xref: /openbmc/linux/drivers/hid/uhid.c (revision 7211ec63)
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 	struct work_struct worker;
55 };
56 
57 static struct miscdevice uhid_misc;
58 
59 static void uhid_device_add_worker(struct work_struct *work)
60 {
61 	struct uhid_device *uhid = container_of(work, struct uhid_device, worker);
62 	int ret;
63 
64 	ret = hid_add_device(uhid->hid);
65 	if (ret) {
66 		hid_err(uhid->hid, "Cannot register HID device: error %d\n", ret);
67 
68 		hid_destroy_device(uhid->hid);
69 		uhid->hid = NULL;
70 		uhid->running = false;
71 	}
72 }
73 
74 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
75 {
76 	__u8 newhead;
77 
78 	newhead = (uhid->head + 1) % UHID_BUFSIZE;
79 
80 	if (newhead != uhid->tail) {
81 		uhid->outq[uhid->head] = ev;
82 		uhid->head = newhead;
83 		wake_up_interruptible(&uhid->waitq);
84 	} else {
85 		hid_warn(uhid->hid, "Output queue is full\n");
86 		kfree(ev);
87 	}
88 }
89 
90 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
91 {
92 	unsigned long flags;
93 	struct uhid_event *ev;
94 
95 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
96 	if (!ev)
97 		return -ENOMEM;
98 
99 	ev->type = event;
100 
101 	spin_lock_irqsave(&uhid->qlock, flags);
102 	uhid_queue(uhid, ev);
103 	spin_unlock_irqrestore(&uhid->qlock, flags);
104 
105 	return 0;
106 }
107 
108 static int uhid_hid_start(struct hid_device *hid)
109 {
110 	struct uhid_device *uhid = hid->driver_data;
111 	struct uhid_event *ev;
112 	unsigned long flags;
113 
114 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
115 	if (!ev)
116 		return -ENOMEM;
117 
118 	ev->type = UHID_START;
119 
120 	if (hid->report_enum[HID_FEATURE_REPORT].numbered)
121 		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS;
122 	if (hid->report_enum[HID_OUTPUT_REPORT].numbered)
123 		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS;
124 	if (hid->report_enum[HID_INPUT_REPORT].numbered)
125 		ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS;
126 
127 	spin_lock_irqsave(&uhid->qlock, flags);
128 	uhid_queue(uhid, ev);
129 	spin_unlock_irqrestore(&uhid->qlock, flags);
130 
131 	return 0;
132 }
133 
134 static void uhid_hid_stop(struct hid_device *hid)
135 {
136 	struct uhid_device *uhid = hid->driver_data;
137 
138 	hid->claimed = 0;
139 	uhid_queue_event(uhid, UHID_STOP);
140 }
141 
142 static int uhid_hid_open(struct hid_device *hid)
143 {
144 	struct uhid_device *uhid = hid->driver_data;
145 
146 	return uhid_queue_event(uhid, UHID_OPEN);
147 }
148 
149 static void uhid_hid_close(struct hid_device *hid)
150 {
151 	struct uhid_device *uhid = hid->driver_data;
152 
153 	uhid_queue_event(uhid, UHID_CLOSE);
154 }
155 
156 static int uhid_hid_parse(struct hid_device *hid)
157 {
158 	struct uhid_device *uhid = hid->driver_data;
159 
160 	return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
161 }
162 
163 /* must be called with report_lock held */
164 static int __uhid_report_queue_and_wait(struct uhid_device *uhid,
165 					struct uhid_event *ev,
166 					__u32 *report_id)
167 {
168 	unsigned long flags;
169 	int ret;
170 
171 	spin_lock_irqsave(&uhid->qlock, flags);
172 	*report_id = ++uhid->report_id;
173 	uhid->report_type = ev->type + 1;
174 	uhid->report_running = true;
175 	uhid_queue(uhid, ev);
176 	spin_unlock_irqrestore(&uhid->qlock, flags);
177 
178 	ret = wait_event_interruptible_timeout(uhid->report_wait,
179 				!uhid->report_running || !uhid->running,
180 				5 * HZ);
181 	if (!ret || !uhid->running || uhid->report_running)
182 		ret = -EIO;
183 	else if (ret < 0)
184 		ret = -ERESTARTSYS;
185 	else
186 		ret = 0;
187 
188 	uhid->report_running = false;
189 
190 	return ret;
191 }
192 
193 static void uhid_report_wake_up(struct uhid_device *uhid, u32 id,
194 				const struct uhid_event *ev)
195 {
196 	unsigned long flags;
197 
198 	spin_lock_irqsave(&uhid->qlock, flags);
199 
200 	/* id for old report; drop it silently */
201 	if (uhid->report_type != ev->type || uhid->report_id != id)
202 		goto unlock;
203 	if (!uhid->report_running)
204 		goto unlock;
205 
206 	memcpy(&uhid->report_buf, ev, sizeof(*ev));
207 	uhid->report_running = false;
208 	wake_up_interruptible(&uhid->report_wait);
209 
210 unlock:
211 	spin_unlock_irqrestore(&uhid->qlock, flags);
212 }
213 
214 static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum,
215 			       u8 *buf, size_t count, u8 rtype)
216 {
217 	struct uhid_device *uhid = hid->driver_data;
218 	struct uhid_get_report_reply_req *req;
219 	struct uhid_event *ev;
220 	int ret;
221 
222 	if (!uhid->running)
223 		return -EIO;
224 
225 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
226 	if (!ev)
227 		return -ENOMEM;
228 
229 	ev->type = UHID_GET_REPORT;
230 	ev->u.get_report.rnum = rnum;
231 	ev->u.get_report.rtype = rtype;
232 
233 	ret = mutex_lock_interruptible(&uhid->report_lock);
234 	if (ret) {
235 		kfree(ev);
236 		return ret;
237 	}
238 
239 	/* this _always_ takes ownership of @ev */
240 	ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.get_report.id);
241 	if (ret)
242 		goto unlock;
243 
244 	req = &uhid->report_buf.u.get_report_reply;
245 	if (req->err) {
246 		ret = -EIO;
247 	} else {
248 		ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX);
249 		memcpy(buf, req->data, ret);
250 	}
251 
252 unlock:
253 	mutex_unlock(&uhid->report_lock);
254 	return ret;
255 }
256 
257 static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum,
258 			       const u8 *buf, size_t count, u8 rtype)
259 {
260 	struct uhid_device *uhid = hid->driver_data;
261 	struct uhid_event *ev;
262 	int ret;
263 
264 	if (!uhid->running || count > UHID_DATA_MAX)
265 		return -EIO;
266 
267 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
268 	if (!ev)
269 		return -ENOMEM;
270 
271 	ev->type = UHID_SET_REPORT;
272 	ev->u.set_report.rnum = rnum;
273 	ev->u.set_report.rtype = rtype;
274 	ev->u.set_report.size = count;
275 	memcpy(ev->u.set_report.data, buf, count);
276 
277 	ret = mutex_lock_interruptible(&uhid->report_lock);
278 	if (ret) {
279 		kfree(ev);
280 		return ret;
281 	}
282 
283 	/* this _always_ takes ownership of @ev */
284 	ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.set_report.id);
285 	if (ret)
286 		goto unlock;
287 
288 	if (uhid->report_buf.u.set_report_reply.err)
289 		ret = -EIO;
290 	else
291 		ret = count;
292 
293 unlock:
294 	mutex_unlock(&uhid->report_lock);
295 	return ret;
296 }
297 
298 static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum,
299 				__u8 *buf, size_t len, unsigned char rtype,
300 				int reqtype)
301 {
302 	u8 u_rtype;
303 
304 	switch (rtype) {
305 	case HID_FEATURE_REPORT:
306 		u_rtype = UHID_FEATURE_REPORT;
307 		break;
308 	case HID_OUTPUT_REPORT:
309 		u_rtype = UHID_OUTPUT_REPORT;
310 		break;
311 	case HID_INPUT_REPORT:
312 		u_rtype = UHID_INPUT_REPORT;
313 		break;
314 	default:
315 		return -EINVAL;
316 	}
317 
318 	switch (reqtype) {
319 	case HID_REQ_GET_REPORT:
320 		return uhid_hid_get_report(hid, reportnum, buf, len, u_rtype);
321 	case HID_REQ_SET_REPORT:
322 		return uhid_hid_set_report(hid, reportnum, buf, len, u_rtype);
323 	default:
324 		return -EIO;
325 	}
326 }
327 
328 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
329 			       unsigned char report_type)
330 {
331 	struct uhid_device *uhid = hid->driver_data;
332 	__u8 rtype;
333 	unsigned long flags;
334 	struct uhid_event *ev;
335 
336 	switch (report_type) {
337 	case HID_FEATURE_REPORT:
338 		rtype = UHID_FEATURE_REPORT;
339 		break;
340 	case HID_OUTPUT_REPORT:
341 		rtype = UHID_OUTPUT_REPORT;
342 		break;
343 	default:
344 		return -EINVAL;
345 	}
346 
347 	if (count < 1 || count > UHID_DATA_MAX)
348 		return -EINVAL;
349 
350 	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
351 	if (!ev)
352 		return -ENOMEM;
353 
354 	ev->type = UHID_OUTPUT;
355 	ev->u.output.size = count;
356 	ev->u.output.rtype = rtype;
357 	memcpy(ev->u.output.data, buf, count);
358 
359 	spin_lock_irqsave(&uhid->qlock, flags);
360 	uhid_queue(uhid, ev);
361 	spin_unlock_irqrestore(&uhid->qlock, flags);
362 
363 	return count;
364 }
365 
366 static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf,
367 				  size_t count)
368 {
369 	return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT);
370 }
371 
372 struct hid_ll_driver uhid_hid_driver = {
373 	.start = uhid_hid_start,
374 	.stop = uhid_hid_stop,
375 	.open = uhid_hid_open,
376 	.close = uhid_hid_close,
377 	.parse = uhid_hid_parse,
378 	.raw_request = uhid_hid_raw_request,
379 	.output_report = uhid_hid_output_report,
380 };
381 EXPORT_SYMBOL_GPL(uhid_hid_driver);
382 
383 #ifdef CONFIG_COMPAT
384 
385 /* Apparently we haven't stepped on these rakes enough times yet. */
386 struct uhid_create_req_compat {
387 	__u8 name[128];
388 	__u8 phys[64];
389 	__u8 uniq[64];
390 
391 	compat_uptr_t rd_data;
392 	__u16 rd_size;
393 
394 	__u16 bus;
395 	__u32 vendor;
396 	__u32 product;
397 	__u32 version;
398 	__u32 country;
399 } __attribute__((__packed__));
400 
401 static int uhid_event_from_user(const char __user *buffer, size_t len,
402 				struct uhid_event *event)
403 {
404 	if (in_compat_syscall()) {
405 		u32 type;
406 
407 		if (get_user(type, buffer))
408 			return -EFAULT;
409 
410 		if (type == UHID_CREATE) {
411 			/*
412 			 * This is our messed up request with compat pointer.
413 			 * It is largish (more than 256 bytes) so we better
414 			 * allocate it from the heap.
415 			 */
416 			struct uhid_create_req_compat *compat;
417 
418 			compat = kzalloc(sizeof(*compat), GFP_KERNEL);
419 			if (!compat)
420 				return -ENOMEM;
421 
422 			buffer += sizeof(type);
423 			len -= sizeof(type);
424 			if (copy_from_user(compat, buffer,
425 					   min(len, sizeof(*compat)))) {
426 				kfree(compat);
427 				return -EFAULT;
428 			}
429 
430 			/* Shuffle the data over to proper structure */
431 			event->type = type;
432 
433 			memcpy(event->u.create.name, compat->name,
434 				sizeof(compat->name));
435 			memcpy(event->u.create.phys, compat->phys,
436 				sizeof(compat->phys));
437 			memcpy(event->u.create.uniq, compat->uniq,
438 				sizeof(compat->uniq));
439 
440 			event->u.create.rd_data = compat_ptr(compat->rd_data);
441 			event->u.create.rd_size = compat->rd_size;
442 
443 			event->u.create.bus = compat->bus;
444 			event->u.create.vendor = compat->vendor;
445 			event->u.create.product = compat->product;
446 			event->u.create.version = compat->version;
447 			event->u.create.country = compat->country;
448 
449 			kfree(compat);
450 			return 0;
451 		}
452 		/* All others can be copied directly */
453 	}
454 
455 	if (copy_from_user(event, buffer, min(len, sizeof(*event))))
456 		return -EFAULT;
457 
458 	return 0;
459 }
460 #else
461 static int uhid_event_from_user(const char __user *buffer, size_t len,
462 				struct uhid_event *event)
463 {
464 	if (copy_from_user(event, buffer, min(len, sizeof(*event))))
465 		return -EFAULT;
466 
467 	return 0;
468 }
469 #endif
470 
471 static int uhid_dev_create2(struct uhid_device *uhid,
472 			    const struct uhid_event *ev)
473 {
474 	struct hid_device *hid;
475 	size_t rd_size, len;
476 	void *rd_data;
477 	int ret;
478 
479 	if (uhid->running)
480 		return -EALREADY;
481 
482 	rd_size = ev->u.create2.rd_size;
483 	if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE)
484 		return -EINVAL;
485 
486 	rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL);
487 	if (!rd_data)
488 		return -ENOMEM;
489 
490 	uhid->rd_size = rd_size;
491 	uhid->rd_data = rd_data;
492 
493 	hid = hid_allocate_device();
494 	if (IS_ERR(hid)) {
495 		ret = PTR_ERR(hid);
496 		goto err_free;
497 	}
498 
499 	len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1;
500 	strncpy(hid->name, ev->u.create2.name, len);
501 	len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1;
502 	strncpy(hid->phys, ev->u.create2.phys, len);
503 	len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1;
504 	strncpy(hid->uniq, ev->u.create2.uniq, len);
505 
506 	hid->ll_driver = &uhid_hid_driver;
507 	hid->bus = ev->u.create2.bus;
508 	hid->vendor = ev->u.create2.vendor;
509 	hid->product = ev->u.create2.product;
510 	hid->version = ev->u.create2.version;
511 	hid->country = ev->u.create2.country;
512 	hid->driver_data = uhid;
513 	hid->dev.parent = uhid_misc.this_device;
514 
515 	uhid->hid = hid;
516 	uhid->running = true;
517 
518 	/* Adding of a HID device is done through a worker, to allow HID drivers
519 	 * which use feature requests during .probe to work, without they would
520 	 * be blocked on devlock, which is held by uhid_char_write.
521 	 */
522 	schedule_work(&uhid->worker);
523 
524 	return 0;
525 
526 err_free:
527 	kfree(uhid->rd_data);
528 	uhid->rd_data = NULL;
529 	uhid->rd_size = 0;
530 	return ret;
531 }
532 
533 static int uhid_dev_create(struct uhid_device *uhid,
534 			   struct uhid_event *ev)
535 {
536 	struct uhid_create_req orig;
537 
538 	orig = ev->u.create;
539 
540 	if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE)
541 		return -EINVAL;
542 	if (copy_from_user(&ev->u.create2.rd_data, orig.rd_data, orig.rd_size))
543 		return -EFAULT;
544 
545 	memcpy(ev->u.create2.name, orig.name, sizeof(orig.name));
546 	memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys));
547 	memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq));
548 	ev->u.create2.rd_size = orig.rd_size;
549 	ev->u.create2.bus = orig.bus;
550 	ev->u.create2.vendor = orig.vendor;
551 	ev->u.create2.product = orig.product;
552 	ev->u.create2.version = orig.version;
553 	ev->u.create2.country = orig.country;
554 
555 	return uhid_dev_create2(uhid, ev);
556 }
557 
558 static int uhid_dev_destroy(struct uhid_device *uhid)
559 {
560 	if (!uhid->running)
561 		return -EINVAL;
562 
563 	uhid->running = false;
564 	wake_up_interruptible(&uhid->report_wait);
565 
566 	cancel_work_sync(&uhid->worker);
567 
568 	hid_destroy_device(uhid->hid);
569 	kfree(uhid->rd_data);
570 
571 	return 0;
572 }
573 
574 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
575 {
576 	if (!uhid->running)
577 		return -EINVAL;
578 
579 	hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
580 			 min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
581 
582 	return 0;
583 }
584 
585 static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev)
586 {
587 	if (!uhid->running)
588 		return -EINVAL;
589 
590 	hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data,
591 			 min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), 0);
592 
593 	return 0;
594 }
595 
596 static int uhid_dev_get_report_reply(struct uhid_device *uhid,
597 				     struct uhid_event *ev)
598 {
599 	if (!uhid->running)
600 		return -EINVAL;
601 
602 	uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev);
603 	return 0;
604 }
605 
606 static int uhid_dev_set_report_reply(struct uhid_device *uhid,
607 				     struct uhid_event *ev)
608 {
609 	if (!uhid->running)
610 		return -EINVAL;
611 
612 	uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev);
613 	return 0;
614 }
615 
616 static int uhid_char_open(struct inode *inode, struct file *file)
617 {
618 	struct uhid_device *uhid;
619 
620 	uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
621 	if (!uhid)
622 		return -ENOMEM;
623 
624 	mutex_init(&uhid->devlock);
625 	mutex_init(&uhid->report_lock);
626 	spin_lock_init(&uhid->qlock);
627 	init_waitqueue_head(&uhid->waitq);
628 	init_waitqueue_head(&uhid->report_wait);
629 	uhid->running = false;
630 	INIT_WORK(&uhid->worker, uhid_device_add_worker);
631 
632 	file->private_data = uhid;
633 	nonseekable_open(inode, file);
634 
635 	return 0;
636 }
637 
638 static int uhid_char_release(struct inode *inode, struct file *file)
639 {
640 	struct uhid_device *uhid = file->private_data;
641 	unsigned int i;
642 
643 	uhid_dev_destroy(uhid);
644 
645 	for (i = 0; i < UHID_BUFSIZE; ++i)
646 		kfree(uhid->outq[i]);
647 
648 	kfree(uhid);
649 
650 	return 0;
651 }
652 
653 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
654 				size_t count, loff_t *ppos)
655 {
656 	struct uhid_device *uhid = file->private_data;
657 	int ret;
658 	unsigned long flags;
659 	size_t len;
660 
661 	/* they need at least the "type" member of uhid_event */
662 	if (count < sizeof(__u32))
663 		return -EINVAL;
664 
665 try_again:
666 	if (file->f_flags & O_NONBLOCK) {
667 		if (uhid->head == uhid->tail)
668 			return -EAGAIN;
669 	} else {
670 		ret = wait_event_interruptible(uhid->waitq,
671 						uhid->head != uhid->tail);
672 		if (ret)
673 			return ret;
674 	}
675 
676 	ret = mutex_lock_interruptible(&uhid->devlock);
677 	if (ret)
678 		return ret;
679 
680 	if (uhid->head == uhid->tail) {
681 		mutex_unlock(&uhid->devlock);
682 		goto try_again;
683 	} else {
684 		len = min(count, sizeof(**uhid->outq));
685 		if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) {
686 			ret = -EFAULT;
687 		} else {
688 			kfree(uhid->outq[uhid->tail]);
689 			uhid->outq[uhid->tail] = NULL;
690 
691 			spin_lock_irqsave(&uhid->qlock, flags);
692 			uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
693 			spin_unlock_irqrestore(&uhid->qlock, flags);
694 		}
695 	}
696 
697 	mutex_unlock(&uhid->devlock);
698 	return ret ? ret : len;
699 }
700 
701 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
702 				size_t count, loff_t *ppos)
703 {
704 	struct uhid_device *uhid = file->private_data;
705 	int ret;
706 	size_t len;
707 
708 	/* we need at least the "type" member of uhid_event */
709 	if (count < sizeof(__u32))
710 		return -EINVAL;
711 
712 	ret = mutex_lock_interruptible(&uhid->devlock);
713 	if (ret)
714 		return ret;
715 
716 	memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
717 	len = min(count, sizeof(uhid->input_buf));
718 
719 	ret = uhid_event_from_user(buffer, len, &uhid->input_buf);
720 	if (ret)
721 		goto unlock;
722 
723 	switch (uhid->input_buf.type) {
724 	case UHID_CREATE:
725 		ret = uhid_dev_create(uhid, &uhid->input_buf);
726 		break;
727 	case UHID_CREATE2:
728 		ret = uhid_dev_create2(uhid, &uhid->input_buf);
729 		break;
730 	case UHID_DESTROY:
731 		ret = uhid_dev_destroy(uhid);
732 		break;
733 	case UHID_INPUT:
734 		ret = uhid_dev_input(uhid, &uhid->input_buf);
735 		break;
736 	case UHID_INPUT2:
737 		ret = uhid_dev_input2(uhid, &uhid->input_buf);
738 		break;
739 	case UHID_GET_REPORT_REPLY:
740 		ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf);
741 		break;
742 	case UHID_SET_REPORT_REPLY:
743 		ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf);
744 		break;
745 	default:
746 		ret = -EOPNOTSUPP;
747 	}
748 
749 unlock:
750 	mutex_unlock(&uhid->devlock);
751 
752 	/* return "count" not "len" to not confuse the caller */
753 	return ret ? ret : count;
754 }
755 
756 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
757 {
758 	struct uhid_device *uhid = file->private_data;
759 
760 	poll_wait(file, &uhid->waitq, wait);
761 
762 	if (uhid->head != uhid->tail)
763 		return POLLIN | POLLRDNORM;
764 
765 	return 0;
766 }
767 
768 static const struct file_operations uhid_fops = {
769 	.owner		= THIS_MODULE,
770 	.open		= uhid_char_open,
771 	.release	= uhid_char_release,
772 	.read		= uhid_char_read,
773 	.write		= uhid_char_write,
774 	.poll		= uhid_char_poll,
775 	.llseek		= no_llseek,
776 };
777 
778 static struct miscdevice uhid_misc = {
779 	.fops		= &uhid_fops,
780 	.minor		= UHID_MINOR,
781 	.name		= UHID_NAME,
782 };
783 module_misc_device(uhid_misc);
784 
785 MODULE_LICENSE("GPL");
786 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
787 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
788 MODULE_ALIAS_MISCDEV(UHID_MINOR);
789 MODULE_ALIAS("devname:" UHID_NAME);
790