[RFC 1/4] Add usb_get_address and usb_set_address support

[<Charles.Hyde@dellteam.com>]

The core USB driver message.c is missing get/set address functionality
that stops ifconfig from being able to push MAC addresses out to USB
based ethernet devices.  Without this functionality, some USB devices
stop responding to ethernet packets when using ifconfig to change MAC
addresses.  This has been tested with a Dell Universal Dock D6000.

Signed-off-by: Charles Hyde <charles.hyde@dellteam.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
---
 drivers/usb/core/message.c | 59 ++++++++++++++++++++++++++++++++++++++
 include/linux/usb.h        |  3 ++
 2 files changed, 62 insertions(+)

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 5adf489428aa..eea775234b09 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1085,6 +1085,65 @@ int usb_clear_halt(struct usb_device *dev, int pipe)
 }
 EXPORT_SYMBOL_GPL(usb_clear_halt);
 
+/**
+ * usb_get_address - 
+ * @dev: device whose endpoint is halted
+ * @mac: buffer for containing 
+ * Context: !in_interrupt ()
+ *
+ * This will attempt to get the six byte MAC address from a USB device's
+ * ethernet controller using GET_NET_ADDRESS command.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Return: Zero on success, or else the status code returned by the
+ * underlying usb_control_msg() call.
+ */
+int usb_get_address(struct usb_device *dev, unsigned char * mac)
+{
+	int ret = -ENOMEM;
+	unsigned char *tbuf = kmalloc(256, GFP_NOIO);
+
+	if (!tbuf)
+		return -ENOMEM;
+
+	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			USB_CDC_GET_NET_ADDRESS,
+			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			0, USB_REQ_SET_ADDRESS, tbuf, 256,
+			USB_CTRL_GET_TIMEOUT);
+	if (ret == 6)
+		memcpy(mac, tbuf, 6);
+
+	kfree(tbuf);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_get_address);
+
+/**
+ * usb_set_address - 
+ * @dev: device whose endpoint is halted
+ * @mac: desired MAC address in network address order
+ * Context: !in_interrupt ()
+ *
+ * This will attempt to set a six byte MAC address to the USB device's ethernet
+ * controller using SET_NET_ADDRESS command.
+ *
+ * This call is synchronous, and may not be used in an interrupt context.
+ *
+ * Return: Zero on success, or else the status code returned by the
+ * underlying usb_control_msg() call.
+ */
+int usb_set_address(struct usb_device *dev, unsigned char *mac)
+{
+	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+			USB_CDC_SET_NET_ADDRESS,
+			USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			0, USB_REQ_SET_ADDRESS, mac, 6,
+			USB_CTRL_SET_TIMEOUT);
+}
+EXPORT_SYMBOL_GPL(usb_set_address);
+
 static int create_intf_ep_devs(struct usb_interface *intf)
 {
 	struct usb_device *udev = interface_to_usbdev(intf);
diff --git a/include/linux/usb.h b/include/linux/usb.h
index e87826e23d59..862c979d9821 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1806,6 +1806,9 @@ static inline int usb_get_ptm_status(struct usb_device *dev, void *data)
 extern int usb_string(struct usb_device *dev, int index,
 	char *buf, size_t size);
 
+extern int usb_get_address(struct usb_device *dev, unsigned char * mac);
+extern int usb_set_address(struct usb_device *dev, unsigned char * mac);
+
 /* wrappers that also update important state inside usbcore */
 extern int usb_clear_halt(struct usb_device *dev, int pipe);
 extern int usb_reset_configuration(struct usb_device *dev);
-- 
2.20.1