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_inode(file)), 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_inode(file)), 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                 if (rdwr_pa[i].len > 8192) {
 270                         res = -EINVAL;
 271                         break;
 272                 }
 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                 /*
 282                  * If the message length is received from the slave (similar
 283                  * to SMBus block read), we must ensure that the buffer will
 284                  * be large enough to cope with a message length of
 285                  * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
 286                  * drivers allow. The first byte in the buffer must be
 287                  * pre-filled with the number of extra bytes, which must be
 288                  * at least one to hold the message length, but can be
 289                  * greater (for example to account for a checksum byte at
 290                  * the end of the message.)
 291                  */
 292                 if (rdwr_pa[i].flags & I2C_M_RECV_LEN) {
 293                         if (!(rdwr_pa[i].flags & I2C_M_RD) ||
 294                             rdwr_pa[i].buf[0] < 1 ||
 295                             rdwr_pa[i].len < rdwr_pa[i].buf[0] +
 296                                              I2C_SMBUS_BLOCK_MAX) {
 297                                 res = -EINVAL;
 298                                 break;
 299                         }
 300
 301                         rdwr_pa[i].len = rdwr_pa[i].buf[0];
 302                 }
 303         }
 304         if (res < 0) {
 305                 int j;
 306                 for (j = 0; j < i; ++j)
 307                         kfree(rdwr_pa[j].buf);
 308                 kfree(data_ptrs);
 309                 kfree(rdwr_pa);
 310                 return res;
 311         }
 312
 313         res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 314         while (i-- > 0) {
 315                 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 316                         if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 317                                          rdwr_pa[i].len))
 318                                 res = -EFAULT;
 319                 }
 320                 kfree(rdwr_pa[i].buf);
 321         }
 322         kfree(data_ptrs);
 323         kfree(rdwr_pa);
 324         return res;
 325 }
 326
 327 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 328                 unsigned long arg)
 329 {
 330         struct i2c_smbus_ioctl_data data_arg;
 331         union i2c_smbus_data temp;
 332         int datasize, res;
 333
 334         if (copy_from_user(&data_arg,
 335                            (struct i2c_smbus_ioctl_data __user *) arg,
 336                            sizeof(struct i2c_smbus_ioctl_data)))
 337                 return -EFAULT;
 338         if ((data_arg.size != I2C_SMBUS_BYTE) &&
 339             (data_arg.size != I2C_SMBUS_QUICK) &&
 340             (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 341             (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 342             (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 343             (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 344             (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 345             (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 346             (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 347                 dev_dbg(&client->adapter->dev,
 348                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 349                         data_arg.size);
 350                 return -EINVAL;
 351         }
 352         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 353            so the check is valid if size==I2C_SMBUS_QUICK too. */
 354         if ((data_arg.read_write != I2C_SMBUS_READ) &&
 355             (data_arg.read_write != I2C_SMBUS_WRITE)) {
 356                 dev_dbg(&client->adapter->dev,
 357                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 358                         data_arg.read_write);
 359                 return -EINVAL;
 360         }
 361
 362         /* Note that command values are always valid! */
 363
 364         if ((data_arg.size == I2C_SMBUS_QUICK) ||
 365             ((data_arg.size == I2C_SMBUS_BYTE) &&
 366             (data_arg.read_write == I2C_SMBUS_WRITE)))
 367                 /* These are special: we do not use data */
 368                 return i2c_smbus_xfer(client->adapter, client->addr,
 369                                       client->flags, data_arg.read_write,
 370                                       data_arg.command, data_arg.size, NULL);
 371
 372         if (data_arg.data == NULL) {
 373                 dev_dbg(&client->adapter->dev,
 374                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 375                 return -EINVAL;
 376         }
 377
 378         if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 379             (data_arg.size == I2C_SMBUS_BYTE))
 380                 datasize = sizeof(data_arg.data->byte);
 381         else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 382                  (data_arg.size == I2C_SMBUS_PROC_CALL))
 383                 datasize = sizeof(data_arg.data->word);
 384         else /* size == smbus block, i2c block, or block proc. call */
 385                 datasize = sizeof(data_arg.data->block);
 386
 387         if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 388             (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 389             (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 390             (data_arg.read_write == I2C_SMBUS_WRITE)) {
 391                 if (copy_from_user(&temp, data_arg.data, datasize))
 392                         return -EFAULT;
 393         }
 394         if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 395                 /* Convert old I2C block commands to the new
 396                    convention. This preserves binary compatibility. */
 397                 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 398                 if (data_arg.read_write == I2C_SMBUS_READ)
 399                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 400         }
 401         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 402               data_arg.read_write, data_arg.command, data_arg.size, &temp);
 403         if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 404                      (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 405                      (data_arg.read_write == I2C_SMBUS_READ))) {
 406                 if (copy_to_user(data_arg.data, &temp, datasize))
 407                         return -EFAULT;
 408         }
 409         return res;
 410 }
 411
 412 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 413 {
 414         struct i2c_client *client = file->private_data;
 415         unsigned long funcs;
 416
 417         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 418                 cmd, arg);
 419
 420         switch (cmd) {
 421         case I2C_SLAVE:
 422         case I2C_SLAVE_FORCE:
 423                 /* NOTE:  devices set up to work with "new style" drivers
 424                  * can't use I2C_SLAVE, even when the device node is not
 425                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 426                  *
 427                  * Setting the PEC flag here won't affect kernel drivers,
 428                  * which will be using the i2c_client node registered with
 429                  * the driver model core.  Likewise, when that client has
 430                  * the PEC flag already set, the i2c-dev driver won't see
 431                  * (or use) this setting.
 432                  */
 433                 if ((arg > 0x3ff) ||
 434                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 435                         return -EINVAL;
 436                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 437                         return -EBUSY;
 438                 /* REVISIT: address could become busy later */
 439                 client->addr = arg;
 440                 return 0;
 441         case I2C_TENBIT:
 442                 if (arg)
 443                         client->flags |= I2C_M_TEN;
 444                 else
 445                         client->flags &= ~I2C_M_TEN;
 446                 return 0;
 447         case I2C_PEC:
 448                 if (arg)
 449                         client->flags |= I2C_CLIENT_PEC;
 450                 else
 451                         client->flags &= ~I2C_CLIENT_PEC;
 452                 return 0;
 453         case I2C_FUNCS:
 454                 funcs = i2c_get_functionality(client->adapter);
 455                 return put_user(funcs, (unsigned long __user *)arg);
 456
 457         case I2C_RDWR:
 458                 return i2cdev_ioctl_rdrw(client, arg);
 459
 460         case I2C_SMBUS:
 461                 return i2cdev_ioctl_smbus(client, arg);
 462
 463         case I2C_RETRIES:
 464                 client->adapter->retries = arg;
 465                 break;
 466         case I2C_TIMEOUT:
 467                 /* For historical reasons, user-space sets the timeout
 468                  * value in units of 10 ms.
 469                  */
 470                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 471                 break;
 472         default:
 473                 /* NOTE:  returning a fault code here could cause trouble
 474                  * in buggy userspace code.  Some old kernel bugs returned
 475                  * zero in this case, and userspace code might accidentally
 476                  * have depended on that bug.
 477                  */
 478                 return -ENOTTY;
 479         }
 480         return 0;
 481 }
 482
 483 static int i2cdev_open(struct inode *inode, struct file *file)
 484 {
 485         unsigned int minor = iminor(inode);
 486         struct i2c_client *client;
 487         struct i2c_adapter *adap;
 488         struct i2c_dev *i2c_dev;
 489
 490         i2c_dev = i2c_dev_get_by_minor(minor);
 491         if (!i2c_dev)
 492                 return -ENODEV;
 493
 494         adap = i2c_get_adapter(i2c_dev->adap->nr);
 495         if (!adap)
 496                 return -ENODEV;
 497
 498         /* This creates an anonymous i2c_client, which may later be
 499          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 500          *
 501          * This client is ** NEVER REGISTERED ** with the driver model
 502          * or I2C core code!!  It just holds private copies of addressing
 503          * information and maybe a PEC flag.
 504          */
 505         client = kzalloc(sizeof(*client), GFP_KERNEL);
 506         if (!client) {
 507                 i2c_put_adapter(adap);
 508                 return -ENOMEM;
 509         }
 510         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 511
 512         client->adapter = adap;
 513         file->private_data = client;
 514
 515         return 0;
 516 }
 517
 518 static int i2cdev_release(struct inode *inode, struct file *file)
 519 {
 520         struct i2c_client *client = file->private_data;
 521
 522         i2c_put_adapter(client->adapter);
 523         kfree(client);
 524         file->private_data = NULL;
 525
 526         return 0;
 527 }
 528
 529 static const struct file_operations i2cdev_fops = {
 530         .owner          = THIS_MODULE,
 531         .llseek         = no_llseek,
 532         .read           = i2cdev_read,
 533         .write          = i2cdev_write,
 534         .unlocked_ioctl = i2cdev_ioctl,
 535         .open           = i2cdev_open,
 536         .release        = i2cdev_release,
 537 };
 538
 539 /* ------------------------------------------------------------------------- */
 540
 541 static struct class *i2c_dev_class;
 542
 543 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 544 {
 545         struct i2c_adapter *adap;
 546         struct i2c_dev *i2c_dev;
 547         int res;
 548
 549         if (dev->type != &i2c_adapter_type)
 550                 return 0;
 551         adap = to_i2c_adapter(dev);
 552
 553         i2c_dev = get_free_i2c_dev(adap);
 554         if (IS_ERR(i2c_dev))
 555                 return PTR_ERR(i2c_dev);
 556
 557         /* register this i2c device with the driver core */
 558         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 559                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 560                                      "i2c-%d", adap->nr);
 561         if (IS_ERR(i2c_dev->dev)) {
 562                 res = PTR_ERR(i2c_dev->dev);
 563                 goto error;
 564         }
 565         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 566         if (res)
 567                 goto error_destroy;
 568
 569         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 570                  adap->name, adap->nr);
 571         return 0;
 572 error_destroy:
 573         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 574 error:
 575         return_i2c_dev(i2c_dev);
 576         return res;
 577 }
 578
 579 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 580 {
 581         struct i2c_adapter *adap;
 582         struct i2c_dev *i2c_dev;
 583
 584         if (dev->type != &i2c_adapter_type)
 585                 return 0;
 586         adap = to_i2c_adapter(dev);
 587
 588         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 589         if (!i2c_dev) /* attach_adapter must have failed */
 590                 return 0;
 591
 592         device_remove_file(i2c_dev->dev, &dev_attr_name);
 593         return_i2c_dev(i2c_dev);
 594         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 595
 596         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 597         return 0;
 598 }
 599
 600 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 601                          void *data)
 602 {
 603         struct device *dev = data;
 604
 605         switch (action) {
 606         case BUS_NOTIFY_ADD_DEVICE:
 607                 return i2cdev_attach_adapter(dev, NULL);
 608         case BUS_NOTIFY_DEL_DEVICE:
 609                 return i2cdev_detach_adapter(dev, NULL);
 610         }
 611
 612         return 0;
 613 }
 614
 615 static struct notifier_block i2cdev_notifier = {
 616         .notifier_call = i2cdev_notifier_call,
 617 };
 618
 619 /* ------------------------------------------------------------------------- */
 620
 621 /*
 622  * module load/unload record keeping
 623  */
 624
 625 static int __init i2c_dev_init(void)
 626 {
 627         int res;
 628
 629         printk(KERN_INFO "i2c /dev entries driver\n");
 630
 631         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 632         if (res)
 633                 goto out;
 634
 635         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 636         if (IS_ERR(i2c_dev_class)) {
 637                 res = PTR_ERR(i2c_dev_class);
 638                 goto out_unreg_chrdev;
 639         }
 640
 641         /* Keep track of adapters which will be added or removed later */
 642         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 643         if (res)
 644                 goto out_unreg_class;
 645
 646         /* Bind to already existing adapters right away */
 647         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 648
 649         return 0;
 650
 651 out_unreg_class:
 652         class_destroy(i2c_dev_class);
 653 out_unreg_chrdev:
 654         unregister_chrdev(I2C_MAJOR, "i2c");
 655 out:
 656         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 657         return res;
 658 }
 659
 660 static void __exit i2c_dev_exit(void)
 661 {
 662         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 663         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 664         class_destroy(i2c_dev_class);
 665         unregister_chrdev(I2C_MAJOR, "i2c");
 666 }
 667
 668 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 669                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 670 MODULE_DESCRIPTION("I2C /dev entries driver");
 671 MODULE_LICENSE("GPL");
 672
 673 module_init(i2c_dev_init);
 674 module_exit(i2c_dev_exit);