Introduction of the MTD pairing scheme concept.
-----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAABAgAGBQJX2rbJAAoJEGXtNgF+CLcAnGMP/06Eydb50SiBv7YQRVJTF8Rk K0lPQOJBXX+32xXJYKAj0UIRNsd5yxdH1tmWJFOxUV4etI1K9CtlCMLYoLgqPrPf SVXMBtfZvWmK8D5Mee9BroQIlSOQnzbYO3zAFY8pV8SFZ8y9SMXvPM6Z/2tTlMvK uds1x0t1DHGXLcAwZo4Ctvtxy+x4wS1RmfdMQhWYGSlbAqDzbjwK3Dceq6JmzJ1i UxoYHqXdjAF6h67twADHre5vMwdDgYEgEHZHomXtWpHFslWYpWCQUWLLSnWG3h4d ia3Q2xTFPxKg90PKurGrLffwfo0KnpwieqLYqHZ70d9pgepgqv2N547kPeYPNKIS VdbDqakY7V4P6OZ+ykUJ3VcfDPRXh0b0+V9AVyGPIXH4m03YXlGsKigN1tYHid/K I3DeZqcCX35/Fc4iSD9k+HYlIplx6Ijo3JgpnRVlircczloKk+00mZ2THV5/pYcn vfgxgjeKaTKeG+zcSehfmYFZO1SuvhSFO4/qXLgYd8LWav8QWADQ8H3C2nn/ZlMk krb9S0iAQE9nmAY1ZPUz0hreaaYCEZVst/KAJWAkGW0Laj29gW6PAj/lQb+fG5d4 4aSn4qnPrXQ7P76NAihbtzYGCTFwtlhoBXDXhv3A5aoqI5QaMI6QQ+LkYJMRAn0s HY4ExJEeC/lUe5QiF0Q7 =GnV0 -----END PGP SIGNATURE----- Merge tag '4.9/mtd-pairing-scheme' of github.com:linux-nand/linux Introduction of the MTD pairing scheme concept.hifive-unleashed-5.1
Brian Norris
commit
69db4aa44f
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@ -375,6 +375,110 @@ static int mtd_reboot_notifier(struct notifier_block *n, unsigned long state,
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return NOTIFY_DONE;
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}
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/**
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* mtd_wunit_to_pairing_info - get pairing information of a wunit
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* @mtd: pointer to new MTD device info structure
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* @wunit: write unit we are interested in
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* @info: returned pairing information
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*
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* Retrieve pairing information associated to the wunit.
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* This is mainly useful when dealing with MLC/TLC NANDs where pages can be
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* paired together, and where programming a page may influence the page it is
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* paired with.
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* The notion of page is replaced by the term wunit (write-unit) to stay
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* consistent with the ->writesize field.
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*
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* The @wunit argument can be extracted from an absolute offset using
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* mtd_offset_to_wunit(). @info is filled with the pairing information attached
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* to @wunit.
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*
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* From the pairing info the MTD user can find all the wunits paired with
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* @wunit using the following loop:
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*
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* for (i = 0; i < mtd_pairing_groups(mtd); i++) {
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* info.pair = i;
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* mtd_pairing_info_to_wunit(mtd, &info);
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* ...
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* }
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*/
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int mtd_wunit_to_pairing_info(struct mtd_info *mtd, int wunit,
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struct mtd_pairing_info *info)
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{
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int npairs = mtd_wunit_per_eb(mtd) / mtd_pairing_groups(mtd);
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if (wunit < 0 || wunit >= npairs)
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return -EINVAL;
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if (mtd->pairing && mtd->pairing->get_info)
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return mtd->pairing->get_info(mtd, wunit, info);
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info->group = 0;
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info->pair = wunit;
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return 0;
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}
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EXPORT_SYMBOL_GPL(mtd_wunit_to_pairing_info);
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/**
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* mtd_wunit_to_pairing_info - get wunit from pairing information
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* @mtd: pointer to new MTD device info structure
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* @info: pairing information struct
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*
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* Returns a positive number representing the wunit associated to the info
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* struct, or a negative error code.
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*
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* This is the reverse of mtd_wunit_to_pairing_info(), and can help one to
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* iterate over all wunits of a given pair (see mtd_wunit_to_pairing_info()
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* doc).
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*
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* It can also be used to only program the first page of each pair (i.e.
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* page attached to group 0), which allows one to use an MLC NAND in
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* software-emulated SLC mode:
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*
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* info.group = 0;
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* npairs = mtd_wunit_per_eb(mtd) / mtd_pairing_groups(mtd);
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* for (info.pair = 0; info.pair < npairs; info.pair++) {
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* wunit = mtd_pairing_info_to_wunit(mtd, &info);
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* mtd_write(mtd, mtd_wunit_to_offset(mtd, blkoffs, wunit),
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* mtd->writesize, &retlen, buf + (i * mtd->writesize));
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* }
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*/
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int mtd_pairing_info_to_wunit(struct mtd_info *mtd,
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const struct mtd_pairing_info *info)
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{
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int ngroups = mtd_pairing_groups(mtd);
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int npairs = mtd_wunit_per_eb(mtd) / ngroups;
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if (!info || info->pair < 0 || info->pair >= npairs ||
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info->group < 0 || info->group >= ngroups)
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return -EINVAL;
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if (mtd->pairing && mtd->pairing->get_wunit)
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return mtd->pairing->get_wunit(mtd, info);
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return info->pair;
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}
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EXPORT_SYMBOL_GPL(mtd_pairing_info_to_wunit);
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/**
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* mtd_pairing_groups - get the number of pairing groups
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* @mtd: pointer to new MTD device info structure
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*
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* Returns the number of pairing groups.
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*
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* This number is usually equal to the number of bits exposed by a single
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* cell, and can be used in conjunction with mtd_pairing_info_to_wunit()
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* to iterate over all pages of a given pair.
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*/
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int mtd_pairing_groups(struct mtd_info *mtd)
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{
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if (!mtd->pairing || !mtd->pairing->ngroups)
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return 1;
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return mtd->pairing->ngroups;
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}
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EXPORT_SYMBOL_GPL(mtd_pairing_groups);
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/**
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* add_mtd_device - register an MTD device
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* @mtd: pointer to new MTD device info structure
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@ -409,6 +409,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
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slave->mtd.oobsize = master->oobsize;
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slave->mtd.oobavail = master->oobavail;
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slave->mtd.subpage_sft = master->subpage_sft;
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slave->mtd.pairing = master->pairing;
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slave->mtd.name = name;
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slave->mtd.owner = master->owner;
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@ -127,6 +127,82 @@ struct mtd_ooblayout_ops {
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struct mtd_oob_region *oobfree);
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};
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/**
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* struct mtd_pairing_info - page pairing information
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*
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* @pair: pair id
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* @group: group id
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*
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* The term "pair" is used here, even though TLC NANDs might group pages by 3
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* (3 bits in a single cell). A pair should regroup all pages that are sharing
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* the same cell. Pairs are then indexed in ascending order.
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*
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* @group is defining the position of a page in a given pair. It can also be
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* seen as the bit position in the cell: page attached to bit 0 belongs to
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* group 0, page attached to bit 1 belongs to group 1, etc.
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*
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* Example:
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* The H27UCG8T2BTR-BC datasheet describes the following pairing scheme:
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*
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* group-0 group-1
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*
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* pair-0 page-0 page-4
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* pair-1 page-1 page-5
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* pair-2 page-2 page-8
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* ...
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* pair-127 page-251 page-255
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*
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*
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* Note that the "group" and "pair" terms were extracted from Samsung and
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* Hynix datasheets, and might be referenced under other names in other
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* datasheets (Micron is describing this concept as "shared pages").
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*/
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struct mtd_pairing_info {
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int pair;
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int group;
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};
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/**
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* struct mtd_pairing_scheme - page pairing scheme description
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*
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* @ngroups: number of groups. Should be related to the number of bits
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* per cell.
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* @get_info: converts a write-unit (page number within an erase block) into
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* mtd_pairing information (pair + group). This function should
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* fill the info parameter based on the wunit index or return
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* -EINVAL if the wunit parameter is invalid.
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* @get_wunit: converts pairing information into a write-unit (page) number.
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* This function should return the wunit index pointed by the
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* pairing information described in the info argument. It should
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* return -EINVAL, if there's no wunit corresponding to the
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* passed pairing information.
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*
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* See mtd_pairing_info documentation for a detailed explanation of the
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* pair and group concepts.
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*
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* The mtd_pairing_scheme structure provides a generic solution to represent
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* NAND page pairing scheme. Instead of exposing two big tables to do the
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* write-unit <-> (pair + group) conversions, we ask the MTD drivers to
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* implement the ->get_info() and ->get_wunit() functions.
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*
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* MTD users will then be able to query these information by using the
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* mtd_pairing_info_to_wunit() and mtd_wunit_to_pairing_info() helpers.
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*
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* @ngroups is here to help MTD users iterating over all the pages in a
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* given pair. This value can be retrieved by MTD users using the
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* mtd_pairing_groups() helper.
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*
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* Examples are given in the mtd_pairing_info_to_wunit() and
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* mtd_wunit_to_pairing_info() documentation.
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*/
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struct mtd_pairing_scheme {
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int ngroups;
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int (*get_info)(struct mtd_info *mtd, int wunit,
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struct mtd_pairing_info *info);
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int (*get_wunit)(struct mtd_info *mtd,
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const struct mtd_pairing_info *info);
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};
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struct module; /* only needed for owner field in mtd_info */
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struct mtd_info {
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@ -188,6 +264,9 @@ struct mtd_info {
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/* OOB layout description */
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const struct mtd_ooblayout_ops *ooblayout;
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/* NAND pairing scheme, only provided for MLC/TLC NANDs */
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const struct mtd_pairing_scheme *pairing;
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/* the ecc step size. */
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unsigned int ecc_step_size;
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@ -296,6 +375,12 @@ static inline void mtd_set_ooblayout(struct mtd_info *mtd,
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mtd->ooblayout = ooblayout;
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}
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static inline void mtd_set_pairing_scheme(struct mtd_info *mtd,
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const struct mtd_pairing_scheme *pairing)
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{
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mtd->pairing = pairing;
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}
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static inline void mtd_set_of_node(struct mtd_info *mtd,
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struct device_node *np)
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{
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@ -312,6 +397,11 @@ static inline int mtd_oobavail(struct mtd_info *mtd, struct mtd_oob_ops *ops)
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return ops->mode == MTD_OPS_AUTO_OOB ? mtd->oobavail : mtd->oobsize;
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}
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int mtd_wunit_to_pairing_info(struct mtd_info *mtd, int wunit,
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struct mtd_pairing_info *info);
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int mtd_pairing_info_to_wunit(struct mtd_info *mtd,
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const struct mtd_pairing_info *info);
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int mtd_pairing_groups(struct mtd_info *mtd);
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int mtd_erase(struct mtd_info *mtd, struct erase_info *instr);
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int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
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void **virt, resource_size_t *phys);
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@ -397,6 +487,23 @@ static inline uint32_t mtd_mod_by_ws(uint64_t sz, struct mtd_info *mtd)
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return do_div(sz, mtd->writesize);
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}
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static inline int mtd_wunit_per_eb(struct mtd_info *mtd)
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{
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return mtd->erasesize / mtd->writesize;
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}
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static inline int mtd_offset_to_wunit(struct mtd_info *mtd, loff_t offs)
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{
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return mtd_div_by_ws(mtd_mod_by_eb(offs, mtd), mtd);
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}
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static inline loff_t mtd_wunit_to_offset(struct mtd_info *mtd, loff_t base,
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int wunit)
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{
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return base + (wunit * mtd->writesize);
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}
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static inline int mtd_has_oob(const struct mtd_info *mtd)
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{
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return mtd->_read_oob && mtd->_write_oob;
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