drivers/spi/spidev.c

   1 /*
   2  * Simple synchronous userspace interface to SPI devices
   3  *
   4  * Copyright (C) 2006 SWAPP
   5  *      Andrea Paterniani <a.paterniani@swapp-eng.it>
   6  * Copyright (C) 2007 David Brownell (simplification, cleanup)
   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 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/ioctl.h>
  26 #include <linux/fs.h>
  27 #include <linux/device.h>
  28 #include <linux/err.h>
  29 #include <linux/list.h>
  30 #include <linux/errno.h>
  31 #include <linux/mutex.h>
  32 #include <linux/slab.h>
  33 #include <linux/compat.h>
  34 #include <linux/of.h>
  35 #include <linux/of_device.h>
  36
  37 #include <linux/spi/spi.h>
  38 #include <linux/spi/spidev.h>
  39
  40 #include <asm/uaccess.h>
  41
  42
  43 /*
  44  * This supports access to SPI devices using normal userspace I/O calls.
  45  * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
  46  * and often mask message boundaries, full SPI support requires full duplex
  47  * transfers.  There are several kinds of internal message boundaries to
  48  * handle chipselect management and other protocol options.
  49  *
  50  * SPI has a character major number assigned.  We allocate minor numbers
  51  * dynamically using a bitmask.  You must use hotplug tools, such as udev
  52  * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
  53  * nodes, since there is no fixed association of minor numbers with any
  54  * particular SPI bus or device.
  55  */
  56 #define SPIDEV_MAJOR                    153     /* assigned */
  57 #define N_SPI_MINORS                    32      /* ... up to 256 */
  58
  59 static DECLARE_BITMAP(minors, N_SPI_MINORS);
  60
  61
  62 /* Bit masks for spi_device.mode management.  Note that incorrect
  63  * settings for some settings can cause *lots* of trouble for other
  64  * devices on a shared bus:
  65  *
  66  *  - CS_HIGH ... this device will be active when it shouldn't be
  67  *  - 3WIRE ... when active, it won't behave as it should
  68  *  - NO_CS ... there will be no explicit message boundaries; this
  69  *      is completely incompatible with the shared bus model
  70  *  - READY ... transfers may proceed when they shouldn't.
  71  *
  72  * REVISIT should changing those flags be privileged?
  73  */
  74 #define SPI_MODE_MASK           (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
  75                                 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
  76                                 | SPI_NO_CS | SPI_READY)
  77
  78 struct spidev_data {
  79         dev_t                   devt;
  80         spinlock_t              spi_lock;
  81         struct spi_device       *spi;
  82         struct list_head        device_entry;
  83
  84         /* buffer is NULL unless this device is open (users > 0) */
  85         struct mutex            buf_lock;
  86         unsigned                users;
  87         u8                      *buffer;
  88 };
  89
  90 static LIST_HEAD(device_list);
  91 static DEFINE_MUTEX(device_list_lock);
  92
  93 static unsigned bufsiz = 4096;
  94 module_param(bufsiz, uint, S_IRUGO);
  95 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  96
  97 /*-------------------------------------------------------------------------*/
  98
  99 /*
 100  * We can't use the standard synchronous wrappers for file I/O; we
 101  * need to protect against async removal of the underlying spi_device.
 102  */
 103 static void spidev_complete(void *arg)
 104 {
 105         complete(arg);
 106 }
 107
 108 static ssize_t
 109 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 110 {
 111         DECLARE_COMPLETION_ONSTACK(done);
 112         int status;
 113
 114         message->complete = spidev_complete;
 115         message->context = &done;
 116
 117         spin_lock_irq(&spidev->spi_lock);
 118         if (spidev->spi == NULL)
 119                 status = -ESHUTDOWN;
 120         else
 121                 status = spi_async(spidev->spi, message);
 122         spin_unlock_irq(&spidev->spi_lock);
 123
 124         if (status == 0) {
 125                 wait_for_completion(&done);
 126                 status = message->status;
 127                 if (status == 0)
 128                         status = message->actual_length;
 129         }
 130         return status;
 131 }
 132
 133 static inline ssize_t
 134 spidev_sync_write(struct spidev_data *spidev, size_t len)
 135 {
 136         struct spi_transfer     t = {
 137                         .tx_buf         = spidev->buffer,
 138                         .len            = len,
 139                 };
 140         struct spi_message      m;
 141
 142         spi_message_init(&m);
 143         spi_message_add_tail(&t, &m);
 144         return spidev_sync(spidev, &m);
 145 }
 146
 147 static inline ssize_t
 148 spidev_sync_read(struct spidev_data *spidev, size_t len)
 149 {
 150         struct spi_transfer     t = {
 151                         .rx_buf         = spidev->buffer,
 152                         .len            = len,
 153                 };
 154         struct spi_message      m;
 155
 156         spi_message_init(&m);
 157         spi_message_add_tail(&t, &m);
 158         return spidev_sync(spidev, &m);
 159 }
 160
 161 /*-------------------------------------------------------------------------*/
 162
 163 /* Read-only message with current device setup */
 164 static ssize_t
 165 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 166 {
 167         struct spidev_data      *spidev;
 168         ssize_t                 status = 0;
 169
 170         /* chipselect only toggles at start or end of operation */
 171         if (count > bufsiz)
 172                 return -EMSGSIZE;
 173
 174         spidev = filp->private_data;
 175
 176         mutex_lock(&spidev->buf_lock);
 177         status = spidev_sync_read(spidev, count);
 178         if (status > 0) {
 179                 unsigned long   missing;
 180
 181                 missing = copy_to_user(buf, spidev->buffer, status);
 182                 if (missing == status)
 183                         status = -EFAULT;
 184                 else
 185                         status = status - missing;
 186         }
 187         mutex_unlock(&spidev->buf_lock);
 188
 189         return status;
 190 }
 191
 192 /* Write-only message with current device setup */
 193 static ssize_t
 194 spidev_write(struct file *filp, const char __user *buf,
 195                 size_t count, loff_t *f_pos)
 196 {
 197         struct spidev_data      *spidev;
 198         ssize_t                 status = 0;
 199         unsigned long           missing;
 200
 201         /* chipselect only toggles at start or end of operation */
 202         if (count > bufsiz)
 203                 return -EMSGSIZE;
 204
 205         spidev = filp->private_data;
 206
 207         mutex_lock(&spidev->buf_lock);
 208         missing = copy_from_user(spidev->buffer, buf, count);
 209         if (missing == 0) {
 210                 status = spidev_sync_write(spidev, count);
 211         } else
 212                 status = -EFAULT;
 213         mutex_unlock(&spidev->buf_lock);
 214
 215         return status;
 216 }
 217
 218 static int spidev_message(struct spidev_data *spidev,
 219                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 220 {
 221         struct spi_message      msg;
 222         struct spi_transfer     *k_xfers;
 223         struct spi_transfer     *k_tmp;
 224         struct spi_ioc_transfer *u_tmp;
 225         unsigned                n, total;
 226         u8                      *buf;
 227         int                     status = -EFAULT;
 228
 229         spi_message_init(&msg);
 230         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 231         if (k_xfers == NULL)
 232                 return -ENOMEM;
 233
 234         /* Construct spi_message, copying any tx data to bounce buffer.
 235          * We walk the array of user-provided transfers, using each one
 236          * to initialize a kernel version of the same transfer.
 237          */
 238         buf = spidev->buffer;
 239         total = 0;
 240         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 241                         n;
 242                         n--, k_tmp++, u_tmp++) {
 243                 k_tmp->len = u_tmp->len;
 244
 245                 total += k_tmp->len;
 246                 /* Check total length of transfers.  Also check each
 247                  * transfer length to avoid arithmetic overflow.
 248                  */
 249                 if (total > bufsiz || k_tmp->len > bufsiz) {
 250                         status = -EMSGSIZE;
 251                         goto done;
 252                 }
 253
 254                 if (u_tmp->rx_buf) {
 255                         k_tmp->rx_buf = buf;
 256                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
 257                                                 (uintptr_t) u_tmp->rx_buf,
 258                                                 u_tmp->len))
 259                                 goto done;
 260                 }
 261                 if (u_tmp->tx_buf) {
 262                         k_tmp->tx_buf = buf;
 263                         if (copy_from_user(buf, (const u8 __user *)
 264                                                 (uintptr_t) u_tmp->tx_buf,
 265                                         u_tmp->len))
 266                                 goto done;
 267                 }
 268                 buf += k_tmp->len;
 269
 270                 k_tmp->cs_change = !!u_tmp->cs_change;
 271                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 272                 k_tmp->delay_usecs = u_tmp->delay_usecs;
 273                 k_tmp->speed_hz = u_tmp->speed_hz;
 274 #ifdef VERBOSE
 275                 dev_dbg(&spidev->spi->dev,
 276                         "  xfer len %zd %s%s%s%dbits %u usec %uHz\n",
 277                         u_tmp->len,
 278                         u_tmp->rx_buf ? "rx " : "",
 279                         u_tmp->tx_buf ? "tx " : "",
 280                         u_tmp->cs_change ? "cs " : "",
 281                         u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 282                         u_tmp->delay_usecs,
 283                         u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 284 #endif
 285                 spi_message_add_tail(k_tmp, &msg);
 286         }
 287
 288         status = spidev_sync(spidev, &msg);
 289         if (status < 0)
 290                 goto done;
 291
 292         /* copy any rx data out of bounce buffer */
 293         buf = spidev->buffer;
 294         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 295                 if (u_tmp->rx_buf) {
 296                         if (__copy_to_user((u8 __user *)
 297                                         (uintptr_t) u_tmp->rx_buf, buf,
 298                                         u_tmp->len)) {
 299                                 status = -EFAULT;
 300                                 goto done;
 301                         }
 302                 }
 303                 buf += u_tmp->len;
 304         }
 305         status = total;
 306
 307 done:
 308         kfree(k_xfers);
 309         return status;
 310 }
 311
 312 static long
 313 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 314 {
 315         int                     err = 0;
 316         int                     retval = 0;
 317         struct spidev_data      *spidev;
 318         struct spi_device       *spi;
 319         u32                     tmp;
 320         unsigned                n_ioc;
 321         struct spi_ioc_transfer *ioc;
 322
 323         /* Check type and command number */
 324         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 325                 return -ENOTTY;
 326
 327         /* Check access direction once here; don't repeat below.
 328          * IOC_DIR is from the user perspective, while access_ok is
 329          * from the kernel perspective; so they look reversed.
 330          */
 331         if (_IOC_DIR(cmd) & _IOC_READ)
 332                 err = !access_ok(VERIFY_WRITE,
 333                                 (void __user *)arg, _IOC_SIZE(cmd));
 334         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
 335                 err = !access_ok(VERIFY_READ,
 336                                 (void __user *)arg, _IOC_SIZE(cmd));
 337         if (err)
 338                 return -EFAULT;
 339
 340         /* guard against device removal before, or while,
 341          * we issue this ioctl.
 342          */
 343         spidev = filp->private_data;
 344         spin_lock_irq(&spidev->spi_lock);
 345         spi = spi_dev_get(spidev->spi);
 346         spin_unlock_irq(&spidev->spi_lock);
 347
 348         if (spi == NULL)
 349                 return -ESHUTDOWN;
 350
 351         /* use the buffer lock here for triple duty:
 352          *  - prevent I/O (from us) so calling spi_setup() is safe;
 353          *  - prevent concurrent SPI_IOC_WR_* from morphing
 354          *    data fields while SPI_IOC_RD_* reads them;
 355          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 356          */
 357         mutex_lock(&spidev->buf_lock);
 358
 359         switch (cmd) {
 360         /* read requests */
 361         case SPI_IOC_RD_MODE:
 362                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 363                                         (__u8 __user *)arg);
 364                 break;
 365         case SPI_IOC_RD_LSB_FIRST:
 366                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 367                                         (__u8 __user *)arg);
 368                 break;
 369         case SPI_IOC_RD_BITS_PER_WORD:
 370                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
 371                 break;
 372         case SPI_IOC_RD_MAX_SPEED_HZ:
 373                 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
 374                 break;
 375
 376         /* write requests */
 377         case SPI_IOC_WR_MODE:
 378                 retval = __get_user(tmp, (u8 __user *)arg);
 379                 if (retval == 0) {
 380                         u8      save = spi->mode;
 381
 382                         if (tmp & ~SPI_MODE_MASK) {
 383                                 retval = -EINVAL;
 384                                 break;
 385                         }
 386
 387                         tmp |= spi->mode & ~SPI_MODE_MASK;
 388                         spi->mode = (u8)tmp;
 389                         retval = spi_setup(spi);
 390                         if (retval < 0)
 391                                 spi->mode = save;
 392                         else
 393                                 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
 394                 }
 395                 break;
 396         case SPI_IOC_WR_LSB_FIRST:
 397                 retval = __get_user(tmp, (__u8 __user *)arg);
 398                 if (retval == 0) {
 399                         u8      save = spi->mode;
 400
 401                         if (tmp)
 402                                 spi->mode |= SPI_LSB_FIRST;
 403                         else
 404                                 spi->mode &= ~SPI_LSB_FIRST;
 405                         retval = spi_setup(spi);
 406                         if (retval < 0)
 407                                 spi->mode = save;
 408                         else
 409                                 dev_dbg(&spi->dev, "%csb first\n",
 410                                                 tmp ? 'l' : 'm');
 411                 }
 412                 break;
 413         case SPI_IOC_WR_BITS_PER_WORD:
 414                 retval = __get_user(tmp, (__u8 __user *)arg);
 415                 if (retval == 0) {
 416                         u8      save = spi->bits_per_word;
 417
 418                         spi->bits_per_word = tmp;
 419                         retval = spi_setup(spi);
 420                         if (retval < 0)
 421                                 spi->bits_per_word = save;
 422                         else
 423                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 424                 }
 425                 break;
 426         case SPI_IOC_WR_MAX_SPEED_HZ:
 427                 retval = __get_user(tmp, (__u32 __user *)arg);
 428                 if (retval == 0) {
 429                         u32     save = spi->max_speed_hz;
 430
 431                         spi->max_speed_hz = tmp;
 432                         retval = spi_setup(spi);
 433                         if (retval < 0)
 434                                 spi->max_speed_hz = save;
 435                         else
 436                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 437                 }
 438                 break;
 439
 440         default:
 441                 /* segmented and/or full-duplex I/O request */
 442                 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 443                                 || _IOC_DIR(cmd) != _IOC_WRITE) {
 444                         retval = -ENOTTY;
 445                         break;
 446                 }
 447
 448                 tmp = _IOC_SIZE(cmd);
 449                 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
 450                         retval = -EINVAL;
 451                         break;
 452                 }
 453                 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 454                 if (n_ioc == 0)
 455                         break;
 456
 457                 /* copy into scratch area */
 458                 ioc = kmalloc(tmp, GFP_KERNEL);
 459                 if (!ioc) {
 460                         retval = -ENOMEM;
 461                         break;
 462                 }
 463                 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
 464                         kfree(ioc);
 465                         retval = -EFAULT;
 466                         break;
 467                 }
 468
 469                 /* translate to spi_message, execute */
 470                 retval = spidev_message(spidev, ioc, n_ioc);
 471                 kfree(ioc);
 472                 break;
 473         }
 474
 475         mutex_unlock(&spidev->buf_lock);
 476         spi_dev_put(spi);
 477         return retval;
 478 }
 479
 480 #ifdef CONFIG_COMPAT
 481 static long
 482 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 483 {
 484         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 485 }
 486 #else
 487 #define spidev_compat_ioctl NULL
 488 #endif /* CONFIG_COMPAT */
 489
 490 static int spidev_open(struct inode *inode, struct file *filp)
 491 {
 492         struct spidev_data      *spidev;
 493         int                     status = -ENXIO;
 494
 495         mutex_lock(&device_list_lock);
 496
 497         list_for_each_entry(spidev, &device_list, device_entry) {
 498                 if (spidev->devt == inode->i_rdev) {
 499                         status = 0;
 500                         break;
 501                 }
 502         }
 503         if (status == 0) {
 504                 if (!spidev->buffer) {
 505                         spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
 506                         if (!spidev->buffer) {
 507                                 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 508                                 status = -ENOMEM;
 509                         }
 510                 }
 511                 if (status == 0) {
 512                         spidev->users++;
 513                         filp->private_data = spidev;
 514                         nonseekable_open(inode, filp);
 515                 }
 516         } else
 517                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 518
 519         mutex_unlock(&device_list_lock);
 520         return status;
 521 }
 522
 523 static int spidev_release(struct inode *inode, struct file *filp)
 524 {
 525         struct spidev_data      *spidev;
 526         int                     status = 0;
 527
 528         mutex_lock(&device_list_lock);
 529         spidev = filp->private_data;
 530         filp->private_data = NULL;
 531
 532         /* last close? */
 533         spidev->users--;
 534         if (!spidev->users) {
 535                 int             dofree;
 536
 537                 kfree(spidev->buffer);
 538                 spidev->buffer = NULL;
 539
 540                 /* ... after we unbound from the underlying device? */
 541                 spin_lock_irq(&spidev->spi_lock);
 542                 dofree = (spidev->spi == NULL);
 543                 spin_unlock_irq(&spidev->spi_lock);
 544
 545                 if (dofree)
 546                         kfree(spidev);
 547         }
 548         mutex_unlock(&device_list_lock);
 549
 550         return status;
 551 }
 552
 553 static const struct file_operations spidev_fops = {
 554         .owner =        THIS_MODULE,
 555         /* REVISIT switch to aio primitives, so that userspace
 556          * gets more complete API coverage.  It'll simplify things
 557          * too, except for the locking.
 558          */
 559         .write =        spidev_write,
 560         .read =         spidev_read,
 561         .unlocked_ioctl = spidev_ioctl,
 562         .compat_ioctl = spidev_compat_ioctl,
 563         .open =         spidev_open,
 564         .release =      spidev_release,
 565         .llseek =       no_llseek,
 566 };
 567
 568 /*-------------------------------------------------------------------------*/
 569
 570 /* The main reason to have this class is to make mdev/udev create the
 571  * /dev/spidevB.C character device nodes exposing our userspace API.
 572  * It also simplifies memory management.
 573  */
 574
 575 static struct class *spidev_class;
 576
 577 /*-------------------------------------------------------------------------*/
 578
 579 static int spidev_probe(struct spi_device *spi)
 580 {
 581         struct spidev_data      *spidev;
 582         int                     status;
 583         unsigned long           minor;
 584
 585         /* Allocate driver data */
 586         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 587         if (!spidev)
 588                 return -ENOMEM;
 589
 590         /* Initialize the driver data */
 591         spidev->spi = spi;
 592         spin_lock_init(&spidev->spi_lock);
 593         mutex_init(&spidev->buf_lock);
 594
 595         INIT_LIST_HEAD(&spidev->device_entry);
 596
 597         /* If we can allocate a minor number, hook up this device.
 598          * Reusing minors is fine so long as udev or mdev is working.
 599          */
 600         mutex_lock(&device_list_lock);
 601         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 602         if (minor < N_SPI_MINORS) {
 603                 struct device *dev;
 604
 605                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 606                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 607                                     spidev, "spidev%d.%d",
 608                                     spi->master->bus_num, spi->chip_select);
 609                 status = PTR_RET(dev);
 610         } else {
 611                 dev_dbg(&spi->dev, "no minor number available!\n");
 612                 status = -ENODEV;
 613         }
 614         if (status == 0) {
 615                 set_bit(minor, minors);
 616                 list_add(&spidev->device_entry, &device_list);
 617         }
 618         mutex_unlock(&device_list_lock);
 619
 620         if (status == 0)
 621                 spi_set_drvdata(spi, spidev);
 622         else
 623                 kfree(spidev);
 624
 625         return status;
 626 }
 627
 628 static int spidev_remove(struct spi_device *spi)
 629 {
 630         struct spidev_data      *spidev = spi_get_drvdata(spi);
 631
 632         /* make sure ops on existing fds can abort cleanly */
 633         spin_lock_irq(&spidev->spi_lock);
 634         spidev->spi = NULL;
 635         spi_set_drvdata(spi, NULL);
 636         spin_unlock_irq(&spidev->spi_lock);
 637
 638         /* prevent new opens */
 639         mutex_lock(&device_list_lock);
 640         list_del(&spidev->device_entry);
 641         device_destroy(spidev_class, spidev->devt);
 642         clear_bit(MINOR(spidev->devt), minors);
 643         if (spidev->users == 0)
 644                 kfree(spidev);
 645         mutex_unlock(&device_list_lock);
 646
 647         return 0;
 648 }
 649
 650 static const struct of_device_id spidev_dt_ids[] = {
 651         { .compatible = "rohm,dh2228fv" },
 652         {},
 653 };
 654
 655 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 656
 657 static struct spi_driver spidev_spi_driver = {
 658         .driver = {
 659                 .name =         "spidev",
 660                 .owner =        THIS_MODULE,
 661                 .of_match_table = of_match_ptr(spidev_dt_ids),
 662         },
 663         .probe =        spidev_probe,
 664         .remove =       spidev_remove,
 665
 666         /* NOTE:  suspend/resume methods are not necessary here.
 667          * We don't do anything except pass the requests to/from
 668          * the underlying controller.  The refrigerator handles
 669          * most issues; the controller driver handles the rest.
 670          */
 671 };
 672
 673 /*-------------------------------------------------------------------------*/
 674
 675 static int __init spidev_init(void)
 676 {
 677         int status;
 678
 679         /* Claim our 256 reserved device numbers.  Then register a class
 680          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 681          * the driver which manages those device numbers.
 682          */
 683         BUILD_BUG_ON(N_SPI_MINORS > 256);
 684         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 685         if (status < 0)
 686                 return status;
 687
 688         spidev_class = class_create(THIS_MODULE, "spidev");
 689         if (IS_ERR(spidev_class)) {
 690                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 691                 return PTR_ERR(spidev_class);
 692         }
 693
 694         status = spi_register_driver(&spidev_spi_driver);
 695         if (status < 0) {
 696                 class_destroy(spidev_class);
 697                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 698         }
 699         return status;
 700 }
 701 module_init(spidev_init);
 702
 703 static void __exit spidev_exit(void)
 704 {
 705         spi_unregister_driver(&spidev_spi_driver);
 706         class_destroy(spidev_class);
 707         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 708 }
 709 module_exit(spidev_exit);
 710
 711 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 712 MODULE_DESCRIPTION("User mode SPI device interface");
 713 MODULE_LICENSE("GPL");
 714 MODULE_ALIAS("spi:spidev");