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

Loic Poulain
2026-04-28T14:23:33Z

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.

Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>
---
include/net/bluetooth/hci.h | 18 +++++++++++++++
net/bluetooth/hci_sync.c | 56 ++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 73 insertions(+), 1 deletion(-)

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..f87cb6ae85c3a5754fe79f415ba05dd177f75fad 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -6,6 +6,7 @@
* Copyright 2023 NXP
*/

+#include <linux/nvmem-consumer.h>
#include <linux/property.h>

#include <net/bluetooth/bluetooth.h>
@@ -3588,6 +3589,54 @@ 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.
+ *
+ * All-zero BD addresses are rejected (unprovisioned).
+ */
+static int hci_dev_get_bd_addr_from_nvmem(struct hci_dev *hdev)
+{
+ struct device *dev = hdev->dev.parent;
+ struct nvmem_cell *cell;
+ const void *ba;
+ int err = 0;
+ size_t len;
+
+ cell = nvmem_cell_get(dev, "local-bd-address");
+ if (IS_ERR(cell))
+ return PTR_ERR(cell);
+
+ ba = nvmem_cell_read(cell, &len);
+ nvmem_cell_put(cell);
+
+ if (IS_ERR(ba)) {
+ bt_dev_warn(hdev, "Error reading BD address from NVMEM (%ld)\n",
+ PTR_ERR(ba));
+ err = PTR_ERR(ba);
+ goto done;
+ }
+
+ if (len != sizeof(bdaddr_t) || !bacmp(ba, BDADDR_ANY)) {
+ bt_dev_warn(hdev, "NVMEM BD address has incorrect format\n");
+ err = -EINVAL;
+ goto done;
+ }
+
+ 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);
+
+done:
+ kfree(ba);
+ return err;
+}
+
/**
* hci_dev_get_bd_addr_from_property - Get the Bluetooth Device Address
* (BD_ADDR) for a HCI device from
@@ -5042,12 +5091,17 @@ 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);

--
2.34.1