Merge branches 'for-4.8/alps', 'for-4.8/apple', 'for-4.8/i2c-hid', 'for-4.8/uhid...
[sfrench/cifs-2.6.git] / drivers / hid / uhid.c
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 static 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
382 #ifdef CONFIG_COMPAT
383
384 /* Apparently we haven't stepped on these rakes enough times yet. */
385 struct uhid_create_req_compat {
386         __u8 name[128];
387         __u8 phys[64];
388         __u8 uniq[64];
389
390         compat_uptr_t rd_data;
391         __u16 rd_size;
392
393         __u16 bus;
394         __u32 vendor;
395         __u32 product;
396         __u32 version;
397         __u32 country;
398 } __attribute__((__packed__));
399
400 static int uhid_event_from_user(const char __user *buffer, size_t len,
401                                 struct uhid_event *event)
402 {
403         if (in_compat_syscall()) {
404                 u32 type;
405
406                 if (get_user(type, buffer))
407                         return -EFAULT;
408
409                 if (type == UHID_CREATE) {
410                         /*
411                          * This is our messed up request with compat pointer.
412                          * It is largish (more than 256 bytes) so we better
413                          * allocate it from the heap.
414                          */
415                         struct uhid_create_req_compat *compat;
416
417                         compat = kzalloc(sizeof(*compat), GFP_KERNEL);
418                         if (!compat)
419                                 return -ENOMEM;
420
421                         buffer += sizeof(type);
422                         len -= sizeof(type);
423                         if (copy_from_user(compat, buffer,
424                                            min(len, sizeof(*compat)))) {
425                                 kfree(compat);
426                                 return -EFAULT;
427                         }
428
429                         /* Shuffle the data over to proper structure */
430                         event->type = type;
431
432                         memcpy(event->u.create.name, compat->name,
433                                 sizeof(compat->name));
434                         memcpy(event->u.create.phys, compat->phys,
435                                 sizeof(compat->phys));
436                         memcpy(event->u.create.uniq, compat->uniq,
437                                 sizeof(compat->uniq));
438
439                         event->u.create.rd_data = compat_ptr(compat->rd_data);
440                         event->u.create.rd_size = compat->rd_size;
441
442                         event->u.create.bus = compat->bus;
443                         event->u.create.vendor = compat->vendor;
444                         event->u.create.product = compat->product;
445                         event->u.create.version = compat->version;
446                         event->u.create.country = compat->country;
447
448                         kfree(compat);
449                         return 0;
450                 }
451                 /* All others can be copied directly */
452         }
453
454         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
455                 return -EFAULT;
456
457         return 0;
458 }
459 #else
460 static int uhid_event_from_user(const char __user *buffer, size_t len,
461                                 struct uhid_event *event)
462 {
463         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
464                 return -EFAULT;
465
466         return 0;
467 }
468 #endif
469
470 static int uhid_dev_create2(struct uhid_device *uhid,
471                             const struct uhid_event *ev)
472 {
473         struct hid_device *hid;
474         size_t rd_size, len;
475         void *rd_data;
476         int ret;
477
478         if (uhid->running)
479                 return -EALREADY;
480
481         rd_size = ev->u.create2.rd_size;
482         if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE)
483                 return -EINVAL;
484
485         rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL);
486         if (!rd_data)
487                 return -ENOMEM;
488
489         uhid->rd_size = rd_size;
490         uhid->rd_data = rd_data;
491
492         hid = hid_allocate_device();
493         if (IS_ERR(hid)) {
494                 ret = PTR_ERR(hid);
495                 goto err_free;
496         }
497
498         len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1;
499         strncpy(hid->name, ev->u.create2.name, len);
500         len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1;
501         strncpy(hid->phys, ev->u.create2.phys, len);
502         len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1;
503         strncpy(hid->uniq, ev->u.create2.uniq, len);
504
505         hid->ll_driver = &uhid_hid_driver;
506         hid->bus = ev->u.create2.bus;
507         hid->vendor = ev->u.create2.vendor;
508         hid->product = ev->u.create2.product;
509         hid->version = ev->u.create2.version;
510         hid->country = ev->u.create2.country;
511         hid->driver_data = uhid;
512         hid->dev.parent = uhid_misc.this_device;
513
514         uhid->hid = hid;
515         uhid->running = true;
516
517         /* Adding of a HID device is done through a worker, to allow HID drivers
518          * which use feature requests during .probe to work, without they would
519          * be blocked on devlock, which is held by uhid_char_write.
520          */
521         schedule_work(&uhid->worker);
522
523         return 0;
524
525 err_free:
526         kfree(uhid->rd_data);
527         uhid->rd_data = NULL;
528         uhid->rd_size = 0;
529         return ret;
530 }
531
532 static int uhid_dev_create(struct uhid_device *uhid,
533                            struct uhid_event *ev)
534 {
535         struct uhid_create_req orig;
536
537         orig = ev->u.create;
538
539         if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE)
540                 return -EINVAL;
541         if (copy_from_user(&ev->u.create2.rd_data, orig.rd_data, orig.rd_size))
542                 return -EFAULT;
543
544         memcpy(ev->u.create2.name, orig.name, sizeof(orig.name));
545         memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys));
546         memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq));
547         ev->u.create2.rd_size = orig.rd_size;
548         ev->u.create2.bus = orig.bus;
549         ev->u.create2.vendor = orig.vendor;
550         ev->u.create2.product = orig.product;
551         ev->u.create2.version = orig.version;
552         ev->u.create2.country = orig.country;
553
554         return uhid_dev_create2(uhid, ev);
555 }
556
557 static int uhid_dev_destroy(struct uhid_device *uhid)
558 {
559         if (!uhid->running)
560                 return -EINVAL;
561
562         uhid->running = false;
563         wake_up_interruptible(&uhid->report_wait);
564
565         cancel_work_sync(&uhid->worker);
566
567         hid_destroy_device(uhid->hid);
568         kfree(uhid->rd_data);
569
570         return 0;
571 }
572
573 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
574 {
575         if (!uhid->running)
576                 return -EINVAL;
577
578         hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
579                          min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
580
581         return 0;
582 }
583
584 static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev)
585 {
586         if (!uhid->running)
587                 return -EINVAL;
588
589         hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data,
590                          min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), 0);
591
592         return 0;
593 }
594
595 static int uhid_dev_get_report_reply(struct uhid_device *uhid,
596                                      struct uhid_event *ev)
597 {
598         if (!uhid->running)
599                 return -EINVAL;
600
601         uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev);
602         return 0;
603 }
604
605 static int uhid_dev_set_report_reply(struct uhid_device *uhid,
606                                      struct uhid_event *ev)
607 {
608         if (!uhid->running)
609                 return -EINVAL;
610
611         uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev);
612         return 0;
613 }
614
615 static int uhid_char_open(struct inode *inode, struct file *file)
616 {
617         struct uhid_device *uhid;
618
619         uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
620         if (!uhid)
621                 return -ENOMEM;
622
623         mutex_init(&uhid->devlock);
624         mutex_init(&uhid->report_lock);
625         spin_lock_init(&uhid->qlock);
626         init_waitqueue_head(&uhid->waitq);
627         init_waitqueue_head(&uhid->report_wait);
628         uhid->running = false;
629         INIT_WORK(&uhid->worker, uhid_device_add_worker);
630
631         file->private_data = uhid;
632         nonseekable_open(inode, file);
633
634         return 0;
635 }
636
637 static int uhid_char_release(struct inode *inode, struct file *file)
638 {
639         struct uhid_device *uhid = file->private_data;
640         unsigned int i;
641
642         uhid_dev_destroy(uhid);
643
644         for (i = 0; i < UHID_BUFSIZE; ++i)
645                 kfree(uhid->outq[i]);
646
647         kfree(uhid);
648
649         return 0;
650 }
651
652 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
653                                 size_t count, loff_t *ppos)
654 {
655         struct uhid_device *uhid = file->private_data;
656         int ret;
657         unsigned long flags;
658         size_t len;
659
660         /* they need at least the "type" member of uhid_event */
661         if (count < sizeof(__u32))
662                 return -EINVAL;
663
664 try_again:
665         if (file->f_flags & O_NONBLOCK) {
666                 if (uhid->head == uhid->tail)
667                         return -EAGAIN;
668         } else {
669                 ret = wait_event_interruptible(uhid->waitq,
670                                                 uhid->head != uhid->tail);
671                 if (ret)
672                         return ret;
673         }
674
675         ret = mutex_lock_interruptible(&uhid->devlock);
676         if (ret)
677                 return ret;
678
679         if (uhid->head == uhid->tail) {
680                 mutex_unlock(&uhid->devlock);
681                 goto try_again;
682         } else {
683                 len = min(count, sizeof(**uhid->outq));
684                 if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) {
685                         ret = -EFAULT;
686                 } else {
687                         kfree(uhid->outq[uhid->tail]);
688                         uhid->outq[uhid->tail] = NULL;
689
690                         spin_lock_irqsave(&uhid->qlock, flags);
691                         uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
692                         spin_unlock_irqrestore(&uhid->qlock, flags);
693                 }
694         }
695
696         mutex_unlock(&uhid->devlock);
697         return ret ? ret : len;
698 }
699
700 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
701                                 size_t count, loff_t *ppos)
702 {
703         struct uhid_device *uhid = file->private_data;
704         int ret;
705         size_t len;
706
707         /* we need at least the "type" member of uhid_event */
708         if (count < sizeof(__u32))
709                 return -EINVAL;
710
711         ret = mutex_lock_interruptible(&uhid->devlock);
712         if (ret)
713                 return ret;
714
715         memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
716         len = min(count, sizeof(uhid->input_buf));
717
718         ret = uhid_event_from_user(buffer, len, &uhid->input_buf);
719         if (ret)
720                 goto unlock;
721
722         switch (uhid->input_buf.type) {
723         case UHID_CREATE:
724                 ret = uhid_dev_create(uhid, &uhid->input_buf);
725                 break;
726         case UHID_CREATE2:
727                 ret = uhid_dev_create2(uhid, &uhid->input_buf);
728                 break;
729         case UHID_DESTROY:
730                 ret = uhid_dev_destroy(uhid);
731                 break;
732         case UHID_INPUT:
733                 ret = uhid_dev_input(uhid, &uhid->input_buf);
734                 break;
735         case UHID_INPUT2:
736                 ret = uhid_dev_input2(uhid, &uhid->input_buf);
737                 break;
738         case UHID_GET_REPORT_REPLY:
739                 ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf);
740                 break;
741         case UHID_SET_REPORT_REPLY:
742                 ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf);
743                 break;
744         default:
745                 ret = -EOPNOTSUPP;
746         }
747
748 unlock:
749         mutex_unlock(&uhid->devlock);
750
751         /* return "count" not "len" to not confuse the caller */
752         return ret ? ret : count;
753 }
754
755 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
756 {
757         struct uhid_device *uhid = file->private_data;
758
759         poll_wait(file, &uhid->waitq, wait);
760
761         if (uhid->head != uhid->tail)
762                 return POLLIN | POLLRDNORM;
763
764         return 0;
765 }
766
767 static const struct file_operations uhid_fops = {
768         .owner          = THIS_MODULE,
769         .open           = uhid_char_open,
770         .release        = uhid_char_release,
771         .read           = uhid_char_read,
772         .write          = uhid_char_write,
773         .poll           = uhid_char_poll,
774         .llseek         = no_llseek,
775 };
776
777 static struct miscdevice uhid_misc = {
778         .fops           = &uhid_fops,
779         .minor          = UHID_MINOR,
780         .name           = UHID_NAME,
781 };
782
783 static int __init uhid_init(void)
784 {
785         return misc_register(&uhid_misc);
786 }
787
788 static void __exit uhid_exit(void)
789 {
790         misc_deregister(&uhid_misc);
791 }
792
793 module_init(uhid_init);
794 module_exit(uhid_exit);
795 MODULE_LICENSE("GPL");
796 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
797 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
798 MODULE_ALIAS_MISCDEV(UHID_MINOR);
799 MODULE_ALIAS("devname:" UHID_NAME);