xref: /openbmc/linux/drivers/hid/uhid.c (revision 3e26a691)
1 /*
2  * User-space I/O driver support for HID subsystem
3  * Copyright (c) 2012 David Herrmann
4  */
5 
6 /*
7  * This program is free software; you can redistribute it and/or modify it
8  * under the terms of the GNU General Public License as published by the Free
9  * Software Foundation; either version 2 of the License, or (at your option)
10  * any later version.
11  */
12 
13 #include <linux/atomic.h>
14 #include <linux/compat.h>
15 #include <linux/device.h>
16 #include <linux/fs.h>
17 #include <linux/hid.h>
18 #include <linux/input.h>
19 #include <linux/miscdevice.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/poll.h>
23 #include <linux/sched.h>
24 #include <linux/spinlock.h>
25 #include <linux/uhid.h>
26 #include <linux/wait.h>
27 
28 #define UHID_NAME	"uhid"
29 #define UHID_BUFSIZE	32
30 
31 struct uhid_device {
32 	struct mutex devlock;
33 	bool running;
34 
35 	__u8 *rd_data;
36 	uint rd_size;
37 
38 	struct hid_device *hid;
39 	struct uhid_event input_buf;
40 
41 	wait_queue_head_t waitq;
42 	spinlock_t qlock;
43 	__u8 head;
44 	__u8 tail;
45 	struct uhid_event *outq[UHID_BUFSIZE];
46 
47 	/* blocking GET_REPORT support; state changes protected by qlock */
48 	struct mutex report_lock;
49 	wait_queue_head_t report_wait;
50 	bool report_running;
51 	u32 report_id;
52 	u32 report_type;
53 	struct uhid_event report_buf;
54 };
55 
56 static struct miscdevice uhid_misc;
57 
58 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
59 {
60 	__u8 newhead;
61 
62 	newhead = (uhid->head + 1) % UHID_BUFSIZE;
63 
64 	if (newhead != uhid->tail) {
65 		uhid->outq[uhid->head] = ev;
66 		uhid->head = newhead;
67 		wake_up_interruptible(&uhid->waitq);
68 	} else {
69 		hid_warn(uhid->hid, "Output queue is full\n");
70 		kfree(ev);
71 	}
72 }
73 
74 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
75 {
76 	unsigned long flags;
77 	struct uhid_event *ev;
78 
79 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
80 	if (!ev)
81 		return -ENOMEM;
82 
83 	ev->type = event;
84 
85 	spin_lock_irqsave(&uhid->qlock, flags);
86 	uhid_queue(uhid, ev);
87 	spin_unlock_irqrestore(&uhid->qlock, flags);
88 
89 	return 0;
90 }
91 
92 static int uhid_hid_start(struct hid_device *hid)
93 {
94 	struct uhid_device *uhid = hid->driver_data;
95 	struct uhid_event *ev;
96 	unsigned long flags;
97 
98 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
99 	if (!ev)
100 		return -ENOMEM;
101 
102 	ev->type = UHID_START;
103 
104 	if (hid->report_enum[HID_FEATURE_REPORT].numbered)
105 		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS;
106 	if (hid->report_enum[HID_OUTPUT_REPORT].numbered)
107 		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS;
108 	if (hid->report_enum[HID_INPUT_REPORT].numbered)
109 		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS;
110 
111 	spin_lock_irqsave(&uhid->qlock, flags);
112 	uhid_queue(uhid, ev);
113 	spin_unlock_irqrestore(&uhid->qlock, flags);
114 
115 	return 0;
116 }
117 
118 static void uhid_hid_stop(struct hid_device *hid)
119 {
120 	struct uhid_device *uhid = hid->driver_data;
121 
122 	hid->claimed = 0;
123 	uhid_queue_event(uhid, UHID_STOP);
124 }
125 
126 static int uhid_hid_open(struct hid_device *hid)
127 {
128 	struct uhid_device *uhid = hid->driver_data;
129 
130 	return uhid_queue_event(uhid, UHID_OPEN);
131 }
132 
133 static void uhid_hid_close(struct hid_device *hid)
134 {
135 	struct uhid_device *uhid = hid->driver_data;
136 
137 	uhid_queue_event(uhid, UHID_CLOSE);
138 }
139 
140 static int uhid_hid_parse(struct hid_device *hid)
141 {
142 	struct uhid_device *uhid = hid->driver_data;
143 
144 	return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
145 }
146 
147 /* must be called with report_lock held */
148 static int __uhid_report_queue_and_wait(struct uhid_device *uhid,
149 					struct uhid_event *ev,
150 					__u32 *report_id)
151 {
152 	unsigned long flags;
153 	int ret;
154 
155 	spin_lock_irqsave(&uhid->qlock, flags);
156 	*report_id = ++uhid->report_id;
157 	uhid->report_type = ev->type + 1;
158 	uhid->report_running = true;
159 	uhid_queue(uhid, ev);
160 	spin_unlock_irqrestore(&uhid->qlock, flags);
161 
162 	ret = wait_event_interruptible_timeout(uhid->report_wait,
163 				!uhid->report_running || !uhid->running,
164 				5 * HZ);
165 	if (!ret || !uhid->running || uhid->report_running)
166 		ret = -EIO;
167 	else if (ret < 0)
168 		ret = -ERESTARTSYS;
169 	else
170 		ret = 0;
171 
172 	uhid->report_running = false;
173 
174 	return ret;
175 }
176 
177 static void uhid_report_wake_up(struct uhid_device *uhid, u32 id,
178 				const struct uhid_event *ev)
179 {
180 	unsigned long flags;
181 
182 	spin_lock_irqsave(&uhid->qlock, flags);
183 
184 	/* id for old report; drop it silently */
185 	if (uhid->report_type != ev->type || uhid->report_id != id)
186 		goto unlock;
187 	if (!uhid->report_running)
188 		goto unlock;
189 
190 	memcpy(&uhid->report_buf, ev, sizeof(*ev));
191 	uhid->report_running = false;
192 	wake_up_interruptible(&uhid->report_wait);
193 
194 unlock:
195 	spin_unlock_irqrestore(&uhid->qlock, flags);
196 }
197 
198 static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum,
199 			       u8 *buf, size_t count, u8 rtype)
200 {
201 	struct uhid_device *uhid = hid->driver_data;
202 	struct uhid_get_report_reply_req *req;
203 	struct uhid_event *ev;
204 	int ret;
205 
206 	if (!uhid->running)
207 		return -EIO;
208 
209 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
210 	if (!ev)
211 		return -ENOMEM;
212 
213 	ev->type = UHID_GET_REPORT;
214 	ev->u.get_report.rnum = rnum;
215 	ev->u.get_report.rtype = rtype;
216 
217 	ret = mutex_lock_interruptible(&uhid->report_lock);
218 	if (ret) {
219 		kfree(ev);
220 		return ret;
221 	}
222 
223 	/* this _always_ takes ownership of @ev */
224 	ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.get_report.id);
225 	if (ret)
226 		goto unlock;
227 
228 	req = &uhid->report_buf.u.get_report_reply;
229 	if (req->err) {
230 		ret = -EIO;
231 	} else {
232 		ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX);
233 		memcpy(buf, req->data, ret);
234 	}
235 
236 unlock:
237 	mutex_unlock(&uhid->report_lock);
238 	return ret;
239 }
240 
241 static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum,
242 			       const u8 *buf, size_t count, u8 rtype)
243 {
244 	struct uhid_device *uhid = hid->driver_data;
245 	struct uhid_event *ev;
246 	int ret;
247 
248 	if (!uhid->running || count > UHID_DATA_MAX)
249 		return -EIO;
250 
251 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
252 	if (!ev)
253 		return -ENOMEM;
254 
255 	ev->type = UHID_SET_REPORT;
256 	ev->u.set_report.rnum = rnum;
257 	ev->u.set_report.rtype = rtype;
258 	ev->u.set_report.size = count;
259 	memcpy(ev->u.set_report.data, buf, count);
260 
261 	ret = mutex_lock_interruptible(&uhid->report_lock);
262 	if (ret) {
263 		kfree(ev);
264 		return ret;
265 	}
266 
267 	/* this _always_ takes ownership of @ev */
268 	ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.set_report.id);
269 	if (ret)
270 		goto unlock;
271 
272 	if (uhid->report_buf.u.set_report_reply.err)
273 		ret = -EIO;
274 	else
275 		ret = count;
276 
277 unlock:
278 	mutex_unlock(&uhid->report_lock);
279 	return ret;
280 }
281 
282 static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum,
283 				__u8 *buf, size_t len, unsigned char rtype,
284 				int reqtype)
285 {
286 	u8 u_rtype;
287 
288 	switch (rtype) {
289 	case HID_FEATURE_REPORT:
290 		u_rtype = UHID_FEATURE_REPORT;
291 		break;
292 	case HID_OUTPUT_REPORT:
293 		u_rtype = UHID_OUTPUT_REPORT;
294 		break;
295 	case HID_INPUT_REPORT:
296 		u_rtype = UHID_INPUT_REPORT;
297 		break;
298 	default:
299 		return -EINVAL;
300 	}
301 
302 	switch (reqtype) {
303 	case HID_REQ_GET_REPORT:
304 		return uhid_hid_get_report(hid, reportnum, buf, len, u_rtype);
305 	case HID_REQ_SET_REPORT:
306 		return uhid_hid_set_report(hid, reportnum, buf, len, u_rtype);
307 	default:
308 		return -EIO;
309 	}
310 }
311 
312 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
313 			       unsigned char report_type)
314 {
315 	struct uhid_device *uhid = hid->driver_data;
316 	__u8 rtype;
317 	unsigned long flags;
318 	struct uhid_event *ev;
319 
320 	switch (report_type) {
321 	case HID_FEATURE_REPORT:
322 		rtype = UHID_FEATURE_REPORT;
323 		break;
324 	case HID_OUTPUT_REPORT:
325 		rtype = UHID_OUTPUT_REPORT;
326 		break;
327 	default:
328 		return -EINVAL;
329 	}
330 
331 	if (count < 1 || count > UHID_DATA_MAX)
332 		return -EINVAL;
333 
334 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
335 	if (!ev)
336 		return -ENOMEM;
337 
338 	ev->type = UHID_OUTPUT;
339 	ev->u.output.size = count;
340 	ev->u.output.rtype = rtype;
341 	memcpy(ev->u.output.data, buf, count);
342 
343 	spin_lock_irqsave(&uhid->qlock, flags);
344 	uhid_queue(uhid, ev);
345 	spin_unlock_irqrestore(&uhid->qlock, flags);
346 
347 	return count;
348 }
349 
350 static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf,
351 				  size_t count)
352 {
353 	return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT);
354 }
355 
356 static struct hid_ll_driver uhid_hid_driver = {
357 	.start = uhid_hid_start,
358 	.stop = uhid_hid_stop,
359 	.open = uhid_hid_open,
360 	.close = uhid_hid_close,
361 	.parse = uhid_hid_parse,
362 	.raw_request = uhid_hid_raw_request,
363 	.output_report = uhid_hid_output_report,
364 };
365 
366 #ifdef CONFIG_COMPAT
367 
368 /* Apparently we haven't stepped on these rakes enough times yet. */
369 struct uhid_create_req_compat {
370 	__u8 name[128];
371 	__u8 phys[64];
372 	__u8 uniq[64];
373 
374 	compat_uptr_t rd_data;
375 	__u16 rd_size;
376 
377 	__u16 bus;
378 	__u32 vendor;
379 	__u32 product;
380 	__u32 version;
381 	__u32 country;
382 } __attribute__((__packed__));
383 
384 static int uhid_event_from_user(const char __user *buffer, size_t len,
385 				struct uhid_event *event)
386 {
387 	if (in_compat_syscall()) {
388 		u32 type;
389 
390 		if (get_user(type, buffer))
391 			return -EFAULT;
392 
393 		if (type == UHID_CREATE) {
394 			/*
395 			 * This is our messed up request with compat pointer.
396 			 * It is largish (more than 256 bytes) so we better
397 			 * allocate it from the heap.
398 			 */
399 			struct uhid_create_req_compat *compat;
400 
401 			compat = kzalloc(sizeof(*compat), GFP_KERNEL);
402 			if (!compat)
403 				return -ENOMEM;
404 
405 			buffer += sizeof(type);
406 			len -= sizeof(type);
407 			if (copy_from_user(compat, buffer,
408 					   min(len, sizeof(*compat)))) {
409 				kfree(compat);
410 				return -EFAULT;
411 			}
412 
413 			/* Shuffle the data over to proper structure */
414 			event->type = type;
415 
416 			memcpy(event->u.create.name, compat->name,
417 				sizeof(compat->name));
418 			memcpy(event->u.create.phys, compat->phys,
419 				sizeof(compat->phys));
420 			memcpy(event->u.create.uniq, compat->uniq,
421 				sizeof(compat->uniq));
422 
423 			event->u.create.rd_data = compat_ptr(compat->rd_data);
424 			event->u.create.rd_size = compat->rd_size;
425 
426 			event->u.create.bus = compat->bus;
427 			event->u.create.vendor = compat->vendor;
428 			event->u.create.product = compat->product;
429 			event->u.create.version = compat->version;
430 			event->u.create.country = compat->country;
431 
432 			kfree(compat);
433 			return 0;
434 		}
435 		/* All others can be copied directly */
436 	}
437 
438 	if (copy_from_user(event, buffer, min(len, sizeof(*event))))
439 		return -EFAULT;
440 
441 	return 0;
442 }
443 #else
444 static int uhid_event_from_user(const char __user *buffer, size_t len,
445 				struct uhid_event *event)
446 {
447 	if (copy_from_user(event, buffer, min(len, sizeof(*event))))
448 		return -EFAULT;
449 
450 	return 0;
451 }
452 #endif
453 
454 static int uhid_dev_create2(struct uhid_device *uhid,
455 			    const struct uhid_event *ev)
456 {
457 	struct hid_device *hid;
458 	size_t rd_size, len;
459 	void *rd_data;
460 	int ret;
461 
462 	if (uhid->running)
463 		return -EALREADY;
464 
465 	rd_size = ev->u.create2.rd_size;
466 	if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE)
467 		return -EINVAL;
468 
469 	rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL);
470 	if (!rd_data)
471 		return -ENOMEM;
472 
473 	uhid->rd_size = rd_size;
474 	uhid->rd_data = rd_data;
475 
476 	hid = hid_allocate_device();
477 	if (IS_ERR(hid)) {
478 		ret = PTR_ERR(hid);
479 		goto err_free;
480 	}
481 
482 	len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1;
483 	strncpy(hid->name, ev->u.create2.name, len);
484 	len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1;
485 	strncpy(hid->phys, ev->u.create2.phys, len);
486 	len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1;
487 	strncpy(hid->uniq, ev->u.create2.uniq, len);
488 
489 	hid->ll_driver = &uhid_hid_driver;
490 	hid->bus = ev->u.create2.bus;
491 	hid->vendor = ev->u.create2.vendor;
492 	hid->product = ev->u.create2.product;
493 	hid->version = ev->u.create2.version;
494 	hid->country = ev->u.create2.country;
495 	hid->driver_data = uhid;
496 	hid->dev.parent = uhid_misc.this_device;
497 
498 	uhid->hid = hid;
499 	uhid->running = true;
500 
501 	ret = hid_add_device(hid);
502 	if (ret) {
503 		hid_err(hid, "Cannot register HID device\n");
504 		goto err_hid;
505 	}
506 
507 	return 0;
508 
509 err_hid:
510 	hid_destroy_device(hid);
511 	uhid->hid = NULL;
512 	uhid->running = false;
513 err_free:
514 	kfree(uhid->rd_data);
515 	uhid->rd_data = NULL;
516 	uhid->rd_size = 0;
517 	return ret;
518 }
519 
520 static int uhid_dev_create(struct uhid_device *uhid,
521 			   struct uhid_event *ev)
522 {
523 	struct uhid_create_req orig;
524 
525 	orig = ev->u.create;
526 
527 	if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE)
528 		return -EINVAL;
529 	if (copy_from_user(&ev->u.create2.rd_data, orig.rd_data, orig.rd_size))
530 		return -EFAULT;
531 
532 	memcpy(ev->u.create2.name, orig.name, sizeof(orig.name));
533 	memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys));
534 	memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq));
535 	ev->u.create2.rd_size = orig.rd_size;
536 	ev->u.create2.bus = orig.bus;
537 	ev->u.create2.vendor = orig.vendor;
538 	ev->u.create2.product = orig.product;
539 	ev->u.create2.version = orig.version;
540 	ev->u.create2.country = orig.country;
541 
542 	return uhid_dev_create2(uhid, ev);
543 }
544 
545 static int uhid_dev_destroy(struct uhid_device *uhid)
546 {
547 	if (!uhid->running)
548 		return -EINVAL;
549 
550 	uhid->running = false;
551 	wake_up_interruptible(&uhid->report_wait);
552 
553 	hid_destroy_device(uhid->hid);
554 	kfree(uhid->rd_data);
555 
556 	return 0;
557 }
558 
559 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
560 {
561 	if (!uhid->running)
562 		return -EINVAL;
563 
564 	hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
565 			 min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
566 
567 	return 0;
568 }
569 
570 static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev)
571 {
572 	if (!uhid->running)
573 		return -EINVAL;
574 
575 	hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data,
576 			 min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), 0);
577 
578 	return 0;
579 }
580 
581 static int uhid_dev_get_report_reply(struct uhid_device *uhid,
582 				     struct uhid_event *ev)
583 {
584 	if (!uhid->running)
585 		return -EINVAL;
586 
587 	uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev);
588 	return 0;
589 }
590 
591 static int uhid_dev_set_report_reply(struct uhid_device *uhid,
592 				     struct uhid_event *ev)
593 {
594 	if (!uhid->running)
595 		return -EINVAL;
596 
597 	uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev);
598 	return 0;
599 }
600 
601 static int uhid_char_open(struct inode *inode, struct file *file)
602 {
603 	struct uhid_device *uhid;
604 
605 	uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
606 	if (!uhid)
607 		return -ENOMEM;
608 
609 	mutex_init(&uhid->devlock);
610 	mutex_init(&uhid->report_lock);
611 	spin_lock_init(&uhid->qlock);
612 	init_waitqueue_head(&uhid->waitq);
613 	init_waitqueue_head(&uhid->report_wait);
614 	uhid->running = false;
615 
616 	file->private_data = uhid;
617 	nonseekable_open(inode, file);
618 
619 	return 0;
620 }
621 
622 static int uhid_char_release(struct inode *inode, struct file *file)
623 {
624 	struct uhid_device *uhid = file->private_data;
625 	unsigned int i;
626 
627 	uhid_dev_destroy(uhid);
628 
629 	for (i = 0; i < UHID_BUFSIZE; ++i)
630 		kfree(uhid->outq[i]);
631 
632 	kfree(uhid);
633 
634 	return 0;
635 }
636 
637 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
638 				size_t count, loff_t *ppos)
639 {
640 	struct uhid_device *uhid = file->private_data;
641 	int ret;
642 	unsigned long flags;
643 	size_t len;
644 
645 	/* they need at least the "type" member of uhid_event */
646 	if (count < sizeof(__u32))
647 		return -EINVAL;
648 
649 try_again:
650 	if (file->f_flags & O_NONBLOCK) {
651 		if (uhid->head == uhid->tail)
652 			return -EAGAIN;
653 	} else {
654 		ret = wait_event_interruptible(uhid->waitq,
655 						uhid->head != uhid->tail);
656 		if (ret)
657 			return ret;
658 	}
659 
660 	ret = mutex_lock_interruptible(&uhid->devlock);
661 	if (ret)
662 		return ret;
663 
664 	if (uhid->head == uhid->tail) {
665 		mutex_unlock(&uhid->devlock);
666 		goto try_again;
667 	} else {
668 		len = min(count, sizeof(**uhid->outq));
669 		if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) {
670 			ret = -EFAULT;
671 		} else {
672 			kfree(uhid->outq[uhid->tail]);
673 			uhid->outq[uhid->tail] = NULL;
674 
675 			spin_lock_irqsave(&uhid->qlock, flags);
676 			uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
677 			spin_unlock_irqrestore(&uhid->qlock, flags);
678 		}
679 	}
680 
681 	mutex_unlock(&uhid->devlock);
682 	return ret ? ret : len;
683 }
684 
685 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
686 				size_t count, loff_t *ppos)
687 {
688 	struct uhid_device *uhid = file->private_data;
689 	int ret;
690 	size_t len;
691 
692 	/* we need at least the "type" member of uhid_event */
693 	if (count < sizeof(__u32))
694 		return -EINVAL;
695 
696 	ret = mutex_lock_interruptible(&uhid->devlock);
697 	if (ret)
698 		return ret;
699 
700 	memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
701 	len = min(count, sizeof(uhid->input_buf));
702 
703 	ret = uhid_event_from_user(buffer, len, &uhid->input_buf);
704 	if (ret)
705 		goto unlock;
706 
707 	switch (uhid->input_buf.type) {
708 	case UHID_CREATE:
709 		ret = uhid_dev_create(uhid, &uhid->input_buf);
710 		break;
711 	case UHID_CREATE2:
712 		ret = uhid_dev_create2(uhid, &uhid->input_buf);
713 		break;
714 	case UHID_DESTROY:
715 		ret = uhid_dev_destroy(uhid);
716 		break;
717 	case UHID_INPUT:
718 		ret = uhid_dev_input(uhid, &uhid->input_buf);
719 		break;
720 	case UHID_INPUT2:
721 		ret = uhid_dev_input2(uhid, &uhid->input_buf);
722 		break;
723 	case UHID_GET_REPORT_REPLY:
724 		ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf);
725 		break;
726 	case UHID_SET_REPORT_REPLY:
727 		ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf);
728 		break;
729 	default:
730 		ret = -EOPNOTSUPP;
731 	}
732 
733 unlock:
734 	mutex_unlock(&uhid->devlock);
735 
736 	/* return "count" not "len" to not confuse the caller */
737 	return ret ? ret : count;
738 }
739 
740 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
741 {
742 	struct uhid_device *uhid = file->private_data;
743 
744 	poll_wait(file, &uhid->waitq, wait);
745 
746 	if (uhid->head != uhid->tail)
747 		return POLLIN | POLLRDNORM;
748 
749 	return 0;
750 }
751 
752 static const struct file_operations uhid_fops = {
753 	.owner		= THIS_MODULE,
754 	.open		= uhid_char_open,
755 	.release	= uhid_char_release,
756 	.read		= uhid_char_read,
757 	.write		= uhid_char_write,
758 	.poll		= uhid_char_poll,
759 	.llseek		= no_llseek,
760 };
761 
762 static struct miscdevice uhid_misc = {
763 	.fops		= &uhid_fops,
764 	.minor		= UHID_MINOR,
765 	.name		= UHID_NAME,
766 };
767 
768 static int __init uhid_init(void)
769 {
770 	return misc_register(&uhid_misc);
771 }
772 
773 static void __exit uhid_exit(void)
774 {
775 	misc_deregister(&uhid_misc);
776 }
777 
778 module_init(uhid_init);
779 module_exit(uhid_exit);
780 MODULE_LICENSE("GPL");
781 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
782 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
783 MODULE_ALIAS_MISCDEV(UHID_MINOR);
784 MODULE_ALIAS("devname:" UHID_NAME);
785