mtd: nand: drop EXPORT_SYMBOL_GPL for nanddev_erase()

This function is only used within this module, so it is no longer
necessary to use EXPORT_SYMBOL_GPL().

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20221018170205.1733958-1-dario.binacchi@amarulasolutions.com

mtd: Replace the expert mode symbols with a single helper

Reduce the number of exported symbols by replacing:
- mtd_expert_analysis_warning (the error string)
- mtd_expert_analysis_mode (the boolean)
with a single helper:
- mtd_check_expert_analysis_mode

Calling this helper will both check/return the content of the internal
boolean -which is not exported anymore- and as well conditionally
WARN_ONCE() the user, like it was done before.

While on this function, make the error string local to the helper and
set it const. Only export this helper when CONFIG_DEBUG_FS is defined to
limit the growth of the Linux kernel size only for a debug feature on
production kernels.

Mechanically update all the consumers.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220128113414.1121924-1-miquel.raynal@bootlin.com

mtd: nand: ecc: Add infrastructure to support hardware engines

Add the necessary helpers to register/unregister hardware ECC engines
that will be called from ECC engine drivers.

Also add helpers to get the right engine from the user
perspective. Keep a reference of the in use ECC engine in order to
prevent modules to be unloaded. Put the reference when the engine gets
retired.

A static list of hardware (only) ECC engines is setup to keep track of
the registered engines.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211216111654.238086-13-miquel.raynal@bootlin.com

mtd: Introduce an expert mode for forensics and debugging purposes

When developping NAND controller drivers or when debugging filesystem
corruptions, it is quite common to need hacking locally into the
MTD/NAND core in order to get access to the content of the bad
blocks. Instead of having multiple implementations out there let's
provide a simple yet effective specific MTD-wide debugfs entry to fully
disable these checks on purpose.

A warning is added to inform the user when this mode gets enabled.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211118114659.1282855-1-miquel.raynal@bootlin.com

mtd: nand: Add helpers to manage ECC engines and configurations

Add the logic in the NAND core to find the right ECC engine depending
on the NAND chip requirements and the user desires. Right now, the
choice may be made between (more will come):
* software Hamming
* software BCH
* on-die (SPI-NAND devices only)

Once the ECC engine has been found, the ECC engine must be
configured.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201001102014.20100-2-miquel.raynal@bootlin.com

mtd: nand: Add max_bad_eraseblocks_per_lun info to memorg

NAND datasheets usually give the maximum number of bad blocks per LUN
and this number can be used to help upper layers decide how much blocks
they should reserve for bad block handling.

Add a max_bad_eraseblocks_per_lun to the nand_memory_organization
struct and update the NAND_MEMORG() macro (and its users) accordingly.

We also provide a default mtd->_max_bad_blocks() implementation.

Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>

mtd: nand: Fix nanddev_mtd_erase()

Commit e7bfb3fdbde3 ("mtd: Stop updating erase_info->state and calling
mtd_erase_callback()") removed the einfo->state field and the
MTD_ERASE_XXX macros. At the same time, the generic NAND layer was added
and made sure to update the erase info state.

It did not result in a build failure after merging the nand/for-4.17
branch in mtd/next because the generic NAND layer is not selected yet.
Let's fix that before a config option starts selecting MTD_NAND_CORE.

Fixes: e7bfb3fdbde3 ("mtd: Stop updating erase_info->state and calling mtd_erase_callback()")
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

mtd: nand: Fix some function description mismatches in core.c

In core.c, some function descriptions do not match function
definitions. Just fix these mismatches.

Signed-off-by: Xiaolei Li <xiaolei.li@mediatek.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

mtd: nand: Add core infrastructure to deal with NAND devices

Add an intermediate layer to abstract NAND device interface so that
some logic can be shared between SPI NANDs, parallel/raw NANDs,
OneNANDs, ...

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>