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>
---
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):
block: partitions: of: Skip child nodes without reg property
dt-bindings: mmc: Document support for nvmem-layout
dt-bindings: net: wireless: qcom,ath10k: Document NVMEM cells
dt-bindings: bluetooth: qcom: Add NVMEM BD address cell
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 | 29 ++++++
.../net/bluetooth/qcom,bluetooth-common.yaml | 9 ++
.../bindings/net/wireless/qcom,ath10k.yaml | 16 +++
arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts | 39 ++++++++
block/Kconfig | 9 ++
block/Makefile | 1 +
block/blk-nvmem.c | 109 +++++++++++++++++++++
block/blk.h | 8 ++
block/genhd.c | 4 +
block/partitions/of.c | 20 ++--
drivers/bluetooth/btqca.c | 5 +-
include/linux/blk_types.h | 3 +
include/linux/blkdev.h | 1 +
include/linux/of_net.h | 7 ++
include/net/bluetooth/hci.h | 18 ++++
net/bluetooth/hci_sync.c | 39 +++++++-
net/core/of_net.c | 49 ++++++---
17 files changed, 345 insertions(+), 21 deletions(-)
---
base-commit: ccb7390d6cdb23b298a6e2a7028ec134dfc4db10
change-id: 20260428-block-as-nvmem-4b308e8bda9a
Best regards,
--
Loic Poulain <loic.poulain@oss.qualcomm.com>