Subject: [RFC 2/4] Allow cdc_ncm to set MAC address in hardware

From: <[email-masked]>
Date: Tue, 20 Aug 2019 22:21:03 +0000

This patch adds support for pushing a MAC address out to USB based
ethernet controllers driven by cdc_ncm.  With this change, ifconfig can
now set the device's MAC address.  For example, the Dell Universal Dock
D6000 is driven by cdc_ncm.  The D6000 can now have its MAC address set
by ifconfig, as it can be done in Windows.  This was tested with a D6000
using ifconfig.

Signed-off-by: Charles Hyde <[email-masked]>
Cc: Mario Limonciello <[email-masked]>
Cc: Oliver Neukum <[email-masked]>
Cc: [email-masked]
Cc: [email-masked]
---
 drivers/net/usb/cdc_ncm.c  | 20 +++++++++++++++++++-
 drivers/net/usb/usbnet.c   | 37 ++++++++++++++++++++++++++++---------
 include/linux/usb/usbnet.h |  1 +
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 50c05d0f44cb..f77c8672f972 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -750,6 +750,24 @@ int cdc_ncm_change_mtu(struct net_device *net, int new_mtu)
 }
 EXPORT_SYMBOL_GPL(cdc_ncm_change_mtu);
 
+/* Provide method to push MAC address to the USB device's ethernet controller.
+ */
+int cdc_ncm_set_mac_addr(struct net_device *net, void *p)
+{
+	struct usbnet *dev = netdev_priv(net);
+	struct sockaddr *addr = p;
+
+	memcpy(dev->net->dev_addr, addr->sa_data, ETH_ALEN);
+	/*
+	 * Try to push the MAC address out to the device.  Ignore any errors,
+	 * to be compatible with prior versions of this source.
+	 */
+	usbnet_set_ethernet_addr(dev);
+
+	return eth_mac_addr(net, p);
+}
+EXPORT_SYMBOL_GPL(cdc_ncm_set_mac_addr);
+
 static const struct net_device_ops cdc_ncm_netdev_ops = {
 	.ndo_open	     = usbnet_open,
 	.ndo_stop	     = usbnet_stop,
@@ -757,7 +775,7 @@ static const struct net_device_ops cdc_ncm_netdev_ops = {
 	.ndo_tx_timeout	     = usbnet_tx_timeout,
 	.ndo_get_stats64     = usbnet_get_stats64,
 	.ndo_change_mtu	     = cdc_ncm_change_mtu,
-	.ndo_set_mac_address = eth_mac_addr,
+	.ndo_set_mac_address = cdc_ncm_set_mac_addr,
 	.ndo_validate_addr   = eth_validate_addr,
 };
 
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 72514c46b478..72bdac34b0ee 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -149,20 +149,39 @@ int usbnet_get_ethernet_addr(struct usbnet *dev, int iMACAddress)
 	int 		tmp = -1, ret;
 	unsigned char	buf [13];
 
-	ret = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
-	if (ret == 12)
-		tmp = hex2bin(dev->net->dev_addr, buf, 6);
-	if (tmp < 0) {
-		dev_dbg(&dev->udev->dev,
-			"bad MAC string %d fetch, %d\n", iMACAddress, tmp);
-		if (ret >= 0)
-			ret = -EINVAL;
-		return ret;
+	ret = usb_get_address(dev->udev, buf);
+	if (ret == 6)
+		memcpy(dev->net->dev_addr, buf, 6);
+	else if (ret < 0) {
+		ret = usb_string(dev->udev, iMACAddress, buf, sizeof buf);
+		if (ret == 12)
+			tmp = hex2bin(dev->net->dev_addr, buf, 6);
+		if (tmp < 0) {
+			dev_dbg(&dev->udev->dev,
+				"bad MAC string %d fetch, %d\n", iMACAddress,
+				tmp);
+			if (ret >= 0)
+				ret = -EINVAL;
+			return ret;
+		}
 	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(usbnet_get_ethernet_addr);
 
+int usbnet_set_ethernet_addr(struct usbnet *dev)
+{
+	int ret;
+
+	ret = usb_set_address(dev->udev, dev->net->dev_addr);
+	if (ret < 0) {
+		dev_dbg(&dev->udev->dev,
+			"bad MAC address put, %d\n", ret);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usbnet_set_ethernet_addr);
+
 static void intr_complete (struct urb *urb)
 {
 	struct usbnet	*dev = urb->context;
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index d8860f2d0976..f2b2c5ab5493 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -258,6 +258,7 @@ extern int usbnet_change_mtu(struct net_device *net, int new_mtu);
 
 extern int usbnet_get_endpoints(struct usbnet *, struct usb_interface *);
 extern int usbnet_get_ethernet_addr(struct usbnet *, int);
+extern int usbnet_set_ethernet_addr(struct usbnet *);
 extern void usbnet_defer_kevent(struct usbnet *, int);
 extern void usbnet_skb_return(struct usbnet *, struct sk_buff *);
 extern void usbnet_unlink_rx_urbs(struct usbnet *);
-- 
2.20.1