net: cdc_ncm: add Huawei devices

A number of Huawei 3G and LTE modems implement a CDC NCM function,
including the necessary functional descriptors, but using a non
standard interface layout and class/subclass/protocol codes.

These devices can be handled by this driver with only a minor
change to the probing logic, allowing a single combined control
and data interface. This works because the devices
- include a CDC Union descriptor labelling the combined
interface as both master and slave, and
- have an alternate setting #1 for the bulk endpoints on the
combined interface.

The 3G/LTE network connection is managed by vendor specific AT
commands on a serial function in the same composite device.
Handling the managment function is out of the scope of this
driver. It will be handled by an appropriate USB serial
driver.

Reported-and-Tested-by: Olof Ermis <[e-mail]>
Reported-and-Tested-by: Tommy Cheng <[e-mail]>
Signed-off-by: Bjørn Mork <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/usb/cdc_ncm.c

···
 	    (ctx->ether_desc == NULL) || (ctx->control != intf))
 		goto error;
 
-	/* claim interfaces, if any */
-	temp = usb_driver_claim_interface(driver, ctx->data, dev);
-	if (temp)
-		goto error;
+	/* claim data interface, if different from control */
+	if (ctx->data != ctx->control) {
+		temp = usb_driver_claim_interface(driver, ctx->data, dev);
+		if (temp)
+			goto error;
+	}
 
 	iface_no = ctx->data->cur_altsetting->desc.bInterfaceNumber;
 
···
 		hrtimer_cancel(&ctx->tx_timer);
 
 	tasklet_kill(&ctx->bh);
+
+	/* handle devices with combined control and data interface */
+	if (ctx->control == ctx->data)
+		ctx->data = NULL;
 
 	/* disconnect master --> disconnect slave */
 	if (intf == ctx->control && ctx->data) {
···
 	  .bInterfaceSubClass = USB_CDC_SUBCLASS_NCM,
 	  .bInterfaceProtocol = USB_CDC_PROTO_NONE,
 	  .driver_info = (unsigned long) &wwan_info,
+	},
+
+	/* Huawei NCM devices disguised as vendor specific */
+	{ USB_VENDOR_AND_INTERFACE_INFO(0x12d1, 0xff, 0x02, 0x16),
+	  .driver_info = (unsigned long)&wwan_info,
+	},
+	{ USB_VENDOR_AND_INTERFACE_INFO(0x12d1, 0xff, 0x02, 0x46),
+	  .driver_info = (unsigned long)&wwan_info,
 	},
 
 	/* Generic CDC-NCM devices */