drivers/i2c/i2c-dev.c

   1 /*
   2     i2c-dev.c - i2c-bus driver, char device interface
   3
   4     Copyright (C) 1995-97 Simon G. Vogl
   5     Copyright (C) 1998-99 Frodo Looijaard <frodol@dds.nl>
   6     Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 /* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
  24    But I have used so much of his original code and ideas that it seems
  25    only fair to recognize him as co-author -- Frodo */
  26
  27 /* The I2C_RDWR ioctl code is written by Kolja Waschk <waschk@telos.de> */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/fs.h>
  32 #include <linux/slab.h>
  33 #include <linux/init.h>
  34 #include <linux/list.h>
  35 #include <linux/i2c.h>
  36 #include <linux/i2c-dev.h>
  37 #include <asm/uaccess.h>
  38
  39 static struct i2c_driver i2cdev_driver;
  40
  41 /*
  42  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  43  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  44  * with a character special file which is accessed by user mode drivers.
  45  *
  46  * The list of i2c_dev structures is parallel to the i2c_adapter lists
  47  * maintained by the driver model, and is updated using notifications
  48  * delivered to the i2cdev_driver.
  49  */
  50 struct i2c_dev {
  51         struct list_head list;
  52         struct i2c_adapter *adap;
  53         struct device *dev;
  54 };
  55
  56 #define I2C_MINORS      256
  57 static LIST_HEAD(i2c_dev_list);
  58 static DEFINE_SPINLOCK(i2c_dev_list_lock);
  59
  60 static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
  61 {
  62         struct i2c_dev *i2c_dev;
  63
  64         spin_lock(&i2c_dev_list_lock);
  65         list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
  66                 if (i2c_dev->adap->nr == index)
  67                         goto found;
  68         }
  69         i2c_dev = NULL;
  70 found:
  71         spin_unlock(&i2c_dev_list_lock);
  72         return i2c_dev;
  73 }
  74
  75 static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
  76 {
  77         struct i2c_dev *i2c_dev;
  78
  79         if (adap->nr >= I2C_MINORS) {
  80                 printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
  81                        adap->nr);
  82                 return ERR_PTR(-ENODEV);
  83         }
  84
  85         i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);
  86         if (!i2c_dev)
  87                 return ERR_PTR(-ENOMEM);
  88         i2c_dev->adap = adap;
  89
  90         spin_lock(&i2c_dev_list_lock);
  91         list_add_tail(&i2c_dev->list, &i2c_dev_list);
  92         spin_unlock(&i2c_dev_list_lock);
  93         return i2c_dev;
  94 }
  95
  96 static void return_i2c_dev(struct i2c_dev *i2c_dev)
  97 {
  98         spin_lock(&i2c_dev_list_lock);
  99         list_del(&i2c_dev->list);
 100         spin_unlock(&i2c_dev_list_lock);
 101         kfree(i2c_dev);
 102 }
 103
 104 static ssize_t show_adapter_name(struct device *dev,
 105                                  struct device_attribute *attr, char *buf)
 106 {
 107         struct i2c_dev *i2c_dev = i2c_dev_get_by_minor(MINOR(dev->devt));
 108
 109         if (!i2c_dev)
 110                 return -ENODEV;
 111         return sprintf(buf, "%s\n", i2c_dev->adap->name);
 112 }
 113 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
 114
 115 /* ------------------------------------------------------------------------- */
 116
 117 /*
 118  * After opening an instance of this character special file, a file
 119  * descriptor starts out associated only with an i2c_adapter (and bus).
 120  *
 121  * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
 122  * traffic to any devices on the bus used by that adapter.  That's because
 123  * the i2c_msg vectors embed all the addressing information they need, and
 124  * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
 125  * don't support that interface.
 126  *
 127  * To use read()/write() system calls on that file descriptor, or to use
 128  * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
 129  * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
 130  * (never registered) i2c_client so it holds the addressing information
 131  * needed by those system calls and by this SMBus interface.
 132  */
 133
 134 static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
 135                             loff_t *offset)
 136 {
 137         char *tmp;
 138         int ret;
 139
 140         struct i2c_client *client = (struct i2c_client *)file->private_data;
 141
 142         if (count > 8192)
 143                 count = 8192;
 144
 145         tmp = kmalloc(count,GFP_KERNEL);
 146         if (tmp==NULL)
 147                 return -ENOMEM;
 148
 149         pr_debug("i2c-dev: i2c-%d reading %zd bytes.\n",
 150                 iminor(file->f_path.dentry->d_inode), count);
 151
 152         ret = i2c_master_recv(client,tmp,count);
 153         if (ret >= 0)
 154                 ret = copy_to_user(buf,tmp,count)?-EFAULT:ret;
 155         kfree(tmp);
 156         return ret;
 157 }
 158
 159 static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t count,
 160                              loff_t *offset)
 161 {
 162         int ret;
 163         char *tmp;
 164         struct i2c_client *client = (struct i2c_client *)file->private_data;
 165
 166         if (count > 8192)
 167                 count = 8192;
 168
 169         tmp = kmalloc(count,GFP_KERNEL);
 170         if (tmp==NULL)
 171                 return -ENOMEM;
 172         if (copy_from_user(tmp,buf,count)) {
 173                 kfree(tmp);
 174                 return -EFAULT;
 175         }
 176
 177         pr_debug("i2c-dev: i2c-%d writing %zd bytes.\n",
 178                 iminor(file->f_path.dentry->d_inode), count);
 179
 180         ret = i2c_master_send(client,tmp,count);
 181         kfree(tmp);
 182         return ret;
 183 }
 184
 185 static int i2cdev_ioctl(struct inode *inode, struct file *file,
 186                 unsigned int cmd, unsigned long arg)
 187 {
 188         struct i2c_client *client = (struct i2c_client *)file->private_data;
 189         struct i2c_rdwr_ioctl_data rdwr_arg;
 190         struct i2c_smbus_ioctl_data data_arg;
 191         union i2c_smbus_data temp;
 192         struct i2c_msg *rdwr_pa;
 193         u8 __user **data_ptrs;
 194         int i,datasize,res;
 195         unsigned long funcs;
 196
 197         dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 198                 cmd, arg);
 199
 200         switch ( cmd ) {
 201         case I2C_SLAVE:
 202         case I2C_SLAVE_FORCE:
 203                 /* NOTE:  devices set up to work with "new style" drivers
 204                  * can't use I2C_SLAVE, even when the device node is not
 205                  * bound to a driver.  Only I2C_SLAVE_FORCE will work.
 206                  *
 207                  * Setting the PEC flag here won't affect kernel drivers,
 208                  * which will be using the i2c_client node registered with
 209                  * the driver model core.  Likewise, when that client has
 210                  * the PEC flag already set, the i2c-dev driver won't see
 211                  * (or use) this setting.
 212                  */
 213                 if ((arg > 0x3ff) ||
 214                     (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 215                         return -EINVAL;
 216                 if ((cmd == I2C_SLAVE) && i2c_check_addr(client->adapter,arg))
 217                         return -EBUSY;
 218                 client->addr = arg;
 219                 return 0;
 220         case I2C_TENBIT:
 221                 if (arg)
 222                         client->flags |= I2C_M_TEN;
 223                 else
 224                         client->flags &= ~I2C_M_TEN;
 225                 return 0;
 226         case I2C_PEC:
 227                 if (arg)
 228                         client->flags |= I2C_CLIENT_PEC;
 229                 else
 230                         client->flags &= ~I2C_CLIENT_PEC;
 231                 return 0;
 232         case I2C_FUNCS:
 233                 funcs = i2c_get_functionality(client->adapter);
 234                 return put_user(funcs, (unsigned long __user *)arg);
 235
 236         case I2C_RDWR:
 237                 if (copy_from_user(&rdwr_arg,
 238                                    (struct i2c_rdwr_ioctl_data __user *)arg,
 239                                    sizeof(rdwr_arg)))
 240                         return -EFAULT;
 241
 242                 /* Put an arbitrary limit on the number of messages that can
 243                  * be sent at once */
 244                 if (rdwr_arg.nmsgs > I2C_RDRW_IOCTL_MAX_MSGS)
 245                         return -EINVAL;
 246
 247                 rdwr_pa = (struct i2c_msg *)
 248                         kmalloc(rdwr_arg.nmsgs * sizeof(struct i2c_msg),
 249                         GFP_KERNEL);
 250
 251                 if (rdwr_pa == NULL) return -ENOMEM;
 252
 253                 if (copy_from_user(rdwr_pa, rdwr_arg.msgs,
 254                                    rdwr_arg.nmsgs * sizeof(struct i2c_msg))) {
 255                         kfree(rdwr_pa);
 256                         return -EFAULT;
 257                 }
 258
 259                 data_ptrs = kmalloc(rdwr_arg.nmsgs * sizeof(u8 __user *), GFP_KERNEL);
 260                 if (data_ptrs == NULL) {
 261                         kfree(rdwr_pa);
 262                         return -ENOMEM;
 263                 }
 264
 265                 res = 0;
 266                 for( i=0; i<rdwr_arg.nmsgs; i++ ) {
 267                         /* Limit the size of the message to a sane amount;
 268                          * and don't let length change either. */
 269                         if ((rdwr_pa[i].len > 8192) ||
 270                             (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
 271                                 res = -EINVAL;
 272                                 break;
 273                         }
 274                         data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 275                         rdwr_pa[i].buf = kmalloc(rdwr_pa[i].len, GFP_KERNEL);
 276                         if(rdwr_pa[i].buf == NULL) {
 277                                 res = -ENOMEM;
 278                                 break;
 279                         }
 280                         if(copy_from_user(rdwr_pa[i].buf,
 281                                 data_ptrs[i],
 282                                 rdwr_pa[i].len)) {
 283                                         ++i; /* Needs to be kfreed too */
 284                                         res = -EFAULT;
 285                                 break;
 286                         }
 287                 }
 288                 if (res < 0) {
 289                         int j;
 290                         for (j = 0; j < i; ++j)
 291                                 kfree(rdwr_pa[j].buf);
 292                         kfree(data_ptrs);
 293                         kfree(rdwr_pa);
 294                         return res;
 295                 }
 296
 297                 res = i2c_transfer(client->adapter,
 298                         rdwr_pa,
 299                         rdwr_arg.nmsgs);
 300                 while(i-- > 0) {
 301                         if( res>=0 && (rdwr_pa[i].flags & I2C_M_RD)) {
 302                                 if(copy_to_user(
 303                                         data_ptrs[i],
 304                                         rdwr_pa[i].buf,
 305                                         rdwr_pa[i].len)) {
 306                                         res = -EFAULT;
 307                                 }
 308                         }
 309                         kfree(rdwr_pa[i].buf);
 310                 }
 311                 kfree(data_ptrs);
 312                 kfree(rdwr_pa);
 313                 return res;
 314
 315         case I2C_SMBUS:
 316                 if (copy_from_user(&data_arg,
 317                                    (struct i2c_smbus_ioctl_data __user *) arg,
 318                                    sizeof(struct i2c_smbus_ioctl_data)))
 319                         return -EFAULT;
 320                 if ((data_arg.size != I2C_SMBUS_BYTE) &&
 321                     (data_arg.size != I2C_SMBUS_QUICK) &&
 322                     (data_arg.size != I2C_SMBUS_BYTE_DATA) &&
 323                     (data_arg.size != I2C_SMBUS_WORD_DATA) &&
 324                     (data_arg.size != I2C_SMBUS_PROC_CALL) &&
 325                     (data_arg.size != I2C_SMBUS_BLOCK_DATA) &&
 326                     (data_arg.size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 327                     (data_arg.size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 328                     (data_arg.size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 329                         dev_dbg(&client->adapter->dev,
 330                                 "size out of range (%x) in ioctl I2C_SMBUS.\n",
 331                                 data_arg.size);
 332                         return -EINVAL;
 333                 }
 334                 /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 335                    so the check is valid if size==I2C_SMBUS_QUICK too. */
 336                 if ((data_arg.read_write != I2C_SMBUS_READ) &&
 337                     (data_arg.read_write != I2C_SMBUS_WRITE)) {
 338                         dev_dbg(&client->adapter->dev,
 339                                 "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 340                                 data_arg.read_write);
 341                         return -EINVAL;
 342                 }
 343
 344                 /* Note that command values are always valid! */
 345
 346                 if ((data_arg.size == I2C_SMBUS_QUICK) ||
 347                     ((data_arg.size == I2C_SMBUS_BYTE) &&
 348                     (data_arg.read_write == I2C_SMBUS_WRITE)))
 349                         /* These are special: we do not use data */
 350                         return i2c_smbus_xfer(client->adapter, client->addr,
 351                                               client->flags,
 352                                               data_arg.read_write,
 353                                               data_arg.command,
 354                                               data_arg.size, NULL);
 355
 356                 if (data_arg.data == NULL) {
 357                         dev_dbg(&client->adapter->dev,
 358                                 "data is NULL pointer in ioctl I2C_SMBUS.\n");
 359                         return -EINVAL;
 360                 }
 361
 362                 if ((data_arg.size == I2C_SMBUS_BYTE_DATA) ||
 363                     (data_arg.size == I2C_SMBUS_BYTE))
 364                         datasize = sizeof(data_arg.data->byte);
 365                 else if ((data_arg.size == I2C_SMBUS_WORD_DATA) ||
 366                          (data_arg.size == I2C_SMBUS_PROC_CALL))
 367                         datasize = sizeof(data_arg.data->word);
 368                 else /* size == smbus block, i2c block, or block proc. call */
 369                         datasize = sizeof(data_arg.data->block);
 370
 371                 if ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 372                     (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 373                     (data_arg.size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 374                     (data_arg.read_write == I2C_SMBUS_WRITE)) {
 375                         if (copy_from_user(&temp, data_arg.data, datasize))
 376                                 return -EFAULT;
 377                 }
 378                 if (data_arg.size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 379                         /* Convert old I2C block commands to the new
 380                            convention. This preserves binary compatibility. */
 381                         data_arg.size = I2C_SMBUS_I2C_BLOCK_DATA;
 382                         if (data_arg.read_write == I2C_SMBUS_READ)
 383                                 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 384                 }
 385                 res = i2c_smbus_xfer(client->adapter,client->addr,client->flags,
 386                       data_arg.read_write,
 387                       data_arg.command,data_arg.size,&temp);
 388                 if (! res && ((data_arg.size == I2C_SMBUS_PROC_CALL) ||
 389                               (data_arg.size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 390                               (data_arg.read_write == I2C_SMBUS_READ))) {
 391                         if (copy_to_user(data_arg.data, &temp, datasize))
 392                                 return -EFAULT;
 393                 }
 394                 return res;
 395         case I2C_RETRIES:
 396                 client->adapter->retries = arg;
 397                 break;
 398         case I2C_TIMEOUT:
 399                 client->adapter->timeout = arg;
 400                 break;
 401         default:
 402                 /* NOTE:  returning a fault code here could cause trouble
 403                  * in buggy userspace code.  Some old kernel bugs returned
 404                  * zero in this case, and userspace code might accidentally
 405                  * have depended on that bug.
 406                  */
 407                 return -ENOTTY;
 408         }
 409         return 0;
 410 }
 411
 412 static int i2cdev_open(struct inode *inode, struct file *file)
 413 {
 414         unsigned int minor = iminor(inode);
 415         struct i2c_client *client;
 416         struct i2c_adapter *adap;
 417         struct i2c_dev *i2c_dev;
 418
 419         i2c_dev = i2c_dev_get_by_minor(minor);
 420         if (!i2c_dev)
 421                 return -ENODEV;
 422
 423         adap = i2c_get_adapter(i2c_dev->adap->nr);
 424         if (!adap)
 425                 return -ENODEV;
 426
 427         /* This creates an anonymous i2c_client, which may later be
 428          * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 429          *
 430          * This client is ** NEVER REGISTERED ** with the driver model
 431          * or I2C core code!!  It just holds private copies of addressing
 432          * information and maybe a PEC flag.
 433          */
 434         client = kzalloc(sizeof(*client), GFP_KERNEL);
 435         if (!client) {
 436                 i2c_put_adapter(adap);
 437                 return -ENOMEM;
 438         }
 439         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 440         client->driver = &i2cdev_driver;
 441
 442         client->adapter = adap;
 443         file->private_data = client;
 444
 445         return 0;
 446 }
 447
 448 static int i2cdev_release(struct inode *inode, struct file *file)
 449 {
 450         struct i2c_client *client = file->private_data;
 451
 452         i2c_put_adapter(client->adapter);
 453         kfree(client);
 454         file->private_data = NULL;
 455
 456         return 0;
 457 }
 458
 459 static const struct file_operations i2cdev_fops = {
 460         .owner          = THIS_MODULE,
 461         .llseek         = no_llseek,
 462         .read           = i2cdev_read,
 463         .write          = i2cdev_write,
 464         .ioctl          = i2cdev_ioctl,
 465         .open           = i2cdev_open,
 466         .release        = i2cdev_release,
 467 };
 468
 469 /* ------------------------------------------------------------------------- */
 470
 471 /*
 472  * The legacy "i2cdev_driver" is used primarily to get notifications when
 473  * I2C adapters are added or removed, so that each one gets an i2c_dev
 474  * and is thus made available to userspace driver code.
 475  */
 476
 477 static struct class *i2c_dev_class;
 478
 479 static int i2cdev_attach_adapter(struct i2c_adapter *adap)
 480 {
 481         struct i2c_dev *i2c_dev;
 482         int res;
 483
 484         i2c_dev = get_free_i2c_dev(adap);
 485         if (IS_ERR(i2c_dev))
 486                 return PTR_ERR(i2c_dev);
 487
 488         /* register this i2c device with the driver core */
 489         i2c_dev->dev = device_create(i2c_dev_class, &adap->dev,
 490                                      MKDEV(I2C_MAJOR, adap->nr),
 491                                      "i2c-%d", adap->nr);
 492         if (IS_ERR(i2c_dev->dev)) {
 493                 res = PTR_ERR(i2c_dev->dev);
 494                 goto error;
 495         }
 496         res = device_create_file(i2c_dev->dev, &dev_attr_name);
 497         if (res)
 498                 goto error_destroy;
 499
 500         pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 501                  adap->name, adap->nr);
 502         return 0;
 503 error_destroy:
 504         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 505 error:
 506         return_i2c_dev(i2c_dev);
 507         return res;
 508 }
 509
 510 static int i2cdev_detach_adapter(struct i2c_adapter *adap)
 511 {
 512         struct i2c_dev *i2c_dev;
 513
 514         i2c_dev = i2c_dev_get_by_minor(adap->nr);
 515         if (!i2c_dev) /* attach_adapter must have failed */
 516                 return 0;
 517
 518         device_remove_file(i2c_dev->dev, &dev_attr_name);
 519         return_i2c_dev(i2c_dev);
 520         device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 521
 522         pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 523         return 0;
 524 }
 525
 526 static int i2cdev_detach_client(struct i2c_client *client)
 527 {
 528         return 0;
 529 }
 530
 531 static struct i2c_driver i2cdev_driver = {
 532         .driver = {
 533                 .name   = "dev_driver",
 534         },
 535         .id             = I2C_DRIVERID_I2CDEV,
 536         .attach_adapter = i2cdev_attach_adapter,
 537         .detach_adapter = i2cdev_detach_adapter,
 538         .detach_client  = i2cdev_detach_client,
 539 };
 540
 541 /* ------------------------------------------------------------------------- */
 542
 543 /*
 544  * module load/unload record keeping
 545  */
 546
 547 static int __init i2c_dev_init(void)
 548 {
 549         int res;
 550
 551         printk(KERN_INFO "i2c /dev entries driver\n");
 552
 553         res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops);
 554         if (res)
 555                 goto out;
 556
 557         i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 558         if (IS_ERR(i2c_dev_class))
 559                 goto out_unreg_chrdev;
 560
 561         res = i2c_add_driver(&i2cdev_driver);
 562         if (res)
 563                 goto out_unreg_class;
 564
 565         return 0;
 566
 567 out_unreg_class:
 568         class_destroy(i2c_dev_class);
 569 out_unreg_chrdev:
 570         unregister_chrdev(I2C_MAJOR, "i2c");
 571 out:
 572         printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 573         return res;
 574 }
 575
 576 static void __exit i2c_dev_exit(void)
 577 {
 578         i2c_del_driver(&i2cdev_driver);
 579         class_destroy(i2c_dev_class);
 580         unregister_chrdev(I2C_MAJOR,"i2c");
 581 }
 582
 583 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 584                 "Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 585 MODULE_DESCRIPTION("I2C /dev entries driver");
 586 MODULE_LICENSE("GPL");
 587
 588 module_init(i2c_dev_init);
 589 module_exit(i2c_dev_exit);