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 <linux/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 | SPI_TX_DUAL \
  77                                 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
  78
  79 struct spidev_data {
  80         dev_t                   devt;
  81         spinlock_t              spi_lock;
  82         struct spi_device       *spi;
  83         struct list_head        device_entry;
  84
  85         /* buffer is NULL unless this device is open (users > 0) */
  86         struct mutex            buf_lock;
  87         unsigned                users;
  88         u8                      *buffer;
  89 };
  90
  91 static LIST_HEAD(device_list);
  92 static DEFINE_MUTEX(device_list_lock);
  93
  94 static unsigned bufsiz = 4096;
  95 module_param(bufsiz, uint, S_IRUGO);
  96 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  97
  98 /*-------------------------------------------------------------------------*/
  99
 100 /*
 101  * We can't use the standard synchronous wrappers for file I/O; we
 102  * need to protect against async removal of the underlying spi_device.
 103  */
 104 static void spidev_complete(void *arg)
 105 {
 106         complete(arg);
 107 }
 108
 109 static ssize_t
 110 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 111 {
 112         DECLARE_COMPLETION_ONSTACK(done);
 113         int status;
 114
 115         message->complete = spidev_complete;
 116         message->context = &done;
 117
 118         spin_lock_irq(&spidev->spi_lock);
 119         if (spidev->spi == NULL)
 120                 status = -ESHUTDOWN;
 121         else
 122                 status = spi_async(spidev->spi, message);
 123         spin_unlock_irq(&spidev->spi_lock);
 124
 125         if (status == 0) {
 126                 wait_for_completion(&done);
 127                 status = message->status;
 128                 if (status == 0)
 129                         status = message->actual_length;
 130         }
 131         return status;
 132 }
 133
 134 static inline ssize_t
 135 spidev_sync_write(struct spidev_data *spidev, size_t len)
 136 {
 137         struct spi_transfer     t = {
 138                         .tx_buf         = spidev->buffer,
 139                         .len            = len,
 140                 };
 141         struct spi_message      m;
 142
 143         spi_message_init(&m);
 144         spi_message_add_tail(&t, &m);
 145         return spidev_sync(spidev, &m);
 146 }
 147
 148 static inline ssize_t
 149 spidev_sync_read(struct spidev_data *spidev, size_t len)
 150 {
 151         struct spi_transfer     t = {
 152                         .rx_buf         = spidev->buffer,
 153                         .len            = len,
 154                 };
 155         struct spi_message      m;
 156
 157         spi_message_init(&m);
 158         spi_message_add_tail(&t, &m);
 159         return spidev_sync(spidev, &m);
 160 }
 161
 162 /*-------------------------------------------------------------------------*/
 163
 164 /* Read-only message with current device setup */
 165 static ssize_t
 166 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 167 {
 168         struct spidev_data      *spidev;
 169         ssize_t                 status = 0;
 170
 171         /* chipselect only toggles at start or end of operation */
 172         if (count > bufsiz)
 173                 return -EMSGSIZE;
 174
 175         spidev = filp->private_data;
 176
 177         mutex_lock(&spidev->buf_lock);
 178         status = spidev_sync_read(spidev, count);
 179         if (status > 0) {
 180                 unsigned long   missing;
 181
 182                 missing = copy_to_user(buf, spidev->buffer, status);
 183                 if (missing == status)
 184                         status = -EFAULT;
 185                 else
 186                         status = status - missing;
 187         }
 188         mutex_unlock(&spidev->buf_lock);
 189
 190         return status;
 191 }
 192
 193 /* Write-only message with current device setup */
 194 static ssize_t
 195 spidev_write(struct file *filp, const char __user *buf,
 196                 size_t count, loff_t *f_pos)
 197 {
 198         struct spidev_data      *spidev;
 199         ssize_t                 status = 0;
 200         unsigned long           missing;
 201
 202         /* chipselect only toggles at start or end of operation */
 203         if (count > bufsiz)
 204                 return -EMSGSIZE;
 205
 206         spidev = filp->private_data;
 207
 208         mutex_lock(&spidev->buf_lock);
 209         missing = copy_from_user(spidev->buffer, buf, count);
 210         if (missing == 0)
 211                 status = spidev_sync_write(spidev, count);
 212         else
 213                 status = -EFAULT;
 214         mutex_unlock(&spidev->buf_lock);
 215
 216         return status;
 217 }
 218
 219 static int spidev_message(struct spidev_data *spidev,
 220                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 221 {
 222         struct spi_message      msg;
 223         struct spi_transfer     *k_xfers;
 224         struct spi_transfer     *k_tmp;
 225         struct spi_ioc_transfer *u_tmp;
 226         unsigned                n, total;
 227         u8                      *buf;
 228         int                     status = -EFAULT;
 229
 230         spi_message_init(&msg);
 231         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 232         if (k_xfers == NULL)
 233                 return -ENOMEM;
 234
 235         /* Construct spi_message, copying any tx data to bounce buffer.
 236          * We walk the array of user-provided transfers, using each one
 237          * to initialize a kernel version of the same transfer.
 238          */
 239         buf = spidev->buffer;
 240         total = 0;
 241         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 242                         n;
 243                         n--, k_tmp++, u_tmp++) {
 244                 k_tmp->len = u_tmp->len;
 245
 246                 total += k_tmp->len;
 247                 if (total > bufsiz) {
 248                         status = -EMSGSIZE;
 249                         goto done;
 250                 }
 251
 252                 if (u_tmp->rx_buf) {
 253                         k_tmp->rx_buf = buf;
 254                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
 255                                                 (uintptr_t) u_tmp->rx_buf,
 256                                                 u_tmp->len))
 257                                 goto done;
 258                 }
 259                 if (u_tmp->tx_buf) {
 260                         k_tmp->tx_buf = buf;
 261                         if (copy_from_user(buf, (const u8 __user *)
 262                                                 (uintptr_t) u_tmp->tx_buf,
 263                                         u_tmp->len))
 264                                 goto done;
 265                 }
 266                 buf += k_tmp->len;
 267
 268                 k_tmp->cs_change = !!u_tmp->cs_change;
 269                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 270                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 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_MODE32:
 366                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 367                                         (__u32 __user *)arg);
 368                 break;
 369         case SPI_IOC_RD_LSB_FIRST:
 370                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 371                                         (__u8 __user *)arg);
 372                 break;
 373         case SPI_IOC_RD_BITS_PER_WORD:
 374                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
 375                 break;
 376         case SPI_IOC_RD_MAX_SPEED_HZ:
 377                 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
 378                 break;
 379
 380         /* write requests */
 381         case SPI_IOC_WR_MODE:
 382         case SPI_IOC_WR_MODE32:
 383                 if (cmd == SPI_IOC_WR_MODE)
 384                         retval = __get_user(tmp, (u8 __user *)arg);
 385                 else
 386                         retval = __get_user(tmp, (u32 __user *)arg);
 387                 if (retval == 0) {
 388                         u32     save = spi->mode;
 389
 390                         if (tmp & ~SPI_MODE_MASK) {
 391                                 retval = -EINVAL;
 392                                 break;
 393                         }
 394
 395                         tmp |= spi->mode & ~SPI_MODE_MASK;
 396                         spi->mode = (u16)tmp;
 397                         retval = spi_setup(spi);
 398                         if (retval < 0)
 399                                 spi->mode = save;
 400                         else
 401                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 402                 }
 403                 break;
 404         case SPI_IOC_WR_LSB_FIRST:
 405                 retval = __get_user(tmp, (__u8 __user *)arg);
 406                 if (retval == 0) {
 407                         u32     save = spi->mode;
 408
 409                         if (tmp)
 410                                 spi->mode |= SPI_LSB_FIRST;
 411                         else
 412                                 spi->mode &= ~SPI_LSB_FIRST;
 413                         retval = spi_setup(spi);
 414                         if (retval < 0)
 415                                 spi->mode = save;
 416                         else
 417                                 dev_dbg(&spi->dev, "%csb first\n",
 418                                                 tmp ? 'l' : 'm');
 419                 }
 420                 break;
 421         case SPI_IOC_WR_BITS_PER_WORD:
 422                 retval = __get_user(tmp, (__u8 __user *)arg);
 423                 if (retval == 0) {
 424                         u8      save = spi->bits_per_word;
 425
 426                         spi->bits_per_word = tmp;
 427                         retval = spi_setup(spi);
 428                         if (retval < 0)
 429                                 spi->bits_per_word = save;
 430                         else
 431                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 432                 }
 433                 break;
 434         case SPI_IOC_WR_MAX_SPEED_HZ:
 435                 retval = __get_user(tmp, (__u32 __user *)arg);
 436                 if (retval == 0) {
 437                         u32     save = spi->max_speed_hz;
 438
 439                         spi->max_speed_hz = tmp;
 440                         retval = spi_setup(spi);
 441                         if (retval < 0)
 442                                 spi->max_speed_hz = save;
 443                         else
 444                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 445                 }
 446                 break;
 447
 448         default:
 449                 /* segmented and/or full-duplex I/O request */
 450                 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 451                                 || _IOC_DIR(cmd) != _IOC_WRITE) {
 452                         retval = -ENOTTY;
 453                         break;
 454                 }
 455
 456                 tmp = _IOC_SIZE(cmd);
 457                 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
 458                         retval = -EINVAL;
 459                         break;
 460                 }
 461                 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 462                 if (n_ioc == 0)
 463                         break;
 464
 465                 /* copy into scratch area */
 466                 ioc = kmalloc(tmp, GFP_KERNEL);
 467                 if (!ioc) {
 468                         retval = -ENOMEM;
 469                         break;
 470                 }
 471                 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
 472                         kfree(ioc);
 473                         retval = -EFAULT;
 474                         break;
 475                 }
 476
 477                 /* translate to spi_message, execute */
 478                 retval = spidev_message(spidev, ioc, n_ioc);
 479                 kfree(ioc);
 480                 break;
 481         }
 482
 483         mutex_unlock(&spidev->buf_lock);
 484         spi_dev_put(spi);
 485         return retval;
 486 }
 487
 488 #ifdef CONFIG_COMPAT
 489 static long
 490 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 491 {
 492         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 493 }
 494 #else
 495 #define spidev_compat_ioctl NULL
 496 #endif /* CONFIG_COMPAT */
 497
 498 static int spidev_open(struct inode *inode, struct file *filp)
 499 {
 500         struct spidev_data      *spidev;
 501         int                     status = -ENXIO;
 502
 503         mutex_lock(&device_list_lock);
 504
 505         list_for_each_entry(spidev, &device_list, device_entry) {
 506                 if (spidev->devt == inode->i_rdev) {
 507                         status = 0;
 508                         break;
 509                 }
 510         }
 511         if (status == 0) {
 512                 if (!spidev->buffer) {
 513                         spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
 514                         if (!spidev->buffer) {
 515                                 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 516                                 status = -ENOMEM;
 517                         }
 518                 }
 519                 if (status == 0) {
 520                         spidev->users++;
 521                         filp->private_data = spidev;
 522                         nonseekable_open(inode, filp);
 523                 }
 524         } else
 525                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 526
 527         mutex_unlock(&device_list_lock);
 528         return status;
 529 }
 530
 531 static int spidev_release(struct inode *inode, struct file *filp)
 532 {
 533         struct spidev_data      *spidev;
 534         int                     status = 0;
 535
 536         mutex_lock(&device_list_lock);
 537         spidev = filp->private_data;
 538         filp->private_data = NULL;
 539
 540         /* last close? */
 541         spidev->users--;
 542         if (!spidev->users) {
 543                 int             dofree;
 544
 545                 kfree(spidev->buffer);
 546                 spidev->buffer = NULL;
 547
 548                 /* ... after we unbound from the underlying device? */
 549                 spin_lock_irq(&spidev->spi_lock);
 550                 dofree = (spidev->spi == NULL);
 551                 spin_unlock_irq(&spidev->spi_lock);
 552
 553                 if (dofree)
 554                         kfree(spidev);
 555         }
 556         mutex_unlock(&device_list_lock);
 557
 558         return status;
 559 }
 560
 561 static const struct file_operations spidev_fops = {
 562         .owner =        THIS_MODULE,
 563         /* REVISIT switch to aio primitives, so that userspace
 564          * gets more complete API coverage.  It'll simplify things
 565          * too, except for the locking.
 566          */
 567         .write =        spidev_write,
 568         .read =         spidev_read,
 569         .unlocked_ioctl = spidev_ioctl,
 570         .compat_ioctl = spidev_compat_ioctl,
 571         .open =         spidev_open,
 572         .release =      spidev_release,
 573         .llseek =       no_llseek,
 574 };
 575
 576 /*-------------------------------------------------------------------------*/
 577
 578 /* The main reason to have this class is to make mdev/udev create the
 579  * /dev/spidevB.C character device nodes exposing our userspace API.
 580  * It also simplifies memory management.
 581  */
 582
 583 static struct class *spidev_class;
 584
 585 /*-------------------------------------------------------------------------*/
 586
 587 static int spidev_probe(struct spi_device *spi)
 588 {
 589         struct spidev_data      *spidev;
 590         int                     status;
 591         unsigned long           minor;
 592
 593         /* Allocate driver data */
 594         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 595         if (!spidev)
 596                 return -ENOMEM;
 597
 598         /* Initialize the driver data */
 599         spidev->spi = spi;
 600         spin_lock_init(&spidev->spi_lock);
 601         mutex_init(&spidev->buf_lock);
 602
 603         INIT_LIST_HEAD(&spidev->device_entry);
 604
 605         /* If we can allocate a minor number, hook up this device.
 606          * Reusing minors is fine so long as udev or mdev is working.
 607          */
 608         mutex_lock(&device_list_lock);
 609         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 610         if (minor < N_SPI_MINORS) {
 611                 struct device *dev;
 612
 613                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 614                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 615                                     spidev, "spidev%d.%d",
 616                                     spi->master->bus_num, spi->chip_select);
 617                 status = PTR_ERR_OR_ZERO(dev);
 618         } else {
 619                 dev_dbg(&spi->dev, "no minor number available!\n");
 620                 status = -ENODEV;
 621         }
 622         if (status == 0) {
 623                 set_bit(minor, minors);
 624                 list_add(&spidev->device_entry, &device_list);
 625         }
 626         mutex_unlock(&device_list_lock);
 627
 628         if (status == 0)
 629                 spi_set_drvdata(spi, spidev);
 630         else
 631                 kfree(spidev);
 632
 633         return status;
 634 }
 635
 636 static int spidev_remove(struct spi_device *spi)
 637 {
 638         struct spidev_data      *spidev = spi_get_drvdata(spi);
 639
 640         /* make sure ops on existing fds can abort cleanly */
 641         spin_lock_irq(&spidev->spi_lock);
 642         spidev->spi = NULL;
 643         spin_unlock_irq(&spidev->spi_lock);
 644
 645         /* prevent new opens */
 646         mutex_lock(&device_list_lock);
 647         list_del(&spidev->device_entry);
 648         device_destroy(spidev_class, spidev->devt);
 649         clear_bit(MINOR(spidev->devt), minors);
 650         if (spidev->users == 0)
 651                 kfree(spidev);
 652         mutex_unlock(&device_list_lock);
 653
 654         return 0;
 655 }
 656
 657 static const struct of_device_id spidev_dt_ids[] = {
 658         { .compatible = "rohm,dh2228fv" },
 659         {},
 660 };
 661
 662 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 663
 664 static struct spi_driver spidev_spi_driver = {
 665         .driver = {
 666                 .name =         "spidev",
 667                 .owner =        THIS_MODULE,
 668                 .of_match_table = of_match_ptr(spidev_dt_ids),
 669         },
 670         .probe =        spidev_probe,
 671         .remove =       spidev_remove,
 672
 673         /* NOTE:  suspend/resume methods are not necessary here.
 674          * We don't do anything except pass the requests to/from
 675          * the underlying controller.  The refrigerator handles
 676          * most issues; the controller driver handles the rest.
 677          */
 678 };
 679
 680 /*-------------------------------------------------------------------------*/
 681
 682 static int __init spidev_init(void)
 683 {
 684         int status;
 685
 686         /* Claim our 256 reserved device numbers.  Then register a class
 687          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 688          * the driver which manages those device numbers.
 689          */
 690         BUILD_BUG_ON(N_SPI_MINORS > 256);
 691         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 692         if (status < 0)
 693                 return status;
 694
 695         spidev_class = class_create(THIS_MODULE, "spidev");
 696         if (IS_ERR(spidev_class)) {
 697                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 698                 return PTR_ERR(spidev_class);
 699         }
 700
 701         status = spi_register_driver(&spidev_spi_driver);
 702         if (status < 0) {
 703                 class_destroy(spidev_class);
 704                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 705         }
 706         return status;
 707 }
 708 module_init(spidev_init);
 709
 710 static void __exit spidev_exit(void)
 711 {
 712         spi_unregister_driver(&spidev_spi_driver);
 713         class_destroy(spidev_class);
 714         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 715 }
 716 module_exit(spidev_exit);
 717
 718 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 719 MODULE_DESCRIPTION("User mode SPI device interface");
 720 MODULE_LICENSE("GPL");
 721 MODULE_ALIAS("spi:spidev");