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HID: roccat: propagate special events of roccat hardware to userspace
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1/*
2 * Roccat driver for Linux
3 *
4 * Copyright (c) 2010 Stefan Achatz <erazor_de@users.sourceforge.net>
5 */
6
7/*
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 */
13
14/*
15 * Module roccat is a char device used to report special events of roccat
16 * hardware to userland. These events include requests for on-screen-display of
17 * profile or dpi settings or requests for execution of macro sequences that are
18 * not stored in device. The information in these events depends on hid device
19 * implementation and contains data that is not available in a single hid event
20 * or else hidraw could have been used.
21 * It is inspired by hidraw, but uses only one circular buffer for all readers.
22 */
23
24#include <linux/cdev.h>
25#include <linux/poll.h>
26#include <linux/sched.h>
27
28#include "hid-roccat.h"
29
30#define ROCCAT_FIRST_MINOR 0
31#define ROCCAT_MAX_DEVICES 8
32
33/* should be a power of 2 for performance reason */
34#define ROCCAT_CBUF_SIZE 16
35
36struct roccat_report {
37 uint8_t *value;
38 int len;
39};
40
41struct roccat_device {
42 unsigned int minor;
43 int open;
44 int exist;
45 wait_queue_head_t wait;
46 struct device *dev;
47 struct hid_device *hid;
48 struct list_head readers;
49 /* protects modifications of readers list */
50 struct mutex readers_lock;
51
52 /*
53 * circular_buffer has one writer and multiple readers with their own
54 * read pointers
55 */
56 struct roccat_report cbuf[ROCCAT_CBUF_SIZE];
57 int cbuf_end;
58 struct mutex cbuf_lock;
59};
60
61struct roccat_reader {
62 struct list_head node;
63 struct roccat_device *device;
64 int cbuf_start;
65};
66
67static int roccat_major;
68static struct class *roccat_class;
69static struct cdev roccat_cdev;
70
71static struct roccat_device *devices[ROCCAT_MAX_DEVICES];
72/* protects modifications of devices array */
73static DEFINE_MUTEX(devices_lock);
74
75static ssize_t roccat_read(struct file *file, char __user *buffer,
76 size_t count, loff_t *ppos)
77{
78 struct roccat_reader *reader = file->private_data;
79 struct roccat_device *device = reader->device;
80 struct roccat_report *report;
81 ssize_t retval = 0, len;
82 DECLARE_WAITQUEUE(wait, current);
83
84 mutex_lock(&device->cbuf_lock);
85
86 /* no data? */
87 if (reader->cbuf_start == device->cbuf_end) {
88 add_wait_queue(&device->wait, &wait);
89 set_current_state(TASK_INTERRUPTIBLE);
90
91 /* wait for data */
92 while (reader->cbuf_start == device->cbuf_end) {
93 if (file->f_flags & O_NONBLOCK) {
94 retval = -EAGAIN;
95 break;
96 }
97 if (signal_pending(current)) {
98 retval = -ERESTARTSYS;
99 break;
100 }
101 if (!device->exist) {
102 retval = -EIO;
103 break;
104 }
105
106 mutex_unlock(&device->cbuf_lock);
107 schedule();
108 mutex_lock(&device->cbuf_lock);
109 set_current_state(TASK_INTERRUPTIBLE);
110 }
111
112 set_current_state(TASK_RUNNING);
113 remove_wait_queue(&device->wait, &wait);
114 }
115
116 /* here we either have data or a reason to return if retval is set */
117 if (retval)
118 goto exit_unlock;
119
120 report = &device->cbuf[reader->cbuf_start];
121 /*
122 * If report is larger than requested amount of data, rest of report
123 * is lost!
124 */
125 len = report->len > count ? count : report->len;
126
127 if (copy_to_user(buffer, report->value, len)) {
128 retval = -EFAULT;
129 goto exit_unlock;
130 }
131 retval += len;
132 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
133
134exit_unlock:
135 mutex_unlock(&device->cbuf_lock);
136 return retval;
137}
138
139static unsigned int roccat_poll(struct file *file, poll_table *wait)
140{
141 struct roccat_reader *reader = file->private_data;
142 poll_wait(file, &reader->device->wait, wait);
143 if (reader->cbuf_start != reader->device->cbuf_end)
144 return POLLIN | POLLRDNORM;
145 if (!reader->device->exist)
146 return POLLERR | POLLHUP;
147 return 0;
148}
149
150static int roccat_open(struct inode *inode, struct file *file)
151{
152 unsigned int minor = iminor(inode);
153 struct roccat_reader *reader;
154 struct roccat_device *device;
155 int error = 0;
156
157 reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL);
158 if (!reader)
159 return -ENOMEM;
160
161 mutex_lock(&devices_lock);
162
163 device = devices[minor];
164
165 mutex_lock(&device->readers_lock);
166
167 if (!device) {
168 printk(KERN_EMERG "roccat device with minor %d doesn't exist\n",
169 minor);
170 error = -ENODEV;
171 goto exit_unlock;
172 }
173
174 if (!device->open++) {
175 /* power on device on adding first reader */
176 if (device->hid->ll_driver->power) {
177 error = device->hid->ll_driver->power(device->hid,
178 PM_HINT_FULLON);
179 if (error < 0) {
180 --device->open;
181 goto exit_unlock;
182 }
183 }
184 error = device->hid->ll_driver->open(device->hid);
185 if (error < 0) {
186 if (device->hid->ll_driver->power)
187 device->hid->ll_driver->power(device->hid,
188 PM_HINT_NORMAL);
189 --device->open;
190 goto exit_unlock;
191 }
192 }
193
194 reader->device = device;
195 /* new reader doesn't get old events */
196 reader->cbuf_start = device->cbuf_end;
197
198 list_add_tail(&reader->node, &device->readers);
199 file->private_data = reader;
200
201exit_unlock:
202 mutex_unlock(&device->readers_lock);
203 mutex_unlock(&devices_lock);
204 return error;
205}
206
207static int roccat_release(struct inode *inode, struct file *file)
208{
209 unsigned int minor = iminor(inode);
210 struct roccat_reader *reader = file->private_data;
211 struct roccat_device *device;
212
213 mutex_lock(&devices_lock);
214
215 device = devices[minor];
216 if (!device) {
217 mutex_unlock(&devices_lock);
218 printk(KERN_EMERG "roccat device with minor %d doesn't exist\n",
219 minor);
220 return -ENODEV;
221 }
222
223 mutex_lock(&device->readers_lock);
224 list_del(&reader->node);
225 mutex_unlock(&device->readers_lock);
226 kfree(reader);
227
228 if (!--device->open) {
229 /* removing last reader */
230 if (device->exist) {
231 if (device->hid->ll_driver->power)
232 device->hid->ll_driver->power(device->hid,
233 PM_HINT_NORMAL);
234 device->hid->ll_driver->close(device->hid);
235 } else {
236 kfree(device);
237 }
238 }
239
240 mutex_unlock(&devices_lock);
241
242 return 0;
243}
244
245/*
246 * roccat_report_event() - output data to readers
247 * @minor: minor device number returned by roccat_connect()
248 * @data: pointer to data
249 * @len: size of data
250 *
251 * Return value is zero on success, a negative error code on failure.
252 *
253 * This is called from interrupt handler.
254 */
255int roccat_report_event(int minor, u8 const *data, int len)
256{
257 struct roccat_device *device;
258 struct roccat_reader *reader;
259 struct roccat_report *report;
260 uint8_t *new_value;
261
262 new_value = kmemdup(data, len, GFP_ATOMIC);
263 if (!new_value)
264 return -ENOMEM;
265
266 device = devices[minor];
267
268 report = &device->cbuf[device->cbuf_end];
269
270 /* passing NULL is safe */
271 kfree(report->value);
272
273 report->value = new_value;
274 report->len = len;
275 device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
276
277 list_for_each_entry(reader, &device->readers, node) {
278 /*
279 * As we already inserted one element, the buffer can't be
280 * empty. If start and end are equal, buffer is full and we
281 * increase start, so that slow reader misses one event, but
282 * gets the newer ones in the right order.
283 */
284 if (reader->cbuf_start == device->cbuf_end)
285 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
286 }
287
288 wake_up_interruptible(&device->wait);
289 return 0;
290}
291EXPORT_SYMBOL_GPL(roccat_report_event);
292
293/*
294 * roccat_connect() - create a char device for special event output
295 * @hid: the hid device the char device should be connected to.
296 *
297 * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
298 * success, a negative error code on failure.
299 */
300int roccat_connect(struct hid_device *hid)
301{
302 unsigned int minor;
303 struct roccat_device *device;
304 int temp;
305
306 device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
307 if (!device)
308 return -ENOMEM;
309
310 mutex_lock(&devices_lock);
311
312 for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
313 if (devices[minor])
314 continue;
315 break;
316 }
317
318 if (minor < ROCCAT_MAX_DEVICES) {
319 devices[minor] = device;
320 } else {
321 mutex_unlock(&devices_lock);
322 kfree(device);
323 return -EINVAL;
324 }
325
326 device->dev = device_create(roccat_class, &hid->dev,
327 MKDEV(roccat_major, minor), NULL,
328 "%s%s%d", "roccat", hid->driver->name, minor);
329
330 if (IS_ERR(device->dev)) {
331 devices[minor] = NULL;
332 mutex_unlock(&devices_lock);
333 temp = PTR_ERR(device->dev);
334 kfree(device);
335 return temp;
336 }
337
338 mutex_unlock(&devices_lock);
339
340 init_waitqueue_head(&device->wait);
341 INIT_LIST_HEAD(&device->readers);
342 mutex_init(&device->readers_lock);
343 mutex_init(&device->cbuf_lock);
344 device->minor = minor;
345 device->hid = hid;
346 device->exist = 1;
347 device->cbuf_end = 0;
348
349 return minor;
350}
351EXPORT_SYMBOL_GPL(roccat_connect);
352
353/* roccat_disconnect() - remove char device from hid device
354 * @minor: the minor device number returned by roccat_connect()
355 */
356void roccat_disconnect(int minor)
357{
358 struct roccat_device *device;
359
360 mutex_lock(&devices_lock);
361 device = devices[minor];
362 devices[minor] = NULL;
363 mutex_unlock(&devices_lock);
364
365 device->exist = 0; /* TODO exist maybe not needed */
366
367 device_destroy(roccat_class, MKDEV(roccat_major, minor));
368
369 if (device->open) {
370 device->hid->ll_driver->close(device->hid);
371 wake_up_interruptible(&device->wait);
372 } else {
373 kfree(device);
374 }
375}
376EXPORT_SYMBOL_GPL(roccat_disconnect);
377
378static const struct file_operations roccat_ops = {
379 .owner = THIS_MODULE,
380 .read = roccat_read,
381 .poll = roccat_poll,
382 .open = roccat_open,
383 .release = roccat_release,
384};
385
386static int __init roccat_init(void)
387{
388 int retval;
389 dev_t dev_id;
390
391 retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
392 ROCCAT_MAX_DEVICES, "roccat");
393
394 roccat_major = MAJOR(dev_id);
395
396 if (retval < 0) {
397 printk(KERN_WARNING "roccat: can't get major number\n");
398 return retval;
399 }
400
401 roccat_class = class_create(THIS_MODULE, "roccat");
402 if (IS_ERR(roccat_class)) {
403 retval = PTR_ERR(roccat_class);
404 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
405 return retval;
406 }
407
408 cdev_init(&roccat_cdev, &roccat_ops);
409 cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
410
411 return 0;
412}
413
414static void __exit roccat_exit(void)
415{
416 dev_t dev_id = MKDEV(roccat_major, 0);
417
418 cdev_del(&roccat_cdev);
419 class_destroy(roccat_class);
420 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
421}
422
423module_init(roccat_init);
424module_exit(roccat_exit);
425
426MODULE_AUTHOR("Stefan Achatz");
427MODULE_DESCRIPTION("USB Roccat char device");
428MODULE_LICENSE("GPL v2");