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., 51 Franklin Street, Fifth Floor, Boston,
  21     MA 02110-1301 USA.
  22 */
  23
  24 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
  25    But I have used so much of his original code and ideas that it seems
  26    only fair to recognize him as co-author -- Frodo */
  27
  28 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
  29
  30 #include <linux/kernel.h>
  31 #include <linux/module.h>
  32 #include <linux/device.h>
  33 #include <linux/notifier.h>
  34 #include <linux/fs.h>
  35 #include <linux/slab.h>
  36 #include <linux/init.h>
  37 #include <linux/list.h>
  38 #include <linux/i2c.h>
  39 #include <linux/i2c-dev.h>
  40 #include <linux/jiffies.h>
  41 #include <linux/uaccess.h>
  42
  43 /*
  44  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  45  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  46  * with a character special file which is accessed by user mode drivers.
  47  *
  48  * The list of i2c_dev structures is parallel to the i2c_adapter lists
  49  * maintained by the driver model, and is updated using bus notifications.
  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         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 196         int result;
 197
 198         result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 199         if (!result && parent)
 200                 result = i2cdev_check_mux_parents(parent, addr);
 201
 202         return result;
 203 }
 204
 205 /* recurse down mux tree */
 206 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 207 {
 208         int result;
 209
 210         if (dev->type == &i2c_adapter_type)
 211                 result = device_for_each_child(dev, addrp,
 212                                                 i2cdev_check_mux_children);
 213         else
 214                 result = i2cdev_check(dev, addrp);
 215
 216         return result;
 217 }
 218
 219 /* This address checking function differs from the one in i2c-core
 220    in that it considers an address with a registered device, but no
 221    driver bound to it, as NOT busy. */
 222 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 223 {
 224         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 225         int result = 0;
 226
 227         if (parent)
 228                 result = i2cdev_check_mux_parents(parent, addr);
 229
 230         if (!result)
 231                 result = device_for_each_child(&adapter->dev, &addr,
 232                                                 i2cdev_check_mux_children);
 233
 234         return result;
 235 }
 236
 237 static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
 238                 unsigned long arg)
 239 {
 240         struct i2c_rdwr_ioctl_data rdwr_arg;
 241         struct i2c_msg *rdwr_pa;
 242         u8 __user **data_ptrs;
 243         int i, res;
 244
 245         if (copy_from_user(&rdwr_arg,
 246                            (struct i2c_rdwr_ioctl_data __user *)arg,
 247                            sizeof(rdwr_arg)))
 248                 return -EFAULT;
 249
 250         /* Put an arbitrary limit on the number of messages that can
 251          * be sent at once */
 252         if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
 253                 return -EINVAL;
 254
 255         rdwr_pa = memdup_user(rdwr_arg.msgs,
 256                               rdwr_arg.nmsgs * sizeof(struct i2c_msg));
 257         if (IS_ERR(rdwr_pa))
 258                 return PTR_ERR(rdwr_pa);
 259
 260         data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 261         if (data_ptrs == NULL) {
 262                 kfree(rdwr_pa);
 263                 return -ENOMEM;
 264         }
 265
 266         res = 0;
 267         for (i = 0; i < rdwr_arg.nmsgs; i++) {
 268                 /* Limit the size of the message to a sane amount;
 269                  * and don't let length change either. */
 270                 if ((rdwr_pa[i].len > 8192) ||
 271                     (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 272                         res = -EINVAL;
 273                         break;
 274                 }
 275                 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 276                 rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
 277                 if (IS_ERR(rdwr_pa[i].buf)) {
 278                         res = PTR_ERR(rdwr_pa[i].buf);
 279                         break;
 280                 }
 281         }
 282         if (res < 0) {
 283                 int j;
 284                 for (j = 0; j < i; ++j)
 285                         kfree(rdwr_pa[j].buf);
 286                 kfree(data_ptrs);
 287                 kfree(rdwr_pa);
 288                 return res;
 289         }
 290
 291         res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 292         while (i-- > 0) {
 293                 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 294                         if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 295                                          rdwr_pa[i].len))
 296                                 res = -EFAULT;
 297                 }
 298                 kfree(rdwr_pa[i].buf);
 299         }
 300         kfree(data_ptrs);
 301         kfree(rdwr_pa);
 302         return res;
 303 }
 304
 305 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 306                 unsigned long arg)
 307 {
 308         struct i2c_smbus_ioctl_data data_arg;
 309         union i2c_smbus_data temp;
 310         int datasize, res;
 311
 312         if (copy_from_user(&data_arg,
 313                            (struct i2c_smbus_ioctl_data __user *) arg,
 314                            sizeof(struct i2c_smbus_ioctl_data)))
 315                 return -EFAULT;
 316         if ((data_arg.size != I2C_SMBUS_BYTE) &&
 317             (data_arg.size != I2C_SMBUS_QUICK) &&
 318             (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 319             (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 320             (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 321             (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 322             (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 323             (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 324             (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 325                 dev_dbg(&client->adapter->dev,
 326                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 327                         data_arg.size);
 328                 return -EINVAL;
 329         }
 330         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 331            so the check is valid if size==I2C_SMBUS_QUICK too. */
 332         if ((data_arg.read_write != I2C_SMBUS_READ) &&
 333             (data_arg.read_write != I2C_SMBUS_WRITE)) {
 334                 dev_dbg(&client->adapter->dev,
 335                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 336                         data_arg.read_write);
 337                 return -EINVAL;
 338         }
 339
 340         /* Note that command values are always valid! */
 341
 342         if ((data_arg.size == I2C_SMBUS_QUICK) ||
 343             ((data_arg.size == I2C_SMBUS_BYTE) &&
 344             (data_arg.read_write == I2C_SMBUS_WRITE)))
 345                 /* These are special: we do not use data */
 346                 return i2c_smbus_xfer(client->adapter, client->addr,
 347                                       client->flags, data_arg.read_write,
 348                                       data_arg.command, data_arg.size, NULL);
 349
 350         if (data_arg.data == NULL) {
 351                 dev_dbg(&client->adapter->dev,
 352                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 353                 return -EINVAL;
 354         }
 355
 356         if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 357             (data_arg.size == I2C_SMBUS_BYTE))
 358                 datasize = sizeof(data_arg.data->byte);
 359         else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 360                  (data_arg.size == I2C_SMBUS_PROC_CALL))
 361                 datasize = sizeof(data_arg.data->word);
 362         else /* size == smbus block, i2c block, or block proc. call */
 363                 datasize = sizeof(data_arg.data->block);
 364
 365         if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 366             (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 367             (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 368             (data_arg.read_write == I2C_SMBUS_WRITE)) {
 369                 if (copy_from_user(&temp, data_arg.data, datasize))
 370                         return -EFAULT;
 371         }
 372         if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 373                 /* Convert old I2C block commands to the new
 374                    convention. This preserves binary compatibility. */
 375                 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 376                 if (data_arg.read_write == I2C_SMBUS_READ)
 377                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 378         }
 379         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 380               data_arg.read_write, data_arg.command, data_arg.size, &temp);
 381         if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 382                      (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 383                      (data_arg.read_write == I2C_SMBUS_READ))) {
 384                 if (copy_to_user(data_arg.data, &temp, datasize))
 385                         return -EFAULT;
 386         }
 387         return res;
 388 }
 389
 390 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 391 {
 392         struct i2c_client *client = file->private_data;
 393         unsigned long funcs;
 394
 395         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 396                 cmd, arg);
 397
 398         switch (cmd) {
 399         case I2C_SLAVE:
 400         case I2C_SLAVE_FORCE:
 401                 /* NOTE:  devices set up to work with "new style" drivers
 402                  * can't use I2C_SLAVE, even when the device node is not
 403                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 404                  *
 405                  * Setting the PEC flag here won't affect kernel drivers,
 406                  * which will be using the i2c_client node registered with
 407                  * the driver model core.  Likewise, when that client has
 408                  * the PEC flag already set, the i2c-dev driver won't see
 409                  * (or use) this setting.
 410                  */
 411                 if ((arg > 0x3ff) ||
 412                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 413                         return -EINVAL;
 414                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 415                         return -EBUSY;
 416                 /* REVISIT: address could become busy later */
 417                 client->addr = arg;
 418                 return 0;
 419         case I2C_TENBIT:
 420                 if (arg)
 421                         client->flags |= I2C_M_TEN;
 422                 else
 423                         client->flags &= ~I2C_M_TEN;
 424                 return 0;
 425         case I2C_PEC:
 426                 if (arg)
 427                         client->flags |= I2C_CLIENT_PEC;
 428                 else
 429                         client->flags &= ~I2C_CLIENT_PEC;
 430                 return 0;
 431         case I2C_FUNCS:
 432                 funcs = i2c_get_functionality(client->adapter);
 433                 return put_user(funcs, (unsigned long __user *)arg);
 434
 435         case I2C_RDWR:
 436                 return i2cdev_ioctl_rdrw(client, arg);
 437
 438         case I2C_SMBUS:
 439                 return i2cdev_ioctl_smbus(client, arg);
 440
 441         case I2C_RETRIES:
 442                 client->adapter->retries = arg;
 443                 break;
 444         case I2C_TIMEOUT:
 445                 /* For historical reasons, user-space sets the timeout
 446                  * value in units of 10 ms.
 447                  */
 448                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 449                 break;
 450         default:
 451                 /* NOTE:  returning a fault code here could cause trouble
 452                  * in buggy userspace code.  Some old kernel bugs returned
 453                  * zero in this case, and userspace code might accidentally
 454                  * have depended on that bug.
 455                  */
 456                 return -ENOTTY;
 457         }
 458         return 0;
 459 }
 460
 461 static int i2cdev_open(struct inode *inode, struct file *file)
 462 {
 463         unsigned int minor = iminor(inode);
 464         struct i2c_client *client;
 465         struct i2c_adapter *adap;
 466         struct i2c_dev *i2c_dev;
 467
 468         i2c_dev = i2c_dev_get_by_minor(minor);
 469         if (!i2c_dev)
 470                 return -ENODEV;
 471
 472         adap = i2c_get_adapter(i2c_dev->adap->nr);
 473         if (!adap)
 474                 return -ENODEV;
 475
 476         /* This creates an anonymous i2c_client, which may later be
 477          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 478          *
 479          * This client is ** NEVER REGISTERED ** with the driver model
 480          * or I2C core code!!  It just holds private copies of addressing
 481          * information and maybe a PEC flag.
 482          */
 483         client = kzalloc(sizeof(*client), GFP_KERNEL);
 484         if (!client) {
 485                 i2c_put_adapter(adap);
 486                 return -ENOMEM;
 487         }
 488         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 489
 490         client->adapter = adap;
 491         file->private_data = client;
 492
 493         return 0;
 494 }
 495
 496 static int i2cdev_release(struct inode *inode, struct file *file)
 497 {
 498         struct i2c_client *client = file->private_data;
 499
 500         i2c_put_adapter(client->adapter);
 501         kfree(client);
 502         file->private_data = NULL;
 503
 504         return 0;
 505 }
 506
 507 static const struct file_operations i2cdev_fops = {
 508         .owner          = THIS_MODULE,
 509         .llseek         = no_llseek,
 510         .read           = i2cdev_read,
 511         .write          = i2cdev_write,
 512         .unlocked_ioctl = i2cdev_ioctl,
 513         .open           = i2cdev_open,
 514         .release        = i2cdev_release,
 515 };
 516
 517 /* ------------------------------------------------------------------------- */
 518
 519 static struct class *i2c_dev_class;
 520
 521 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 522 {
 523         struct i2c_adapter *adap;
 524         struct i2c_dev *i2c_dev;
 525         int res;
 526
 527         if (dev->type != &i2c_adapter_type)
 528                 return 0;
 529         adap = to_i2c_adapter(dev);
 530
 531         i2c_dev = get_free_i2c_dev(adap);
 532         if (IS_ERR(i2c_dev))
 533                 return PTR_ERR(i2c_dev);
 534
 535         /* register this i2c device with the driver core */
 536         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 537                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 538                                      "i2c-%d", adap->nr);
 539         if (IS_ERR(i2c_dev->dev)) {
 540                 res = PTR_ERR(i2c_dev->dev);
 541                 goto error;
 542         }
 543         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 544         if (res)
 545                 goto error_destroy;
 546
 547         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 548                  adap->name, adap->nr);
 549         return 0;
 550 error_destroy:
 551         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 552 error:
 553         return_i2c_dev(i2c_dev);
 554         return res;
 555 }
 556
 557 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 558 {
 559         struct i2c_adapter *adap;
 560         struct i2c_dev *i2c_dev;
 561
 562         if (dev->type != &i2c_adapter_type)
 563                 return 0;
 564         adap = to_i2c_adapter(dev);
 565
 566         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 567         if (!i2c_dev) /* attach_adapter must have failed */
 568                 return 0;
 569
 570         device_remove_file(i2c_dev->dev, &dev_attr_name);
 571         return_i2c_dev(i2c_dev);
 572         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 573
 574         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 575         return 0;
 576 }
 577
 578 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 579                          void *data)
 580 {
 581         struct device *dev = data;
 582
 583         switch (action) {
 584         case BUS_NOTIFY_ADD_DEVICE:
 585                 return i2cdev_attach_adapter(dev, NULL);
 586         case BUS_NOTIFY_DEL_DEVICE:
 587                 return i2cdev_detach_adapter(dev, NULL);
 588         }
 589
 590         return 0;
 591 }
 592
 593 static struct notifier_block i2cdev_notifier = {
 594         .notifier_call = i2cdev_notifier_call,
 595 };
 596
 597 /* ------------------------------------------------------------------------- */
 598
 599 /*
 600  * module load/unload record keeping
 601  */
 602
 603 static int __init i2c_dev_init(void)
 604 {
 605         int res;
 606
 607         printk(KERN_INFO "i2c /dev entries driver\n");
 608
 609         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 610         if (res)
 611                 goto out;
 612
 613         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 614         if (IS_ERR(i2c_dev_class)) {
 615                 res = PTR_ERR(i2c_dev_class);
 616                 goto out_unreg_chrdev;
 617         }
 618
 619         /* Keep track of adapters which will be added or removed later */
 620         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 621         if (res)
 622                 goto out_unreg_class;
 623
 624         /* Bind to already existing adapters right away */
 625         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 626
 627         return 0;
 628
 629 out_unreg_class:
 630         class_destroy(i2c_dev_class);
 631 out_unreg_chrdev:
 632         unregister_chrdev(I2C_MAJOR, "i2c");
 633 out:
 634         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 635         return res;
 636 }
 637
 638 static void __exit i2c_dev_exit(void)
 639 {
 640         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 641         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 642         class_destroy(i2c_dev_class);
 643         unregister_chrdev(I2C_MAJOR, "i2c");
 644 }
 645
 646 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 647                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 648 MODULE_DESCRIPTION("I2C /dev entries driver");
 649 MODULE_LICENSE("GPL");
 650
 651 module_init(i2c_dev_init);
 652 module_exit(i2c_dev_exit);