diff options
| -rw-r--r-- | drivers/mtd/mtdcore.c | 104 | ||||
| -rw-r--r-- | drivers/mtd/mtdpart.c | 1 | ||||
| -rw-r--r-- | include/linux/mtd/mtd.h | 107 |
3 files changed, 212 insertions, 0 deletions
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index e3936b847c6b..4f270482cfd0 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -376,6 +376,110 @@ static int mtd_reboot_notifier(struct notifier_block *n, unsigned long state, } /** + * mtd_wunit_to_pairing_info - get pairing information of a wunit + * @mtd: pointer to new MTD device info structure + * @wunit: write unit we are interested in + * @info: returned pairing information + * + * Retrieve pairing information associated to the wunit. + * This is mainly useful when dealing with MLC/TLC NANDs where pages can be + * paired together, and where programming a page may influence the page it is + * paired with. + * The notion of page is replaced by the term wunit (write-unit) to stay + * consistent with the ->writesize field. + * + * The @wunit argument can be extracted from an absolute offset using + * mtd_offset_to_wunit(). @info is filled with the pairing information attached + * to @wunit. + * + * From the pairing info the MTD user can find all the wunits paired with + * @wunit using the following loop: + * + * for (i = 0; i < mtd_pairing_groups(mtd); i++) { + * info.pair = i; + * mtd_pairing_info_to_wunit(mtd, &info); + * ... + * } + */ +int mtd_wunit_to_pairing_info(struct mtd_info *mtd, int wunit, + struct mtd_pairing_info *info) +{ + int npairs = mtd_wunit_per_eb(mtd) / mtd_pairing_groups(mtd); + + if (wunit < 0 || wunit >= npairs) + return -EINVAL; + + if (mtd->pairing && mtd->pairing->get_info) + return mtd->pairing->get_info(mtd, wunit, info); + + info->group = 0; + info->pair = wunit; + + return 0; +} +EXPORT_SYMBOL_GPL(mtd_wunit_to_pairing_info); + +/** + * mtd_wunit_to_pairing_info - get wunit from pairing information + * @mtd: pointer to new MTD device info structure + * @info: pairing information struct + * + * Returns a positive number representing the wunit associated to the info + * struct, or a negative error code. + * + * This is the reverse of mtd_wunit_to_pairing_info(), and can help one to + * iterate over all wunits of a given pair (see mtd_wunit_to_pairing_info() + * doc). + * + * It can also be used to only program the first page of each pair (i.e. + * page attached to group 0), which allows one to use an MLC NAND in + * software-emulated SLC mode: + * + * info.group = 0; + * npairs = mtd_wunit_per_eb(mtd) / mtd_pairing_groups(mtd); + * for (info.pair = 0; info.pair < npairs; info.pair++) { + * wunit = mtd_pairing_info_to_wunit(mtd, &info); + * mtd_write(mtd, mtd_wunit_to_offset(mtd, blkoffs, wunit), + * mtd->writesize, &retlen, buf + (i * mtd->writesize)); + * } + */ +int mtd_pairing_info_to_wunit(struct mtd_info *mtd, + const struct mtd_pairing_info *info) +{ + int ngroups = mtd_pairing_groups(mtd); + int npairs = mtd_wunit_per_eb(mtd) / ngroups; + + if (!info || info->pair < 0 || info->pair >= npairs || + info->group < 0 || info->group >= ngroups) + return -EINVAL; + + if (mtd->pairing && mtd->pairing->get_wunit) + return mtd->pairing->get_wunit(mtd, info); + + return info->pair; +} +EXPORT_SYMBOL_GPL(mtd_pairing_info_to_wunit); + +/** + * mtd_pairing_groups - get the number of pairing groups + * @mtd: pointer to new MTD device info structure + * + * Returns the number of pairing groups. + * + * This number is usually equal to the number of bits exposed by a single + * cell, and can be used in conjunction with mtd_pairing_info_to_wunit() + * to iterate over all pages of a given pair. + */ +int mtd_pairing_groups(struct mtd_info *mtd) +{ + if (!mtd->pairing || !mtd->pairing->ngroups) + return 1; + + return mtd->pairing->ngroups; +} +EXPORT_SYMBOL_GPL(mtd_pairing_groups); + +/** * add_mtd_device - register an MTD device * @mtd: pointer to new MTD device info structure * diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c index 1f13e32556f8..e32a0ac2298f 100644 --- a/drivers/mtd/mtdpart.c +++ b/drivers/mtd/mtdpart.c @@ -397,6 +397,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *master, slave->mtd.oobsize = master->oobsize; slave->mtd.oobavail = master->oobavail; slave->mtd.subpage_sft = master->subpage_sft; + slave->mtd.pairing = master->pairing; slave->mtd.name = name; slave->mtd.owner = master->owner; diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index 29a170612203..13f8052b9ff9 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -127,6 +127,82 @@ struct mtd_ooblayout_ops { struct mtd_oob_region *oobfree); }; +/** + * struct mtd_pairing_info - page pairing information + * + * @pair: pair id + * @group: group id + * + * The term "pair" is used here, even though TLC NANDs might group pages by 3 + * (3 bits in a single cell). A pair should regroup all pages that are sharing + * the same cell. Pairs are then indexed in ascending order. + * + * @group is defining the position of a page in a given pair. It can also be + * seen as the bit position in the cell: page attached to bit 0 belongs to + * group 0, page attached to bit 1 belongs to group 1, etc. + * + * Example: + * The H27UCG8T2BTR-BC datasheet describes the following pairing scheme: + * + * group-0 group-1 + * + * pair-0 page-0 page-4 + * pair-1 page-1 page-5 + * pair-2 page-2 page-8 + * ... + * pair-127 page-251 page-255 + * + * + * Note that the "group" and "pair" terms were extracted from Samsung and + * Hynix datasheets, and might be referenced under other names in other + * datasheets (Micron is describing this concept as "shared pages"). + */ +struct mtd_pairing_info { + int pair; + int group; +}; + +/** + * struct mtd_pairing_scheme - page pairing scheme description + * + * @ngroups: number of groups. Should be related to the number of bits + * per cell. + * @get_info: converts a write-unit (page number within an erase block) into + * mtd_pairing information (pair + group). This function should + * fill the info parameter based on the wunit index or return + * -EINVAL if the wunit parameter is invalid. + * @get_wunit: converts pairing information into a write-unit (page) number. + * This function should return the wunit index pointed by the + * pairing information described in the info argument. It should + * return -EINVAL, if there's no wunit corresponding to the + * passed pairing information. + * + * See mtd_pairing_info documentation for a detailed explanation of the + * pair and group concepts. + * + * The mtd_pairing_scheme structure provides a generic solution to represent + * NAND page pairing scheme. Instead of exposing two big tables to do the + * write-unit <-> (pair + group) conversions, we ask the MTD drivers to + * implement the ->get_info() and ->get_wunit() functions. + * + * MTD users will then be able to query these information by using the + * mtd_pairing_info_to_wunit() and mtd_wunit_to_pairing_info() helpers. + * + * @ngroups is here to help MTD users iterating over all the pages in a + * given pair. This value can be retrieved by MTD users using the + * mtd_pairing_groups() helper. + * + * Examples are given in the mtd_pairing_info_to_wunit() and + * mtd_wunit_to_pairing_info() documentation. + */ +struct mtd_pairing_scheme { + int ngroups; + int (*get_info)(struct mtd_info *mtd, int wunit, + struct mtd_pairing_info *info); + int (*get_wunit)(struct mtd_info *mtd, + const struct mtd_pairing_info *info); +}; + struct module; /* only needed for owner field in mtd_info */ struct mtd_info { @@ -188,6 +264,9 @@ struct mtd_info { /* OOB layout description */ const struct mtd_ooblayout_ops *ooblayout; + /* NAND pairing scheme, only provided for MLC/TLC NANDs */ + const struct mtd_pairing_scheme *pairing; + /* the ecc step size. */ unsigned int ecc_step_size; @@ -296,6 +375,12 @@ static inline void mtd_set_ooblayout(struct mtd_info *mtd, mtd->ooblayout = ooblayout; } +static inline void mtd_set_pairing_scheme(struct mtd_info *mtd, + const struct mtd_pairing_scheme *pairing) +{ + mtd->pairing = pairing; +} + static inline void mtd_set_of_node(struct mtd_info *mtd, struct device_node *np) { @@ -312,6 +397,11 @@ static inline int mtd_oobavail(struct mtd_info *mtd, struct mtd_oob_ops *ops) return ops->mode == MTD_OPS_AUTO_OOB ? mtd->oobavail : mtd->oobsize; } +int mtd_wunit_to_pairing_info(struct mtd_info *mtd, int wunit, + struct mtd_pairing_info *info); +int mtd_pairing_info_to_wunit(struct mtd_info *mtd, + const struct mtd_pairing_info *info); +int mtd_pairing_groups(struct mtd_info *mtd); int mtd_erase(struct mtd_info *mtd, struct erase_info *instr); int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, void **virt, resource_size_t *phys); @@ -397,6 +487,23 @@ static inline uint32_t mtd_mod_by_ws(uint64_t sz, struct mtd_info *mtd) return do_div(sz, mtd->writesize); } +static inline int mtd_wunit_per_eb(struct mtd_info *mtd) +{ + return mtd->erasesize / mtd->writesize; +} + +static inline int mtd_offset_to_wunit(struct mtd_info *mtd, loff_t offs) +{ + return mtd_div_by_ws(mtd_mod_by_eb(offs, mtd), mtd); +} + +static inline loff_t mtd_wunit_to_offset(struct mtd_info *mtd, loff_t base, + int wunit) +{ + return base + (wunit * mtd->writesize); +} + + static inline int mtd_has_oob(const struct mtd_info *mtd) { return mtd->_read_oob && mtd->_write_oob; |