1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * f_eem.c -- USB CDC Ethernet (EEM) link function driver
4  *
5  * Copyright (C) 2003-2005,2008 David Brownell
6  * Copyright (C) 2008 Nokia Corporation
7  * Copyright (C) 2009 EF Johnson Technologies
8  */
9 
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/etherdevice.h>
14 #include <linux/crc32.h>
15 #include <linux/slab.h>
16 
17 #include "u_ether.h"
18 #include "u_ether_configfs.h"
19 #include "u_eem.h"
20 
21 #define EEM_HLEN 2
22 
23 /*
24  * This function is a "CDC Ethernet Emulation Model" (CDC EEM)
25  * Ethernet link.
26  */
27 
28 struct f_eem {
29 	struct gether			port;
30 	u8				ctrl_id;
31 };
32 
33 struct in_context {
34 	struct sk_buff	*skb;
35 	struct usb_ep	*ep;
36 };
37 
func_to_eem(struct usb_function * f)38 static inline struct f_eem *func_to_eem(struct usb_function *f)
39 {
40 	return container_of(f, struct f_eem, port.func);
41 }
42 
43 /*-------------------------------------------------------------------------*/
44 
45 /* interface descriptor: */
46 
47 static struct usb_interface_descriptor eem_intf = {
48 	.bLength =		sizeof eem_intf,
49 	.bDescriptorType =	USB_DT_INTERFACE,
50 
51 	/* .bInterfaceNumber = DYNAMIC */
52 	.bNumEndpoints =	2,
53 	.bInterfaceClass =	USB_CLASS_COMM,
54 	.bInterfaceSubClass =	USB_CDC_SUBCLASS_EEM,
55 	.bInterfaceProtocol =	USB_CDC_PROTO_EEM,
56 	/* .iInterface = DYNAMIC */
57 };
58 
59 /* full speed support: */
60 
61 static struct usb_endpoint_descriptor eem_fs_in_desc = {
62 	.bLength =		USB_DT_ENDPOINT_SIZE,
63 	.bDescriptorType =	USB_DT_ENDPOINT,
64 
65 	.bEndpointAddress =	USB_DIR_IN,
66 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
67 };
68 
69 static struct usb_endpoint_descriptor eem_fs_out_desc = {
70 	.bLength =		USB_DT_ENDPOINT_SIZE,
71 	.bDescriptorType =	USB_DT_ENDPOINT,
72 
73 	.bEndpointAddress =	USB_DIR_OUT,
74 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
75 };
76 
77 static struct usb_descriptor_header *eem_fs_function[] = {
78 	/* CDC EEM control descriptors */
79 	(struct usb_descriptor_header *) &eem_intf,
80 	(struct usb_descriptor_header *) &eem_fs_in_desc,
81 	(struct usb_descriptor_header *) &eem_fs_out_desc,
82 	NULL,
83 };
84 
85 /* high speed support: */
86 
87 static struct usb_endpoint_descriptor eem_hs_in_desc = {
88 	.bLength =		USB_DT_ENDPOINT_SIZE,
89 	.bDescriptorType =	USB_DT_ENDPOINT,
90 
91 	.bEndpointAddress =	USB_DIR_IN,
92 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
93 	.wMaxPacketSize =	cpu_to_le16(512),
94 };
95 
96 static struct usb_endpoint_descriptor eem_hs_out_desc = {
97 	.bLength =		USB_DT_ENDPOINT_SIZE,
98 	.bDescriptorType =	USB_DT_ENDPOINT,
99 
100 	.bEndpointAddress =	USB_DIR_OUT,
101 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
102 	.wMaxPacketSize =	cpu_to_le16(512),
103 };
104 
105 static struct usb_descriptor_header *eem_hs_function[] = {
106 	/* CDC EEM control descriptors */
107 	(struct usb_descriptor_header *) &eem_intf,
108 	(struct usb_descriptor_header *) &eem_hs_in_desc,
109 	(struct usb_descriptor_header *) &eem_hs_out_desc,
110 	NULL,
111 };
112 
113 /* super speed support: */
114 
115 static struct usb_endpoint_descriptor eem_ss_in_desc = {
116 	.bLength =		USB_DT_ENDPOINT_SIZE,
117 	.bDescriptorType =	USB_DT_ENDPOINT,
118 
119 	.bEndpointAddress =	USB_DIR_IN,
120 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
121 	.wMaxPacketSize =	cpu_to_le16(1024),
122 };
123 
124 static struct usb_endpoint_descriptor eem_ss_out_desc = {
125 	.bLength =		USB_DT_ENDPOINT_SIZE,
126 	.bDescriptorType =	USB_DT_ENDPOINT,
127 
128 	.bEndpointAddress =	USB_DIR_OUT,
129 	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
130 	.wMaxPacketSize =	cpu_to_le16(1024),
131 };
132 
133 static struct usb_ss_ep_comp_descriptor eem_ss_bulk_comp_desc = {
134 	.bLength =		sizeof eem_ss_bulk_comp_desc,
135 	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
136 
137 	/* the following 2 values can be tweaked if necessary */
138 	/* .bMaxBurst =		0, */
139 	/* .bmAttributes =	0, */
140 };
141 
142 static struct usb_descriptor_header *eem_ss_function[] = {
143 	/* CDC EEM control descriptors */
144 	(struct usb_descriptor_header *) &eem_intf,
145 	(struct usb_descriptor_header *) &eem_ss_in_desc,
146 	(struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
147 	(struct usb_descriptor_header *) &eem_ss_out_desc,
148 	(struct usb_descriptor_header *) &eem_ss_bulk_comp_desc,
149 	NULL,
150 };
151 
152 /* string descriptors: */
153 
154 static struct usb_string eem_string_defs[] = {
155 	[0].s = "CDC Ethernet Emulation Model (EEM)",
156 	{  } /* end of list */
157 };
158 
159 static struct usb_gadget_strings eem_string_table = {
160 	.language =		0x0409,	/* en-us */
161 	.strings =		eem_string_defs,
162 };
163 
164 static struct usb_gadget_strings *eem_strings[] = {
165 	&eem_string_table,
166 	NULL,
167 };
168 
169 /*-------------------------------------------------------------------------*/
170 
eem_setup(struct usb_function * f,const struct usb_ctrlrequest * ctrl)171 static int eem_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
172 {
173 	struct usb_composite_dev *cdev = f->config->cdev;
174 	u16			w_index = le16_to_cpu(ctrl->wIndex);
175 	u16			w_value = le16_to_cpu(ctrl->wValue);
176 	u16			w_length = le16_to_cpu(ctrl->wLength);
177 
178 	DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
179 		ctrl->bRequestType, ctrl->bRequest,
180 		w_value, w_index, w_length);
181 
182 	/* device either stalls (value < 0) or reports success */
183 	return -EOPNOTSUPP;
184 }
185 
186 
eem_set_alt(struct usb_function * f,unsigned intf,unsigned alt)187 static int eem_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
188 {
189 	struct f_eem		*eem = func_to_eem(f);
190 	struct usb_composite_dev *cdev = f->config->cdev;
191 	struct net_device	*net;
192 
193 	/* we know alt == 0, so this is an activation or a reset */
194 	if (alt != 0)
195 		goto fail;
196 
197 	if (intf == eem->ctrl_id) {
198 		DBG(cdev, "reset eem\n");
199 		gether_disconnect(&eem->port);
200 
201 		if (!eem->port.in_ep->desc || !eem->port.out_ep->desc) {
202 			DBG(cdev, "init eem\n");
203 			if (config_ep_by_speed(cdev->gadget, f,
204 					       eem->port.in_ep) ||
205 			    config_ep_by_speed(cdev->gadget, f,
206 					       eem->port.out_ep)) {
207 				eem->port.in_ep->desc = NULL;
208 				eem->port.out_ep->desc = NULL;
209 				goto fail;
210 			}
211 		}
212 
213 		/* zlps should not occur because zero-length EEM packets
214 		 * will be inserted in those cases where they would occur
215 		 */
216 		eem->port.is_zlp_ok = 1;
217 		eem->port.cdc_filter = DEFAULT_FILTER;
218 		DBG(cdev, "activate eem\n");
219 		net = gether_connect(&eem->port);
220 		if (IS_ERR(net))
221 			return PTR_ERR(net);
222 	} else
223 		goto fail;
224 
225 	return 0;
226 fail:
227 	return -EINVAL;
228 }
229 
eem_disable(struct usb_function * f)230 static void eem_disable(struct usb_function *f)
231 {
232 	struct f_eem		*eem = func_to_eem(f);
233 	struct usb_composite_dev *cdev = f->config->cdev;
234 
235 	DBG(cdev, "eem deactivated\n");
236 
237 	if (eem->port.in_ep->enabled)
238 		gether_disconnect(&eem->port);
239 }
240 
241 /*-------------------------------------------------------------------------*/
242 
243 /* EEM function driver setup/binding */
244 
eem_bind(struct usb_configuration * c,struct usb_function * f)245 static int eem_bind(struct usb_configuration *c, struct usb_function *f)
246 {
247 	struct usb_composite_dev *cdev = c->cdev;
248 	struct f_eem		*eem = func_to_eem(f);
249 	struct usb_string	*us;
250 	int			status;
251 	struct usb_ep		*ep;
252 
253 	struct f_eem_opts	*eem_opts;
254 
255 	eem_opts = container_of(f->fi, struct f_eem_opts, func_inst);
256 	/*
257 	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
258 	 * configurations are bound in sequence with list_for_each_entry,
259 	 * in each configuration its functions are bound in sequence
260 	 * with list_for_each_entry, so we assume no race condition
261 	 * with regard to eem_opts->bound access
262 	 */
263 	if (!eem_opts->bound) {
264 		mutex_lock(&eem_opts->lock);
265 		gether_set_gadget(eem_opts->net, cdev->gadget);
266 		status = gether_register_netdev(eem_opts->net);
267 		mutex_unlock(&eem_opts->lock);
268 		if (status)
269 			return status;
270 		eem_opts->bound = true;
271 	}
272 
273 	us = usb_gstrings_attach(cdev, eem_strings,
274 				 ARRAY_SIZE(eem_string_defs));
275 	if (IS_ERR(us))
276 		return PTR_ERR(us);
277 	eem_intf.iInterface = us[0].id;
278 
279 	/* allocate instance-specific interface IDs */
280 	status = usb_interface_id(c, f);
281 	if (status < 0)
282 		goto fail;
283 	eem->ctrl_id = status;
284 	eem_intf.bInterfaceNumber = status;
285 
286 	status = -ENODEV;
287 
288 	/* allocate instance-specific endpoints */
289 	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_in_desc);
290 	if (!ep)
291 		goto fail;
292 	eem->port.in_ep = ep;
293 
294 	ep = usb_ep_autoconfig(cdev->gadget, &eem_fs_out_desc);
295 	if (!ep)
296 		goto fail;
297 	eem->port.out_ep = ep;
298 
299 	/* support all relevant hardware speeds... we expect that when
300 	 * hardware is dual speed, all bulk-capable endpoints work at
301 	 * both speeds
302 	 */
303 	eem_hs_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
304 	eem_hs_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
305 
306 	eem_ss_in_desc.bEndpointAddress = eem_fs_in_desc.bEndpointAddress;
307 	eem_ss_out_desc.bEndpointAddress = eem_fs_out_desc.bEndpointAddress;
308 
309 	status = usb_assign_descriptors(f, eem_fs_function, eem_hs_function,
310 			eem_ss_function, eem_ss_function);
311 	if (status)
312 		goto fail;
313 
314 	DBG(cdev, "CDC Ethernet (EEM): IN/%s OUT/%s\n",
315 			eem->port.in_ep->name, eem->port.out_ep->name);
316 	return 0;
317 
318 fail:
319 	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
320 
321 	return status;
322 }
323 
eem_cmd_complete(struct usb_ep * ep,struct usb_request * req)324 static void eem_cmd_complete(struct usb_ep *ep, struct usb_request *req)
325 {
326 	struct in_context *ctx = req->context;
327 
328 	dev_kfree_skb_any(ctx->skb);
329 	kfree(req->buf);
330 	usb_ep_free_request(ctx->ep, req);
331 	kfree(ctx);
332 }
333 
334 /*
335  * Add the EEM header and ethernet checksum.
336  * We currently do not attempt to put multiple ethernet frames
337  * into a single USB transfer
338  */
eem_wrap(struct gether * port,struct sk_buff * skb)339 static struct sk_buff *eem_wrap(struct gether *port, struct sk_buff *skb)
340 {
341 	struct sk_buff	*skb2 = NULL;
342 	struct usb_ep	*in = port->in_ep;
343 	int		headroom, tailroom, padlen = 0;
344 	u16		len;
345 
346 	if (!skb)
347 		return NULL;
348 
349 	len = skb->len;
350 	headroom = skb_headroom(skb);
351 	tailroom = skb_tailroom(skb);
352 
353 	/* When (len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) is 0,
354 	 * stick two bytes of zero-length EEM packet on the end.
355 	 */
356 	if (((len + EEM_HLEN + ETH_FCS_LEN) % in->maxpacket) == 0)
357 		padlen += 2;
358 
359 	if ((tailroom >= (ETH_FCS_LEN + padlen)) &&
360 			(headroom >= EEM_HLEN) && !skb_cloned(skb))
361 		goto done;
362 
363 	skb2 = skb_copy_expand(skb, EEM_HLEN, ETH_FCS_LEN + padlen, GFP_ATOMIC);
364 	dev_kfree_skb_any(skb);
365 	skb = skb2;
366 	if (!skb)
367 		return skb;
368 
369 done:
370 	/* use the "no CRC" option */
371 	put_unaligned_be32(0xdeadbeef, skb_put(skb, 4));
372 
373 	/* EEM packet header format:
374 	 * b0..13:	length of ethernet frame
375 	 * b14:		bmCRC (0 == sentinel CRC)
376 	 * b15:		bmType (0 == data)
377 	 */
378 	len = skb->len;
379 	put_unaligned_le16(len & 0x3FFF, skb_push(skb, 2));
380 
381 	/* add a zero-length EEM packet, if needed */
382 	if (padlen)
383 		put_unaligned_le16(0, skb_put(skb, 2));
384 
385 	return skb;
386 }
387 
388 /*
389  * Remove the EEM header.  Note that there can be many EEM packets in a single
390  * USB transfer, so we need to break them out and handle them independently.
391  */
eem_unwrap(struct gether * port,struct sk_buff * skb,struct sk_buff_head * list)392 static int eem_unwrap(struct gether *port,
393 			struct sk_buff *skb,
394 			struct sk_buff_head *list)
395 {
396 	struct usb_composite_dev	*cdev = port->func.config->cdev;
397 	int				status = 0;
398 
399 	do {
400 		struct sk_buff	*skb2;
401 		u16		header;
402 		u16		len = 0;
403 
404 		if (skb->len < EEM_HLEN) {
405 			status = -EINVAL;
406 			DBG(cdev, "invalid EEM header\n");
407 			goto error;
408 		}
409 
410 		/* remove the EEM header */
411 		header = get_unaligned_le16(skb->data);
412 		skb_pull(skb, EEM_HLEN);
413 
414 		/* EEM packet header format:
415 		 * b0..14:	EEM type dependent (data or command)
416 		 * b15:		bmType (0 == data, 1 == command)
417 		 */
418 		if (header & BIT(15)) {
419 			struct usb_request	*req;
420 			struct in_context	*ctx;
421 			struct usb_ep		*ep;
422 			u16			bmEEMCmd;
423 
424 			/* EEM command packet format:
425 			 * b0..10:	bmEEMCmdParam
426 			 * b11..13:	bmEEMCmd
427 			 * b14:		reserved (must be zero)
428 			 * b15:		bmType (1 == command)
429 			 */
430 			if (header & BIT(14))
431 				continue;
432 
433 			bmEEMCmd = (header >> 11) & 0x7;
434 			switch (bmEEMCmd) {
435 			case 0: /* echo */
436 				len = header & 0x7FF;
437 				if (skb->len < len) {
438 					status = -EOVERFLOW;
439 					goto error;
440 				}
441 
442 				skb2 = skb_clone(skb, GFP_ATOMIC);
443 				if (unlikely(!skb2)) {
444 					DBG(cdev, "EEM echo response error\n");
445 					goto next;
446 				}
447 				skb_trim(skb2, len);
448 				put_unaligned_le16(BIT(15) | BIT(11) | len,
449 							skb_push(skb2, 2));
450 
451 				ep = port->in_ep;
452 				req = usb_ep_alloc_request(ep, GFP_ATOMIC);
453 				if (!req) {
454 					dev_kfree_skb_any(skb2);
455 					goto next;
456 				}
457 
458 				req->buf = kmalloc(skb2->len, GFP_KERNEL);
459 				if (!req->buf) {
460 					usb_ep_free_request(ep, req);
461 					dev_kfree_skb_any(skb2);
462 					goto next;
463 				}
464 
465 				ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
466 				if (!ctx) {
467 					kfree(req->buf);
468 					usb_ep_free_request(ep, req);
469 					dev_kfree_skb_any(skb2);
470 					goto next;
471 				}
472 				ctx->skb = skb2;
473 				ctx->ep = ep;
474 
475 				skb_copy_bits(skb2, 0, req->buf, skb2->len);
476 				req->length = skb2->len;
477 				req->complete = eem_cmd_complete;
478 				req->zero = 1;
479 				req->context = ctx;
480 				if (usb_ep_queue(port->in_ep, req, GFP_ATOMIC))
481 					DBG(cdev, "echo response queue fail\n");
482 				break;
483 
484 			case 1:  /* echo response */
485 			case 2:  /* suspend hint */
486 			case 3:  /* response hint */
487 			case 4:  /* response complete hint */
488 			case 5:  /* tickle */
489 			default: /* reserved */
490 				continue;
491 			}
492 		} else {
493 			u32		crc, crc2;
494 			struct sk_buff	*skb3;
495 
496 			/* check for zero-length EEM packet */
497 			if (header == 0)
498 				continue;
499 
500 			/* EEM data packet format:
501 			 * b0..13:	length of ethernet frame
502 			 * b14:		bmCRC (0 == sentinel, 1 == calculated)
503 			 * b15:		bmType (0 == data)
504 			 */
505 			len = header & 0x3FFF;
506 			if ((skb->len < len)
507 					|| (len < (ETH_HLEN + ETH_FCS_LEN))) {
508 				status = -EINVAL;
509 				goto error;
510 			}
511 
512 			/* validate CRC */
513 			if (header & BIT(14)) {
514 				crc = get_unaligned_le32(skb->data + len
515 							- ETH_FCS_LEN);
516 				crc2 = ~crc32_le(~0,
517 						skb->data, len - ETH_FCS_LEN);
518 			} else {
519 				crc = get_unaligned_be32(skb->data + len
520 							- ETH_FCS_LEN);
521 				crc2 = 0xdeadbeef;
522 			}
523 			if (crc != crc2) {
524 				DBG(cdev, "invalid EEM CRC\n");
525 				goto next;
526 			}
527 
528 			skb2 = skb_clone(skb, GFP_ATOMIC);
529 			if (unlikely(!skb2)) {
530 				DBG(cdev, "unable to unframe EEM packet\n");
531 				goto next;
532 			}
533 			skb_trim(skb2, len - ETH_FCS_LEN);
534 
535 			skb3 = skb_copy_expand(skb2,
536 						NET_IP_ALIGN,
537 						0,
538 						GFP_ATOMIC);
539 			if (unlikely(!skb3)) {
540 				dev_kfree_skb_any(skb2);
541 				goto next;
542 			}
543 			dev_kfree_skb_any(skb2);
544 			skb_queue_tail(list, skb3);
545 		}
546 next:
547 		skb_pull(skb, len);
548 	} while (skb->len);
549 
550 error:
551 	dev_kfree_skb_any(skb);
552 	return status;
553 }
554 
to_f_eem_opts(struct config_item * item)555 static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
556 {
557 	return container_of(to_config_group(item), struct f_eem_opts,
558 			    func_inst.group);
559 }
560 
561 /* f_eem_item_ops */
562 USB_ETHERNET_CONFIGFS_ITEM(eem);
563 
564 /* f_eem_opts_dev_addr */
565 USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
566 
567 /* f_eem_opts_host_addr */
568 USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
569 
570 /* f_eem_opts_qmult */
571 USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
572 
573 /* f_eem_opts_ifname */
574 USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
575 
576 static struct configfs_attribute *eem_attrs[] = {
577 	&eem_opts_attr_dev_addr,
578 	&eem_opts_attr_host_addr,
579 	&eem_opts_attr_qmult,
580 	&eem_opts_attr_ifname,
581 	NULL,
582 };
583 
584 static const struct config_item_type eem_func_type = {
585 	.ct_item_ops	= &eem_item_ops,
586 	.ct_attrs	= eem_attrs,
587 	.ct_owner	= THIS_MODULE,
588 };
589 
eem_free_inst(struct usb_function_instance * f)590 static void eem_free_inst(struct usb_function_instance *f)
591 {
592 	struct f_eem_opts *opts;
593 
594 	opts = container_of(f, struct f_eem_opts, func_inst);
595 	if (opts->bound)
596 		gether_cleanup(netdev_priv(opts->net));
597 	else
598 		free_netdev(opts->net);
599 	kfree(opts);
600 }
601 
eem_alloc_inst(void)602 static struct usb_function_instance *eem_alloc_inst(void)
603 {
604 	struct f_eem_opts *opts;
605 
606 	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
607 	if (!opts)
608 		return ERR_PTR(-ENOMEM);
609 	mutex_init(&opts->lock);
610 	opts->func_inst.free_func_inst = eem_free_inst;
611 	opts->net = gether_setup_default();
612 	if (IS_ERR(opts->net)) {
613 		struct net_device *net = opts->net;
614 		kfree(opts);
615 		return ERR_CAST(net);
616 	}
617 
618 	config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
619 
620 	return &opts->func_inst;
621 }
622 
eem_free(struct usb_function * f)623 static void eem_free(struct usb_function *f)
624 {
625 	struct f_eem *eem;
626 	struct f_eem_opts *opts;
627 
628 	eem = func_to_eem(f);
629 	opts = container_of(f->fi, struct f_eem_opts, func_inst);
630 	kfree(eem);
631 	mutex_lock(&opts->lock);
632 	opts->refcnt--;
633 	mutex_unlock(&opts->lock);
634 }
635 
eem_unbind(struct usb_configuration * c,struct usb_function * f)636 static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
637 {
638 	DBG(c->cdev, "eem unbind\n");
639 
640 	usb_free_all_descriptors(f);
641 }
642 
eem_alloc(struct usb_function_instance * fi)643 static struct usb_function *eem_alloc(struct usb_function_instance *fi)
644 {
645 	struct f_eem	*eem;
646 	struct f_eem_opts *opts;
647 
648 	/* allocate and initialize one new instance */
649 	eem = kzalloc(sizeof(*eem), GFP_KERNEL);
650 	if (!eem)
651 		return ERR_PTR(-ENOMEM);
652 
653 	opts = container_of(fi, struct f_eem_opts, func_inst);
654 	mutex_lock(&opts->lock);
655 	opts->refcnt++;
656 
657 	eem->port.ioport = netdev_priv(opts->net);
658 	mutex_unlock(&opts->lock);
659 	eem->port.cdc_filter = DEFAULT_FILTER;
660 
661 	eem->port.func.name = "cdc_eem";
662 	/* descriptors are per-instance copies */
663 	eem->port.func.bind = eem_bind;
664 	eem->port.func.unbind = eem_unbind;
665 	eem->port.func.set_alt = eem_set_alt;
666 	eem->port.func.setup = eem_setup;
667 	eem->port.func.disable = eem_disable;
668 	eem->port.func.free_func = eem_free;
669 	eem->port.wrap = eem_wrap;
670 	eem->port.unwrap = eem_unwrap;
671 	eem->port.header_len = EEM_HLEN;
672 
673 	return &eem->port.func;
674 }
675 
676 DECLARE_USB_FUNCTION_INIT(eem, eem_alloc_inst, eem_alloc);
677 MODULE_LICENSE("GPL");
678 MODULE_AUTHOR("David Brownell");
679