drivers/i2c/i2c-dev.c

   1 /*
   2     i2c-dev.c - i2c-bus driver, char device interface
   3
   4     Copyright (C) 1995-97 Simon G. Vogl
   5     Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
   6     Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
  24    But I have used so much of his original code and ideas that it seems
  25    only fair to recognize him as co-author -- Frodo */
  26
  27 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/fs.h>
  32 #include <linux/slab.h>
  33 #include <linux/init.h>
  34 #include <linux/list.h>
  35 #include <linux/i2c.h>
  36 #include <linux/i2c-dev.h>
  37 #include <asm/uaccess.h>
  38
  39 static struct i2c_driver i2cdev_driver;
  40
  41 /*
  42  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  43  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  44  * with a character special file which is accessed by user mode drivers.
  45  *
  46  * The list of i2c_dev structures is parallel to the i2c_adapter lists
  47  * maintained by the driver model, and is updated using notifications
  48  * delivered to the i2cdev_driver.
  49  */
  50 struct i2c_dev {
  51         struct list_head list;
  52         struct i2c_adapter *adap;
  53         struct device *dev;
  54 };
  55
  56 #define I2C_MINORS      256
  57 static LIST_HEAD(i2c_dev_list);
  58 static DEFINE_SPINLOCK(i2c_dev_list_lock);
  59
  60 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
  61 {
  62         struct i2c_dev *i2c_dev;
  63
  64         spin_lock(&i2c_dev_list_lock);
  65         list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
  66                 if (i2c_dev->adap->nr == index)
  67                         goto found;
  68         }
  69         i2c_dev = NULL;
  70 found:
  71         spin_unlock(&i2c_dev_list_lock);
  72         return i2c_dev;
  73 }
  74
  75 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
  76 {
  77         struct i2c_dev *i2c_dev;
  78
  79         if (adap->nr >= I2C_MINORS) {
  80                 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
  81                        adap->nr);
  82                 return ERR_PTR(-ENODEV);
  83         }
  84
  85         i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
  86         if (!i2c_dev)
  87                 return ERR_PTR(-ENOMEM);
  88         i2c_dev->adap = adap;
  89
  90         spin_lock(&i2c_dev_list_lock);
  91         list_add_tail(&i2c_dev->list, &i2c_dev_list);
  92         spin_unlock(&i2c_dev_list_lock);
  93         return i2c_dev;
  94 }
  95
  96 static void return_i2c_dev(struct i2c_dev *i2c_dev)
  97 {
  98         spin_lock(&i2c_dev_list_lock);
  99         list_del(&i2c_dev->list);
 100         spin_unlock(&i2c_dev_list_lock);
 101         kfree(i2c_dev);
 102 }
 103
 104 static ssize_t show_adapter_name(struct device *dev,
 105                                  struct device_attribute *attr, char *buf)
 106 {
 107         struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
 108
 109         if (!i2c_dev)
 110                 return -ENODEV;
 111         return sprintf(buf, "%s\n", i2c_dev->adap->name);
 112 }
 113 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
 114
 115 /* ------------------------------------------------------------------------- */
 116
 117 /*
 118  * After opening an instance of this character special file, a file
 119  * descriptor starts out associated only with an i2c_adapter (and bus).
 120  *
 121  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
 122  * traffic to any devices on the bus used by that adapter.  That's because
 123  * the i2c_msg vectors embed all the addressing information they need, and
 124  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
 125  * don't support that interface.
 126  *
 127  * To use read()/write() system calls on that file descriptor, or to use
 128  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
 129  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
 130  * (never registered) i2c_client so it holds the addressing information
 131  * needed by those system calls and by this SMBus interface.
 132  */
 133
 134 static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
 135                             loff_t *offset)
 136 {
 137         char *tmp;
 138         int ret;
 139
 140         struct i2c_client *client = (struct i2c_client *)file->private_data;
 141
 142         if (count > 8192)
 143                 count = 8192;
 144
 145         tmp = kmalloc(count,GFP_KERNEL);
 146         if (tmp==NULL)
 147                 return -ENOMEM;
 148
 149         pr_debug("i2c-dev: i2c-%d reading %zd bytes.\n",
 150                 iminor(file->f_path.dentry->d_inode), count);
 151
 152         ret = i2c_master_recv(client,tmp,count);
 153         if (ret >= 0)
 154                 ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
 155         kfree(tmp);
 156         return ret;
 157 }
 158
 159 static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count,
 160                              loff_t *offset)
 161 {
 162         int ret;
 163         char *tmp;
 164         struct i2c_client *client = (struct i2c_client *)file->private_data;
 165
 166         if (count > 8192)
 167                 count = 8192;
 168
 169         tmp = kmalloc(count,GFP_KERNEL);
 170         if (tmp==NULL)
 171                 return -ENOMEM;
 172         if (copy_from_user(tmp,buf,count)) {
 173                 kfree(tmp);
 174                 return -EFAULT;
 175         }
 176
 177         pr_debug("i2c-dev: i2c-%d writing %zd bytes.\n",
 178                 iminor(file->f_path.dentry->d_inode), count);
 179
 180         ret = i2c_master_send(client,tmp,count);
 181         kfree(tmp);
 182         return ret;
 183 }
 184
 185 /* This address checking function differs from the one in i2c-core
 186    in that it considers an address with a registered device, but no
 187    bound driver, as NOT busy. */
 188 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 189 {
 190         struct list_head *item;
 191         struct i2c_client *client;
 192         int res = 0;
 193
 194         mutex_lock(&adapter->clist_lock);
 195         list_for_each(item, &adapter->clients) {
 196                 client = list_entry(item, struct i2c_client, list);
 197                 if (client->addr == addr) {
 198                         if (client->driver)
 199                                 res = -EBUSY;
 200                         break;
 201                 }
 202         }
 203         mutex_unlock(&adapter->clist_lock);
 204
 205         return res;
 206 }
 207
 208 static int i2cdev_ioctl(struct inode *inode, struct file *file,
 209                 unsigned int cmd, unsigned long arg)
 210 {
 211         struct i2c_client *client = (struct i2c_client *)file->private_data;
 212         struct i2c_rdwr_ioctl_data rdwr_arg;
 213         struct i2c_smbus_ioctl_data data_arg;
 214         union i2c_smbus_data temp;
 215         struct i2c_msg *rdwr_pa;
 216         u8 __user **data_ptrs;
 217         int i,datasize,res;
 218         unsigned long funcs;
 219
 220         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 221                 cmd, arg);
 222
 223         switch ( cmd ) {
 224         case I2C_SLAVE:
 225         case I2C_SLAVE_FORCE:
 226                 /* NOTE:  devices set up to work with "new style" drivers
 227                  * can't use I2C_SLAVE, even when the device node is not
 228                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 229                  *
 230                  * Setting the PEC flag here won't affect kernel drivers,
 231                  * which will be using the i2c_client node registered with
 232                  * the driver model core.  Likewise, when that client has
 233                  * the PEC flag already set, the i2c-dev driver won't see
 234                  * (or use) this setting.
 235                  */
 236                 if ((arg > 0x3ff) ||
 237                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 238                         return -EINVAL;
 239                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 240                         return -EBUSY;
 241                 /* REVISIT: address could become busy later */
 242                 client->addr = arg;
 243                 return 0;
 244         case I2C_TENBIT:
 245                 if (arg)
 246                         client->flags |= I2C_M_TEN;
 247                 else
 248                         client->flags &= ~I2C_M_TEN;
 249                 return 0;
 250         case I2C_PEC:
 251                 if (arg)
 252                         client->flags |= I2C_CLIENT_PEC;
 253                 else
 254                         client->flags &= ~I2C_CLIENT_PEC;
 255                 return 0;
 256         case I2C_FUNCS:
 257                 funcs = i2c_get_functionality(client->adapter);
 258                 return put_user(funcs, (unsigned long __user *)arg);
 259
 260         case I2C_RDWR:
 261                 if (copy_from_user(&rdwr_arg,
 262                                    (struct i2c_rdwr_ioctl_data __user *)arg,
 263                                    sizeof(rdwr_arg)))
 264                         return -EFAULT;
 265
 266                 /* Put an arbitrary limit on the number of messages that can
 267                  * be sent at once */
 268                 if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
 269                         return -EINVAL;
 270
 271                 rdwr_pa = (struct i2c_msg *)
 272                         kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
 273                         GFP_KERNEL);
 274
 275                 if (rdwr_pa == NULL) return -ENOMEM;
 276
 277                 if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
 278                                    rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
 279                         kfree(rdwr_pa);
 280                         return -EFAULT;
 281                 }
 282
 283                 data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 284                 if (data_ptrs == NULL) {
 285                         kfree(rdwr_pa);
 286                         return -ENOMEM;
 287                 }
 288
 289                 res = 0;
 290                 for( i=0; i<rdwr_arg.nmsgs; i++ ) {
 291                         /* Limit the size of the message to a sane amount;
 292                          * and don't let length change either. */
 293                         if ((rdwr_pa[i].len > 8192) ||
 294                             (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 295                                 res = -EINVAL;
 296                                 break;
 297                         }
 298                         data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 299                         rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
 300                         if(rdwr_pa[i].buf == NULL) {
 301                                 res = -ENOMEM;
 302                                 break;
 303                         }
 304                         if(copy_from_user(rdwr_pa[i].buf,
 305                                 data_ptrs[i],
 306                                 rdwr_pa[i].len)) {
 307                                         ++i; /* Needs to be kfreed too */
 308                                         res = -EFAULT;
 309                                 break;
 310                         }
 311                 }
 312                 if (res < 0) {
 313                         int j;
 314                         for (j = 0; j < i; ++j)
 315                                 kfree(rdwr_pa[j].buf);
 316                         kfree(data_ptrs);
 317                         kfree(rdwr_pa);
 318                         return res;
 319                 }
 320
 321                 res = i2c_transfer(client->adapter,
 322                         rdwr_pa,
 323                         rdwr_arg.nmsgs);
 324                 while(i-- > 0) {
 325                         if( res>=0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 326                                 if(copy_to_user(
 327                                         data_ptrs[i],
 328                                         rdwr_pa[i].buf,
 329                                         rdwr_pa[i].len)) {
 330                                         res = -EFAULT;
 331                                 }
 332                         }
 333                         kfree(rdwr_pa[i].buf);
 334                 }
 335                 kfree(data_ptrs);
 336                 kfree(rdwr_pa);
 337                 return res;
 338
 339         case I2C_SMBUS:
 340                 if (copy_from_user(&data_arg,
 341                                    (struct i2c_smbus_ioctl_data __user *) arg,
 342                                    sizeof(struct i2c_smbus_ioctl_data)))
 343                         return -EFAULT;
 344                 if ((data_arg.size != I2C_SMBUS_BYTE) &&
 345                     (data_arg.size != I2C_SMBUS_QUICK) &&
 346                     (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 347                     (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 348                     (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 349                     (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 350                     (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 351                     (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 352                     (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 353                         dev_dbg(&client->adapter->dev,
 354                                 "size out of range (%x) in ioctl I2C_SMBUS.\n",
 355                                 data_arg.size);
 356                         return -EINVAL;
 357                 }
 358                 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 359                    so the check is valid if size==I2C_SMBUS_QUICK too. */
 360                 if ((data_arg.read_write != I2C_SMBUS_READ) &&
 361                     (data_arg.read_write != I2C_SMBUS_WRITE)) {
 362                         dev_dbg(&client->adapter->dev,
 363                                 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 364                                 data_arg.read_write);
 365                         return -EINVAL;
 366                 }
 367
 368                 /* Note that command values are always valid! */
 369
 370                 if ((data_arg.size == I2C_SMBUS_QUICK) ||
 371                     ((data_arg.size == I2C_SMBUS_BYTE) &&
 372                     (data_arg.read_write == I2C_SMBUS_WRITE)))
 373                         /* These are special: we do not use data */
 374                         return i2c_smbus_xfer(client->adapter, client->addr,
 375                                               client->flags,
 376                                               data_arg.read_write,
 377                                               data_arg.command,
 378                                               data_arg.size, NULL);
 379
 380                 if (data_arg.data == NULL) {
 381                         dev_dbg(&client->adapter->dev,
 382                                 "data is NULL pointer in ioctl I2C_SMBUS.\n");
 383                         return -EINVAL;
 384                 }
 385
 386                 if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 387                     (data_arg.size == I2C_SMBUS_BYTE))
 388                         datasize = sizeof(data_arg.data->byte);
 389                 else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 390                          (data_arg.size == I2C_SMBUS_PROC_CALL))
 391                         datasize = sizeof(data_arg.data->word);
 392                 else /* size == smbus block, i2c block, or block proc. call */
 393                         datasize = sizeof(data_arg.data->block);
 394
 395                 if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 396                     (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 397                     (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 398                     (data_arg.read_write == I2C_SMBUS_WRITE)) {
 399                         if (copy_from_user(&temp, data_arg.data, datasize))
 400                                 return -EFAULT;
 401                 }
 402                 if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 403                         /* Convert old I2C block commands to the new
 404                            convention. This preserves binary compatibility. */
 405                         data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 406                         if (data_arg.read_write == I2C_SMBUS_READ)
 407                                 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 408                 }
 409                 res = i2c_smbus_xfer(client->adapter,client->addr,client->flags,
 410                       data_arg.read_write,
 411                       data_arg.command,data_arg.size,&temp);
 412                 if (! res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 413                               (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 414                               (data_arg.read_write == I2C_SMBUS_READ))) {
 415                         if (copy_to_user(data_arg.data, &temp, datasize))
 416                                 return -EFAULT;
 417                 }
 418                 return res;
 419         case I2C_RETRIES:
 420                 client->adapter->retries = arg;
 421                 break;
 422         case I2C_TIMEOUT:
 423                 client->adapter->timeout = arg;
 424                 break;
 425         default:
 426                 /* NOTE:  returning a fault code here could cause trouble
 427                  * in buggy userspace code.  Some old kernel bugs returned
 428                  * zero in this case, and userspace code might accidentally
 429                  * have depended on that bug.
 430                  */
 431                 return -ENOTTY;
 432         }
 433         return 0;
 434 }
 435
 436 static int i2cdev_open(struct inode *inode, struct file *file)
 437 {
 438         unsigned int minor = iminor(inode);
 439         struct i2c_client *client;
 440         struct i2c_adapter *adap;
 441         struct i2c_dev *i2c_dev;
 442
 443         i2c_dev = i2c_dev_get_by_minor(minor);
 444         if (!i2c_dev)
 445                 return -ENODEV;
 446
 447         adap = i2c_get_adapter(i2c_dev->adap->nr);
 448         if (!adap)
 449                 return -ENODEV;
 450
 451         /* This creates an anonymous i2c_client, which may later be
 452          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 453          *
 454          * This client is ** NEVER REGISTERED ** with the driver model
 455          * or I2C core code!!  It just holds private copies of addressing
 456          * information and maybe a PEC flag.
 457          */
 458         client = kzalloc(sizeof(*client), GFP_KERNEL);
 459         if (!client) {
 460                 i2c_put_adapter(adap);
 461                 return -ENOMEM;
 462         }
 463         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 464         client->driver = &i2cdev_driver;
 465
 466         client->adapter = adap;
 467         file->private_data = client;
 468
 469         return 0;
 470 }
 471
 472 static int i2cdev_release(struct inode *inode, struct file *file)
 473 {
 474         struct i2c_client *client = file->private_data;
 475
 476         i2c_put_adapter(client->adapter);
 477         kfree(client);
 478         file->private_data = NULL;
 479
 480         return 0;
 481 }
 482
 483 static const struct file_operations i2cdev_fops = {
 484         .owner          = THIS_MODULE,
 485         .llseek         = no_llseek,
 486         .read           = i2cdev_read,
 487         .write          = i2cdev_write,
 488         .ioctl          = i2cdev_ioctl,
 489         .open           = i2cdev_open,
 490         .release        = i2cdev_release,
 491 };
 492
 493 /* ------------------------------------------------------------------------- */
 494
 495 /*
 496  * The legacy "i2cdev_driver" is used primarily to get notifications when
 497  * I2C adapters are added or removed, so that each one gets an i2c_dev
 498  * and is thus made available to userspace driver code.
 499  */
 500
 501 static struct class *i2c_dev_class;
 502
 503 static int i2cdev_attach_adapter(struct i2c_adapter *adap)
 504 {
 505         struct i2c_dev *i2c_dev;
 506         int res;
 507
 508         i2c_dev = get_free_i2c_dev(adap);
 509         if (IS_ERR(i2c_dev))
 510                 return PTR_ERR(i2c_dev);
 511
 512         /* register this i2c device with the driver core */
 513         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 514                                      MKDEV(I2C_MAJOR, adap->nr),
 515                                      "i2c-%d", adap->nr);
 516         if (IS_ERR(i2c_dev->dev)) {
 517                 res = PTR_ERR(i2c_dev->dev);
 518                 goto error;
 519         }
 520         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 521         if (res)
 522                 goto error_destroy;
 523
 524         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 525                  adap->name, adap->nr);
 526         return 0;
 527 error_destroy:
 528         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 529 error:
 530         return_i2c_dev(i2c_dev);
 531         return res;
 532 }
 533
 534 static int i2cdev_detach_adapter(struct i2c_adapter *adap)
 535 {
 536         struct i2c_dev *i2c_dev;
 537
 538         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 539         if (!i2c_dev) /* attach_adapter must have failed */
 540                 return 0;
 541
 542         device_remove_file(i2c_dev->dev, &dev_attr_name);
 543         return_i2c_dev(i2c_dev);
 544         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 545
 546         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 547         return 0;
 548 }
 549
 550 static int i2cdev_detach_client(struct i2c_client *client)
 551 {
 552         return 0;
 553 }
 554
 555 static struct i2c_driver i2cdev_driver = {
 556         .driver = {
 557                 .name   = "dev_driver",
 558         },
 559         .id             = I2C_DRIVERID_I2CDEV,
 560         .attach_adapter = i2cdev_attach_adapter,
 561         .detach_adapter = i2cdev_detach_adapter,
 562         .detach_client  = i2cdev_detach_client,
 563 };
 564
 565 /* ------------------------------------------------------------------------- */
 566
 567 /*
 568  * module load/unload record keeping
 569  */
 570
 571 static int __init i2c_dev_init(void)
 572 {
 573         int res;
 574
 575         printk(KERN_INFO "i2c /dev entries driver\n");
 576
 577         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 578         if (res)
 579                 goto out;
 580
 581         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 582         if (IS_ERR(i2c_dev_class))
 583                 goto out_unreg_chrdev;
 584
 585         res = i2c_add_driver(&i2cdev_driver);
 586         if (res)
 587                 goto out_unreg_class;
 588
 589         return 0;
 590
 591 out_unreg_class:
 592         class_destroy(i2c_dev_class);
 593 out_unreg_chrdev:
 594         unregister_chrdev(I2C_MAJOR, "i2c");
 595 out:
 596         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 597         return res;
 598 }
 599
 600 static void __exit i2c_dev_exit(void)
 601 {
 602         i2c_del_driver(&i2cdev_driver);
 603         class_destroy(i2c_dev_class);
 604         unregister_chrdev(I2C_MAJOR,"i2c");
 605 }
 606
 607 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 608                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 609 MODULE_DESCRIPTION("I2C /dev entries driver");
 610 MODULE_LICENSE("GPL");
 611
 612 module_init(i2c_dev_init);
 613 module_exit(i2c_dev_exit);