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Commit 75eb2cec authored Feb 04, 2016 by Boris Brezillon

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: Boris 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)
		{