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 = kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg), GFP_KERNEL);
 255         if (!rdwr_pa)
 256                 return -ENOMEM;
 257
 258         if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
 259                            rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
 260                 kfree(rdwr_pa);
 261                 return -EFAULT;
 262         }
 263
 264         data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 265         if (data_ptrs == NULL) {
 266                 kfree(rdwr_pa);
 267                 return -ENOMEM;
 268         }
 269
 270         res = 0;
 271         for (i = 0; i < rdwr_arg.nmsgs; i++) {
 272                 /* Limit the size of the message to a sane amount;
 273                  * and don't let length change either. */
 274                 if ((rdwr_pa[i].len > 8192) ||
 275                     (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 276                         res = -EINVAL;
 277                         break;
 278                 }
 279                 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 280                 rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
 281                 if (IS_ERR(rdwr_pa[i].buf)) {
 282                         res = PTR_ERR(rdwr_pa[i].buf);
 283                         break;
 284                 }
 285         }
 286         if (res < 0) {
 287                 int j;
 288                 for (j = 0; j < i; ++j)
 289                         kfree(rdwr_pa[j].buf);
 290                 kfree(data_ptrs);
 291                 kfree(rdwr_pa);
 292                 return res;
 293         }
 294
 295         res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 296         while (i-- > 0) {
 297                 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 298                         if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 299                                          rdwr_pa[i].len))
 300                                 res = -EFAULT;
 301                 }
 302                 kfree(rdwr_pa[i].buf);
 303         }
 304         kfree(data_ptrs);
 305         kfree(rdwr_pa);
 306         return res;
 307 }
 308
 309 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 310                 unsigned long arg)
 311 {
 312         struct i2c_smbus_ioctl_data data_arg;
 313         union i2c_smbus_data temp;
 314         int datasize, res;
 315
 316         if (copy_from_user(&data_arg,
 317                            (struct i2c_smbus_ioctl_data __user *) arg,
 318                            sizeof(struct i2c_smbus_ioctl_data)))
 319                 return -EFAULT;
 320         if ((data_arg.size != I2C_SMBUS_BYTE) &&
 321             (data_arg.size != I2C_SMBUS_QUICK) &&
 322             (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 323             (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 324             (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 325             (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 326             (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 327             (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 328             (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 329                 dev_dbg(&client->adapter->dev,
 330                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 331                         data_arg.size);
 332                 return -EINVAL;
 333         }
 334         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 335            so the check is valid if size==I2C_SMBUS_QUICK too. */
 336         if ((data_arg.read_write != I2C_SMBUS_READ) &&
 337             (data_arg.read_write != I2C_SMBUS_WRITE)) {
 338                 dev_dbg(&client->adapter->dev,
 339                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 340                         data_arg.read_write);
 341                 return -EINVAL;
 342         }
 343
 344         /* Note that command values are always valid! */
 345
 346         if ((data_arg.size == I2C_SMBUS_QUICK) ||
 347             ((data_arg.size == I2C_SMBUS_BYTE) &&
 348             (data_arg.read_write == I2C_SMBUS_WRITE)))
 349                 /* These are special: we do not use data */
 350                 return i2c_smbus_xfer(client->adapter, client->addr,
 351                                       client->flags, data_arg.read_write,
 352                                       data_arg.command, data_arg.size, NULL);
 353
 354         if (data_arg.data == NULL) {
 355                 dev_dbg(&client->adapter->dev,
 356                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 357                 return -EINVAL;
 358         }
 359
 360         if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 361             (data_arg.size == I2C_SMBUS_BYTE))
 362                 datasize = sizeof(data_arg.data->byte);
 363         else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 364                  (data_arg.size == I2C_SMBUS_PROC_CALL))
 365                 datasize = sizeof(data_arg.data->word);
 366         else /* size == smbus block, i2c block, or block proc. call */
 367                 datasize = sizeof(data_arg.data->block);
 368
 369         if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 370             (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 371             (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 372             (data_arg.read_write == I2C_SMBUS_WRITE)) {
 373                 if (copy_from_user(&temp, data_arg.data, datasize))
 374                         return -EFAULT;
 375         }
 376         if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 377                 /* Convert old I2C block commands to the new
 378                    convention. This preserves binary compatibility. */
 379                 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 380                 if (data_arg.read_write == I2C_SMBUS_READ)
 381                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 382         }
 383         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 384               data_arg.read_write, data_arg.command, data_arg.size, &temp);
 385         if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 386                      (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 387                      (data_arg.read_write == I2C_SMBUS_READ))) {
 388                 if (copy_to_user(data_arg.data, &temp, datasize))
 389                         return -EFAULT;
 390         }
 391         return res;
 392 }
 393
 394 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 395 {
 396         struct i2c_client *client = file->private_data;
 397         unsigned long funcs;
 398
 399         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 400                 cmd, arg);
 401
 402         switch (cmd) {
 403         case I2C_SLAVE:
 404         case I2C_SLAVE_FORCE:
 405                 /* NOTE:  devices set up to work with "new style" drivers
 406                  * can't use I2C_SLAVE, even when the device node is not
 407                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 408                  *
 409                  * Setting the PEC flag here won't affect kernel drivers,
 410                  * which will be using the i2c_client node registered with
 411                  * the driver model core.  Likewise, when that client has
 412                  * the PEC flag already set, the i2c-dev driver won't see
 413                  * (or use) this setting.
 414                  */
 415                 if ((arg > 0x3ff) ||
 416                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 417                         return -EINVAL;
 418                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 419                         return -EBUSY;
 420                 /* REVISIT: address could become busy later */
 421                 client->addr = arg;
 422                 return 0;
 423         case I2C_TENBIT:
 424                 if (arg)
 425                         client->flags |= I2C_M_TEN;
 426                 else
 427                         client->flags &= ~I2C_M_TEN;
 428                 return 0;
 429         case I2C_PEC:
 430                 if (arg)
 431                         client->flags |= I2C_CLIENT_PEC;
 432                 else
 433                         client->flags &= ~I2C_CLIENT_PEC;
 434                 return 0;
 435         case I2C_FUNCS:
 436                 funcs = i2c_get_functionality(client->adapter);
 437                 return put_user(funcs, (unsigned long __user *)arg);
 438
 439         case I2C_RDWR:
 440                 return i2cdev_ioctl_rdrw(client, arg);
 441
 442         case I2C_SMBUS:
 443                 return i2cdev_ioctl_smbus(client, arg);
 444
 445         case I2C_RETRIES:
 446                 client->adapter->retries = arg;
 447                 break;
 448         case I2C_TIMEOUT:
 449                 /* For historical reasons, user-space sets the timeout
 450                  * value in units of 10 ms.
 451                  */
 452                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 453                 break;
 454         default:
 455                 /* NOTE:  returning a fault code here could cause trouble
 456                  * in buggy userspace code.  Some old kernel bugs returned
 457                  * zero in this case, and userspace code might accidentally
 458                  * have depended on that bug.
 459                  */
 460                 return -ENOTTY;
 461         }
 462         return 0;
 463 }
 464
 465 static int i2cdev_open(struct inode *inode, struct file *file)
 466 {
 467         unsigned int minor = iminor(inode);
 468         struct i2c_client *client;
 469         struct i2c_adapter *adap;
 470         struct i2c_dev *i2c_dev;
 471
 472         i2c_dev = i2c_dev_get_by_minor(minor);
 473         if (!i2c_dev)
 474                 return -ENODEV;
 475
 476         adap = i2c_get_adapter(i2c_dev->adap->nr);
 477         if (!adap)
 478                 return -ENODEV;
 479
 480         /* This creates an anonymous i2c_client, which may later be
 481          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 482          *
 483          * This client is ** NEVER REGISTERED ** with the driver model
 484          * or I2C core code!!  It just holds private copies of addressing
 485          * information and maybe a PEC flag.
 486          */
 487         client = kzalloc(sizeof(*client), GFP_KERNEL);
 488         if (!client) {
 489                 i2c_put_adapter(adap);
 490                 return -ENOMEM;
 491         }
 492         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 493
 494         client->adapter = adap;
 495         file->private_data = client;
 496
 497         return 0;
 498 }
 499
 500 static int i2cdev_release(struct inode *inode, struct file *file)
 501 {
 502         struct i2c_client *client = file->private_data;
 503
 504         i2c_put_adapter(client->adapter);
 505         kfree(client);
 506         file->private_data = NULL;
 507
 508         return 0;
 509 }
 510
 511 static const struct file_operations i2cdev_fops = {
 512         .owner          = THIS_MODULE,
 513         .llseek         = no_llseek,
 514         .read           = i2cdev_read,
 515         .write          = i2cdev_write,
 516         .unlocked_ioctl = i2cdev_ioctl,
 517         .open           = i2cdev_open,
 518         .release        = i2cdev_release,
 519 };
 520
 521 /* ------------------------------------------------------------------------- */
 522
 523 static struct class *i2c_dev_class;
 524
 525 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 526 {
 527         struct i2c_adapter *adap;
 528         struct i2c_dev *i2c_dev;
 529         int res;
 530
 531         if (dev->type != &i2c_adapter_type)
 532                 return 0;
 533         adap = to_i2c_adapter(dev);
 534
 535         i2c_dev = get_free_i2c_dev(adap);
 536         if (IS_ERR(i2c_dev))
 537                 return PTR_ERR(i2c_dev);
 538
 539         /* register this i2c device with the driver core */
 540         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 541                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 542                                      "i2c-%d", adap->nr);
 543         if (IS_ERR(i2c_dev->dev)) {
 544                 res = PTR_ERR(i2c_dev->dev);
 545                 goto error;
 546         }
 547         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 548         if (res)
 549                 goto error_destroy;
 550
 551         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 552                  adap->name, adap->nr);
 553         return 0;
 554 error_destroy:
 555         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 556 error:
 557         return_i2c_dev(i2c_dev);
 558         return res;
 559 }
 560
 561 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 562 {
 563         struct i2c_adapter *adap;
 564         struct i2c_dev *i2c_dev;
 565
 566         if (dev->type != &i2c_adapter_type)
 567                 return 0;
 568         adap = to_i2c_adapter(dev);
 569
 570         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 571         if (!i2c_dev) /* attach_adapter must have failed */
 572                 return 0;
 573
 574         device_remove_file(i2c_dev->dev, &dev_attr_name);
 575         return_i2c_dev(i2c_dev);
 576         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 577
 578         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 579         return 0;
 580 }
 581
 582 int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 583                          void *data)
 584 {
 585         struct device *dev = data;
 586
 587         switch (action) {
 588         case BUS_NOTIFY_ADD_DEVICE:
 589                 return i2cdev_attach_adapter(dev, NULL);
 590         case BUS_NOTIFY_DEL_DEVICE:
 591                 return i2cdev_detach_adapter(dev, NULL);
 592         }
 593
 594         return 0;
 595 }
 596
 597 static struct notifier_block i2cdev_notifier = {
 598         .notifier_call = i2cdev_notifier_call,
 599 };
 600
 601 /* ------------------------------------------------------------------------- */
 602
 603 /*
 604  * module load/unload record keeping
 605  */
 606
 607 static int __init i2c_dev_init(void)
 608 {
 609         int res;
 610
 611         printk(KERN_INFO "i2c /dev entries driver\n");
 612
 613         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 614         if (res)
 615                 goto out;
 616
 617         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 618         if (IS_ERR(i2c_dev_class)) {
 619                 res = PTR_ERR(i2c_dev_class);
 620                 goto out_unreg_chrdev;
 621         }
 622
 623         /* Keep track of adapters which will be added or removed later */
 624         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 625         if (res)
 626                 goto out_unreg_class;
 627
 628         /* Bind to already existing adapters right away */
 629         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 630
 631         return 0;
 632
 633 out_unreg_class:
 634         class_destroy(i2c_dev_class);
 635 out_unreg_chrdev:
 636         unregister_chrdev(I2C_MAJOR, "i2c");
 637 out:
 638         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 639         return res;
 640 }
 641
 642 static void __exit i2c_dev_exit(void)
 643 {
 644         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 645         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 646         class_destroy(i2c_dev_class);
 647         unregister_chrdev(I2C_MAJOR, "i2c");
 648 }
 649
 650 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 651                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 652 MODULE_DESCRIPTION("I2C /dev entries driver");
 653 MODULE_LICENSE("GPL");
 654
 655 module_init(i2c_dev_init);
 656 module_exit(i2c_dev_exit);