[PATCH v4 1/2] Bluetooth: Add device_get_bd_address()

[Matthias Kaehlcke]

Provide an API for Bluetooth drivers to retrieve the Bluetooth Device
address (BD_ADDR) for a device. If the firmware node of the device
has a property 'local-bd-address' the BD address is read from this
property.

Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
Changes in v4:
- move code from driver/base/property.c to net/bluetooth/lib.c
- undo move of bdaddr_t declaration
- merge fwnode_get_bd_address() into device_get_bd_address(). as of now
  the function is not needed, it can be created later if necessary
- minor improvements suggested by Sakari
- updated commit message
- added 'Reviewed-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>' tag

Changes in v3:
- move definition of bdaddr_t to types.h to avoid include of
  bluetooth.h from property.h
- add stubs for the new functions

Changes in v2:
- use bdaddr_t instead of byte pointer + len
- use EXPORT_SYMBOL_GPL for the new functions instead of EXPORT_SYMBOL
- put new functions inside #if IS_ENABLED(CONFIG_BT)
- some new line juggling in property.h
- added 'Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>' tag
---
 include/net/bluetooth/bluetooth.h |  2 ++
 net/bluetooth/lib.c               | 34 +++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index ec9d6bc65855..6c4cecfda816 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -413,4 +413,6 @@ void mgmt_exit(void);
 
 void bt_sock_reclassify_lock(struct sock *sk, int proto);
 
+int device_get_bd_address(struct device *dev, bdaddr_t *bd_addr);
+
 #endif /* __BLUETOOTH_H */
diff --git a/net/bluetooth/lib.c b/net/bluetooth/lib.c
index 63e65d9b4b24..78a58ea586c6 100644
--- a/net/bluetooth/lib.c
+++ b/net/bluetooth/lib.c
@@ -26,7 +26,10 @@
 
 #define pr_fmt(fmt) "Bluetooth: " fmt
 
+#include <linux/etherdevice.h>
 #include <linux/export.h>
+#include <linux/fwnode.h>
+#include <linux/property.h>
 
 #include <net/bluetooth/bluetooth.h>
 
@@ -198,3 +201,34 @@ void bt_err_ratelimited(const char *format, ...)
 	va_end(args);
 }
 EXPORT_SYMBOL(bt_err_ratelimited);
+
+/**
+ * device_get_bd_address - Get the Bluetooth Device Address (BD_ADDR) for a
+ *                         given device
+ * @dev:	Pointer to the device
+ * @bd_addr:	Pointer to struct to store the BD address in
+ *
+ * Search the firmware node of the device for 'local-bd-address'.
+ *
+ * All-zero BD addresses are rejected, because those could be properties
+ * that exist in the firmware tables, but were not updated by the firmware. For
+ * example, the DTS could define 'local-bd-address', with zero BD addresses.
+ */
+int device_get_bd_address(struct device *dev, bdaddr_t *bd_addr)
+{
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
+	bdaddr_t ba;
+	int ret;
+
+	ret = fwnode_property_read_u8_array(fwnode, "local-bd-address",
+					    (u8 *)&ba, sizeof(ba));
+	if (ret < 0)
+		return ret;
+	if (is_zero_ether_addr((u8 *)&ba))
+		return -ENODATA;
+
+	*bd_addr = ba;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(device_get_bd_address);
-- 
2.19.0.605.g01d371f741-goog