mtd: ubi: provide NVMEM layer over UBI volumes

In an ideal world we would like UBI to be used where ever possible on a
NAND chip. And with UBI support in ARM Trusted Firmware and U-Boot it
is possible to achieve an (almost-)all-UBI flash layout. Hence the need
for a way to also use UBI volumes to store board-level constants, such
as MAC addresses and calibration data of wireless interfaces.

Add UBI volume NVMEM driver module exposing UBI volumes as NVMEM
providers. Allow UBI devices to have a "volumes" firmware subnode with
volumes which may be compatible with "nvmem-cells".
Access to UBI volumes via the NVMEM interface at this point is
read-only, and it is slow, opening and closing the UBI volume for each
access due to limitations of the NVMEM provider API.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Richard Weinberger <richard@nod.at>

ubi: Use the fault injection framework to enhance the fault injection capability

To make debug parameters configurable at run time, use the
fault injection framework to reconstruct the debugfs interface,
and retain the legacy fault injection interface.

Now, the file emulate_failures and fault_attr files control whether
to enable fault emmulation.

The file emulate_failures receives a mask that controls type and
process of fault injection. Generally, for ease of use, you can
directly enter a mask with all 1s.

echo 0xffff > /sys/kernel/debug/ubi/ubi0/emulate_failures

And you need to configure other fault-injection capabilities for
testing purpose:

echo 100 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/probability
echo 15 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/space
echo 2 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/verbose
echo -1 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/times

The CONFIG_MTD_UBI_FAULT_INJECTION to enable the Fault Injection is
added to kconfig.

Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

UBI: Fix typos

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

UBI: block: Add CONFIG_BLOCK dependency

The UBI block driver depends on the block infrastructure. Add the
proper dependency and fix a build error when CONFIG_BLOCK is not selected.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: R/O block driver on top of UBI volumes

This commit introduces read-only block device emulation on top of UBI volumes.

Given UBI takes care of wear leveling and bad block management it's possible
to add a thin layer to enable block device access to UBI volumes.
This allows to use a block-oriented filesystem on a flash device.

The UBI block devices are meant to be used in conjunction with any
regular, block-oriented file system (e.g. ext4), although it's primarily
targeted at read-only file systems, such as squashfs.

Block devices are created upon user request through new ioctls:
UBI_IOCVOLATTBLK to attach and UBI_IOCVOLDETBLK to detach.
Also, a new UBI module parameter is added 'ubi.block'. This parameter is
needed in order to attach a block device on boot-up time, allowing to
mount the rootfs on a ubiblock device.
For instance, you could have these kernel parameters:

ubi.mtd=5 ubi.block=0,0 root=/dev/ubiblock0_0

Or, if you compile ubi as a module:

$ modprobe ubi mtd=/dev/mtd5 block=/dev/ubi0_0

Artem: amend commentaries and massage the patch a little bit.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: Wire-up fastmap

Make fastmap known to Kconfig, UBI Makefile and MAINTAINERS.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: add max_beb_per1024 to attach ioctl

This patch provides a possibility to set the "maximum expected number of
bad blocks per 1024 blocks" (max_beb_per1024) for each mtd device using
the UBI_IOCATT ioctl.

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: allow specifying bad PEBs limit using module parameter

This patch provides the possibility to adjust the "maximum expected number of
bad blocks per 1024 blocks" (max_beb_per1024) for each mtd device.

The majority of NAND devices have their max_beb_per1024 equal to 20, but
sometimes it's more.
Now, we can adjust that via a kernel parameter:
ubi.mtd=<name|num|path>[,<vid_hdr_offs>[,max_beb_per1024]]

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: use the whole MTD device size to get bad_peb_limit

On NAND flash devices, UBI reserves some physical erase blocks (PEB) for
bad block handling. Today, the number of reserved PEB can only be set as a
percentage of the total number of PEB in each MTD partition. For example, for a
NAND flash with 128KiB PEB, 2 MTD partition of 20MiB (mtd0) and 100MiB (mtd1)
and 2% reserved PEB:
- the UBI device on mtd0 will have 2 PEB reserved
- the UBI device on mtd1 will have 16 PEB reserved

The problem with this behaviour is that NAND flash manufacturers give a
minimum number of valid block (NVB) during the endurance life of the
device, e.g.:

Parameter Symbol Min Max Unit Notes
--------------------------------------------------------------
Valid block number NVB 1004 1024 Blocks 1

From this number we can deduce the maximum number of bad PEB that a device will
contain during its endurance life: a 128MiB NAND flash (1024 PEB) will not have
less than 20 bad blocks during the flash endurance life.

But the manufacturer doesn't tell where those bad block will appear. He doesn't
say either if they will be equally disposed on the whole device (and I'm pretty
sure they won't). So, according to the datasheets, we should reserve the
maximum number of bad PEB for each UBI device (worst case scenario: 20 bad
blocks appears on the smallest MTD partition).

So this patch make UBI use the whole MTD device size to calculate the maximum
bad expected eraseblocks.

The Kconfig option is in per1024 blocks, thus it can have a default value of 20
which is *very* common for NAND devices.

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: kill CONFIG_MTD_UBI_BEB_RESERVE

CONFIG_MTD_UBI_BEB_RESERVE and MIN_RESEVED_PEBS are no longer used,
since the amount of reserved eraseblocks for bad PEB handling is now
derived from 'ubi->bad_peb_limit' (ubi's maximum expected bad
eraseblocks).

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>

UBI: introduce new bad PEB limit

Introduce 'ubi->bad_peb_limit', which specifies an upper limit of PEBs
UBI expects to go bad. Currently, it is initialized to a fixed percentage
of total PEBs in the UBI device (configurable via CONFIG_MTD_UBI_BEB_LIMIT).

The 'bad_peb_limit' is intended to be used for calculating the amount of PEBs
UBI needs to reserve for bad eraseblock handling.

Artem: minor amendments.

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>

UBI: Change the default percentage of reserved PEB

The actual value (1%) is too low for actual NAND devices, a huge
majority of device has 2% maximum bad blocks (SLC or MLC).
(Actually it's 20 blocks on a 1024 blocks device, 40/2048...)

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>

UBI: remove Kconfig debugging option

This patch kills the UBI debugging Kconfig option completely and makes all the
debugging stuff to be always compiled-in. It was pain in the neck to maintain
this useless option because all users I am aware of have debugging enabled
anyway - how else will you diagnose errors otherwise?

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

UBI: do not select KALLSYMS_ALL

All UBI needs is to make sure we stacktraces when UBI debugging
is enabled. It is enough to select KALLSYMS for this, KALLSYMS_ALL
is not necessary.

And the current Kconfig line we have:

select KALLSYMS_ALL if KALLSYMS && DEBUG_KERNEL

is just too complex to be sane and right. But this "if" part there
is needed to prevent "unmet direct dependency" warnings, because
KALLSYMS_ALL depends on KALLSYMS and DEBUG_KERNEL, so we cannot
just select KALLSYMS_ALL.

Anyway, this feels messy, and we do not seem to really need KALLSYMS_ALL,
so select KALLSYMS instead.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>

UBI: make tests modes dynamic

Similarly to the debugging checks and message, make the test modes
be dynamically selected via the "debug_tsts" module parameter or
via the "/sys/module/ubi/parameters/debug_tsts" sysfs file. This
is consistent with UBIFS as well.

And now, since all the Kconfig knobs became dynamic, we can remove
the Kconfig.debug file completely.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBI: cleanup and simplify Kconfig

Cleanup the Kconfig for UBI by using menuconfig to enable/disable the entire
driver. Remove the dependency checks for MTD_UBI and MTD_UBI_DEBUG by
wrapping the options in if/endif blocks and remove any redundant checks.
Remove all default n since that is the Kconfig default. Change menu "Additional
UBI debugging messages" into a comment to remove one menu level.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBI: fix s/then/than/ typos

Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

Kconfig: Remove useless and sometimes wrong comments

Additionally, some excessive newlines removed.

Signed-off-by: Michael Roth <mroth@nessie.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

UBI: make gluebi a separate module

[Artem: re-worked the patch: made it release resources when the
module is unloaded, made it do module referencing, made it really
independent on UBI, tested it with the UBI test-suite which can
be found in ubi-2.6.git/tests/ubi-tests, re-named most of the
funcs/variables to get rid of the "ubi" word and make names
consistent.]

Signed-off-by: Dmitry Pervushin <dpervushin@embeddedalley.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBI: improve Kconfig documentation

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

UBI: Unsorted Block Images

UBI (Latin: "where?") manages multiple logical volumes on a single
flash device, specifically supporting NAND flash devices. UBI provides
a flexible partitioning concept which still allows for wear-levelling
across the whole flash device.

In a sense, UBI may be compared to the Logical Volume Manager
(LVM). Whereas LVM maps logical sector numbers to physical HDD sector
numbers, UBI maps logical eraseblocks to physical eraseblocks.

More information may be found at
http://www.linux-mtd.infradead.org/doc/ubi.html

Partitioning/Re-partitioning

An UBI volume occupies a certain number of erase blocks. This is
limited by a configured maximum volume size, which could also be
viewed as the partition size. Each individual UBI volume's size can
be changed independently of the other UBI volumes, provided that the
sum of all volume sizes doesn't exceed a certain limit.

UBI supports dynamic volumes and static volumes. Static volumes are
read-only and their contents are protected by CRC check sums.

Bad eraseblocks handling

UBI transparently handles bad eraseblocks. When a physical
eraseblock becomes bad, it is substituted by a good physical
eraseblock, and the user does not even notice this.

Scrubbing

On a NAND flash bit flips can occur on any write operation,
sometimes also on read. If bit flips persist on the device, at first
they can still be corrected by ECC, but once they accumulate,
correction will become impossible. Thus it is best to actively scrub
the affected eraseblock, by first copying it to a free eraseblock
and then erasing the original. The UBI layer performs this type of
scrubbing under the covers, transparently to the UBI volume users.

Erase Counts

UBI maintains an erase count header per eraseblock. This frees
higher-level layers (like file systems) from doing this and allows
for centralized erase count management instead. The erase counts are
used by the wear-levelling algorithm in the UBI layer. The algorithm
itself is exchangeable.

Booting from NAND

For booting directly from NAND flash the hardware must at least be
capable of fetching and executing a small portion of the NAND
flash. Some NAND flash controllers have this kind of support. They
usually limit the window to a few kilobytes in erase block 0. This
"initial program loader" (IPL) must then contain sufficient logic to
load and execute the next boot phase.

Due to bad eraseblocks, which may be randomly scattered over the
flash device, it is problematic to store the "secondary program
loader" (SPL) statically. Also, due to bit-flips it may become
corrupted over time. UBI allows to solve this problem gracefully by
storing the SPL in a small static UBI volume.

UBI volumes vs. static partitions

UBI volumes are still very similar to static MTD partitions:

* both consist of eraseblocks (logical eraseblocks in case of UBI
volumes, and physical eraseblocks in case of static partitions;
* both support three basic operations - read, write, erase.

But UBI volumes have the following advantages over traditional
static MTD partitions:

* there are no eraseblock wear-leveling constraints in case of UBI
volumes, so the user should not care about this;
* there are no bit-flips and bad eraseblocks in case of UBI volumes.

So, UBI volumes may be considered as flash devices with relaxed
restrictions.

Where can it be found?

Documentation, kernel code and applications can be found in the MTD
gits.

What are the applications for?

The applications help to create binary flash images for two purposes: pfi
files (partial flash images) for in-system update of UBI volumes, and plain
binary images, with or without OOB data in case of NAND, for a manufacturing
step. Furthermore some tools are/and will be created that allow flash content
analysis after a system has crashed..

Who did UBI?

The original ideas, where UBI is based on, were developed by Andreas
Arnez, Frank Haverkamp and Thomas Gleixner. Josh W. Boyer and some others
were involved too. The implementation of the kernel layer was done by Artem
B. Bityutskiy. The user-space applications and tools were written by Oliver
Lohmann with contributions from Frank Haverkamp, Andreas Arnez, and Artem.
Joern Engel contributed a patch which modifies JFFS2 so that it can be run on
a UBI volume. Thomas Gleixner did modifications to the NAND layer. Alexander
Schmidt made some testing work as well as core functionality improvements.

Signed-off-by: Artem B. Bityutskiy <dedekind@linutronix.de>
Signed-off-by: Frank Haverkamp <haver@vnet.ibm.com>