HID: uhid: forward output request to user-space
[linux-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/device.h>
15 #include <linux/fs.h>
16 #include <linux/hid.h>
17 #include <linux/input.h>
18 #include <linux/miscdevice.h>
19 #include <linux/module.h>
20 #include <linux/mutex.h>
21 #include <linux/poll.h>
22 #include <linux/sched.h>
23 #include <linux/spinlock.h>
24 #include <linux/uhid.h>
25 #include <linux/wait.h>
26
27 #define UHID_NAME       "uhid"
28 #define UHID_BUFSIZE    32
29
30 struct uhid_device {
31         struct mutex devlock;
32         bool running;
33
34         __u8 *rd_data;
35         uint rd_size;
36
37         struct hid_device *hid;
38         struct uhid_event input_buf;
39
40         wait_queue_head_t waitq;
41         spinlock_t qlock;
42         __u8 head;
43         __u8 tail;
44         struct uhid_event *outq[UHID_BUFSIZE];
45 };
46
47 static struct miscdevice uhid_misc;
48
49 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
50 {
51         __u8 newhead;
52
53         newhead = (uhid->head + 1) % UHID_BUFSIZE;
54
55         if (newhead != uhid->tail) {
56                 uhid->outq[uhid->head] = ev;
57                 uhid->head = newhead;
58                 wake_up_interruptible(&uhid->waitq);
59         } else {
60                 hid_warn(uhid->hid, "Output queue is full\n");
61                 kfree(ev);
62         }
63 }
64
65 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
66 {
67         unsigned long flags;
68         struct uhid_event *ev;
69
70         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
71         if (!ev)
72                 return -ENOMEM;
73
74         ev->type = event;
75
76         spin_lock_irqsave(&uhid->qlock, flags);
77         uhid_queue(uhid, ev);
78         spin_unlock_irqrestore(&uhid->qlock, flags);
79
80         return 0;
81 }
82
83 static int uhid_hid_start(struct hid_device *hid)
84 {
85         struct uhid_device *uhid = hid->driver_data;
86
87         return uhid_queue_event(uhid, UHID_START);
88 }
89
90 static void uhid_hid_stop(struct hid_device *hid)
91 {
92         struct uhid_device *uhid = hid->driver_data;
93
94         hid->claimed = 0;
95         uhid_queue_event(uhid, UHID_STOP);
96 }
97
98 static int uhid_hid_open(struct hid_device *hid)
99 {
100         struct uhid_device *uhid = hid->driver_data;
101
102         return uhid_queue_event(uhid, UHID_OPEN);
103 }
104
105 static void uhid_hid_close(struct hid_device *hid)
106 {
107         struct uhid_device *uhid = hid->driver_data;
108
109         uhid_queue_event(uhid, UHID_CLOSE);
110 }
111
112 static int uhid_hid_input(struct input_dev *input, unsigned int type,
113                           unsigned int code, int value)
114 {
115         struct hid_device *hid = input_get_drvdata(input);
116         struct uhid_device *uhid = hid->driver_data;
117         unsigned long flags;
118         struct uhid_event *ev;
119
120         ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
121         if (!ev)
122                 return -ENOMEM;
123
124         ev->type = UHID_OUTPUT_EV;
125         ev->u.output_ev.type = type;
126         ev->u.output_ev.code = code;
127         ev->u.output_ev.value = value;
128
129         spin_lock_irqsave(&uhid->qlock, flags);
130         uhid_queue(uhid, ev);
131         spin_unlock_irqrestore(&uhid->qlock, flags);
132
133         return 0;
134 }
135
136 static int uhid_hid_parse(struct hid_device *hid)
137 {
138         struct uhid_device *uhid = hid->driver_data;
139
140         return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
141 }
142
143 static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
144                             __u8 *buf, size_t count, unsigned char rtype)
145 {
146         return 0;
147 }
148
149 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
150                                unsigned char report_type)
151 {
152         return 0;
153 }
154
155 static struct hid_ll_driver uhid_hid_driver = {
156         .start = uhid_hid_start,
157         .stop = uhid_hid_stop,
158         .open = uhid_hid_open,
159         .close = uhid_hid_close,
160         .hidinput_input_event = uhid_hid_input,
161         .parse = uhid_hid_parse,
162 };
163
164 static int uhid_dev_create(struct uhid_device *uhid,
165                            const struct uhid_event *ev)
166 {
167         struct hid_device *hid;
168         int ret;
169
170         if (uhid->running)
171                 return -EALREADY;
172
173         uhid->rd_size = ev->u.create.rd_size;
174         if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
175                 return -EINVAL;
176
177         uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
178         if (!uhid->rd_data)
179                 return -ENOMEM;
180
181         if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
182                            uhid->rd_size)) {
183                 ret = -EFAULT;
184                 goto err_free;
185         }
186
187         hid = hid_allocate_device();
188         if (IS_ERR(hid)) {
189                 ret = PTR_ERR(hid);
190                 goto err_free;
191         }
192
193         strncpy(hid->name, ev->u.create.name, 127);
194         hid->name[127] = 0;
195         strncpy(hid->phys, ev->u.create.phys, 63);
196         hid->phys[63] = 0;
197         strncpy(hid->uniq, ev->u.create.uniq, 63);
198         hid->uniq[63] = 0;
199
200         hid->ll_driver = &uhid_hid_driver;
201         hid->hid_get_raw_report = uhid_hid_get_raw;
202         hid->hid_output_raw_report = uhid_hid_output_raw;
203         hid->bus = ev->u.create.bus;
204         hid->vendor = ev->u.create.vendor;
205         hid->product = ev->u.create.product;
206         hid->version = ev->u.create.version;
207         hid->country = ev->u.create.country;
208         hid->driver_data = uhid;
209         hid->dev.parent = uhid_misc.this_device;
210
211         uhid->hid = hid;
212         uhid->running = true;
213
214         ret = hid_add_device(hid);
215         if (ret) {
216                 hid_err(hid, "Cannot register HID device\n");
217                 goto err_hid;
218         }
219
220         return 0;
221
222 err_hid:
223         hid_destroy_device(hid);
224         uhid->hid = NULL;
225         uhid->running = false;
226 err_free:
227         kfree(uhid->rd_data);
228         return ret;
229 }
230
231 static int uhid_dev_destroy(struct uhid_device *uhid)
232 {
233         if (!uhid->running)
234                 return -EINVAL;
235
236         uhid->running = false;
237
238         hid_destroy_device(uhid->hid);
239         kfree(uhid->rd_data);
240
241         return 0;
242 }
243
244 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
245 {
246         if (!uhid->running)
247                 return -EINVAL;
248
249         hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
250                          min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
251
252         return 0;
253 }
254
255 static int uhid_char_open(struct inode *inode, struct file *file)
256 {
257         struct uhid_device *uhid;
258
259         uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
260         if (!uhid)
261                 return -ENOMEM;
262
263         mutex_init(&uhid->devlock);
264         spin_lock_init(&uhid->qlock);
265         init_waitqueue_head(&uhid->waitq);
266         uhid->running = false;
267
268         file->private_data = uhid;
269         nonseekable_open(inode, file);
270
271         return 0;
272 }
273
274 static int uhid_char_release(struct inode *inode, struct file *file)
275 {
276         struct uhid_device *uhid = file->private_data;
277         unsigned int i;
278
279         uhid_dev_destroy(uhid);
280
281         for (i = 0; i < UHID_BUFSIZE; ++i)
282                 kfree(uhid->outq[i]);
283
284         kfree(uhid);
285
286         return 0;
287 }
288
289 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
290                                 size_t count, loff_t *ppos)
291 {
292         struct uhid_device *uhid = file->private_data;
293         int ret;
294         unsigned long flags;
295         size_t len;
296
297         /* they need at least the "type" member of uhid_event */
298         if (count < sizeof(__u32))
299                 return -EINVAL;
300
301 try_again:
302         if (file->f_flags & O_NONBLOCK) {
303                 if (uhid->head == uhid->tail)
304                         return -EAGAIN;
305         } else {
306                 ret = wait_event_interruptible(uhid->waitq,
307                                                 uhid->head != uhid->tail);
308                 if (ret)
309                         return ret;
310         }
311
312         ret = mutex_lock_interruptible(&uhid->devlock);
313         if (ret)
314                 return ret;
315
316         if (uhid->head == uhid->tail) {
317                 mutex_unlock(&uhid->devlock);
318                 goto try_again;
319         } else {
320                 len = min(count, sizeof(**uhid->outq));
321                 if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) {
322                         ret = -EFAULT;
323                 } else {
324                         kfree(uhid->outq[uhid->tail]);
325                         uhid->outq[uhid->tail] = NULL;
326
327                         spin_lock_irqsave(&uhid->qlock, flags);
328                         uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
329                         spin_unlock_irqrestore(&uhid->qlock, flags);
330                 }
331         }
332
333         mutex_unlock(&uhid->devlock);
334         return ret ? ret : len;
335 }
336
337 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
338                                 size_t count, loff_t *ppos)
339 {
340         struct uhid_device *uhid = file->private_data;
341         int ret;
342         size_t len;
343
344         /* we need at least the "type" member of uhid_event */
345         if (count < sizeof(__u32))
346                 return -EINVAL;
347
348         ret = mutex_lock_interruptible(&uhid->devlock);
349         if (ret)
350                 return ret;
351
352         memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
353         len = min(count, sizeof(uhid->input_buf));
354         if (copy_from_user(&uhid->input_buf, buffer, len)) {
355                 ret = -EFAULT;
356                 goto unlock;
357         }
358
359         switch (uhid->input_buf.type) {
360         case UHID_CREATE:
361                 ret = uhid_dev_create(uhid, &uhid->input_buf);
362                 break;
363         case UHID_DESTROY:
364                 ret = uhid_dev_destroy(uhid);
365                 break;
366         case UHID_INPUT:
367                 ret = uhid_dev_input(uhid, &uhid->input_buf);
368                 break;
369         default:
370                 ret = -EOPNOTSUPP;
371         }
372
373 unlock:
374         mutex_unlock(&uhid->devlock);
375
376         /* return "count" not "len" to not confuse the caller */
377         return ret ? ret : count;
378 }
379
380 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
381 {
382         struct uhid_device *uhid = file->private_data;
383
384         poll_wait(file, &uhid->waitq, wait);
385
386         if (uhid->head != uhid->tail)
387                 return POLLIN | POLLRDNORM;
388
389         return 0;
390 }
391
392 static const struct file_operations uhid_fops = {
393         .owner          = THIS_MODULE,
394         .open           = uhid_char_open,
395         .release        = uhid_char_release,
396         .read           = uhid_char_read,
397         .write          = uhid_char_write,
398         .poll           = uhid_char_poll,
399         .llseek         = no_llseek,
400 };
401
402 static struct miscdevice uhid_misc = {
403         .fops           = &uhid_fops,
404         .minor          = MISC_DYNAMIC_MINOR,
405         .name           = UHID_NAME,
406 };
407
408 static int __init uhid_init(void)
409 {
410         return misc_register(&uhid_misc);
411 }
412
413 static void __exit uhid_exit(void)
414 {
415         misc_deregister(&uhid_misc);
416 }
417
418 module_init(uhid_init);
419 module_exit(uhid_exit);
420 MODULE_LICENSE("GPL");
421 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
422 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");