linux/drivers/i2c/i2c-dev.c
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   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 <linux/smp_lock.h>
  38#include <asm/uaccess.h>
  39
  40static struct i2c_driver i2cdev_driver;
  41
  42/*
  43 * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  44 * slave (i2c_client) with which messages will be exchanged.  It's coupled
  45 * with a character special file which is accessed by user mode drivers.
  46 *
  47 * The list of i2c_dev structures is parallel to the i2c_adapter lists
  48 * maintained by the driver model, and is updated using notifications
  49 * delivered to the i2cdev_driver.
  50 */
  51struct i2c_dev {
  52        struct list_head list;
  53        struct i2c_adapter *adap;
  54        struct device *dev;
  55};
  56
  57#define I2C_MINORS      256
  58static LIST_HEAD(i2c_dev_list);
  59static DEFINE_SPINLOCK(i2c_dev_list_lock);
  60
  61static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
  62{
  63        struct i2c_dev *i2c_dev;
  64
  65        spin_lock(&i2c_dev_list_lock);
  66        list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
  67                if (i2c_dev->adap->nr == index)
  68                        goto found;
  69        }
  70        i2c_dev = NULL;
  71found:
  72        spin_unlock(&i2c_dev_list_lock);
  73        return i2c_dev;
  74}
  75
  76static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
  77{
  78        struct i2c_dev *i2c_dev;
  79
  80        if (adap->nr >= I2C_MINORS) {
  81                printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
  82                       adap->nr);
  83                return ERR_PTR(-ENODEV);
  84        }
  85
  86        i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
  87        if (!i2c_dev)
  88                return ERR_PTR(-ENOMEM);
  89        i2c_dev->adap = adap;
  90
  91        spin_lock(&i2c_dev_list_lock);
  92        list_add_tail(&i2c_dev->list, &i2c_dev_list);
  93        spin_unlock(&i2c_dev_list_lock);
  94        return i2c_dev;
  95}
  96
  97static void return_i2c_dev(struct i2c_dev *i2c_dev)
  98{
  99        spin_lock(&i2c_dev_list_lock);
 100        list_del(&i2c_dev->list);
 101        spin_unlock(&i2c_dev_list_lock);
 102        kfree(i2c_dev);
 103}
 104
 105static ssize_t show_adapter_name(struct device *dev,
 106                                 struct device_attribute *attr, char *buf)
 107{
 108        struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
 109
 110        if (!i2c_dev)
 111                return -ENODEV;
 112        return sprintf(buf, "%s\n", i2c_dev->adap->name);
 113}
 114static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
 115
 116/* ------------------------------------------------------------------------- */
 117
 118/*
 119 * After opening an instance of this character special file, a file
 120 * descriptor starts out associated only with an i2c_adapter (and bus).
 121 *
 122 * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
 123 * traffic to any devices on the bus used by that adapter.  That's because
 124 * the i2c_msg vectors embed all the addressing information they need, and
 125 * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
 126 * don't support that interface.
 127 *
 128 * To use read()/write() system calls on that file descriptor, or to use
 129 * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
 130 * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
 131 * (never registered) i2c_client so it holds the addressing information
 132 * needed by those system calls and by this SMBus interface.
 133 */
 134
 135static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
 136                            loff_t *offset)
 137{
 138        char *tmp;
 139        int ret;
 140
 141        struct i2c_client *client = (struct i2c_client *)file->private_data;
 142
 143        if (count > 8192)
 144                count = 8192;
 145
 146        tmp = kmalloc(count,GFP_KERNEL);
 147        if (tmp==NULL)
 148                return -ENOMEM;
 149
 150        pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
 151                iminor(file->f_path.dentry->d_inode), count);
 152
 153        ret = i2c_master_recv(client,tmp,count);
 154        if (ret >= 0)
 155                ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
 156        kfree(tmp);
 157        return ret;
 158}
 159
 160static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count,
 161                             loff_t *offset)
 162{
 163        int ret;
 164        char *tmp;
 165        struct i2c_client *client = (struct i2c_client *)file->private_data;
 166
 167        if (count > 8192)
 168                count = 8192;
 169
 170        tmp = kmalloc(count,GFP_KERNEL);
 171        if (tmp==NULL)
 172                return -ENOMEM;
 173        if (copy_from_user(tmp,buf,count)) {
 174                kfree(tmp);
 175                return -EFAULT;
 176        }
 177
 178        pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 179                iminor(file->f_path.dentry->d_inode), count);
 180
 181        ret = i2c_master_send(client,tmp,count);
 182        kfree(tmp);
 183        return ret;
 184}
 185
 186static int i2cdev_check(struct device *dev, void *addrp)
 187{
 188        struct i2c_client *client = i2c_verify_client(dev);
 189
 190        if (!client || client->addr != *(unsigned int *)addrp)
 191                return 0;
 192
 193        return dev->driver ? -EBUSY : 0;
 194}
 195
 196/* This address checking function differs from the one in i2c-core
 197   in that it considers an address with a registered device, but no
 198   driver bound to it, as NOT busy. */
 199static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 200{
 201        return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 202}
 203
 204static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
 205                unsigned long arg)
 206{
 207        struct i2c_rdwr_ioctl_data rdwr_arg;
 208        struct i2c_msg *rdwr_pa;
 209        u8 __user **data_ptrs;
 210        int i, res;
 211
 212        if (copy_from_user(&rdwr_arg,
 213                           (struct i2c_rdwr_ioctl_data __user *)arg,
 214                           sizeof(rdwr_arg)))
 215                return -EFAULT;
 216
 217        /* Put an arbitrary limit on the number of messages that can
 218         * be sent at once */
 219        if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
 220                return -EINVAL;
 221
 222        rdwr_pa = (struct i2c_msg *)
 223                kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
 224                GFP_KERNEL);
 225        if (!rdwr_pa)
 226                return -ENOMEM;
 227
 228        if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
 229                           rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
 230                kfree(rdwr_pa);
 231                return -EFAULT;
 232        }
 233
 234        data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 235        if (data_ptrs == NULL) {
 236                kfree(rdwr_pa);
 237                return -ENOMEM;
 238        }
 239
 240        res = 0;
 241        for (i = 0; i < rdwr_arg.nmsgs; i++) {
 242                /* Limit the size of the message to a sane amount;
 243                 * and don't let length change either. */
 244                if ((rdwr_pa[i].len > 8192) ||
 245                    (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 246                        res = -EINVAL;
 247                        break;
 248                }
 249                data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 250                rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
 251                if (rdwr_pa[i].buf == NULL) {
 252                        res = -ENOMEM;
 253                        break;
 254                }
 255                if (copy_from_user(rdwr_pa[i].buf, data_ptrs[i],
 256                                   rdwr_pa[i].len)) {
 257                                ++i; /* Needs to be kfreed too */
 258                                res = -EFAULT;
 259                        break;
 260                }
 261        }
 262        if (res < 0) {
 263                int j;
 264                for (j = 0; j < i; ++j)
 265                        kfree(rdwr_pa[j].buf);
 266                kfree(data_ptrs);
 267                kfree(rdwr_pa);
 268                return res;
 269        }
 270
 271        res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 272        while (i-- > 0) {
 273                if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 274                        if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 275                                         rdwr_pa[i].len))
 276                                res = -EFAULT;
 277                }
 278                kfree(rdwr_pa[i].buf);
 279        }
 280        kfree(data_ptrs);
 281        kfree(rdwr_pa);
 282        return res;
 283}
 284
 285static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 286                unsigned long arg)
 287{
 288        struct i2c_smbus_ioctl_data data_arg;
 289        union i2c_smbus_data temp;
 290        int datasize, res;
 291
 292        if (copy_from_user(&data_arg,
 293                           (struct i2c_smbus_ioctl_data __user *) arg,
 294                           sizeof(struct i2c_smbus_ioctl_data)))
 295                return -EFAULT;
 296        if ((data_arg.size != I2C_SMBUS_BYTE) &&
 297            (data_arg.size != I2C_SMBUS_QUICK) &&
 298            (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 299            (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 300            (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 301            (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 302            (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 303            (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 304            (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 305                dev_dbg(&client->adapter->dev,
 306                        "size out of range (%x) in ioctl I2C_SMBUS.\n",
 307                        data_arg.size);
 308                return -EINVAL;
 309        }
 310        /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 311           so the check is valid if size==I2C_SMBUS_QUICK too. */
 312        if ((data_arg.read_write != I2C_SMBUS_READ) &&
 313            (data_arg.read_write != I2C_SMBUS_WRITE)) {
 314                dev_dbg(&client->adapter->dev,
 315                        "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 316                        data_arg.read_write);
 317                return -EINVAL;
 318        }
 319
 320        /* Note that command values are always valid! */
 321
 322        if ((data_arg.size == I2C_SMBUS_QUICK) ||
 323            ((data_arg.size == I2C_SMBUS_BYTE) &&
 324            (data_arg.read_write == I2C_SMBUS_WRITE)))
 325                /* These are special: we do not use data */
 326                return i2c_smbus_xfer(client->adapter, client->addr,
 327                                      client->flags, data_arg.read_write,
 328                                      data_arg.command, data_arg.size, NULL);
 329
 330        if (data_arg.data == NULL) {
 331                dev_dbg(&client->adapter->dev,
 332                        "data is NULL pointer in ioctl I2C_SMBUS.\n");
 333                return -EINVAL;
 334        }
 335
 336        if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 337            (data_arg.size == I2C_SMBUS_BYTE))
 338                datasize = sizeof(data_arg.data->byte);
 339        else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 340                 (data_arg.size == I2C_SMBUS_PROC_CALL))
 341                datasize = sizeof(data_arg.data->word);
 342        else /* size == smbus block, i2c block, or block proc. call */
 343                datasize = sizeof(data_arg.data->block);
 344
 345        if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 346            (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 347            (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 348            (data_arg.read_write == I2C_SMBUS_WRITE)) {
 349                if (copy_from_user(&temp, data_arg.data, datasize))
 350                        return -EFAULT;
 351        }
 352        if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 353                /* Convert old I2C block commands to the new
 354                   convention. This preserves binary compatibility. */
 355                data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 356                if (data_arg.read_write == I2C_SMBUS_READ)
 357                        temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 358        }
 359        res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 360              data_arg.read_write, data_arg.command, data_arg.size, &temp);
 361        if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 362                     (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 363                     (data_arg.read_write == I2C_SMBUS_READ))) {
 364                if (copy_to_user(data_arg.data, &temp, datasize))
 365                        return -EFAULT;
 366        }
 367        return res;
 368}
 369
 370static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 371{
 372        struct i2c_client *client = (struct i2c_client *)file->private_data;
 373        unsigned long funcs;
 374
 375        dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 376                cmd, arg);
 377
 378        switch ( cmd ) {
 379        case I2C_SLAVE:
 380        case I2C_SLAVE_FORCE:
 381                /* NOTE:  devices set up to work with "new style" drivers
 382                 * can't use I2C_SLAVE, even when the device node is not
 383                 * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 384                 *
 385                 * Setting the PEC flag here won't affect kernel drivers,
 386                 * which will be using the i2c_client node registered with
 387                 * the driver model core.  Likewise, when that client has
 388                 * the PEC flag already set, the i2c-dev driver won't see
 389                 * (or use) this setting.
 390                 */
 391                if ((arg > 0x3ff) ||
 392                    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 393                        return -EINVAL;
 394                if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 395                        return -EBUSY;
 396                /* REVISIT: address could become busy later */
 397                client->addr = arg;
 398                return 0;
 399        case I2C_TENBIT:
 400                if (arg)
 401                        client->flags |= I2C_M_TEN;
 402                else
 403                        client->flags &= ~I2C_M_TEN;
 404                return 0;
 405        case I2C_PEC:
 406                if (arg)
 407                        client->flags |= I2C_CLIENT_PEC;
 408                else
 409                        client->flags &= ~I2C_CLIENT_PEC;
 410                return 0;
 411        case I2C_FUNCS:
 412                funcs = i2c_get_functionality(client->adapter);
 413                return put_user(funcs, (unsigned long __user *)arg);
 414
 415        case I2C_RDWR:
 416                return i2cdev_ioctl_rdrw(client, arg);
 417
 418        case I2C_SMBUS:
 419                return i2cdev_ioctl_smbus(client, arg);
 420
 421        case I2C_RETRIES:
 422                client->adapter->retries = arg;
 423                break;
 424        case I2C_TIMEOUT:
 425                client->adapter->timeout = arg;
 426                break;
 427        default:
 428                /* NOTE:  returning a fault code here could cause trouble
 429                 * in buggy userspace code.  Some old kernel bugs returned
 430                 * zero in this case, and userspace code might accidentally
 431                 * have depended on that bug.
 432                 */
 433                return -ENOTTY;
 434        }
 435        return 0;
 436}
 437
 438static int i2cdev_open(struct inode *inode, struct file *file)
 439{
 440        unsigned int minor = iminor(inode);
 441        struct i2c_client *client;
 442        struct i2c_adapter *adap;
 443        struct i2c_dev *i2c_dev;
 444        int ret = 0;
 445
 446        lock_kernel();
 447        i2c_dev = i2c_dev_get_by_minor(minor);
 448        if (!i2c_dev) {
 449                ret = -ENODEV;
 450                goto out;
 451        }
 452
 453        adap = i2c_get_adapter(i2c_dev->adap->nr);
 454        if (!adap) {
 455                ret = -ENODEV;
 456                goto out;
 457        }
 458
 459        /* This creates an anonymous i2c_client, which may later be
 460         * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 461         *
 462         * This client is ** NEVER REGISTERED ** with the driver model
 463         * or I2C core code!!  It just holds private copies of addressing
 464         * information and maybe a PEC flag.
 465         */
 466        client = kzalloc(sizeof(*client), GFP_KERNEL);
 467        if (!client) {
 468                i2c_put_adapter(adap);
 469                ret = -ENOMEM;
 470                goto out;
 471        }
 472        snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 473        client->driver = &i2cdev_driver;
 474
 475        client->adapter = adap;
 476        file->private_data = client;
 477
 478out:
 479        unlock_kernel();
 480        return ret;
 481}
 482
 483static int i2cdev_release(struct inode *inode, struct file *file)
 484{
 485        struct i2c_client *client = file->private_data;
 486
 487        i2c_put_adapter(client->adapter);
 488        kfree(client);
 489        file->private_data = NULL;
 490
 491        return 0;
 492}
 493
 494static const struct file_operations i2cdev_fops = {
 495        .owner          = THIS_MODULE,
 496        .llseek         = no_llseek,
 497        .read           = i2cdev_read,
 498        .write          = i2cdev_write,
 499        .unlocked_ioctl = i2cdev_ioctl,
 500        .open           = i2cdev_open,
 501        .release        = i2cdev_release,
 502};
 503
 504/* ------------------------------------------------------------------------- */
 505
 506/*
 507 * The legacy "i2cdev_driver" is used primarily to get notifications when
 508 * I2C adapters are added or removed, so that each one gets an i2c_dev
 509 * and is thus made available to userspace driver code.
 510 */
 511
 512static struct class *i2c_dev_class;
 513
 514static int i2cdev_attach_adapter(struct i2c_adapter *adap)
 515{
 516        struct i2c_dev *i2c_dev;
 517        int res;
 518
 519        i2c_dev = get_free_i2c_dev(adap);
 520        if (IS_ERR(i2c_dev))
 521                return PTR_ERR(i2c_dev);
 522
 523        /* register this i2c device with the driver core */
 524        i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 525                                     MKDEV(I2C_MAJOR, adap->nr), NULL,
 526                                     "i2c-%d", adap->nr);
 527        if (IS_ERR(i2c_dev->dev)) {
 528                res = PTR_ERR(i2c_dev->dev);
 529                goto error;
 530        }
 531        res = device_create_file(i2c_dev->dev, &dev_attr_name);
 532        if (res)
 533                goto error_destroy;
 534
 535        pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 536                 adap->name, adap->nr);
 537        return 0;
 538error_destroy:
 539        device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 540error:
 541        return_i2c_dev(i2c_dev);
 542        return res;
 543}
 544
 545static int i2cdev_detach_adapter(struct i2c_adapter *adap)
 546{
 547        struct i2c_dev *i2c_dev;
 548
 549        i2c_dev = i2c_dev_get_by_minor(adap->nr);
 550        if (!i2c_dev) /* attach_adapter must have failed */
 551                return 0;
 552
 553        device_remove_file(i2c_dev->dev, &dev_attr_name);
 554        return_i2c_dev(i2c_dev);
 555        device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 556
 557        pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 558        return 0;
 559}
 560
 561static struct i2c_driver i2cdev_driver = {
 562        .driver = {
 563                .name   = "dev_driver",
 564        },
 565        .attach_adapter = i2cdev_attach_adapter,
 566        .detach_adapter = i2cdev_detach_adapter,
 567};
 568
 569/* ------------------------------------------------------------------------- */
 570
 571/*
 572 * module load/unload record keeping
 573 */
 574
 575static int __init i2c_dev_init(void)
 576{
 577        int res;
 578
 579        printk(KERN_INFO "i2c /dev entries driver\n");
 580
 581        res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 582        if (res)
 583                goto out;
 584
 585        i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 586        if (IS_ERR(i2c_dev_class)) {
 587                res = PTR_ERR(i2c_dev_class);
 588                goto out_unreg_chrdev;
 589        }
 590
 591        res = i2c_add_driver(&i2cdev_driver);
 592        if (res)
 593                goto out_unreg_class;
 594
 595        return 0;
 596
 597out_unreg_class:
 598        class_destroy(i2c_dev_class);
 599out_unreg_chrdev:
 600        unregister_chrdev(I2C_MAJOR, "i2c");
 601out:
 602        printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 603        return res;
 604}
 605
 606static void __exit i2c_dev_exit(void)
 607{
 608        i2c_del_driver(&i2cdev_driver);
 609        class_destroy(i2c_dev_class);
 610        unregister_chrdev(I2C_MAJOR,"i2c");
 611}
 612
 613MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 614                "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 615MODULE_DESCRIPTION("I2C /dev entries driver");
 616MODULE_LICENSE("GPL");
 617
 618module_init(i2c_dev_init);
 619module_exit(i2c_dev_exit);
 620