drivers/hid/hid-roccat.c

   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(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  */
 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");