drivers/hid/hid-roccat.c

   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
  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
 140 static unsigned int 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 POLLIN | POLLRDNORM;
 146         if (!reader->device->exist)
 147                 return POLLERR | POLLHUP;
 148         return 0;
 149 }
 150
 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
 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  */
 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         report = &device->cbuf[device->cbuf_end];
 264
 265         /* passing NULL is safe */
 266         kfree(report->value);
 267
 268         report->value = new_value;
 269         device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
 270
 271         list_for_each_entry(reader, &device->readers, node) {
 272                 /*
 273                  * As we already inserted one element, the buffer can't be
 274                  * empty. If start and end are equal, buffer is full and we
 275                  * increase start, so that slow reader misses one event, but
 276                  * gets the newer ones in the right order.
 277                  */
 278                 if (reader->cbuf_start == device->cbuf_end)
 279                         reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
 280         }
 281
 282         wake_up_interruptible(&device->wait);
 283         return 0;
 284 }
 285 EXPORT_SYMBOL_GPL(roccat_report_event);
 286
 287 /*
 288  * roccat_connect() - create a char device for special event output
 289  * @class: the class thats used to create the device. Meant to hold device
 290  * specific sysfs attributes.
 291  * @hid: the hid device the char device should be connected to.
 292  * @report_size: size of reports
 293  *
 294  * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
 295  * success, a negative error code on failure.
 296  */
 297 int roccat_connect(struct class *klass, struct hid_device *hid, int report_size)
 298 {
 299         unsigned int minor;
 300         struct roccat_device *device;
 301         int temp;
 302
 303         device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
 304         if (!device)
 305                 return -ENOMEM;
 306
 307         mutex_lock(&devices_lock);
 308
 309         for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
 310                 if (devices[minor])
 311                         continue;
 312                 break;
 313         }
 314
 315         if (minor < ROCCAT_MAX_DEVICES) {
 316                 devices[minor] = device;
 317         } else {
 318                 mutex_unlock(&devices_lock);
 319                 kfree(device);
 320                 return -EINVAL;
 321         }
 322
 323         device->dev = device_create(klass, &hid->dev,
 324                         MKDEV(roccat_major, minor), NULL,
 325                         "%s%s%d", "roccat", hid->driver->name, minor);
 326
 327         if (IS_ERR(device->dev)) {
 328                 devices[minor] = NULL;
 329                 mutex_unlock(&devices_lock);
 330                 temp = PTR_ERR(device->dev);
 331                 kfree(device);
 332                 return temp;
 333         }
 334
 335         mutex_unlock(&devices_lock);
 336
 337         init_waitqueue_head(&device->wait);
 338         INIT_LIST_HEAD(&device->readers);
 339         mutex_init(&device->readers_lock);
 340         mutex_init(&device->cbuf_lock);
 341         device->minor = minor;
 342         device->hid = hid;
 343         device->exist = 1;
 344         device->cbuf_end = 0;
 345         device->report_size = report_size;
 346
 347         return minor;
 348 }
 349 EXPORT_SYMBOL_GPL(roccat_connect);
 350
 351 /* roccat_disconnect() - remove char device from hid device
 352  * @minor: the minor device number returned by roccat_connect()
 353  */
 354 void roccat_disconnect(int minor)
 355 {
 356         struct roccat_device *device;
 357
 358         mutex_lock(&devices_lock);
 359         device = devices[minor];
 360         mutex_unlock(&devices_lock);
 361
 362         device->exist = 0; /* TODO exist maybe not needed */
 363
 364         device_destroy(device->dev->class, MKDEV(roccat_major, minor));
 365
 366         mutex_lock(&devices_lock);
 367         devices[minor] = NULL;
 368         mutex_unlock(&devices_lock);
 369
 370         if (device->open) {
 371                 hid_hw_close(device->hid);
 372                 wake_up_interruptible(&device->wait);
 373         } else {
 374                 kfree(device);
 375         }
 376 }
 377 EXPORT_SYMBOL_GPL(roccat_disconnect);
 378
 379 static long roccat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 380 {
 381         struct inode *inode = file_inode(file);
 382         struct roccat_device *device;
 383         unsigned int minor = iminor(inode);
 384         long retval = 0;
 385
 386         mutex_lock(&devices_lock);
 387
 388         device = devices[minor];
 389         if (!device) {
 390                 retval = -ENODEV;
 391                 goto out;
 392         }
 393
 394         switch (cmd) {
 395         case ROCCATIOCGREPSIZE:
 396                 if (put_user(device->report_size, (int __user *)arg))
 397                         retval = -EFAULT;
 398                 break;
 399         default:
 400                 retval = -ENOTTY;
 401         }
 402 out:
 403         mutex_unlock(&devices_lock);
 404         return retval;
 405 }
 406
 407 static const struct file_operations roccat_ops = {
 408         .owner = THIS_MODULE,
 409         .read = roccat_read,
 410         .poll = roccat_poll,
 411         .open = roccat_open,
 412         .release = roccat_release,
 413         .llseek = noop_llseek,
 414         .unlocked_ioctl = roccat_ioctl,
 415 };
 416
 417 static int __init roccat_init(void)
 418 {
 419         int retval;
 420         dev_t dev_id;
 421
 422         retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
 423                         ROCCAT_MAX_DEVICES, "roccat");
 424         if (retval < 0) {
 425                 pr_warn("can't get major number\n");
 426                 goto error;
 427         }
 428
 429         roccat_major = MAJOR(dev_id);
 430
 431         cdev_init(&roccat_cdev, &roccat_ops);
 432         retval = cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
 433
 434         if (retval < 0) {
 435                 pr_warn("cannot add cdev\n");
 436                 goto cleanup_alloc_chrdev_region;
 437         }
 438         return 0;
 439
 440
 441  cleanup_alloc_chrdev_region:
 442         unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
 443  error:
 444         return retval;
 445 }
 446
 447 static void __exit roccat_exit(void)
 448 {
 449         dev_t dev_id = MKDEV(roccat_major, 0);
 450
 451         cdev_del(&roccat_cdev);
 452         unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
 453 }
 454
 455 module_init(roccat_init);
 456 module_exit(roccat_exit);
 457
 458 MODULE_AUTHOR("Stefan Achatz");
 459 MODULE_DESCRIPTION("USB Roccat char device");
 460 MODULE_LICENSE("GPL v2");