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 <linux/jiffies.h>
  38 #include <linux/uaccess.h>
  39
  40 static 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  */
  51 struct i2c_dev {
  52         struct list_head list;
  53         struct i2c_adapter *adap;
  54         struct device *dev;
  55 };
  56
  57 #define I2C_MINORS      256
  58 static LIST_HEAD(i2c_dev_list);
  59 static DEFINE_SPINLOCK(i2c_dev_list_lock);
  60
  61 static 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;
  71 found:
  72         spin_unlock(&i2c_dev_list_lock);
  73         return i2c_dev;
  74 }
  75
  76 static 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
  97 static 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
 105 static 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 }
 114 static 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
 135 static 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 = 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
 160 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
 161                 size_t count, loff_t *offset)
 162 {
 163         int ret;
 164         char *tmp;
 165         struct i2c_client *client = file->private_data;
 166
 167         if (count > 8192)
 168                 count = 8192;
 169
 170         tmp = memdup_user(buf, count);
 171         if (IS_ERR(tmp))
 172                 return PTR_ERR(tmp);
 173
 174         pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 175                 iminor(file->f_path.dentry->d_inode), count);
 176
 177         ret = i2c_master_send(client, tmp, count);
 178         kfree(tmp);
 179         return ret;
 180 }
 181
 182 static int i2cdev_check(struct device *dev, void *addrp)
 183 {
 184         struct i2c_client *client = i2c_verify_client(dev);
 185
 186         if (!client || client->addr != *(unsigned int *)addrp)
 187                 return 0;
 188
 189         return dev->driver ? -EBUSY : 0;
 190 }
 191
 192 /* walk up mux tree */
 193 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 194 {
 195         int result;
 196
 197         result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 198
 199         if (!result && i2c_parent_is_i2c_adapter(adapter))
 200                 result = i2cdev_check_mux_parents(
 201                                     to_i2c_adapter(adapter->dev.parent), addr);
 202
 203         return result;
 204 }
 205
 206 /* recurse down mux tree */
 207 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 208 {
 209         int result;
 210
 211         if (dev->type == &i2c_adapter_type)
 212                 result = device_for_each_child(dev, addrp,
 213                                                 i2cdev_check_mux_children);
 214         else
 215                 result = i2cdev_check(dev, addrp);
 216
 217         return result;
 218 }
 219
 220 /* This address checking function differs from the one in i2c-core
 221    in that it considers an address with a registered device, but no
 222    driver bound to it, as NOT busy. */
 223 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 224 {
 225         int result = 0;
 226
 227         if (i2c_parent_is_i2c_adapter(adapter))
 228                 result = i2cdev_check_mux_parents(
 229                                     to_i2c_adapter(adapter->dev.parent), addr);
 230
 231         if (!result)
 232                 result = device_for_each_child(&adapter->dev, &addr,
 233                                                 i2cdev_check_mux_children);
 234
 235         return result;
 236 }
 237
 238 static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
 239                 unsigned long arg)
 240 {
 241         struct i2c_rdwr_ioctl_data rdwr_arg;
 242         struct i2c_msg *rdwr_pa;
 243         u8 __user **data_ptrs;
 244         int i, res;
 245
 246         if (copy_from_user(&rdwr_arg,
 247                            (struct i2c_rdwr_ioctl_data __user *)arg,
 248                            sizeof(rdwr_arg)))
 249                 return -EFAULT;
 250
 251         /* Put an arbitrary limit on the number of messages that can
 252          * be sent at once */
 253         if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
 254                 return -EINVAL;
 255
 256         rdwr_pa = kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg), GFP_KERNEL);
 257         if (!rdwr_pa)
 258                 return -ENOMEM;
 259
 260         if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
 261                            rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
 262                 kfree(rdwr_pa);
 263                 return -EFAULT;
 264         }
 265
 266         data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 267         if (data_ptrs == NULL) {
 268                 kfree(rdwr_pa);
 269                 return -ENOMEM;
 270         }
 271
 272         res = 0;
 273         for (i = 0; i < rdwr_arg.nmsgs; i++) {
 274                 /* Limit the size of the message to a sane amount;
 275                  * and don't let length change either. */
 276                 if ((rdwr_pa[i].len > 8192) ||
 277                     (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 278                         res = -EINVAL;
 279                         break;
 280                 }
 281                 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 282                 rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
 283                 if (IS_ERR(rdwr_pa[i].buf)) {
 284                         res = PTR_ERR(rdwr_pa[i].buf);
 285                         break;
 286                 }
 287         }
 288         if (res < 0) {
 289                 int j;
 290                 for (j = 0; j < i; ++j)
 291                         kfree(rdwr_pa[j].buf);
 292                 kfree(data_ptrs);
 293                 kfree(rdwr_pa);
 294                 return res;
 295         }
 296
 297         res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 298         while (i-- > 0) {
 299                 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 300                         if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 301                                          rdwr_pa[i].len))
 302                                 res = -EFAULT;
 303                 }
 304                 kfree(rdwr_pa[i].buf);
 305         }
 306         kfree(data_ptrs);
 307         kfree(rdwr_pa);
 308         return res;
 309 }
 310
 311 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 312                 unsigned long arg)
 313 {
 314         struct i2c_smbus_ioctl_data data_arg;
 315         union i2c_smbus_data temp;
 316         int datasize, res;
 317
 318         if (copy_from_user(&data_arg,
 319                            (struct i2c_smbus_ioctl_data __user *) arg,
 320                            sizeof(struct i2c_smbus_ioctl_data)))
 321                 return -EFAULT;
 322         if ((data_arg.size != I2C_SMBUS_BYTE) &&
 323             (data_arg.size != I2C_SMBUS_QUICK) &&
 324             (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 325             (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 326             (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 327             (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 328             (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 329             (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 330             (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 331                 dev_dbg(&client->adapter->dev,
 332                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 333                         data_arg.size);
 334                 return -EINVAL;
 335         }
 336         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 337            so the check is valid if size==I2C_SMBUS_QUICK too. */
 338         if ((data_arg.read_write != I2C_SMBUS_READ) &&
 339             (data_arg.read_write != I2C_SMBUS_WRITE)) {
 340                 dev_dbg(&client->adapter->dev,
 341                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 342                         data_arg.read_write);
 343                 return -EINVAL;
 344         }
 345
 346         /* Note that command values are always valid! */
 347
 348         if ((data_arg.size == I2C_SMBUS_QUICK) ||
 349             ((data_arg.size == I2C_SMBUS_BYTE) &&
 350             (data_arg.read_write == I2C_SMBUS_WRITE)))
 351                 /* These are special: we do not use data */
 352                 return i2c_smbus_xfer(client->adapter, client->addr,
 353                                       client->flags, data_arg.read_write,
 354                                       data_arg.command, data_arg.size, NULL);
 355
 356         if (data_arg.data == NULL) {
 357                 dev_dbg(&client->adapter->dev,
 358                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 359                 return -EINVAL;
 360         }
 361
 362         if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 363             (data_arg.size == I2C_SMBUS_BYTE))
 364                 datasize = sizeof(data_arg.data->byte);
 365         else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 366                  (data_arg.size == I2C_SMBUS_PROC_CALL))
 367                 datasize = sizeof(data_arg.data->word);
 368         else /* size == smbus block, i2c block, or block proc. call */
 369                 datasize = sizeof(data_arg.data->block);
 370
 371         if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 372             (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 373             (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 374             (data_arg.read_write == I2C_SMBUS_WRITE)) {
 375                 if (copy_from_user(&temp, data_arg.data, datasize))
 376                         return -EFAULT;
 377         }
 378         if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 379                 /* Convert old I2C block commands to the new
 380                    convention. This preserves binary compatibility. */
 381                 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 382                 if (data_arg.read_write == I2C_SMBUS_READ)
 383                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 384         }
 385         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 386               data_arg.read_write, data_arg.command, data_arg.size, &temp);
 387         if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 388                      (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 389                      (data_arg.read_write == I2C_SMBUS_READ))) {
 390                 if (copy_to_user(data_arg.data, &temp, datasize))
 391                         return -EFAULT;
 392         }
 393         return res;
 394 }
 395
 396 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 397 {
 398         struct i2c_client *client = file->private_data;
 399         unsigned long funcs;
 400
 401         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 402                 cmd, arg);
 403
 404         switch (cmd) {
 405         case I2C_SLAVE:
 406         case I2C_SLAVE_FORCE:
 407                 /* NOTE:  devices set up to work with "new style" drivers
 408                  * can't use I2C_SLAVE, even when the device node is not
 409                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 410                  *
 411                  * Setting the PEC flag here won't affect kernel drivers,
 412                  * which will be using the i2c_client node registered with
 413                  * the driver model core.  Likewise, when that client has
 414                  * the PEC flag already set, the i2c-dev driver won't see
 415                  * (or use) this setting.
 416                  */
 417                 if ((arg > 0x3ff) ||
 418                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 419                         return -EINVAL;
 420                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 421                         return -EBUSY;
 422                 /* REVISIT: address could become busy later */
 423                 client->addr = arg;
 424                 return 0;
 425         case I2C_TENBIT:
 426                 if (arg)
 427                         client->flags |= I2C_M_TEN;
 428                 else
 429                         client->flags &= ~I2C_M_TEN;
 430                 return 0;
 431         case I2C_PEC:
 432                 if (arg)
 433                         client->flags |= I2C_CLIENT_PEC;
 434                 else
 435                         client->flags &= ~I2C_CLIENT_PEC;
 436                 return 0;
 437         case I2C_FUNCS:
 438                 funcs = i2c_get_functionality(client->adapter);
 439                 return put_user(funcs, (unsigned long __user *)arg);
 440
 441         case I2C_RDWR:
 442                 return i2cdev_ioctl_rdrw(client, arg);
 443
 444         case I2C_SMBUS:
 445                 return i2cdev_ioctl_smbus(client, arg);
 446
 447         case I2C_RETRIES:
 448                 client->adapter->retries = arg;
 449                 break;
 450         case I2C_TIMEOUT:
 451                 /* For historical reasons, user-space sets the timeout
 452                  * value in units of 10 ms.
 453                  */
 454                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 455                 break;
 456         default:
 457                 /* NOTE:  returning a fault code here could cause trouble
 458                  * in buggy userspace code.  Some old kernel bugs returned
 459                  * zero in this case, and userspace code might accidentally
 460                  * have depended on that bug.
 461                  */
 462                 return -ENOTTY;
 463         }
 464         return 0;
 465 }
 466
 467 static int i2cdev_open(struct inode *inode, struct file *file)
 468 {
 469         unsigned int minor = iminor(inode);
 470         struct i2c_client *client;
 471         struct i2c_adapter *adap;
 472         struct i2c_dev *i2c_dev;
 473
 474         i2c_dev = i2c_dev_get_by_minor(minor);
 475         if (!i2c_dev)
 476                 return -ENODEV;
 477
 478         adap = i2c_get_adapter(i2c_dev->adap->nr);
 479         if (!adap)
 480                 return -ENODEV;
 481
 482         /* This creates an anonymous i2c_client, which may later be
 483          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 484          *
 485          * This client is ** NEVER REGISTERED ** with the driver model
 486          * or I2C core code!!  It just holds private copies of addressing
 487          * information and maybe a PEC flag.
 488          */
 489         client = kzalloc(sizeof(*client), GFP_KERNEL);
 490         if (!client) {
 491                 i2c_put_adapter(adap);
 492                 return -ENOMEM;
 493         }
 494         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 495         client->driver = &i2cdev_driver;
 496
 497         client->adapter = adap;
 498         file->private_data = client;
 499
 500         return 0;
 501 }
 502
 503 static int i2cdev_release(struct inode *inode, struct file *file)
 504 {
 505         struct i2c_client *client = file->private_data;
 506
 507         i2c_put_adapter(client->adapter);
 508         kfree(client);
 509         file->private_data = NULL;
 510
 511         return 0;
 512 }
 513
 514 static const struct file_operations i2cdev_fops = {
 515         .owner          = THIS_MODULE,
 516         .llseek         = no_llseek,
 517         .read           = i2cdev_read,
 518         .write          = i2cdev_write,
 519         .unlocked_ioctl = i2cdev_ioctl,
 520         .open           = i2cdev_open,
 521         .release        = i2cdev_release,
 522 };
 523
 524 /* ------------------------------------------------------------------------- */
 525
 526 /*
 527  * The legacy "i2cdev_driver" is used primarily to get notifications when
 528  * I2C adapters are added or removed, so that each one gets an i2c_dev
 529  * and is thus made available to userspace driver code.
 530  */
 531
 532 static struct class *i2c_dev_class;
 533
 534 static int i2cdev_attach_adapter(struct i2c_adapter *adap)
 535 {
 536         struct i2c_dev *i2c_dev;
 537         int res;
 538
 539         i2c_dev = get_free_i2c_dev(adap);
 540         if (IS_ERR(i2c_dev))
 541                 return PTR_ERR(i2c_dev);
 542
 543         /* register this i2c device with the driver core */
 544         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 545                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 546                                      "i2c-%d", adap->nr);
 547         if (IS_ERR(i2c_dev->dev)) {
 548                 res = PTR_ERR(i2c_dev->dev);
 549                 goto error;
 550         }
 551         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 552         if (res)
 553                 goto error_destroy;
 554
 555         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 556                  adap->name, adap->nr);
 557         return 0;
 558 error_destroy:
 559         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 560 error:
 561         return_i2c_dev(i2c_dev);
 562         return res;
 563 }
 564
 565 static int i2cdev_detach_adapter(struct i2c_adapter *adap)
 566 {
 567         struct i2c_dev *i2c_dev;
 568
 569         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 570         if (!i2c_dev) /* attach_adapter must have failed */
 571                 return 0;
 572
 573         device_remove_file(i2c_dev->dev, &dev_attr_name);
 574         return_i2c_dev(i2c_dev);
 575         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 576
 577         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 578         return 0;
 579 }
 580
 581 static struct i2c_driver i2cdev_driver = {
 582         .driver = {
 583                 .name   = "dev_driver",
 584         },
 585         .attach_adapter = i2cdev_attach_adapter,
 586         .detach_adapter = i2cdev_detach_adapter,
 587 };
 588
 589 /* ------------------------------------------------------------------------- */
 590
 591 /*
 592  * module load/unload record keeping
 593  */
 594
 595 static int __init i2c_dev_init(void)
 596 {
 597         int res;
 598
 599         printk(KERN_INFO "i2c /dev entries driver\n");
 600
 601         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 602         if (res)
 603                 goto out;
 604
 605         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 606         if (IS_ERR(i2c_dev_class)) {
 607                 res = PTR_ERR(i2c_dev_class);
 608                 goto out_unreg_chrdev;
 609         }
 610
 611         res = i2c_add_driver(&i2cdev_driver);
 612         if (res)
 613                 goto out_unreg_class;
 614
 615         return 0;
 616
 617 out_unreg_class:
 618         class_destroy(i2c_dev_class);
 619 out_unreg_chrdev:
 620         unregister_chrdev(I2C_MAJOR, "i2c");
 621 out:
 622         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 623         return res;
 624 }
 625
 626 static void __exit i2c_dev_exit(void)
 627 {
 628         i2c_del_driver(&i2cdev_driver);
 629         class_destroy(i2c_dev_class);
 630         unregister_chrdev(I2C_MAJOR, "i2c");
 631 }
 632
 633 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 634                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 635 MODULE_DESCRIPTION("I2C /dev entries driver");
 636 MODULE_LICENSE("GPL");
 637
 638 module_init(i2c_dev_init);
 639 module_exit(i2c_dev_exit);