CDC-NCM: add support for Apple's private interface

Available on iOS/iPadOS >= 17, where this new interface is used by
developer tools using the new RemoteXPC protocol.

This private interface lacks a status endpoint, presumably because there
isn't a physical cable that can be unplugged, nor any speed changes to
be notified about.

Note that NCM interfaces are not exposed until a mode switch is
requested, which macOS does automatically.

The mode switch can be performed like this:

uint8_t status;
libusb_control_transfer(device_handle,
LIBUSB_RECIPIENT_DEVICE | LIBUSB_REQUEST_TYPE_VENDOR |
LIBUSB_ENDPOINT_IN,
82, /* bRequest */
0, /* wValue */
3, /* wIndex */
&status,
sizeof(status),
0);

Newer versions of usbmuxd do this automatically.

Co-developed-by: Håvard Sørbø <[e-mail]>
Signed-off-by: Håvard Sørbø <[e-mail]>
Signed-off-by: Ole André Vadla Ravnås <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/usb/cdc_ncm.c

···
 
 	cdc_ncm_find_endpoints(dev, ctx->data);
 	cdc_ncm_find_endpoints(dev, ctx->control);
-	if (!dev->in || !dev->out || !dev->status) {
+	if (!dev->in || !dev->out ||
+	    (!dev->status && dev->driver_info->flags & FLAG_LINK_INTR)) {
 		dev_dbg(&intf->dev, "failed to collect endpoints\n");
 		goto error2;
 	}
···
 	.set_rx_mode = usbnet_cdc_update_filter,
 };
 
+/* Same as cdc_ncm_info, but with FLAG_SEND_ZLP */
+static const struct driver_info apple_tethering_interface_info = {
+	.description = "CDC NCM (Apple Tethering)",
+	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
+			| FLAG_LINK_INTR | FLAG_ETHER | FLAG_SEND_ZLP,
+	.bind = cdc_ncm_bind,
+	.unbind = cdc_ncm_unbind,
+	.manage_power = usbnet_manage_power,
+	.status = cdc_ncm_status,
+	.rx_fixup = cdc_ncm_rx_fixup,
+	.tx_fixup = cdc_ncm_tx_fixup,
+	.set_rx_mode = usbnet_cdc_update_filter,
+};
+
+/* Same as apple_tethering_interface_info, but without FLAG_LINK_INTR */
+static const struct driver_info apple_private_interface_info = {
+	.description = "CDC NCM (Apple Private)",
+	.flags = FLAG_POINTTOPOINT | FLAG_NO_SETINT | FLAG_MULTI_PACKET
+			| FLAG_ETHER | FLAG_SEND_ZLP,
+	.bind = cdc_ncm_bind,
+	.unbind = cdc_ncm_unbind,
+	.manage_power = usbnet_manage_power,
+	.status = cdc_ncm_status,
+	.rx_fixup = cdc_ncm_rx_fixup,
+	.tx_fixup = cdc_ncm_tx_fixup,
+	.set_rx_mode = usbnet_cdc_update_filter,
+};
+
 /* Same as cdc_ncm_info, but with FLAG_WWAN */
 static const struct driver_info wwan_info = {
 	.description = "Mobile Broadband Network Device",
···
 };
 
 static const struct usb_device_id cdc_devs[] = {
+	/* iPhone */
+	{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x12a8, 2),
+		.driver_info = (unsigned long)&apple_tethering_interface_info,
+	},
+	{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x12a8, 4),
+		.driver_info = (unsigned long)&apple_private_interface_info,
+	},
+
+	/* iPad */
+	{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x12ab, 2),
+		.driver_info = (unsigned long)&apple_tethering_interface_info,
+	},
+	{ USB_DEVICE_INTERFACE_NUMBER(0x05ac, 0x12ab, 4),
+		.driver_info = (unsigned long)&apple_private_interface_info,
+	},
+
 	/* Ericsson MBM devices like F5521gw */
 	{ .match_flags = USB_DEVICE_ID_MATCH_INT_INFO
 		| USB_DEVICE_ID_MATCH_VENDOR,