xref: /openbmc/linux/drivers/usb/gadget/legacy/inode.c (revision a2818ee4)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * inode.c -- user mode filesystem api for usb gadget controllers
4  *
5  * Copyright (C) 2003-2004 David Brownell
6  * Copyright (C) 2003 Agilent Technologies
7  */
8 
9 
10 /* #define VERBOSE_DEBUG */
11 
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/fs.h>
15 #include <linux/pagemap.h>
16 #include <linux/uts.h>
17 #include <linux/wait.h>
18 #include <linux/compiler.h>
19 #include <linux/uaccess.h>
20 #include <linux/sched.h>
21 #include <linux/slab.h>
22 #include <linux/poll.h>
23 #include <linux/mmu_context.h>
24 #include <linux/aio.h>
25 #include <linux/uio.h>
26 #include <linux/refcount.h>
27 #include <linux/delay.h>
28 #include <linux/device.h>
29 #include <linux/moduleparam.h>
30 
31 #include <linux/usb/gadgetfs.h>
32 #include <linux/usb/gadget.h>
33 
34 
35 /*
36  * The gadgetfs API maps each endpoint to a file descriptor so that you
37  * can use standard synchronous read/write calls for I/O.  There's some
38  * O_NONBLOCK and O_ASYNC/FASYNC style i/o support.  Example usermode
39  * drivers show how this works in practice.  You can also use AIO to
40  * eliminate I/O gaps between requests, to help when streaming data.
41  *
42  * Key parts that must be USB-specific are protocols defining how the
43  * read/write operations relate to the hardware state machines.  There
44  * are two types of files.  One type is for the device, implementing ep0.
45  * The other type is for each IN or OUT endpoint.  In both cases, the
46  * user mode driver must configure the hardware before using it.
47  *
48  * - First, dev_config() is called when /dev/gadget/$CHIP is configured
49  *   (by writing configuration and device descriptors).  Afterwards it
50  *   may serve as a source of device events, used to handle all control
51  *   requests other than basic enumeration.
52  *
53  * - Then, after a SET_CONFIGURATION control request, ep_config() is
54  *   called when each /dev/gadget/ep* file is configured (by writing
55  *   endpoint descriptors).  Afterwards these files are used to write()
56  *   IN data or to read() OUT data.  To halt the endpoint, a "wrong
57  *   direction" request is issued (like reading an IN endpoint).
58  *
59  * Unlike "usbfs" the only ioctl()s are for things that are rare, and maybe
60  * not possible on all hardware.  For example, precise fault handling with
61  * respect to data left in endpoint fifos after aborted operations; or
62  * selective clearing of endpoint halts, to implement SET_INTERFACE.
63  */
64 
65 #define	DRIVER_DESC	"USB Gadget filesystem"
66 #define	DRIVER_VERSION	"24 Aug 2004"
67 
68 static const char driver_desc [] = DRIVER_DESC;
69 static const char shortname [] = "gadgetfs";
70 
71 MODULE_DESCRIPTION (DRIVER_DESC);
72 MODULE_AUTHOR ("David Brownell");
73 MODULE_LICENSE ("GPL");
74 
75 static int ep_open(struct inode *, struct file *);
76 
77 
78 /*----------------------------------------------------------------------*/
79 
80 #define GADGETFS_MAGIC		0xaee71ee7
81 
82 /* /dev/gadget/$CHIP represents ep0 and the whole device */
83 enum ep0_state {
84 	/* DISABLED is the initial state. */
85 	STATE_DEV_DISABLED = 0,
86 
87 	/* Only one open() of /dev/gadget/$CHIP; only one file tracks
88 	 * ep0/device i/o modes and binding to the controller.  Driver
89 	 * must always write descriptors to initialize the device, then
90 	 * the device becomes UNCONNECTED until enumeration.
91 	 */
92 	STATE_DEV_OPENED,
93 
94 	/* From then on, ep0 fd is in either of two basic modes:
95 	 * - (UN)CONNECTED: read usb_gadgetfs_event(s) from it
96 	 * - SETUP: read/write will transfer control data and succeed;
97 	 *   or if "wrong direction", performs protocol stall
98 	 */
99 	STATE_DEV_UNCONNECTED,
100 	STATE_DEV_CONNECTED,
101 	STATE_DEV_SETUP,
102 
103 	/* UNBOUND means the driver closed ep0, so the device won't be
104 	 * accessible again (DEV_DISABLED) until all fds are closed.
105 	 */
106 	STATE_DEV_UNBOUND,
107 };
108 
109 /* enough for the whole queue: most events invalidate others */
110 #define	N_EVENT			5
111 
112 struct dev_data {
113 	spinlock_t			lock;
114 	refcount_t			count;
115 	int				udc_usage;
116 	enum ep0_state			state;		/* P: lock */
117 	struct usb_gadgetfs_event	event [N_EVENT];
118 	unsigned			ev_next;
119 	struct fasync_struct		*fasync;
120 	u8				current_config;
121 
122 	/* drivers reading ep0 MUST handle control requests (SETUP)
123 	 * reported that way; else the host will time out.
124 	 */
125 	unsigned			usermode_setup : 1,
126 					setup_in : 1,
127 					setup_can_stall : 1,
128 					setup_out_ready : 1,
129 					setup_out_error : 1,
130 					setup_abort : 1,
131 					gadget_registered : 1;
132 	unsigned			setup_wLength;
133 
134 	/* the rest is basically write-once */
135 	struct usb_config_descriptor	*config, *hs_config;
136 	struct usb_device_descriptor	*dev;
137 	struct usb_request		*req;
138 	struct usb_gadget		*gadget;
139 	struct list_head		epfiles;
140 	void				*buf;
141 	wait_queue_head_t		wait;
142 	struct super_block		*sb;
143 	struct dentry			*dentry;
144 
145 	/* except this scratch i/o buffer for ep0 */
146 	u8				rbuf [256];
147 };
148 
149 static inline void get_dev (struct dev_data *data)
150 {
151 	refcount_inc (&data->count);
152 }
153 
154 static void put_dev (struct dev_data *data)
155 {
156 	if (likely (!refcount_dec_and_test (&data->count)))
157 		return;
158 	/* needs no more cleanup */
159 	BUG_ON (waitqueue_active (&data->wait));
160 	kfree (data);
161 }
162 
163 static struct dev_data *dev_new (void)
164 {
165 	struct dev_data		*dev;
166 
167 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
168 	if (!dev)
169 		return NULL;
170 	dev->state = STATE_DEV_DISABLED;
171 	refcount_set (&dev->count, 1);
172 	spin_lock_init (&dev->lock);
173 	INIT_LIST_HEAD (&dev->epfiles);
174 	init_waitqueue_head (&dev->wait);
175 	return dev;
176 }
177 
178 /*----------------------------------------------------------------------*/
179 
180 /* other /dev/gadget/$ENDPOINT files represent endpoints */
181 enum ep_state {
182 	STATE_EP_DISABLED = 0,
183 	STATE_EP_READY,
184 	STATE_EP_ENABLED,
185 	STATE_EP_UNBOUND,
186 };
187 
188 struct ep_data {
189 	struct mutex			lock;
190 	enum ep_state			state;
191 	refcount_t			count;
192 	struct dev_data			*dev;
193 	/* must hold dev->lock before accessing ep or req */
194 	struct usb_ep			*ep;
195 	struct usb_request		*req;
196 	ssize_t				status;
197 	char				name [16];
198 	struct usb_endpoint_descriptor	desc, hs_desc;
199 	struct list_head		epfiles;
200 	wait_queue_head_t		wait;
201 	struct dentry			*dentry;
202 };
203 
204 static inline void get_ep (struct ep_data *data)
205 {
206 	refcount_inc (&data->count);
207 }
208 
209 static void put_ep (struct ep_data *data)
210 {
211 	if (likely (!refcount_dec_and_test (&data->count)))
212 		return;
213 	put_dev (data->dev);
214 	/* needs no more cleanup */
215 	BUG_ON (!list_empty (&data->epfiles));
216 	BUG_ON (waitqueue_active (&data->wait));
217 	kfree (data);
218 }
219 
220 /*----------------------------------------------------------------------*/
221 
222 /* most "how to use the hardware" policy choices are in userspace:
223  * mapping endpoint roles (which the driver needs) to the capabilities
224  * which the usb controller has.  most of those capabilities are exposed
225  * implicitly, starting with the driver name and then endpoint names.
226  */
227 
228 static const char *CHIP;
229 
230 /*----------------------------------------------------------------------*/
231 
232 /* NOTE:  don't use dev_printk calls before binding to the gadget
233  * at the end of ep0 configuration, or after unbind.
234  */
235 
236 /* too wordy: dev_printk(level , &(d)->gadget->dev , fmt , ## args) */
237 #define xprintk(d,level,fmt,args...) \
238 	printk(level "%s: " fmt , shortname , ## args)
239 
240 #ifdef DEBUG
241 #define DBG(dev,fmt,args...) \
242 	xprintk(dev , KERN_DEBUG , fmt , ## args)
243 #else
244 #define DBG(dev,fmt,args...) \
245 	do { } while (0)
246 #endif /* DEBUG */
247 
248 #ifdef VERBOSE_DEBUG
249 #define VDEBUG	DBG
250 #else
251 #define VDEBUG(dev,fmt,args...) \
252 	do { } while (0)
253 #endif /* DEBUG */
254 
255 #define ERROR(dev,fmt,args...) \
256 	xprintk(dev , KERN_ERR , fmt , ## args)
257 #define INFO(dev,fmt,args...) \
258 	xprintk(dev , KERN_INFO , fmt , ## args)
259 
260 
261 /*----------------------------------------------------------------------*/
262 
263 /* SYNCHRONOUS ENDPOINT OPERATIONS (bulk/intr/iso)
264  *
265  * After opening, configure non-control endpoints.  Then use normal
266  * stream read() and write() requests; and maybe ioctl() to get more
267  * precise FIFO status when recovering from cancellation.
268  */
269 
270 static void epio_complete (struct usb_ep *ep, struct usb_request *req)
271 {
272 	struct ep_data	*epdata = ep->driver_data;
273 
274 	if (!req->context)
275 		return;
276 	if (req->status)
277 		epdata->status = req->status;
278 	else
279 		epdata->status = req->actual;
280 	complete ((struct completion *)req->context);
281 }
282 
283 /* tasklock endpoint, returning when it's connected.
284  * still need dev->lock to use epdata->ep.
285  */
286 static int
287 get_ready_ep (unsigned f_flags, struct ep_data *epdata, bool is_write)
288 {
289 	int	val;
290 
291 	if (f_flags & O_NONBLOCK) {
292 		if (!mutex_trylock(&epdata->lock))
293 			goto nonblock;
294 		if (epdata->state != STATE_EP_ENABLED &&
295 		    (!is_write || epdata->state != STATE_EP_READY)) {
296 			mutex_unlock(&epdata->lock);
297 nonblock:
298 			val = -EAGAIN;
299 		} else
300 			val = 0;
301 		return val;
302 	}
303 
304 	val = mutex_lock_interruptible(&epdata->lock);
305 	if (val < 0)
306 		return val;
307 
308 	switch (epdata->state) {
309 	case STATE_EP_ENABLED:
310 		return 0;
311 	case STATE_EP_READY:			/* not configured yet */
312 		if (is_write)
313 			return 0;
314 		// FALLTHRU
315 	case STATE_EP_UNBOUND:			/* clean disconnect */
316 		break;
317 	// case STATE_EP_DISABLED:		/* "can't happen" */
318 	default:				/* error! */
319 		pr_debug ("%s: ep %p not available, state %d\n",
320 				shortname, epdata, epdata->state);
321 	}
322 	mutex_unlock(&epdata->lock);
323 	return -ENODEV;
324 }
325 
326 static ssize_t
327 ep_io (struct ep_data *epdata, void *buf, unsigned len)
328 {
329 	DECLARE_COMPLETION_ONSTACK (done);
330 	int value;
331 
332 	spin_lock_irq (&epdata->dev->lock);
333 	if (likely (epdata->ep != NULL)) {
334 		struct usb_request	*req = epdata->req;
335 
336 		req->context = &done;
337 		req->complete = epio_complete;
338 		req->buf = buf;
339 		req->length = len;
340 		value = usb_ep_queue (epdata->ep, req, GFP_ATOMIC);
341 	} else
342 		value = -ENODEV;
343 	spin_unlock_irq (&epdata->dev->lock);
344 
345 	if (likely (value == 0)) {
346 		value = wait_event_interruptible (done.wait, done.done);
347 		if (value != 0) {
348 			spin_lock_irq (&epdata->dev->lock);
349 			if (likely (epdata->ep != NULL)) {
350 				DBG (epdata->dev, "%s i/o interrupted\n",
351 						epdata->name);
352 				usb_ep_dequeue (epdata->ep, epdata->req);
353 				spin_unlock_irq (&epdata->dev->lock);
354 
355 				wait_event (done.wait, done.done);
356 				if (epdata->status == -ECONNRESET)
357 					epdata->status = -EINTR;
358 			} else {
359 				spin_unlock_irq (&epdata->dev->lock);
360 
361 				DBG (epdata->dev, "endpoint gone\n");
362 				epdata->status = -ENODEV;
363 			}
364 		}
365 		return epdata->status;
366 	}
367 	return value;
368 }
369 
370 static int
371 ep_release (struct inode *inode, struct file *fd)
372 {
373 	struct ep_data		*data = fd->private_data;
374 	int value;
375 
376 	value = mutex_lock_interruptible(&data->lock);
377 	if (value < 0)
378 		return value;
379 
380 	/* clean up if this can be reopened */
381 	if (data->state != STATE_EP_UNBOUND) {
382 		data->state = STATE_EP_DISABLED;
383 		data->desc.bDescriptorType = 0;
384 		data->hs_desc.bDescriptorType = 0;
385 		usb_ep_disable(data->ep);
386 	}
387 	mutex_unlock(&data->lock);
388 	put_ep (data);
389 	return 0;
390 }
391 
392 static long ep_ioctl(struct file *fd, unsigned code, unsigned long value)
393 {
394 	struct ep_data		*data = fd->private_data;
395 	int			status;
396 
397 	if ((status = get_ready_ep (fd->f_flags, data, false)) < 0)
398 		return status;
399 
400 	spin_lock_irq (&data->dev->lock);
401 	if (likely (data->ep != NULL)) {
402 		switch (code) {
403 		case GADGETFS_FIFO_STATUS:
404 			status = usb_ep_fifo_status (data->ep);
405 			break;
406 		case GADGETFS_FIFO_FLUSH:
407 			usb_ep_fifo_flush (data->ep);
408 			break;
409 		case GADGETFS_CLEAR_HALT:
410 			status = usb_ep_clear_halt (data->ep);
411 			break;
412 		default:
413 			status = -ENOTTY;
414 		}
415 	} else
416 		status = -ENODEV;
417 	spin_unlock_irq (&data->dev->lock);
418 	mutex_unlock(&data->lock);
419 	return status;
420 }
421 
422 /*----------------------------------------------------------------------*/
423 
424 /* ASYNCHRONOUS ENDPOINT I/O OPERATIONS (bulk/intr/iso) */
425 
426 struct kiocb_priv {
427 	struct usb_request	*req;
428 	struct ep_data		*epdata;
429 	struct kiocb		*iocb;
430 	struct mm_struct	*mm;
431 	struct work_struct	work;
432 	void			*buf;
433 	struct iov_iter		to;
434 	const void		*to_free;
435 	unsigned		actual;
436 };
437 
438 static int ep_aio_cancel(struct kiocb *iocb)
439 {
440 	struct kiocb_priv	*priv = iocb->private;
441 	struct ep_data		*epdata;
442 	int			value;
443 
444 	local_irq_disable();
445 	epdata = priv->epdata;
446 	// spin_lock(&epdata->dev->lock);
447 	if (likely(epdata && epdata->ep && priv->req))
448 		value = usb_ep_dequeue (epdata->ep, priv->req);
449 	else
450 		value = -EINVAL;
451 	// spin_unlock(&epdata->dev->lock);
452 	local_irq_enable();
453 
454 	return value;
455 }
456 
457 static void ep_user_copy_worker(struct work_struct *work)
458 {
459 	struct kiocb_priv *priv = container_of(work, struct kiocb_priv, work);
460 	struct mm_struct *mm = priv->mm;
461 	struct kiocb *iocb = priv->iocb;
462 	size_t ret;
463 
464 	use_mm(mm);
465 	ret = copy_to_iter(priv->buf, priv->actual, &priv->to);
466 	unuse_mm(mm);
467 	if (!ret)
468 		ret = -EFAULT;
469 
470 	/* completing the iocb can drop the ctx and mm, don't touch mm after */
471 	iocb->ki_complete(iocb, ret, ret);
472 
473 	kfree(priv->buf);
474 	kfree(priv->to_free);
475 	kfree(priv);
476 }
477 
478 static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
479 {
480 	struct kiocb		*iocb = req->context;
481 	struct kiocb_priv	*priv = iocb->private;
482 	struct ep_data		*epdata = priv->epdata;
483 
484 	/* lock against disconnect (and ideally, cancel) */
485 	spin_lock(&epdata->dev->lock);
486 	priv->req = NULL;
487 	priv->epdata = NULL;
488 
489 	/* if this was a write or a read returning no data then we
490 	 * don't need to copy anything to userspace, so we can
491 	 * complete the aio request immediately.
492 	 */
493 	if (priv->to_free == NULL || unlikely(req->actual == 0)) {
494 		kfree(req->buf);
495 		kfree(priv->to_free);
496 		kfree(priv);
497 		iocb->private = NULL;
498 		/* aio_complete() reports bytes-transferred _and_ faults */
499 
500 		iocb->ki_complete(iocb, req->actual ? req->actual : req->status,
501 				req->status);
502 	} else {
503 		/* ep_copy_to_user() won't report both; we hide some faults */
504 		if (unlikely(0 != req->status))
505 			DBG(epdata->dev, "%s fault %d len %d\n",
506 				ep->name, req->status, req->actual);
507 
508 		priv->buf = req->buf;
509 		priv->actual = req->actual;
510 		INIT_WORK(&priv->work, ep_user_copy_worker);
511 		schedule_work(&priv->work);
512 	}
513 
514 	usb_ep_free_request(ep, req);
515 	spin_unlock(&epdata->dev->lock);
516 	put_ep(epdata);
517 }
518 
519 static ssize_t ep_aio(struct kiocb *iocb,
520 		      struct kiocb_priv *priv,
521 		      struct ep_data *epdata,
522 		      char *buf,
523 		      size_t len)
524 {
525 	struct usb_request *req;
526 	ssize_t value;
527 
528 	iocb->private = priv;
529 	priv->iocb = iocb;
530 
531 	kiocb_set_cancel_fn(iocb, ep_aio_cancel);
532 	get_ep(epdata);
533 	priv->epdata = epdata;
534 	priv->actual = 0;
535 	priv->mm = current->mm; /* mm teardown waits for iocbs in exit_aio() */
536 
537 	/* each kiocb is coupled to one usb_request, but we can't
538 	 * allocate or submit those if the host disconnected.
539 	 */
540 	spin_lock_irq(&epdata->dev->lock);
541 	value = -ENODEV;
542 	if (unlikely(epdata->ep == NULL))
543 		goto fail;
544 
545 	req = usb_ep_alloc_request(epdata->ep, GFP_ATOMIC);
546 	value = -ENOMEM;
547 	if (unlikely(!req))
548 		goto fail;
549 
550 	priv->req = req;
551 	req->buf = buf;
552 	req->length = len;
553 	req->complete = ep_aio_complete;
554 	req->context = iocb;
555 	value = usb_ep_queue(epdata->ep, req, GFP_ATOMIC);
556 	if (unlikely(0 != value)) {
557 		usb_ep_free_request(epdata->ep, req);
558 		goto fail;
559 	}
560 	spin_unlock_irq(&epdata->dev->lock);
561 	return -EIOCBQUEUED;
562 
563 fail:
564 	spin_unlock_irq(&epdata->dev->lock);
565 	kfree(priv->to_free);
566 	kfree(priv);
567 	put_ep(epdata);
568 	return value;
569 }
570 
571 static ssize_t
572 ep_read_iter(struct kiocb *iocb, struct iov_iter *to)
573 {
574 	struct file *file = iocb->ki_filp;
575 	struct ep_data *epdata = file->private_data;
576 	size_t len = iov_iter_count(to);
577 	ssize_t value;
578 	char *buf;
579 
580 	if ((value = get_ready_ep(file->f_flags, epdata, false)) < 0)
581 		return value;
582 
583 	/* halt any endpoint by doing a "wrong direction" i/o call */
584 	if (usb_endpoint_dir_in(&epdata->desc)) {
585 		if (usb_endpoint_xfer_isoc(&epdata->desc) ||
586 		    !is_sync_kiocb(iocb)) {
587 			mutex_unlock(&epdata->lock);
588 			return -EINVAL;
589 		}
590 		DBG (epdata->dev, "%s halt\n", epdata->name);
591 		spin_lock_irq(&epdata->dev->lock);
592 		if (likely(epdata->ep != NULL))
593 			usb_ep_set_halt(epdata->ep);
594 		spin_unlock_irq(&epdata->dev->lock);
595 		mutex_unlock(&epdata->lock);
596 		return -EBADMSG;
597 	}
598 
599 	buf = kmalloc(len, GFP_KERNEL);
600 	if (unlikely(!buf)) {
601 		mutex_unlock(&epdata->lock);
602 		return -ENOMEM;
603 	}
604 	if (is_sync_kiocb(iocb)) {
605 		value = ep_io(epdata, buf, len);
606 		if (value >= 0 && (copy_to_iter(buf, value, to) != value))
607 			value = -EFAULT;
608 	} else {
609 		struct kiocb_priv *priv = kzalloc(sizeof *priv, GFP_KERNEL);
610 		value = -ENOMEM;
611 		if (!priv)
612 			goto fail;
613 		priv->to_free = dup_iter(&priv->to, to, GFP_KERNEL);
614 		if (!priv->to_free) {
615 			kfree(priv);
616 			goto fail;
617 		}
618 		value = ep_aio(iocb, priv, epdata, buf, len);
619 		if (value == -EIOCBQUEUED)
620 			buf = NULL;
621 	}
622 fail:
623 	kfree(buf);
624 	mutex_unlock(&epdata->lock);
625 	return value;
626 }
627 
628 static ssize_t ep_config(struct ep_data *, const char *, size_t);
629 
630 static ssize_t
631 ep_write_iter(struct kiocb *iocb, struct iov_iter *from)
632 {
633 	struct file *file = iocb->ki_filp;
634 	struct ep_data *epdata = file->private_data;
635 	size_t len = iov_iter_count(from);
636 	bool configured;
637 	ssize_t value;
638 	char *buf;
639 
640 	if ((value = get_ready_ep(file->f_flags, epdata, true)) < 0)
641 		return value;
642 
643 	configured = epdata->state == STATE_EP_ENABLED;
644 
645 	/* halt any endpoint by doing a "wrong direction" i/o call */
646 	if (configured && !usb_endpoint_dir_in(&epdata->desc)) {
647 		if (usb_endpoint_xfer_isoc(&epdata->desc) ||
648 		    !is_sync_kiocb(iocb)) {
649 			mutex_unlock(&epdata->lock);
650 			return -EINVAL;
651 		}
652 		DBG (epdata->dev, "%s halt\n", epdata->name);
653 		spin_lock_irq(&epdata->dev->lock);
654 		if (likely(epdata->ep != NULL))
655 			usb_ep_set_halt(epdata->ep);
656 		spin_unlock_irq(&epdata->dev->lock);
657 		mutex_unlock(&epdata->lock);
658 		return -EBADMSG;
659 	}
660 
661 	buf = kmalloc(len, GFP_KERNEL);
662 	if (unlikely(!buf)) {
663 		mutex_unlock(&epdata->lock);
664 		return -ENOMEM;
665 	}
666 
667 	if (unlikely(!copy_from_iter_full(buf, len, from))) {
668 		value = -EFAULT;
669 		goto out;
670 	}
671 
672 	if (unlikely(!configured)) {
673 		value = ep_config(epdata, buf, len);
674 	} else if (is_sync_kiocb(iocb)) {
675 		value = ep_io(epdata, buf, len);
676 	} else {
677 		struct kiocb_priv *priv = kzalloc(sizeof *priv, GFP_KERNEL);
678 		value = -ENOMEM;
679 		if (priv) {
680 			value = ep_aio(iocb, priv, epdata, buf, len);
681 			if (value == -EIOCBQUEUED)
682 				buf = NULL;
683 		}
684 	}
685 out:
686 	kfree(buf);
687 	mutex_unlock(&epdata->lock);
688 	return value;
689 }
690 
691 /*----------------------------------------------------------------------*/
692 
693 /* used after endpoint configuration */
694 static const struct file_operations ep_io_operations = {
695 	.owner =	THIS_MODULE,
696 
697 	.open =		ep_open,
698 	.release =	ep_release,
699 	.llseek =	no_llseek,
700 	.unlocked_ioctl = ep_ioctl,
701 	.read_iter =	ep_read_iter,
702 	.write_iter =	ep_write_iter,
703 };
704 
705 /* ENDPOINT INITIALIZATION
706  *
707  *     fd = open ("/dev/gadget/$ENDPOINT", O_RDWR)
708  *     status = write (fd, descriptors, sizeof descriptors)
709  *
710  * That write establishes the endpoint configuration, configuring
711  * the controller to process bulk, interrupt, or isochronous transfers
712  * at the right maxpacket size, and so on.
713  *
714  * The descriptors are message type 1, identified by a host order u32
715  * at the beginning of what's written.  Descriptor order is: full/low
716  * speed descriptor, then optional high speed descriptor.
717  */
718 static ssize_t
719 ep_config (struct ep_data *data, const char *buf, size_t len)
720 {
721 	struct usb_ep		*ep;
722 	u32			tag;
723 	int			value, length = len;
724 
725 	if (data->state != STATE_EP_READY) {
726 		value = -EL2HLT;
727 		goto fail;
728 	}
729 
730 	value = len;
731 	if (len < USB_DT_ENDPOINT_SIZE + 4)
732 		goto fail0;
733 
734 	/* we might need to change message format someday */
735 	memcpy(&tag, buf, 4);
736 	if (tag != 1) {
737 		DBG(data->dev, "config %s, bad tag %d\n", data->name, tag);
738 		goto fail0;
739 	}
740 	buf += 4;
741 	len -= 4;
742 
743 	/* NOTE:  audio endpoint extensions not accepted here;
744 	 * just don't include the extra bytes.
745 	 */
746 
747 	/* full/low speed descriptor, then high speed */
748 	memcpy(&data->desc, buf, USB_DT_ENDPOINT_SIZE);
749 	if (data->desc.bLength != USB_DT_ENDPOINT_SIZE
750 			|| data->desc.bDescriptorType != USB_DT_ENDPOINT)
751 		goto fail0;
752 	if (len != USB_DT_ENDPOINT_SIZE) {
753 		if (len != 2 * USB_DT_ENDPOINT_SIZE)
754 			goto fail0;
755 		memcpy(&data->hs_desc, buf + USB_DT_ENDPOINT_SIZE,
756 			USB_DT_ENDPOINT_SIZE);
757 		if (data->hs_desc.bLength != USB_DT_ENDPOINT_SIZE
758 				|| data->hs_desc.bDescriptorType
759 					!= USB_DT_ENDPOINT) {
760 			DBG(data->dev, "config %s, bad hs length or type\n",
761 					data->name);
762 			goto fail0;
763 		}
764 	}
765 
766 	spin_lock_irq (&data->dev->lock);
767 	if (data->dev->state == STATE_DEV_UNBOUND) {
768 		value = -ENOENT;
769 		goto gone;
770 	} else {
771 		ep = data->ep;
772 		if (ep == NULL) {
773 			value = -ENODEV;
774 			goto gone;
775 		}
776 	}
777 	switch (data->dev->gadget->speed) {
778 	case USB_SPEED_LOW:
779 	case USB_SPEED_FULL:
780 		ep->desc = &data->desc;
781 		break;
782 	case USB_SPEED_HIGH:
783 		/* fails if caller didn't provide that descriptor... */
784 		ep->desc = &data->hs_desc;
785 		break;
786 	default:
787 		DBG(data->dev, "unconnected, %s init abandoned\n",
788 				data->name);
789 		value = -EINVAL;
790 		goto gone;
791 	}
792 	value = usb_ep_enable(ep);
793 	if (value == 0) {
794 		data->state = STATE_EP_ENABLED;
795 		value = length;
796 	}
797 gone:
798 	spin_unlock_irq (&data->dev->lock);
799 	if (value < 0) {
800 fail:
801 		data->desc.bDescriptorType = 0;
802 		data->hs_desc.bDescriptorType = 0;
803 	}
804 	return value;
805 fail0:
806 	value = -EINVAL;
807 	goto fail;
808 }
809 
810 static int
811 ep_open (struct inode *inode, struct file *fd)
812 {
813 	struct ep_data		*data = inode->i_private;
814 	int			value = -EBUSY;
815 
816 	if (mutex_lock_interruptible(&data->lock) != 0)
817 		return -EINTR;
818 	spin_lock_irq (&data->dev->lock);
819 	if (data->dev->state == STATE_DEV_UNBOUND)
820 		value = -ENOENT;
821 	else if (data->state == STATE_EP_DISABLED) {
822 		value = 0;
823 		data->state = STATE_EP_READY;
824 		get_ep (data);
825 		fd->private_data = data;
826 		VDEBUG (data->dev, "%s ready\n", data->name);
827 	} else
828 		DBG (data->dev, "%s state %d\n",
829 			data->name, data->state);
830 	spin_unlock_irq (&data->dev->lock);
831 	mutex_unlock(&data->lock);
832 	return value;
833 }
834 
835 /*----------------------------------------------------------------------*/
836 
837 /* EP0 IMPLEMENTATION can be partly in userspace.
838  *
839  * Drivers that use this facility receive various events, including
840  * control requests the kernel doesn't handle.  Drivers that don't
841  * use this facility may be too simple-minded for real applications.
842  */
843 
844 static inline void ep0_readable (struct dev_data *dev)
845 {
846 	wake_up (&dev->wait);
847 	kill_fasync (&dev->fasync, SIGIO, POLL_IN);
848 }
849 
850 static void clean_req (struct usb_ep *ep, struct usb_request *req)
851 {
852 	struct dev_data		*dev = ep->driver_data;
853 
854 	if (req->buf != dev->rbuf) {
855 		kfree(req->buf);
856 		req->buf = dev->rbuf;
857 	}
858 	req->complete = epio_complete;
859 	dev->setup_out_ready = 0;
860 }
861 
862 static void ep0_complete (struct usb_ep *ep, struct usb_request *req)
863 {
864 	struct dev_data		*dev = ep->driver_data;
865 	unsigned long		flags;
866 	int			free = 1;
867 
868 	/* for control OUT, data must still get to userspace */
869 	spin_lock_irqsave(&dev->lock, flags);
870 	if (!dev->setup_in) {
871 		dev->setup_out_error = (req->status != 0);
872 		if (!dev->setup_out_error)
873 			free = 0;
874 		dev->setup_out_ready = 1;
875 		ep0_readable (dev);
876 	}
877 
878 	/* clean up as appropriate */
879 	if (free && req->buf != &dev->rbuf)
880 		clean_req (ep, req);
881 	req->complete = epio_complete;
882 	spin_unlock_irqrestore(&dev->lock, flags);
883 }
884 
885 static int setup_req (struct usb_ep *ep, struct usb_request *req, u16 len)
886 {
887 	struct dev_data	*dev = ep->driver_data;
888 
889 	if (dev->setup_out_ready) {
890 		DBG (dev, "ep0 request busy!\n");
891 		return -EBUSY;
892 	}
893 	if (len > sizeof (dev->rbuf))
894 		req->buf = kmalloc(len, GFP_ATOMIC);
895 	if (req->buf == NULL) {
896 		req->buf = dev->rbuf;
897 		return -ENOMEM;
898 	}
899 	req->complete = ep0_complete;
900 	req->length = len;
901 	req->zero = 0;
902 	return 0;
903 }
904 
905 static ssize_t
906 ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
907 {
908 	struct dev_data			*dev = fd->private_data;
909 	ssize_t				retval;
910 	enum ep0_state			state;
911 
912 	spin_lock_irq (&dev->lock);
913 	if (dev->state <= STATE_DEV_OPENED) {
914 		retval = -EINVAL;
915 		goto done;
916 	}
917 
918 	/* report fd mode change before acting on it */
919 	if (dev->setup_abort) {
920 		dev->setup_abort = 0;
921 		retval = -EIDRM;
922 		goto done;
923 	}
924 
925 	/* control DATA stage */
926 	if ((state = dev->state) == STATE_DEV_SETUP) {
927 
928 		if (dev->setup_in) {		/* stall IN */
929 			VDEBUG(dev, "ep0in stall\n");
930 			(void) usb_ep_set_halt (dev->gadget->ep0);
931 			retval = -EL2HLT;
932 			dev->state = STATE_DEV_CONNECTED;
933 
934 		} else if (len == 0) {		/* ack SET_CONFIGURATION etc */
935 			struct usb_ep		*ep = dev->gadget->ep0;
936 			struct usb_request	*req = dev->req;
937 
938 			if ((retval = setup_req (ep, req, 0)) == 0) {
939 				++dev->udc_usage;
940 				spin_unlock_irq (&dev->lock);
941 				retval = usb_ep_queue (ep, req, GFP_KERNEL);
942 				spin_lock_irq (&dev->lock);
943 				--dev->udc_usage;
944 			}
945 			dev->state = STATE_DEV_CONNECTED;
946 
947 			/* assume that was SET_CONFIGURATION */
948 			if (dev->current_config) {
949 				unsigned power;
950 
951 				if (gadget_is_dualspeed(dev->gadget)
952 						&& (dev->gadget->speed
953 							== USB_SPEED_HIGH))
954 					power = dev->hs_config->bMaxPower;
955 				else
956 					power = dev->config->bMaxPower;
957 				usb_gadget_vbus_draw(dev->gadget, 2 * power);
958 			}
959 
960 		} else {			/* collect OUT data */
961 			if ((fd->f_flags & O_NONBLOCK) != 0
962 					&& !dev->setup_out_ready) {
963 				retval = -EAGAIN;
964 				goto done;
965 			}
966 			spin_unlock_irq (&dev->lock);
967 			retval = wait_event_interruptible (dev->wait,
968 					dev->setup_out_ready != 0);
969 
970 			/* FIXME state could change from under us */
971 			spin_lock_irq (&dev->lock);
972 			if (retval)
973 				goto done;
974 
975 			if (dev->state != STATE_DEV_SETUP) {
976 				retval = -ECANCELED;
977 				goto done;
978 			}
979 			dev->state = STATE_DEV_CONNECTED;
980 
981 			if (dev->setup_out_error)
982 				retval = -EIO;
983 			else {
984 				len = min (len, (size_t)dev->req->actual);
985 				++dev->udc_usage;
986 				spin_unlock_irq(&dev->lock);
987 				if (copy_to_user (buf, dev->req->buf, len))
988 					retval = -EFAULT;
989 				else
990 					retval = len;
991 				spin_lock_irq(&dev->lock);
992 				--dev->udc_usage;
993 				clean_req (dev->gadget->ep0, dev->req);
994 				/* NOTE userspace can't yet choose to stall */
995 			}
996 		}
997 		goto done;
998 	}
999 
1000 	/* else normal: return event data */
1001 	if (len < sizeof dev->event [0]) {
1002 		retval = -EINVAL;
1003 		goto done;
1004 	}
1005 	len -= len % sizeof (struct usb_gadgetfs_event);
1006 	dev->usermode_setup = 1;
1007 
1008 scan:
1009 	/* return queued events right away */
1010 	if (dev->ev_next != 0) {
1011 		unsigned		i, n;
1012 
1013 		n = len / sizeof (struct usb_gadgetfs_event);
1014 		if (dev->ev_next < n)
1015 			n = dev->ev_next;
1016 
1017 		/* ep0 i/o has special semantics during STATE_DEV_SETUP */
1018 		for (i = 0; i < n; i++) {
1019 			if (dev->event [i].type == GADGETFS_SETUP) {
1020 				dev->state = STATE_DEV_SETUP;
1021 				n = i + 1;
1022 				break;
1023 			}
1024 		}
1025 		spin_unlock_irq (&dev->lock);
1026 		len = n * sizeof (struct usb_gadgetfs_event);
1027 		if (copy_to_user (buf, &dev->event, len))
1028 			retval = -EFAULT;
1029 		else
1030 			retval = len;
1031 		if (len > 0) {
1032 			/* NOTE this doesn't guard against broken drivers;
1033 			 * concurrent ep0 readers may lose events.
1034 			 */
1035 			spin_lock_irq (&dev->lock);
1036 			if (dev->ev_next > n) {
1037 				memmove(&dev->event[0], &dev->event[n],
1038 					sizeof (struct usb_gadgetfs_event)
1039 						* (dev->ev_next - n));
1040 			}
1041 			dev->ev_next -= n;
1042 			spin_unlock_irq (&dev->lock);
1043 		}
1044 		return retval;
1045 	}
1046 	if (fd->f_flags & O_NONBLOCK) {
1047 		retval = -EAGAIN;
1048 		goto done;
1049 	}
1050 
1051 	switch (state) {
1052 	default:
1053 		DBG (dev, "fail %s, state %d\n", __func__, state);
1054 		retval = -ESRCH;
1055 		break;
1056 	case STATE_DEV_UNCONNECTED:
1057 	case STATE_DEV_CONNECTED:
1058 		spin_unlock_irq (&dev->lock);
1059 		DBG (dev, "%s wait\n", __func__);
1060 
1061 		/* wait for events */
1062 		retval = wait_event_interruptible (dev->wait,
1063 				dev->ev_next != 0);
1064 		if (retval < 0)
1065 			return retval;
1066 		spin_lock_irq (&dev->lock);
1067 		goto scan;
1068 	}
1069 
1070 done:
1071 	spin_unlock_irq (&dev->lock);
1072 	return retval;
1073 }
1074 
1075 static struct usb_gadgetfs_event *
1076 next_event (struct dev_data *dev, enum usb_gadgetfs_event_type type)
1077 {
1078 	struct usb_gadgetfs_event	*event;
1079 	unsigned			i;
1080 
1081 	switch (type) {
1082 	/* these events purge the queue */
1083 	case GADGETFS_DISCONNECT:
1084 		if (dev->state == STATE_DEV_SETUP)
1085 			dev->setup_abort = 1;
1086 		// FALL THROUGH
1087 	case GADGETFS_CONNECT:
1088 		dev->ev_next = 0;
1089 		break;
1090 	case GADGETFS_SETUP:		/* previous request timed out */
1091 	case GADGETFS_SUSPEND:		/* same effect */
1092 		/* these events can't be repeated */
1093 		for (i = 0; i != dev->ev_next; i++) {
1094 			if (dev->event [i].type != type)
1095 				continue;
1096 			DBG(dev, "discard old event[%d] %d\n", i, type);
1097 			dev->ev_next--;
1098 			if (i == dev->ev_next)
1099 				break;
1100 			/* indices start at zero, for simplicity */
1101 			memmove (&dev->event [i], &dev->event [i + 1],
1102 				sizeof (struct usb_gadgetfs_event)
1103 					* (dev->ev_next - i));
1104 		}
1105 		break;
1106 	default:
1107 		BUG ();
1108 	}
1109 	VDEBUG(dev, "event[%d] = %d\n", dev->ev_next, type);
1110 	event = &dev->event [dev->ev_next++];
1111 	BUG_ON (dev->ev_next > N_EVENT);
1112 	memset (event, 0, sizeof *event);
1113 	event->type = type;
1114 	return event;
1115 }
1116 
1117 static ssize_t
1118 ep0_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
1119 {
1120 	struct dev_data		*dev = fd->private_data;
1121 	ssize_t			retval = -ESRCH;
1122 
1123 	/* report fd mode change before acting on it */
1124 	if (dev->setup_abort) {
1125 		dev->setup_abort = 0;
1126 		retval = -EIDRM;
1127 
1128 	/* data and/or status stage for control request */
1129 	} else if (dev->state == STATE_DEV_SETUP) {
1130 
1131 		len = min_t(size_t, len, dev->setup_wLength);
1132 		if (dev->setup_in) {
1133 			retval = setup_req (dev->gadget->ep0, dev->req, len);
1134 			if (retval == 0) {
1135 				dev->state = STATE_DEV_CONNECTED;
1136 				++dev->udc_usage;
1137 				spin_unlock_irq (&dev->lock);
1138 				if (copy_from_user (dev->req->buf, buf, len))
1139 					retval = -EFAULT;
1140 				else {
1141 					if (len < dev->setup_wLength)
1142 						dev->req->zero = 1;
1143 					retval = usb_ep_queue (
1144 						dev->gadget->ep0, dev->req,
1145 						GFP_KERNEL);
1146 				}
1147 				spin_lock_irq(&dev->lock);
1148 				--dev->udc_usage;
1149 				if (retval < 0) {
1150 					clean_req (dev->gadget->ep0, dev->req);
1151 				} else
1152 					retval = len;
1153 
1154 				return retval;
1155 			}
1156 
1157 		/* can stall some OUT transfers */
1158 		} else if (dev->setup_can_stall) {
1159 			VDEBUG(dev, "ep0out stall\n");
1160 			(void) usb_ep_set_halt (dev->gadget->ep0);
1161 			retval = -EL2HLT;
1162 			dev->state = STATE_DEV_CONNECTED;
1163 		} else {
1164 			DBG(dev, "bogus ep0out stall!\n");
1165 		}
1166 	} else
1167 		DBG (dev, "fail %s, state %d\n", __func__, dev->state);
1168 
1169 	return retval;
1170 }
1171 
1172 static int
1173 ep0_fasync (int f, struct file *fd, int on)
1174 {
1175 	struct dev_data		*dev = fd->private_data;
1176 	// caller must F_SETOWN before signal delivery happens
1177 	VDEBUG (dev, "%s %s\n", __func__, on ? "on" : "off");
1178 	return fasync_helper (f, fd, on, &dev->fasync);
1179 }
1180 
1181 static struct usb_gadget_driver gadgetfs_driver;
1182 
1183 static int
1184 dev_release (struct inode *inode, struct file *fd)
1185 {
1186 	struct dev_data		*dev = fd->private_data;
1187 
1188 	/* closing ep0 === shutdown all */
1189 
1190 	if (dev->gadget_registered) {
1191 		usb_gadget_unregister_driver (&gadgetfs_driver);
1192 		dev->gadget_registered = false;
1193 	}
1194 
1195 	/* at this point "good" hardware has disconnected the
1196 	 * device from USB; the host won't see it any more.
1197 	 * alternatively, all host requests will time out.
1198 	 */
1199 
1200 	kfree (dev->buf);
1201 	dev->buf = NULL;
1202 
1203 	/* other endpoints were all decoupled from this device */
1204 	spin_lock_irq(&dev->lock);
1205 	dev->state = STATE_DEV_DISABLED;
1206 	spin_unlock_irq(&dev->lock);
1207 
1208 	put_dev (dev);
1209 	return 0;
1210 }
1211 
1212 static __poll_t
1213 ep0_poll (struct file *fd, poll_table *wait)
1214 {
1215        struct dev_data         *dev = fd->private_data;
1216        __poll_t                mask = 0;
1217 
1218 	if (dev->state <= STATE_DEV_OPENED)
1219 		return DEFAULT_POLLMASK;
1220 
1221        poll_wait(fd, &dev->wait, wait);
1222 
1223        spin_lock_irq (&dev->lock);
1224 
1225        /* report fd mode change before acting on it */
1226        if (dev->setup_abort) {
1227                dev->setup_abort = 0;
1228                mask = EPOLLHUP;
1229                goto out;
1230        }
1231 
1232        if (dev->state == STATE_DEV_SETUP) {
1233                if (dev->setup_in || dev->setup_can_stall)
1234                        mask = EPOLLOUT;
1235        } else {
1236                if (dev->ev_next != 0)
1237                        mask = EPOLLIN;
1238        }
1239 out:
1240        spin_unlock_irq(&dev->lock);
1241        return mask;
1242 }
1243 
1244 static long dev_ioctl (struct file *fd, unsigned code, unsigned long value)
1245 {
1246 	struct dev_data		*dev = fd->private_data;
1247 	struct usb_gadget	*gadget = dev->gadget;
1248 	long ret = -ENOTTY;
1249 
1250 	spin_lock_irq(&dev->lock);
1251 	if (dev->state == STATE_DEV_OPENED ||
1252 			dev->state == STATE_DEV_UNBOUND) {
1253 		/* Not bound to a UDC */
1254 	} else if (gadget->ops->ioctl) {
1255 		++dev->udc_usage;
1256 		spin_unlock_irq(&dev->lock);
1257 
1258 		ret = gadget->ops->ioctl (gadget, code, value);
1259 
1260 		spin_lock_irq(&dev->lock);
1261 		--dev->udc_usage;
1262 	}
1263 	spin_unlock_irq(&dev->lock);
1264 
1265 	return ret;
1266 }
1267 
1268 /*----------------------------------------------------------------------*/
1269 
1270 /* The in-kernel gadget driver handles most ep0 issues, in particular
1271  * enumerating the single configuration (as provided from user space).
1272  *
1273  * Unrecognized ep0 requests may be handled in user space.
1274  */
1275 
1276 static void make_qualifier (struct dev_data *dev)
1277 {
1278 	struct usb_qualifier_descriptor		qual;
1279 	struct usb_device_descriptor		*desc;
1280 
1281 	qual.bLength = sizeof qual;
1282 	qual.bDescriptorType = USB_DT_DEVICE_QUALIFIER;
1283 	qual.bcdUSB = cpu_to_le16 (0x0200);
1284 
1285 	desc = dev->dev;
1286 	qual.bDeviceClass = desc->bDeviceClass;
1287 	qual.bDeviceSubClass = desc->bDeviceSubClass;
1288 	qual.bDeviceProtocol = desc->bDeviceProtocol;
1289 
1290 	/* assumes ep0 uses the same value for both speeds ... */
1291 	qual.bMaxPacketSize0 = dev->gadget->ep0->maxpacket;
1292 
1293 	qual.bNumConfigurations = 1;
1294 	qual.bRESERVED = 0;
1295 
1296 	memcpy (dev->rbuf, &qual, sizeof qual);
1297 }
1298 
1299 static int
1300 config_buf (struct dev_data *dev, u8 type, unsigned index)
1301 {
1302 	int		len;
1303 	int		hs = 0;
1304 
1305 	/* only one configuration */
1306 	if (index > 0)
1307 		return -EINVAL;
1308 
1309 	if (gadget_is_dualspeed(dev->gadget)) {
1310 		hs = (dev->gadget->speed == USB_SPEED_HIGH);
1311 		if (type == USB_DT_OTHER_SPEED_CONFIG)
1312 			hs = !hs;
1313 	}
1314 	if (hs) {
1315 		dev->req->buf = dev->hs_config;
1316 		len = le16_to_cpu(dev->hs_config->wTotalLength);
1317 	} else {
1318 		dev->req->buf = dev->config;
1319 		len = le16_to_cpu(dev->config->wTotalLength);
1320 	}
1321 	((u8 *)dev->req->buf) [1] = type;
1322 	return len;
1323 }
1324 
1325 static int
1326 gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
1327 {
1328 	struct dev_data			*dev = get_gadget_data (gadget);
1329 	struct usb_request		*req = dev->req;
1330 	int				value = -EOPNOTSUPP;
1331 	struct usb_gadgetfs_event	*event;
1332 	u16				w_value = le16_to_cpu(ctrl->wValue);
1333 	u16				w_length = le16_to_cpu(ctrl->wLength);
1334 
1335 	spin_lock (&dev->lock);
1336 	dev->setup_abort = 0;
1337 	if (dev->state == STATE_DEV_UNCONNECTED) {
1338 		if (gadget_is_dualspeed(gadget)
1339 				&& gadget->speed == USB_SPEED_HIGH
1340 				&& dev->hs_config == NULL) {
1341 			spin_unlock(&dev->lock);
1342 			ERROR (dev, "no high speed config??\n");
1343 			return -EINVAL;
1344 		}
1345 
1346 		dev->state = STATE_DEV_CONNECTED;
1347 
1348 		INFO (dev, "connected\n");
1349 		event = next_event (dev, GADGETFS_CONNECT);
1350 		event->u.speed = gadget->speed;
1351 		ep0_readable (dev);
1352 
1353 	/* host may have given up waiting for response.  we can miss control
1354 	 * requests handled lower down (device/endpoint status and features);
1355 	 * then ep0_{read,write} will report the wrong status. controller
1356 	 * driver will have aborted pending i/o.
1357 	 */
1358 	} else if (dev->state == STATE_DEV_SETUP)
1359 		dev->setup_abort = 1;
1360 
1361 	req->buf = dev->rbuf;
1362 	req->context = NULL;
1363 	value = -EOPNOTSUPP;
1364 	switch (ctrl->bRequest) {
1365 
1366 	case USB_REQ_GET_DESCRIPTOR:
1367 		if (ctrl->bRequestType != USB_DIR_IN)
1368 			goto unrecognized;
1369 		switch (w_value >> 8) {
1370 
1371 		case USB_DT_DEVICE:
1372 			value = min (w_length, (u16) sizeof *dev->dev);
1373 			dev->dev->bMaxPacketSize0 = dev->gadget->ep0->maxpacket;
1374 			req->buf = dev->dev;
1375 			break;
1376 		case USB_DT_DEVICE_QUALIFIER:
1377 			if (!dev->hs_config)
1378 				break;
1379 			value = min (w_length, (u16)
1380 				sizeof (struct usb_qualifier_descriptor));
1381 			make_qualifier (dev);
1382 			break;
1383 		case USB_DT_OTHER_SPEED_CONFIG:
1384 			// FALLTHROUGH
1385 		case USB_DT_CONFIG:
1386 			value = config_buf (dev,
1387 					w_value >> 8,
1388 					w_value & 0xff);
1389 			if (value >= 0)
1390 				value = min (w_length, (u16) value);
1391 			break;
1392 		case USB_DT_STRING:
1393 			goto unrecognized;
1394 
1395 		default:		// all others are errors
1396 			break;
1397 		}
1398 		break;
1399 
1400 	/* currently one config, two speeds */
1401 	case USB_REQ_SET_CONFIGURATION:
1402 		if (ctrl->bRequestType != 0)
1403 			goto unrecognized;
1404 		if (0 == (u8) w_value) {
1405 			value = 0;
1406 			dev->current_config = 0;
1407 			usb_gadget_vbus_draw(gadget, 8 /* mA */ );
1408 			// user mode expected to disable endpoints
1409 		} else {
1410 			u8	config, power;
1411 
1412 			if (gadget_is_dualspeed(gadget)
1413 					&& gadget->speed == USB_SPEED_HIGH) {
1414 				config = dev->hs_config->bConfigurationValue;
1415 				power = dev->hs_config->bMaxPower;
1416 			} else {
1417 				config = dev->config->bConfigurationValue;
1418 				power = dev->config->bMaxPower;
1419 			}
1420 
1421 			if (config == (u8) w_value) {
1422 				value = 0;
1423 				dev->current_config = config;
1424 				usb_gadget_vbus_draw(gadget, 2 * power);
1425 			}
1426 		}
1427 
1428 		/* report SET_CONFIGURATION like any other control request,
1429 		 * except that usermode may not stall this.  the next
1430 		 * request mustn't be allowed start until this finishes:
1431 		 * endpoints and threads set up, etc.
1432 		 *
1433 		 * NOTE:  older PXA hardware (before PXA 255: without UDCCFR)
1434 		 * has bad/racey automagic that prevents synchronizing here.
1435 		 * even kernel mode drivers often miss them.
1436 		 */
1437 		if (value == 0) {
1438 			INFO (dev, "configuration #%d\n", dev->current_config);
1439 			usb_gadget_set_state(gadget, USB_STATE_CONFIGURED);
1440 			if (dev->usermode_setup) {
1441 				dev->setup_can_stall = 0;
1442 				goto delegate;
1443 			}
1444 		}
1445 		break;
1446 
1447 #ifndef	CONFIG_USB_PXA25X
1448 	/* PXA automagically handles this request too */
1449 	case USB_REQ_GET_CONFIGURATION:
1450 		if (ctrl->bRequestType != 0x80)
1451 			goto unrecognized;
1452 		*(u8 *)req->buf = dev->current_config;
1453 		value = min (w_length, (u16) 1);
1454 		break;
1455 #endif
1456 
1457 	default:
1458 unrecognized:
1459 		VDEBUG (dev, "%s req%02x.%02x v%04x i%04x l%d\n",
1460 			dev->usermode_setup ? "delegate" : "fail",
1461 			ctrl->bRequestType, ctrl->bRequest,
1462 			w_value, le16_to_cpu(ctrl->wIndex), w_length);
1463 
1464 		/* if there's an ep0 reader, don't stall */
1465 		if (dev->usermode_setup) {
1466 			dev->setup_can_stall = 1;
1467 delegate:
1468 			dev->setup_in = (ctrl->bRequestType & USB_DIR_IN)
1469 						? 1 : 0;
1470 			dev->setup_wLength = w_length;
1471 			dev->setup_out_ready = 0;
1472 			dev->setup_out_error = 0;
1473 
1474 			/* read DATA stage for OUT right away */
1475 			if (unlikely (!dev->setup_in && w_length)) {
1476 				value = setup_req (gadget->ep0, dev->req,
1477 							w_length);
1478 				if (value < 0)
1479 					break;
1480 
1481 				++dev->udc_usage;
1482 				spin_unlock (&dev->lock);
1483 				value = usb_ep_queue (gadget->ep0, dev->req,
1484 							GFP_KERNEL);
1485 				spin_lock (&dev->lock);
1486 				--dev->udc_usage;
1487 				if (value < 0) {
1488 					clean_req (gadget->ep0, dev->req);
1489 					break;
1490 				}
1491 
1492 				/* we can't currently stall these */
1493 				dev->setup_can_stall = 0;
1494 			}
1495 
1496 			/* state changes when reader collects event */
1497 			event = next_event (dev, GADGETFS_SETUP);
1498 			event->u.setup = *ctrl;
1499 			ep0_readable (dev);
1500 			spin_unlock (&dev->lock);
1501 			return 0;
1502 		}
1503 	}
1504 
1505 	/* proceed with data transfer and status phases? */
1506 	if (value >= 0 && dev->state != STATE_DEV_SETUP) {
1507 		req->length = value;
1508 		req->zero = value < w_length;
1509 
1510 		++dev->udc_usage;
1511 		spin_unlock (&dev->lock);
1512 		value = usb_ep_queue (gadget->ep0, req, GFP_KERNEL);
1513 		spin_lock(&dev->lock);
1514 		--dev->udc_usage;
1515 		spin_unlock(&dev->lock);
1516 		if (value < 0) {
1517 			DBG (dev, "ep_queue --> %d\n", value);
1518 			req->status = 0;
1519 		}
1520 		return value;
1521 	}
1522 
1523 	/* device stalls when value < 0 */
1524 	spin_unlock (&dev->lock);
1525 	return value;
1526 }
1527 
1528 static void destroy_ep_files (struct dev_data *dev)
1529 {
1530 	DBG (dev, "%s %d\n", __func__, dev->state);
1531 
1532 	/* dev->state must prevent interference */
1533 	spin_lock_irq (&dev->lock);
1534 	while (!list_empty(&dev->epfiles)) {
1535 		struct ep_data	*ep;
1536 		struct inode	*parent;
1537 		struct dentry	*dentry;
1538 
1539 		/* break link to FS */
1540 		ep = list_first_entry (&dev->epfiles, struct ep_data, epfiles);
1541 		list_del_init (&ep->epfiles);
1542 		spin_unlock_irq (&dev->lock);
1543 
1544 		dentry = ep->dentry;
1545 		ep->dentry = NULL;
1546 		parent = d_inode(dentry->d_parent);
1547 
1548 		/* break link to controller */
1549 		mutex_lock(&ep->lock);
1550 		if (ep->state == STATE_EP_ENABLED)
1551 			(void) usb_ep_disable (ep->ep);
1552 		ep->state = STATE_EP_UNBOUND;
1553 		usb_ep_free_request (ep->ep, ep->req);
1554 		ep->ep = NULL;
1555 		mutex_unlock(&ep->lock);
1556 
1557 		wake_up (&ep->wait);
1558 		put_ep (ep);
1559 
1560 		/* break link to dcache */
1561 		inode_lock(parent);
1562 		d_delete (dentry);
1563 		dput (dentry);
1564 		inode_unlock(parent);
1565 
1566 		spin_lock_irq (&dev->lock);
1567 	}
1568 	spin_unlock_irq (&dev->lock);
1569 }
1570 
1571 
1572 static struct dentry *
1573 gadgetfs_create_file (struct super_block *sb, char const *name,
1574 		void *data, const struct file_operations *fops);
1575 
1576 static int activate_ep_files (struct dev_data *dev)
1577 {
1578 	struct usb_ep	*ep;
1579 	struct ep_data	*data;
1580 
1581 	gadget_for_each_ep (ep, dev->gadget) {
1582 
1583 		data = kzalloc(sizeof(*data), GFP_KERNEL);
1584 		if (!data)
1585 			goto enomem0;
1586 		data->state = STATE_EP_DISABLED;
1587 		mutex_init(&data->lock);
1588 		init_waitqueue_head (&data->wait);
1589 
1590 		strncpy (data->name, ep->name, sizeof (data->name) - 1);
1591 		refcount_set (&data->count, 1);
1592 		data->dev = dev;
1593 		get_dev (dev);
1594 
1595 		data->ep = ep;
1596 		ep->driver_data = data;
1597 
1598 		data->req = usb_ep_alloc_request (ep, GFP_KERNEL);
1599 		if (!data->req)
1600 			goto enomem1;
1601 
1602 		data->dentry = gadgetfs_create_file (dev->sb, data->name,
1603 				data, &ep_io_operations);
1604 		if (!data->dentry)
1605 			goto enomem2;
1606 		list_add_tail (&data->epfiles, &dev->epfiles);
1607 	}
1608 	return 0;
1609 
1610 enomem2:
1611 	usb_ep_free_request (ep, data->req);
1612 enomem1:
1613 	put_dev (dev);
1614 	kfree (data);
1615 enomem0:
1616 	DBG (dev, "%s enomem\n", __func__);
1617 	destroy_ep_files (dev);
1618 	return -ENOMEM;
1619 }
1620 
1621 static void
1622 gadgetfs_unbind (struct usb_gadget *gadget)
1623 {
1624 	struct dev_data		*dev = get_gadget_data (gadget);
1625 
1626 	DBG (dev, "%s\n", __func__);
1627 
1628 	spin_lock_irq (&dev->lock);
1629 	dev->state = STATE_DEV_UNBOUND;
1630 	while (dev->udc_usage > 0) {
1631 		spin_unlock_irq(&dev->lock);
1632 		usleep_range(1000, 2000);
1633 		spin_lock_irq(&dev->lock);
1634 	}
1635 	spin_unlock_irq (&dev->lock);
1636 
1637 	destroy_ep_files (dev);
1638 	gadget->ep0->driver_data = NULL;
1639 	set_gadget_data (gadget, NULL);
1640 
1641 	/* we've already been disconnected ... no i/o is active */
1642 	if (dev->req)
1643 		usb_ep_free_request (gadget->ep0, dev->req);
1644 	DBG (dev, "%s done\n", __func__);
1645 	put_dev (dev);
1646 }
1647 
1648 static struct dev_data		*the_device;
1649 
1650 static int gadgetfs_bind(struct usb_gadget *gadget,
1651 		struct usb_gadget_driver *driver)
1652 {
1653 	struct dev_data		*dev = the_device;
1654 
1655 	if (!dev)
1656 		return -ESRCH;
1657 	if (0 != strcmp (CHIP, gadget->name)) {
1658 		pr_err("%s expected %s controller not %s\n",
1659 			shortname, CHIP, gadget->name);
1660 		return -ENODEV;
1661 	}
1662 
1663 	set_gadget_data (gadget, dev);
1664 	dev->gadget = gadget;
1665 	gadget->ep0->driver_data = dev;
1666 
1667 	/* preallocate control response and buffer */
1668 	dev->req = usb_ep_alloc_request (gadget->ep0, GFP_KERNEL);
1669 	if (!dev->req)
1670 		goto enomem;
1671 	dev->req->context = NULL;
1672 	dev->req->complete = epio_complete;
1673 
1674 	if (activate_ep_files (dev) < 0)
1675 		goto enomem;
1676 
1677 	INFO (dev, "bound to %s driver\n", gadget->name);
1678 	spin_lock_irq(&dev->lock);
1679 	dev->state = STATE_DEV_UNCONNECTED;
1680 	spin_unlock_irq(&dev->lock);
1681 	get_dev (dev);
1682 	return 0;
1683 
1684 enomem:
1685 	gadgetfs_unbind (gadget);
1686 	return -ENOMEM;
1687 }
1688 
1689 static void
1690 gadgetfs_disconnect (struct usb_gadget *gadget)
1691 {
1692 	struct dev_data		*dev = get_gadget_data (gadget);
1693 	unsigned long		flags;
1694 
1695 	spin_lock_irqsave (&dev->lock, flags);
1696 	if (dev->state == STATE_DEV_UNCONNECTED)
1697 		goto exit;
1698 	dev->state = STATE_DEV_UNCONNECTED;
1699 
1700 	INFO (dev, "disconnected\n");
1701 	next_event (dev, GADGETFS_DISCONNECT);
1702 	ep0_readable (dev);
1703 exit:
1704 	spin_unlock_irqrestore (&dev->lock, flags);
1705 }
1706 
1707 static void
1708 gadgetfs_suspend (struct usb_gadget *gadget)
1709 {
1710 	struct dev_data		*dev = get_gadget_data (gadget);
1711 	unsigned long		flags;
1712 
1713 	INFO (dev, "suspended from state %d\n", dev->state);
1714 	spin_lock_irqsave(&dev->lock, flags);
1715 	switch (dev->state) {
1716 	case STATE_DEV_SETUP:		// VERY odd... host died??
1717 	case STATE_DEV_CONNECTED:
1718 	case STATE_DEV_UNCONNECTED:
1719 		next_event (dev, GADGETFS_SUSPEND);
1720 		ep0_readable (dev);
1721 		/* FALLTHROUGH */
1722 	default:
1723 		break;
1724 	}
1725 	spin_unlock_irqrestore(&dev->lock, flags);
1726 }
1727 
1728 static struct usb_gadget_driver gadgetfs_driver = {
1729 	.function	= (char *) driver_desc,
1730 	.bind		= gadgetfs_bind,
1731 	.unbind		= gadgetfs_unbind,
1732 	.setup		= gadgetfs_setup,
1733 	.reset		= gadgetfs_disconnect,
1734 	.disconnect	= gadgetfs_disconnect,
1735 	.suspend	= gadgetfs_suspend,
1736 
1737 	.driver	= {
1738 		.name		= (char *) shortname,
1739 	},
1740 };
1741 
1742 /*----------------------------------------------------------------------*/
1743 /* DEVICE INITIALIZATION
1744  *
1745  *     fd = open ("/dev/gadget/$CHIP", O_RDWR)
1746  *     status = write (fd, descriptors, sizeof descriptors)
1747  *
1748  * That write establishes the device configuration, so the kernel can
1749  * bind to the controller ... guaranteeing it can handle enumeration
1750  * at all necessary speeds.  Descriptor order is:
1751  *
1752  * . message tag (u32, host order) ... for now, must be zero; it
1753  *	would change to support features like multi-config devices
1754  * . full/low speed config ... all wTotalLength bytes (with interface,
1755  *	class, altsetting, endpoint, and other descriptors)
1756  * . high speed config ... all descriptors, for high speed operation;
1757  *	this one's optional except for high-speed hardware
1758  * . device descriptor
1759  *
1760  * Endpoints are not yet enabled. Drivers must wait until device
1761  * configuration and interface altsetting changes create
1762  * the need to configure (or unconfigure) them.
1763  *
1764  * After initialization, the device stays active for as long as that
1765  * $CHIP file is open.  Events must then be read from that descriptor,
1766  * such as configuration notifications.
1767  */
1768 
1769 static int is_valid_config(struct usb_config_descriptor *config,
1770 		unsigned int total)
1771 {
1772 	return config->bDescriptorType == USB_DT_CONFIG
1773 		&& config->bLength == USB_DT_CONFIG_SIZE
1774 		&& total >= USB_DT_CONFIG_SIZE
1775 		&& config->bConfigurationValue != 0
1776 		&& (config->bmAttributes & USB_CONFIG_ATT_ONE) != 0
1777 		&& (config->bmAttributes & USB_CONFIG_ATT_WAKEUP) == 0;
1778 	/* FIXME if gadget->is_otg, _must_ include an otg descriptor */
1779 	/* FIXME check lengths: walk to end */
1780 }
1781 
1782 static ssize_t
1783 dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
1784 {
1785 	struct dev_data		*dev = fd->private_data;
1786 	ssize_t			value = len, length = len;
1787 	unsigned		total;
1788 	u32			tag;
1789 	char			*kbuf;
1790 
1791 	spin_lock_irq(&dev->lock);
1792 	if (dev->state > STATE_DEV_OPENED) {
1793 		value = ep0_write(fd, buf, len, ptr);
1794 		spin_unlock_irq(&dev->lock);
1795 		return value;
1796 	}
1797 	spin_unlock_irq(&dev->lock);
1798 
1799 	if ((len < (USB_DT_CONFIG_SIZE + USB_DT_DEVICE_SIZE + 4)) ||
1800 	    (len > PAGE_SIZE * 4))
1801 		return -EINVAL;
1802 
1803 	/* we might need to change message format someday */
1804 	if (copy_from_user (&tag, buf, 4))
1805 		return -EFAULT;
1806 	if (tag != 0)
1807 		return -EINVAL;
1808 	buf += 4;
1809 	length -= 4;
1810 
1811 	kbuf = memdup_user(buf, length);
1812 	if (IS_ERR(kbuf))
1813 		return PTR_ERR(kbuf);
1814 
1815 	spin_lock_irq (&dev->lock);
1816 	value = -EINVAL;
1817 	if (dev->buf) {
1818 		kfree(kbuf);
1819 		goto fail;
1820 	}
1821 	dev->buf = kbuf;
1822 
1823 	/* full or low speed config */
1824 	dev->config = (void *) kbuf;
1825 	total = le16_to_cpu(dev->config->wTotalLength);
1826 	if (!is_valid_config(dev->config, total) ||
1827 			total > length - USB_DT_DEVICE_SIZE)
1828 		goto fail;
1829 	kbuf += total;
1830 	length -= total;
1831 
1832 	/* optional high speed config */
1833 	if (kbuf [1] == USB_DT_CONFIG) {
1834 		dev->hs_config = (void *) kbuf;
1835 		total = le16_to_cpu(dev->hs_config->wTotalLength);
1836 		if (!is_valid_config(dev->hs_config, total) ||
1837 				total > length - USB_DT_DEVICE_SIZE)
1838 			goto fail;
1839 		kbuf += total;
1840 		length -= total;
1841 	} else {
1842 		dev->hs_config = NULL;
1843 	}
1844 
1845 	/* could support multiple configs, using another encoding! */
1846 
1847 	/* device descriptor (tweaked for paranoia) */
1848 	if (length != USB_DT_DEVICE_SIZE)
1849 		goto fail;
1850 	dev->dev = (void *)kbuf;
1851 	if (dev->dev->bLength != USB_DT_DEVICE_SIZE
1852 			|| dev->dev->bDescriptorType != USB_DT_DEVICE
1853 			|| dev->dev->bNumConfigurations != 1)
1854 		goto fail;
1855 	dev->dev->bcdUSB = cpu_to_le16 (0x0200);
1856 
1857 	/* triggers gadgetfs_bind(); then we can enumerate. */
1858 	spin_unlock_irq (&dev->lock);
1859 	if (dev->hs_config)
1860 		gadgetfs_driver.max_speed = USB_SPEED_HIGH;
1861 	else
1862 		gadgetfs_driver.max_speed = USB_SPEED_FULL;
1863 
1864 	value = usb_gadget_probe_driver(&gadgetfs_driver);
1865 	if (value != 0) {
1866 		kfree (dev->buf);
1867 		dev->buf = NULL;
1868 	} else {
1869 		/* at this point "good" hardware has for the first time
1870 		 * let the USB the host see us.  alternatively, if users
1871 		 * unplug/replug that will clear all the error state.
1872 		 *
1873 		 * note:  everything running before here was guaranteed
1874 		 * to choke driver model style diagnostics.  from here
1875 		 * on, they can work ... except in cleanup paths that
1876 		 * kick in after the ep0 descriptor is closed.
1877 		 */
1878 		value = len;
1879 		dev->gadget_registered = true;
1880 	}
1881 	return value;
1882 
1883 fail:
1884 	spin_unlock_irq (&dev->lock);
1885 	pr_debug ("%s: %s fail %zd, %p\n", shortname, __func__, value, dev);
1886 	kfree (dev->buf);
1887 	dev->buf = NULL;
1888 	return value;
1889 }
1890 
1891 static int
1892 dev_open (struct inode *inode, struct file *fd)
1893 {
1894 	struct dev_data		*dev = inode->i_private;
1895 	int			value = -EBUSY;
1896 
1897 	spin_lock_irq(&dev->lock);
1898 	if (dev->state == STATE_DEV_DISABLED) {
1899 		dev->ev_next = 0;
1900 		dev->state = STATE_DEV_OPENED;
1901 		fd->private_data = dev;
1902 		get_dev (dev);
1903 		value = 0;
1904 	}
1905 	spin_unlock_irq(&dev->lock);
1906 	return value;
1907 }
1908 
1909 static const struct file_operations ep0_operations = {
1910 	.llseek =	no_llseek,
1911 
1912 	.open =		dev_open,
1913 	.read =		ep0_read,
1914 	.write =	dev_config,
1915 	.fasync =	ep0_fasync,
1916 	.poll =		ep0_poll,
1917 	.unlocked_ioctl = dev_ioctl,
1918 	.release =	dev_release,
1919 };
1920 
1921 /*----------------------------------------------------------------------*/
1922 
1923 /* FILESYSTEM AND SUPERBLOCK OPERATIONS
1924  *
1925  * Mounting the filesystem creates a controller file, used first for
1926  * device configuration then later for event monitoring.
1927  */
1928 
1929 
1930 /* FIXME PAM etc could set this security policy without mount options
1931  * if epfiles inherited ownership and permissons from ep0 ...
1932  */
1933 
1934 static unsigned default_uid;
1935 static unsigned default_gid;
1936 static unsigned default_perm = S_IRUSR | S_IWUSR;
1937 
1938 module_param (default_uid, uint, 0644);
1939 module_param (default_gid, uint, 0644);
1940 module_param (default_perm, uint, 0644);
1941 
1942 
1943 static struct inode *
1944 gadgetfs_make_inode (struct super_block *sb,
1945 		void *data, const struct file_operations *fops,
1946 		int mode)
1947 {
1948 	struct inode *inode = new_inode (sb);
1949 
1950 	if (inode) {
1951 		inode->i_ino = get_next_ino();
1952 		inode->i_mode = mode;
1953 		inode->i_uid = make_kuid(&init_user_ns, default_uid);
1954 		inode->i_gid = make_kgid(&init_user_ns, default_gid);
1955 		inode->i_atime = inode->i_mtime = inode->i_ctime
1956 				= current_time(inode);
1957 		inode->i_private = data;
1958 		inode->i_fop = fops;
1959 	}
1960 	return inode;
1961 }
1962 
1963 /* creates in fs root directory, so non-renamable and non-linkable.
1964  * so inode and dentry are paired, until device reconfig.
1965  */
1966 static struct dentry *
1967 gadgetfs_create_file (struct super_block *sb, char const *name,
1968 		void *data, const struct file_operations *fops)
1969 {
1970 	struct dentry	*dentry;
1971 	struct inode	*inode;
1972 
1973 	dentry = d_alloc_name(sb->s_root, name);
1974 	if (!dentry)
1975 		return NULL;
1976 
1977 	inode = gadgetfs_make_inode (sb, data, fops,
1978 			S_IFREG | (default_perm & S_IRWXUGO));
1979 	if (!inode) {
1980 		dput(dentry);
1981 		return NULL;
1982 	}
1983 	d_add (dentry, inode);
1984 	return dentry;
1985 }
1986 
1987 static const struct super_operations gadget_fs_operations = {
1988 	.statfs =	simple_statfs,
1989 	.drop_inode =	generic_delete_inode,
1990 };
1991 
1992 static int
1993 gadgetfs_fill_super (struct super_block *sb, void *opts, int silent)
1994 {
1995 	struct inode	*inode;
1996 	struct dev_data	*dev;
1997 
1998 	if (the_device)
1999 		return -ESRCH;
2000 
2001 	CHIP = usb_get_gadget_udc_name();
2002 	if (!CHIP)
2003 		return -ENODEV;
2004 
2005 	/* superblock */
2006 	sb->s_blocksize = PAGE_SIZE;
2007 	sb->s_blocksize_bits = PAGE_SHIFT;
2008 	sb->s_magic = GADGETFS_MAGIC;
2009 	sb->s_op = &gadget_fs_operations;
2010 	sb->s_time_gran = 1;
2011 
2012 	/* root inode */
2013 	inode = gadgetfs_make_inode (sb,
2014 			NULL, &simple_dir_operations,
2015 			S_IFDIR | S_IRUGO | S_IXUGO);
2016 	if (!inode)
2017 		goto Enomem;
2018 	inode->i_op = &simple_dir_inode_operations;
2019 	if (!(sb->s_root = d_make_root (inode)))
2020 		goto Enomem;
2021 
2022 	/* the ep0 file is named after the controller we expect;
2023 	 * user mode code can use it for sanity checks, like we do.
2024 	 */
2025 	dev = dev_new ();
2026 	if (!dev)
2027 		goto Enomem;
2028 
2029 	dev->sb = sb;
2030 	dev->dentry = gadgetfs_create_file(sb, CHIP, dev, &ep0_operations);
2031 	if (!dev->dentry) {
2032 		put_dev(dev);
2033 		goto Enomem;
2034 	}
2035 
2036 	/* other endpoint files are available after hardware setup,
2037 	 * from binding to a controller.
2038 	 */
2039 	the_device = dev;
2040 	return 0;
2041 
2042 Enomem:
2043 	return -ENOMEM;
2044 }
2045 
2046 /* "mount -t gadgetfs path /dev/gadget" ends up here */
2047 static struct dentry *
2048 gadgetfs_mount (struct file_system_type *t, int flags,
2049 		const char *path, void *opts)
2050 {
2051 	return mount_single (t, flags, opts, gadgetfs_fill_super);
2052 }
2053 
2054 static void
2055 gadgetfs_kill_sb (struct super_block *sb)
2056 {
2057 	kill_litter_super (sb);
2058 	if (the_device) {
2059 		put_dev (the_device);
2060 		the_device = NULL;
2061 	}
2062 	kfree(CHIP);
2063 	CHIP = NULL;
2064 }
2065 
2066 /*----------------------------------------------------------------------*/
2067 
2068 static struct file_system_type gadgetfs_type = {
2069 	.owner		= THIS_MODULE,
2070 	.name		= shortname,
2071 	.mount		= gadgetfs_mount,
2072 	.kill_sb	= gadgetfs_kill_sb,
2073 };
2074 MODULE_ALIAS_FS("gadgetfs");
2075 
2076 /*----------------------------------------------------------------------*/
2077 
2078 static int __init init (void)
2079 {
2080 	int status;
2081 
2082 	status = register_filesystem (&gadgetfs_type);
2083 	if (status == 0)
2084 		pr_info ("%s: %s, version " DRIVER_VERSION "\n",
2085 			shortname, driver_desc);
2086 	return status;
2087 }
2088 module_init (init);
2089 
2090 static void __exit cleanup (void)
2091 {
2092 	pr_debug ("unregister %s\n", shortname);
2093 	unregister_filesystem (&gadgetfs_type);
2094 }
2095 module_exit (cleanup);
2096 
2097