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 #include <linux/compat.h>
  39
  40 /*
  41  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  42  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  43  * with a character special file which is accessed by user mode drivers.
  44  *
  45  * The list of i2c_dev structures is parallel to the i2c_adapter lists
  46  * maintained by the driver model, and is updated using bus notifications.
  47  */
  48 struct i2c_dev {
  49         struct list_head list;
  50         struct i2c_adapter *adap;
  51         struct device *dev;
  52         struct cdev cdev;
  53 };
  54
  55 #define I2C_MINORS      MINORMASK
  56 static LIST_HEAD(i2c_dev_list);
  57 static DEFINE_SPINLOCK(i2c_dev_list_lock);
  58
  59 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
  60 {
  61         struct i2c_dev *i2c_dev;
  62
  63         spin_lock(&i2c_dev_list_lock);
  64         list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
  65                 if (i2c_dev->adap->nr == index)
  66                         goto found;
  67         }
  68         i2c_dev = NULL;
  69 found:
  70         spin_unlock(&i2c_dev_list_lock);
  71         return i2c_dev;
  72 }
  73
  74 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
  75 {
  76         struct i2c_dev *i2c_dev;
  77
  78         if (adap->nr >= I2C_MINORS) {
  79                 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
  80                        adap->nr);
  81                 return ERR_PTR(-ENODEV);
  82         }
  83
  84         i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
  85         if (!i2c_dev)
  86                 return ERR_PTR(-ENOMEM);
  87         i2c_dev->adap = adap;
  88
  89         spin_lock(&i2c_dev_list_lock);
  90         list_add_tail(&i2c_dev->list, &i2c_dev_list);
  91         spin_unlock(&i2c_dev_list_lock);
  92         return i2c_dev;
  93 }
  94
  95 static void put_i2c_dev(struct i2c_dev *i2c_dev)
  96 {
  97         spin_lock(&i2c_dev_list_lock);
  98         list_del(&i2c_dev->list);
  99         spin_unlock(&i2c_dev_list_lock);
 100         kfree(i2c_dev);
 101 }
 102
 103 static ssize_t name_show(struct device *dev,
 104                          struct device_attribute *attr, char *buf)
 105 {
 106         struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
 107
 108         if (!i2c_dev)
 109                 return -ENODEV;
 110         return sprintf(buf, "%s\n", i2c_dev->adap->name);
 111 }
 112 static DEVICE_ATTR_RO(name);
 113
 114 static struct attribute *i2c_attrs[] = {
 115         &dev_attr_name.attr,
 116         NULL,
 117 };
 118 ATTRIBUTE_GROUPS(i2c);
 119
 120 /* ------------------------------------------------------------------------- */
 121
 122 /*
 123  * After opening an instance of this character special file, a file
 124  * descriptor starts out associated only with an i2c_adapter (and bus).
 125  *
 126  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
 127  * traffic to any devices on the bus used by that adapter.  That's because
 128  * the i2c_msg vectors embed all the addressing information they need, and
 129  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
 130  * don't support that interface.
 131  *
 132  * To use read()/write() system calls on that file descriptor, or to use
 133  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
 134  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
 135  * (never registered) i2c_client so it holds the addressing information
 136  * needed by those system calls and by this SMBus interface.
 137  */
 138
 139 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
 140                 loff_t *offset)
 141 {
 142         char *tmp;
 143         int ret;
 144
 145         struct i2c_client *client = file->private_data;
 146
 147         if (count > 8192)
 148                 count = 8192;
 149
 150         tmp = kmalloc(count, GFP_KERNEL);
 151         if (tmp == NULL)
 152                 return -ENOMEM;
 153
 154         pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
 155                 iminor(file_inode(file)), count);
 156
 157         ret = i2c_master_recv(client, tmp, count);
 158         if (ret >= 0)
 159                 ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
 160         kfree(tmp);
 161         return ret;
 162 }
 163
 164 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
 165                 size_t count, loff_t *offset)
 166 {
 167         int ret;
 168         char *tmp;
 169         struct i2c_client *client = file->private_data;
 170
 171         if (count > 8192)
 172                 count = 8192;
 173
 174         tmp = memdup_user(buf, count);
 175         if (IS_ERR(tmp))
 176                 return PTR_ERR(tmp);
 177
 178         pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 179                 iminor(file_inode(file)), count);
 180
 181         ret = i2c_master_send(client, tmp, count);
 182         kfree(tmp);
 183         return ret;
 184 }
 185
 186 static int i2cdev_check(struct device *dev, void *addrp)
 187 {
 188         struct i2c_client *client = i2c_verify_client(dev);
 189
 190         if (!client || client->addr != *(unsigned int *)addrp)
 191                 return 0;
 192
 193         return dev->driver ? -EBUSY : 0;
 194 }
 195
 196 /* walk up mux tree */
 197 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 198 {
 199         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 200         int result;
 201
 202         result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 203         if (!result && parent)
 204                 result = i2cdev_check_mux_parents(parent, addr);
 205
 206         return result;
 207 }
 208
 209 /* recurse down mux tree */
 210 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 211 {
 212         int result;
 213
 214         if (dev->type == &i2c_adapter_type)
 215                 result = device_for_each_child(dev, addrp,
 216                                                 i2cdev_check_mux_children);
 217         else
 218                 result = i2cdev_check(dev, addrp);
 219
 220         return result;
 221 }
 222
 223 /* This address checking function differs from the one in i2c-core
 224    in that it considers an address with a registered device, but no
 225    driver bound to it, as NOT busy. */
 226 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 227 {
 228         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 229         int result = 0;
 230
 231         if (parent)
 232                 result = i2cdev_check_mux_parents(parent, addr);
 233
 234         if (!result)
 235                 result = device_for_each_child(&adapter->dev, &addr,
 236                                                 i2cdev_check_mux_children);
 237
 238         return result;
 239 }
 240
 241 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
 242                 unsigned nmsgs, struct i2c_msg *msgs)
 243 {
 244         u8 __user **data_ptrs;
 245         int i, res;
 246
 247         data_ptrs = kmalloc(nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 248         if (data_ptrs == NULL) {
 249                 kfree(msgs);
 250                 return -ENOMEM;
 251         }
 252
 253         res = 0;
 254         for (i = 0; i < nmsgs; i++) {
 255                 /* Limit the size of the message to a sane amount */
 256                 if (msgs[i].len > 8192) {
 257                         res = -EINVAL;
 258                         break;
 259                 }
 260
 261                 data_ptrs[i] = (u8 __user *)msgs[i].buf;
 262                 msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
 263                 if (IS_ERR(msgs[i].buf)) {
 264                         res = PTR_ERR(msgs[i].buf);
 265                         break;
 266                 }
 267                 /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
 268                 msgs[i].flags |= I2C_M_DMA_SAFE;
 269
 270                 /*
 271                  * If the message length is received from the slave (similar
 272                  * to SMBus block read), we must ensure that the buffer will
 273                  * be large enough to cope with a message length of
 274                  * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
 275                  * drivers allow. The first byte in the buffer must be
 276                  * pre-filled with the number of extra bytes, which must be
 277                  * at least one to hold the message length, but can be
 278                  * greater (for example to account for a checksum byte at
 279                  * the end of the message.)
 280                  */
 281                 if (msgs[i].flags & I2C_M_RECV_LEN) {
 282                         if (!(msgs[i].flags & I2C_M_RD) ||
 283                             msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
 284                             msgs[i].len < msgs[i].buf[0] +
 285                                              I2C_SMBUS_BLOCK_MAX) {
 286                                 res = -EINVAL;
 287                                 break;
 288                         }
 289
 290                         msgs[i].len = msgs[i].buf[0];
 291                 }
 292         }
 293         if (res < 0) {
 294                 int j;
 295                 for (j = 0; j < i; ++j)
 296                         kfree(msgs[j].buf);
 297                 kfree(data_ptrs);
 298                 kfree(msgs);
 299                 return res;
 300         }
 301
 302         res = i2c_transfer(client->adapter, msgs, nmsgs);
 303         while (i-- > 0) {
 304                 if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
 305                         if (copy_to_user(data_ptrs[i], msgs[i].buf,
 306                                          msgs[i].len))
 307                                 res = -EFAULT;
 308                 }
 309                 kfree(msgs[i].buf);
 310         }
 311         kfree(data_ptrs);
 312         kfree(msgs);
 313         return res;
 314 }
 315
 316 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 317                 u8 read_write, u8 command, u32 size,
 318                 union i2c_smbus_data __user *data)
 319 {
 320         union i2c_smbus_data temp = {};
 321         int datasize, res;
 322
 323         if ((size != I2C_SMBUS_BYTE) &&
 324             (size != I2C_SMBUS_QUICK) &&
 325             (size != I2C_SMBUS_BYTE_DATA) &&
 326             (size != I2C_SMBUS_WORD_DATA) &&
 327             (size != I2C_SMBUS_PROC_CALL) &&
 328             (size != I2C_SMBUS_BLOCK_DATA) &&
 329             (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 330             (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 331             (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 332                 dev_dbg(&client->adapter->dev,
 333                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 334                         size);
 335                 return -EINVAL;
 336         }
 337         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 338            so the check is valid if size==I2C_SMBUS_QUICK too. */
 339         if ((read_write != I2C_SMBUS_READ) &&
 340             (read_write != I2C_SMBUS_WRITE)) {
 341                 dev_dbg(&client->adapter->dev,
 342                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 343                         read_write);
 344                 return -EINVAL;
 345         }
 346
 347         /* Note that command values are always valid! */
 348
 349         if ((size == I2C_SMBUS_QUICK) ||
 350             ((size == I2C_SMBUS_BYTE) &&
 351             (read_write == I2C_SMBUS_WRITE)))
 352                 /* These are special: we do not use data */
 353                 return i2c_smbus_xfer(client->adapter, client->addr,
 354                                       client->flags, read_write,
 355                                       command, size, NULL);
 356
 357         if (data == NULL) {
 358                 dev_dbg(&client->adapter->dev,
 359                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 360                 return -EINVAL;
 361         }
 362
 363         if ((size == I2C_SMBUS_BYTE_DATA) ||
 364             (size == I2C_SMBUS_BYTE))
 365                 datasize = sizeof(data->byte);
 366         else if ((size == I2C_SMBUS_WORD_DATA) ||
 367                  (size == I2C_SMBUS_PROC_CALL))
 368                 datasize = sizeof(data->word);
 369         else /* size == smbus block, i2c block, or block proc. call */
 370                 datasize = sizeof(data->block);
 371
 372         if ((size == I2C_SMBUS_PROC_CALL) ||
 373             (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 374             (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 375             (read_write == I2C_SMBUS_WRITE)) {
 376                 if (copy_from_user(&temp, data, datasize))
 377                         return -EFAULT;
 378         }
 379         if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 380                 /* Convert old I2C block commands to the new
 381                    convention. This preserves binary compatibility. */
 382                 size = I2C_SMBUS_I2C_BLOCK_DATA;
 383                 if (read_write == I2C_SMBUS_READ)
 384                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 385         }
 386         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 387               read_write, command, size, &temp);
 388         if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
 389                      (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 390                      (read_write == I2C_SMBUS_READ))) {
 391                 if (copy_to_user(data, &temp, datasize))
 392                         return -EFAULT;
 393         }
 394         return res;
 395 }
 396
 397 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 398 {
 399         struct i2c_client *client = file->private_data;
 400         unsigned long funcs;
 401
 402         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 403                 cmd, arg);
 404
 405         switch (cmd) {
 406         case I2C_SLAVE:
 407         case I2C_SLAVE_FORCE:
 408                 if ((arg > 0x3ff) ||
 409                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 410                         return -EINVAL;
 411                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 412                         return -EBUSY;
 413                 /* REVISIT: address could become busy later */
 414                 client->addr = arg;
 415                 return 0;
 416         case I2C_TENBIT:
 417                 if (arg)
 418                         client->flags |= I2C_M_TEN;
 419                 else
 420                         client->flags &= ~I2C_M_TEN;
 421                 return 0;
 422         case I2C_PEC:
 423                 /*
 424                  * Setting the PEC flag here won't affect kernel drivers,
 425                  * which will be using the i2c_client node registered with
 426                  * the driver model core.  Likewise, when that client has
 427                  * the PEC flag already set, the i2c-dev driver won't see
 428                  * (or use) this setting.
 429                  */
 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                 struct i2c_rdwr_ioctl_data rdwr_arg;
 441                 struct i2c_msg *rdwr_pa;
 442
 443                 if (copy_from_user(&rdwr_arg,
 444                                    (struct i2c_rdwr_ioctl_data __user *)arg,
 445                                    sizeof(rdwr_arg)))
 446                         return -EFAULT;
 447
 448                 /* Put an arbitrary limit on the number of messages that can
 449                  * be sent at once */
 450                 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 451                         return -EINVAL;
 452
 453                 rdwr_pa = memdup_user(rdwr_arg.msgs,
 454                                       rdwr_arg.nmsgs * sizeof(struct i2c_msg));
 455                 if (IS_ERR(rdwr_pa))
 456                         return PTR_ERR(rdwr_pa);
 457
 458                 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
 459         }
 460
 461         case I2C_SMBUS: {
 462                 struct i2c_smbus_ioctl_data data_arg;
 463                 if (copy_from_user(&data_arg,
 464                                    (struct i2c_smbus_ioctl_data __user *) arg,
 465                                    sizeof(struct i2c_smbus_ioctl_data)))
 466                         return -EFAULT;
 467                 return i2cdev_ioctl_smbus(client, data_arg.read_write,
 468                                           data_arg.command,
 469                                           data_arg.size,
 470                                           data_arg.data);
 471         }
 472         case I2C_RETRIES:
 473                 client->adapter->retries = arg;
 474                 break;
 475         case I2C_TIMEOUT:
 476                 /* For historical reasons, user-space sets the timeout
 477                  * value in units of 10 ms.
 478                  */
 479                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 480                 break;
 481         default:
 482                 /* NOTE:  returning a fault code here could cause trouble
 483                  * in buggy userspace code.  Some old kernel bugs returned
 484                  * zero in this case, and userspace code might accidentally
 485                  * have depended on that bug.
 486                  */
 487                 return -ENOTTY;
 488         }
 489         return 0;
 490 }
 491
 492 #ifdef CONFIG_COMPAT
 493
 494 struct i2c_smbus_ioctl_data32 {
 495         u8 read_write;
 496         u8 command;
 497         u32 size;
 498         compat_caddr_t data; /* union i2c_smbus_data *data */
 499 };
 500
 501 struct i2c_msg32 {
 502         u16 addr;
 503         u16 flags;
 504         u16 len;
 505         compat_caddr_t buf;
 506 };
 507
 508 struct i2c_rdwr_ioctl_data32 {
 509         compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
 510         u32 nmsgs;
 511 };
 512
 513 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 514 {
 515         struct i2c_client *client = file->private_data;
 516         unsigned long funcs;
 517         switch (cmd) {
 518         case I2C_FUNCS:
 519                 funcs = i2c_get_functionality(client->adapter);
 520                 return put_user(funcs, (compat_ulong_t __user *)arg);
 521         case I2C_RDWR: {
 522                 struct i2c_rdwr_ioctl_data32 rdwr_arg;
 523                 struct i2c_msg32 *p;
 524                 struct i2c_msg *rdwr_pa;
 525                 int i;
 526
 527                 if (copy_from_user(&rdwr_arg,
 528                                    (struct i2c_rdwr_ioctl_data32 __user *)arg,
 529                                    sizeof(rdwr_arg)))
 530                         return -EFAULT;
 531
 532                 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 533                         return -EINVAL;
 534
 535                 rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
 536                                       GFP_KERNEL);
 537                 if (!rdwr_pa)
 538                         return -ENOMEM;
 539
 540                 p = compat_ptr(rdwr_arg.msgs);
 541                 for (i = 0; i < rdwr_arg.nmsgs; i++) {
 542                         struct i2c_msg32 umsg;
 543                         if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
 544                                 kfree(rdwr_pa);
 545                                 return -EFAULT;
 546                         }
 547                         rdwr_pa[i] = (struct i2c_msg) {
 548                                 .addr = umsg.addr,
 549                                 .flags = umsg.flags,
 550                                 .len = umsg.len,
 551                                 .buf = compat_ptr(umsg.buf)
 552                         };
 553                 }
 554
 555                 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
 556         }
 557         case I2C_SMBUS: {
 558                 struct i2c_smbus_ioctl_data32   data32;
 559                 if (copy_from_user(&data32,
 560                                    (void __user *) arg,
 561                                    sizeof(data32)))
 562                         return -EFAULT;
 563                 return i2cdev_ioctl_smbus(client, data32.read_write,
 564                                           data32.command,
 565                                           data32.size,
 566                                           compat_ptr(data32.data));
 567         }
 568         default:
 569                 return i2cdev_ioctl(file, cmd, arg);
 570         }
 571 }
 572 #else
 573 #define compat_i2cdev_ioctl NULL
 574 #endif
 575
 576 static int i2cdev_open(struct inode *inode, struct file *file)
 577 {
 578         unsigned int minor = iminor(inode);
 579         struct i2c_client *client;
 580         struct i2c_adapter *adap;
 581
 582         adap = i2c_get_adapter(minor);
 583         if (!adap)
 584                 return -ENODEV;
 585
 586         /* This creates an anonymous i2c_client, which may later be
 587          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 588          *
 589          * This client is ** NEVER REGISTERED ** with the driver model
 590          * or I2C core code!!  It just holds private copies of addressing
 591          * information and maybe a PEC flag.
 592          */
 593         client = kzalloc(sizeof(*client), GFP_KERNEL);
 594         if (!client) {
 595                 i2c_put_adapter(adap);
 596                 return -ENOMEM;
 597         }
 598         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 599
 600         client->adapter = adap;
 601         file->private_data = client;
 602
 603         return 0;
 604 }
 605
 606 static int i2cdev_release(struct inode *inode, struct file *file)
 607 {
 608         struct i2c_client *client = file->private_data;
 609
 610         i2c_put_adapter(client->adapter);
 611         kfree(client);
 612         file->private_data = NULL;
 613
 614         return 0;
 615 }
 616
 617 static const struct file_operations i2cdev_fops = {
 618         .owner          = THIS_MODULE,
 619         .llseek         = no_llseek,
 620         .read           = i2cdev_read,
 621         .write          = i2cdev_write,
 622         .unlocked_ioctl = i2cdev_ioctl,
 623         .compat_ioctl   = compat_i2cdev_ioctl,
 624         .open           = i2cdev_open,
 625         .release        = i2cdev_release,
 626 };
 627
 628 /* ------------------------------------------------------------------------- */
 629
 630 static struct class *i2c_dev_class;
 631
 632 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 633 {
 634         struct i2c_adapter *adap;
 635         struct i2c_dev *i2c_dev;
 636         int res;
 637
 638         if (dev->type != &i2c_adapter_type)
 639                 return 0;
 640         adap = to_i2c_adapter(dev);
 641
 642         i2c_dev = get_free_i2c_dev(adap);
 643         if (IS_ERR(i2c_dev))
 644                 return PTR_ERR(i2c_dev);
 645
 646         cdev_init(&i2c_dev->cdev, &i2cdev_fops);
 647         i2c_dev->cdev.owner = THIS_MODULE;
 648         res = cdev_add(&i2c_dev->cdev, MKDEV(I2C_MAJOR, adap->nr), 1);
 649         if (res)
 650                 goto error_cdev;
 651
 652         /* register this i2c device with the driver core */
 653         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 654                                      MKDEV(I2C_MAJOR, adap->nr), NULL,
 655                                      "i2c-%d", adap->nr);
 656         if (IS_ERR(i2c_dev->dev)) {
 657                 res = PTR_ERR(i2c_dev->dev);
 658                 goto error;
 659         }
 660
 661         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 662                  adap->name, adap->nr);
 663         return 0;
 664 error:
 665         cdev_del(&i2c_dev->cdev);
 666 error_cdev:
 667         put_i2c_dev(i2c_dev);
 668         return res;
 669 }
 670
 671 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 672 {
 673         struct i2c_adapter *adap;
 674         struct i2c_dev *i2c_dev;
 675
 676         if (dev->type != &i2c_adapter_type)
 677                 return 0;
 678         adap = to_i2c_adapter(dev);
 679
 680         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 681         if (!i2c_dev) /* attach_adapter must have failed */
 682                 return 0;
 683
 684         cdev_del(&i2c_dev->cdev);
 685         put_i2c_dev(i2c_dev);
 686         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 687
 688         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 689         return 0;
 690 }
 691
 692 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 693                          void *data)
 694 {
 695         struct device *dev = data;
 696
 697         switch (action) {
 698         case BUS_NOTIFY_ADD_DEVICE:
 699                 return i2cdev_attach_adapter(dev, NULL);
 700         case BUS_NOTIFY_DEL_DEVICE:
 701                 return i2cdev_detach_adapter(dev, NULL);
 702         }
 703
 704         return 0;
 705 }
 706
 707 static struct notifier_block i2cdev_notifier = {
 708         .notifier_call = i2cdev_notifier_call,
 709 };
 710
 711 /* ------------------------------------------------------------------------- */
 712
 713 /*
 714  * module load/unload record keeping
 715  */
 716
 717 static int __init i2c_dev_init(void)
 718 {
 719         int res;
 720
 721         printk(KERN_INFO "i2c /dev entries driver\n");
 722
 723         res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
 724         if (res)
 725                 goto out;
 726
 727         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 728         if (IS_ERR(i2c_dev_class)) {
 729                 res = PTR_ERR(i2c_dev_class);
 730                 goto out_unreg_chrdev;
 731         }
 732         i2c_dev_class->dev_groups = i2c_groups;
 733
 734         /* Keep track of adapters which will be added or removed later */
 735         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 736         if (res)
 737                 goto out_unreg_class;
 738
 739         /* Bind to already existing adapters right away */
 740         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 741
 742         return 0;
 743
 744 out_unreg_class:
 745         class_destroy(i2c_dev_class);
 746 out_unreg_chrdev:
 747         unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 748 out:
 749         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 750         return res;
 751 }
 752
 753 static void __exit i2c_dev_exit(void)
 754 {
 755         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 756         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 757         class_destroy(i2c_dev_class);
 758         unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 759 }
 760
 761 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 762                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 763 MODULE_DESCRIPTION("I2C /dev entries driver");
 764 MODULE_LICENSE("GPL");
 765
 766 module_init(i2c_dev_init);
 767 module_exit(i2c_dev_exit);