summaryrefslogtreecommitdiff
path: root/drivers/hid/uhid.c
blob: 61ee7cc32ccfc7d62129aaa6b947c0bb137d8863 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
/*
 * User-space I/O driver support for HID subsystem
 * Copyright (c) 2012 David Herrmann
 */

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 */

#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/hid.h>
#include <linux/input.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/uhid.h>
#include <linux/wait.h>

#define UHID_NAME	"uhid"
#define UHID_BUFSIZE	32

struct uhid_device {
	struct mutex devlock;
	bool running;

	__u8 *rd_data;
	uint rd_size;

	struct hid_device *hid;
	struct uhid_event input_buf;

	wait_queue_head_t waitq;
	spinlock_t qlock;
	__u8 head;
	__u8 tail;
	struct uhid_event *outq[UHID_BUFSIZE];
};

static struct miscdevice uhid_misc;

static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
{
	__u8 newhead;

	newhead = (uhid->head + 1) % UHID_BUFSIZE;

	if (newhead != uhid->tail) {
		uhid->outq[uhid->head] = ev;
		uhid->head = newhead;
		wake_up_interruptible(&uhid->waitq);
	} else {
		hid_warn(uhid->hid, "Output queue is full\n");
		kfree(ev);
	}
}

static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
{
	unsigned long flags;
	struct uhid_event *ev;

	ev = kzalloc(sizeof(*ev), GFP_KERNEL);
	if (!ev)
		return -ENOMEM;

	ev->type = event;

	spin_lock_irqsave(&uhid->qlock, flags);
	uhid_queue(uhid, ev);
	spin_unlock_irqrestore(&uhid->qlock, flags);

	return 0;
}

static int uhid_hid_start(struct hid_device *hid)
{
	return 0;
}

static void uhid_hid_stop(struct hid_device *hid)
{
}

static int uhid_hid_open(struct hid_device *hid)
{
	return 0;
}

static void uhid_hid_close(struct hid_device *hid)
{
}

static int uhid_hid_input(struct input_dev *input, unsigned int type,
			  unsigned int code, int value)
{
	return 0;
}

static int uhid_hid_parse(struct hid_device *hid)
{
	return 0;
}

static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
			    __u8 *buf, size_t count, unsigned char rtype)
{
	return 0;
}

static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
			       unsigned char report_type)
{
	return 0;
}

static struct hid_ll_driver uhid_hid_driver = {
	.start = uhid_hid_start,
	.stop = uhid_hid_stop,
	.open = uhid_hid_open,
	.close = uhid_hid_close,
	.hidinput_input_event = uhid_hid_input,
	.parse = uhid_hid_parse,
};

static int uhid_dev_create(struct uhid_device *uhid,
			   const struct uhid_event *ev)
{
	struct hid_device *hid;
	int ret;

	if (uhid->running)
		return -EALREADY;

	uhid->rd_size = ev->u.create.rd_size;
	if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
		return -EINVAL;

	uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
	if (!uhid->rd_data)
		return -ENOMEM;

	if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
			   uhid->rd_size)) {
		ret = -EFAULT;
		goto err_free;
	}

	hid = hid_allocate_device();
	if (IS_ERR(hid)) {
		ret = PTR_ERR(hid);
		goto err_free;
	}

	strncpy(hid->name, ev->u.create.name, 127);
	hid->name[127] = 0;
	strncpy(hid->phys, ev->u.create.phys, 63);
	hid->phys[63] = 0;
	strncpy(hid->uniq, ev->u.create.uniq, 63);
	hid->uniq[63] = 0;

	hid->ll_driver = &uhid_hid_driver;
	hid->hid_get_raw_report = uhid_hid_get_raw;
	hid->hid_output_raw_report = uhid_hid_output_raw;
	hid->bus = ev->u.create.bus;
	hid->vendor = ev->u.create.vendor;
	hid->product = ev->u.create.product;
	hid->version = ev->u.create.version;
	hid->country = ev->u.create.country;
	hid->driver_data = uhid;
	hid->dev.parent = uhid_misc.this_device;

	uhid->hid = hid;
	uhid->running = true;

	ret = hid_add_device(hid);
	if (ret) {
		hid_err(hid, "Cannot register HID device\n");
		goto err_hid;
	}

	return 0;

err_hid:
	hid_destroy_device(hid);
	uhid->hid = NULL;
	uhid->running = false;
err_free:
	kfree(uhid->rd_data);
	return ret;
}

static int uhid_dev_destroy(struct uhid_device *uhid)
{
	if (!uhid->running)
		return -EINVAL;

	uhid->running = false;

	hid_destroy_device(uhid->hid);
	kfree(uhid->rd_data);

	return 0;
}

static int uhid_char_open(struct inode *inode, struct file *file)
{
	struct uhid_device *uhid;

	uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
	if (!uhid)
		return -ENOMEM;

	mutex_init(&uhid->devlock);
	spin_lock_init(&uhid->qlock);
	init_waitqueue_head(&uhid->waitq);
	uhid->running = false;

	file->private_data = uhid;
	nonseekable_open(inode, file);

	return 0;
}

static int uhid_char_release(struct inode *inode, struct file *file)
{
	struct uhid_device *uhid = file->private_data;
	unsigned int i;

	uhid_dev_destroy(uhid);

	for (i = 0; i < UHID_BUFSIZE; ++i)
		kfree(uhid->outq[i]);

	kfree(uhid);

	return 0;
}

static ssize_t uhid_char_read(struct file *file, char __user *buffer,
				size_t count, loff_t *ppos)
{
	struct uhid_device *uhid = file->private_data;
	int ret;
	unsigned long flags;
	size_t len;

	/* they need at least the "type" member of uhid_event */
	if (count < sizeof(__u32))
		return -EINVAL;

try_again:
	if (file->f_flags & O_NONBLOCK) {
		if (uhid->head == uhid->tail)
			return -EAGAIN;
	} else {
		ret = wait_event_interruptible(uhid->waitq,
						uhid->head != uhid->tail);
		if (ret)
			return ret;
	}

	ret = mutex_lock_interruptible(&uhid->devlock);
	if (ret)
		return ret;

	if (uhid->head == uhid->tail) {
		mutex_unlock(&uhid->devlock);
		goto try_again;
	} else {
		len = min(count, sizeof(**uhid->outq));
		if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) {
			ret = -EFAULT;
		} else {
			kfree(uhid->outq[uhid->tail]);
			uhid->outq[uhid->tail] = NULL;

			spin_lock_irqsave(&uhid->qlock, flags);
			uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
			spin_unlock_irqrestore(&uhid->qlock, flags);
		}
	}

	mutex_unlock(&uhid->devlock);
	return ret ? ret : len;
}

static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
				size_t count, loff_t *ppos)
{
	struct uhid_device *uhid = file->private_data;
	int ret;
	size_t len;

	/* we need at least the "type" member of uhid_event */
	if (count < sizeof(__u32))
		return -EINVAL;

	ret = mutex_lock_interruptible(&uhid->devlock);
	if (ret)
		return ret;

	memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
	len = min(count, sizeof(uhid->input_buf));
	if (copy_from_user(&uhid->input_buf, buffer, len)) {
		ret = -EFAULT;
		goto unlock;
	}

	switch (uhid->input_buf.type) {
	case UHID_CREATE:
		ret = uhid_dev_create(uhid, &uhid->input_buf);
		break;
	case UHID_DESTROY:
		ret = uhid_dev_destroy(uhid);
		break;
	default:
		ret = -EOPNOTSUPP;
	}

unlock:
	mutex_unlock(&uhid->devlock);

	/* return "count" not "len" to not confuse the caller */
	return ret ? ret : count;
}

static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
{
	struct uhid_device *uhid = file->private_data;

	poll_wait(file, &uhid->waitq, wait);

	if (uhid->head != uhid->tail)
		return POLLIN | POLLRDNORM;

	return 0;
}

static const struct file_operations uhid_fops = {
	.owner		= THIS_MODULE,
	.open		= uhid_char_open,
	.release	= uhid_char_release,
	.read		= uhid_char_read,
	.write		= uhid_char_write,
	.poll		= uhid_char_poll,
	.llseek		= no_llseek,
};

static struct miscdevice uhid_misc = {
	.fops		= &uhid_fops,
	.minor		= MISC_DYNAMIC_MINOR,
	.name		= UHID_NAME,
};

static int __init uhid_init(void)
{
	return misc_register(&uhid_misc);
}

static void __exit uhid_exit(void)
{
	misc_deregister(&uhid_misc);
}

module_init(uhid_init);
module_exit(uhid_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");