Re: [PATCH v8 0/9] Support for block device NVMEM providers

[Srinivas Kandagatla <srini@kernel.org>]

On 7/3/26 2:45 PM, Loic Poulain wrote:
> On embedded devices, it is common for factory provisioning to store
> device-specific information, such as Ethernet or WiFi MAC addresses,
> in a dedicated area of an eMMC partition. This avoids the need for
> and additional EEPROM/OTP and leverages the persistence of eMMC.
> 
> One example is the Arduino UNO-Q, where the WiFi MAC address and the
> Bluetooth Device address are stored in the eMMC Boot1 partition.
> 
> Until now, accessing this information required a custom bootloader
> to read the data and inject it into the Device Tree before handing
> control over to the kernel. This approach is fragile and leads to
> device-specific workarounds.
> 
> Rather than adding a new NVMEM provider specifically to the eMMC
> subsystem, the new support operates at the block layer, allowing any
> block device to behave like other non-volatile memories such as EEPROM
> or OTP.
> 
> This series builds on earlier work by Daniel Golle that enables block
> devices to act as NVMEM providers:
> https://lore.kernel.org/all/6061aa4201030b9bb2f8d03ef32a564fdb786ed1.1709667858.git.daniel@makrotopia.org/
> 
> It also introduces an NVMEM layout description for the Arduino UNO-Q,
> allowing device-specific data stored in the eMMC Boot1 partition to
> be accessed in a standard way.
> 
> WiFi and Ethernet already support retrieving MAC addresses from NVMEM.
> Bluetooth requires similar support, which is also addressed.
> 
> Note that this is currently limited to MMC-backed block devices, as
> only the MMC core associates a firmware node with the block device
> (add_disk_fwnode). This can be easily extended in the future to
> support additional block drivers.
> 
> Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>

What is the merge strategy here, Am happy to take it via nvmem tree if
all the non nvmem patches are acked or reviewed-by.

--srini
> ---
> Changes in v8:
> - block: Fix bdev->bd_nvmem on registering failure (sashiko)
> - net: of_net: of_get_nvmem_eui48() now also rejects all-ones cells (sashiko)
> - Bluetooth: mgmt: account for HCI_QUIRK_USE_BDADDR_NVMEM in
>   is_configured() and get_missing_options() (sashiko)
> - Reword blk-nvmem KCONFIG help text to satisfy checkpatch
> - Link to v7: https://lore.kernel.org/r/20260701-block-as-nvmem-v7-0-3fe8205ef0a8@oss.qualcomm.com
> 
> Changes in v7:
> - Rework bindings/dts so that the eMMC boot partition can be a nvmem fixed-layout
>   and not a child of fixed-partition. (Rob)
> - Add Support for fixed-layout as the nvmem device node itself
> - Remove "block: partitions: of: Skip child nodes without reg property"
>   This is no more required in this series and will be submitted separately (Rob)
> - Add missing linux/cleanup.h and linux/device.h includes (Bartosz)
> - simplify nvmem_register() error path using dev_err_probe() (Bartosz)
> - nvmem_device forward declaration to blk_types.h (Bartosz)
> - Add hci_dev_get_bd_addr_from_nvmem() kernel-doc for return value (Piotr)
> - Link to v6: https://lore.kernel.org/r/20260629-block-as-nvmem-v6-0-f02513dcd46d@oss.qualcomm.com
> 
> Changes in v6:
> - blk_nvmem_add() returns int, error properly propagated (Bartosz)
> - Redundant if (bdev->bd_nvmem) guard removed in blk_nvmem_del() (Bartosz)
> - Size guard changed from UINT_MAX → INT_MAX to avoid signed overflow in config.size (sashiko)
> - BLK_OPEN_RESTRICT_WRITES removed from blk_nvmem_reg_read() (sashiko)
> - Link to v5: https://lore.kernel.org/r/20260612-block-as-nvmem-v5-0-95e0b30fff90@oss.qualcomm.com
> 
> Changes in v5:
> - Fixed ath10k binding issue + extended commit message (Krzysztof)
> - Moved blk-nvmem handling to block core instead of a class_interface
>   This allows correct/robust integration with block device life cycle (Bartosz).
> - block: partitions: of: Skip child nodes without reg property (sashiko)
> - Link to v4: https://lore.kernel.org/r/20260609-block-as-nvmem-v4-0-45712e6b22c6@oss.qualcomm.com
> 
> Changes in v4:
> - Fix squash issue (dts commit incorrectly squashed) (Konrad)
> - Use devres for nvmem resources (Bartosz)
> - use __free() destructor helper when possible (Bartosz)
> - Fix value return checking for bdev_file_open_by_dev
> - Link to v3: https://lore.kernel.org/r/20260608-block-as-nvmem-v3-0-82681f50aa35@oss.qualcomm.com
> 
> Changes in v3:
> - Fixed missing 'fixed-partitions' compatible in partition (Rob)
> - Fixed clashing nvmem cells, document calibration along mac (Sashiko)
> - Remove workaround to handle dangling nvmem references after
>   unregistering, this is a generic nvmem framework issue handled
>   in Bartosz's series:
>    https://lore.kernel.org/all/20260429-nvmem-unbind-v3-0-2a694f95395b@oss.qualcomm.com/
> - Validate mac (is_valid_ether_addr) before copying to output buffer
> - Link to v2: https://lore.kernel.org/r/20260507-block-as-nvmem-v2-0-bf17edd5134e@oss.qualcomm.com
> 
> Changes in v2:
> - Fix example nvmem-layout cells to use compatible = "mac-base"
> - Squash WiFi MAC and Bluetooth BD address consumer patches into the nvmem layout patch
> - Fix possible use-after-free in blk-nvmem: bnv (nvmem priv) linked to nvmem lifetime
> - Simplify nvmem-cell-names from items: - const: to plain const:
> - Factor out common NVMEM EUI-48 retrieval logic
> - Reorder changes
> - Link to v1: https://lore.kernel.org/r/20260428-block-as-nvmem-v1-0-6ad23e75190a@oss.qualcomm.com
> 
> ---
> Daniel Golle (1):
>       block: implement NVMEM provider
> 
> Loic Poulain (8):
>       dt-bindings: mmc: Document fixed-layout NVMEM provider support
>       dt-bindings: net: wireless: qcom,ath10k: Document NVMEM cells
>       dt-bindings: bluetooth: qcom: Add NVMEM BD address cell
>       nvmem: layouts: Support fixed-layout as the nvmem device node itself
>       net: of_net: Add of_get_nvmem_eui48() helper for EUI-48 lookup
>       Bluetooth: hci_sync: Add NVMEM-backed BD address retrieval
>       Bluetooth: qca: Set NVMEM BD address quirks when address is invalid
>       arm64: dts: qcom: arduino-imola: Describe NVMEM layout for WiFi/BT addresses
> 
>  .../devicetree/bindings/mmc/mmc-card.yaml          |  23 ++++-
>  .../net/bluetooth/qcom,bluetooth-common.yaml       |   9 ++
>  .../bindings/net/wireless/qcom,ath10k.yaml         |  16 +++
>  arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts |  32 ++++++
>  block/Kconfig                                      |  11 +++
>  block/Makefile                                     |   1 +
>  block/blk-nvmem.c                                  | 110 +++++++++++++++++++++
>  block/blk.h                                        |   8 ++
>  block/genhd.c                                      |   4 +
>  drivers/bluetooth/btqca.c                          |   5 +-
>  drivers/nvmem/layouts.c                            |  13 ++-
>  include/linux/blk_types.h                          |   4 +
>  include/linux/of_net.h                             |   7 ++
>  include/net/bluetooth/hci.h                        |  18 ++++
>  net/bluetooth/hci_sync.c                           |  41 +++++++-
>  net/bluetooth/mgmt.c                               |   6 +-
>  net/core/of_net.c                                  |  52 +++++++---
>  17 files changed, 342 insertions(+), 18 deletions(-)
> ---
> base-commit: dffcfe75c722be66aa2669fb335528edb0590671
> change-id: 20260428-block-as-nvmem-4b308e8bda9a
> 
> Best regards,