[PATCH RFC 3/5] Bluetooth: hci_qca: Support BD address from an nvmem cell

[Abel Vesa]

Read an optional Bluetooth device address from an nvmem cell named
"bd-address" (as already supported by hci_ll), and program it into the
controller during setup. This lets QCA controllers source their BD_ADDR
from firmware-provisioned storage such as a UEFI variable exposed via
nvmem. An all-zero value is ignored, so unprovisioned storage leaves
the controller default address untouched.

Assisted-by: LLM
Signed-off-by: Abel Vesa <abel.vesa at oss.qualcomm.com>
---
 drivers/bluetooth/hci_qca.c | 48 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 7089e9b639b2..b704f4c3e1a4 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -25,6 +25,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/acpi.h>
 #include <linux/platform_device.h>
 #include <linux/pwrseq/consumer.h>
@@ -230,6 +231,8 @@ struct qca_serdev {
 	bool bdaddr_property_broken;
 	bool support_hfp_hw_offload;
 	const char *firmware_name[2];
+	bdaddr_t bdaddr;
+	bool bdaddr_valid;
 };
 
 static int qca_regulator_enable(struct qca_serdev *qcadev);
@@ -2079,6 +2082,16 @@ static int qca_setup(struct hci_uart *hu)
 	else
 		hu->hdev->set_bdaddr = qca_set_bdaddr;
 
+	/* Program a BD address sourced from an nvmem cell, if provided. */
+	if (qcadev && qcadev->bdaddr_valid) {
+		int berr = hu->hdev->set_bdaddr(hdev, &qcadev->bdaddr);
+
+		if (berr)
+			bt_dev_warn(hdev, "Failed to set nvmem bd-address: %d", berr);
+		else
+			bt_dev_info(hdev, "Set bd-address %pMR from nvmem", &qcadev->bdaddr);
+	}
+
 	if (qcadev && qcadev->support_hfp_hw_offload)
 		qca_configure_hfp_offload(hdev);
 
@@ -2420,6 +2433,41 @@ static int qca_serdev_probe(struct serdev_device *serdev)
 	qcadev->bdaddr_property_broken = device_property_read_bool(&serdev->dev,
 			"qcom,local-bd-address-broken");
 
+	/* Optional BD address from an nvmem cell (e.g. a UEFI variable). */
+	{
+		struct nvmem_cell *cell;
+
+		cell = nvmem_cell_get(&serdev->dev, "bd-address");
+		if (IS_ERR(cell)) {
+			err = PTR_ERR(cell);
+			if (err == -EPROBE_DEFER)
+				return err;
+			/* -ENOENT/-ENOSYS: no cell configured, ignore. */
+		} else {
+			size_t clen;
+			void *cdata = nvmem_cell_read(cell, &clen);
+
+			nvmem_cell_put(cell);
+			if (!IS_ERR(cdata)) {
+				/*
+				 * Ignore an all-zero address: the backing
+				 * storage has not been provisioned.
+				 */
+				if (clen == sizeof(bdaddr_t) &&
+				    bacmp(cdata, BDADDR_ANY)) {
+					/*
+					 * Per the device tree bindings the nvmem
+					 * value is MSB first, while bdaddr_t is
+					 * LSB first.
+					 */
+					baswap(&qcadev->bdaddr, cdata);
+					qcadev->bdaddr_valid = true;
+				}
+				kfree(cdata);
+			}
+		}
+	}
+
 	if (data)
 		qcadev->btsoc_type = data->soc_type;
 	else

-- 
2.54.0