From a63255ff23043196fce74f143a6ebc79184fcdf2 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Thu, 30 May 2013 19:23:25 +0200
Subject: [PATCH] add code for getting the primary interface

---
 main.c   | 27 +++++++++++++++++++++++++++
 switch.h |  2 ++
 2 files changed, 29 insertions(+)

diff --git a/main.c b/main.c
index 5f5c4ff..cf58c17 100644
--- a/main.c
+++ b/main.c
@@ -187,6 +187,27 @@ find_dev_data(struct usbdev_data *data, struct device *dev)
 	return NULL;
 }
 
+static void
+parse_interface_config(libusb_device *dev, struct usbdev_data *data)
+{
+	struct libusb_config_descriptor *config;
+	const struct libusb_interface *iface;
+
+	data->interface = -1;
+	if (libusb_get_config_descriptor(dev, 0, &config))
+		return;
+
+	data->config = config;
+	if (!config->bNumInterfaces)
+		return;
+
+	iface = &config->interface[0];
+	if (!iface->num_altsetting)
+		return;
+
+	data->interface = iface->altsetting[0].bInterfaceNumber;
+}
+
 static void iterate_devs(cmd_cb_t cb)
 {
 	struct usbdev_data data;
@@ -221,9 +242,15 @@ static void iterate_devs(cmd_cb_t cb)
 			data.devh, data.desc.iSerialNumber,
 			(void *) data.serial, sizeof(data.serial));
 
+		parse_interface_config(usbdevs[i], &data);
+
 		data.info = find_dev_data(&data, dev);
 		if (data.info)
 			cb(&data);
+
+		if (data.config)
+			libusb_free_config_descriptor(data.config);
+
 		libusb_close(data.devh);
 	}
 }
diff --git a/switch.h b/switch.h
index eda94c2..a6d5297 100644
--- a/switch.h
+++ b/switch.h
@@ -6,8 +6,10 @@
 
 struct usbdev_data {
 	struct libusb_device_descriptor desc;
+	struct libusb_config_descriptor *config;
 	libusb_device_handle *devh;
 	struct blob_attr *info;
+	int interface;
 
 	char idstr[10];
 	char mfg[128], prod[128], serial[128];
-- 
2.30.2