USB gadget: video class function driver

This USB video class function driver implements a video capture device from the
host's point of view. It creates a V4L2 output device on the gadget's side to
transfer data from a userspace application over USB.

The UVC-specific descriptors are passed by the gadget driver to the UVC
function driver, making them completely configurable without any modification
to the function's driver code.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 661 insertions, 0 deletions

diff --git a/drivers/usb/gadget/f_uvc.c b/drivers/usb/gadget/f_uvc.c
new file mode 100644
index 00000000000..fc2611f8b32
--- /dev/null
+++ b/drivers/usb/gadget/f_uvc.c
@@ -0,0 +1,661 @@
+/*
+ *	uvc_gadget.c  --  USB Video Class Gadget driver
+ *
+ *	Copyright (C) 2009-2010
+ *	    Laurent Pinchart (laurent.pinchart@ideasonboard.com)
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License as published by
+ *	the Free Software Foundation; either version 2 of the License, or
+ *	(at your option) any later version.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/video.h>
+#include <linux/vmalloc.h>
+#include <linux/wait.h>
+
+#include <media/v4l2-dev.h>
+#include <media/v4l2-event.h>
+
+#include "uvc.h"
+
+unsigned int uvc_trace_param;
+
+/* --------------------------------------------------------------------------
+ * Function descriptors
+ */
+
+/* string IDs are assigned dynamically */
+
+#define UVC_STRING_ASSOCIATION_IDX		0
+#define UVC_STRING_CONTROL_IDX			1
+#define UVC_STRING_STREAMING_IDX		2
+
+static struct usb_string uvc_en_us_strings[] = {
+	[UVC_STRING_ASSOCIATION_IDX].s = "UVC Camera",
+	[UVC_STRING_CONTROL_IDX].s = "Video Control",
+	[UVC_STRING_STREAMING_IDX].s = "Video Streaming",
+	{  }
+};
+
+static struct usb_gadget_strings uvc_stringtab = {
+	.language = 0x0409,	/* en-us */
+	.strings = uvc_en_us_strings,
+};
+
+static struct usb_gadget_strings *uvc_function_strings[] = {
+	&uvc_stringtab,
+	NULL,
+};
+
+#define UVC_INTF_VIDEO_CONTROL			0
+#define UVC_INTF_VIDEO_STREAMING		1
+
+static struct usb_interface_assoc_descriptor uvc_iad __initdata = {
+	.bLength		= USB_DT_INTERFACE_ASSOCIATION_SIZE,
+	.bDescriptorType	= USB_DT_INTERFACE_ASSOCIATION,
+	.bFirstInterface	= 0,
+	.bInterfaceCount	= 2,
+	.bFunctionClass		= USB_CLASS_VIDEO,
+	.bFunctionSubClass	= 0x03,
+	.bFunctionProtocol	= 0x00,
+	.iFunction		= 0,
+};
+
+static struct usb_interface_descriptor uvc_control_intf __initdata = {
+	.bLength		= USB_DT_INTERFACE_SIZE,
+	.bDescriptorType	= USB_DT_INTERFACE,
+	.bInterfaceNumber	= UVC_INTF_VIDEO_CONTROL,
+	.bAlternateSetting	= 0,
+	.bNumEndpoints		= 1,
+	.bInterfaceClass	= USB_CLASS_VIDEO,
+	.bInterfaceSubClass	= 0x01,
+	.bInterfaceProtocol	= 0x00,
+	.iInterface		= 0,
+};
+
+static struct usb_endpoint_descriptor uvc_control_ep __initdata = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize		= cpu_to_le16(16),
+	.bInterval		= 8,
+};
+
+static struct uvc_control_endpoint_descriptor uvc_control_cs_ep __initdata = {
+	.bLength		= UVC_DT_CONTROL_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_CS_ENDPOINT,
+	.bDescriptorSubType	= UVC_EP_INTERRUPT,
+	.wMaxTransferSize	= cpu_to_le16(16),
+};
+
+static struct usb_interface_descriptor uvc_streaming_intf_alt0 __initdata = {
+	.bLength		= USB_DT_INTERFACE_SIZE,
+	.bDescriptorType	= USB_DT_INTERFACE,
+	.bInterfaceNumber	= UVC_INTF_VIDEO_STREAMING,
+	.bAlternateSetting	= 0,
+	.bNumEndpoints		= 0,
+	.bInterfaceClass	= USB_CLASS_VIDEO,
+	.bInterfaceSubClass	= 0x02,
+	.bInterfaceProtocol	= 0x00,
+	.iInterface		= 0,
+};
+
+static struct usb_interface_descriptor uvc_streaming_intf_alt1 __initdata = {
+	.bLength		= USB_DT_INTERFACE_SIZE,
+	.bDescriptorType	= USB_DT_INTERFACE,
+	.bInterfaceNumber	= UVC_INTF_VIDEO_STREAMING,
+	.bAlternateSetting	= 1,
+	.bNumEndpoints		= 1,
+	.bInterfaceClass	= USB_CLASS_VIDEO,
+	.bInterfaceSubClass	= 0x02,
+	.bInterfaceProtocol	= 0x00,
+	.iInterface		= 0,
+};
+
+static struct usb_endpoint_descriptor uvc_streaming_ep = {
+	.bLength		= USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType	= USB_DT_ENDPOINT,
+	.bEndpointAddress	= USB_DIR_IN,
+	.bmAttributes		= USB_ENDPOINT_XFER_ISOC,
+	.wMaxPacketSize		= cpu_to_le16(512),
+	.bInterval		= 1,
+};
+
+static const struct usb_descriptor_header * const uvc_fs_streaming[] = {
+	(struct usb_descriptor_header *) &uvc_streaming_intf_alt1,
+	(struct usb_descriptor_header *) &uvc_streaming_ep,
+	NULL,
+};
+
+static const struct usb_descriptor_header * const uvc_hs_streaming[] = {
+	(struct usb_descriptor_header *) &uvc_streaming_intf_alt1,
+	(struct usb_descriptor_header *) &uvc_streaming_ep,
+	NULL,
+};
+
+/* --------------------------------------------------------------------------
+ * Control requests
+ */
+
+static void
+uvc_function_ep0_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct uvc_device *uvc = req->context;
+	struct v4l2_event v4l2_event;
+	struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
+
+	if (uvc->event_setup_out) {
+		uvc->event_setup_out = 0;
+
+		memset(&v4l2_event, 0, sizeof(v4l2_event));
+		v4l2_event.type = UVC_EVENT_DATA;
+		uvc_event->data.length = req->actual;
+		memcpy(&uvc_event->data.data, req->buf, req->actual);
+		v4l2_event_queue(uvc->vdev, &v4l2_event);
+	}
+}
+
+static int
+uvc_function_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct uvc_device *uvc = to_uvc(f);
+	struct v4l2_event v4l2_event;
+	struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
+
+	/* printk(KERN_INFO "setup request %02x %02x value %04x index %04x %04x\n",
+	 *	ctrl->bRequestType, ctrl->bRequest, le16_to_cpu(ctrl->wValue),
+	 *	le16_to_cpu(ctrl->wIndex), le16_to_cpu(ctrl->wLength));
+	 */
+
+	if ((ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS) {
+		INFO(f->config->cdev, "invalid request type\n");
+		return -EINVAL;
+	}
+
+	/* Stall too big requests. */
+	if (le16_to_cpu(ctrl->wLength) > UVC_MAX_REQUEST_SIZE)
+		return -EINVAL;
+
+	memset(&v4l2_event, 0, sizeof(v4l2_event));
+	v4l2_event.type = UVC_EVENT_SETUP;
+	memcpy(&uvc_event->req, ctrl, sizeof(uvc_event->req));
+	v4l2_event_queue(uvc->vdev, &v4l2_event);
+
+	return 0;
+}
+
+static int
+uvc_function_get_alt(struct usb_function *f, unsigned interface)
+{
+	struct uvc_device *uvc = to_uvc(f);
+
+	INFO(f->config->cdev, "uvc_function_get_alt(%u)\n", interface);
+
+	if (interface == uvc->control_intf)
+		return 0;
+	else if (interface != uvc->streaming_intf)
+		return -EINVAL;
+	else
+		return uvc->state == UVC_STATE_STREAMING ? 1 : 0;
+}
+
+static int
+uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned alt)
+{
+	struct uvc_device *uvc = to_uvc(f);
+	struct v4l2_event v4l2_event;
+	struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
+
+	INFO(f->config->cdev, "uvc_function_set_alt(%u, %u)\n", interface, alt);
+
+	if (interface == uvc->control_intf) {
+		if (alt)
+			return -EINVAL;
+
+		if (uvc->state == UVC_STATE_DISCONNECTED) {
+			memset(&v4l2_event, 0, sizeof(v4l2_event));
+			v4l2_event.type = UVC_EVENT_CONNECT;
+			uvc_event->speed = f->config->cdev->gadget->speed;
+			v4l2_event_queue(uvc->vdev, &v4l2_event);
+
+			uvc->state = UVC_STATE_CONNECTED;
+		}
+
+		return 0;
+	}
+
+	if (interface != uvc->streaming_intf)
+		return -EINVAL;
+
+	/* TODO
+	if (usb_endpoint_xfer_bulk(&uvc->desc.vs_ep))
+		return alt ? -EINVAL : 0;
+	*/
+
+	switch (alt) {
+	case 0:
+		if (uvc->state != UVC_STATE_STREAMING)
+			return 0;
+
+		if (uvc->video.ep)
+			usb_ep_disable(uvc->video.ep);
+
+		memset(&v4l2_event, 0, sizeof(v4l2_event));
+		v4l2_event.type = UVC_EVENT_STREAMOFF;
+		v4l2_event_queue(uvc->vdev, &v4l2_event);
+
+		uvc->state = UVC_STATE_CONNECTED;
+		break;
+
+	case 1:
+		if (uvc->state != UVC_STATE_CONNECTED)
+			return 0;
+
+		if (uvc->video.ep)
+			usb_ep_enable(uvc->video.ep, &uvc_streaming_ep);
+
+		memset(&v4l2_event, 0, sizeof(v4l2_event));
+		v4l2_event.type = UVC_EVENT_STREAMON;
+		v4l2_event_queue(uvc->vdev, &v4l2_event);
+
+		uvc->state = UVC_STATE_STREAMING;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void
+uvc_function_disable(struct usb_function *f)
+{
+	struct uvc_device *uvc = to_uvc(f);
+	struct v4l2_event v4l2_event;
+
+	INFO(f->config->cdev, "uvc_function_disable\n");
+
+	memset(&v4l2_event, 0, sizeof(v4l2_event));
+	v4l2_event.type = UVC_EVENT_DISCONNECT;
+	v4l2_event_queue(uvc->vdev, &v4l2_event);
+
+	uvc->state = UVC_STATE_DISCONNECTED;
+}
+
+/* --------------------------------------------------------------------------
+ * Connection / disconnection
+ */
+
+void
+uvc_function_connect(struct uvc_device *uvc)
+{
+	struct usb_composite_dev *cdev = uvc->func.config->cdev;
+	int ret;
+
+	if ((ret = usb_function_activate(&uvc->func)) < 0)
+		INFO(cdev, "UVC connect failed with %d\n", ret);
+}
+
+void
+uvc_function_disconnect(struct uvc_device *uvc)
+{
+	struct usb_composite_dev *cdev = uvc->func.config->cdev;
+	int ret;
+
+	if ((ret = usb_function_deactivate(&uvc->func)) < 0)
+		INFO(cdev, "UVC disconnect failed with %d\n", ret);
+}
+
+/* --------------------------------------------------------------------------
+ * USB probe and disconnect
+ */
+
+static int
+uvc_register_video(struct uvc_device *uvc)
+{
+	struct usb_composite_dev *cdev = uvc->func.config->cdev;
+	struct video_device *video;
+
+	/* TODO reference counting. */
+	video = video_device_alloc();
+	if (video == NULL)
+		return -ENOMEM;
+
+	video->parent = &cdev->gadget->dev;
+	video->minor = -1;
+	video->fops = &uvc_v4l2_fops;
+	video->release = video_device_release;
+	strncpy(video->name, cdev->gadget->name, sizeof(video->name));
+
+	uvc->vdev = video;
+	video_set_drvdata(video, uvc);
+
+	return video_register_device(video, VFL_TYPE_GRABBER, -1);
+}
+
+#define UVC_COPY_DESCRIPTOR(mem, dst, desc) \
+	do { \
+		memcpy(mem, desc, (desc)->bLength); \
+		*(dst)++ = mem; \
+		mem += (desc)->bLength; \
+	} while (0);
+
+#define UVC_COPY_DESCRIPTORS(mem, dst, src) \
+	do { \
+		const struct usb_descriptor_header * const *__src; \
+		for (__src = src; *__src; ++__src) { \
+			memcpy(mem, *__src, (*__src)->bLength); \
+			*dst++ = mem; \
+			mem += (*__src)->bLength; \
+		} \
+	} while (0)
+
+static struct usb_descriptor_header ** __init
+uvc_copy_descriptors(struct uvc_device *uvc, enum usb_device_speed speed)
+{
+	struct uvc_input_header_descriptor *uvc_streaming_header;
+	struct uvc_header_descriptor *uvc_control_header;
+	const struct uvc_descriptor_header * const *uvc_streaming_cls;
+	const struct usb_descriptor_header * const *uvc_streaming_std;
+	const struct usb_descriptor_header * const *src;
+	struct usb_descriptor_header **dst;
+	struct usb_descriptor_header **hdr;
+	unsigned int control_size;
+	unsigned int streaming_size;
+	unsigned int n_desc;
+	unsigned int bytes;
+	void *mem;
+
+	uvc_streaming_cls = (speed == USB_SPEED_FULL)
+			  ? uvc->desc.fs_streaming : uvc->desc.hs_streaming;
+	uvc_streaming_std = (speed == USB_SPEED_FULL)
+			  ? uvc_fs_streaming : uvc_hs_streaming;
+
+	/* Descriptors layout
+	 *
+	 * uvc_iad
+	 * uvc_control_intf
+	 * Class-specific UVC control descriptors
+	 * uvc_control_ep
+	 * uvc_control_cs_ep
+	 * uvc_streaming_intf_alt0
+	 * Class-specific UVC streaming descriptors
+	 * uvc_{fs|hs}_streaming
+	 */
+
+	/* Count descriptors and compute their size. */
+	control_size = 0;
+	streaming_size = 0;
+	bytes = uvc_iad.bLength + uvc_control_intf.bLength
+	      + uvc_control_ep.bLength + uvc_control_cs_ep.bLength
+	      + uvc_streaming_intf_alt0.bLength;
+	n_desc = 5;
+
+	for (src = (const struct usb_descriptor_header**)uvc->desc.control; *src; ++src) {
+		control_size += (*src)->bLength;
+		bytes += (*src)->bLength;
+		n_desc++;
+	}
+	for (src = (const struct usb_descriptor_header**)uvc_streaming_cls; *src; ++src) {
+		streaming_size += (*src)->bLength;
+		bytes += (*src)->bLength;
+		n_desc++;
+	}
+	for (src = uvc_streaming_std; *src; ++src) {
+		bytes += (*src)->bLength;
+		n_desc++;
+	}
+
+	mem = kmalloc((n_desc + 1) * sizeof(*src) + bytes, GFP_KERNEL);
+	if (mem == NULL)
+		return NULL;
+
+	hdr = mem;
+	dst = mem;
+	mem += (n_desc + 1) * sizeof(*src);
+
+	/* Copy the descriptors. */
+	UVC_COPY_DESCRIPTOR(mem, dst, &uvc_iad);
+	UVC_COPY_DESCRIPTOR(mem, dst, &uvc_control_intf);
+
+	uvc_control_header = mem;
+	UVC_COPY_DESCRIPTORS(mem, dst,
+		(const struct usb_descriptor_header**)uvc->desc.control);
+	uvc_control_header->wTotalLength = cpu_to_le16(control_size);
+	uvc_control_header->bInCollection = 1;
+	uvc_control_header->baInterfaceNr[0] = uvc->streaming_intf;
+
+	UVC_COPY_DESCRIPTOR(mem, dst, &uvc_control_ep);
+	UVC_COPY_DESCRIPTOR(mem, dst, &uvc_control_cs_ep);
+	UVC_COPY_DESCRIPTOR(mem, dst, &uvc_streaming_intf_alt0);
+
+	uvc_streaming_header = mem;
+	UVC_COPY_DESCRIPTORS(mem, dst,
+		(const struct usb_descriptor_header**)uvc_streaming_cls);
+	uvc_streaming_header->wTotalLength = cpu_to_le16(streaming_size);
+	uvc_streaming_header->bEndpointAddress = uvc_streaming_ep.bEndpointAddress;
+
+	UVC_COPY_DESCRIPTORS(mem, dst, uvc_streaming_std);
+
+	*dst = NULL;
+	return hdr;
+}
+
+static void
+uvc_function_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct uvc_device *uvc = to_uvc(f);
+
+	INFO(cdev, "uvc_function_unbind\n");
+
+	if (uvc->vdev) {
+		if (uvc->vdev->minor == -1)
+			video_device_release(uvc->vdev);
+		else
+			video_unregister_device(uvc->vdev);
+		uvc->vdev = NULL;
+	}
+
+	if (uvc->control_ep)
+		uvc->control_ep->driver_data = NULL;
+	if (uvc->video.ep)
+		uvc->video.ep->driver_data = NULL;
+
+	if (uvc->control_req) {
+		usb_ep_free_request(cdev->gadget->ep0, uvc->control_req);
+		kfree(uvc->control_buf);
+	}
+
+	kfree(f->descriptors);
+	kfree(f->hs_descriptors);
+
+	kfree(uvc);
+}
+
+static int __init
+uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct uvc_device *uvc = to_uvc(f);
+	struct usb_ep *ep;
+	int ret = -EINVAL;
+
+	INFO(cdev, "uvc_function_bind\n");
+
+	/* Allocate endpoints. */
+	ep = usb_ep_autoconfig(cdev->gadget, &uvc_control_ep);
+	if (!ep) {
+		INFO(cdev, "Unable to allocate control EP\n");
+		goto error;
+	}
+	uvc->control_ep = ep;
+	ep->driver_data = uvc;
+
+	ep = usb_ep_autoconfig(cdev->gadget, &uvc_streaming_ep);
+	if (!ep) {
+		INFO(cdev, "Unable to allocate streaming EP\n");
+		goto error;
+	}
+	uvc->video.ep = ep;
+	ep->driver_data = uvc;
+
+	/* Allocate interface IDs. */
+	if ((ret = usb_interface_id(c, f)) < 0)
+		goto error;
+	uvc_iad.bFirstInterface = ret;
+	uvc_control_intf.bInterfaceNumber = ret;
+	uvc->control_intf = ret;
+
+	if ((ret = usb_interface_id(c, f)) < 0)
+		goto error;
+	uvc_streaming_intf_alt0.bInterfaceNumber = ret;
+	uvc_streaming_intf_alt1.bInterfaceNumber = ret;
+	uvc->streaming_intf = ret;
+
+	/* Copy descriptors. */
+	f->descriptors = uvc_copy_descriptors(uvc, USB_SPEED_FULL);
+	f->hs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_HIGH);
+
+	/* Preallocate control endpoint request. */
+	uvc->control_req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
+	uvc->control_buf = kmalloc(UVC_MAX_REQUEST_SIZE, GFP_KERNEL);
+	if (uvc->control_req == NULL || uvc->control_buf == NULL) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	uvc->control_req->buf = uvc->control_buf;
+	uvc->control_req->complete = uvc_function_ep0_complete;
+	uvc->control_req->context = uvc;
+
+	/* Avoid letting this gadget enumerate until the userspace server is
+	 * active.
+	 */
+	if ((ret = usb_function_deactivate(f)) < 0)
+		goto error;
+
+	/* Initialise video. */
+	ret = uvc_video_init(&uvc->video);
+	if (ret < 0)
+		goto error;
+
+	/* Register a V4L2 device. */
+	ret = uvc_register_video(uvc);
+	if (ret < 0) {
+		printk(KERN_INFO "Unable to register video device\n");
+		goto error;
+	}
+
+	return 0;
+
+error:
+	uvc_function_unbind(c, f);
+	return ret;
+}
+
+/* --------------------------------------------------------------------------
+ * USB gadget function
+ */
+
+/**
+ * uvc_bind_config - add a UVC function to a configuration
+ * @c: the configuration to support the UVC instance
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ *
+ * Caller must have called @uvc_setup(). Caller is also responsible for
+ * calling @uvc_cleanup() before module unload.
+ */
+int __init
+uvc_bind_config(struct usb_configuration *c,
+		const struct uvc_descriptor_header * const *control,
+		const struct uvc_descriptor_header * const *fs_streaming,
+		const struct uvc_descriptor_header * const *hs_streaming)
+{
+	struct uvc_device *uvc;
+	int ret = 0;
+
+	/* TODO Check if the USB device controller supports the required
+	 * features.
+	 */
+	if (!gadget_is_dualspeed(c->cdev->gadget))
+		return -EINVAL;
+
+	uvc = kzalloc(sizeof(*uvc), GFP_KERNEL);
+	if (uvc == NULL)
+		return -ENOMEM;
+
+	uvc->state = UVC_STATE_DISCONNECTED;
+
+	/* Validate the descriptors. */
+	if (control == NULL || control[0] == NULL ||
+	    control[0]->bDescriptorSubType != UVC_DT_HEADER)
+		goto error;
+
+	if (fs_streaming == NULL || fs_streaming[0] == NULL ||
+	    fs_streaming[0]->bDescriptorSubType != UVC_DT_INPUT_HEADER)
+		goto error;
+
+	if (hs_streaming == NULL || hs_streaming[0] == NULL ||
+	    hs_streaming[0]->bDescriptorSubType != UVC_DT_INPUT_HEADER)
+		goto error;
+
+	uvc->desc.control = control;
+	uvc->desc.fs_streaming = fs_streaming;
+	uvc->desc.hs_streaming = hs_streaming;
+
+	/* Allocate string descriptor numbers. */
+	if ((ret = usb_string_id(c->cdev)) < 0)
+		goto error;
+	uvc_en_us_strings[UVC_STRING_ASSOCIATION_IDX].id = ret;
+	uvc_iad.iFunction = ret;
+
+	if ((ret = usb_string_id(c->cdev)) < 0)
+		goto error;
+	uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id = ret;
+	uvc_control_intf.iInterface = ret;
+
+	if ((ret = usb_string_id(c->cdev)) < 0)
+		goto error;
+	uvc_en_us_strings[UVC_STRING_STREAMING_IDX].id = ret;
+	uvc_streaming_intf_alt0.iInterface = ret;
+	uvc_streaming_intf_alt1.iInterface = ret;
+
+	/* Register the function. */
+	uvc->func.name = "uvc";
+	uvc->func.strings = uvc_function_strings;
+	uvc->func.bind = uvc_function_bind;
+	uvc->func.unbind = uvc_function_unbind;
+	uvc->func.get_alt = uvc_function_get_alt;
+	uvc->func.set_alt = uvc_function_set_alt;
+	uvc->func.disable = uvc_function_disable;
+	uvc->func.setup = uvc_function_setup;
+
+	ret = usb_add_function(c, &uvc->func);
+	if (ret)
+		kfree(uvc);
+
+	return 0;
+
+error:
+	kfree(uvc);
+	return ret;
+}
+
+module_param_named(trace, uvc_trace_param, uint, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(trace, "Trace level bitmask");
+