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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26 #include <linux/cdev.h>
27 #include <linux/poll.h>
28 #include <linux/sched/signal.h>
29 #include <linux/hid-roccat.h>
30 #include <linux/module.h>
31
32 #define ROCCAT_FIRST_MINOR 0
33 #define ROCCAT_MAX_DEVICES 8
34
35 /* should be a power of 2 for performance reason */
36 #define ROCCAT_CBUF_SIZE 16
37
38 struct roccat_report {
39 uint8_t *value;
40 };
41
42 struct roccat_device {
43 unsigned int minor;
44 int report_size;
45 int open;
46 int exist;
47 wait_queue_head_t wait;
48 struct device *dev;
49 struct hid_device *hid;
50 struct list_head readers;
51 /* protects modifications of readers list */
52 struct mutex readers_lock;
53
54 /*
55 * circular_buffer has one writer and multiple readers with their own
56 * read pointers
57 */
58 struct roccat_report cbuf[ROCCAT_CBUF_SIZE];
59 int cbuf_end;
60 struct mutex cbuf_lock;
61 };
62
63 struct roccat_reader {
64 struct list_head node;
65 struct roccat_device *device;
66 int cbuf_start;
67 };
68
69 static int roccat_major;
70 static struct cdev roccat_cdev;
71
72 static struct roccat_device *devices[ROCCAT_MAX_DEVICES];
73 /* protects modifications of devices array */
74 static DEFINE_MUTEX(devices_lock);
75
roccat_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)76 static ssize_t roccat_read(struct file *file, char __user *buffer,
77 size_t count, loff_t *ppos)
78 {
79 struct roccat_reader *reader = file->private_data;
80 struct roccat_device *device = reader->device;
81 struct roccat_report *report;
82 ssize_t retval = 0, len;
83 DECLARE_WAITQUEUE(wait, current);
84
85 mutex_lock(&device->cbuf_lock);
86
87 /* no data? */
88 if (reader->cbuf_start == device->cbuf_end) {
89 add_wait_queue(&device->wait, &wait);
90 set_current_state(TASK_INTERRUPTIBLE);
91
92 /* wait for data */
93 while (reader->cbuf_start == device->cbuf_end) {
94 if (file->f_flags & O_NONBLOCK) {
95 retval = -EAGAIN;
96 break;
97 }
98 if (signal_pending(current)) {
99 retval = -ERESTARTSYS;
100 break;
101 }
102 if (!device->exist) {
103 retval = -EIO;
104 break;
105 }
106
107 mutex_unlock(&device->cbuf_lock);
108 schedule();
109 mutex_lock(&device->cbuf_lock);
110 set_current_state(TASK_INTERRUPTIBLE);
111 }
112
113 set_current_state(TASK_RUNNING);
114 remove_wait_queue(&device->wait, &wait);
115 }
116
117 /* here we either have data or a reason to return if retval is set */
118 if (retval)
119 goto exit_unlock;
120
121 report = &device->cbuf[reader->cbuf_start];
122 /*
123 * If report is larger than requested amount of data, rest of report
124 * is lost!
125 */
126 len = device->report_size > count ? count : device->report_size;
127
128 if (copy_to_user(buffer, report->value, len)) {
129 retval = -EFAULT;
130 goto exit_unlock;
131 }
132 retval += len;
133 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
134
135 exit_unlock:
136 mutex_unlock(&device->cbuf_lock);
137 return retval;
138 }
139
roccat_poll(struct file * file,poll_table * wait)140 static __poll_t roccat_poll(struct file *file, poll_table *wait)
141 {
142 struct roccat_reader *reader = file->private_data;
143 poll_wait(file, &reader->device->wait, wait);
144 if (reader->cbuf_start != reader->device->cbuf_end)
145 return EPOLLIN | EPOLLRDNORM;
146 if (!reader->device->exist)
147 return EPOLLERR | EPOLLHUP;
148 return 0;
149 }
150
roccat_open(struct inode * inode,struct file * file)151 static int roccat_open(struct inode *inode, struct file *file)
152 {
153 unsigned int minor = iminor(inode);
154 struct roccat_reader *reader;
155 struct roccat_device *device;
156 int error = 0;
157
158 reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL);
159 if (!reader)
160 return -ENOMEM;
161
162 mutex_lock(&devices_lock);
163
164 device = devices[minor];
165
166 if (!device) {
167 pr_emerg("roccat device with minor %d doesn't exist\n", minor);
168 error = -ENODEV;
169 goto exit_err_devices;
170 }
171
172 mutex_lock(&device->readers_lock);
173
174 if (!device->open++) {
175 /* power on device on adding first reader */
176 error = hid_hw_power(device->hid, PM_HINT_FULLON);
177 if (error < 0) {
178 --device->open;
179 goto exit_err_readers;
180 }
181
182 error = hid_hw_open(device->hid);
183 if (error < 0) {
184 hid_hw_power(device->hid, PM_HINT_NORMAL);
185 --device->open;
186 goto exit_err_readers;
187 }
188 }
189
190 reader->device = device;
191 /* new reader doesn't get old events */
192 reader->cbuf_start = device->cbuf_end;
193
194 list_add_tail(&reader->node, &device->readers);
195 file->private_data = reader;
196
197 exit_err_readers:
198 mutex_unlock(&device->readers_lock);
199 exit_err_devices:
200 mutex_unlock(&devices_lock);
201 if (error)
202 kfree(reader);
203 return error;
204 }
205
roccat_release(struct inode * inode,struct file * file)206 static int roccat_release(struct inode *inode, struct file *file)
207 {
208 unsigned int minor = iminor(inode);
209 struct roccat_reader *reader = file->private_data;
210 struct roccat_device *device;
211
212 mutex_lock(&devices_lock);
213
214 device = devices[minor];
215 if (!device) {
216 mutex_unlock(&devices_lock);
217 pr_emerg("roccat device with minor %d doesn't exist\n", minor);
218 return -ENODEV;
219 }
220
221 mutex_lock(&device->readers_lock);
222 list_del(&reader->node);
223 mutex_unlock(&device->readers_lock);
224 kfree(reader);
225
226 if (!--device->open) {
227 /* removing last reader */
228 if (device->exist) {
229 hid_hw_power(device->hid, PM_HINT_NORMAL);
230 hid_hw_close(device->hid);
231 } else {
232 kfree(device);
233 }
234 }
235
236 mutex_unlock(&devices_lock);
237
238 return 0;
239 }
240
241 /*
242 * roccat_report_event() - output data to readers
243 * @minor: minor device number returned by roccat_connect()
244 * @data: pointer to data
245 *
246 * Return value is zero on success, a negative error code on failure.
247 *
248 * This is called from interrupt handler.
249 */
roccat_report_event(int minor,u8 const * data)250 int roccat_report_event(int minor, u8 const *data)
251 {
252 struct roccat_device *device;
253 struct roccat_reader *reader;
254 struct roccat_report *report;
255 uint8_t *new_value;
256
257 device = devices[minor];
258
259 new_value = kmemdup(data, device->report_size, GFP_ATOMIC);
260 if (!new_value)
261 return -ENOMEM;
262
263 mutex_lock(&device->cbuf_lock);
264
265 report = &device->cbuf[device->cbuf_end];
266
267 /* passing NULL is safe */
268 kfree(report->value);
269
270 report->value = new_value;
271 device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
272
273 list_for_each_entry(reader, &device->readers, node) {
274 /*
275 * As we already inserted one element, the buffer can't be
276 * empty. If start and end are equal, buffer is full and we
277 * increase start, so that slow reader misses one event, but
278 * gets the newer ones in the right order.
279 */
280 if (reader->cbuf_start == device->cbuf_end)
281 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
282 }
283
284 mutex_unlock(&device->cbuf_lock);
285
286 wake_up_interruptible(&device->wait);
287 return 0;
288 }
289 EXPORT_SYMBOL_GPL(roccat_report_event);
290
291 /*
292 * roccat_connect() - create a char device for special event output
293 * @class: the class thats used to create the device. Meant to hold device
294 * specific sysfs attributes.
295 * @hid: the hid device the char device should be connected to.
296 * @report_size: size of reports
297 *
298 * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
299 * success, a negative error code on failure.
300 */
roccat_connect(struct class * klass,struct hid_device * hid,int report_size)301 int roccat_connect(struct class *klass, struct hid_device *hid, int report_size)
302 {
303 unsigned int minor;
304 struct roccat_device *device;
305 int temp;
306
307 device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
308 if (!device)
309 return -ENOMEM;
310
311 mutex_lock(&devices_lock);
312
313 for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
314 if (devices[minor])
315 continue;
316 break;
317 }
318
319 if (minor < ROCCAT_MAX_DEVICES) {
320 devices[minor] = device;
321 } else {
322 mutex_unlock(&devices_lock);
323 kfree(device);
324 return -EINVAL;
325 }
326
327 device->dev = device_create(klass, &hid->dev,
328 MKDEV(roccat_major, minor), NULL,
329 "%s%s%d", "roccat", hid->driver->name, minor);
330
331 if (IS_ERR(device->dev)) {
332 devices[minor] = NULL;
333 mutex_unlock(&devices_lock);
334 temp = PTR_ERR(device->dev);
335 kfree(device);
336 return temp;
337 }
338
339 mutex_unlock(&devices_lock);
340
341 init_waitqueue_head(&device->wait);
342 INIT_LIST_HEAD(&device->readers);
343 mutex_init(&device->readers_lock);
344 mutex_init(&device->cbuf_lock);
345 device->minor = minor;
346 device->hid = hid;
347 device->exist = 1;
348 device->cbuf_end = 0;
349 device->report_size = report_size;
350
351 return minor;
352 }
353 EXPORT_SYMBOL_GPL(roccat_connect);
354
355 /* roccat_disconnect() - remove char device from hid device
356 * @minor: the minor device number returned by roccat_connect()
357 */
roccat_disconnect(int minor)358 void roccat_disconnect(int minor)
359 {
360 struct roccat_device *device;
361
362 mutex_lock(&devices_lock);
363 device = devices[minor];
364 mutex_unlock(&devices_lock);
365
366 device->exist = 0; /* TODO exist maybe not needed */
367
368 device_destroy(device->dev->class, MKDEV(roccat_major, minor));
369
370 mutex_lock(&devices_lock);
371 devices[minor] = NULL;
372 mutex_unlock(&devices_lock);
373
374 if (device->open) {
375 hid_hw_close(device->hid);
376 wake_up_interruptible(&device->wait);
377 } else {
378 kfree(device);
379 }
380 }
381 EXPORT_SYMBOL_GPL(roccat_disconnect);
382
roccat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)383 static long roccat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
384 {
385 struct inode *inode = file_inode(file);
386 struct roccat_device *device;
387 unsigned int minor = iminor(inode);
388 long retval = 0;
389
390 mutex_lock(&devices_lock);
391
392 device = devices[minor];
393 if (!device) {
394 retval = -ENODEV;
395 goto out;
396 }
397
398 switch (cmd) {
399 case ROCCATIOCGREPSIZE:
400 if (put_user(device->report_size, (int __user *)arg))
401 retval = -EFAULT;
402 break;
403 default:
404 retval = -ENOTTY;
405 }
406 out:
407 mutex_unlock(&devices_lock);
408 return retval;
409 }
410
411 static const struct file_operations roccat_ops = {
412 .owner = THIS_MODULE,
413 .read = roccat_read,
414 .poll = roccat_poll,
415 .open = roccat_open,
416 .release = roccat_release,
417 .llseek = noop_llseek,
418 .unlocked_ioctl = roccat_ioctl,
419 };
420
roccat_init(void)421 static int __init roccat_init(void)
422 {
423 int retval;
424 dev_t dev_id;
425
426 retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
427 ROCCAT_MAX_DEVICES, "roccat");
428 if (retval < 0) {
429 pr_warn("can't get major number\n");
430 goto error;
431 }
432
433 roccat_major = MAJOR(dev_id);
434
435 cdev_init(&roccat_cdev, &roccat_ops);
436 retval = cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
437
438 if (retval < 0) {
439 pr_warn("cannot add cdev\n");
440 goto cleanup_alloc_chrdev_region;
441 }
442 return 0;
443
444
445 cleanup_alloc_chrdev_region:
446 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
447 error:
448 return retval;
449 }
450
roccat_exit(void)451 static void __exit roccat_exit(void)
452 {
453 dev_t dev_id = MKDEV(roccat_major, 0);
454
455 cdev_del(&roccat_cdev);
456 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
457 }
458
459 module_init(roccat_init);
460 module_exit(roccat_exit);
461
462 MODULE_AUTHOR("Stefan Achatz");
463 MODULE_DESCRIPTION("USB Roccat char device");
464 MODULE_LICENSE("GPL v2");
465