linux/drivers/i2c/i2c-dev.c
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   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/compat.h>
  19#include <linux/device.h>
  20#include <linux/fs.h>
  21#include <linux/i2c-dev.h>
  22#include <linux/i2c.h>
  23#include <linux/init.h>
  24#include <linux/jiffies.h>
  25#include <linux/kernel.h>
  26#include <linux/list.h>
  27#include <linux/module.h>
  28#include <linux/notifier.h>
  29#include <linux/slab.h>
  30#include <linux/uaccess.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 */
  40struct 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)
  48static LIST_HEAD(i2c_dev_list);
  49static DEFINE_SPINLOCK(i2c_dev_list_lock);
  50
  51static 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;
  61found:
  62        spin_unlock(&i2c_dev_list_lock);
  63        return i2c_dev;
  64}
  65
  66static 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
  87static 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
  97static 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}
 106static DEVICE_ATTR_RO(name);
 107
 108static struct attribute *i2c_attrs[] = {
 109        &dev_attr_name.attr,
 110        NULL,
 111};
 112ATTRIBUTE_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
 133static 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 = kzalloc(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                if (copy_to_user(buf, tmp, ret))
 154                        ret = -EFAULT;
 155        kfree(tmp);
 156        return ret;
 157}
 158
 159static ssize_t i2cdev_write(struct file *file, const char __user *buf,
 160                size_t count, loff_t *offset)
 161{
 162        int ret;
 163        char *tmp;
 164        struct i2c_client *client = file->private_data;
 165
 166        if (count > 8192)
 167                count = 8192;
 168
 169        tmp = memdup_user(buf, count);
 170        if (IS_ERR(tmp))
 171                return PTR_ERR(tmp);
 172
 173        pr_debug("i2c-dev: i2c-%d writing %zu bytes.\n",
 174                iminor(file_inode(file)), count);
 175
 176        ret = i2c_master_send(client, tmp, count);
 177        kfree(tmp);
 178        return ret;
 179}
 180
 181static int i2cdev_check(struct device *dev, void *addrp)
 182{
 183        struct i2c_client *client = i2c_verify_client(dev);
 184
 185        if (!client || client->addr != *(unsigned int *)addrp)
 186                return 0;
 187
 188        return dev->driver ? -EBUSY : 0;
 189}
 190
 191/* walk up mux tree */
 192static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 193{
 194        struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 195        int result;
 196
 197        result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
 198        if (!result && parent)
 199                result = i2cdev_check_mux_parents(parent, addr);
 200
 201        return result;
 202}
 203
 204/* recurse down mux tree */
 205static int i2cdev_check_mux_children(struct device *dev, void *addrp)
 206{
 207        int result;
 208
 209        if (dev->type == &i2c_adapter_type)
 210                result = device_for_each_child(dev, addrp,
 211                                                i2cdev_check_mux_children);
 212        else
 213                result = i2cdev_check(dev, addrp);
 214
 215        return result;
 216}
 217
 218/* This address checking function differs from the one in i2c-core
 219   in that it considers an address with a registered device, but no
 220   driver bound to it, as NOT busy. */
 221static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 222{
 223        struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 224        int result = 0;
 225
 226        if (parent)
 227                result = i2cdev_check_mux_parents(parent, addr);
 228
 229        if (!result)
 230                result = device_for_each_child(&adapter->dev, &addr,
 231                                                i2cdev_check_mux_children);
 232
 233        return result;
 234}
 235
 236static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
 237                unsigned nmsgs, struct i2c_msg *msgs)
 238{
 239        u8 __user **data_ptrs;
 240        int i, res;
 241
 242        data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
 243        if (data_ptrs == NULL) {
 244                kfree(msgs);
 245                return -ENOMEM;
 246        }
 247
 248        res = 0;
 249        for (i = 0; i < nmsgs; i++) {
 250                /* Limit the size of the message to a sane amount */
 251                if (msgs[i].len > 8192) {
 252                        res = -EINVAL;
 253                        break;
 254                }
 255
 256                data_ptrs[i] = (u8 __user *)msgs[i].buf;
 257                msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
 258                if (IS_ERR(msgs[i].buf)) {
 259                        res = PTR_ERR(msgs[i].buf);
 260                        break;
 261                }
 262                /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
 263                msgs[i].flags |= I2C_M_DMA_SAFE;
 264
 265                /*
 266                 * If the message length is received from the slave (similar
 267                 * to SMBus block read), we must ensure that the buffer will
 268                 * be large enough to cope with a message length of
 269                 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
 270                 * drivers allow. The first byte in the buffer must be
 271                 * pre-filled with the number of extra bytes, which must be
 272                 * at least one to hold the message length, but can be
 273                 * greater (for example to account for a checksum byte at
 274                 * the end of the message.)
 275                 */
 276                if (msgs[i].flags & I2C_M_RECV_LEN) {
 277                        if (!(msgs[i].flags & I2C_M_RD) ||
 278                            msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
 279                            msgs[i].len < msgs[i].buf[0] +
 280                                             I2C_SMBUS_BLOCK_MAX) {
 281                                i++;
 282                                res = -EINVAL;
 283                                break;
 284                        }
 285
 286                        msgs[i].len = msgs[i].buf[0];
 287                }
 288        }
 289        if (res < 0) {
 290                int j;
 291                for (j = 0; j < i; ++j)
 292                        kfree(msgs[j].buf);
 293                kfree(data_ptrs);
 294                kfree(msgs);
 295                return res;
 296        }
 297
 298        res = i2c_transfer(client->adapter, msgs, nmsgs);
 299        while (i-- > 0) {
 300                if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
 301                        if (copy_to_user(data_ptrs[i], msgs[i].buf,
 302                                         msgs[i].len))
 303                                res = -EFAULT;
 304                }
 305                kfree(msgs[i].buf);
 306        }
 307        kfree(data_ptrs);
 308        kfree(msgs);
 309        return res;
 310}
 311
 312static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
 313                u8 read_write, u8 command, u32 size,
 314                union i2c_smbus_data __user *data)
 315{
 316        union i2c_smbus_data temp = {};
 317        int datasize, res;
 318
 319        if ((size != I2C_SMBUS_BYTE) &&
 320            (size != I2C_SMBUS_QUICK) &&
 321            (size != I2C_SMBUS_BYTE_DATA) &&
 322            (size != I2C_SMBUS_WORD_DATA) &&
 323            (size != I2C_SMBUS_PROC_CALL) &&
 324            (size != I2C_SMBUS_BLOCK_DATA) &&
 325            (size != I2C_SMBUS_I2C_BLOCK_BROKEN) &&
 326            (size != I2C_SMBUS_I2C_BLOCK_DATA) &&
 327            (size != I2C_SMBUS_BLOCK_PROC_CALL)) {
 328                dev_dbg(&client->adapter->dev,
 329                        "size out of range (%x) in ioctl I2C_SMBUS.\n",
 330                        size);
 331                return -EINVAL;
 332        }
 333        /* Note that I2C_SMBUS_READ and I2C_SMBUS_WRITE are 0 and 1,
 334           so the check is valid if size==I2C_SMBUS_QUICK too. */
 335        if ((read_write != I2C_SMBUS_READ) &&
 336            (read_write != I2C_SMBUS_WRITE)) {
 337                dev_dbg(&client->adapter->dev,
 338                        "read_write out of range (%x) in ioctl I2C_SMBUS.\n",
 339                        read_write);
 340                return -EINVAL;
 341        }
 342
 343        /* Note that command values are always valid! */
 344
 345        if ((size == I2C_SMBUS_QUICK) ||
 346            ((size == I2C_SMBUS_BYTE) &&
 347            (read_write == I2C_SMBUS_WRITE)))
 348                /* These are special: we do not use data */
 349                return i2c_smbus_xfer(client->adapter, client->addr,
 350                                      client->flags, read_write,
 351                                      command, size, NULL);
 352
 353        if (data == NULL) {
 354                dev_dbg(&client->adapter->dev,
 355                        "data is NULL pointer in ioctl I2C_SMBUS.\n");
 356                return -EINVAL;
 357        }
 358
 359        if ((size == I2C_SMBUS_BYTE_DATA) ||
 360            (size == I2C_SMBUS_BYTE))
 361                datasize = sizeof(data->byte);
 362        else if ((size == I2C_SMBUS_WORD_DATA) ||
 363                 (size == I2C_SMBUS_PROC_CALL))
 364                datasize = sizeof(data->word);
 365        else /* size == smbus block, i2c block, or block proc. call */
 366                datasize = sizeof(data->block);
 367
 368        if ((size == I2C_SMBUS_PROC_CALL) ||
 369            (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 370            (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
 371            (read_write == I2C_SMBUS_WRITE)) {
 372                if (copy_from_user(&temp, data, datasize))
 373                        return -EFAULT;
 374        }
 375        if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
 376                /* Convert old I2C block commands to the new
 377                   convention. This preserves binary compatibility. */
 378                size = I2C_SMBUS_I2C_BLOCK_DATA;
 379                if (read_write == I2C_SMBUS_READ)
 380                        temp.block[0] = I2C_SMBUS_BLOCK_MAX;
 381        }
 382        res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
 383              read_write, command, size, &temp);
 384        if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
 385                     (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
 386                     (read_write == I2C_SMBUS_READ))) {
 387                if (copy_to_user(data, &temp, datasize))
 388                        return -EFAULT;
 389        }
 390        return res;
 391}
 392
 393static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 394{
 395        struct i2c_client *client = file->private_data;
 396        unsigned long funcs;
 397
 398        dev_dbg(&client->adapter->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
 399                cmd, arg);
 400
 401        switch (cmd) {
 402        case I2C_SLAVE:
 403        case I2C_SLAVE_FORCE:
 404                if ((arg > 0x3ff) ||
 405                    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 406                        return -EINVAL;
 407                if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 408                        return -EBUSY;
 409                /* REVISIT: address could become busy later */
 410                client->addr = arg;
 411                return 0;
 412        case I2C_TENBIT:
 413                if (arg)
 414                        client->flags |= I2C_M_TEN;
 415                else
 416                        client->flags &= ~I2C_M_TEN;
 417                return 0;
 418        case I2C_PEC:
 419                /*
 420                 * Setting the PEC flag here won't affect kernel drivers,
 421                 * which will be using the i2c_client node registered with
 422                 * the driver model core.  Likewise, when that client has
 423                 * the PEC flag already set, the i2c-dev driver won't see
 424                 * (or use) this setting.
 425                 */
 426                if (arg)
 427                        client->flags |= I2C_CLIENT_PEC;
 428                else
 429                        client->flags &= ~I2C_CLIENT_PEC;
 430                return 0;
 431        case I2C_FUNCS:
 432                funcs = i2c_get_functionality(client->adapter);
 433                return put_user(funcs, (unsigned long __user *)arg);
 434
 435        case I2C_RDWR: {
 436                struct i2c_rdwr_ioctl_data rdwr_arg;
 437                struct i2c_msg *rdwr_pa;
 438
 439                if (copy_from_user(&rdwr_arg,
 440                                   (struct i2c_rdwr_ioctl_data __user *)arg,
 441                                   sizeof(rdwr_arg)))
 442                        return -EFAULT;
 443
 444                if (!rdwr_arg.msgs || rdwr_arg.nmsgs == 0)
 445                        return -EINVAL;
 446
 447                /*
 448                 * Put an arbitrary limit on the number of messages that can
 449                 * be sent at once
 450                 */
 451                if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 452                        return -EINVAL;
 453
 454                rdwr_pa = memdup_user(rdwr_arg.msgs,
 455                                      rdwr_arg.nmsgs * sizeof(struct i2c_msg));
 456                if (IS_ERR(rdwr_pa))
 457                        return PTR_ERR(rdwr_pa);
 458
 459                return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
 460        }
 461
 462        case I2C_SMBUS: {
 463                struct i2c_smbus_ioctl_data data_arg;
 464                if (copy_from_user(&data_arg,
 465                                   (struct i2c_smbus_ioctl_data __user *) arg,
 466                                   sizeof(struct i2c_smbus_ioctl_data)))
 467                        return -EFAULT;
 468                return i2cdev_ioctl_smbus(client, data_arg.read_write,
 469                                          data_arg.command,
 470                                          data_arg.size,
 471                                          data_arg.data);
 472        }
 473        case I2C_RETRIES:
 474                if (arg > INT_MAX)
 475                        return -EINVAL;
 476
 477                client->adapter->retries = arg;
 478                break;
 479        case I2C_TIMEOUT:
 480                if (arg > INT_MAX)
 481                        return -EINVAL;
 482
 483                /* For historical reasons, user-space sets the timeout
 484                 * value in units of 10 ms.
 485                 */
 486                client->adapter->timeout = msecs_to_jiffies(arg * 10);
 487                break;
 488        default:
 489                /* NOTE:  returning a fault code here could cause trouble
 490                 * in buggy userspace code.  Some old kernel bugs returned
 491                 * zero in this case, and userspace code might accidentally
 492                 * have depended on that bug.
 493                 */
 494                return -ENOTTY;
 495        }
 496        return 0;
 497}
 498
 499#ifdef CONFIG_COMPAT
 500
 501struct i2c_smbus_ioctl_data32 {
 502        u8 read_write;
 503        u8 command;
 504        u32 size;
 505        compat_caddr_t data; /* union i2c_smbus_data *data */
 506};
 507
 508struct i2c_msg32 {
 509        u16 addr;
 510        u16 flags;
 511        u16 len;
 512        compat_caddr_t buf;
 513};
 514
 515struct i2c_rdwr_ioctl_data32 {
 516        compat_caddr_t msgs; /* struct i2c_msg __user *msgs */
 517        u32 nmsgs;
 518};
 519
 520static long compat_i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 521{
 522        struct i2c_client *client = file->private_data;
 523        unsigned long funcs;
 524        switch (cmd) {
 525        case I2C_FUNCS:
 526                funcs = i2c_get_functionality(client->adapter);
 527                return put_user(funcs, (compat_ulong_t __user *)arg);
 528        case I2C_RDWR: {
 529                struct i2c_rdwr_ioctl_data32 rdwr_arg;
 530                struct i2c_msg32 __user *p;
 531                struct i2c_msg *rdwr_pa;
 532                int i;
 533
 534                if (copy_from_user(&rdwr_arg,
 535                                   (struct i2c_rdwr_ioctl_data32 __user *)arg,
 536                                   sizeof(rdwr_arg)))
 537                        return -EFAULT;
 538
 539                if (rdwr_arg.nmsgs > I2C_RDWR_IOCTL_MAX_MSGS)
 540                        return -EINVAL;
 541
 542                rdwr_pa = kmalloc_array(rdwr_arg.nmsgs, sizeof(struct i2c_msg),
 543                                      GFP_KERNEL);
 544                if (!rdwr_pa)
 545                        return -ENOMEM;
 546
 547                p = compat_ptr(rdwr_arg.msgs);
 548                for (i = 0; i < rdwr_arg.nmsgs; i++) {
 549                        struct i2c_msg32 umsg;
 550                        if (copy_from_user(&umsg, p + i, sizeof(umsg))) {
 551                                kfree(rdwr_pa);
 552                                return -EFAULT;
 553                        }
 554                        rdwr_pa[i] = (struct i2c_msg) {
 555                                .addr = umsg.addr,
 556                                .flags = umsg.flags,
 557                                .len = umsg.len,
 558                                .buf = compat_ptr(umsg.buf)
 559                        };
 560                }
 561
 562                return i2cdev_ioctl_rdwr(client, rdwr_arg.nmsgs, rdwr_pa);
 563        }
 564        case I2C_SMBUS: {
 565                struct i2c_smbus_ioctl_data32   data32;
 566                if (copy_from_user(&data32,
 567                                   (void __user *) arg,
 568                                   sizeof(data32)))
 569                        return -EFAULT;
 570                return i2cdev_ioctl_smbus(client, data32.read_write,
 571                                          data32.command,
 572                                          data32.size,
 573                                          compat_ptr(data32.data));
 574        }
 575        default:
 576                return i2cdev_ioctl(file, cmd, arg);
 577        }
 578}
 579#else
 580#define compat_i2cdev_ioctl NULL
 581#endif
 582
 583static int i2cdev_open(struct inode *inode, struct file *file)
 584{
 585        unsigned int minor = iminor(inode);
 586        struct i2c_client *client;
 587        struct i2c_adapter *adap;
 588
 589        adap = i2c_get_adapter(minor);
 590        if (!adap)
 591                return -ENODEV;
 592
 593        /* This creates an anonymous i2c_client, which may later be
 594         * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
 595         *
 596         * This client is ** NEVER REGISTERED ** with the driver model
 597         * or I2C core code!!  It just holds private copies of addressing
 598         * information and maybe a PEC flag.
 599         */
 600        client = kzalloc(sizeof(*client), GFP_KERNEL);
 601        if (!client) {
 602                i2c_put_adapter(adap);
 603                return -ENOMEM;
 604        }
 605        snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 606
 607        client->adapter = adap;
 608        file->private_data = client;
 609
 610        return 0;
 611}
 612
 613static int i2cdev_release(struct inode *inode, struct file *file)
 614{
 615        struct i2c_client *client = file->private_data;
 616
 617        i2c_put_adapter(client->adapter);
 618        kfree(client);
 619        file->private_data = NULL;
 620
 621        return 0;
 622}
 623
 624static const struct file_operations i2cdev_fops = {
 625        .owner          = THIS_MODULE,
 626        .llseek         = no_llseek,
 627        .read           = i2cdev_read,
 628        .write          = i2cdev_write,
 629        .unlocked_ioctl = i2cdev_ioctl,
 630        .compat_ioctl   = compat_i2cdev_ioctl,
 631        .open           = i2cdev_open,
 632        .release        = i2cdev_release,
 633};
 634
 635/* ------------------------------------------------------------------------- */
 636
 637static struct class *i2c_dev_class;
 638
 639static void i2cdev_dev_release(struct device *dev)
 640{
 641        struct i2c_dev *i2c_dev;
 642
 643        i2c_dev = container_of(dev, struct i2c_dev, dev);
 644        kfree(i2c_dev);
 645}
 646
 647static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 648{
 649        struct i2c_adapter *adap;
 650        struct i2c_dev *i2c_dev;
 651        int res;
 652
 653        if (dev->type != &i2c_adapter_type)
 654                return 0;
 655        adap = to_i2c_adapter(dev);
 656
 657        i2c_dev = get_free_i2c_dev(adap);
 658        if (IS_ERR(i2c_dev))
 659                return PTR_ERR(i2c_dev);
 660
 661        cdev_init(&i2c_dev->cdev, &i2cdev_fops);
 662        i2c_dev->cdev.owner = THIS_MODULE;
 663
 664        device_initialize(&i2c_dev->dev);
 665        i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
 666        i2c_dev->dev.class = i2c_dev_class;
 667        i2c_dev->dev.parent = &adap->dev;
 668        i2c_dev->dev.release = i2cdev_dev_release;
 669        dev_set_name(&i2c_dev->dev, "i2c-%d", adap->nr);
 670
 671        res = cdev_device_add(&i2c_dev->cdev, &i2c_dev->dev);
 672        if (res) {
 673                put_i2c_dev(i2c_dev, false);
 674                return res;
 675        }
 676
 677        pr_debug("i2c-dev: adapter [%s] registered as minor %d\n",
 678                 adap->name, adap->nr);
 679        return 0;
 680}
 681
 682static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 683{
 684        struct i2c_adapter *adap;
 685        struct i2c_dev *i2c_dev;
 686
 687        if (dev->type != &i2c_adapter_type)
 688                return 0;
 689        adap = to_i2c_adapter(dev);
 690
 691        i2c_dev = i2c_dev_get_by_minor(adap->nr);
 692        if (!i2c_dev) /* attach_adapter must have failed */
 693                return 0;
 694
 695        put_i2c_dev(i2c_dev, true);
 696
 697        pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 698        return 0;
 699}
 700
 701static int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
 702                         void *data)
 703{
 704        struct device *dev = data;
 705
 706        switch (action) {
 707        case BUS_NOTIFY_ADD_DEVICE:
 708                return i2cdev_attach_adapter(dev, NULL);
 709        case BUS_NOTIFY_DEL_DEVICE:
 710                return i2cdev_detach_adapter(dev, NULL);
 711        }
 712
 713        return 0;
 714}
 715
 716static struct notifier_block i2cdev_notifier = {
 717        .notifier_call = i2cdev_notifier_call,
 718};
 719
 720/* ------------------------------------------------------------------------- */
 721
 722/*
 723 * module load/unload record keeping
 724 */
 725
 726static int __init i2c_dev_init(void)
 727{
 728        int res;
 729
 730        printk(KERN_INFO "i2c /dev entries driver\n");
 731
 732        res = register_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS, "i2c");
 733        if (res)
 734                goto out;
 735
 736        i2c_dev_class = class_create(THIS_MODULE, "i2c-dev");
 737        if (IS_ERR(i2c_dev_class)) {
 738                res = PTR_ERR(i2c_dev_class);
 739                goto out_unreg_chrdev;
 740        }
 741        i2c_dev_class->dev_groups = i2c_groups;
 742
 743        /* Keep track of adapters which will be added or removed later */
 744        res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
 745        if (res)
 746                goto out_unreg_class;
 747
 748        /* Bind to already existing adapters right away */
 749        i2c_for_each_dev(NULL, i2cdev_attach_adapter);
 750
 751        return 0;
 752
 753out_unreg_class:
 754        class_destroy(i2c_dev_class);
 755out_unreg_chrdev:
 756        unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 757out:
 758        printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
 759        return res;
 760}
 761
 762static void __exit i2c_dev_exit(void)
 763{
 764        bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 765        i2c_for_each_dev(NULL, i2cdev_detach_adapter);
 766        class_destroy(i2c_dev_class);
 767        unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 768}
 769
 770MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
 771MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 772MODULE_DESCRIPTION("I2C /dev entries driver");
 773MODULE_LICENSE("GPL");
 774
 775module_init(i2c_dev_init);
 776module_exit(i2c_dev_exit);
 777