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

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

[Loic Poulain]

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 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,
-- 
Loic Poulain <loic.poulain@oss.qualcomm.com>

[PATCH v8 1/9] dt-bindings: mmc: Document fixed-layout NVMEM provider support

[Loic Poulain]

Allow an eMMC hardware partition node to describe an NVMEM layout so the
partition can be exposed as an NVMEM provider. This lets a partition
(e.g. an eMMC boot partition) store device-specific information such as a
WiFi MAC address or a Bluetooth BD address and reference it through NVMEM
cells.

Accept "fixed-layout" as the partition node compatible, in addition to
"fixed-partitions", so the layout can be described directly on the
partition node.

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 .../devicetree/bindings/mmc/mmc-card.yaml          | 23 +++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.yaml b/Documentation/devicetree/bindings/mmc/mmc-card.yaml
index a61d6c96df759102f9c1fbfd548b026a77921cae..0422894508478c8d0ca68292b58a5fdbee218358 100644
--- a/Documentation/devicetree/bindings/mmc/mmc-card.yaml
+++ b/Documentation/devicetree/bindings/mmc/mmc-card.yaml
@@ -38,7 +38,9 @@ patternProperties:
     properties:
       compatible:
         contains:
-          const: fixed-partitions
+          enum:
+            - fixed-partitions
+            - fixed-layout
 
 required:
   - compatible
@@ -86,6 +88,25 @@ examples:
                     read-only;
                 };
             };
+
+            partitions-boot2 {
+                compatible = "fixed-layout";
+
+                #address-cells = <1>;
+                #size-cells = <1>;
+
+                mac-addr@4400 {
+                    compatible = "mac-base";
+                    reg = <0x4400 0x6>;
+                    #nvmem-cell-cells = <1>;
+                };
+
+                bd-addr@5400 {
+                    compatible = "mac-base";
+                    reg = <0x5400 0x6>;
+                    #nvmem-cell-cells = <1>;
+                };
+            };
         };
     };
 

-- 
2.34.1

[PATCH v8 2/9] dt-bindings: net: wireless: qcom,ath10k: Document NVMEM cells

[Loic Poulain]

Document the NVMEM cells supported by the ath10k driver, the
mac-address, pre-calibration data, and calibration data.

Since such data may also originate from chipset OTP or be supplied
via other device tree structures. All of these cells are optional
and can be provided independently, in any combination.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 .../devicetree/bindings/net/wireless/qcom,ath10k.yaml    | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.yaml b/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.yaml
index c21d66c7cd558ab792524be9afec8b79272d1c87..878c5d833a9cb073520c256c1b72d0f1489e7f4a 100644
--- a/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.yaml
+++ b/Documentation/devicetree/bindings/net/wireless/qcom,ath10k.yaml
@@ -92,6 +92,22 @@ properties:
 
   ieee80211-freq-limit: true
 
+  nvmem-cells:
+    minItems: 1
+    maxItems: 3
+    description:
+      References to nvmem cells for MAC address and/or calibration data.
+      Supported cell names are mac-address, calibration, and pre-calibration.
+
+  nvmem-cell-names:
+    minItems: 1
+    maxItems: 3
+    items:
+      enum:
+        - mac-address
+        - calibration
+        - pre-calibration
+
   qcom,calibration-data:
     $ref: /schemas/types.yaml#/definitions/uint8-array
     description:

-- 
2.34.1

[PATCH v8 3/9] dt-bindings: bluetooth: qcom: Add NVMEM BD address cell

[Loic Poulain]

Add support for an NVMEM cell provider for "local-bd-address",
allowing the Bluetooth stack to retrieve controller's BD address
from non-volatile storage such as an EEPROM or an eMMC partition.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 .../devicetree/bindings/net/bluetooth/qcom,bluetooth-common.yaml | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/bluetooth/qcom,bluetooth-common.yaml b/Documentation/devicetree/bindings/net/bluetooth/qcom,bluetooth-common.yaml
index c8e9c55c1afb4c8e05ba2dae41ce2db4194b4a0f..7cb28f30c9af032082f23311f2fc89a32f266f17 100644
--- a/Documentation/devicetree/bindings/net/bluetooth/qcom,bluetooth-common.yaml
+++ b/Documentation/devicetree/bindings/net/bluetooth/qcom,bluetooth-common.yaml
@@ -22,4 +22,13 @@ properties:
     description:
       boot firmware is incorrectly passing the address in big-endian order
 
+  nvmem-cells:
+    maxItems: 1
+    description:
+      Nvmem data cell that contains a 6 byte BD address with the most
+      significant byte first (big-endian).
+
+  nvmem-cell-names:
+    const: local-bd-address
+
 additionalProperties: true

-- 
2.34.1

[PATCH v8 4/9] nvmem: layouts: Support fixed-layout as the nvmem device node itself

[Loic Poulain]

of_nvmem_layout_get_container() only looks for a child node named
"nvmem-layout" to locate the cell definitions. This does not cover
providers whose device tree node is itself the fixed-layout container,
such as an eMMC boot partition block device whose fwnode points directly
at a "fixed-layout" compatible partitions node.

When no "nvmem-layout" child is present, fall back to returning the nvmem
device node itself if it is compatible with "fixed-layout", so that its
cells are parsed by nvmem_add_cells_from_fixed_layout().

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/nvmem/layouts.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/layouts.c b/drivers/nvmem/layouts.c
index b90584e1b99eab4217cbe7ec48373e18a7caf0dc..efa631ce7283bdd6c8ecda75915911b5e3a33c99 100644
--- a/drivers/nvmem/layouts.c
+++ b/drivers/nvmem/layouts.c
@@ -167,7 +167,18 @@ static int nvmem_layout_bus_populate(struct nvmem_device *nvmem,
 
 struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
 {
-	return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
+	struct device_node *np;
+
+	/* Search for nvmem-layout child */
+	np = of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
+	if (np)
+		return np;
+
+	/* The nvmem of_node is itself a fixed-layout node */
+	if (of_device_is_compatible(nvmem->dev.of_node, "fixed-layout"))
+		return of_node_get(nvmem->dev.of_node);
+
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
 

-- 
2.34.1

Re: [PATCH v8 4/9] nvmem: layouts: Support fixed-layout as the nvmem device node itself

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Double parsing of NVMEM cells leading to duplicate sysfs entries and device probe failure when a legacy provider adds the `fixed-layout` compatible string.
--

commit 5ae6267ddd6db9a2a2626cb61243805bccbca0b9
Author: Loic Poulain <loic.poulain@oss.qualcomm.com>

nvmem: layouts: Support fixed-layout as the nvmem device node itself

This commit modifies of_nvmem_layout_get_container() to return the nvmem
device node itself if it lacks an "nvmem-layout" child but has the
"fixed-layout" compatible string.

> diff --git a/drivers/nvmem/layouts.c b/drivers/nvmem/layouts.c
> index b90584e1b99ea..efa631ce7283b 100644
> --- a/drivers/nvmem/layouts.c
> +++ b/drivers/nvmem/layouts.c
> @@ -167,7 +167,18 @@ static int nvmem_layout_bus_populate(struct nvmem_device *nvmem,
>  
>  struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
>  {
> -	return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
> +	struct device_node *np;
> +
> +	/* Search for nvmem-layout child */
> +	np = of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
> +	if (np)
> +		return np;
> +
> +	/* The nvmem of_node is itself a fixed-layout node */
> +	if (of_device_is_compatible(nvmem->dev.of_node, "fixed-layout"))
> +		return of_node_get(nvmem->dev.of_node);

[Severity: Medium]
Could this lead to double parsing of NVMEM cells and device probe failures
for legacy providers?

If a legacy provider (which sets config->add_legacy_fixed_of_cells = true
in its driver) updates its device tree node to include the "fixed-layout"
compatible string, it looks like nvmem_register() might parse the cells
twice:

drivers/nvmem/core.c:nvmem_register() {
        ...
        if (config->add_legacy_fixed_of_cells) {
                rval = nvmem_add_cells_from_legacy_of(nvmem);
                if (rval)
                        goto err_remove_cells;
        }

        rval = nvmem_add_cells_from_fixed_layout(nvmem);
        if (rval)
                goto err_remove_cells;
        ...
}

Because of_nvmem_layout_get_container() now returns the nvmem device node
itself, both functions would process the same child nodes.

Would nvmem_populate_sysfs_cells() then fail with -EEXIST due to duplicate
sysfs entries and abort the device registration?

> +
> +	return NULL;
>  }
>  EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260703-block-as-nvmem-v8-0-98ae32bfc49a@oss.qualcomm.com?part=4

[PATCH v8 5/9] block: implement NVMEM provider

[Loic Poulain]

From: Daniel Golle <daniel@makrotopia.org>

On embedded devices using an eMMC it is common that one or more partitions
on the eMMC are used to store MAC addresses and Wi-Fi calibration EEPROM
data. Allow referencing the partition in device tree for the kernel and
Wi-Fi drivers accessing it via the NVMEM layer.

NVMEM is registered for a block device whose OF node describes an NVMEM
layout, either via an "nvmem-layout" child or by being a "fixed-layout"
node itself (e.g. an eMMC boot partition associated through its mmc-card
node).

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Co-developed-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 block/Kconfig             |  11 +++++
 block/Makefile            |   1 +
 block/blk-nvmem.c         | 110 ++++++++++++++++++++++++++++++++++++++++++++++
 block/blk.h               |   8 ++++
 block/genhd.c             |   4 ++
 include/linux/blk_types.h |   4 ++
 6 files changed, 138 insertions(+)

diff --git a/block/Kconfig b/block/Kconfig
index 15027963472d7b40e27b9097a5993c457b5b3054..69370ea2e268b9e5320477c747db4aab15abe3ff 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -209,6 +209,17 @@ config BLK_INLINE_ENCRYPTION_FALLBACK
 	  by falling back to the kernel crypto API when inline
 	  encryption hardware is not present.
 
+config BLK_NVMEM
+	bool "Block device NVMEM provider"
+	depends on OF
+	depends on NVMEM
+	help
+	  Allow block devices (or partitions) to act as NVMEM providers,
+	  exposing factory-provisioned data such as MAC addresses or Wi-Fi
+	  calibration blobs to the drivers that consume them. This is
+	  typically used on embedded devices where such data is stored in a
+	  dedicated area of an eMMC, instead of a separate EEPROM or OTP.
+
 source "block/partitions/Kconfig"
 
 config BLK_PM
diff --git a/block/Makefile b/block/Makefile
index 7dce2e44276c4274c11a0a61121c83d9c43d6e0c..d7ac389e71902bc091a8800ea266190a43b3e63d 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -36,3 +36,4 @@ obj-$(CONFIG_BLK_INLINE_ENCRYPTION)	+= blk-crypto.o blk-crypto-profile.o \
 					   blk-crypto-sysfs.o
 obj-$(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK)	+= blk-crypto-fallback.o
 obj-$(CONFIG_BLOCK_HOLDER_DEPRECATED)	+= holder.o
+obj-$(CONFIG_BLK_NVMEM)                += blk-nvmem.o
diff --git a/block/blk-nvmem.c b/block/blk-nvmem.c
new file mode 100644
index 0000000000000000000000000000000000000000..642a12f8a8b1c88e25baa1b684adef48c8c91c84
--- /dev/null
+++ b/block/blk-nvmem.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * block device NVMEM provider
+ *
+ * Copyright (c) 2024 Daniel Golle <daniel@makrotopia.org>
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ *
+ * Useful on devices using a partition on an eMMC for MAC addresses or
+ * Wi-Fi calibration EEPROM data.
+ */
+
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/file.h>
+#include <linux/nvmem-provider.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of.h>
+#include <linux/pagemap.h>
+#include <linux/property.h>
+
+#include "blk.h"
+
+static int blk_nvmem_reg_read(void *priv, unsigned int from, void *val, size_t bytes)
+{
+	dev_t devt = (dev_t)(uintptr_t)priv;
+	size_t bytes_left = bytes;
+	loff_t pos = from;
+	int ret = 0;
+
+	struct file *bdev_file __free(fput) =
+		bdev_file_open_by_dev(devt, BLK_OPEN_READ, NULL, NULL);
+	if (IS_ERR(bdev_file))
+		return PTR_ERR(bdev_file);
+
+	while (bytes_left) {
+		pgoff_t f_index = pos >> PAGE_SHIFT;
+		struct folio *folio;
+		size_t folio_off;
+		size_t to_read;
+
+		folio = read_mapping_folio(bdev_file->f_mapping, f_index, NULL);
+		if (IS_ERR(folio)) {
+			ret = PTR_ERR(folio);
+			break;
+		}
+
+		folio_off = offset_in_folio(folio, pos);
+		to_read = min(bytes_left, folio_size(folio) - folio_off);
+		memcpy_from_folio(val, folio, folio_off, to_read);
+		pos += to_read;
+		bytes_left -= to_read;
+		val += to_read;
+		folio_put(folio);
+	}
+
+	return ret;
+}
+
+int blk_nvmem_add(struct block_device *bdev)
+{
+	struct device *dev = &bdev->bd_device;
+	struct nvmem_config config = {};
+	struct nvmem_device *nvmem;
+
+	/* skip devices which do not have a device tree node */
+	if (!dev_of_node(dev))
+		return 0;
+
+	/* skip devices without an nvmem layout defined */
+	struct device_node *child __free(device_node) =
+		of_get_child_by_name(dev_of_node(dev), "nvmem-layout");
+	if (!child && !of_device_is_compatible(dev_of_node(dev), "fixed-layout"))
+		return 0;
+
+	/*
+	 * skip block device too large to be represented as NVMEM devices,
+	 * nvmem_config.size is a signed int
+	 */
+	if (bdev_nr_bytes(bdev) > INT_MAX) {
+		dev_warn(dev, "block device too large to be an NVMEM provider\n");
+		return 0;
+	}
+
+	config.id = NVMEM_DEVID_NONE;
+	config.dev = dev;
+	config.name = dev_name(dev);
+	config.owner = THIS_MODULE;
+	config.priv = (void *)(uintptr_t)dev->devt;
+	config.reg_read = blk_nvmem_reg_read;
+	config.size = bdev_nr_bytes(bdev);
+	config.word_size = 1;
+	config.stride = 1;
+	config.read_only = true;
+	config.root_only = true;
+	config.ignore_wp = true;
+	config.of_node = to_of_node(dev->fwnode);
+
+	nvmem = nvmem_register(&config);
+	if (IS_ERR(nvmem))
+		return dev_err_probe(dev, PTR_ERR(nvmem), "Failed to register NVMEM device\n");
+
+	bdev->bd_nvmem = nvmem;
+	return 0;
+}
+
+void blk_nvmem_del(struct block_device *bdev)
+{
+	nvmem_unregister(bdev->bd_nvmem);
+	bdev->bd_nvmem = NULL;
+}
diff --git a/block/blk.h b/block/blk.h
index ec4674cdf2ead4fd259ff5fc42401f591e684ee9..ed0c10168ba7be10855509637f824a9cea2b9ccb 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -757,4 +757,12 @@ static inline void blk_debugfs_unlock(struct request_queue *q,
 	memalloc_noio_restore(memflags);
 }
 
+#ifdef CONFIG_BLK_NVMEM
+int blk_nvmem_add(struct block_device *bdev);
+void blk_nvmem_del(struct block_device *bdev);
+#else
+static inline int blk_nvmem_add(struct block_device *bdev) { return 0; }
+static inline void blk_nvmem_del(struct block_device *bdev) {}
+#endif
+
 #endif /* BLK_INTERNAL_H */
diff --git a/block/genhd.c b/block/genhd.c
index 7d6854fd28e95ae9134309679a7c6a937f5b7db8..1b2382de6fb30c1e5f60f45c04dc03ed3bf5d5f2 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -421,6 +421,8 @@ static void add_disk_final(struct gendisk *disk)
 		 */
 		dev_set_uevent_suppress(ddev, 0);
 		disk_uevent(disk, KOBJ_ADD);
+
+		blk_nvmem_add(disk->part0);
 	}
 
 	blk_apply_bdi_limits(disk->bdi, &disk->queue->limits);
@@ -704,6 +706,8 @@ static void __del_gendisk(struct gendisk *disk)
 
 	disk_del_events(disk);
 
+	blk_nvmem_del(disk->part0);
+
 	/*
 	 * Prevent new openers by unlinked the bdev inode.
 	 */
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 8808ee76e73c09e0ceaac41ba59e86fb0c4efc64..6ed173c649025b95cce9253b27f68f2c7dbab8eb 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -15,6 +15,7 @@
 struct bio_set;
 struct bio;
 struct bio_integrity_payload;
+struct nvmem_device;
 struct page;
 struct io_context;
 struct cgroup_subsys_state;
@@ -73,6 +74,9 @@ struct block_device {
 	int			bd_writers;
 #ifdef CONFIG_SECURITY
 	void			*bd_security;
+#endif
+#ifdef CONFIG_BLK_NVMEM
+	struct nvmem_device	*bd_nvmem;
 #endif
 	/*
 	 * keep this out-of-line as it's both big and not needed in the fast

-- 
2.34.1

Re: [PATCH v8 5/9] block: implement NVMEM provider

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The NVMEM provider incorrectly sets `config.owner = THIS_MODULE`, failing to pin the underlying block device driver module and causing a Use-After-Free if the driver module is unloaded while a consumer holds an NVMEM cell.
--

commit 658c388a96462e54e252d777f2fc96dcf4f36d59
Author: Daniel Golle <daniel@makrotopia.org>

block: implement NVMEM provider

This patch allows block devices or partitions to act as NVMEM providers,
exposing factory-provisioned data such as MAC addresses or Wi-Fi calibration
blobs. It introduces blk_nvmem_add to register the block device with the
NVMEM framework when the appropriate device tree nodes are present.

> diff --git a/block/blk-nvmem.c b/block/blk-nvmem.c
> new file mode 100644
> index 0000000000000..642a12f8a8b1c
> --- /dev/null
> +++ b/block/blk-nvmem.c

[ ... ]

> +int blk_nvmem_add(struct block_device *bdev)
> +{
> +	struct device *dev = &bdev->bd_device;
> +	struct nvmem_config config = {};
> +	struct nvmem_device *nvmem;

[ ... ]

> +	config.id = NVMEM_DEVID_NONE;
> +	config.dev = dev;
> +	config.name = dev_name(dev);
> +	config.owner = THIS_MODULE;

[Severity: High]
Should this owner be set to the block device driver's module, such as
bdev->bd_disk->fops->owner, instead of THIS_MODULE?

By setting config.owner to THIS_MODULE, it seems we pin the block core
module but fail to protect the actual block device driver (like mmc_block)
from being unloaded while a consumer still holds a reference to the NVMEM
cell. 

If the driver module is unloaded, its module memory is freed. When the
consumer later releases the cell and the bd_device refcount drops to zero,
could disk_release() end up calling disk->fops->free_disk on a now-unmapped
driver module pointer and cause a crash?

> +	config.priv = (void *)(uintptr_t)dev->devt;
> +	config.reg_read = blk_nvmem_reg_read;
> +	config.size = bdev_nr_bytes(bdev);

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260703-block-as-nvmem-v8-0-98ae32bfc49a@oss.qualcomm.com?part=5

[PATCH v8 6/9] net: of_net: Add of_get_nvmem_eui48() helper for EUI-48 lookup

[Loic Poulain]

Factor out the common NVMEM EUI-48 retrieval logic from
of_get_mac_address_nvmem() into a new of_get_nvmem_eui48() helper that
accepts the NVMEM cell name as a parameter. This allows other subsystems
(e.g. Bluetooth) to reuse the same lookup-validate-copy pattern with a
different cell name, without duplicating code.

of_get_mac_address_nvmem() is updated to call of_get_nvmem_eui48() with
"mac-address", preserving its existing behavior.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 include/linux/of_net.h |  7 +++++++
 net/core/of_net.c      | 52 ++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 47 insertions(+), 12 deletions(-)

diff --git a/include/linux/of_net.h b/include/linux/of_net.h
index d88715a0b3a52f87af23d47791bea3baf5be5200..7854ba555d9a55f3d020a37fe00a27ae52e0e5dc 100644
--- a/include/linux/of_net.h
+++ b/include/linux/of_net.h
@@ -15,6 +15,7 @@ struct net_device;
 extern int of_get_phy_mode(struct device_node *np, phy_interface_t *interface);
 extern int of_get_mac_address(struct device_node *np, u8 *mac);
 extern int of_get_mac_address_nvmem(struct device_node *np, u8 *mac);
+int of_get_nvmem_eui48(struct device_node *np, const char *cell_name, u8 *addr);
 int of_get_ethdev_address(struct device_node *np, struct net_device *dev);
 extern struct net_device *of_find_net_device_by_node(struct device_node *np);
 #else
@@ -34,6 +35,12 @@ static inline int of_get_mac_address_nvmem(struct device_node *np, u8 *mac)
 	return -ENODEV;
 }
 
+static inline int of_get_nvmem_eui48(struct device_node *np,
+				      const char *cell_name, u8 *addr)
+{
+	return -ENODEV;
+}
+
 static inline int of_get_ethdev_address(struct device_node *np, struct net_device *dev)
 {
 	return -ENODEV;
diff --git a/net/core/of_net.c b/net/core/of_net.c
index 93ea425b9248a23f4f95a336e9cdbf0053248e32..999ca0e9258c41580823b80e0ef6db26617bc968 100644
--- a/net/core/of_net.c
+++ b/net/core/of_net.c
@@ -61,9 +61,7 @@ static int of_get_mac_addr(struct device_node *np, const char *name, u8 *addr)
 int of_get_mac_address_nvmem(struct device_node *np, u8 *addr)
 {
 	struct platform_device *pdev = of_find_device_by_node(np);
-	struct nvmem_cell *cell;
-	const void *mac;
-	size_t len;
+	u8 mac[ETH_ALEN] __aligned(sizeof(u16));
 	int ret;
 
 	/* Try lookup by device first, there might be a nvmem_cell_lookup
@@ -75,27 +73,57 @@ int of_get_mac_address_nvmem(struct device_node *np, u8 *addr)
 		return ret;
 	}
 
-	cell = of_nvmem_cell_get(np, "mac-address");
+	ret = of_get_nvmem_eui48(np, "mac-address", mac);
+	if (ret)
+		return ret;
+
+	if (!is_valid_ether_addr(mac))
+		return -EINVAL;
+
+	memcpy(addr, mac, ETH_ALEN);
+	return 0;
+}
+EXPORT_SYMBOL(of_get_mac_address_nvmem);
+
+/**
+ * of_get_nvmem_eui48 - Read a 6-byte EUI-48 address from a named NVMEM cell.
+ * @np:		Device node to look up the NVMEM cell from.
+ * @cell_name:	Name of the NVMEM cell (e.g. "mac-address", "local-bd-address").
+ * @addr:	Output buffer for the 6-byte address.
+ *
+ * Reads the named NVMEM cell and validates that it contains a non-zero 6-byte
+ * address. Returns 0 on success, negative errno on failure.
+ */
+int of_get_nvmem_eui48(struct device_node *np, const char *cell_name, u8 *addr)
+{
+	struct nvmem_cell *cell;
+	const void *eui48;
+	size_t len;
+
+	cell = of_nvmem_cell_get(np, cell_name);
 	if (IS_ERR(cell))
 		return PTR_ERR(cell);
 
-	mac = nvmem_cell_read(cell, &len);
+	eui48 = nvmem_cell_read(cell, &len);
 	nvmem_cell_put(cell);
 
-	if (IS_ERR(mac))
-		return PTR_ERR(mac);
+	if (IS_ERR(eui48))
+		return PTR_ERR(eui48);
 
-	if (len != ETH_ALEN || !is_valid_ether_addr(mac)) {
-		kfree(mac);
+	/* Reject unprogrammed cells that read as all-zeroes or all-ones */
+	if (len != ETH_ALEN ||
+	    !memchr_inv(eui48, 0x00, ETH_ALEN) ||
+	    !memchr_inv(eui48, 0xff, ETH_ALEN)) {
+		kfree(eui48);
 		return -EINVAL;
 	}
 
-	memcpy(addr, mac, ETH_ALEN);
-	kfree(mac);
+	memcpy(addr, eui48, ETH_ALEN);
+	kfree(eui48);
 
 	return 0;
 }
-EXPORT_SYMBOL(of_get_mac_address_nvmem);
+EXPORT_SYMBOL_GPL(of_get_nvmem_eui48);
 
 /**
  * of_get_mac_address()

-- 
2.34.1

[PATCH v8 7/9] Bluetooth: hci_sync: Add NVMEM-backed BD address retrieval

[Loic Poulain]

Some devices store the Bluetooth BD address in non-volatile
memory, which can be accessed through the NVMEM framework.
Similar to Ethernet or WiFi MAC addresses, add support for
reading the BD address from a 'local-bd-address' NVMEM cell.

As with the device-tree provided BD address, add a quirk to
indicate whether a device or platform should attempt to read
the address from NVMEM when no valid in-chip address is present.
Also add a quirk to indicate if the address is stored in
big-endian byte order.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Piotr Kwapulinski <piotr.kwapulinski@intel.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 include/net/bluetooth/hci.h | 18 ++++++++++++++++++
 net/bluetooth/hci_sync.c    | 41 ++++++++++++++++++++++++++++++++++++++++-
 net/bluetooth/mgmt.c        |  6 ++++--
 3 files changed, 62 insertions(+), 3 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 572b1c620c5d653a1fe10b26c1b0ba33e8f4968f..7686466d1109253b0d75edeb5f6a99fb98ce4cc6 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -164,6 +164,24 @@ enum {
 	 */
 	HCI_QUIRK_BDADDR_PROPERTY_BROKEN,
 
+	/* When this quirk is set, the public Bluetooth address
+	 * initially reported by HCI Read BD Address command
+	 * is considered invalid. The public BD Address can be
+	 * retrieved via a 'local-bd-address' NVMEM cell.
+	 *
+	 * This quirk can be set before hci_register_dev is called or
+	 * during the hdev->setup vendor callback.
+	 */
+	HCI_QUIRK_USE_BDADDR_NVMEM,
+
+	/* When this quirk is set, the Bluetooth Device Address provided by
+	 * the 'local-bd-address' NVMEM is stored in big-endian order.
+	 *
+	 * This quirk can be set before hci_register_dev is called or
+	 * during the hdev->setup vendor callback.
+	 */
+	HCI_QUIRK_BDADDR_NVMEM_BE,
+
 	/* When this quirk is set, the duplicate filtering during
 	 * scanning is based on Bluetooth devices addresses. To allow
 	 * RSSI based updates, restart scanning if needed.
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index fd3aacdea512a37c22b9a2be90c89ddca4b4d99f..56248d4abcb5b1d9993962a9f6bf60bf865b8d7b 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/property.h>
+#include <linux/of_net.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
@@ -3588,6 +3589,39 @@ int hci_powered_update_sync(struct hci_dev *hdev)
 	return 0;
 }
 
+/**
+ * hci_dev_get_bd_addr_from_nvmem - Get the Bluetooth Device Address
+ *				    (BD_ADDR) for a HCI device from
+ *				    an NVMEM cell.
+ * @hdev:	The HCI device
+ *
+ * Search for 'local-bd-address' NVMEM cell in the device firmware node.
+ *
+ * All-zero BD addresses are rejected (unprovisioned).
+ *
+ * Return: 0 on success, or a negative error code on failure.
+ */
+static int hci_dev_get_bd_addr_from_nvmem(struct hci_dev *hdev)
+{
+	struct device_node *np = dev_of_node(hdev->dev.parent);
+	u8 ba[sizeof(bdaddr_t)];
+	int err;
+
+	if (!np)
+		return -ENODEV;
+
+	err = of_get_nvmem_eui48(np, "local-bd-address", ba);
+	if (err)
+		return err;
+
+	if (hci_test_quirk(hdev, HCI_QUIRK_BDADDR_NVMEM_BE))
+		baswap(&hdev->public_addr, (bdaddr_t *)ba);
+	else
+		bacpy(&hdev->public_addr, (bdaddr_t *)ba);
+
+	return 0;
+}
+
 /**
  * hci_dev_get_bd_addr_from_property - Get the Bluetooth Device Address
  *				       (BD_ADDR) for a HCI device from
@@ -5042,12 +5076,17 @@ static int hci_dev_setup_sync(struct hci_dev *hdev)
 	 * its setup callback.
 	 */
 	invalid_bdaddr = hci_test_quirk(hdev, HCI_QUIRK_INVALID_BDADDR) ||
-			 hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY);
+			 hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY) ||
+			 hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_NVMEM);
 	if (!ret) {
 		if (hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY) &&
 		    !bacmp(&hdev->public_addr, BDADDR_ANY))
 			hci_dev_get_bd_addr_from_property(hdev);
 
+		if (hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_NVMEM) &&
+		    !bacmp(&hdev->public_addr, BDADDR_ANY))
+			hci_dev_get_bd_addr_from_nvmem(hdev);
+
 		if (invalid_bdaddr && bacmp(&hdev->public_addr, BDADDR_ANY) &&
 		    hdev->set_bdaddr) {
 			ret = hdev->set_bdaddr(hdev, &hdev->public_addr);
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index b05bb380e5f87715e2a4ac38aa7e7eb77c48549f..8f2a2d0f76adc3dd9cbe235d5ad0ed5e1667fcb6 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -617,7 +617,8 @@ static bool is_configured(struct hci_dev *hdev)
 		return false;
 
 	if ((hci_test_quirk(hdev, HCI_QUIRK_INVALID_BDADDR) ||
-	     hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY)) &&
+	     hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY) ||
+	     hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_NVMEM)) &&
 	    !bacmp(&hdev->public_addr, BDADDR_ANY))
 		return false;
 
@@ -633,7 +634,8 @@ static __le32 get_missing_options(struct hci_dev *hdev)
 		options |= MGMT_OPTION_EXTERNAL_CONFIG;
 
 	if ((hci_test_quirk(hdev, HCI_QUIRK_INVALID_BDADDR) ||
-	     hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY)) &&
+	     hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY) ||
+	     hci_test_quirk(hdev, HCI_QUIRK_USE_BDADDR_NVMEM)) &&
 	    !bacmp(&hdev->public_addr, BDADDR_ANY))
 		options |= MGMT_OPTION_PUBLIC_ADDRESS;
 

-- 
2.34.1

[PATCH v8 8/9] Bluetooth: qca: Set NVMEM BD address quirks when address is invalid

[Loic Poulain]

When the controller BD address is invalid (zero or default),
set the NVMEM quirks to allow retrieving the address from a
'local-bd-address' NVMEM cell. The BD address is often stored
alongside the WiFi MAC address in big-endian format, so also
set the big-endian quirk.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 drivers/bluetooth/btqca.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
index dda76365726f0bfe0e80e05fe04859fa4f0592e1..df33eacfd29fa680f393f90215150743e6001d5b 100644
--- a/drivers/bluetooth/btqca.c
+++ b/drivers/bluetooth/btqca.c
@@ -721,8 +721,11 @@ static int qca_check_bdaddr(struct hci_dev *hdev, const struct qca_fw_config *co
 	}
 
 	bda = (struct hci_rp_read_bd_addr *)skb->data;
-	if (!bacmp(&bda->bdaddr, &config->bdaddr))
+	if (!bacmp(&bda->bdaddr, &config->bdaddr)) {
 		hci_set_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY);
+		hci_set_quirk(hdev, HCI_QUIRK_USE_BDADDR_NVMEM);
+		hci_set_quirk(hdev, HCI_QUIRK_BDADDR_NVMEM_BE);
+	}
 
 	kfree_skb(skb);
 

-- 
2.34.1

[PATCH v8 9/9] arm64: dts: qcom: arduino-imola: Describe NVMEM layout for WiFi/BT addresses

[Loic Poulain]

On Arduino Uno-Q, the eMMC boot1 partition is factory provisioned
with device-specific information such as the WiFi MAC address
and the Bluetooth BD address. This partition can serve as an
alternative to additional non-volatile memory, such as a
dedicated EEPROM.

The eMMC boot partitions are typically good candidates, as they
are relatively small, read-only by default (and can be enforced
as hardware read-only), and are not affected by board reflashing
procedures, which generally target the eMMC user or GP partitions.

Describe the corresponding nvmem-layout for the WiFi and Bluetooth
addresses, and point the WiFi and Bluetooth nodes to the appropriate
NVMEM cells to retrieve them.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts | 32 ++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts b/arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts
index bf088fa9807f040f0c8f405f9111b01790b09377..38839b8a361e76f6c1989924b16095b9d8815f66 100644
--- a/arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts
+++ b/arch/arm64/boot/dts/qcom/qrb2210-arduino-imola.dts
@@ -409,7 +409,33 @@ &sdhc_1 {
 	no-sdio;
 	no-sd;
 
+	#address-cells = <1>;
+	#size-cells = <0>;
+
 	status = "okay";
+
+	card@0 {
+		compatible = "mmc-card";
+		reg = <0>;
+
+		partitions-boot1 {
+			compatible = "fixed-layout";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			wifi_mac_addr: mac-addr@4400 {
+				compatible = "mac-base";
+				reg = <0x4400 0x6>;
+				#nvmem-cell-cells = <1>;
+			};
+
+			bd_addr: bd-addr@5400 {
+				compatible = "mac-base";
+				reg = <0x5400 0x6>;
+				#nvmem-cell-cells = <1>;
+			};
+		};
+	};
 };
 
 &spi5 {
@@ -512,6 +538,9 @@ bluetooth {
 		vddch0-supply = <&pm4125_l22>;
 		enable-gpios = <&tlmm 87 GPIO_ACTIVE_HIGH>;
 		max-speed = <3000000>;
+
+		nvmem-cells = <&bd_addr 0>;
+		nvmem-cell-names = "local-bd-address";
 	};
 };
 
@@ -557,6 +586,9 @@ &wifi {
 	qcom,ath10k-calibration-variant = "ArduinoImola";
 	firmware-name = "qcm2290";
 
+	nvmem-cells = <&wifi_mac_addr 0>;
+	nvmem-cell-names = "mac-address";
+
 	status = "okay";
 };
 

-- 
2.34.1