1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Roccat driver for Linux
4 *
5 * Copyright (c) 2010 Stefan Achatz <erazor_de@users.sourceforge.net>
6 */
7
8 /*
9 */
10
11 /*
12 * Module roccat is a char device used to report special events of roccat
13 * hardware to userland. These events include requests for on-screen-display of
14 * profile or dpi settings or requests for execution of macro sequences that are
15 * not stored in device. The information in these events depends on hid device
16 * implementation and contains data that is not available in a single hid event
17 * or else hidraw could have been used.
18 * It is inspired by hidraw, but uses only one circular buffer for all readers.
19 */
20
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22
23 #include <linux/cdev.h>
24 #include <linux/poll.h>
25 #include <linux/sched/signal.h>
26 #include <linux/hid-roccat.h>
27 #include <linux/module.h>
28
29 #define ROCCAT_FIRST_MINOR 0
30 #define ROCCAT_MAX_DEVICES 8
31
32 /* should be a power of 2 for performance reason */
33 #define ROCCAT_CBUF_SIZE 16
34
35 struct roccat_report {
36 uint8_t *value;
37 };
38
39 struct roccat_device {
40 unsigned int minor;
41 int report_size;
42 int open;
43 int exist;
44 wait_queue_head_t wait;
45 struct device *dev;
46 struct hid_device *hid;
47 struct list_head readers;
48 /* protects modifications of readers list */
49 struct mutex readers_lock;
50
51 /*
52 * circular_buffer has one writer and multiple readers with their own
53 * read pointers
54 */
55 struct roccat_report cbuf[ROCCAT_CBUF_SIZE];
56 int cbuf_end;
57 struct mutex cbuf_lock;
58 };
59
60 struct roccat_reader {
61 struct list_head node;
62 struct roccat_device *device;
63 int cbuf_start;
64 };
65
66 static int roccat_major;
67 static struct cdev roccat_cdev;
68
69 static struct roccat_device *devices[ROCCAT_MAX_DEVICES];
70 /* protects modifications of devices array */
71 static DEFINE_MUTEX(devices_lock);
72
roccat_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)73 static ssize_t roccat_read(struct file *file, char __user *buffer,
74 size_t count, loff_t *ppos)
75 {
76 struct roccat_reader *reader = file->private_data;
77 struct roccat_device *device = reader->device;
78 struct roccat_report *report;
79 ssize_t retval = 0, len;
80 DECLARE_WAITQUEUE(wait, current);
81
82 mutex_lock(&device->cbuf_lock);
83
84 /* no data? */
85 if (reader->cbuf_start == device->cbuf_end) {
86 add_wait_queue(&device->wait, &wait);
87 set_current_state(TASK_INTERRUPTIBLE);
88
89 /* wait for data */
90 while (reader->cbuf_start == device->cbuf_end) {
91 if (file->f_flags & O_NONBLOCK) {
92 retval = -EAGAIN;
93 break;
94 }
95 if (signal_pending(current)) {
96 retval = -ERESTARTSYS;
97 break;
98 }
99 if (!device->exist) {
100 retval = -EIO;
101 break;
102 }
103
104 mutex_unlock(&device->cbuf_lock);
105 schedule();
106 mutex_lock(&device->cbuf_lock);
107 set_current_state(TASK_INTERRUPTIBLE);
108 }
109
110 set_current_state(TASK_RUNNING);
111 remove_wait_queue(&device->wait, &wait);
112 }
113
114 /* here we either have data or a reason to return if retval is set */
115 if (retval)
116 goto exit_unlock;
117
118 report = &device->cbuf[reader->cbuf_start];
119 /*
120 * If report is larger than requested amount of data, rest of report
121 * is lost!
122 */
123 len = device->report_size > count ? count : device->report_size;
124
125 if (copy_to_user(buffer, report->value, len)) {
126 retval = -EFAULT;
127 goto exit_unlock;
128 }
129 retval += len;
130 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
131
132 exit_unlock:
133 mutex_unlock(&device->cbuf_lock);
134 return retval;
135 }
136
roccat_poll(struct file * file,poll_table * wait)137 static __poll_t roccat_poll(struct file *file, poll_table *wait)
138 {
139 struct roccat_reader *reader = file->private_data;
140 poll_wait(file, &reader->device->wait, wait);
141 if (reader->cbuf_start != reader->device->cbuf_end)
142 return EPOLLIN | EPOLLRDNORM;
143 if (!reader->device->exist)
144 return EPOLLERR | EPOLLHUP;
145 return 0;
146 }
147
roccat_open(struct inode * inode,struct file * file)148 static int roccat_open(struct inode *inode, struct file *file)
149 {
150 unsigned int minor = iminor(inode);
151 struct roccat_reader *reader;
152 struct roccat_device *device;
153 int error = 0;
154
155 reader = kzalloc(sizeof(struct roccat_reader), GFP_KERNEL);
156 if (!reader)
157 return -ENOMEM;
158
159 mutex_lock(&devices_lock);
160
161 device = devices[minor];
162
163 if (!device) {
164 pr_emerg("roccat device with minor %d doesn't exist\n", minor);
165 error = -ENODEV;
166 goto exit_err_devices;
167 }
168
169 mutex_lock(&device->readers_lock);
170
171 if (!device->open++) {
172 /* power on device on adding first reader */
173 error = hid_hw_power(device->hid, PM_HINT_FULLON);
174 if (error < 0) {
175 --device->open;
176 goto exit_err_readers;
177 }
178
179 error = hid_hw_open(device->hid);
180 if (error < 0) {
181 hid_hw_power(device->hid, PM_HINT_NORMAL);
182 --device->open;
183 goto exit_err_readers;
184 }
185 }
186
187 reader->device = device;
188 /* new reader doesn't get old events */
189 reader->cbuf_start = device->cbuf_end;
190
191 list_add_tail(&reader->node, &device->readers);
192 file->private_data = reader;
193
194 exit_err_readers:
195 mutex_unlock(&device->readers_lock);
196 exit_err_devices:
197 mutex_unlock(&devices_lock);
198 if (error)
199 kfree(reader);
200 return error;
201 }
202
roccat_release(struct inode * inode,struct file * file)203 static int roccat_release(struct inode *inode, struct file *file)
204 {
205 unsigned int minor = iminor(inode);
206 struct roccat_reader *reader = file->private_data;
207 struct roccat_device *device;
208
209 mutex_lock(&devices_lock);
210
211 device = devices[minor];
212 if (!device) {
213 mutex_unlock(&devices_lock);
214 pr_emerg("roccat device with minor %d doesn't exist\n", minor);
215 return -ENODEV;
216 }
217
218 mutex_lock(&device->readers_lock);
219 list_del(&reader->node);
220 mutex_unlock(&device->readers_lock);
221 kfree(reader);
222
223 if (!--device->open) {
224 /* removing last reader */
225 if (device->exist) {
226 hid_hw_power(device->hid, PM_HINT_NORMAL);
227 hid_hw_close(device->hid);
228 } else {
229 kfree(device);
230 }
231 }
232
233 mutex_unlock(&devices_lock);
234
235 return 0;
236 }
237
238 /*
239 * roccat_report_event() - output data to readers
240 * @minor: minor device number returned by roccat_connect()
241 * @data: pointer to data
242 *
243 * Return value is zero on success, a negative error code on failure.
244 *
245 * This is called from interrupt handler.
246 */
roccat_report_event(int minor,u8 const * data)247 int roccat_report_event(int minor, u8 const *data)
248 {
249 struct roccat_device *device;
250 struct roccat_reader *reader;
251 struct roccat_report *report;
252 uint8_t *new_value;
253
254 device = devices[minor];
255
256 new_value = kmemdup(data, device->report_size, GFP_ATOMIC);
257 if (!new_value)
258 return -ENOMEM;
259
260 mutex_lock(&device->cbuf_lock);
261
262 report = &device->cbuf[device->cbuf_end];
263
264 /* passing NULL is safe */
265 kfree(report->value);
266
267 report->value = new_value;
268 device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
269
270 list_for_each_entry(reader, &device->readers, node) {
271 /*
272 * As we already inserted one element, the buffer can't be
273 * empty. If start and end are equal, buffer is full and we
274 * increase start, so that slow reader misses one event, but
275 * gets the newer ones in the right order.
276 */
277 if (reader->cbuf_start == device->cbuf_end)
278 reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
279 }
280
281 mutex_unlock(&device->cbuf_lock);
282
283 wake_up_interruptible(&device->wait);
284 return 0;
285 }
286 EXPORT_SYMBOL_GPL(roccat_report_event);
287
288 /*
289 * roccat_connect() - create a char device for special event output
290 * @class: the class thats used to create the device. Meant to hold device
291 * specific sysfs attributes.
292 * @hid: the hid device the char device should be connected to.
293 * @report_size: size of reports
294 *
295 * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
296 * success, a negative error code on failure.
297 */
roccat_connect(const struct class * klass,struct hid_device * hid,int report_size)298 int roccat_connect(const struct class *klass, struct hid_device *hid, int report_size)
299 {
300 unsigned int minor;
301 struct roccat_device *device;
302 int temp;
303
304 device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
305 if (!device)
306 return -ENOMEM;
307
308 mutex_lock(&devices_lock);
309
310 for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
311 if (devices[minor])
312 continue;
313 break;
314 }
315
316 if (minor < ROCCAT_MAX_DEVICES) {
317 devices[minor] = device;
318 } else {
319 mutex_unlock(&devices_lock);
320 kfree(device);
321 return -EINVAL;
322 }
323
324 device->dev = device_create(klass, &hid->dev,
325 MKDEV(roccat_major, minor), NULL,
326 "%s%s%d", "roccat", hid->driver->name, minor);
327
328 if (IS_ERR(device->dev)) {
329 devices[minor] = NULL;
330 mutex_unlock(&devices_lock);
331 temp = PTR_ERR(device->dev);
332 kfree(device);
333 return temp;
334 }
335
336 mutex_unlock(&devices_lock);
337
338 init_waitqueue_head(&device->wait);
339 INIT_LIST_HEAD(&device->readers);
340 mutex_init(&device->readers_lock);
341 mutex_init(&device->cbuf_lock);
342 device->minor = minor;
343 device->hid = hid;
344 device->exist = 1;
345 device->cbuf_end = 0;
346 device->report_size = report_size;
347
348 return minor;
349 }
350 EXPORT_SYMBOL_GPL(roccat_connect);
351
352 /* roccat_disconnect() - remove char device from hid device
353 * @minor: the minor device number returned by roccat_connect()
354 */
roccat_disconnect(int minor)355 void roccat_disconnect(int minor)
356 {
357 struct roccat_device *device;
358
359 mutex_lock(&devices_lock);
360 device = devices[minor];
361 mutex_unlock(&devices_lock);
362
363 device->exist = 0; /* TODO exist maybe not needed */
364
365 device_destroy(device->dev->class, MKDEV(roccat_major, minor));
366
367 mutex_lock(&devices_lock);
368 devices[minor] = NULL;
369 mutex_unlock(&devices_lock);
370
371 if (device->open) {
372 hid_hw_close(device->hid);
373 wake_up_interruptible(&device->wait);
374 } else {
375 kfree(device);
376 }
377 }
378 EXPORT_SYMBOL_GPL(roccat_disconnect);
379
roccat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)380 static long roccat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
381 {
382 struct inode *inode = file_inode(file);
383 struct roccat_device *device;
384 unsigned int minor = iminor(inode);
385 long retval = 0;
386
387 mutex_lock(&devices_lock);
388
389 device = devices[minor];
390 if (!device) {
391 retval = -ENODEV;
392 goto out;
393 }
394
395 switch (cmd) {
396 case ROCCATIOCGREPSIZE:
397 if (put_user(device->report_size, (int __user *)arg))
398 retval = -EFAULT;
399 break;
400 default:
401 retval = -ENOTTY;
402 }
403 out:
404 mutex_unlock(&devices_lock);
405 return retval;
406 }
407
408 static const struct file_operations roccat_ops = {
409 .owner = THIS_MODULE,
410 .read = roccat_read,
411 .poll = roccat_poll,
412 .open = roccat_open,
413 .release = roccat_release,
414 .llseek = noop_llseek,
415 .unlocked_ioctl = roccat_ioctl,
416 };
417
roccat_init(void)418 static int __init roccat_init(void)
419 {
420 int retval;
421 dev_t dev_id;
422
423 retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
424 ROCCAT_MAX_DEVICES, "roccat");
425 if (retval < 0) {
426 pr_warn("can't get major number\n");
427 goto error;
428 }
429
430 roccat_major = MAJOR(dev_id);
431
432 cdev_init(&roccat_cdev, &roccat_ops);
433 retval = cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
434
435 if (retval < 0) {
436 pr_warn("cannot add cdev\n");
437 goto cleanup_alloc_chrdev_region;
438 }
439 return 0;
440
441
442 cleanup_alloc_chrdev_region:
443 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
444 error:
445 return retval;
446 }
447
roccat_exit(void)448 static void __exit roccat_exit(void)
449 {
450 dev_t dev_id = MKDEV(roccat_major, 0);
451
452 cdev_del(&roccat_cdev);
453 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
454 }
455
456 module_init(roccat_init);
457 module_exit(roccat_exit);
458
459 MODULE_AUTHOR("Stefan Achatz");
460 MODULE_DESCRIPTION("USB Roccat char device");
461 MODULE_LICENSE("GPL v2");
462
