drivers/i2c/i2c-dev.c

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This source file includes following definitions.
i2c_dev_get_by_minor
get_free_i2c_dev
put_i2c_dev
name_show
i2cdev_read
i2cdev_write
i2cdev_check
i2cdev_check_mux_parents
i2cdev_check_mux_children
i2cdev_check_addr
i2cdev_ioctl_rdwr
i2cdev_ioctl_smbus
i2cdev_ioctl
compat_i2cdev_ioctl
i2cdev_open
i2cdev_release
i2cdev_dev_release
i2cdev_attach_adapter
i2cdev_detach_adapter
i2cdev_notifier_call
i2c_dev_init
i2c_dev_exit
   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3     i2c-dev.c - i2c-bus driver, char device interface
   4 
   5     Copyright (C) 1995-97 Simon G. Vogl
   6     Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
   7     Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   8 
   9 */
  10 
  11 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
  12    But I have used so much of his original code and ideas that it seems
  13    only fair to recognize him as co-author -- Frodo */
  14 
  15 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
  16 
  17 #include <linux/cdev.h>
  18 #include <linux/device.h>
  19 #include <linux/fs.h>
  20 #include <linux/i2c-dev.h>
  21 #include <linux/i2c.h>
  22 #include <linux/init.h>
  23 #include <linux/jiffies.h>
  24 #include <linux/kernel.h>
  25 #include <linux/list.h>
  26 #include <linux/module.h>
  27 #include <linux/notifier.h>
  28 #include <linux/slab.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/compat.h>
  31 
  32 /*
  33  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  34  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  35  * with a character special file which is accessed by user mode drivers.
  36  *
  37  * The list of i2c_dev structures is parallel to the i2c_adapter lists
  38  * maintained by the driver model, and is updated using bus notifications.
  39  */
  40 struct i2c_dev {
  41         struct list_head list;
  42         struct i2c_adapter *adap;
  43         struct device dev;
  44         struct cdev cdev;
  45 };
  46 
  47 #define I2C_MINORS      (MINORMASK + 1)
  48 static LIST_HEAD(i2c_dev_list);
  49 static DEFINE_SPINLOCK(i2c_dev_list_lock);
  50 
  51 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
  52 {
  53         struct i2c_dev *i2c_dev;
  54 
  55         spin_lock(&i2c_dev_list_lock);
  56         list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
  57                 if (i2c_dev->adap->nr == index)
  58                         goto found;
  59         }
  60         i2c_dev = NULL;
  61 found:
  62         spin_unlock(&i2c_dev_list_lock);
  63         return i2c_dev;
  64 }
  65 
  66 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
  67 {
  68         struct i2c_dev *i2c_dev;
  69 
  70         if (adap->nr >= I2C_MINORS) {
  71                 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
  72                        adap->nr);
  73                 return ERR_PTR(-ENODEV);
  74         }
  75 
  76         i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
  77         if (!i2c_dev)
  78                 return ERR_PTR(-ENOMEM);
  79         i2c_dev->adap = adap;
  80 
  81         spin_lock(&i2c_dev_list_lock);
  82         list_add_tail(&i2c_dev->list, &i2c_dev_list);
  83         spin_unlock(&i2c_dev_list_lock);
  84         return i2c_dev;
  85 }
  86 
  87 static void put_i2c_dev(struct i2c_dev *i2c_dev, bool del_cdev)
  88 {
  89         spin_lock(&i2c_dev_list_lock);
  90         list_del(&i2c_dev->list);
  91         spin_unlock(&i2c_dev_list_lock);
  92         if (del_cdev)
  93                 cdev_device_del(&i2c_dev->cdev, &i2c_dev->dev);
  94         put_device(&i2c_dev->dev);
  95 }
  96 
  97 static ssize_t name_show(struct device *dev,
  98                          struct device_attribute *attr, char *buf)
  99 {
 100         struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
 101 
 102         if (!i2c_dev)
 103                 return -ENODEV;
 104         return sprintf(buf, "%s\n", i2c_dev->adap->name);
 105 }
 106 static DEVICE_ATTR_RO(name);
 107 
 108 static struct attribute *i2c_attrs[] = {
 109         &dev_attr_name.attr,
 110         NULL,
 111 };
 112 ATTRIBUTE_GROUPS(i2c);
 113 
 114 /* ------------------------------------------------------------------------- */
 115 
 116 /*
 117  * After opening an instance of this character special file, a file
 118  * descriptor starts out associated only with an i2c_adapter (and bus).
 119  *
 120  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
 121  * traffic to any devices on the bus used by that adapter.  That's because
 122  * the i2c_msg vectors embed all the addressing information they need, and
 123  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
 124  * don't support that interface.
 125  *
 126  * To use read()/write() system calls on that file descriptor, or to use
 127  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
 128  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
 129  * (never registered) i2c_client so it holds the addressing information
 130  * needed by those system calls and by this SMBus interface.
 131  */
 132 
 133 static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
 134                 loff_t *offset)
 135 {
 136         char *tmp;
 137         int ret;
 138 
 139         struct i2c_client *client = file->private_data;
 140 
 141         if (count > 8192)
 142                 count = 8192;
 143 
 144         tmp = kmalloc(count, GFP_KERNEL);
 145         if (tmp == NULL)
 146                 return -ENOMEM;
 147 
 148         pr_debug("i2c-dev: i2c-%d reading %zu bytes.\n",
 149                 iminor(file_inode(file)), count);
 150 
 151         ret = i2c_master_recv(client, tmp, count);
 152         if (ret >= 0)
 153                 ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
 154         kfree(tmp);
 155         return ret;
 156 }
 157 
 158 static ssize_t i2cdev_write(struct file *file, const char __user *buf,
 159                 size_t count, loff_t *offset)
 160 {
 161         int ret;
 162         char *tmp;
 163         struct i2c_client *client = file->private_data;
 164 
 165         if (count > 8192)
 166                 count = 8192;
 167 
 168         tmp = memdup_user(buf, count);
 169         if (IS_ERR(tmp))
 170                 return PTR_ERR(tmp);
 171 
 172         pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 173                 iminor(file_inode(file)), count);
 174 
 175         ret = i2c_master_send(client, tmp, count);
 176         kfree(tmp);
 177         return ret;
 178 }
 179 
 180 static int i2cdev_check(struct device *dev, void *addrp)
 181 {
 182         struct i2c_client *client = i2c_verify_client(dev);
 183 
 184         if (!client || client->addr != *(unsigned int *)addrp)
 185                 return 0;
 186 
 187         return dev->driver ? -EBUSY : 0;
 188 }
 189 
 190 /* walk up mux tree */
 191 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 192 {
 193         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 194         int result;
 195 
 196         result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 197         if (!result && parent)
 198                 result = i2cdev_check_mux_parents(parent, addr);
 199 
 200         return result;
 201 }
 202 
 203 /* recurse down mux tree */
 204 static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 205 {
 206         int result;
 207 
 208         if (dev->type == &i2c_adapter_type)
 209                 result = device_for_each_child(dev, addrp,
 210                                                 i2cdev_check_mux_children);
 211         else
 212                 result = i2cdev_check(dev, addrp);
 213 
 214         return result;
 215 }
 216 
 217 /* This address checking function differs from the one in i2c-core
 218    in that it considers an address with a registered device, but no
 219    driver bound to it, as NOT busy. */
 220 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 221 {
 222         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 223         int result = 0;
 224 
 225         if (parent)
 226                 result = i2cdev_check_mux_parents(parent, addr);
 227 
 228         if (!result)
 229                 result = device_for_each_child(&adapter->dev, &addr,
 230                                                 i2cdev_check_mux_children);
 231 
 232         return result;
 233 }
 234 
 235 static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
 236                 unsigned nmsgs, struct i2c_msg *msgs)
 237 {
 238         u8 __user **data_ptrs;
 239         int i, res;
 240 
 241         data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
 242         if (data_ptrs == NULL) {
 243                 kfree(msgs);
 244                 return -ENOMEM;
 245         }
 246 
 247         res = 0;
 248         for (i = 0; i < nmsgs; i++) {
 249                 /* Limit the size of the message to a sane amount */
 250                 if (msgs[i].len > 8192) {
 251                         res = -EINVAL;
 252                         break;
 253                 }
 254 
 255                 data_ptrs[i] = (u8 __user *)msgs[i].buf;
 256                 msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
 257                 if (IS_ERR(msgs[i].buf)) {
 258                         res = PTR_ERR(msgs[i].buf);
 259                         break;
 260                 }
 261                 /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
 262                 msgs[i].flags |= I2C_M_DMA_SAFE;
 263 
 264                 /*
 265                  * If the message length is received from the slave (similar
 266                  * to SMBus block read), we must ensure that the buffer will
 267                  * be large enough to cope with a message length of
 268                  * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
 269                  * drivers allow. The first byte in the buffer must be
 270                  * pre-filled with the number of extra bytes, which must be
 271                  * at least one to hold the message length, but can be
 272                  * greater (for example to account for a checksum byte at
 273                  * the end of the message.)
 274                  */
 275                 if (msgs[i].flags & I2C_M_RECV_LEN) {
 276                         if (!(msgs[i].flags & I2C_M_RD) ||
 277                             msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
 278                             msgs[i].len < msgs[i].buf[0] +
 279                                              I2C_SMBUS_BLOCK_MAX) {
 280                                 i++;
 281                                 res = -EINVAL;
 282                                 break;
 283                         }
 284 
 285                         msgs[i].len = msgs[i].buf[0];
 286                 }
 287         }
 288         if (res < 0) {
 289                 int j;
 290                 for (j = 0; j < i; ++j)
 291                         kfree(msgs[j].buf);
 292                 kfree(data_ptrs);
 293                 kfree(msgs);
 294                 return res;
 295         }
 296 
 297         res = i2c_transfer(client->adapter, msgs, nmsgs);
 298         while (i-- > 0) {
 299                 if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
 300                         if (copy_to_user(data_ptrs[i], msgs[i].buf,
 301                                          msgs[i].len))
 302                                 res = -EFAULT;
 303                 }
 304                 kfree(msgs[i].buf);
 305         }
 306         kfree(data_ptrs);
 307         kfree(msgs);
 308         return res;
 309 }
 310 
 311 static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 312                 u8 read_write, u8 command, u32 size,
 313                 union i2c_smbus_data __user *data)
 314 {
 315         union i2c_smbus_data temp = {};
 316         int datasize, res;
 317 
 318         if ((size != I2C_SMBUS_BYTE) &&
 319             (size != I2C_SMBUS_QUICK) &&
 320             (size != I2C_SMBUS_BYTE_DATA) &&
 321             (size != I2C_SMBUS_WORD_DATA) &&
 322             (size != I2C_SMBUS_PROC_CALL) &&
 323             (size != I2C_SMBUS_BLOCK_DATA) &&
 324             (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 325             (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 326             (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 327                 dev_dbg(&client->adapter->dev,
 328                         "size out of range (%x) in ioctl I2C_SMBUS.\n",
 329                         size);
 330                 return -EINVAL;
 331         }
 332         /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 333            so the check is valid if size==I2C_SMBUS_QUICK too. */
 334         if ((read_write != I2C_SMBUS_READ) &&
 335             (read_write != I2C_SMBUS_WRITE)) {
 336                 dev_dbg(&client->adapter->dev,
 337                         "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 338                         read_write);
 339                 return -EINVAL;
 340         }
 341 
 342         /* Note that command values are always valid! */
 343 
 344         if ((size == I2C_SMBUS_QUICK) ||
 345             ((size == I2C_SMBUS_BYTE) &&
 346             (read_write == I2C_SMBUS_WRITE)))
 347                 /* These are special: we do not use data */
 348                 return i2c_smbus_xfer(client->adapter, client->addr,
 349                                       client->flags, read_write,
 350                                       command, size, NULL);
 351 
 352         if (data == NULL) {
 353                 dev_dbg(&client->adapter->dev,
 354                         "data is NULL pointer in ioctl I2C_SMBUS.\n");
 355                 return -EINVAL;
 356         }
 357 
 358         if ((size == I2C_SMBUS_BYTE_DATA) ||
 359             (size == I2C_SMBUS_BYTE))
 360                 datasize = sizeof(data->byte);
 361         else if ((size == I2C_SMBUS_WORD_DATA) ||
 362                  (size == I2C_SMBUS_PROC_CALL))
 363                 datasize = sizeof(data->word);
 364         else /* size == smbus block, i2c block, or block proc. call */
 365                 datasize = sizeof(data->block);
 366 
 367         if ((size == I2C_SMBUS_PROC_CALL) ||
 368             (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 369             (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 370             (read_write == I2C_SMBUS_WRITE)) {
 371                 if (copy_from_user(&temp, data, datasize))
 372                         return -EFAULT;
 373         }
 374         if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 375                 /* Convert old I2C block commands to the new
 376                    convention. This preserves binary compatibility. */
 377                 size = I2C_SMBUS_I2C_BLOCK_DATA;
 378                 if (read_write == I2C_SMBUS_READ)
 379                         temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 380         }
 381         res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 382               read_write, command, size, &temp);
 383         if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
 384                      (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 385                      (read_write == I2C_SMBUS_READ))) {
 386                 if (copy_to_user(data, &temp, datasize))
 387                         return -EFAULT;
 388         }
 389         return res;
 390 }
 391 
 392 static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 393 {
 394         struct i2c_client *client = file->private_data;
 395         unsigned long funcs;
 396 
 397         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 398                 cmd, arg);
 399 
 400         switch (cmd) {
 401         case I2C_SLAVE:
 402         case I2C_SLAVE_FORCE:
 403                 if ((arg > 0x3ff) ||
 404                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 405                         return -EINVAL;
 406                 if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 407                         return -EBUSY;
 408                 /* REVISIT: address could become busy later */
 409                 client->addr = arg;
 410                 return 0;
 411         case I2C_TENBIT:
 412                 if (arg)
 413                         client->flags |= I2C_M_TEN;
 414                 else
 415                         client->flags &= ~I2C_M_TEN;
 416                 return 0;
 417         case I2C_PEC:
 418                 /*
 419                  * Setting the PEC flag here won't affect kernel drivers,
 420                  * which will be using the i2c_client node registered with
 421                  * the driver model core.  Likewise, when that client has
 422                  * the PEC flag already set, the i2c-dev driver won't see
 423                  * (or use) this setting.
 424                  */
 425                 if (arg)
 426                         client->flags |= I2C_CLIENT_PEC;
 427                 else
 428                         client->flags &= ~I2C_CLIENT_PEC;
 429                 return 0;
 430         case I2C_FUNCS:
 431                 funcs = i2c_get_functionality(client->adapter);
 432                 return put_user(funcs, (unsigned long __user *)arg);
 433 
 434         case I2C_RDWR: {
 435                 struct i2c_rdwr_ioctl_data rdwr_arg;
 436                 struct i2c_msg *rdwr_pa;
 437 
 438                 if (copy_from_user(&rdwr_arg,
 439                                    (struct i2c_rdwr_ioctl_data __user *)arg,
 440                                    sizeof(rdwr_arg)))
 441                         return -EFAULT;
 442 
 443                 /* Put an arbitrary limit on the number of messages that can
 444                  * be sent at once */
 445                 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 446                         return -EINVAL;
 447 
 448                 rdwr_pa = memdup_user(rdwr_arg.msgs,
 449                                       rdwr_arg.nmsgs * sizeof(struct i2c_msg));
 450                 if (IS_ERR(rdwr_pa))
 451                         return PTR_ERR(rdwr_pa);
 452 
 453                 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
 454         }
 455 
 456         case I2C_SMBUS: {
 457                 struct i2c_smbus_ioctl_data data_arg;
 458                 if (copy_from_user(&data_arg,
 459                                    (struct i2c_smbus_ioctl_data __user *) arg,
 460                                    sizeof(struct i2c_smbus_ioctl_data)))
 461                         return -EFAULT;
 462                 return i2cdev_ioctl_smbus(client, data_arg.read_write,
 463                                           data_arg.command,
 464                                           data_arg.size,
 465                                           data_arg.data);
 466         }
 467         case I2C_RETRIES:
 468                 if (arg > INT_MAX)
 469                         return -EINVAL;
 470 
 471                 client->adapter->retries = arg;
 472                 break;
 473         case I2C_TIMEOUT:
 474                 if (arg > INT_MAX)
 475                         return -EINVAL;
 476 
 477                 /* For historical reasons, user-space sets the timeout
 478                  * value in units of 10 ms.
 479                  */
 480                 client->adapter->timeout = msecs_to_jiffies(arg * 10);
 481                 break;
 482         default:
 483                 /* NOTE:  returning a fault code here could cause trouble
 484                  * in buggy userspace code.  Some old kernel bugs returned
 485                  * zero in this case, and userspace code might accidentally
 486                  * have depended on that bug.
 487                  */
 488                 return -ENOTTY;
 489         }
 490         return 0;
 491 }
 492 
 493 #ifdef CONFIG_COMPAT
 494 
 495 struct i2c_smbus_ioctl_data32 {
 496         u8 read_write;
 497         u8 command;
 498         u32 size;
 499         compat_caddr_t data; /* union i2c_smbus_data *data */
 500 };
 501 
 502 struct i2c_msg32 {
 503         u16 addr;
 504         u16 flags;
 505         u16 len;
 506         compat_caddr_t buf;
 507 };
 508 
 509 struct i2c_rdwr_ioctl_data32 {
 510         compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
 511         u32 nmsgs;
 512 };
 513 
 514 static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 515 {
 516         struct i2c_client *client = file->private_data;
 517         unsigned long funcs;
 518         switch (cmd) {
 519         case I2C_FUNCS:
 520                 funcs = i2c_get_functionality(client->adapter);
 521                 return put_user(funcs, (compat_ulong_t __user *)arg);
 522         case I2C_RDWR: {
 523                 struct i2c_rdwr_ioctl_data32 rdwr_arg;
 524                 struct i2c_msg32 *p;
 525                 struct i2c_msg *rdwr_pa;
 526                 int i;
 527 
 528                 if (copy_from_user(&rdwr_arg,
 529                                    (struct i2c_rdwr_ioctl_data32 __user *)arg,
 530                                    sizeof(rdwr_arg)))
 531                         return -EFAULT;
 532 
 533                 if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 534                         return -EINVAL;
 535 
 536                 rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
 537                                       GFP_KERNEL);
 538                 if (!rdwr_pa)
 539                         return -ENOMEM;
 540 
 541                 p = compat_ptr(rdwr_arg.msgs);
 542                 for (i = 0; i < rdwr_arg.nmsgs; i++) {
 543                         struct i2c_msg32 umsg;
 544                         if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
 545                                 kfree(rdwr_pa);
 546                                 return -EFAULT;
 547                         }
 548                         rdwr_pa[i] = (struct i2c_msg) {
 549                                 .addr = umsg.addr,
 550                                 .flags = umsg.flags,
 551                                 .len = umsg.len,
 552                                 .buf = compat_ptr(umsg.buf)
 553                         };
 554                 }
 555 
 556                 return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
 557         }
 558         case I2C_SMBUS: {
 559                 struct i2c_smbus_ioctl_data32   data32;
 560                 if (copy_from_user(&data32,
 561                                    (void __user *) arg,
 562                                    sizeof(data32)))
 563                         return -EFAULT;
 564                 return i2cdev_ioctl_smbus(client, data32.read_write,
 565                                           data32.command,
 566                                           data32.size,
 567                                           compat_ptr(data32.data));
 568         }
 569         default:
 570                 return i2cdev_ioctl(file, cmd, arg);
 571         }
 572 }
 573 #else
 574 #define compat_i2cdev_ioctl NULL
 575 #endif
 576 
 577 static int i2cdev_open(struct inode *inode, struct file *file)
 578 {
 579         unsigned int minor = iminor(inode);
 580         struct i2c_client *client;
 581         struct i2c_adapter *adap;
 582 
 583         adap = i2c_get_adapter(minor);
 584         if (!adap)
 585                 return -ENODEV;
 586 
 587         /* This creates an anonymous i2c_client, which may later be
 588          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 589          *
 590          * This client is ** NEVER REGISTERED ** with the driver model
 591          * or I2C core code!!  It just holds private copies of addressing
 592          * information and maybe a PEC flag.
 593          */
 594         client = kzalloc(sizeof(*client), GFP_KERNEL);
 595         if (!client) {
 596                 i2c_put_adapter(adap);
 597                 return -ENOMEM;
 598         }
 599         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 600 
 601         client->adapter = adap;
 602         file->private_data = client;
 603 
 604         return 0;
 605 }
 606 
 607 static int i2cdev_release(struct inode *inode, struct file *file)
 608 {
 609         struct i2c_client *client = file->private_data;
 610 
 611         i2c_put_adapter(client->adapter);
 612         kfree(client);
 613         file->private_data = NULL;
 614 
 615         return 0;
 616 }
 617 
 618 static const struct file_operations i2cdev_fops = {
 619         .owner          = THIS_MODULE,
 620         .llseek         = no_llseek,
 621         .read           = i2cdev_read,
 622         .write          = i2cdev_write,
 623         .unlocked_ioctl = i2cdev_ioctl,
 624         .compat_ioctl   = compat_i2cdev_ioctl,
 625         .open           = i2cdev_open,
 626         .release        = i2cdev_release,
 627 };
 628 
 629 /* ------------------------------------------------------------------------- */
 630 
 631 static struct class *i2c_dev_class;
 632 
 633 static void i2cdev_dev_release(struct device *dev)
 634 {
 635         struct i2c_dev *i2c_dev;
 636 
 637         i2c_dev = container_of(dev, struct i2c_dev, dev);
 638         kfree(i2c_dev);
 639 }
 640 
 641 static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 642 {
 643         struct i2c_adapter *adap;
 644         struct i2c_dev *i2c_dev;
 645         int res;
 646 
 647         if (dev->type != &i2c_adapter_type)
 648                 return 0;
 649         adap = to_i2c_adapter(dev);
 650 
 651         i2c_dev = get_free_i2c_dev(adap);
 652         if (IS_ERR(i2c_dev))
 653                 return PTR_ERR(i2c_dev);
 654 
 655         cdev_init(&i2c_dev->cdev, &i2cdev_fops);
 656         i2c_dev->cdev.owner = THIS_MODULE;
 657 
 658         device_initialize(&i2c_dev->dev);
 659         i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
 660         i2c_dev->dev.class = i2c_dev_class;
 661         i2c_dev->dev.parent = &adap->dev;
 662         i2c_dev->dev.release = i2cdev_dev_release;
 663         dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
 664 
 665         res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
 666         if (res) {
 667                 put_i2c_dev(i2c_dev, false);
 668                 return res;
 669         }
 670 
 671         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 672                  adap->name, adap->nr);
 673         return 0;
 674 }
 675 
 676 static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 677 {
 678         struct i2c_adapter *adap;
 679         struct i2c_dev *i2c_dev;
 680 
 681         if (dev->type != &i2c_adapter_type)
 682                 return 0;
 683         adap = to_i2c_adapter(dev);
 684 
 685         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 686         if (!i2c_dev) /* attach_adapter must have failed */
 687                 return 0;
 688 
 689         put_i2c_dev(i2c_dev, true);
 690 
 691         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 692         return 0;
 693 }
 694 
 695 static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 696                          void *data)
 697 {
 698         struct device *dev = data;
 699 
 700         switch (action) {
 701         case BUS_NOTIFY_ADD_DEVICE:
 702                 return i2cdev_attach_adapter(dev, NULL);
 703         case BUS_NOTIFY_DEL_DEVICE:
 704                 return i2cdev_detach_adapter(dev, NULL);
 705         }
 706 
 707         return 0;
 708 }
 709 
 710 static struct notifier_block i2cdev_notifier = {
 711         .notifier_call = i2cdev_notifier_call,
 712 };
 713 
 714 /* ------------------------------------------------------------------------- */
 715 
 716 /*
 717  * module load/unload record keeping
 718  */
 719 
 720 static int __init i2c_dev_init(void)
 721 {
 722         int res;
 723 
 724         printk(KERN_INFO "i2c /dev entries driver\n");
 725 
 726         res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
 727         if (res)
 728                 goto out;
 729 
 730         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 731         if (IS_ERR(i2c_dev_class)) {
 732                 res = PTR_ERR(i2c_dev_class);
 733                 goto out_unreg_chrdev;
 734         }
 735         i2c_dev_class->dev_groups = i2c_groups;
 736 
 737         /* Keep track of adapters which will be added or removed later */
 738         res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 739         if (res)
 740                 goto out_unreg_class;
 741 
 742         /* Bind to already existing adapters right away */
 743         i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 744 
 745         return 0;
 746 
 747 out_unreg_class:
 748         class_destroy(i2c_dev_class);
 749 out_unreg_chrdev:
 750         unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 751 out:
 752         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 753         return res;
 754 }
 755 
 756 static void __exit i2c_dev_exit(void)
 757 {
 758         bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 759         i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 760         class_destroy(i2c_dev_class);
 761         unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 762 }
 763 
 764 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 765                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 766 MODULE_DESCRIPTION("I2C /dev entries driver");
 767 MODULE_LICENSE("GPL");
 768 
 769 module_init(i2c_dev_init);
 770 module_exit(i2c_dev_exit);
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root/drivers/i2c/i2c-dev.c

DEFINITIONS
