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