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/device.h>
  32 #include <linux/notifier.h>
  33 #include <linux/fs.h>
  34 #include <linux/slab.h>
  35 #include <linux/init.h>
  36 #include <linux/list.h>
  37 #include <linux/i2c.h>
  38 #include <linux/i2c-dev.h>
  39 #include <linux/jiffies.h>
  40 #include <linux/uaccess.h>
  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 bus notifications.
  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 = 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 %zu 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,
 160                 size_t count, loff_t *offset)
 161 {
 162         int ret;
 163         char *tmp;
 164         struct i2c_client *client = file->private_data;
 165
 166         if (count > 8192)
 167                 count = 8192;
 168
 169         tmp = memdup_user(buf, count);
 170         if (IS_ERR(tmp))
 171                 return PTR_ERR(tmp);
 172
 173         pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 174                 iminor(file->f_path.dentry->d_inode), count);
 175
 176         ret = i2c_master_send(client, tmp, count);
 177         kfree(tmp);
 178         return ret;
 179 }
 180
 181 static int i2cdev_check(struct device *dev, void *addrp)
 182 {
 183         struct i2c_client *client = i2c_verify_client(dev);
 184
 185         if (!client || client->addr != *(unsigned int *)addrp)
 186                 return 0;
 187
 188         return dev->driver ? -EBUSY : 0;
 189 }
 190
 191 /* walk up mux tree */
 192 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 193 {
 194         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 195         int result;
 196
 197         result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 198         if (!result && parent)
 199                 result = i2cdev_check_mux_parents(parent, addr);
 200
 201         return result;
 202 }
 203
 204 /* recurse down mux tree */
 205 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 206 {
 207         int result;
 208
 209         if (dev->type == &i2c_adapter_type)
 210                 result = device_for_each_child(dev, addrp,
 211                                                 i2cdev_check_mux_children);
 212         else
 213                 result = i2cdev_check(dev, addrp);
 214
 215         return result;
 216 }
 217
 218 /* This address checking function differs from the one in i2c-core
 219    in that it considers an address with a registered device, but no
 220    driver bound to it, as NOT busy. */
 221 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 222 {
 223         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 224         int result = 0;
 225
 226         if (parent)
 227                 result = i2cdev_check_mux_parents(parent, addr);
 228
 229         if (!result)
 230                 result = device_for_each_child(&adapter->dev, &addr,
 231                                                 i2cdev_check_mux_children);
 232
 233         return result;
 234 }
 235
 236 static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
 237                 unsigned long arg)
 238 {
 239         struct i2c_rdwr_ioctl_data rdwr_arg;
 240         struct i2c_msg *rdwr_pa;
 241         u8 __user **data_ptrs;
 242         int i, res;
 243
 244         if (copy_from_user(&rdwr_arg,
 245                            (struct i2c_rdwr_ioctl_data __user *)arg,
 246                            sizeof(rdwr_arg)))
 247                 return -EFAULT;
 248
 249         /* Put an arbitrary limit on the number of messages that can
 250          * be sent at once */
 251         if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
 252                 return -EINVAL;
 253
 254         rdwr_pa = memdup_user(rdwr_arg.msgs,
 255                               rdwr_arg.nmsgs * sizeof(struct i2c_msg));
 256         if (IS_ERR(rdwr_pa))
 257                 return PTR_ERR(rdwr_pa);
 258
 259         data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 260         if (data_ptrs == NULL) {
 261                 kfree(rdwr_pa);
 262                 return -ENOMEM;
 263         }
 264
 265         res = 0;
 266         for (i = 0; i < rdwr_arg.nmsgs; i++) {
 267                 /* Limit the size of the message to a sane amount;
 268                  * and don't let length change either. */
 269                 if ((rdwr_pa[i].len > 8192) ||
 270                     (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 271                         res = -EINVAL;
 272                         break;
 273                 }
 274                 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 275                 rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
 276                 if (IS_ERR(rdwr_pa[i].buf)) {
 277                         res = PTR_ERR(rdwr_pa[i].buf);
 278                         break;
 279                 }
 280         }
 281         if (res < 0) {
 282                 int j;
 283                 for (j = 0; j < i; ++j)
 284                         kfree(rdwr_pa[j].buf);
 285                 kfree(data_ptrs);
 286                 kfree(rdwr_pa);
 287                 return res;
 288         }
 289
 290         res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 291         while (i-- > 0) {
 292                 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 293                         if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 294                                          rdwr_pa[i].len))
 295                                 res = -EFAULT;
 296                 }
 297                 kfree(rdwr_pa[i].buf);
 298         }
 299         kfree(data_ptrs);
 300         kfree(rdwr_pa);
 301         return res;
 302 }
 303
 304 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 305                 unsigned long arg)
 306 {
 307         struct i2c_smbus_ioctl_data data_arg;
 308         union i2c_smbus_data temp;
 309         int datasize, res;
 310
 311         if (copy_from_user(&data_arg,
 312                            (struct i2c_smbus_ioctl_data __user *) arg,
 313                            sizeof(struct i2c_smbus_ioctl_data)))
 314                 return -EFAULT;
 315         if ((data_arg.size != I2C_SMBUS_BYTE) &&
 316             (data_arg.size != I2C_SMBUS_QUICK) &&
 317             (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 318             (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 319             (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 320             (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 321             (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 322             (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 323             (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 324                 dev_dbg(&client->adapter->dev,
 325                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 326                         data_arg.size);
 327                 return -EINVAL;
 328         }
 329         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 330            so the check is valid if size==I2C_SMBUS_QUICK too. */
 331         if ((data_arg.read_write != I2C_SMBUS_READ) &&
 332             (data_arg.read_write != I2C_SMBUS_WRITE)) {
 333                 dev_dbg(&client->adapter->dev,
 334                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 335                         data_arg.read_write);
 336                 return -EINVAL;
 337         }
 338
 339         /* Note that command values are always valid! */
 340
 341         if ((data_arg.size == I2C_SMBUS_QUICK) ||
 342             ((data_arg.size == I2C_SMBUS_BYTE) &&
 343             (data_arg.read_write == I2C_SMBUS_WRITE)))
 344                 /* These are special: we do not use data */
 345                 return i2c_smbus_xfer(client->adapter, client->addr,
 346                                       client->flags, data_arg.read_write,
 347                                       data_arg.command, data_arg.size, NULL);
 348
 349         if (data_arg.data == NULL) {
 350                 dev_dbg(&client->adapter->dev,
 351                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 352                 return -EINVAL;
 353         }
 354
 355         if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 356             (data_arg.size == I2C_SMBUS_BYTE))
 357                 datasize = sizeof(data_arg.data->byte);
 358         else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 359                  (data_arg.size == I2C_SMBUS_PROC_CALL))
 360                 datasize = sizeof(data_arg.data->word);
 361         else /* size == smbus block, i2c block, or block proc. call */
 362                 datasize = sizeof(data_arg.data->block);
 363
 364         if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 365             (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 366             (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 367             (data_arg.read_write == I2C_SMBUS_WRITE)) {
 368                 if (copy_from_user(&temp, data_arg.data, datasize))
 369                         return -EFAULT;
 370         }
 371         if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 372                 /* Convert old I2C block commands to the new
 373                    convention. This preserves binary compatibility. */
 374                 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 375                 if (data_arg.read_write == I2C_SMBUS_READ)
 376                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 377         }
 378         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 379               data_arg.read_write, data_arg.command, data_arg.size, &temp);
 380         if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 381                      (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 382                      (data_arg.read_write == I2C_SMBUS_READ))) {
 383                 if (copy_to_user(data_arg.data, &temp, datasize))
 384                         return -EFAULT;
 385         }
 386         return res;
 387 }
 388
 389 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 390 {
 391         struct i2c_client *client = file->private_data;
 392         unsigned long funcs;
 393
 394         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 395                 cmd, arg);
 396
 397         switch (cmd) {
 398         case I2C_SLAVE:
 399         case I2C_SLAVE_FORCE:
 400                 /* NOTE:  devices set up to work with "new style" drivers
 401                  * can't use I2C_SLAVE, even when the device node is not
 402                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 403                  *
 404                  * Setting the PEC flag here won't affect kernel drivers,
 405                  * which will be using the i2c_client node registered with
 406                  * the driver model core.  Likewise, when that client has
 407                  * the PEC flag already set, the i2c-dev driver won't see
 408                  * (or use) this setting.
 409                  */
 410                 if ((arg > 0x3ff) ||
 411                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 412                         return -EINVAL;
 413                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 414                         return -EBUSY;
 415                 /* REVISIT: address could become busy later */
 416                 client->addr = arg;
 417                 return 0;
 418         case I2C_TENBIT:
 419                 if (arg)
 420                         client->flags |= I2C_M_TEN;
 421                 else
 422                         client->flags &= ~I2C_M_TEN;
 423                 return 0;
 424         case I2C_PEC:
 425                 if (arg)
 426                         client->flags |= I2C_CLIENT_PEC;
 427                 else
 428                         client->flags &= ~I2C_CLIENT_PEC;
 429                 return 0;
 430         case I2C_FUNCS:
 431                 funcs = i2c_get_functionality(client->adapter);
 432                 return put_user(funcs, (unsigned long __user *)arg);
 433
 434         case I2C_RDWR:
 435                 return i2cdev_ioctl_rdrw(client, arg);
 436
 437         case I2C_SMBUS:
 438                 return i2cdev_ioctl_smbus(client, arg);
 439
 440         case I2C_RETRIES:
 441                 client->adapter->retries = arg;
 442                 break;
 443         case I2C_TIMEOUT:
 444                 /* For historical reasons, user-space sets the timeout
 445                  * value in units of 10 ms.
 446                  */
 447                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 448                 break;
 449         default:
 450                 /* NOTE:  returning a fault code here could cause trouble
 451                  * in buggy userspace code.  Some old kernel bugs returned
 452                  * zero in this case, and userspace code might accidentally
 453                  * have depended on that bug.
 454                  */
 455                 return -ENOTTY;
 456         }
 457         return 0;
 458 }
 459
 460 static int i2cdev_open(struct inode *inode, struct file *file)
 461 {
 462         unsigned int minor = iminor(inode);
 463         struct i2c_client *client;
 464         struct i2c_adapter *adap;
 465         struct i2c_dev *i2c_dev;
 466
 467         i2c_dev = i2c_dev_get_by_minor(minor);
 468         if (!i2c_dev)
 469                 return -ENODEV;
 470
 471         adap = i2c_get_adapter(i2c_dev->adap->nr);
 472         if (!adap)
 473                 return -ENODEV;
 474
 475         /* This creates an anonymous i2c_client, which may later be
 476          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 477          *
 478          * This client is ** NEVER REGISTERED ** with the driver model
 479          * or I2C core code!!  It just holds private copies of addressing
 480          * information and maybe a PEC flag.
 481          */
 482         client = kzalloc(sizeof(*client), GFP_KERNEL);
 483         if (!client) {
 484                 i2c_put_adapter(adap);
 485                 return -ENOMEM;
 486         }
 487         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 488
 489         client->adapter = adap;
 490         file->private_data = client;
 491
 492         return 0;
 493 }
 494
 495 static int i2cdev_release(struct inode *inode, struct file *file)
 496 {
 497         struct i2c_client *client = file->private_data;
 498
 499         i2c_put_adapter(client->adapter);
 500         kfree(client);
 501         file->private_data = NULL;
 502
 503         return 0;
 504 }
 505
 506 static const struct file_operations i2cdev_fops = {
 507         .owner          = THIS_MODULE,
 508         .llseek         = no_llseek,
 509         .read           = i2cdev_read,
 510         .write          = i2cdev_write,
 511         .unlocked_ioctl = i2cdev_ioctl,
 512         .open           = i2cdev_open,
 513         .release        = i2cdev_release,
 514 };
 515
 516 /* ------------------------------------------------------------------------- */
 517
 518 static struct class *i2c_dev_class;
 519
 520 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 521 {
 522         struct i2c_adapter *adap;
 523         struct i2c_dev *i2c_dev;
 524         int res;
 525
 526         if (dev->type != &i2c_adapter_type)
 527                 return 0;
 528         adap = to_i2c_adapter(dev);
 529
 530         i2c_dev = get_free_i2c_dev(adap);
 531         if (IS_ERR(i2c_dev))
 532                 return PTR_ERR(i2c_dev);
 533
 534         /* register this i2c device with the driver core */
 535         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 536                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 537                                      "i2c-%d", adap->nr);
 538         if (IS_ERR(i2c_dev->dev)) {
 539                 res = PTR_ERR(i2c_dev->dev);
 540                 goto error;
 541         }
 542         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 543         if (res)
 544                 goto error_destroy;
 545
 546         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 547                  adap->name, adap->nr);
 548         return 0;
 549 error_destroy:
 550         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 551 error:
 552         return_i2c_dev(i2c_dev);
 553         return res;
 554 }
 555
 556 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 557 {
 558         struct i2c_adapter *adap;
 559         struct i2c_dev *i2c_dev;
 560
 561         if (dev->type != &i2c_adapter_type)
 562                 return 0;
 563         adap = to_i2c_adapter(dev);
 564
 565         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 566         if (!i2c_dev) /* attach_adapter must have failed */
 567                 return 0;
 568
 569         device_remove_file(i2c_dev->dev, &dev_attr_name);
 570         return_i2c_dev(i2c_dev);
 571         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 572
 573         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 574         return 0;
 575 }
 576
 577 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 578                          void *data)
 579 {
 580         struct device *dev = data;
 581
 582         switch (action) {
 583         case BUS_NOTIFY_ADD_DEVICE:
 584                 return i2cdev_attach_adapter(dev, NULL);
 585         case BUS_NOTIFY_DEL_DEVICE:
 586                 return i2cdev_detach_adapter(dev, NULL);
 587         }
 588
 589         return 0;
 590 }
 591
 592 static struct notifier_block i2cdev_notifier = {
 593         .notifier_call = i2cdev_notifier_call,
 594 };
 595
 596 /* ------------------------------------------------------------------------- */
 597
 598 /*
 599  * module load/unload record keeping
 600  */
 601
 602 static int __init i2c_dev_init(void)
 603 {
 604         int res;
 605
 606         printk(KERN_INFO "i2c /dev entries driver\n");
 607
 608         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 609         if (res)
 610                 goto out;
 611
 612         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 613         if (IS_ERR(i2c_dev_class)) {
 614                 res = PTR_ERR(i2c_dev_class);
 615                 goto out_unreg_chrdev;
 616         }
 617
 618         /* Keep track of adapters which will be added or removed later */
 619         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 620         if (res)
 621                 goto out_unreg_class;
 622
 623         /* Bind to already existing adapters right away */
 624         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 625
 626         return 0;
 627
 628 out_unreg_class:
 629         class_destroy(i2c_dev_class);
 630 out_unreg_chrdev:
 631         unregister_chrdev(I2C_MAJOR, "i2c");
 632 out:
 633         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 634         return res;
 635 }
 636
 637 static void __exit i2c_dev_exit(void)
 638 {
 639         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 640         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 641         class_destroy(i2c_dev_class);
 642         unregister_chrdev(I2C_MAJOR, "i2c");
 643 }
 644
 645 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 646                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 647 MODULE_DESCRIPTION("I2C /dev entries driver");
 648 MODULE_LICENSE("GPL");
 649
 650 module_init(i2c_dev_init);
 651 module_exit(i2c_dev_exit);