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From:   Matthias Kaehlcke <mka@chromium.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Marcin Wojtas <mw@semihalf.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Sinan Kaya <okaya@codeaurora.org>,
        Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>
Cc:     linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        Balakrishna Godavarthi <bgodavar@codeaurora.org>,
        Loic Poulain <loic.poulain@linaro.org>,
        Brian Norris <briannorris@chromium.org>,
        Matthias Kaehlcke <mka@chromium.org>
Subject: [PATCH 1/2] device property: Add device_get_bd_address() and fwnode_get_bd_address()
Date:   Thu, 20 Sep 2018 15:34:35 -0700
Message-Id: <20180920223436.202454-2-mka@chromium.org>
In-Reply-To: <20180920223436.202454-1-mka@chromium.org>
References: <20180920223436.202454-1-mka@chromium.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Provide an API for Bluetooth drivers to retrieve the Bluetooth Device
address (BD_ADDR) for a device. If the device node has a property
'local-bd-address' the BD address is read from this property.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
 drivers/base/property.c  | 49 ++++++++++++++++++++++++++++++++++++++++
 include/linux/property.h |  4 ++++
 2 files changed, 53 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 240ab5230ff6..8fe546b9805a 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -18,6 +18,8 @@
 #include <linux/etherdevice.h>
 #include <linux/phy.h>
 
+#define BD_ADDR_LEN	6
+
 struct property_set {
 	struct device *dev;
 	struct fwnode_handle fwnode;
@@ -1315,6 +1317,53 @@ void *device_get_mac_address(struct device *dev, char *addr, int alen)
 }
 EXPORT_SYMBOL(device_get_mac_address);
 
+/**
+ * fwnode_get_bd_address - Get the Bluetooth Device Address (BD_ADDR) from the
+ *                         firmware node
+ * @fwnode:	Pointer to the firmware node
+ * @addr:	Address of buffer to store the BD address in
+ * @alen:	Length of the buffer pointed to by addr, should be BD_ADDR_LEN
+ *
+ * Search the firmware node 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 fwnode_get_bd_address(struct fwnode_handle *fwnode, u8 *addr, int alen)
+{
+	u8 buf[BD_ADDR_LEN];
+	int ret;
+
+	if (alen != BD_ADDR_LEN)
+		return -EINVAL;
+
+	ret = fwnode_property_read_u8_array(fwnode, "local-bd-address",
+					    buf, alen);
+	if (ret < 0)
+		return ret;
+	if (is_zero_ether_addr(buf))
+		return -ENODATA;
+
+	memcpy(addr, buf, BD_ADDR_LEN);
+
+	return 0;
+}
+EXPORT_SYMBOL(fwnode_get_bd_address);
+
+/**
+ * device_get_bd_address - Get the Bluetooth Device Address (BD_ADDR) for a
+ *                         given device
+ * @dev:	Pointer to the device
+ * @addr:	Address of buffer to store the BD address in
+ * @alen:	Length of the buffer pointed to by addr, should be BD_ADDR_LEN
+ */
+int device_get_bd_address(struct device *dev, u8 *addr, int alen)
+{
+	return fwnode_get_bd_address(dev_fwnode(dev), addr, alen);
+}
+EXPORT_SYMBOL(device_get_bd_address);
+
 /**
  * fwnode_irq_get - Get IRQ directly from a fwnode
  * @fwnode:	Pointer to the firmware node
diff --git a/include/linux/property.h b/include/linux/property.h
index ac8a1ebc4c1b..4e2f1b276f4f 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -287,9 +287,13 @@ int device_get_phy_mode(struct device *dev);
 
 void *device_get_mac_address(struct device *dev, char *addr, int alen);
 
+int device_get_bd_address(struct device *dev, u8 *addr, int alen);
+
 int fwnode_get_phy_mode(struct fwnode_handle *fwnode);
 void *fwnode_get_mac_address(struct fwnode_handle *fwnode,
 			     char *addr, int alen);
+int fwnode_get_bd_address(struct fwnode_handle *fwnode,
+			  u8 *addr, int alen);
 struct fwnode_handle *fwnode_graph_get_next_endpoint(
 	const struct fwnode_handle *fwnode, struct fwnode_handle *prev);
 struct fwnode_handle *
-- 
2.19.0.444.g18242da7ef-goog