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 #include <linux/cdev.h>
  25 #include <linux/poll.h>
  26 #include <linux/sched.h>
  27
  28 #include "hid-roccat.h"
  29
  30 #define ROCCAT_FIRST_MINOR 0
  31 #define ROCCAT_MAX_DEVICES 8
  32
  33 /* should be a power of 2 for performance reason */
  34 #define ROCCAT_CBUF_SIZE 16
  35
  36 struct roccat_report {
  37         uint8_t *value;
  38         int len;
  39 };
  40
  41 struct roccat_device {
  42         unsigned int minor;
  43         int open;
  44         int exist;
  45         wait_queue_head_t wait;
  46         struct device *dev;
  47         struct hid_device *hid;
  48         struct list_head readers;
  49         /* protects modifications of readers list */
  50         struct mutex readers_lock;
  51
  52         /*
  53          * circular_buffer has one writer and multiple readers with their own
  54          * read pointers
  55          */
  56         struct roccat_report cbuf[ROCCAT_CBUF_SIZE];
  57         int cbuf_end;
  58         struct mutex cbuf_lock;
  59 };
  60
  61 struct roccat_reader {
  62         struct list_head node;
  63         struct roccat_device *device;
  64         int cbuf_start;
  65 };
  66
  67 static int roccat_major;
  68 static struct class *roccat_class;
  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 = report->len > count ? count : report->len;
 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                 printk(KERN_EMERG "roccat device with minor %d doesn't exist\n",
 169                                 minor);
 170                 error = -ENODEV;
 171                 goto exit_err;
 172         }
 173
 174         if (!device->open++) {
 175                 /* power on device on adding first reader */
 176                 if (device->hid->ll_driver->power) {
 177                         error = device->hid->ll_driver->power(device->hid,
 178                                         PM_HINT_FULLON);
 179                         if (error < 0) {
 180                                 --device->open;
 181                                 goto exit_err;
 182                         }
 183                 }
 184                 error = device->hid->ll_driver->open(device->hid);
 185                 if (error < 0) {
 186                         if (device->hid->ll_driver->power)
 187                                 device->hid->ll_driver->power(device->hid,
 188                                                 PM_HINT_NORMAL);
 189                         --device->open;
 190                         goto exit_err;
 191                 }
 192         }
 193
 194         reader->device = device;
 195         /* new reader doesn't get old events */
 196         reader->cbuf_start = device->cbuf_end;
 197
 198         list_add_tail(&reader->node, &device->readers);
 199         file->private_data = reader;
 200
 201 exit_unlock:
 202         mutex_unlock(&device->readers_lock);
 203         mutex_unlock(&devices_lock);
 204         return error;
 205 exit_err:
 206         kfree(reader);
 207         goto exit_unlock;
 208 }
 209
 210 static int roccat_release(struct inode *inode, struct file *file)
 211 {
 212         unsigned int minor = iminor(inode);
 213         struct roccat_reader *reader = file->private_data;
 214         struct roccat_device *device;
 215
 216         mutex_lock(&devices_lock);
 217
 218         device = devices[minor];
 219         if (!device) {
 220                 mutex_unlock(&devices_lock);
 221                 printk(KERN_EMERG "roccat device with minor %d doesn't exist\n",
 222                                 minor);
 223                 return -ENODEV;
 224         }
 225
 226         mutex_lock(&device->readers_lock);
 227         list_del(&reader->node);
 228         mutex_unlock(&device->readers_lock);
 229         kfree(reader);
 230
 231         if (!--device->open) {
 232                 /* removing last reader */
 233                 if (device->exist) {
 234                         if (device->hid->ll_driver->power)
 235                                 device->hid->ll_driver->power(device->hid,
 236                                                 PM_HINT_NORMAL);
 237                         device->hid->ll_driver->close(device->hid);
 238                 } else {
 239                         kfree(device);
 240                 }
 241         }
 242
 243         mutex_unlock(&devices_lock);
 244
 245         return 0;
 246 }
 247
 248 /*
 249  * roccat_report_event() - output data to readers
 250  * @minor: minor device number returned by roccat_connect()
 251  * @data: pointer to data
 252  * @len: size of data
 253  *
 254  * Return value is zero on success, a negative error code on failure.
 255  *
 256  * This is called from interrupt handler.
 257  */
 258 int roccat_report_event(int minor, u8 const *data, int len)
 259 {
 260         struct roccat_device *device;
 261         struct roccat_reader *reader;
 262         struct roccat_report *report;
 263         uint8_t *new_value;
 264
 265         new_value = kmemdup(data, len, GFP_ATOMIC);
 266         if (!new_value)
 267                 return -ENOMEM;
 268
 269         device = devices[minor];
 270
 271         report = &device->cbuf[device->cbuf_end];
 272
 273         /* passing NULL is safe */
 274         kfree(report->value);
 275
 276         report->value = new_value;
 277         report->len = len;
 278         device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
 279
 280         list_for_each_entry(reader, &device->readers, node) {
 281                 /*
 282                  * As we already inserted one element, the buffer can't be
 283                  * empty. If start and end are equal, buffer is full and we
 284                  * increase start, so that slow reader misses one event, but
 285                  * gets the newer ones in the right order.
 286                  */
 287                 if (reader->cbuf_start == device->cbuf_end)
 288                         reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
 289         }
 290
 291         wake_up_interruptible(&device->wait);
 292         return 0;
 293 }
 294 EXPORT_SYMBOL_GPL(roccat_report_event);
 295
 296 /*
 297  * roccat_connect() - create a char device for special event output
 298  * @hid: the hid device the char device should be connected to.
 299  *
 300  * Return value is minor device number in Range [0, ROCCAT_MAX_DEVICES] on
 301  * success, a negative error code on failure.
 302  */
 303 int roccat_connect(struct hid_device *hid)
 304 {
 305         unsigned int minor;
 306         struct roccat_device *device;
 307         int temp;
 308
 309         device = kzalloc(sizeof(struct roccat_device), GFP_KERNEL);
 310         if (!device)
 311                 return -ENOMEM;
 312
 313         mutex_lock(&devices_lock);
 314
 315         for (minor = 0; minor < ROCCAT_MAX_DEVICES; ++minor) {
 316                 if (devices[minor])
 317                         continue;
 318                 break;
 319         }
 320
 321         if (minor < ROCCAT_MAX_DEVICES) {
 322                 devices[minor] = device;
 323         } else {
 324                 mutex_unlock(&devices_lock);
 325                 kfree(device);
 326                 return -EINVAL;
 327         }
 328
 329         device->dev = device_create(roccat_class, &hid->dev,
 330                         MKDEV(roccat_major, minor), NULL,
 331                         "%s%s%d", "roccat", hid->driver->name, minor);
 332
 333         if (IS_ERR(device->dev)) {
 334                 devices[minor] = NULL;
 335                 mutex_unlock(&devices_lock);
 336                 temp = PTR_ERR(device->dev);
 337                 kfree(device);
 338                 return temp;
 339         }
 340
 341         mutex_unlock(&devices_lock);
 342
 343         init_waitqueue_head(&device->wait);
 344         INIT_LIST_HEAD(&device->readers);
 345         mutex_init(&device->readers_lock);
 346         mutex_init(&device->cbuf_lock);
 347         device->minor = minor;
 348         device->hid = hid;
 349         device->exist = 1;
 350         device->cbuf_end = 0;
 351
 352         return minor;
 353 }
 354 EXPORT_SYMBOL_GPL(roccat_connect);
 355
 356 /* roccat_disconnect() - remove char device from hid device
 357  * @minor: the minor device number returned by roccat_connect()
 358  */
 359 void roccat_disconnect(int minor)
 360 {
 361         struct roccat_device *device;
 362
 363         mutex_lock(&devices_lock);
 364         device = devices[minor];
 365         devices[minor] = NULL;
 366         mutex_unlock(&devices_lock);
 367
 368         device->exist = 0; /* TODO exist maybe not needed */
 369
 370         device_destroy(roccat_class, MKDEV(roccat_major, minor));
 371
 372         if (device->open) {
 373                 device->hid->ll_driver->close(device->hid);
 374                 wake_up_interruptible(&device->wait);
 375         } else {
 376                 kfree(device);
 377         }
 378 }
 379 EXPORT_SYMBOL_GPL(roccat_disconnect);
 380
 381 static const struct file_operations roccat_ops = {
 382         .owner = THIS_MODULE,
 383         .read = roccat_read,
 384         .poll = roccat_poll,
 385         .open = roccat_open,
 386         .release = roccat_release,
 387 };
 388
 389 static int __init roccat_init(void)
 390 {
 391         int retval;
 392         dev_t dev_id;
 393
 394         retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
 395                         ROCCAT_MAX_DEVICES, "roccat");
 396
 397         roccat_major = MAJOR(dev_id);
 398
 399         if (retval < 0) {
 400                 printk(KERN_WARNING "roccat: can't get major number\n");
 401                 return retval;
 402         }
 403
 404         roccat_class = class_create(THIS_MODULE, "roccat");
 405         if (IS_ERR(roccat_class)) {
 406                 retval = PTR_ERR(roccat_class);
 407                 unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
 408                 return retval;
 409         }
 410
 411         cdev_init(&roccat_cdev, &roccat_ops);
 412         cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
 413
 414         return 0;
 415 }
 416
 417 static void __exit roccat_exit(void)
 418 {
 419         dev_t dev_id = MKDEV(roccat_major, 0);
 420
 421         cdev_del(&roccat_cdev);
 422         class_destroy(roccat_class);
 423         unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
 424 }
 425
 426 module_init(roccat_init);
 427 module_exit(roccat_exit);
 428
 429 MODULE_AUTHOR("Stefan Achatz");
 430 MODULE_DESCRIPTION("USB Roccat char device");
 431 MODULE_LICENSE("GPL v2");