[PATCH v4 0/8] mtd: ubi: allow UBI volumes to provide NVMEM

[Daniel Golle]

The series is a follow-up and contains all patches of the previous
series "mtd: ubi: behave like a good MTD citizen"[1] which was meant in
preparation for implementing the NVMEM provider.

The goal is to support embedded Linux devices which got NVMEM bits
stored inside a UBI volume. Representing the UBI volume in the Device
Tree, adding a phandle to be referenced by NVMEM consumers allows such
devices to come up with their correct MAC addresses and device-specific
Wi-Fi calibration data loaded.

In order to be available for other drivers, attaching UBI devices has
to be moved from late_initcall (which is too late for other drivers) to
happen earlier. As an alternative to the existing kernel cmdline
parameter the Device Tree property 'compatible = "linux,ubi";' inside
an MTD partition can be used to have that MTD device attached as UBI
device. MTD partitions which serve as UBI devices may have a "volumes"
firmware subnode with volumes which may be compatible with
"nvmem-cells".

In this way, other drivers (think: Ethernet, Wi-Fi) can resolve and
acquire NVMEM bits using the usual device tree phandle, just this time
the NVMEM content is read from a UBI volume.

[1]: https://patchwork.ozlabs.org/project/linux-mtd/list/?series=353177&state=%2A&archive=both

Changes since v3:
 * dt-bindings fixes as requested

Changes since v2:
 * include dt-bindings additions

Changes since v1:
 * include patch to fix exiting Kconfig formatting issues
 * fix typo and indentation in Kconfig

Daniel Golle (8):
  dt-bindings: mtd: add basic bindings for UBI
  dt-bindings: mtd: nvmem-cells: add support for UBI volumes
  mtd: ubi: block: don't return on error when removing
  mtd: ubi: block: use notifier to create ubiblock
  mtd: ubi: attach MTD partition from device-tree
  mtd: ubi: introduce pre-removal notification for UBI volumes
  mtd: ubi: populate ubi volume fwnode
  mtd: ubi: provide NVMEM layer over UBI volumes

 .../bindings/mtd/partitions/linux,ubi.yaml    |  66 ++++++
 .../bindings/mtd/partitions/nvmem-cells.yaml  |   5 +-
 .../bindings/mtd/partitions/ubi-volume.yaml   |  36 ++++
 drivers/mtd/ubi/Kconfig                       |  12 ++
 drivers/mtd/ubi/Makefile                      |   1 +
 drivers/mtd/ubi/block.c                       | 186 ++++++++++-------
 drivers/mtd/ubi/build.c                       | 160 +++++++++++----
 drivers/mtd/ubi/cdev.c                        |   4 +-
 drivers/mtd/ubi/nvmem.c                       | 189 ++++++++++++++++++
 drivers/mtd/ubi/ubi.h                         |   6 +-
 drivers/mtd/ubi/vmt.c                         |  32 +++
 include/linux/mtd/ubi.h                       |   2 +
 12 files changed, 579 insertions(+), 120 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/mtd/partitions/linux,ubi.yaml
 create mode 100644 Documentation/devicetree/bindings/mtd/partitions/ubi-volume.yaml
 create mode 100644 drivers/mtd/ubi/nvmem.c

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2.41.0