2 * User-space I/O driver support for HID subsystem
3 * Copyright (c) 2012 David Herrmann
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)
13 #include <linux/atomic.h>
14 #include <linux/device.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>
27 #define UHID_NAME "uhid"
28 #define UHID_BUFSIZE 32
37 struct hid_device *hid;
38 struct uhid_event input_buf;
40 wait_queue_head_t waitq;
44 struct uhid_event *outq[UHID_BUFSIZE];
47 static struct miscdevice uhid_misc;
49 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
53 newhead = (uhid->head + 1) % UHID_BUFSIZE;
55 if (newhead != uhid->tail) {
56 uhid->outq[uhid->head] = ev;
58 wake_up_interruptible(&uhid->waitq);
60 hid_warn(uhid->hid, "Output queue is full\n");
65 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
68 struct uhid_event *ev;
70 ev = kzalloc(sizeof(*ev), GFP_KERNEL);
76 spin_lock_irqsave(&uhid->qlock, flags);
78 spin_unlock_irqrestore(&uhid->qlock, flags);
83 static int uhid_hid_start(struct hid_device *hid)
88 static void uhid_hid_stop(struct hid_device *hid)
92 static int uhid_hid_open(struct hid_device *hid)
97 static void uhid_hid_close(struct hid_device *hid)
101 static int uhid_hid_input(struct input_dev *input, unsigned int type,
102 unsigned int code, int value)
107 static int uhid_hid_parse(struct hid_device *hid)
112 static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
113 __u8 *buf, size_t count, unsigned char rtype)
118 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
119 unsigned char report_type)
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,
133 static int uhid_dev_create(struct uhid_device *uhid,
134 const struct uhid_event *ev)
136 struct hid_device *hid;
142 uhid->rd_size = ev->u.create.rd_size;
143 if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
146 uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
150 if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
156 hid = hid_allocate_device();
162 strncpy(hid->name, ev->u.create.name, 127);
164 strncpy(hid->phys, ev->u.create.phys, 63);
166 strncpy(hid->uniq, ev->u.create.uniq, 63);
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;
181 uhid->running = true;
183 ret = hid_add_device(hid);
185 hid_err(hid, "Cannot register HID device\n");
192 hid_destroy_device(hid);
194 uhid->running = false;
196 kfree(uhid->rd_data);
200 static int uhid_dev_destroy(struct uhid_device *uhid)
205 uhid->running = false;
207 hid_destroy_device(uhid->hid);
208 kfree(uhid->rd_data);
213 static int uhid_char_open(struct inode *inode, struct file *file)
215 struct uhid_device *uhid;
217 uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
221 mutex_init(&uhid->devlock);
222 spin_lock_init(&uhid->qlock);
223 init_waitqueue_head(&uhid->waitq);
224 uhid->running = false;
226 file->private_data = uhid;
227 nonseekable_open(inode, file);
232 static int uhid_char_release(struct inode *inode, struct file *file)
234 struct uhid_device *uhid = file->private_data;
237 uhid_dev_destroy(uhid);
239 for (i = 0; i < UHID_BUFSIZE; ++i)
240 kfree(uhid->outq[i]);
247 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
248 size_t count, loff_t *ppos)
250 struct uhid_device *uhid = file->private_data;
255 /* they need at least the "type" member of uhid_event */
256 if (count < sizeof(__u32))
260 if (file->f_flags & O_NONBLOCK) {
261 if (uhid->head == uhid->tail)
264 ret = wait_event_interruptible(uhid->waitq,
265 uhid->head != uhid->tail);
270 ret = mutex_lock_interruptible(&uhid->devlock);
274 if (uhid->head == uhid->tail) {
275 mutex_unlock(&uhid->devlock);
278 len = min(count, sizeof(**uhid->outq));
279 if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) {
282 kfree(uhid->outq[uhid->tail]);
283 uhid->outq[uhid->tail] = NULL;
285 spin_lock_irqsave(&uhid->qlock, flags);
286 uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
287 spin_unlock_irqrestore(&uhid->qlock, flags);
291 mutex_unlock(&uhid->devlock);
292 return ret ? ret : len;
295 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
296 size_t count, loff_t *ppos)
298 struct uhid_device *uhid = file->private_data;
302 /* we need at least the "type" member of uhid_event */
303 if (count < sizeof(__u32))
306 ret = mutex_lock_interruptible(&uhid->devlock);
310 memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
311 len = min(count, sizeof(uhid->input_buf));
312 if (copy_from_user(&uhid->input_buf, buffer, len)) {
317 switch (uhid->input_buf.type) {
319 ret = uhid_dev_create(uhid, &uhid->input_buf);
322 ret = uhid_dev_destroy(uhid);
329 mutex_unlock(&uhid->devlock);
331 /* return "count" not "len" to not confuse the caller */
332 return ret ? ret : count;
335 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
337 struct uhid_device *uhid = file->private_data;
339 poll_wait(file, &uhid->waitq, wait);
341 if (uhid->head != uhid->tail)
342 return POLLIN | POLLRDNORM;
347 static const struct file_operations uhid_fops = {
348 .owner = THIS_MODULE,
349 .open = uhid_char_open,
350 .release = uhid_char_release,
351 .read = uhid_char_read,
352 .write = uhid_char_write,
353 .poll = uhid_char_poll,
357 static struct miscdevice uhid_misc = {
359 .minor = MISC_DYNAMIC_MINOR,
363 static int __init uhid_init(void)
365 return misc_register(&uhid_misc);
368 static void __exit uhid_exit(void)
370 misc_deregister(&uhid_misc);
373 module_init(uhid_init);
374 module_exit(uhid_exit);
375 MODULE_LICENSE("GPL");
376 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
377 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");