drivers/usb/gadget/f_hid.c

   1 /*
   2  * f_hid.c -- USB HID function driver
   3  *
   4  * Copyright (C) 2010 Fabien Chouteau <fabien.chouteau@barco.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/utsname.h>
  23 #include <linux/module.h>
  24 #include <linux/hid.h>
  25 #include <linux/cdev.h>
  26 #include <linux/mutex.h>
  27 #include <linux/poll.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/wait.h>
  30 #include <linux/usb/g_hid.h>
  31
  32 static int major, minors;
  33 static struct class *hidg_class;
  34
  35 /*-------------------------------------------------------------------------*/
  36 /*                            HID gadget struct                            */
  37
  38 struct f_hidg {
  39         /* configuration */
  40         unsigned char                   bInterfaceSubClass;
  41         unsigned char                   bInterfaceProtocol;
  42         unsigned short                  report_desc_length;
  43         char                            *report_desc;
  44         unsigned short                  report_length;
  45
  46         /* recv report */
  47         char                            *set_report_buff;
  48         unsigned short                  set_report_length;
  49         spinlock_t                      spinlock;
  50         wait_queue_head_t               read_queue;
  51
  52         /* send report */
  53         struct mutex                    lock;
  54         bool                            write_pending;
  55         wait_queue_head_t               write_queue;
  56         struct usb_request              *req;
  57
  58         int                             minor;
  59         struct cdev                     cdev;
  60         struct usb_function             func;
  61         struct usb_ep                   *in_ep;
  62 };
  63
  64 static inline struct f_hidg *func_to_hidg(struct usb_function *f)
  65 {
  66         return container_of(f, struct f_hidg, func);
  67 }
  68
  69 /*-------------------------------------------------------------------------*/
  70 /*                           Static descriptors                            */
  71
  72 static struct usb_interface_descriptor hidg_interface_desc = {
  73         .bLength                = sizeof hidg_interface_desc,
  74         .bDescriptorType        = USB_DT_INTERFACE,
  75         /* .bInterfaceNumber    = DYNAMIC */
  76         .bAlternateSetting      = 0,
  77         .bNumEndpoints          = 1,
  78         .bInterfaceClass        = USB_CLASS_HID,
  79         /* .bInterfaceSubClass  = DYNAMIC */
  80         /* .bInterfaceProtocol  = DYNAMIC */
  81         /* .iInterface          = DYNAMIC */
  82 };
  83
  84 static struct hid_descriptor hidg_desc = {
  85         .bLength                        = sizeof hidg_desc,
  86         .bDescriptorType                = HID_DT_HID,
  87         .bcdHID                         = 0x0101,
  88         .bCountryCode                   = 0x00,
  89         .bNumDescriptors                = 0x1,
  90         /*.desc[0].bDescriptorType      = DYNAMIC */
  91         /*.desc[0].wDescriptorLenght    = DYNAMIC */
  92 };
  93
  94 /* High-Speed Support */
  95
  96 static struct usb_endpoint_descriptor hidg_hs_in_ep_desc = {
  97         .bLength                = USB_DT_ENDPOINT_SIZE,
  98         .bDescriptorType        = USB_DT_ENDPOINT,
  99         .bEndpointAddress       = USB_DIR_IN,
 100         .bmAttributes           = USB_ENDPOINT_XFER_INT,
 101         /*.wMaxPacketSize       = DYNAMIC */
 102         .bInterval              = 4, /* FIXME: Add this field in the
 103                                       * HID gadget configuration?
 104                                       * (struct hidg_func_descriptor)
 105                                       */
 106 };
 107
 108 static struct usb_descriptor_header *hidg_hs_descriptors[] = {
 109         (struct usb_descriptor_header *)&hidg_interface_desc,
 110         (struct usb_descriptor_header *)&hidg_desc,
 111         (struct usb_descriptor_header *)&hidg_hs_in_ep_desc,
 112         NULL,
 113 };
 114
 115 /* Full-Speed Support */
 116
 117 static struct usb_endpoint_descriptor hidg_fs_in_ep_desc = {
 118         .bLength                = USB_DT_ENDPOINT_SIZE,
 119         .bDescriptorType        = USB_DT_ENDPOINT,
 120         .bEndpointAddress       = USB_DIR_IN,
 121         .bmAttributes           = USB_ENDPOINT_XFER_INT,
 122         /*.wMaxPacketSize       = DYNAMIC */
 123         .bInterval              = 10, /* FIXME: Add this field in the
 124                                        * HID gadget configuration?
 125                                        * (struct hidg_func_descriptor)
 126                                        */
 127 };
 128
 129 static struct usb_descriptor_header *hidg_fs_descriptors[] = {
 130         (struct usb_descriptor_header *)&hidg_interface_desc,
 131         (struct usb_descriptor_header *)&hidg_desc,
 132         (struct usb_descriptor_header *)&hidg_fs_in_ep_desc,
 133         NULL,
 134 };
 135
 136 /*-------------------------------------------------------------------------*/
 137 /*                              Char Device                                */
 138
 139 static ssize_t f_hidg_read(struct file *file, char __user *buffer,
 140                         size_t count, loff_t *ptr)
 141 {
 142         struct f_hidg   *hidg     = file->private_data;
 143         char            *tmp_buff = NULL;
 144         unsigned long   flags;
 145
 146         if (!count)
 147                 return 0;
 148
 149         if (!access_ok(VERIFY_WRITE, buffer, count))
 150                 return -EFAULT;
 151
 152         spin_lock_irqsave(&hidg->spinlock, flags);
 153
 154 #define READ_COND (hidg->set_report_buff != NULL)
 155
 156         while (!READ_COND) {
 157                 spin_unlock_irqrestore(&hidg->spinlock, flags);
 158                 if (file->f_flags & O_NONBLOCK)
 159                         return -EAGAIN;
 160
 161                 if (wait_event_interruptible(hidg->read_queue, READ_COND))
 162                         return -ERESTARTSYS;
 163
 164                 spin_lock_irqsave(&hidg->spinlock, flags);
 165         }
 166
 167
 168         count = min_t(unsigned, count, hidg->set_report_length);
 169         tmp_buff = hidg->set_report_buff;
 170         hidg->set_report_buff = NULL;
 171
 172         spin_unlock_irqrestore(&hidg->spinlock, flags);
 173
 174         if (tmp_buff != NULL) {
 175                 /* copy to user outside spinlock */
 176                 count -= copy_to_user(buffer, tmp_buff, count);
 177                 kfree(tmp_buff);
 178         } else
 179                 count = -ENOMEM;
 180
 181         return count;
 182 }
 183
 184 static void f_hidg_req_complete(struct usb_ep *ep, struct usb_request *req)
 185 {
 186         struct f_hidg *hidg = (struct f_hidg *)ep->driver_data;
 187
 188         if (req->status != 0) {
 189                 ERROR(hidg->func.config->cdev,
 190                         "End Point Request ERROR: %d\n", req->status);
 191         }
 192
 193         hidg->write_pending = 0;
 194         wake_up(&hidg->write_queue);
 195 }
 196
 197 static ssize_t f_hidg_write(struct file *file, const char __user *buffer,
 198                             size_t count, loff_t *offp)
 199 {
 200         struct f_hidg *hidg  = file->private_data;
 201         ssize_t status = -ENOMEM;
 202
 203         if (!access_ok(VERIFY_READ, buffer, count))
 204                 return -EFAULT;
 205
 206         mutex_lock(&hidg->lock);
 207
 208 #define WRITE_COND (!hidg->write_pending)
 209
 210         /* write queue */
 211         while (!WRITE_COND) {
 212                 mutex_unlock(&hidg->lock);
 213                 if (file->f_flags & O_NONBLOCK)
 214                         return -EAGAIN;
 215
 216                 if (wait_event_interruptible_exclusive(
 217                                 hidg->write_queue, WRITE_COND))
 218                         return -ERESTARTSYS;
 219
 220                 mutex_lock(&hidg->lock);
 221         }
 222
 223         count  = min_t(unsigned, count, hidg->report_length);
 224         status = copy_from_user(hidg->req->buf, buffer, count);
 225
 226         if (status != 0) {
 227                 ERROR(hidg->func.config->cdev,
 228                         "copy_from_user error\n");
 229                 mutex_unlock(&hidg->lock);
 230                 return -EINVAL;
 231         }
 232
 233         hidg->req->status   = 0;
 234         hidg->req->zero     = 0;
 235         hidg->req->length   = count;
 236         hidg->req->complete = f_hidg_req_complete;
 237         hidg->req->context  = hidg;
 238         hidg->write_pending = 1;
 239
 240         status = usb_ep_queue(hidg->in_ep, hidg->req, GFP_ATOMIC);
 241         if (status < 0) {
 242                 ERROR(hidg->func.config->cdev,
 243                         "usb_ep_queue error on int endpoint %zd\n", status);
 244                 hidg->write_pending = 0;
 245                 wake_up(&hidg->write_queue);
 246         } else {
 247                 status = count;
 248         }
 249
 250         mutex_unlock(&hidg->lock);
 251
 252         return status;
 253 }
 254
 255 static unsigned int f_hidg_poll(struct file *file, poll_table *wait)
 256 {
 257         struct f_hidg   *hidg  = file->private_data;
 258         unsigned int    ret = 0;
 259
 260         poll_wait(file, &hidg->read_queue, wait);
 261         poll_wait(file, &hidg->write_queue, wait);
 262
 263         if (WRITE_COND)
 264                 ret |= POLLOUT | POLLWRNORM;
 265
 266         if (READ_COND)
 267                 ret |= POLLIN | POLLRDNORM;
 268
 269         return ret;
 270 }
 271
 272 #undef WRITE_COND
 273 #undef READ_COND
 274
 275 static int f_hidg_release(struct inode *inode, struct file *fd)
 276 {
 277         fd->private_data = NULL;
 278         return 0;
 279 }
 280
 281 static int f_hidg_open(struct inode *inode, struct file *fd)
 282 {
 283         struct f_hidg *hidg =
 284                 container_of(inode->i_cdev, struct f_hidg, cdev);
 285
 286         fd->private_data = hidg;
 287
 288         return 0;
 289 }
 290
 291 /*-------------------------------------------------------------------------*/
 292 /*                                usb_function                             */
 293
 294 static void hidg_set_report_complete(struct usb_ep *ep, struct usb_request *req)
 295 {
 296         struct f_hidg *hidg = (struct f_hidg *)req->context;
 297
 298         if (req->status != 0 || req->buf == NULL || req->actual == 0) {
 299                 ERROR(hidg->func.config->cdev, "%s FAILED\n", __func__);
 300                 return;
 301         }
 302
 303         spin_lock(&hidg->spinlock);
 304
 305         hidg->set_report_buff = krealloc(hidg->set_report_buff,
 306                                          req->actual, GFP_ATOMIC);
 307
 308         if (hidg->set_report_buff == NULL) {
 309                 spin_unlock(&hidg->spinlock);
 310                 return;
 311         }
 312         hidg->set_report_length = req->actual;
 313         memcpy(hidg->set_report_buff, req->buf, req->actual);
 314
 315         spin_unlock(&hidg->spinlock);
 316
 317         wake_up(&hidg->read_queue);
 318 }
 319
 320 static int hidg_setup(struct usb_function *f,
 321                 const struct usb_ctrlrequest *ctrl)
 322 {
 323         struct f_hidg                   *hidg = func_to_hidg(f);
 324         struct usb_composite_dev        *cdev = f->config->cdev;
 325         struct usb_request              *req  = cdev->req;
 326         int status = 0;
 327         __u16 value, length;
 328
 329         value   = __le16_to_cpu(ctrl->wValue);
 330         length  = __le16_to_cpu(ctrl->wLength);
 331
 332         VDBG(cdev, "hid_setup crtl_request : bRequestType:0x%x bRequest:0x%x "
 333                 "Value:0x%x\n", ctrl->bRequestType, ctrl->bRequest, value);
 334
 335         switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
 336         case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
 337                   | HID_REQ_GET_REPORT):
 338                 VDBG(cdev, "get_report\n");
 339
 340                 /* send an empty report */
 341                 length = min_t(unsigned, length, hidg->report_length);
 342                 memset(req->buf, 0x0, length);
 343
 344                 goto respond;
 345                 break;
 346
 347         case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
 348                   | HID_REQ_GET_PROTOCOL):
 349                 VDBG(cdev, "get_protocol\n");
 350                 goto stall;
 351                 break;
 352
 353         case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
 354                   | HID_REQ_SET_REPORT):
 355                 VDBG(cdev, "set_report | wLenght=%d\n", ctrl->wLength);
 356                 req->context  = hidg;
 357                 req->complete = hidg_set_report_complete;
 358                 goto respond;
 359                 break;
 360
 361         case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8
 362                   | HID_REQ_SET_PROTOCOL):
 363                 VDBG(cdev, "set_protocol\n");
 364                 goto stall;
 365                 break;
 366
 367         case ((USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_INTERFACE) << 8
 368                   | USB_REQ_GET_DESCRIPTOR):
 369                 switch (value >> 8) {
 370                 case HID_DT_REPORT:
 371                         VDBG(cdev, "USB_REQ_GET_DESCRIPTOR: REPORT\n");
 372                         length = min_t(unsigned short, length,
 373                                                    hidg->report_desc_length);
 374                         memcpy(req->buf, hidg->report_desc, length);
 375                         goto respond;
 376                         break;
 377
 378                 default:
 379                         VDBG(cdev, "Unknown decriptor request 0x%x\n",
 380                                  value >> 8);
 381                         goto stall;
 382                         break;
 383                 }
 384                 break;
 385
 386         default:
 387                 VDBG(cdev, "Unknown request 0x%x\n",
 388                          ctrl->bRequest);
 389                 goto stall;
 390                 break;
 391         }
 392
 393 stall:
 394         return -EOPNOTSUPP;
 395
 396 respond:
 397         req->zero = 0;
 398         req->length = length;
 399         status = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
 400         if (status < 0)
 401                 ERROR(cdev, "usb_ep_queue error on ep0 %d\n", value);
 402         return status;
 403 }
 404
 405 static void hidg_disable(struct usb_function *f)
 406 {
 407         struct f_hidg *hidg = func_to_hidg(f);
 408
 409         usb_ep_disable(hidg->in_ep);
 410         hidg->in_ep->driver_data = NULL;
 411 }
 412
 413 static int hidg_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 414 {
 415         struct usb_composite_dev                *cdev = f->config->cdev;
 416         struct f_hidg                           *hidg = func_to_hidg(f);
 417         int status = 0;
 418
 419         VDBG(cdev, "hidg_set_alt intf:%d alt:%d\n", intf, alt);
 420
 421         if (hidg->in_ep != NULL) {
 422                 /* restart endpoint */
 423                 if (hidg->in_ep->driver_data != NULL)
 424                         usb_ep_disable(hidg->in_ep);
 425
 426                 status = config_ep_by_speed(f->config->cdev->gadget, f,
 427                                             hidg->in_ep);
 428                 if (status) {
 429                         ERROR(cdev, "config_ep_by_speed FAILED!\n");
 430                         goto fail;
 431                 }
 432                 status = usb_ep_enable(hidg->in_ep);
 433                 if (status < 0) {
 434                         ERROR(cdev, "Enable endpoint FAILED!\n");
 435                         goto fail;
 436                 }
 437                 hidg->in_ep->driver_data = hidg;
 438         }
 439 fail:
 440         return status;
 441 }
 442
 443 const struct file_operations f_hidg_fops = {
 444         .owner          = THIS_MODULE,
 445         .open           = f_hidg_open,
 446         .release        = f_hidg_release,
 447         .write          = f_hidg_write,
 448         .read           = f_hidg_read,
 449         .poll           = f_hidg_poll,
 450         .llseek         = noop_llseek,
 451 };
 452
 453 static int __init hidg_bind(struct usb_configuration *c, struct usb_function *f)
 454 {
 455         struct usb_ep           *ep;
 456         struct f_hidg           *hidg = func_to_hidg(f);
 457         int                     status;
 458         dev_t                   dev;
 459
 460         /* allocate instance-specific interface IDs, and patch descriptors */
 461         status = usb_interface_id(c, f);
 462         if (status < 0)
 463                 goto fail;
 464         hidg_interface_desc.bInterfaceNumber = status;
 465
 466
 467         /* allocate instance-specific endpoints */
 468         status = -ENODEV;
 469         ep = usb_ep_autoconfig(c->cdev->gadget, &hidg_fs_in_ep_desc);
 470         if (!ep)
 471                 goto fail;
 472         ep->driver_data = c->cdev;      /* claim */
 473         hidg->in_ep = ep;
 474
 475         /* preallocate request and buffer */
 476         status = -ENOMEM;
 477         hidg->req = usb_ep_alloc_request(hidg->in_ep, GFP_KERNEL);
 478         if (!hidg->req)
 479                 goto fail;
 480
 481
 482         hidg->req->buf = kmalloc(hidg->report_length, GFP_KERNEL);
 483         if (!hidg->req->buf)
 484                 goto fail;
 485
 486         /* set descriptor dynamic values */
 487         hidg_interface_desc.bInterfaceSubClass = hidg->bInterfaceSubClass;
 488         hidg_interface_desc.bInterfaceProtocol = hidg->bInterfaceProtocol;
 489         hidg_hs_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
 490         hidg_fs_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
 491         hidg_desc.desc[0].bDescriptorType = HID_DT_REPORT;
 492         hidg_desc.desc[0].wDescriptorLength =
 493                 cpu_to_le16(hidg->report_desc_length);
 494
 495         hidg->set_report_buff = NULL;
 496
 497         /* copy descriptors */
 498         f->descriptors = usb_copy_descriptors(hidg_fs_descriptors);
 499         if (!f->descriptors)
 500                 goto fail;
 501
 502         if (gadget_is_dualspeed(c->cdev->gadget)) {
 503                 hidg_hs_in_ep_desc.bEndpointAddress =
 504                         hidg_fs_in_ep_desc.bEndpointAddress;
 505                 f->hs_descriptors = usb_copy_descriptors(hidg_hs_descriptors);
 506                 if (!f->hs_descriptors)
 507                         goto fail;
 508         }
 509
 510         mutex_init(&hidg->lock);
 511         spin_lock_init(&hidg->spinlock);
 512         init_waitqueue_head(&hidg->write_queue);
 513         init_waitqueue_head(&hidg->read_queue);
 514
 515         /* create char device */
 516         cdev_init(&hidg->cdev, &f_hidg_fops);
 517         dev = MKDEV(major, hidg->minor);
 518         status = cdev_add(&hidg->cdev, dev, 1);
 519         if (status)
 520                 goto fail;
 521
 522         device_create(hidg_class, NULL, dev, NULL, "%s%d", "hidg", hidg->minor);
 523
 524         return 0;
 525
 526 fail:
 527         ERROR(f->config->cdev, "hidg_bind FAILED\n");
 528         if (hidg->req != NULL) {
 529                 kfree(hidg->req->buf);
 530                 if (hidg->in_ep != NULL)
 531                         usb_ep_free_request(hidg->in_ep, hidg->req);
 532         }
 533
 534         usb_free_descriptors(f->hs_descriptors);
 535         usb_free_descriptors(f->descriptors);
 536
 537         return status;
 538 }
 539
 540 static void hidg_unbind(struct usb_configuration *c, struct usb_function *f)
 541 {
 542         struct f_hidg *hidg = func_to_hidg(f);
 543
 544         device_destroy(hidg_class, MKDEV(major, hidg->minor));
 545         cdev_del(&hidg->cdev);
 546
 547         /* disable/free request and end point */
 548         usb_ep_disable(hidg->in_ep);
 549         usb_ep_dequeue(hidg->in_ep, hidg->req);
 550         kfree(hidg->req->buf);
 551         usb_ep_free_request(hidg->in_ep, hidg->req);
 552
 553         /* free descriptors copies */
 554         usb_free_descriptors(f->hs_descriptors);
 555         usb_free_descriptors(f->descriptors);
 556
 557         kfree(hidg->report_desc);
 558         kfree(hidg->set_report_buff);
 559         kfree(hidg);
 560 }
 561
 562 /*-------------------------------------------------------------------------*/
 563 /*                                 Strings                                 */
 564
 565 #define CT_FUNC_HID_IDX 0
 566
 567 static struct usb_string ct_func_string_defs[] = {
 568         [CT_FUNC_HID_IDX].s     = "HID Interface",
 569         {},                     /* end of list */
 570 };
 571
 572 static struct usb_gadget_strings ct_func_string_table = {
 573         .language       = 0x0409,       /* en-US */
 574         .strings        = ct_func_string_defs,
 575 };
 576
 577 static struct usb_gadget_strings *ct_func_strings[] = {
 578         &ct_func_string_table,
 579         NULL,
 580 };
 581
 582 /*-------------------------------------------------------------------------*/
 583 /*                             usb_configuration                           */
 584
 585 int __init hidg_bind_config(struct usb_configuration *c,
 586                             struct hidg_func_descriptor *fdesc, int index)
 587 {
 588         struct f_hidg *hidg;
 589         int status;
 590
 591         if (index >= minors)
 592                 return -ENOENT;
 593
 594         /* maybe allocate device-global string IDs, and patch descriptors */
 595         if (ct_func_string_defs[CT_FUNC_HID_IDX].id == 0) {
 596                 status = usb_string_id(c->cdev);
 597                 if (status < 0)
 598                         return status;
 599                 ct_func_string_defs[CT_FUNC_HID_IDX].id = status;
 600                 hidg_interface_desc.iInterface = status;
 601         }
 602
 603         /* allocate and initialize one new instance */
 604         hidg = kzalloc(sizeof *hidg, GFP_KERNEL);
 605         if (!hidg)
 606                 return -ENOMEM;
 607
 608         hidg->minor = index;
 609         hidg->bInterfaceSubClass = fdesc->subclass;
 610         hidg->bInterfaceProtocol = fdesc->protocol;
 611         hidg->report_length = fdesc->report_length;
 612         hidg->report_desc_length = fdesc->report_desc_length;
 613         hidg->report_desc = kmemdup(fdesc->report_desc,
 614                                     fdesc->report_desc_length,
 615                                     GFP_KERNEL);
 616         if (!hidg->report_desc) {
 617                 kfree(hidg);
 618                 return -ENOMEM;
 619         }
 620
 621         hidg->func.name    = "hid";
 622         hidg->func.strings = ct_func_strings;
 623         hidg->func.bind    = hidg_bind;
 624         hidg->func.unbind  = hidg_unbind;
 625         hidg->func.set_alt = hidg_set_alt;
 626         hidg->func.disable = hidg_disable;
 627         hidg->func.setup   = hidg_setup;
 628
 629         status = usb_add_function(c, &hidg->func);
 630         if (status)
 631                 kfree(hidg);
 632
 633         return status;
 634 }
 635
 636 int __init ghid_setup(struct usb_gadget *g, int count)
 637 {
 638         int status;
 639         dev_t dev;
 640
 641         hidg_class = class_create(THIS_MODULE, "hidg");
 642
 643         status = alloc_chrdev_region(&dev, 0, count, "hidg");
 644         if (!status) {
 645                 major = MAJOR(dev);
 646                 minors = count;
 647         }
 648
 649         return status;
 650 }
 651
 652 void ghid_cleanup(void)
 653 {
 654         if (major) {
 655                 unregister_chrdev_region(MKDEV(major, 0), minors);
 656                 major = minors = 0;
 657         }
 658
 659         class_destroy(hidg_class);
 660         hidg_class = NULL;
 661 }