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
  30 #include "hid-roccat.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         int len;
  41 };
  42
  43 struct roccat_device {
  44         unsigned int minor;
  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 = report->len > count ? count : report->len;
 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         mutex_lock(&device->readers_lock);
 167
 168         if (!device) {
 169                 pr_emerg("roccat device with minor %d doesn't exist\n", minor);
 170                 error = -ENODEV;
 171                 goto exit_err;
 172         }
 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;
 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;
 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_unlock:
 198         mutex_unlock(&device->readers_lock);
 199         mutex_unlock(&devices_lock);
 200         return error;
 201 exit_err:
 202         kfree(reader);
 203         goto exit_unlock;
 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  * @len: size of data
 246  *
 247  * Return value is zero on success, a negative error code on failure.
 248  *
 249  * This is called from interrupt handler.
 250  */
 251 int roccat_report_event(int minor, u8 const *data, int len)
 252 {
 253         struct roccat_device *device;
 254         struct roccat_reader *reader;
 255         struct roccat_report *report;
 256         uint8_t *new_value;
 257
 258         new_value = kmemdup(data, len, GFP_ATOMIC);
 259         if (!new_value)
 260                 return -ENOMEM;
 261
 262         device = devices[minor];
 263
 264         report = &device->cbuf[device->cbuf_end];
 265
 266         /* passing NULL is safe */
 267         kfree(report->value);
 268
 269         report->value = new_value;
 270         report->len = len;
 271         device->cbuf_end = (device->cbuf_end + 1) % ROCCAT_CBUF_SIZE;
 272
 273         list_for_each_entry(reader, &device->readers, node) {
 274                 /*
 275                  * As we already inserted one element, the buffer can't be
 276                  * empty. If start and end are equal, buffer is full and we
 277                  * increase start, so that slow reader misses one event, but
 278                  * gets the newer ones in the right order.
 279                  */
 280                 if (reader->cbuf_start == device->cbuf_end)
 281                         reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE;
 282         }
 283
 284         wake_up_interruptible(&device->wait);
 285         return 0;
 286 }
 287 EXPORT_SYMBOL_GPL(roccat_report_event);
 288
 289 /*
 290  * roccat_connect() - create a char device for special event output
 291  * @class: the class thats used to create the device. Meant to hold device
 292  * specific sysfs attributes.
 293  * @hid: the hid device the char device should be connected to.
 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)
 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
 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         devices[minor] = NULL;
 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         if (device->open) {
 368                 hid_hw_close(device->hid);
 369                 wake_up_interruptible(&device->wait);
 370         } else {
 371                 kfree(device);
 372         }
 373 }
 374 EXPORT_SYMBOL_GPL(roccat_disconnect);
 375
 376 static const struct file_operations roccat_ops = {
 377         .owner = THIS_MODULE,
 378         .read = roccat_read,
 379         .poll = roccat_poll,
 380         .open = roccat_open,
 381         .release = roccat_release,
 382         .llseek = noop_llseek,
 383 };
 384
 385 static int __init roccat_init(void)
 386 {
 387         int retval;
 388         dev_t dev_id;
 389
 390         retval = alloc_chrdev_region(&dev_id, ROCCAT_FIRST_MINOR,
 391                         ROCCAT_MAX_DEVICES, "roccat");
 392
 393         roccat_major = MAJOR(dev_id);
 394
 395         if (retval < 0) {
 396                 pr_warn("can't get major number\n");
 397                 return retval;
 398         }
 399
 400         cdev_init(&roccat_cdev, &roccat_ops);
 401         cdev_add(&roccat_cdev, dev_id, ROCCAT_MAX_DEVICES);
 402
 403         return 0;
 404 }
 405
 406 static void __exit roccat_exit(void)
 407 {
 408         dev_t dev_id = MKDEV(roccat_major, 0);
 409
 410         cdev_del(&roccat_cdev);
 411         unregister_chrdev_region(dev_id, ROCCAT_MAX_DEVICES);
 412 }
 413
 414 module_init(roccat_init);
 415 module_exit(roccat_exit);
 416
 417 MODULE_AUTHOR("Stefan Achatz");
 418 MODULE_DESCRIPTION("USB Roccat char device");
 419 MODULE_LICENSE("GPL v2");