Merge tag 'for-linus-20161008' of git://git.infradead.org/linux-mtd

Pull MTD updates from Brian Norris:
 "I've not been very active this cycle, so these are mostly from Boris,
  for the NAND flash subsystem.

  NAND:

   - Add the infrastructure to automate NAND timings configuration

   - Provide a generic DT property to maximize ECC strength

   - Some refactoring in the core bad block table handling, to help with
     improving some of the logic in error cases.

   - Minor cleanups and fixes

  MTD:

   - Add APIs for handling page pairing; this is necessary for reliably
     supporting MLC and TLC NAND flash, where paired-page disturbance
     affects reliability. Upper layers (e.g., UBI) should make use of
     these in the near future"

* tag 'for-linus-20161008' of git://git.infradead.org/linux-mtd: (35 commits)
  mtd: nand: fix trivial spelling error
  mtdpart: Propagate _get/put_device()
  mtd: nand: Provide nand_cleanup() function to free NAND related resources
  mtd: Kill the OF_MTD Kconfig option
  mtd: nand: mxc: Test CONFIG_OF instead of CONFIG_OF_MTD
  mtd: nand: Fix nand_command_lp() for 8bits opcodes
  mtd: nand: sunxi: Support ECC maximization
  mtd: nand: Support maximizing ECC when using software BCH
  mtd: nand: Add an option to maximize the ECC strength
  mtd: nand: mxc: Add timing setup for v2 controllers
  mtd: nand: mxc: implement onfi get/set features
  mtd: nand: sunxi: switch from manual to automated timing config
  mtd: nand: automate NAND timings selection
  mtd: nand: Expose data interface for ONFI mode 0
  mtd: nand: Add function to convert ONFI mode to data_interface
  mtd: nand: convert ONFI mode into data interface
  mtd: nand: Introduce nand_data_interface
  mtd: nand: Create a NAND reset function
  mtd: nand: remove unnecessary 'extern' from function declarations
  MAINTAINERS: Add maintainer entry for Ingenic JZ4780 NAND driver
  ...

1 files changed, 104 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
  *