1// SPDX-License-Identifier: GPL-2.0
2/*
3 * f_phonet.c -- USB CDC Phonet function
4 *
5 * Copyright (C) 2007-2008 Nokia Corporation. All rights reserved.
6 *
7 * Author: Rémi Denis-Courmont
8 */
9
10#include <linux/mm.h>
11#include <linux/slab.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/device.h>
15
16#include <linux/netdevice.h>
17#include <linux/if_ether.h>
18#include <linux/if_phonet.h>
19#include <linux/if_arp.h>
20
21#include <linux/usb/ch9.h>
22#include <linux/usb/cdc.h>
23#include <linux/usb/composite.h>
24
25#include "u_phonet.h"
26#include "u_ether.h"
27
28#define PN_MEDIA_USB 0x1B
29#define MAXPACKET 512
30#if (PAGE_SIZE % MAXPACKET)
31#error MAXPACKET must divide PAGE_SIZE!
32#endif
33
34/*-------------------------------------------------------------------------*/
35
36struct phonet_port {
37 struct f_phonet *usb;
38 spinlock_t lock;
39};
40
41struct f_phonet {
42 struct usb_function function;
43 struct {
44 struct sk_buff *skb;
45 spinlock_t lock;
46 } rx;
47 struct net_device *dev;
48 struct usb_ep *in_ep, *out_ep;
49
50 struct usb_request *in_req;
51 struct usb_request *out_reqv[];
52};
53
54static int phonet_rxq_size = 17;
55
56static inline struct f_phonet *func_to_pn(struct usb_function *f)
57{
58 return container_of(f, struct f_phonet, function);
59}
60
61/*-------------------------------------------------------------------------*/
62
63#define USB_CDC_SUBCLASS_PHONET 0xfe
64#define USB_CDC_PHONET_TYPE 0xab
65
66static struct usb_interface_descriptor
67pn_control_intf_desc = {
68 .bLength = sizeof pn_control_intf_desc,
69 .bDescriptorType = USB_DT_INTERFACE,
70
71 /* .bInterfaceNumber = DYNAMIC, */
72 .bInterfaceClass = USB_CLASS_COMM,
73 .bInterfaceSubClass = USB_CDC_SUBCLASS_PHONET,
74};
75
76static const struct usb_cdc_header_desc
77pn_header_desc = {
78 .bLength = sizeof pn_header_desc,
79 .bDescriptorType = USB_DT_CS_INTERFACE,
80 .bDescriptorSubType = USB_CDC_HEADER_TYPE,
81 .bcdCDC = cpu_to_le16(0x0110),
82};
83
84static const struct usb_cdc_header_desc
85pn_phonet_desc = {
86 .bLength = sizeof pn_phonet_desc,
87 .bDescriptorType = USB_DT_CS_INTERFACE,
88 .bDescriptorSubType = USB_CDC_PHONET_TYPE,
89 .bcdCDC = cpu_to_le16(0x1505), /* ??? */
90};
91
92static struct usb_cdc_union_desc
93pn_union_desc = {
94 .bLength = sizeof pn_union_desc,
95 .bDescriptorType = USB_DT_CS_INTERFACE,
96 .bDescriptorSubType = USB_CDC_UNION_TYPE,
97
98 /* .bMasterInterface0 = DYNAMIC, */
99 /* .bSlaveInterface0 = DYNAMIC, */
100};
101
102static struct usb_interface_descriptor
103pn_data_nop_intf_desc = {
104 .bLength = sizeof pn_data_nop_intf_desc,
105 .bDescriptorType = USB_DT_INTERFACE,
106
107 /* .bInterfaceNumber = DYNAMIC, */
108 .bAlternateSetting = 0,
109 .bNumEndpoints = 0,
110 .bInterfaceClass = USB_CLASS_CDC_DATA,
111};
112
113static struct usb_interface_descriptor
114pn_data_intf_desc = {
115 .bLength = sizeof pn_data_intf_desc,
116 .bDescriptorType = USB_DT_INTERFACE,
117
118 /* .bInterfaceNumber = DYNAMIC, */
119 .bAlternateSetting = 1,
120 .bNumEndpoints = 2,
121 .bInterfaceClass = USB_CLASS_CDC_DATA,
122};
123
124static struct usb_endpoint_descriptor
125pn_fs_sink_desc = {
126 .bLength = USB_DT_ENDPOINT_SIZE,
127 .bDescriptorType = USB_DT_ENDPOINT,
128
129 .bEndpointAddress = USB_DIR_OUT,
130 .bmAttributes = USB_ENDPOINT_XFER_BULK,
131};
132
133static struct usb_endpoint_descriptor
134pn_hs_sink_desc = {
135 .bLength = USB_DT_ENDPOINT_SIZE,
136 .bDescriptorType = USB_DT_ENDPOINT,
137
138 .bEndpointAddress = USB_DIR_OUT,
139 .bmAttributes = USB_ENDPOINT_XFER_BULK,
140 .wMaxPacketSize = cpu_to_le16(MAXPACKET),
141};
142
143static struct usb_endpoint_descriptor
144pn_fs_source_desc = {
145 .bLength = USB_DT_ENDPOINT_SIZE,
146 .bDescriptorType = USB_DT_ENDPOINT,
147
148 .bEndpointAddress = USB_DIR_IN,
149 .bmAttributes = USB_ENDPOINT_XFER_BULK,
150};
151
152static struct usb_endpoint_descriptor
153pn_hs_source_desc = {
154 .bLength = USB_DT_ENDPOINT_SIZE,
155 .bDescriptorType = USB_DT_ENDPOINT,
156
157 .bEndpointAddress = USB_DIR_IN,
158 .bmAttributes = USB_ENDPOINT_XFER_BULK,
159 .wMaxPacketSize = cpu_to_le16(512),
160};
161
162static struct usb_descriptor_header *fs_pn_function[] = {
163 (struct usb_descriptor_header *) &pn_control_intf_desc,
164 (struct usb_descriptor_header *) &pn_header_desc,
165 (struct usb_descriptor_header *) &pn_phonet_desc,
166 (struct usb_descriptor_header *) &pn_union_desc,
167 (struct usb_descriptor_header *) &pn_data_nop_intf_desc,
168 (struct usb_descriptor_header *) &pn_data_intf_desc,
169 (struct usb_descriptor_header *) &pn_fs_sink_desc,
170 (struct usb_descriptor_header *) &pn_fs_source_desc,
171 NULL,
172};
173
174static struct usb_descriptor_header *hs_pn_function[] = {
175 (struct usb_descriptor_header *) &pn_control_intf_desc,
176 (struct usb_descriptor_header *) &pn_header_desc,
177 (struct usb_descriptor_header *) &pn_phonet_desc,
178 (struct usb_descriptor_header *) &pn_union_desc,
179 (struct usb_descriptor_header *) &pn_data_nop_intf_desc,
180 (struct usb_descriptor_header *) &pn_data_intf_desc,
181 (struct usb_descriptor_header *) &pn_hs_sink_desc,
182 (struct usb_descriptor_header *) &pn_hs_source_desc,
183 NULL,
184};
185
186/*-------------------------------------------------------------------------*/
187
188static int pn_net_open(struct net_device *dev)
189{
190 netif_wake_queue(dev);
191 return 0;
192}
193
194static int pn_net_close(struct net_device *dev)
195{
196 netif_stop_queue(dev);
197 return 0;
198}
199
200static void pn_tx_complete(struct usb_ep *ep, struct usb_request *req)
201{
202 struct f_phonet *fp = ep->driver_data;
203 struct net_device *dev = fp->dev;
204 struct sk_buff *skb = req->context;
205
206 switch (req->status) {
207 case 0:
208 dev->stats.tx_packets++;
209 dev->stats.tx_bytes += skb->len;
210 break;
211
212 case -ESHUTDOWN: /* disconnected */
213 case -ECONNRESET: /* disabled */
214 dev->stats.tx_aborted_errors++;
215 fallthrough;
216 default:
217 dev->stats.tx_errors++;
218 }
219
220 dev_kfree_skb_any(skb);
221 netif_wake_queue(dev);
222}
223
224static netdev_tx_t pn_net_xmit(struct sk_buff *skb, struct net_device *dev)
225{
226 struct phonet_port *port = netdev_priv(dev);
227 struct f_phonet *fp;
228 struct usb_request *req;
229 unsigned long flags;
230
231 if (skb->protocol != htons(ETH_P_PHONET))
232 goto out;
233
234 spin_lock_irqsave(&port->lock, flags);
235 fp = port->usb;
236 if (unlikely(!fp)) /* race with carrier loss */
237 goto out_unlock;
238
239 req = fp->in_req;
240 req->buf = skb->data;
241 req->length = skb->len;
242 req->complete = pn_tx_complete;
243 req->zero = 1;
244 req->context = skb;
245
246 if (unlikely(usb_ep_queue(fp->in_ep, req, GFP_ATOMIC)))
247 goto out_unlock;
248
249 netif_stop_queue(dev);
250 skb = NULL;
251
252out_unlock:
253 spin_unlock_irqrestore(lock: &port->lock, flags);
254out:
255 if (unlikely(skb)) {
256 dev_kfree_skb(skb);
257 dev->stats.tx_dropped++;
258 }
259 return NETDEV_TX_OK;
260}
261
262static const struct net_device_ops pn_netdev_ops = {
263 .ndo_open = pn_net_open,
264 .ndo_stop = pn_net_close,
265 .ndo_start_xmit = pn_net_xmit,
266};
267
268static void pn_net_setup(struct net_device *dev)
269{
270 const u8 addr = PN_MEDIA_USB;
271
272 dev->features = 0;
273 dev->type = ARPHRD_PHONET;
274 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
275 dev->mtu = PHONET_DEV_MTU;
276 dev->min_mtu = PHONET_MIN_MTU;
277 dev->max_mtu = PHONET_MAX_MTU;
278 dev->hard_header_len = 1;
279 dev->addr_len = 1;
280 dev_addr_set(dev, addr: &addr);
281
282 dev->tx_queue_len = 1;
283
284 dev->netdev_ops = &pn_netdev_ops;
285 dev->needs_free_netdev = true;
286 dev->header_ops = &phonet_header_ops;
287}
288
289/*-------------------------------------------------------------------------*/
290
291/*
292 * Queue buffer for data from the host
293 */
294static int
295pn_rx_submit(struct f_phonet *fp, struct usb_request *req, gfp_t gfp_flags)
296{
297 struct page *page;
298 int err;
299
300 page = __dev_alloc_page(gfp_flags | __GFP_NOMEMALLOC);
301 if (!page)
302 return -ENOMEM;
303
304 req->buf = page_address(page);
305 req->length = PAGE_SIZE;
306 req->context = page;
307
308 err = usb_ep_queue(ep: fp->out_ep, req, gfp_flags);
309 if (unlikely(err))
310 put_page(page);
311 return err;
312}
313
314static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req)
315{
316 struct f_phonet *fp = ep->driver_data;
317 struct net_device *dev = fp->dev;
318 struct page *page = req->context;
319 struct sk_buff *skb;
320 unsigned long flags;
321 int status = req->status;
322
323 switch (status) {
324 case 0:
325 spin_lock_irqsave(&fp->rx.lock, flags);
326 skb = fp->rx.skb;
327 if (!skb)
328 skb = fp->rx.skb = netdev_alloc_skb(dev, length: 12);
329 if (req->actual < req->length) /* Last fragment */
330 fp->rx.skb = NULL;
331 spin_unlock_irqrestore(lock: &fp->rx.lock, flags);
332
333 if (unlikely(!skb))
334 break;
335
336 if (skb->len == 0) { /* First fragment */
337 skb->protocol = htons(ETH_P_PHONET);
338 skb_reset_mac_header(skb);
339 /* Can't use pskb_pull() on page in IRQ */
340 skb_put_data(skb, page_address(page), len: 1);
341 }
342
343 skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
344 off: skb->len <= 1, size: req->actual, PAGE_SIZE);
345 page = NULL;
346
347 if (req->actual < req->length) { /* Last fragment */
348 skb->dev = dev;
349 dev->stats.rx_packets++;
350 dev->stats.rx_bytes += skb->len;
351
352 netif_rx(skb);
353 }
354 break;
355
356 /* Do not resubmit in these cases: */
357 case -ESHUTDOWN: /* disconnect */
358 case -ECONNABORTED: /* hw reset */
359 case -ECONNRESET: /* dequeued (unlink or netif down) */
360 req = NULL;
361 break;
362
363 /* Do resubmit in these cases: */
364 case -EOVERFLOW: /* request buffer overflow */
365 dev->stats.rx_over_errors++;
366 fallthrough;
367 default:
368 dev->stats.rx_errors++;
369 break;
370 }
371
372 if (page)
373 put_page(page);
374 if (req)
375 pn_rx_submit(fp, req, GFP_ATOMIC);
376}
377
378/*-------------------------------------------------------------------------*/
379
380static void __pn_reset(struct usb_function *f)
381{
382 struct f_phonet *fp = func_to_pn(f);
383 struct net_device *dev = fp->dev;
384 struct phonet_port *port = netdev_priv(dev);
385
386 netif_carrier_off(dev);
387 port->usb = NULL;
388
389 usb_ep_disable(ep: fp->out_ep);
390 usb_ep_disable(ep: fp->in_ep);
391 if (fp->rx.skb) {
392 dev_kfree_skb_irq(skb: fp->rx.skb);
393 fp->rx.skb = NULL;
394 }
395}
396
397static int pn_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
398{
399 struct f_phonet *fp = func_to_pn(f);
400 struct usb_gadget *gadget = fp->function.config->cdev->gadget;
401
402 if (intf == pn_control_intf_desc.bInterfaceNumber)
403 /* control interface, no altsetting */
404 return (alt > 0) ? -EINVAL : 0;
405
406 if (intf == pn_data_intf_desc.bInterfaceNumber) {
407 struct net_device *dev = fp->dev;
408 struct phonet_port *port = netdev_priv(dev);
409
410 /* data intf (0: inactive, 1: active) */
411 if (alt > 1)
412 return -EINVAL;
413
414 spin_lock(lock: &port->lock);
415
416 if (fp->in_ep->enabled)
417 __pn_reset(f);
418
419 if (alt == 1) {
420 int i;
421
422 if (config_ep_by_speed(g: gadget, f, ep: fp->in_ep) ||
423 config_ep_by_speed(g: gadget, f, ep: fp->out_ep)) {
424 fp->in_ep->desc = NULL;
425 fp->out_ep->desc = NULL;
426 spin_unlock(lock: &port->lock);
427 return -EINVAL;
428 }
429 usb_ep_enable(ep: fp->out_ep);
430 usb_ep_enable(ep: fp->in_ep);
431
432 port->usb = fp;
433 fp->out_ep->driver_data = fp;
434 fp->in_ep->driver_data = fp;
435
436 netif_carrier_on(dev);
437 for (i = 0; i < phonet_rxq_size; i++)
438 pn_rx_submit(fp, req: fp->out_reqv[i], GFP_ATOMIC);
439 }
440 spin_unlock(lock: &port->lock);
441 return 0;
442 }
443
444 return -EINVAL;
445}
446
447static int pn_get_alt(struct usb_function *f, unsigned intf)
448{
449 struct f_phonet *fp = func_to_pn(f);
450
451 if (intf == pn_control_intf_desc.bInterfaceNumber)
452 return 0;
453
454 if (intf == pn_data_intf_desc.bInterfaceNumber) {
455 struct phonet_port *port = netdev_priv(dev: fp->dev);
456 u8 alt;
457
458 spin_lock(lock: &port->lock);
459 alt = port->usb != NULL;
460 spin_unlock(lock: &port->lock);
461 return alt;
462 }
463
464 return -EINVAL;
465}
466
467static void pn_disconnect(struct usb_function *f)
468{
469 struct f_phonet *fp = func_to_pn(f);
470 struct phonet_port *port = netdev_priv(dev: fp->dev);
471 unsigned long flags;
472
473 /* remain disabled until set_alt */
474 spin_lock_irqsave(&port->lock, flags);
475 __pn_reset(f);
476 spin_unlock_irqrestore(lock: &port->lock, flags);
477}
478
479/*-------------------------------------------------------------------------*/
480
481static int pn_bind(struct usb_configuration *c, struct usb_function *f)
482{
483 struct usb_composite_dev *cdev = c->cdev;
484 struct usb_gadget *gadget = cdev->gadget;
485 struct f_phonet *fp = func_to_pn(f);
486 struct usb_ep *ep;
487 int status, i;
488
489 struct f_phonet_opts *phonet_opts;
490
491 phonet_opts = container_of(f->fi, struct f_phonet_opts, func_inst);
492
493 /*
494 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
495 * configurations are bound in sequence with list_for_each_entry,
496 * in each configuration its functions are bound in sequence
497 * with list_for_each_entry, so we assume no race condition
498 * with regard to phonet_opts->bound access
499 */
500 if (!phonet_opts->bound) {
501 gphonet_set_gadget(net: phonet_opts->net, g: gadget);
502 status = gphonet_register_netdev(net: phonet_opts->net);
503 if (status)
504 return status;
505 phonet_opts->bound = true;
506 }
507
508 /* Reserve interface IDs */
509 status = usb_interface_id(c, f);
510 if (status < 0)
511 goto err;
512 pn_control_intf_desc.bInterfaceNumber = status;
513 pn_union_desc.bMasterInterface0 = status;
514
515 status = usb_interface_id(c, f);
516 if (status < 0)
517 goto err;
518 pn_data_nop_intf_desc.bInterfaceNumber = status;
519 pn_data_intf_desc.bInterfaceNumber = status;
520 pn_union_desc.bSlaveInterface0 = status;
521
522 /* Reserve endpoints */
523 status = -ENODEV;
524 ep = usb_ep_autoconfig(gadget, &pn_fs_sink_desc);
525 if (!ep)
526 goto err;
527 fp->out_ep = ep;
528
529 ep = usb_ep_autoconfig(gadget, &pn_fs_source_desc);
530 if (!ep)
531 goto err;
532 fp->in_ep = ep;
533
534 pn_hs_sink_desc.bEndpointAddress = pn_fs_sink_desc.bEndpointAddress;
535 pn_hs_source_desc.bEndpointAddress = pn_fs_source_desc.bEndpointAddress;
536
537 /* Do not try to bind Phonet twice... */
538 status = usb_assign_descriptors(f, fs: fs_pn_function, hs: hs_pn_function,
539 NULL, NULL);
540 if (status)
541 goto err;
542
543 /* Incoming USB requests */
544 status = -ENOMEM;
545 for (i = 0; i < phonet_rxq_size; i++) {
546 struct usb_request *req;
547
548 req = usb_ep_alloc_request(ep: fp->out_ep, GFP_KERNEL);
549 if (!req)
550 goto err_req;
551
552 req->complete = pn_rx_complete;
553 fp->out_reqv[i] = req;
554 }
555
556 /* Outgoing USB requests */
557 fp->in_req = usb_ep_alloc_request(ep: fp->in_ep, GFP_KERNEL);
558 if (!fp->in_req)
559 goto err_req;
560
561 INFO(cdev, "USB CDC Phonet function\n");
562 INFO(cdev, "using %s, OUT %s, IN %s\n", cdev->gadget->name,
563 fp->out_ep->name, fp->in_ep->name);
564 return 0;
565
566err_req:
567 for (i = 0; i < phonet_rxq_size && fp->out_reqv[i]; i++)
568 usb_ep_free_request(ep: fp->out_ep, req: fp->out_reqv[i]);
569 usb_free_all_descriptors(f);
570err:
571 ERROR(cdev, "USB CDC Phonet: cannot autoconfigure\n");
572 return status;
573}
574
575static inline struct f_phonet_opts *to_f_phonet_opts(struct config_item *item)
576{
577 return container_of(to_config_group(item), struct f_phonet_opts,
578 func_inst.group);
579}
580
581static void phonet_attr_release(struct config_item *item)
582{
583 struct f_phonet_opts *opts = to_f_phonet_opts(item);
584
585 usb_put_function_instance(fi: &opts->func_inst);
586}
587
588static struct configfs_item_operations phonet_item_ops = {
589 .release = phonet_attr_release,
590};
591
592static ssize_t f_phonet_ifname_show(struct config_item *item, char *page)
593{
594 return gether_get_ifname(net: to_f_phonet_opts(item)->net, name: page, PAGE_SIZE);
595}
596
597CONFIGFS_ATTR_RO(f_phonet_, ifname);
598
599static struct configfs_attribute *phonet_attrs[] = {
600 &f_phonet_attr_ifname,
601 NULL,
602};
603
604static const struct config_item_type phonet_func_type = {
605 .ct_item_ops = &phonet_item_ops,
606 .ct_attrs = phonet_attrs,
607 .ct_owner = THIS_MODULE,
608};
609
610static void phonet_free_inst(struct usb_function_instance *f)
611{
612 struct f_phonet_opts *opts;
613
614 opts = container_of(f, struct f_phonet_opts, func_inst);
615 if (opts->bound)
616 gphonet_cleanup(dev: opts->net);
617 else
618 free_netdev(dev: opts->net);
619 kfree(objp: opts);
620}
621
622static struct usb_function_instance *phonet_alloc_inst(void)
623{
624 struct f_phonet_opts *opts;
625
626 opts = kzalloc(sizeof(*opts), GFP_KERNEL);
627 if (!opts)
628 return ERR_PTR(error: -ENOMEM);
629
630 opts->func_inst.free_func_inst = phonet_free_inst;
631 opts->net = gphonet_setup_default();
632 if (IS_ERR(ptr: opts->net)) {
633 struct net_device *net = opts->net;
634 kfree(objp: opts);
635 return ERR_CAST(ptr: net);
636 }
637
638 config_group_init_type_name(group: &opts->func_inst.group, name: "",
639 type: &phonet_func_type);
640
641 return &opts->func_inst;
642}
643
644static void phonet_free(struct usb_function *f)
645{
646 struct f_phonet *phonet;
647
648 phonet = func_to_pn(f);
649 kfree(objp: phonet);
650}
651
652static void pn_unbind(struct usb_configuration *c, struct usb_function *f)
653{
654 struct f_phonet *fp = func_to_pn(f);
655 int i;
656
657 /* We are already disconnected */
658 if (fp->in_req)
659 usb_ep_free_request(ep: fp->in_ep, req: fp->in_req);
660 for (i = 0; i < phonet_rxq_size; i++)
661 if (fp->out_reqv[i])
662 usb_ep_free_request(ep: fp->out_ep, req: fp->out_reqv[i]);
663
664 usb_free_all_descriptors(f);
665}
666
667static struct usb_function *phonet_alloc(struct usb_function_instance *fi)
668{
669 struct f_phonet *fp;
670 struct f_phonet_opts *opts;
671
672 fp = kzalloc(struct_size(fp, out_reqv, phonet_rxq_size), GFP_KERNEL);
673 if (!fp)
674 return ERR_PTR(error: -ENOMEM);
675
676 opts = container_of(fi, struct f_phonet_opts, func_inst);
677
678 fp->dev = opts->net;
679 fp->function.name = "phonet";
680 fp->function.bind = pn_bind;
681 fp->function.unbind = pn_unbind;
682 fp->function.set_alt = pn_set_alt;
683 fp->function.get_alt = pn_get_alt;
684 fp->function.disable = pn_disconnect;
685 fp->function.free_func = phonet_free;
686 spin_lock_init(&fp->rx.lock);
687
688 return &fp->function;
689}
690
691struct net_device *gphonet_setup_default(void)
692{
693 struct net_device *dev;
694 struct phonet_port *port;
695
696 /* Create net device */
697 dev = alloc_netdev(sizeof(*port), "upnlink%d", NET_NAME_UNKNOWN,
698 pn_net_setup);
699 if (!dev)
700 return ERR_PTR(error: -ENOMEM);
701
702 port = netdev_priv(dev);
703 spin_lock_init(&port->lock);
704 netif_carrier_off(dev);
705
706 return dev;
707}
708
709void gphonet_set_gadget(struct net_device *net, struct usb_gadget *g)
710{
711 SET_NETDEV_DEV(net, &g->dev);
712}
713
714int gphonet_register_netdev(struct net_device *net)
715{
716 int status;
717
718 status = register_netdev(dev: net);
719 if (status)
720 free_netdev(dev: net);
721
722 return status;
723}
724
725void gphonet_cleanup(struct net_device *dev)
726{
727 unregister_netdev(dev);
728}
729
730DECLARE_USB_FUNCTION_INIT(phonet, phonet_alloc_inst, phonet_alloc);
731MODULE_AUTHOR("Rémi Denis-Courmont");
732MODULE_DESCRIPTION("USB CDC Phonet function");
733MODULE_LICENSE("GPL");
734

source code of linux/drivers/usb/gadget/function/f_phonet.c