drivers/spi/spidev.c

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