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1ccd7a2a DH |
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" | |
ace3d861 DH |
28 | #define UHID_BUFSIZE 32 |
29 | ||
30 | struct uhid_device { | |
d937ae5f | 31 | struct mutex devlock; |
d365c6cf DH |
32 | bool running; |
33 | ||
34 | __u8 *rd_data; | |
35 | uint rd_size; | |
36 | ||
ace3d861 | 37 | struct hid_device *hid; |
6664ef72 | 38 | struct uhid_event input_buf; |
ace3d861 DH |
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 | }; | |
1ccd7a2a DH |
46 | |
47 | static struct miscdevice uhid_misc; | |
48 | ||
ace3d861 DH |
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 | ||
d365c6cf DH |
83 | static int uhid_hid_start(struct hid_device *hid) |
84 | { | |
85 | return 0; | |
86 | } | |
87 | ||
88 | static void uhid_hid_stop(struct hid_device *hid) | |
89 | { | |
90 | } | |
91 | ||
92 | static int uhid_hid_open(struct hid_device *hid) | |
93 | { | |
94 | return 0; | |
95 | } | |
96 | ||
97 | static void uhid_hid_close(struct hid_device *hid) | |
98 | { | |
99 | } | |
100 | ||
101 | static int uhid_hid_input(struct input_dev *input, unsigned int type, | |
102 | unsigned int code, int value) | |
103 | { | |
104 | return 0; | |
105 | } | |
106 | ||
107 | static int uhid_hid_parse(struct hid_device *hid) | |
108 | { | |
109 | return 0; | |
110 | } | |
111 | ||
112 | static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum, | |
113 | __u8 *buf, size_t count, unsigned char rtype) | |
114 | { | |
115 | return 0; | |
116 | } | |
117 | ||
118 | static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count, | |
119 | unsigned char report_type) | |
120 | { | |
121 | return 0; | |
122 | } | |
123 | ||
124 | static struct hid_ll_driver uhid_hid_driver = { | |
125 | .start = uhid_hid_start, | |
126 | .stop = uhid_hid_stop, | |
127 | .open = uhid_hid_open, | |
128 | .close = uhid_hid_close, | |
129 | .hidinput_input_event = uhid_hid_input, | |
130 | .parse = uhid_hid_parse, | |
131 | }; | |
132 | ||
133 | static int uhid_dev_create(struct uhid_device *uhid, | |
134 | const struct uhid_event *ev) | |
135 | { | |
136 | struct hid_device *hid; | |
137 | int ret; | |
138 | ||
139 | if (uhid->running) | |
140 | return -EALREADY; | |
141 | ||
142 | uhid->rd_size = ev->u.create.rd_size; | |
143 | if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE) | |
144 | return -EINVAL; | |
145 | ||
146 | uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL); | |
147 | if (!uhid->rd_data) | |
148 | return -ENOMEM; | |
149 | ||
150 | if (copy_from_user(uhid->rd_data, ev->u.create.rd_data, | |
151 | uhid->rd_size)) { | |
152 | ret = -EFAULT; | |
153 | goto err_free; | |
154 | } | |
155 | ||
156 | hid = hid_allocate_device(); | |
157 | if (IS_ERR(hid)) { | |
158 | ret = PTR_ERR(hid); | |
159 | goto err_free; | |
160 | } | |
161 | ||
162 | strncpy(hid->name, ev->u.create.name, 127); | |
163 | hid->name[127] = 0; | |
164 | strncpy(hid->phys, ev->u.create.phys, 63); | |
165 | hid->phys[63] = 0; | |
166 | strncpy(hid->uniq, ev->u.create.uniq, 63); | |
167 | hid->uniq[63] = 0; | |
168 | ||
169 | hid->ll_driver = &uhid_hid_driver; | |
170 | hid->hid_get_raw_report = uhid_hid_get_raw; | |
171 | hid->hid_output_raw_report = uhid_hid_output_raw; | |
172 | hid->bus = ev->u.create.bus; | |
173 | hid->vendor = ev->u.create.vendor; | |
174 | hid->product = ev->u.create.product; | |
175 | hid->version = ev->u.create.version; | |
176 | hid->country = ev->u.create.country; | |
177 | hid->driver_data = uhid; | |
178 | hid->dev.parent = uhid_misc.this_device; | |
179 | ||
180 | uhid->hid = hid; | |
181 | uhid->running = true; | |
182 | ||
183 | ret = hid_add_device(hid); | |
184 | if (ret) { | |
185 | hid_err(hid, "Cannot register HID device\n"); | |
186 | goto err_hid; | |
187 | } | |
188 | ||
189 | return 0; | |
190 | ||
191 | err_hid: | |
192 | hid_destroy_device(hid); | |
193 | uhid->hid = NULL; | |
194 | uhid->running = false; | |
195 | err_free: | |
196 | kfree(uhid->rd_data); | |
197 | return ret; | |
198 | } | |
199 | ||
200 | static int uhid_dev_destroy(struct uhid_device *uhid) | |
201 | { | |
202 | if (!uhid->running) | |
203 | return -EINVAL; | |
204 | ||
205 | uhid->running = false; | |
206 | ||
207 | hid_destroy_device(uhid->hid); | |
208 | kfree(uhid->rd_data); | |
209 | ||
210 | return 0; | |
211 | } | |
212 | ||
5e87a36a DH |
213 | static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev) |
214 | { | |
215 | if (!uhid->running) | |
216 | return -EINVAL; | |
217 | ||
218 | hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data, | |
219 | min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0); | |
220 | ||
221 | return 0; | |
222 | } | |
223 | ||
1ccd7a2a DH |
224 | static int uhid_char_open(struct inode *inode, struct file *file) |
225 | { | |
ace3d861 DH |
226 | struct uhid_device *uhid; |
227 | ||
228 | uhid = kzalloc(sizeof(*uhid), GFP_KERNEL); | |
229 | if (!uhid) | |
230 | return -ENOMEM; | |
231 | ||
d937ae5f | 232 | mutex_init(&uhid->devlock); |
ace3d861 DH |
233 | spin_lock_init(&uhid->qlock); |
234 | init_waitqueue_head(&uhid->waitq); | |
d365c6cf | 235 | uhid->running = false; |
ace3d861 DH |
236 | |
237 | file->private_data = uhid; | |
238 | nonseekable_open(inode, file); | |
239 | ||
1ccd7a2a DH |
240 | return 0; |
241 | } | |
242 | ||
243 | static int uhid_char_release(struct inode *inode, struct file *file) | |
244 | { | |
ace3d861 DH |
245 | struct uhid_device *uhid = file->private_data; |
246 | unsigned int i; | |
247 | ||
d365c6cf DH |
248 | uhid_dev_destroy(uhid); |
249 | ||
ace3d861 DH |
250 | for (i = 0; i < UHID_BUFSIZE; ++i) |
251 | kfree(uhid->outq[i]); | |
252 | ||
253 | kfree(uhid); | |
254 | ||
1ccd7a2a DH |
255 | return 0; |
256 | } | |
257 | ||
258 | static ssize_t uhid_char_read(struct file *file, char __user *buffer, | |
259 | size_t count, loff_t *ppos) | |
260 | { | |
d937ae5f DH |
261 | struct uhid_device *uhid = file->private_data; |
262 | int ret; | |
263 | unsigned long flags; | |
264 | size_t len; | |
265 | ||
266 | /* they need at least the "type" member of uhid_event */ | |
267 | if (count < sizeof(__u32)) | |
268 | return -EINVAL; | |
269 | ||
270 | try_again: | |
271 | if (file->f_flags & O_NONBLOCK) { | |
272 | if (uhid->head == uhid->tail) | |
273 | return -EAGAIN; | |
274 | } else { | |
275 | ret = wait_event_interruptible(uhid->waitq, | |
276 | uhid->head != uhid->tail); | |
277 | if (ret) | |
278 | return ret; | |
279 | } | |
280 | ||
281 | ret = mutex_lock_interruptible(&uhid->devlock); | |
282 | if (ret) | |
283 | return ret; | |
284 | ||
285 | if (uhid->head == uhid->tail) { | |
286 | mutex_unlock(&uhid->devlock); | |
287 | goto try_again; | |
288 | } else { | |
289 | len = min(count, sizeof(**uhid->outq)); | |
290 | if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) { | |
291 | ret = -EFAULT; | |
292 | } else { | |
293 | kfree(uhid->outq[uhid->tail]); | |
294 | uhid->outq[uhid->tail] = NULL; | |
295 | ||
296 | spin_lock_irqsave(&uhid->qlock, flags); | |
297 | uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE; | |
298 | spin_unlock_irqrestore(&uhid->qlock, flags); | |
299 | } | |
300 | } | |
301 | ||
302 | mutex_unlock(&uhid->devlock); | |
303 | return ret ? ret : len; | |
1ccd7a2a DH |
304 | } |
305 | ||
306 | static ssize_t uhid_char_write(struct file *file, const char __user *buffer, | |
307 | size_t count, loff_t *ppos) | |
308 | { | |
6664ef72 DH |
309 | struct uhid_device *uhid = file->private_data; |
310 | int ret; | |
311 | size_t len; | |
312 | ||
313 | /* we need at least the "type" member of uhid_event */ | |
314 | if (count < sizeof(__u32)) | |
315 | return -EINVAL; | |
316 | ||
317 | ret = mutex_lock_interruptible(&uhid->devlock); | |
318 | if (ret) | |
319 | return ret; | |
320 | ||
321 | memset(&uhid->input_buf, 0, sizeof(uhid->input_buf)); | |
322 | len = min(count, sizeof(uhid->input_buf)); | |
323 | if (copy_from_user(&uhid->input_buf, buffer, len)) { | |
324 | ret = -EFAULT; | |
325 | goto unlock; | |
326 | } | |
327 | ||
328 | switch (uhid->input_buf.type) { | |
d365c6cf DH |
329 | case UHID_CREATE: |
330 | ret = uhid_dev_create(uhid, &uhid->input_buf); | |
331 | break; | |
332 | case UHID_DESTROY: | |
333 | ret = uhid_dev_destroy(uhid); | |
334 | break; | |
5e87a36a DH |
335 | case UHID_INPUT: |
336 | ret = uhid_dev_input(uhid, &uhid->input_buf); | |
337 | break; | |
6664ef72 DH |
338 | default: |
339 | ret = -EOPNOTSUPP; | |
340 | } | |
341 | ||
342 | unlock: | |
343 | mutex_unlock(&uhid->devlock); | |
344 | ||
345 | /* return "count" not "len" to not confuse the caller */ | |
346 | return ret ? ret : count; | |
1ccd7a2a DH |
347 | } |
348 | ||
349 | static unsigned int uhid_char_poll(struct file *file, poll_table *wait) | |
350 | { | |
1f9dec1e DH |
351 | struct uhid_device *uhid = file->private_data; |
352 | ||
353 | poll_wait(file, &uhid->waitq, wait); | |
354 | ||
355 | if (uhid->head != uhid->tail) | |
356 | return POLLIN | POLLRDNORM; | |
357 | ||
1ccd7a2a DH |
358 | return 0; |
359 | } | |
360 | ||
361 | static const struct file_operations uhid_fops = { | |
362 | .owner = THIS_MODULE, | |
363 | .open = uhid_char_open, | |
364 | .release = uhid_char_release, | |
365 | .read = uhid_char_read, | |
366 | .write = uhid_char_write, | |
367 | .poll = uhid_char_poll, | |
368 | .llseek = no_llseek, | |
369 | }; | |
370 | ||
371 | static struct miscdevice uhid_misc = { | |
372 | .fops = &uhid_fops, | |
373 | .minor = MISC_DYNAMIC_MINOR, | |
374 | .name = UHID_NAME, | |
375 | }; | |
376 | ||
377 | static int __init uhid_init(void) | |
378 | { | |
379 | return misc_register(&uhid_misc); | |
380 | } | |
381 | ||
382 | static void __exit uhid_exit(void) | |
383 | { | |
384 | misc_deregister(&uhid_misc); | |
385 | } | |
386 | ||
387 | module_init(uhid_init); | |
388 | module_exit(uhid_exit); | |
389 | MODULE_LICENSE("GPL"); | |
390 | MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); | |
391 | MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); |