usb: gadget: Gadget directory cleanup - group usb functions

The drivers/usb/gadget directory contains many files.
Files which are related can be distributed into separate directories.
This patch moves the USB functions implementations into a separate directory.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 1029 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_rndis.c b/drivers/usb/gadget/function/f_rndis.c
new file mode 100644
index 000000000000..eed3ad878047
--- /dev/null
+++ b/drivers/usb/gadget/function/f_rndis.c
@@ -0,0 +1,1029 @@
+/*
+ * f_rndis.c -- RNDIS link function driver
+ *
+ * Copyright (C) 2003-2005,2008 David Brownell
+ * Copyright (C) 2003-2004 Robert Schwebel, Benedikt Spranger
+ * Copyright (C) 2008 Nokia Corporation
+ * Copyright (C) 2009 Samsung Electronics
+ *                    Author: Michal Nazarewicz (mina86@mina86.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.
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/etherdevice.h>
+
+#include <linux/atomic.h>
+
+#include "u_ether.h"
+#include "u_ether_configfs.h"
+#include "u_rndis.h"
+#include "rndis.h"
+#include "configfs.h"
+
+/*
+ * This function is an RNDIS Ethernet port -- a Microsoft protocol that's
+ * been promoted instead of the standard CDC Ethernet.  The published RNDIS
+ * spec is ambiguous, incomplete, and needlessly complex.  Variants such as
+ * ActiveSync have even worse status in terms of specification.
+ *
+ * In short:  it's a protocol controlled by (and for) Microsoft, not for an
+ * Open ecosystem or markets.  Linux supports it *only* because Microsoft
+ * doesn't support the CDC Ethernet standard.
+ *
+ * The RNDIS data transfer model is complex, with multiple Ethernet packets
+ * per USB message, and out of band data.  The control model is built around
+ * what's essentially an "RNDIS RPC" protocol.  It's all wrapped in a CDC ACM
+ * (modem, not Ethernet) veneer, with those ACM descriptors being entirely
+ * useless (they're ignored).  RNDIS expects to be the only function in its
+ * configuration, so it's no real help if you need composite devices; and
+ * it expects to be the first configuration too.
+ *
+ * There is a single technical advantage of RNDIS over CDC Ethernet, if you
+ * discount the fluff that its RPC can be made to deliver: it doesn't need
+ * a NOP altsetting for the data interface.  That lets it work on some of the
+ * "so smart it's stupid" hardware which takes over configuration changes
+ * from the software, and adds restrictions like "no altsettings".
+ *
+ * Unfortunately MSFT's RNDIS drivers are buggy.  They hang or oops, and
+ * have all sorts of contrary-to-specification oddities that can prevent
+ * them from working sanely.  Since bugfixes (or accurate specs, letting
+ * Linux work around those bugs) are unlikely to ever come from MSFT, you
+ * may want to avoid using RNDIS on purely operational grounds.
+ *
+ * Omissions from the RNDIS 1.0 specification include:
+ *
+ *   - Power management ... references data that's scattered around lots
+ *     of other documentation, which is incorrect/incomplete there too.
+ *
+ *   - There are various undocumented protocol requirements, like the need
+ *     to send garbage in some control-OUT messages.
+ *
+ *   - MS-Windows drivers sometimes emit undocumented requests.
+ */
+
+struct f_rndis {
+	struct gether			port;
+	u8				ctrl_id, data_id;
+	u8				ethaddr[ETH_ALEN];
+	u32				vendorID;
+	const char			*manufacturer;
+	int				config;
+
+	struct usb_ep			*notify;
+	struct usb_request		*notify_req;
+	atomic_t			notify_count;
+};
+
+static inline struct f_rndis *func_to_rndis(struct usb_function *f)
+{
+	return container_of(f, struct f_rndis, port.func);
+}
+
+/* peak (theoretical) bulk transfer rate in bits-per-second */
+static unsigned int bitrate(struct usb_gadget *g)
+{
+	if (gadget_is_superspeed(g) && g->speed == USB_SPEED_SUPER)
+		return 13 * 1024 * 8 * 1000 * 8;
+	else if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
+		return 13 * 512 * 8 * 1000 * 8;
+	else
+		return 19 * 64 * 1 * 1000 * 8;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ */
+
+#define RNDIS_STATUS_INTERVAL_MS	32
+#define STATUS_BYTECOUNT		8	/* 8 bytes data */
+
+
+/* interface descriptor: */
+
+static struct usb_interface_descriptor rndis_control_intf = {
+	.bLength =		sizeof rndis_control_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	/* .bInterfaceNumber = DYNAMIC */
+	/* status endpoint is optional; this could be patched later */
+	.bNumEndpoints =	1,
+	.bInterfaceClass =	USB_CLASS_COMM,
+	.bInterfaceSubClass =   USB_CDC_SUBCLASS_ACM,
+	.bInterfaceProtocol =   USB_CDC_ACM_PROTO_VENDOR,
+	/* .iInterface = DYNAMIC */
+};
+
+static struct usb_cdc_header_desc header_desc = {
+	.bLength =		sizeof header_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
+
+	.bcdCDC =		cpu_to_le16(0x0110),
+};
+
+static struct usb_cdc_call_mgmt_descriptor call_mgmt_descriptor = {
+	.bLength =		sizeof call_mgmt_descriptor,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_CALL_MANAGEMENT_TYPE,
+
+	.bmCapabilities =	0x00,
+	.bDataInterface =	0x01,
+};
+
+static struct usb_cdc_acm_descriptor rndis_acm_descriptor = {
+	.bLength =		sizeof rndis_acm_descriptor,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_ACM_TYPE,
+
+	.bmCapabilities =	0x00,
+};
+
+static struct usb_cdc_union_desc rndis_union_desc = {
+	.bLength =		sizeof(rndis_union_desc),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
+	/* .bMasterInterface0 =	DYNAMIC */
+	/* .bSlaveInterface0 =	DYNAMIC */
+};
+
+/* the data interface has two bulk endpoints */
+
+static struct usb_interface_descriptor rndis_data_intf = {
+	.bLength =		sizeof rndis_data_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	/* .bInterfaceNumber = DYNAMIC */
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_CDC_DATA,
+	.bInterfaceSubClass =	0,
+	.bInterfaceProtocol =	0,
+	/* .iInterface = DYNAMIC */
+};
+
+
+static struct usb_interface_assoc_descriptor
+rndis_iad_descriptor = {
+	.bLength =		sizeof rndis_iad_descriptor,
+	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,
+
+	.bFirstInterface =	0, /* XXX, hardcoded */
+	.bInterfaceCount = 	2,	// control + data
+	.bFunctionClass =	USB_CLASS_COMM,
+	.bFunctionSubClass =	USB_CDC_SUBCLASS_ETHERNET,
+	.bFunctionProtocol =	USB_CDC_PROTO_NONE,
+	/* .iFunction = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor fs_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(STATUS_BYTECOUNT),
+	.bInterval =		RNDIS_STATUS_INTERVAL_MS,
+};
+
+static struct usb_endpoint_descriptor fs_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *eth_fs_function[] = {
+	(struct usb_descriptor_header *) &rndis_iad_descriptor,
+
+	/* control interface matches ACM, not Ethernet */
+	(struct usb_descriptor_header *) &rndis_control_intf,
+	(struct usb_descriptor_header *) &header_desc,
+	(struct usb_descriptor_header *) &call_mgmt_descriptor,
+	(struct usb_descriptor_header *) &rndis_acm_descriptor,
+	(struct usb_descriptor_header *) &rndis_union_desc,
+	(struct usb_descriptor_header *) &fs_notify_desc,
+
+	/* data interface has no altsetting */
+	(struct usb_descriptor_header *) &rndis_data_intf,
+	(struct usb_descriptor_header *) &fs_in_desc,
+	(struct usb_descriptor_header *) &fs_out_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(STATUS_BYTECOUNT),
+	.bInterval =		USB_MS_TO_HS_INTERVAL(RNDIS_STATUS_INTERVAL_MS)
+};
+
+static struct usb_endpoint_descriptor hs_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *eth_hs_function[] = {
+	(struct usb_descriptor_header *) &rndis_iad_descriptor,
+
+	/* control interface matches ACM, not Ethernet */
+	(struct usb_descriptor_header *) &rndis_control_intf,
+	(struct usb_descriptor_header *) &header_desc,
+	(struct usb_descriptor_header *) &call_mgmt_descriptor,
+	(struct usb_descriptor_header *) &rndis_acm_descriptor,
+	(struct usb_descriptor_header *) &rndis_union_desc,
+	(struct usb_descriptor_header *) &hs_notify_desc,
+
+	/* data interface has no altsetting */
+	(struct usb_descriptor_header *) &rndis_data_intf,
+	(struct usb_descriptor_header *) &hs_in_desc,
+	(struct usb_descriptor_header *) &hs_out_desc,
+	NULL,
+};
+
+/* super speed support: */
+
+static struct usb_endpoint_descriptor ss_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(STATUS_BYTECOUNT),
+	.bInterval =		USB_MS_TO_HS_INTERVAL(RNDIS_STATUS_INTERVAL_MS)
+};
+
+static struct usb_ss_ep_comp_descriptor ss_intr_comp_desc = {
+	.bLength =		sizeof ss_intr_comp_desc,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+
+	/* the following 3 values can be tweaked if necessary */
+	/* .bMaxBurst =		0, */
+	/* .bmAttributes =	0, */
+	.wBytesPerInterval =	cpu_to_le16(STATUS_BYTECOUNT),
+};
+
+static struct usb_endpoint_descriptor ss_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_endpoint_descriptor ss_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_bulk_comp_desc = {
+	.bLength =		sizeof ss_bulk_comp_desc,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+
+	/* the following 2 values can be tweaked if necessary */
+	/* .bMaxBurst =		0, */
+	/* .bmAttributes =	0, */
+};
+
+static struct usb_descriptor_header *eth_ss_function[] = {
+	(struct usb_descriptor_header *) &rndis_iad_descriptor,
+
+	/* control interface matches ACM, not Ethernet */
+	(struct usb_descriptor_header *) &rndis_control_intf,
+	(struct usb_descriptor_header *) &header_desc,
+	(struct usb_descriptor_header *) &call_mgmt_descriptor,
+	(struct usb_descriptor_header *) &rndis_acm_descriptor,
+	(struct usb_descriptor_header *) &rndis_union_desc,
+	(struct usb_descriptor_header *) &ss_notify_desc,
+	(struct usb_descriptor_header *) &ss_intr_comp_desc,
+
+	/* data interface has no altsetting */
+	(struct usb_descriptor_header *) &rndis_data_intf,
+	(struct usb_descriptor_header *) &ss_in_desc,
+	(struct usb_descriptor_header *) &ss_bulk_comp_desc,
+	(struct usb_descriptor_header *) &ss_out_desc,
+	(struct usb_descriptor_header *) &ss_bulk_comp_desc,
+	NULL,
+};
+
+/* string descriptors: */
+
+static struct usb_string rndis_string_defs[] = {
+	[0].s = "RNDIS Communications Control",
+	[1].s = "RNDIS Ethernet Data",
+	[2].s = "RNDIS",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings rndis_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		rndis_string_defs,
+};
+
+static struct usb_gadget_strings *rndis_strings[] = {
+	&rndis_string_table,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static struct sk_buff *rndis_add_header(struct gether *port,
+					struct sk_buff *skb)
+{
+	struct sk_buff *skb2;
+
+	skb2 = skb_realloc_headroom(skb, sizeof(struct rndis_packet_msg_type));
+	if (skb2)
+		rndis_add_hdr(skb2);
+
+	dev_kfree_skb(skb);
+	return skb2;
+}
+
+static void rndis_response_available(void *_rndis)
+{
+	struct f_rndis			*rndis = _rndis;
+	struct usb_request		*req = rndis->notify_req;
+	struct usb_composite_dev	*cdev = rndis->port.func.config->cdev;
+	__le32				*data = req->buf;
+	int				status;
+
+	if (atomic_inc_return(&rndis->notify_count) != 1)
+		return;
+
+	/* Send RNDIS RESPONSE_AVAILABLE notification; a
+	 * USB_CDC_NOTIFY_RESPONSE_AVAILABLE "should" work too
+	 *
+	 * This is the only notification defined by RNDIS.
+	 */
+	data[0] = cpu_to_le32(1);
+	data[1] = cpu_to_le32(0);
+
+	status = usb_ep_queue(rndis->notify, req, GFP_ATOMIC);
+	if (status) {
+		atomic_dec(&rndis->notify_count);
+		DBG(cdev, "notify/0 --> %d\n", status);
+	}
+}
+
+static void rndis_response_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_rndis			*rndis = req->context;
+	struct usb_composite_dev	*cdev = rndis->port.func.config->cdev;
+	int				status = req->status;
+
+	/* after TX:
+	 *  - USB_CDC_GET_ENCAPSULATED_RESPONSE (ep0/control)
+	 *  - RNDIS_RESPONSE_AVAILABLE (status/irq)
+	 */
+	switch (status) {
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		/* connection gone */
+		atomic_set(&rndis->notify_count, 0);
+		break;
+	default:
+		DBG(cdev, "RNDIS %s response error %d, %d/%d\n",
+			ep->name, status,
+			req->actual, req->length);
+		/* FALLTHROUGH */
+	case 0:
+		if (ep != rndis->notify)
+			break;
+
+		/* handle multiple pending RNDIS_RESPONSE_AVAILABLE
+		 * notifications by resending until we're done
+		 */
+		if (atomic_dec_and_test(&rndis->notify_count))
+			break;
+		status = usb_ep_queue(rndis->notify, req, GFP_ATOMIC);
+		if (status) {
+			atomic_dec(&rndis->notify_count);
+			DBG(cdev, "notify/1 --> %d\n", status);
+		}
+		break;
+	}
+}
+
+static void rndis_command_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_rndis			*rndis = req->context;
+	int				status;
+
+	/* received RNDIS command from USB_CDC_SEND_ENCAPSULATED_COMMAND */
+//	spin_lock(&dev->lock);
+	status = rndis_msg_parser(rndis->config, (u8 *) req->buf);
+	if (status < 0)
+		pr_err("RNDIS command error %d, %d/%d\n",
+			status, req->actual, req->length);
+//	spin_unlock(&dev->lock);
+}
+
+static int
+rndis_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct f_rndis		*rndis = func_to_rndis(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct usb_request	*req = cdev->req;
+	int			value = -EOPNOTSUPP;
+	u16			w_index = le16_to_cpu(ctrl->wIndex);
+	u16			w_value = le16_to_cpu(ctrl->wValue);
+	u16			w_length = le16_to_cpu(ctrl->wLength);
+
+	/* composite driver infrastructure handles everything except
+	 * CDC class messages; interface activation uses set_alt().
+	 */
+	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
+
+	/* RNDIS uses the CDC command encapsulation mechanism to implement
+	 * an RPC scheme, with much getting/setting of attributes by OID.
+	 */
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_SEND_ENCAPSULATED_COMMAND:
+		if (w_value || w_index != rndis->ctrl_id)
+			goto invalid;
+		/* read the request; process it later */
+		value = w_length;
+		req->complete = rndis_command_complete;
+		req->context = rndis;
+		/* later, rndis_response_available() sends a notification */
+		break;
+
+	case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_GET_ENCAPSULATED_RESPONSE:
+		if (w_value || w_index != rndis->ctrl_id)
+			goto invalid;
+		else {
+			u8 *buf;
+			u32 n;
+
+			/* return the result */
+			buf = rndis_get_next_response(rndis->config, &n);
+			if (buf) {
+				memcpy(req->buf, buf, n);
+				req->complete = rndis_response_complete;
+				req->context = rndis;
+				rndis_free_response(rndis->config, buf);
+				value = n;
+			}
+			/* else stalls ... spec says to avoid that */
+		}
+		break;
+
+	default:
+invalid:
+		VDBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+	}
+
+	/* respond with data transfer or status phase? */
+	if (value >= 0) {
+		DBG(cdev, "rndis req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+		req->zero = (value < w_length);
+		req->length = value;
+		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0)
+			ERROR(cdev, "rndis response on err %d\n", value);
+	}
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+
+static int rndis_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_rndis		*rndis = func_to_rndis(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	/* we know alt == 0 */
+
+	if (intf == rndis->ctrl_id) {
+		if (rndis->notify->driver_data) {
+			VDBG(cdev, "reset rndis control %d\n", intf);
+			usb_ep_disable(rndis->notify);
+		}
+		if (!rndis->notify->desc) {
+			VDBG(cdev, "init rndis ctrl %d\n", intf);
+			if (config_ep_by_speed(cdev->gadget, f, rndis->notify))
+				goto fail;
+		}
+		usb_ep_enable(rndis->notify);
+		rndis->notify->driver_data = rndis;
+
+	} else if (intf == rndis->data_id) {
+		struct net_device	*net;
+
+		if (rndis->port.in_ep->driver_data) {
+			DBG(cdev, "reset rndis\n");
+			gether_disconnect(&rndis->port);
+		}
+
+		if (!rndis->port.in_ep->desc || !rndis->port.out_ep->desc) {
+			DBG(cdev, "init rndis\n");
+			if (config_ep_by_speed(cdev->gadget, f,
+					       rndis->port.in_ep) ||
+			    config_ep_by_speed(cdev->gadget, f,
+					       rndis->port.out_ep)) {
+				rndis->port.in_ep->desc = NULL;
+				rndis->port.out_ep->desc = NULL;
+				goto fail;
+			}
+		}
+
+		/* Avoid ZLPs; they can be troublesome. */
+		rndis->port.is_zlp_ok = false;
+
+		/* RNDIS should be in the "RNDIS uninitialized" state,
+		 * either never activated or after rndis_uninit().
+		 *
+		 * We don't want data to flow here until a nonzero packet
+		 * filter is set, at which point it enters "RNDIS data
+		 * initialized" state ... but we do want the endpoints
+		 * to be activated.  It's a strange little state.
+		 *
+		 * REVISIT the RNDIS gadget code has done this wrong for a
+		 * very long time.  We need another call to the link layer
+		 * code -- gether_updown(...bool) maybe -- to do it right.
+		 */
+		rndis->port.cdc_filter = 0;
+
+		DBG(cdev, "RNDIS RX/TX early activation ... \n");
+		net = gether_connect(&rndis->port);
+		if (IS_ERR(net))
+			return PTR_ERR(net);
+
+		rndis_set_param_dev(rndis->config, net,
+				&rndis->port.cdc_filter);
+	} else
+		goto fail;
+
+	return 0;
+fail:
+	return -EINVAL;
+}
+
+static void rndis_disable(struct usb_function *f)
+{
+	struct f_rndis		*rndis = func_to_rndis(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	if (!rndis->notify->driver_data)
+		return;
+
+	DBG(cdev, "rndis deactivated\n");
+
+	rndis_uninit(rndis->config);
+	gether_disconnect(&rndis->port);
+
+	usb_ep_disable(rndis->notify);
+	rndis->notify->driver_data = NULL;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * This isn't quite the same mechanism as CDC Ethernet, since the
+ * notification scheme passes less data, but the same set of link
+ * states must be tested.  A key difference is that altsettings are
+ * not used to tell whether the link should send packets or not.
+ */
+
+static void rndis_open(struct gether *geth)
+{
+	struct f_rndis		*rndis = func_to_rndis(&geth->func);
+	struct usb_composite_dev *cdev = geth->func.config->cdev;
+
+	DBG(cdev, "%s\n", __func__);
+
+	rndis_set_param_medium(rndis->config, RNDIS_MEDIUM_802_3,
+				bitrate(cdev->gadget) / 100);
+	rndis_signal_connect(rndis->config);
+}
+
+static void rndis_close(struct gether *geth)
+{
+	struct f_rndis		*rndis = func_to_rndis(&geth->func);
+
+	DBG(geth->func.config->cdev, "%s\n", __func__);
+
+	rndis_set_param_medium(rndis->config, RNDIS_MEDIUM_802_3, 0);
+	rndis_signal_disconnect(rndis->config);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Some controllers can't support RNDIS ... */
+static inline bool can_support_rndis(struct usb_configuration *c)
+{
+	/* everything else is *presumably* fine */
+	return true;
+}
+
+/* ethernet function driver setup/binding */
+
+static int
+rndis_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_rndis		*rndis = func_to_rndis(f);
+	struct usb_string	*us;
+	int			status;
+	struct usb_ep		*ep;
+
+	struct f_rndis_opts *rndis_opts;
+
+	if (!can_support_rndis(c))
+		return -EINVAL;
+
+	rndis_opts = container_of(f->fi, struct f_rndis_opts, func_inst);
+
+	if (cdev->use_os_string) {
+		f->os_desc_table = kzalloc(sizeof(*f->os_desc_table),
+					   GFP_KERNEL);
+		if (!f->os_desc_table)
+			return PTR_ERR(f->os_desc_table);
+		f->os_desc_n = 1;
+		f->os_desc_table[0].os_desc = &rndis_opts->rndis_os_desc;
+	}
+
+	/*
+	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
+	 * configurations are bound in sequence with list_for_each_entry,
+	 * in each configuration its functions are bound in sequence
+	 * with list_for_each_entry, so we assume no race condition
+	 * with regard to rndis_opts->bound access
+	 */
+	if (!rndis_opts->bound) {
+		gether_set_gadget(rndis_opts->net, cdev->gadget);
+		status = gether_register_netdev(rndis_opts->net);
+		if (status)
+			goto fail;
+		rndis_opts->bound = true;
+	}
+
+	us = usb_gstrings_attach(cdev, rndis_strings,
+				 ARRAY_SIZE(rndis_string_defs));
+	if (IS_ERR(us)) {
+		status = PTR_ERR(us);
+		goto fail;
+	}
+	rndis_control_intf.iInterface = us[0].id;
+	rndis_data_intf.iInterface = us[1].id;
+	rndis_iad_descriptor.iFunction = us[2].id;
+
+	/* allocate instance-specific interface IDs */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	rndis->ctrl_id = status;
+	rndis_iad_descriptor.bFirstInterface = status;
+
+	rndis_control_intf.bInterfaceNumber = status;
+	rndis_union_desc.bMasterInterface0 = status;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	rndis->data_id = status;
+
+	rndis_data_intf.bInterfaceNumber = status;
+	rndis_union_desc.bSlaveInterface0 = status;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_in_desc);
+	if (!ep)
+		goto fail;
+	rndis->port.in_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_out_desc);
+	if (!ep)
+		goto fail;
+	rndis->port.out_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	/* NOTE:  a status/notification endpoint is, strictly speaking,
+	 * optional.  We don't treat it that way though!  It's simpler,
+	 * and some newer profiles don't treat it as optional.
+	 */
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_notify_desc);
+	if (!ep)
+		goto fail;
+	rndis->notify = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	status = -ENOMEM;
+
+	/* allocate notification request and buffer */
+	rndis->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
+	if (!rndis->notify_req)
+		goto fail;
+	rndis->notify_req->buf = kmalloc(STATUS_BYTECOUNT, GFP_KERNEL);
+	if (!rndis->notify_req->buf)
+		goto fail;
+	rndis->notify_req->length = STATUS_BYTECOUNT;
+	rndis->notify_req->context = rndis;
+	rndis->notify_req->complete = rndis_response_complete;
+
+	/* support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	hs_in_desc.bEndpointAddress = fs_in_desc.bEndpointAddress;
+	hs_out_desc.bEndpointAddress = fs_out_desc.bEndpointAddress;
+	hs_notify_desc.bEndpointAddress = fs_notify_desc.bEndpointAddress;
+
+	ss_in_desc.bEndpointAddress = fs_in_desc.bEndpointAddress;
+	ss_out_desc.bEndpointAddress = fs_out_desc.bEndpointAddress;
+	ss_notify_desc.bEndpointAddress = fs_notify_desc.bEndpointAddress;
+
+	status = usb_assign_descriptors(f, eth_fs_function, eth_hs_function,
+			eth_ss_function);
+	if (status)
+		goto fail;
+
+	rndis->port.open = rndis_open;
+	rndis->port.close = rndis_close;
+
+	rndis_set_param_medium(rndis->config, RNDIS_MEDIUM_802_3, 0);
+	rndis_set_host_mac(rndis->config, rndis->ethaddr);
+
+	if (rndis->manufacturer && rndis->vendorID &&
+			rndis_set_param_vendor(rndis->config, rndis->vendorID,
+					       rndis->manufacturer))
+		goto fail;
+
+	/* NOTE:  all that is done without knowing or caring about
+	 * the network link ... which is unavailable to this code
+	 * until we're activated via set_alt().
+	 */
+
+	DBG(cdev, "RNDIS: %s speed IN/%s OUT/%s NOTIFY/%s\n",
+			gadget_is_superspeed(c->cdev->gadget) ? "super" :
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			rndis->port.in_ep->name, rndis->port.out_ep->name,
+			rndis->notify->name);
+	return 0;
+
+fail:
+	kfree(f->os_desc_table);
+	f->os_desc_n = 0;
+	usb_free_all_descriptors(f);
+
+	if (rndis->notify_req) {
+		kfree(rndis->notify_req->buf);
+		usb_ep_free_request(rndis->notify, rndis->notify_req);
+	}
+
+	/* we might as well release our claims on endpoints */
+	if (rndis->notify)
+		rndis->notify->driver_data = NULL;
+	if (rndis->port.out_ep)
+		rndis->port.out_ep->driver_data = NULL;
+	if (rndis->port.in_ep)
+		rndis->port.in_ep->driver_data = NULL;
+
+	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
+
+	return status;
+}
+
+void rndis_borrow_net(struct usb_function_instance *f, struct net_device *net)
+{
+	struct f_rndis_opts *opts;
+
+	opts = container_of(f, struct f_rndis_opts, func_inst);
+	if (opts->bound)
+		gether_cleanup(netdev_priv(opts->net));
+	else
+		free_netdev(opts->net);
+	opts->borrowed_net = opts->bound = true;
+	opts->net = net;
+}
+EXPORT_SYMBOL_GPL(rndis_borrow_net);
+
+static inline struct f_rndis_opts *to_f_rndis_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_rndis_opts,
+			    func_inst.group);
+}
+
+/* f_rndis_item_ops */
+USB_ETHERNET_CONFIGFS_ITEM(rndis);
+
+/* f_rndis_opts_dev_addr */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(rndis);
+
+/* f_rndis_opts_host_addr */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(rndis);
+
+/* f_rndis_opts_qmult */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(rndis);
+
+/* f_rndis_opts_ifname */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(rndis);
+
+static struct configfs_attribute *rndis_attrs[] = {
+	&f_rndis_opts_dev_addr.attr,
+	&f_rndis_opts_host_addr.attr,
+	&f_rndis_opts_qmult.attr,
+	&f_rndis_opts_ifname.attr,
+	NULL,
+};
+
+static struct config_item_type rndis_func_type = {
+	.ct_item_ops	= &rndis_item_ops,
+	.ct_attrs	= rndis_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static void rndis_free_inst(struct usb_function_instance *f)
+{
+	struct f_rndis_opts *opts;
+
+	opts = container_of(f, struct f_rndis_opts, func_inst);
+	if (!opts->borrowed_net) {
+		if (opts->bound)
+			gether_cleanup(netdev_priv(opts->net));
+		else
+			free_netdev(opts->net);
+	}
+
+	kfree(opts->rndis_os_desc.group.default_groups); /* single VLA chunk */
+	kfree(opts);
+}
+
+static struct usb_function_instance *rndis_alloc_inst(void)
+{
+	struct f_rndis_opts *opts;
+	struct usb_os_desc *descs[1];
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+	opts->rndis_os_desc.ext_compat_id = opts->rndis_ext_compat_id;
+
+	mutex_init(&opts->lock);
+	opts->func_inst.free_func_inst = rndis_free_inst;
+	opts->net = gether_setup_default();
+	if (IS_ERR(opts->net)) {
+		struct net_device *net = opts->net;
+		kfree(opts);
+		return ERR_CAST(net);
+	}
+	INIT_LIST_HEAD(&opts->rndis_os_desc.ext_prop);
+
+	descs[0] = &opts->rndis_os_desc;
+	usb_os_desc_prepare_interf_dir(&opts->func_inst.group, 1, descs,
+				       THIS_MODULE);
+	config_group_init_type_name(&opts->func_inst.group, "",
+				    &rndis_func_type);
+
+	return &opts->func_inst;
+}
+
+static void rndis_free(struct usb_function *f)
+{
+	struct f_rndis *rndis;
+	struct f_rndis_opts *opts;
+
+	rndis = func_to_rndis(f);
+	rndis_deregister(rndis->config);
+	opts = container_of(f->fi, struct f_rndis_opts, func_inst);
+	kfree(rndis);
+	mutex_lock(&opts->lock);
+	opts->refcnt--;
+	mutex_unlock(&opts->lock);
+}
+
+static void rndis_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_rndis		*rndis = func_to_rndis(f);
+
+	kfree(f->os_desc_table);
+	f->os_desc_n = 0;
+	usb_free_all_descriptors(f);
+
+	kfree(rndis->notify_req->buf);
+	usb_ep_free_request(rndis->notify, rndis->notify_req);
+}
+
+static struct usb_function *rndis_alloc(struct usb_function_instance *fi)
+{
+	struct f_rndis	*rndis;
+	struct f_rndis_opts *opts;
+	int status;
+
+	/* allocate and initialize one new instance */
+	rndis = kzalloc(sizeof(*rndis), GFP_KERNEL);
+	if (!rndis)
+		return ERR_PTR(-ENOMEM);
+
+	opts = container_of(fi, struct f_rndis_opts, func_inst);
+	mutex_lock(&opts->lock);
+	opts->refcnt++;
+
+	gether_get_host_addr_u8(opts->net, rndis->ethaddr);
+	rndis->vendorID = opts->vendor_id;
+	rndis->manufacturer = opts->manufacturer;
+
+	rndis->port.ioport = netdev_priv(opts->net);
+	mutex_unlock(&opts->lock);
+	/* RNDIS activates when the host changes this filter */
+	rndis->port.cdc_filter = 0;
+
+	/* RNDIS has special (and complex) framing */
+	rndis->port.header_len = sizeof(struct rndis_packet_msg_type);
+	rndis->port.wrap = rndis_add_header;
+	rndis->port.unwrap = rndis_rm_hdr;
+
+	rndis->port.func.name = "rndis";
+	/* descriptors are per-instance copies */
+	rndis->port.func.bind = rndis_bind;
+	rndis->port.func.unbind = rndis_unbind;
+	rndis->port.func.set_alt = rndis_set_alt;
+	rndis->port.func.setup = rndis_setup;
+	rndis->port.func.disable = rndis_disable;
+	rndis->port.func.free_func = rndis_free;
+
+	status = rndis_register(rndis_response_available, rndis);
+	if (status < 0) {
+		kfree(rndis);
+		return ERR_PTR(status);
+	}
+	rndis->config = status;
+
+	return &rndis->port.func;
+}
+
+DECLARE_USB_FUNCTION(rndis, rndis_alloc_inst, rndis_alloc);
+
+static int __init rndis_mod_init(void)
+{
+	int ret;
+
+	ret = rndis_init();
+	if (ret)
+		return ret;
+
+	return usb_function_register(&rndisusb_func);
+}
+module_init(rndis_mod_init);
+
+static void __exit rndis_mod_exit(void)
+{
+	usb_function_unregister(&rndisusb_func);
+	rndis_exit();
+}
+module_exit(rndis_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Brownell");