREE_ENTRIES_LARGE)

		return -ERANGE;



	oobfree->offset = mtd->ecclayout->oobfree[section].offset;

	oobfree->length = mtd->ecclayout->oobfree[section].length;



	return 0;

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_free);



/**

 * mtd_ooblayout_find_region - Find the region attached to a specific byte

 * @mtd: mtd info structure

 * @byte: the byte we are searching for

 * @sectionp: pointer where the section id will be stored

 * @oobregion: used to retrieve the ECC position

 * @iter: iterator function. Should be either mtd_ooblayout_free or

 *	  mtd_ooblayout_ecc depending on the region type you're searching for

 *

 * This functions returns the section id and oobregion information of a

 * specific byte. For example, say you want to know where the 4th ECC byte is

 * stored, you'll use:

 *

 * mtd_ooblayout_find_region(mtd, 3, &section, &oobregion, mtd_ooblayout_ecc);

 *

 * Returns zero on success, a negative error code otherwise.

 */

static int mtd_ooblayout_find_region(struct mtd_info *mtd, int byte,

				int *sectionp, struct mtd_oob_region *oobregion,

				int (*iter)(struct mtd_info *,

					    int section,

					    struct mtd_oob_region *oobregion))

{

	int pos = 0, ret, section = 0;



	memset(oobregion, 0, sizeof(*oobregion));



	while (1) {

		ret = iter(mtd, section, oobregion);

		if (ret)

			return ret;



		if (pos + oobregion->length > byte)

			break;



		pos += oobregion->length;

		section++;

	}



	/*

	 * Adjust region info to make it start at the beginning at the

	 * 'start' ECC byte.

	 */

	oobregion->offset += byte - pos;

	oobregion->length -= byte - pos;

	*sectionp = section;



	return 0;

}



/**

 * mtd_ooblayout_find_eccregion - Find the ECC region attached to a specific

 *				  ECC byte

 * @mtd: mtd info structure

 * @eccbyte: the byte we are searching for

 * @sectionp: pointer where the section id will be stored

 * @oobregion: OOB region information

 *

 * Works like mtd_ooblayout_find_region() except it searches for a specific ECC

 * byte.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_find_eccregion(struct mtd_info *mtd, int eccbyte,

				 int *section,

				 struct mtd_oob_region *oobregion)

{

	return mtd_ooblayout_find_region(mtd, eccbyte, section, oobregion,

					 mtd_ooblayout_ecc);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_find_eccregion);



/**

 * mtd_ooblayout_get_bytes - Extract OOB bytes from the oob buffer

 * @mtd: mtd info structure

 * @buf: destination buffer to store OOB bytes

 * @oobbuf: OOB buffer

 * @start: first byte to retrieve

 * @nbytes: number of bytes to retrieve

 * @iter: section iterator

 *

 * Extract bytes attached to a specific category (ECC or free)

 * from the OOB buffer and copy them into buf.

 *

 * Returns zero on success, a negative error code otherwise.

 */

static int mtd_ooblayout_get_bytes(struct mtd_info *mtd, u8 *buf,

				const u8 *oobbuf, int start, int nbytes,

				int (*iter)(struct mtd_info *,

					    int section,

					    struct mtd_oob_region *oobregion))

{

	struct mtd_oob_region oobregion = { };

	int section = 0, ret;



	ret = mtd_ooblayout_find_region(mtd, start, &section,

					&oobregion, iter);



	while (!ret) {

		int cnt;



		cnt = oobregion.length > nbytes ? nbytes : oobregion.length;

		memcpy(buf, oobbuf + oobregion.offset, cnt);

		buf += cnt;

		nbytes -= cnt;



		if (!nbytes)

			break;



		ret = iter(mtd, ++section, &oobregion);

	}



	return ret;

}



/**

 * mtd_ooblayout_set_bytes - put OOB bytes into the oob buffer

 * @mtd: mtd info structure

 * @buf: source buffer to get OOB bytes from

 * @oobbuf: OOB buffer

 * @start: first OOB byte to set

 * @nbytes: number of OOB bytes to set

 * @iter: section iterator

 *

 * Fill the OOB buffer with data provided in buf. The category (ECC or free)

 * is selected by passing the appropriate iterator.

 *

 * Returns zero on success, a negative error code otherwise.

 */

static int mtd_ooblayout_set_bytes(struct mtd_info *mtd, const u8 *buf,

				u8 *oobbuf, int start, int nbytes,

				int (*iter)(struct mtd_info *,

					    int section,

					    struct mtd_oob_region *oobregion))

{

	struct mtd_oob_region oobregion = { };

	int section = 0, ret;



	ret = mtd_ooblayout_find_region(mtd, start, &section,

					&oobregion, iter);



	while (!ret) {

		int cnt;



		cnt = oobregion.length > nbytes ? nbytes : oobregion.length;

		memcpy(oobbuf + oobregion.offset, buf, cnt);

		buf += cnt;

		nbytes -= cnt;



		if (!nbytes)

			break;



		ret = iter(mtd, ++section, &oobregion);

	}



	return ret;

}



/**

 * mtd_ooblayout_count_bytes - count the number of bytes in a OOB category

 * @mtd: mtd info structure

 * @iter: category iterator

 *

 * Count the number of bytes in a given category.

 *

 * Returns a positive value on success, a negative error code otherwise.

 */

static int mtd_ooblayout_count_bytes(struct mtd_info *mtd,

				int (*iter)(struct mtd_info *,

					    int section,

					    struct mtd_oob_region *oobregion))

{

	struct mtd_oob_region oobregion = { };

	int section = 0, ret, nbytes = 0;



	while (1) {

		ret = iter(mtd, section++, &oobregion);

		if (ret) {

			if (ret == -ERANGE)

				ret = nbytes;

			break;

		}



		nbytes += oobregion.length;

	}



	return ret;

}



/**

 * mtd_ooblayout_get_eccbytes - extract ECC bytes from the oob buffer

 * @mtd: mtd info structure

 * @eccbuf: destination buffer to store ECC bytes

 * @oobbuf: OOB buffer

 * @start: first ECC byte to retrieve

 * @nbytes: number of ECC bytes to retrieve

 *

 * Works like mtd_ooblayout_get_bytes(), except it acts on ECC bytes.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_get_eccbytes(struct mtd_info *mtd, u8 *eccbuf,

			       const u8 *oobbuf, int start, int nbytes)

{

	return mtd_ooblayout_get_bytes(mtd, eccbuf, oobbuf, start, nbytes,

				       mtd_ooblayout_ecc);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_get_eccbytes);



/**

 * mtd_ooblayout_set_eccbytes - set ECC bytes into the oob buffer

 * @mtd: mtd info structure

 * @eccbuf: source buffer to get ECC bytes from

 * @oobbuf: OOB buffer

 * @start: first ECC byte to set

 * @nbytes: number of ECC bytes to set

 *

 * Works like mtd_ooblayout_set_bytes(), except it acts on ECC bytes.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_set_eccbytes(struct mtd_info *mtd, const u8 *eccbuf,

			       u8 *oobbuf, int start, int nbytes)

{

	return mtd_ooblayout_set_bytes(mtd, eccbuf, oobbuf, start, nbytes,

				       mtd_ooblayout_ecc);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_set_eccbytes);



/**

 * mtd_ooblayout_get_databytes - extract data bytes from the oob buffer

 * @mtd: mtd info structure

 * @databuf: destination buffer to store ECC bytes

 * @oobbuf: OOB buffer

 * @start: first ECC byte to retrieve

 * @nbytes: number of ECC bytes to retrieve

 *

 * Works like mtd_ooblayout_get_bytes(), except it acts on free bytes.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_get_databytes(struct mtd_info *mtd, u8 *databuf,

				const u8 *oobbuf, int start, int nbytes)

{

	return mtd_ooblayout_get_bytes(mtd, databuf, oobbuf, start, nbytes,

				       mtd_ooblayout_free);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_get_databytes);



/**

 * mtd_ooblayout_get_eccbytes - set data bytes into the oob buffer

 * @mtd: mtd info structure

 * @eccbuf: source buffer to get data bytes from

 * @oobbuf: OOB buffer

 * @start: first ECC byte to set

 * @nbytes: number of ECC bytes to set

 *

 * Works like mtd_ooblayout_get_bytes(), except it acts on free bytes.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_set_databytes(struct mtd_info *mtd, const u8 *databuf,

				u8 *oobbuf, int start, int nbytes)

{

	return mtd_ooblayout_set_bytes(mtd, databuf, oobbuf, start, nbytes,

				       mtd_ooblayout_free);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_set_databytes);



/**

 * mtd_ooblayout_count_freebytes - count the number of free bytes in OOB

 * @mtd: mtd info structure

 *

 * Works like mtd_ooblayout_count_bytes(), except it count free bytes.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_count_freebytes(struct mtd_info *mtd)

{

	return mtd_ooblayout_count_bytes(mtd, mtd_ooblayout_free);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_count_freebytes);



/**

 * mtd_ooblayout_count_freebytes - count the number of ECC bytes in OOB

 * @mtd: mtd info structure

 *

 * Works like mtd_ooblayout_count_bytes(), except it count ECC bytes.

 *

 * Returns zero on success, a negative error code otherwise.

 */

int mtd_ooblayout_count_eccbytes(struct mtd_info *mtd)

{

	return mtd_ooblayout_count_bytes(mtd, mtd_ooblayout_ecc);

}

EXPORT_SYMBOL_GPL(mtd_ooblayout_count_eccbytes);



/*

 * Method to access the protection register area, present in some flash

 * devices. The user data is one time programmable but the factory data is read

include/linux/mtd/mtd.h

+33 −0
Original line number Diff line number Diff line
@@ -108,6 +108,21 @@ struct nand_ecclayout { 
	struct nand_oobfree oobfree[MTD_MAX_OOBFREE_ENTRIES_LARGE];

};



/**

 * struct mtd_oob_region - oob region definition

 * @offset: region offset

 * @length: region length

 *

 * This structure describes a region of the OOB area, and is used

 * to retrieve ECC or free bytes sections.

 * Each section is defined by an offset within the OOB area and a

 * length.

 */

struct mtd_oob_region {

	u32 offset;

	u32 length;

};



struct module;	/* only needed for owner field in mtd_info */



struct mtd_info {
@@ -253,6 +268,24 @@ struct mtd_info { 
	int usecount;

};



int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,

		      struct mtd_oob_region *oobecc);

int mtd_ooblayout_find_eccregion(struct mtd_info *mtd, int eccbyte,

				 int *section,

				 struct mtd_oob_region *oobregion);

int mtd_ooblayout_get_eccbytes(struct mtd_info *mtd, u8 *eccbuf,

			       const u8 *oobbuf, int start, int nbytes);

int mtd_ooblayout_set_eccbytes(struct mtd_info *mtd, const u8 *eccbuf,

			       u8 *oobbuf, int start, int nbytes);

int mtd_ooblayout_free(struct mtd_info *mtd, int section,

		       struct mtd_oob_region *oobfree);

int mtd_ooblayout_get_databytes(struct mtd_info *mtd, u8 *databuf,

				const u8 *oobbuf, int start, int nbytes);

int mtd_ooblayout_set_databytes(struct mtd_info *mtd, const u8 *databuf,

				u8 *oobbuf, int start, int nbytes);

int mtd_ooblayout_count_freebytes(struct mtd_info *mtd);

int mtd_ooblayout_count_eccbytes(struct mtd_info *mtd);



static inline void mtd_set_of_node(struct mtd_info *mtd,

				   struct device_node *np)

{

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