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
  19 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
  20    But I have used so much of his original code and ideas that it seems
  21    only fair to recognize him as co-author -- Frodo */
  22
  23 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
  24
  25 #include <linux/cdev.h>
  26 #include <linux/device.h>
  27 #include <linux/fs.h>
  28 #include <linux/i2c-dev.h>
  29 #include <linux/i2c.h>
  30 #include <linux/init.h>
  31 #include <linux/jiffies.h>
  32 #include <linux/kernel.h>
  33 #include <linux/list.h>
  34 #include <linux/module.h>
  35 #include <linux/notifier.h>
  36 #include <linux/slab.h>
  37 #include <linux/uaccess.h>
  38
  39 /*
  40  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  41  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  42  * with a character special file which is accessed by user mode drivers.
  43  *
  44  * The list of i2c_dev structures is parallel to the i2c_adapter lists
  45  * maintained by the driver model, and is updated using bus notifications.
  46  */
  47 struct i2c_dev {
  48         struct list_head list;
  49         struct i2c_adapter *adap;
  50         struct device *dev;
  51         struct cdev cdev;
  52 };
  53
  54 #define I2C_MINORS      MINORMASK
  55 static LIST_HEAD(i2c_dev_list);
  56 static DEFINE_SPINLOCK(i2c_dev_list_lock);
  57
  58 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
  59 {
  60         struct i2c_dev *i2c_dev;
  61
  62         spin_lock(&i2c_dev_list_lock);
  63         list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
  64                 if (i2c_dev->adap->nr == index)
  65                         goto found;
  66         }
  67         i2c_dev = NULL;
  68 found:
  69         spin_unlock(&i2c_dev_list_lock);
  70         return i2c_dev;
  71 }
  72
  73 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
  74 {
  75         struct i2c_dev *i2c_dev;
  76
  77         if (adap->nr >= I2C_MINORS) {
  78                 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
  79                        adap->nr);
  80                 return ERR_PTR(-ENODEV);
  81         }
  82
  83         i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
  84         if (!i2c_dev)
  85                 return ERR_PTR(-ENOMEM);
  86         i2c_dev->adap = adap;
  87
  88         spin_lock(&i2c_dev_list_lock);
  89         list_add_tail(&i2c_dev->list, &i2c_dev_list);
  90         spin_unlock(&i2c_dev_list_lock);
  91         return i2c_dev;
  92 }
  93
  94 static void put_i2c_dev(struct i2c_dev *i2c_dev)
  95 {
  96         spin_lock(&i2c_dev_list_lock);
  97         list_del(&i2c_dev->list);
  98         spin_unlock(&i2c_dev_list_lock);
  99         kfree(i2c_dev);
 100 }
 101
 102 static ssize_t name_show(struct device *dev,
 103                          struct device_attribute *attr, char *buf)
 104 {
 105         struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
 106
 107         if (!i2c_dev)
 108                 return -ENODEV;
 109         return sprintf(buf, "%s\n", i2c_dev->adap->name);
 110 }
 111 static DEVICE_ATTR_RO(name);
 112
 113 static struct attribute *i2c_attrs[] = {
 114         &dev_attr_name.attr,
 115         NULL,
 116 };
 117 ATTRIBUTE_GROUPS(i2c);
 118
 119 /* ------------------------------------------------------------------------- */
 120
 121 /*
 122  * After opening an instance of this character special file, a file
 123  * descriptor starts out associated only with an i2c_adapter (and bus).
 124  *
 125  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
 126  * traffic to any devices on the bus used by that adapter.  That's because
 127  * the i2c_msg vectors embed all the addressing information they need, and
 128  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
 129  * don't support that interface.
 130  *
 131  * To use read()/write() system calls on that file descriptor, or to use
 132  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
 133  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
 134  * (never registered) i2c_client so it holds the addressing information
 135  * needed by those system calls and by this SMBus interface.
 136  */
 137
 138 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
 139                 loff_t *offset)
 140 {
 141         char *tmp;
 142         int ret;
 143
 144         struct i2c_client *client = file->private_data;
 145
 146         if (count > 8192)
 147                 count = 8192;
 148
 149         tmp = kmalloc(count, GFP_KERNEL);
 150         if (tmp == NULL)
 151                 return -ENOMEM;
 152
 153         pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
 154                 iminor(file_inode(file)), count);
 155
 156         ret = i2c_master_recv(client, tmp, count);
 157         if (ret >= 0)
 158                 ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
 159         kfree(tmp);
 160         return ret;
 161 }
 162
 163 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
 164                 size_t count, loff_t *offset)
 165 {
 166         int ret;
 167         char *tmp;
 168         struct i2c_client *client = file->private_data;
 169
 170         if (count > 8192)
 171                 count = 8192;
 172
 173         tmp = memdup_user(buf, count);
 174         if (IS_ERR(tmp))
 175                 return PTR_ERR(tmp);
 176
 177         pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 178                 iminor(file_inode(file)), count);
 179
 180         ret = i2c_master_send(client, tmp, count);
 181         kfree(tmp);
 182         return ret;
 183 }
 184
 185 static int i2cdev_check(struct device *dev, void *addrp)
 186 {
 187         struct i2c_client *client = i2c_verify_client(dev);
 188
 189         if (!client || client->addr != *(unsigned int *)addrp)
 190                 return 0;
 191
 192         return dev->driver ? -EBUSY : 0;
 193 }
 194
 195 /* walk up mux tree */
 196 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 197 {
 198         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 199         int result;
 200
 201         result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 202         if (!result && parent)
 203                 result = i2cdev_check_mux_parents(parent, addr);
 204
 205         return result;
 206 }
 207
 208 /* recurse down mux tree */
 209 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 210 {
 211         int result;
 212
 213         if (dev->type == &i2c_adapter_type)
 214                 result = device_for_each_child(dev, addrp,
 215                                                 i2cdev_check_mux_children);
 216         else
 217                 result = i2cdev_check(dev, addrp);
 218
 219         return result;
 220 }
 221
 222 /* This address checking function differs from the one in i2c-core
 223    in that it considers an address with a registered device, but no
 224    driver bound to it, as NOT busy. */
 225 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 226 {
 227         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 228         int result = 0;
 229
 230         if (parent)
 231                 result = i2cdev_check_mux_parents(parent, addr);
 232
 233         if (!result)
 234                 result = device_for_each_child(&adapter->dev, &addr,
 235                                                 i2cdev_check_mux_children);
 236
 237         return result;
 238 }
 239
 240 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
 241                 unsigned long arg)
 242 {
 243         struct i2c_rdwr_ioctl_data rdwr_arg;
 244         struct i2c_msg *rdwr_pa;
 245         u8 __user **data_ptrs;
 246         int i, res;
 247
 248         if (copy_from_user(&rdwr_arg,
 249                            (struct i2c_rdwr_ioctl_data __user *)arg,
 250                            sizeof(rdwr_arg)))
 251                 return -EFAULT;
 252
 253         /* Put an arbitrary limit on the number of messages that can
 254          * be sent at once */
 255         if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 256                 return -EINVAL;
 257
 258         rdwr_pa = memdup_user(rdwr_arg.msgs,
 259                               rdwr_arg.nmsgs * sizeof(struct i2c_msg));
 260         if (IS_ERR(rdwr_pa))
 261                 return PTR_ERR(rdwr_pa);
 262
 263         data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 264         if (data_ptrs == NULL) {
 265                 kfree(rdwr_pa);
 266                 return -ENOMEM;
 267         }
 268
 269         res = 0;
 270         for (i = 0; i < rdwr_arg.nmsgs; i++) {
 271                 /* Limit the size of the message to a sane amount */
 272                 if (rdwr_pa[i].len > 8192) {
 273                         res = -EINVAL;
 274                         break;
 275                 }
 276
 277                 data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 278                 rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
 279                 if (IS_ERR(rdwr_pa[i].buf)) {
 280                         res = PTR_ERR(rdwr_pa[i].buf);
 281                         break;
 282                 }
 283
 284                 /*
 285                  * If the message length is received from the slave (similar
 286                  * to SMBus block read), we must ensure that the buffer will
 287                  * be large enough to cope with a message length of
 288                  * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
 289                  * drivers allow. The first byte in the buffer must be
 290                  * pre-filled with the number of extra bytes, which must be
 291                  * at least one to hold the message length, but can be
 292                  * greater (for example to account for a checksum byte at
 293                  * the end of the message.)
 294                  */
 295                 if (rdwr_pa[i].flags & I2C_M_RECV_LEN) {
 296                         if (!(rdwr_pa[i].flags & I2C_M_RD) ||
 297                             rdwr_pa[i].buf[0] < 1 ||
 298                             rdwr_pa[i].len < rdwr_pa[i].buf[0] +
 299                                              I2C_SMBUS_BLOCK_MAX) {
 300                                 res = -EINVAL;
 301                                 break;
 302                         }
 303
 304                         rdwr_pa[i].len = rdwr_pa[i].buf[0];
 305                 }
 306         }
 307         if (res < 0) {
 308                 int j;
 309                 for (j = 0; j < i; ++j)
 310                         kfree(rdwr_pa[j].buf);
 311                 kfree(data_ptrs);
 312                 kfree(rdwr_pa);
 313                 return res;
 314         }
 315
 316         res = i2c_transfer(client->adapter, rdwr_pa, rdwr_arg.nmsgs);
 317         while (i-- > 0) {
 318                 if (res >= 0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 319                         if (copy_to_user(data_ptrs[i], rdwr_pa[i].buf,
 320                                          rdwr_pa[i].len))
 321                                 res = -EFAULT;
 322                 }
 323                 kfree(rdwr_pa[i].buf);
 324         }
 325         kfree(data_ptrs);
 326         kfree(rdwr_pa);
 327         return res;
 328 }
 329
 330 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 331                 unsigned long arg)
 332 {
 333         struct i2c_smbus_ioctl_data data_arg;
 334         union i2c_smbus_data temp;
 335         int datasize, res;
 336
 337         if (copy_from_user(&data_arg,
 338                            (struct i2c_smbus_ioctl_data __user *) arg,
 339                            sizeof(struct i2c_smbus_ioctl_data)))
 340                 return -EFAULT;
 341         if ((data_arg.size != I2C_SMBUS_BYTE) &&
 342             (data_arg.size != I2C_SMBUS_QUICK) &&
 343             (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 344             (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 345             (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 346             (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 347             (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 348             (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 349             (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 350                 dev_dbg(&client->adapter->dev,
 351                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 352                         data_arg.size);
 353                 return -EINVAL;
 354         }
 355         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 356            so the check is valid if size==I2C_SMBUS_QUICK too. */
 357         if ((data_arg.read_write != I2C_SMBUS_READ) &&
 358             (data_arg.read_write != I2C_SMBUS_WRITE)) {
 359                 dev_dbg(&client->adapter->dev,
 360                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 361                         data_arg.read_write);
 362                 return -EINVAL;
 363         }
 364
 365         /* Note that command values are always valid! */
 366
 367         if ((data_arg.size == I2C_SMBUS_QUICK) ||
 368             ((data_arg.size == I2C_SMBUS_BYTE) &&
 369             (data_arg.read_write == I2C_SMBUS_WRITE)))
 370                 /* These are special: we do not use data */
 371                 return i2c_smbus_xfer(client->adapter, client->addr,
 372                                       client->flags, data_arg.read_write,
 373                                       data_arg.command, data_arg.size, NULL);
 374
 375         if (data_arg.data == NULL) {
 376                 dev_dbg(&client->adapter->dev,
 377                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 378                 return -EINVAL;
 379         }
 380
 381         if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 382             (data_arg.size == I2C_SMBUS_BYTE))
 383                 datasize = sizeof(data_arg.data->byte);
 384         else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 385                  (data_arg.size == I2C_SMBUS_PROC_CALL))
 386                 datasize = sizeof(data_arg.data->word);
 387         else /* size == smbus block, i2c block, or block proc. call */
 388                 datasize = sizeof(data_arg.data->block);
 389
 390         if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 391             (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 392             (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 393             (data_arg.read_write == I2C_SMBUS_WRITE)) {
 394                 if (copy_from_user(&temp, data_arg.data, datasize))
 395                         return -EFAULT;
 396         }
 397         if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 398                 /* Convert old I2C block commands to the new
 399                    convention. This preserves binary compatibility. */
 400                 data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 401                 if (data_arg.read_write == I2C_SMBUS_READ)
 402                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 403         }
 404         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 405               data_arg.read_write, data_arg.command, data_arg.size, &temp);
 406         if (!res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 407                      (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 408                      (data_arg.read_write == I2C_SMBUS_READ))) {
 409                 if (copy_to_user(data_arg.data, &temp, datasize))
 410                         return -EFAULT;
 411         }
 412         return res;
 413 }
 414
 415 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 416 {
 417         struct i2c_client *client = file->private_data;
 418         unsigned long funcs;
 419
 420         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 421                 cmd, arg);
 422
 423         switch (cmd) {
 424         case I2C_SLAVE:
 425         case I2C_SLAVE_FORCE:
 426                 if ((arg > 0x3ff) ||
 427                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 428                         return -EINVAL;
 429                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 430                         return -EBUSY;
 431                 /* REVISIT: address could become busy later */
 432                 client->addr = arg;
 433                 return 0;
 434         case I2C_TENBIT:
 435                 if (arg)
 436                         client->flags |= I2C_M_TEN;
 437                 else
 438                         client->flags &= ~I2C_M_TEN;
 439                 return 0;
 440         case I2C_PEC:
 441                 /*
 442                  * Setting the PEC flag here won't affect kernel drivers,
 443                  * which will be using the i2c_client node registered with
 444                  * the driver model core.  Likewise, when that client has
 445                  * the PEC flag already set, the i2c-dev driver won't see
 446                  * (or use) this setting.
 447                  */
 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_rdwr(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         cdev_init(&i2c_dev->cdev, &i2cdev_fops);
 558         i2c_dev->cdev.owner = THIS_MODULE;
 559         res = cdev_add(&i2c_dev->cdev, MKDEV(I2C_MAJOR, adap->nr), 1);
 560         if (res)
 561                 goto error_cdev;
 562
 563         /* register this i2c device with the driver core */
 564         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 565                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 566                                      "i2c-%d", adap->nr);
 567         if (IS_ERR(i2c_dev->dev)) {
 568                 res = PTR_ERR(i2c_dev->dev);
 569                 goto error;
 570         }
 571
 572         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 573                  adap->name, adap->nr);
 574         return 0;
 575 error:
 576         cdev_del(&i2c_dev->cdev);
 577 error_cdev:
 578         put_i2c_dev(i2c_dev);
 579         return res;
 580 }
 581
 582 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 583 {
 584         struct i2c_adapter *adap;
 585         struct i2c_dev *i2c_dev;
 586
 587         if (dev->type != &i2c_adapter_type)
 588                 return 0;
 589         adap = to_i2c_adapter(dev);
 590
 591         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 592         if (!i2c_dev) /* attach_adapter must have failed */
 593                 return 0;
 594
 595         cdev_del(&i2c_dev->cdev);
 596         put_i2c_dev(i2c_dev);
 597         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 598
 599         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 600         return 0;
 601 }
 602
 603 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 604                          void *data)
 605 {
 606         struct device *dev = data;
 607
 608         switch (action) {
 609         case BUS_NOTIFY_ADD_DEVICE:
 610                 return i2cdev_attach_adapter(dev, NULL);
 611         case BUS_NOTIFY_DEL_DEVICE:
 612                 return i2cdev_detach_adapter(dev, NULL);
 613         }
 614
 615         return 0;
 616 }
 617
 618 static struct notifier_block i2cdev_notifier = {
 619         .notifier_call = i2cdev_notifier_call,
 620 };
 621
 622 /* ------------------------------------------------------------------------- */
 623
 624 /*
 625  * module load/unload record keeping
 626  */
 627
 628 static int __init i2c_dev_init(void)
 629 {
 630         int res;
 631
 632         printk(KERN_INFO "i2c /dev entries driver\n");
 633
 634         res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
 635         if (res)
 636                 goto out;
 637
 638         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 639         if (IS_ERR(i2c_dev_class)) {
 640                 res = PTR_ERR(i2c_dev_class);
 641                 goto out_unreg_chrdev;
 642         }
 643         i2c_dev_class->dev_groups = i2c_groups;
 644
 645         /* Keep track of adapters which will be added or removed later */
 646         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 647         if (res)
 648                 goto out_unreg_class;
 649
 650         /* Bind to already existing adapters right away */
 651         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 652
 653         return 0;
 654
 655 out_unreg_class:
 656         class_destroy(i2c_dev_class);
 657 out_unreg_chrdev:
 658         unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 659 out:
 660         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 661         return res;
 662 }
 663
 664 static void __exit i2c_dev_exit(void)
 665 {
 666         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 667         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 668         class_destroy(i2c_dev_class);
 669         unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 670 }
 671
 672 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 673                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 674 MODULE_DESCRIPTION("I2C /dev entries driver");
 675 MODULE_LICENSE("GPL");
 676
 677 module_init(i2c_dev_init);
 678 module_exit(i2c_dev_exit);