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 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 } 136 137 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 } 147 148 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 } 202 203 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 */ 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 */ 298 int roccat_connect(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 */ 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); 379 380 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 }; 417 418 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 } 447 448 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