[PATCH v3 3/3] net: cdc_ncm: Add ACPI MAC address pass through functionality

[Charles Hyde <chip.programmer@gmail.com>]

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.

Today's v3 patch series includes a function named get_ethernet_addr()
which replaces two instances where the same code snippet was located in
teh previous patch series.  I also created a post reset function to set
the MAC address, if there exists an ACPI MAC address pass through (MAPT)
method.  Oliver Neukum had requested a post reset function for this
purpose.

Signed-off-by: Charles Hyde <charles.hyde@dellteam.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Cc: chip.programmer@gmail.com
Cc: Oliver Neukum <oliver@neukum.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
---
 drivers/net/usb/cdc_ncm.c | 74 +++++++++++++++++++++++++++++++++------
 1 file changed, 64 insertions(+), 10 deletions(-)

diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 85093579612f..e0152d44f5af 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;
@@ -833,6 +834,45 @@ static const struct net_device_ops cdc_ncm_netdev_ops = {
 	.ndo_validate_addr   = eth_validate_addr,
 };
 
+static int get_ethernet_addr(struct usb_interface *intf)
+{
+	struct sockaddr sa;
+	struct usbnet *dev = usb_get_intfdata(intf);
+	struct cdc_ncm_ctx *ctx;
+	int ret = 0;
+
+	if (!dev)
+		return 0;
+
+	ctx = (struct cdc_ncm_ctx *)dev->data[0];
+	if (!ctx->ether_desc)
+		return 0;
+
+	ret = cdc_ncm_get_ethernet_address(dev, ctx);
+	if (ret) {
+		dev_dbg(&intf->dev, "failed to get mac address\n");
+		return ret;
+	}
+
+	/* Check for a Dell Universal Dock D6000 before checking if ACPI
+	 * supports MAC address pass through.
+	 */
+	if (strstr(dev->udev->product, "D6000")) {
+		sa.sa_family = dev->net->type;
+		if (get_acpi_mac_passthru(sa.sa_data)) {
+			if (!memcmp(dev->net->dev_addr, sa.sa_data,
+				    ETH_ALEN)) {
+				if (!cdc_ncm_set_ethernet_address(dev, &sa))
+					memcpy(dev->net->dev_addr, sa.sa_data,
+					       ETH_ALEN);
+			}
+		}
+	}
+	dev_info(&intf->dev, "MAC-Address: %pM\n", dev->net->dev_addr);
+
+	return 0;
+}
+
 int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_altsetting, int drvflags)
 {
 	struct cdc_ncm_ctx *ctx;
@@ -983,14 +1023,8 @@ int cdc_ncm_bind_common(struct usbnet *dev, struct usb_interface *intf, u8 data_
 	usb_set_intfdata(ctx->data, dev);
 	usb_set_intfdata(ctx->control, dev);
 
-	if (ctx->ether_desc) {
-		temp = usbnet_get_ethernet_addr(dev, ctx->ether_desc->iMACAddress);
-		if (temp) {
-			dev_dbg(&intf->dev, "failed to get mac address\n");
-			goto error2;
-		}
-		dev_info(&intf->dev, "MAC-Address: %pM\n", dev->net->dev_addr);
-	}
+	if (get_ethernet_addr(intf))
+		goto error2;
 
 	/* finish setting up the device specific data */
 	cdc_ncm_setup(dev);
@@ -1716,6 +1750,25 @@ static void cdc_ncm_status(struct usbnet *dev, struct urb *urb)
 	}
 }
 
+static int cdc_ncm_resume(struct usb_interface *intf)
+{
+	int ret;
+
+	ret = usbnet_resume(intf);
+	if (ret == 0)
+		get_ethernet_addr(intf);
+
+	return ret;
+}
+
+static int cdc_ncm_post_reset(struct usb_interface *intf)
+{
+	/* reset the MAC address in case of policy change */
+	get_ethernet_addr(intf);
+
+	return 0;
+}
+
 static const struct driver_info cdc_ncm_info = {
 	.description = "CDC NCM",
 	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
@@ -1848,8 +1901,9 @@ 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,
+	.post_reset = cdc_ncm_post_reset,
 	.supports_autosuspend = 1,
 	.disable_hub_initiated_lpm = 1,
 };
-- 
2.20.1