[RFC 3/3] net: cdc_ncm: Add ACPI MAC address pass through functionality

[<Charles.Hyde@xxxxxxxxxxxx>]

This change adds support to cdc_ncm for ACPI MAC address pass through
functionality that also exists in the Realtek r8152 driver.  This is in
support of Dell's Universal Dock D6000, to give it the same feature
capability as is currently available in Windows and advertized on Dell's
product web site.

Signed-off-by: Charles Hyde <charles.hyde@xxxxxxxxxxxx>
Cc: Mario Limonciello <mario.limonciello@xxxxxxxx>
Cc: Oliver Neukum <oliver@xxxxxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
---
 drivers/net/usb/cdc_ncm.c | 47 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 6fbe88fd7896..6f138ec3f362 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -52,6 +52,7 @@
 #include <linux/usb/usbnet.h>
 #include <linux/usb/cdc.h>
 #include <linux/usb/cdc_ncm.h>
+#include <acpi/acpi_mac_passthru.h>
 
 #if IS_ENABLED(CONFIG_USB_NET_CDC_MBIM)
 static bool prefer_mbim = true;
@@ -984,11 +985,20 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
 	usb_set_intfdata(ctx->control, dev);
 
 	if (ctx->ether_desc) {
-		temp = usbnet_get_ethernet_addr(dev, ctx->ether_desc->iMACAddress);
+		struct sockaddr sa;
+
+		temp = cdc_ncm_get_ethernet_address(dev, ctx);
 		if (temp) {
 			dev_dbg(&intf->dev, "failed to get mac address\n");
 			goto error2;
 		}
+		if (get_acpi_mac_passthru(&intf->dev, &sa) == 0) {
+			if (memcmp(dev->net->dev_addr, sa.sa_data, ETH_ALEN) != 0) {
+				if (cdc_ncm_set_ethernet_address(dev, &sa) == 0) {
+					memcpy(dev->net->dev_addr, sa.sa_data, ETH_ALEN);
+				}
+			}
+		}
 		dev_info(&intf->dev, "MAC-Address: %pM\n", dev->net->dev_addr);
 	}
 
@@ -1716,6 +1726,37 @@ static void cdc_ncm_status(struct usbnet *dev, struct urb *urb)
 	}
 }
 
+static int cdc_ncm_resume (struct usb_interface *intf)
+{
+	struct usbnet *dev = usb_get_intfdata(intf);
+	struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
+	int ret;
+
+	ret = usbnet_resume(intf);
+	if (ret != 0)
+		goto error2;
+
+	if (ctx->ether_desc) {
+		struct sockaddr sa;
+
+		if (cdc_ncm_get_ethernet_address(dev, ctx)) {
+			dev_dbg(&intf->dev, "failed to get mac address\n");
+			goto error2;
+		}
+		if (get_acpi_mac_passthru(&intf->dev, &sa) == 0) {
+			if (memcmp(dev->net->dev_addr, sa.sa_data, ETH_ALEN) != 0) {
+				if (cdc_ncm_set_ethernet_address(dev, &sa) == 0) {
+					memcpy(dev->net->dev_addr, sa.sa_data, ETH_ALEN);
+				}
+			}
+		}
+		dev_info(&intf->dev, "MAC-Address: %pM\n", dev->net->dev_addr);
+	}
+
+error2:
+	return ret;
+}
+
 static const struct driver_info cdc_ncm_info = {
 	.description = "CDC NCM",
 	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
@@ -1848,8 +1889,8 @@ static struct usb_driver cdc_ncm_driver = {
 	.probe = usbnet_probe,
 	.disconnect = usbnet_disconnect,
 	.suspend = usbnet_suspend,
-	.resume = usbnet_resume,
-	.reset_resume =	usbnet_resume,
+	.resume = cdc_ncm_resume,
+	.reset_resume =	cdc_ncm_resume,
 	.supports_autosuspend = 1,
 	.disable_hub_initiated_lpm = 1,
 };
-- 
2.20.1