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, status);
 174                 if (missing == status)
 175                         status = -EFAULT;
 176                 else
 177                         status = status - 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         } else
 204                 status = -EFAULT;
 205         mutex_unlock(&spidev->buf_lock);
 206
 207         return status;
 208 }
 209
 210 static int spidev_message(struct spidev_data *spidev,
 211                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 212 {
 213         struct spi_message      msg;
 214         struct spi_transfer     *k_xfers;
 215         struct spi_transfer     *k_tmp;
 216         struct spi_ioc_transfer *u_tmp;
 217         unsigned                n, total;
 218         u8                      *buf;
 219         int                     status = -EFAULT;
 220
 221         spi_message_init(&msg);
 222         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 223         if (k_xfers == NULL)
 224                 return -ENOMEM;
 225
 226         /* Construct spi_message, copying any tx data to bounce buffer.
 227          * We walk the array of user-provided transfers, using each one
 228          * to initialize a kernel version of the same transfer.
 229          */
 230         mutex_lock(&spidev->buf_lock);
 231         buf = spidev->buffer;
 232         total = 0;
 233         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 234                         n;
 235                         n--, k_tmp++, u_tmp++) {
 236                 k_tmp->len = u_tmp->len;
 237
 238                 total += k_tmp->len;
 239                 if (total > bufsiz) {
 240                         status = -EMSGSIZE;
 241                         goto done;
 242                 }
 243
 244                 if (u_tmp->rx_buf) {
 245                         k_tmp->rx_buf = buf;
 246                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
 247                                                 (uintptr_t) u_tmp->rx_buf,
 248                                                 u_tmp->len))
 249                                 goto done;
 250                 }
 251                 if (u_tmp->tx_buf) {
 252                         k_tmp->tx_buf = buf;
 253                         if (copy_from_user(buf, (const u8 __user *)
 254                                                 (uintptr_t) u_tmp->tx_buf,
 255                                         u_tmp->len))
 256                                 goto done;
 257                 }
 258                 buf += k_tmp->len;
 259
 260                 k_tmp->cs_change = !!u_tmp->cs_change;
 261                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 262                 k_tmp->delay_usecs = u_tmp->delay_usecs;
 263                 k_tmp->speed_hz = u_tmp->speed_hz;
 264 #ifdef VERBOSE
 265                 dev_dbg(&spi->dev,
 266                         "  xfer len %zd %s%s%s%dbits %u usec %uHz\n",
 267                         u_tmp->len,
 268                         u_tmp->rx_buf ? "rx " : "",
 269                         u_tmp->tx_buf ? "tx " : "",
 270                         u_tmp->cs_change ? "cs " : "",
 271                         u_tmp->bits_per_word ? : spi->bits_per_word,
 272                         u_tmp->delay_usecs,
 273                         u_tmp->speed_hz ? : spi->max_speed_hz);
 274 #endif
 275                 spi_message_add_tail(k_tmp, &msg);
 276         }
 277
 278         status = spidev_sync(spidev, &msg);
 279         if (status < 0)
 280                 goto done;
 281
 282         /* copy any rx data out of bounce buffer */
 283         buf = spidev->buffer;
 284         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 285                 if (u_tmp->rx_buf) {
 286                         if (__copy_to_user((u8 __user *)
 287                                         (uintptr_t) u_tmp->rx_buf, buf,
 288                                         u_tmp->len)) {
 289                                 status = -EFAULT;
 290                                 goto done;
 291                         }
 292                 }
 293                 buf += u_tmp->len;
 294         }
 295         status = total;
 296
 297 done:
 298         mutex_unlock(&spidev->buf_lock);
 299         kfree(k_xfers);
 300         return status;
 301 }
 302
 303 static int
 304 spidev_ioctl(struct inode *inode, struct file *filp,
 305                 unsigned int cmd, unsigned long arg)
 306 {
 307         int                     err = 0;
 308         int                     retval = 0;
 309         struct spidev_data      *spidev;
 310         struct spi_device       *spi;
 311         u32                     tmp;
 312         unsigned                n_ioc;
 313         struct spi_ioc_transfer *ioc;
 314
 315         /* Check type and command number */
 316         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 317                 return -ENOTTY;
 318
 319         /* Check access direction once here; don't repeat below.
 320          * IOC_DIR is from the user perspective, while access_ok is
 321          * from the kernel perspective; so they look reversed.
 322          */
 323         if (_IOC_DIR(cmd) & _IOC_READ)
 324                 err = !access_ok(VERIFY_WRITE,
 325                                 (void __user *)arg, _IOC_SIZE(cmd));
 326         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
 327                 err = !access_ok(VERIFY_READ,
 328                                 (void __user *)arg, _IOC_SIZE(cmd));
 329         if (err)
 330                 return -EFAULT;
 331
 332         /* guard against device removal before, or while,
 333          * we issue this ioctl.
 334          */
 335         spidev = filp->private_data;
 336         spin_lock_irq(&spidev->spi_lock);
 337         spi = spi_dev_get(spidev->spi);
 338         spin_unlock_irq(&spidev->spi_lock);
 339
 340         if (spi == NULL)
 341                 return -ESHUTDOWN;
 342
 343         switch (cmd) {
 344         /* read requests */
 345         case SPI_IOC_RD_MODE:
 346                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 347                                         (__u8 __user *)arg);
 348                 break;
 349         case SPI_IOC_RD_LSB_FIRST:
 350                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 351                                         (__u8 __user *)arg);
 352                 break;
 353         case SPI_IOC_RD_BITS_PER_WORD:
 354                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
 355                 break;
 356         case SPI_IOC_RD_MAX_SPEED_HZ:
 357                 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
 358                 break;
 359
 360         /* write requests */
 361         case SPI_IOC_WR_MODE:
 362                 retval = __get_user(tmp, (u8 __user *)arg);
 363                 if (retval == 0) {
 364                         u8      save = spi->mode;
 365
 366                         if (tmp & ~SPI_MODE_MASK) {
 367                                 retval = -EINVAL;
 368                                 break;
 369                         }
 370
 371                         tmp |= spi->mode & ~SPI_MODE_MASK;
 372                         spi->mode = (u8)tmp;
 373                         retval = spi_setup(spi);
 374                         if (retval < 0)
 375                                 spi->mode = save;
 376                         else
 377                                 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
 378                 }
 379                 break;
 380         case SPI_IOC_WR_LSB_FIRST:
 381                 retval = __get_user(tmp, (__u8 __user *)arg);
 382                 if (retval == 0) {
 383                         u8      save = spi->mode;
 384
 385                         if (tmp)
 386                                 spi->mode |= SPI_LSB_FIRST;
 387                         else
 388                                 spi->mode &= ~SPI_LSB_FIRST;
 389                         retval = spi_setup(spi);
 390                         if (retval < 0)
 391                                 spi->mode = save;
 392                         else
 393                                 dev_dbg(&spi->dev, "%csb first\n",
 394                                                 tmp ? 'l' : 'm');
 395                 }
 396                 break;
 397         case SPI_IOC_WR_BITS_PER_WORD:
 398                 retval = __get_user(tmp, (__u8 __user *)arg);
 399                 if (retval == 0) {
 400                         u8      save = spi->bits_per_word;
 401
 402                         spi->bits_per_word = tmp;
 403                         retval = spi_setup(spi);
 404                         if (retval < 0)
 405                                 spi->bits_per_word = save;
 406                         else
 407                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 408                 }
 409                 break;
 410         case SPI_IOC_WR_MAX_SPEED_HZ:
 411                 retval = __get_user(tmp, (__u32 __user *)arg);
 412                 if (retval == 0) {
 413                         u32     save = spi->max_speed_hz;
 414
 415                         spi->max_speed_hz = tmp;
 416                         retval = spi_setup(spi);
 417                         if (retval < 0)
 418                                 spi->max_speed_hz = save;
 419                         else
 420                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 421                 }
 422                 break;
 423
 424         default:
 425                 /* segmented and/or full-duplex I/O request */
 426                 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 427                                 || _IOC_DIR(cmd) != _IOC_WRITE) {
 428                         retval = -ENOTTY;
 429                         break;
 430                 }
 431
 432                 tmp = _IOC_SIZE(cmd);
 433                 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
 434                         retval = -EINVAL;
 435                         break;
 436                 }
 437                 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 438                 if (n_ioc == 0)
 439                         break;
 440
 441                 /* copy into scratch area */
 442                 ioc = kmalloc(tmp, GFP_KERNEL);
 443                 if (!ioc) {
 444                         retval = -ENOMEM;
 445                         break;
 446                 }
 447                 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
 448                         kfree(ioc);
 449                         retval = -EFAULT;
 450                         break;
 451                 }
 452
 453                 /* translate to spi_message, execute */
 454                 retval = spidev_message(spidev, ioc, n_ioc);
 455                 kfree(ioc);
 456                 break;
 457         }
 458         spi_dev_put(spi);
 459         return retval;
 460 }
 461
 462 static int spidev_open(struct inode *inode, struct file *filp)
 463 {
 464         struct spidev_data      *spidev;
 465         int                     status = -ENXIO;
 466
 467         mutex_lock(&device_list_lock);
 468
 469         list_for_each_entry(spidev, &device_list, device_entry) {
 470                 if (spidev->devt == inode->i_rdev) {
 471                         status = 0;
 472                         break;
 473                 }
 474         }
 475         if (status == 0) {
 476                 if (!spidev->buffer) {
 477                         spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
 478                         if (!spidev->buffer) {
 479                                 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 480                                 status = -ENOMEM;
 481                         }
 482                 }
 483                 if (status == 0) {
 484                         spidev->users++;
 485                         filp->private_data = spidev;
 486                         nonseekable_open(inode, filp);
 487                 }
 488         } else
 489                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 490
 491         mutex_unlock(&device_list_lock);
 492         return status;
 493 }
 494
 495 static int spidev_release(struct inode *inode, struct file *filp)
 496 {
 497         struct spidev_data      *spidev;
 498         int                     status = 0;
 499
 500         mutex_lock(&device_list_lock);
 501         spidev = filp->private_data;
 502         filp->private_data = NULL;
 503
 504         /* last close? */
 505         spidev->users--;
 506         if (!spidev->users) {
 507                 int             dofree;
 508
 509                 kfree(spidev->buffer);
 510                 spidev->buffer = NULL;
 511
 512                 /* ... after we unbound from the underlying device? */
 513                 spin_lock_irq(&spidev->spi_lock);
 514                 dofree = (spidev->spi == NULL);
 515                 spin_unlock_irq(&spidev->spi_lock);
 516
 517                 if (dofree)
 518                         kfree(spidev);
 519         }
 520         mutex_unlock(&device_list_lock);
 521
 522         return status;
 523 }
 524
 525 static struct file_operations spidev_fops = {
 526         .owner =        THIS_MODULE,
 527         /* REVISIT switch to aio primitives, so that userspace
 528          * gets more complete API coverage.  It'll simplify things
 529          * too, except for the locking.
 530          */
 531         .write =        spidev_write,
 532         .read =         spidev_read,
 533         .ioctl =        spidev_ioctl,
 534         .open =         spidev_open,
 535         .release =      spidev_release,
 536 };
 537
 538 /*-------------------------------------------------------------------------*/
 539
 540 /* The main reason to have this class is to make mdev/udev create the
 541  * /dev/spidevB.C character device nodes exposing our userspace API.
 542  * It also simplifies memory management.
 543  */
 544
 545 static struct class *spidev_class;
 546
 547 /*-------------------------------------------------------------------------*/
 548
 549 static int spidev_probe(struct spi_device *spi)
 550 {
 551         struct spidev_data      *spidev;
 552         int                     status;
 553         unsigned long           minor;
 554
 555         /* Allocate driver data */
 556         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 557         if (!spidev)
 558                 return -ENOMEM;
 559
 560         /* Initialize the driver data */
 561         spidev->spi = spi;
 562         spin_lock_init(&spidev->spi_lock);
 563         mutex_init(&spidev->buf_lock);
 564
 565         INIT_LIST_HEAD(&spidev->device_entry);
 566
 567         /* If we can allocate a minor number, hook up this device.
 568          * Reusing minors is fine so long as udev or mdev is working.
 569          */
 570         mutex_lock(&device_list_lock);
 571         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 572         if (minor < N_SPI_MINORS) {
 573                 struct device *dev;
 574
 575                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 576                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 577                                 "spidev%d.%d",
 578                                 spi->master->bus_num, spi->chip_select);
 579                 status = IS_ERR(dev) ? PTR_ERR(dev) : 0;
 580         } else {
 581                 dev_dbg(&spi->dev, "no minor number available!\n");
 582                 status = -ENODEV;
 583         }
 584         if (status == 0) {
 585                 set_bit(minor, minors);
 586                 spi_set_drvdata(spi, spidev);
 587                 list_add(&spidev->device_entry, &device_list);
 588         }
 589         mutex_unlock(&device_list_lock);
 590
 591         if (status != 0)
 592                 kfree(spidev);
 593
 594         return status;
 595 }
 596
 597 static int spidev_remove(struct spi_device *spi)
 598 {
 599         struct spidev_data      *spidev = spi_get_drvdata(spi);
 600
 601         /* make sure ops on existing fds can abort cleanly */
 602         spin_lock_irq(&spidev->spi_lock);
 603         spidev->spi = NULL;
 604         spi_set_drvdata(spi, NULL);
 605         spin_unlock_irq(&spidev->spi_lock);
 606
 607         /* prevent new opens */
 608         mutex_lock(&device_list_lock);
 609         list_del(&spidev->device_entry);
 610         device_destroy(spidev_class, spidev->devt);
 611         clear_bit(MINOR(spidev->devt), minors);
 612         if (spidev->users == 0)
 613                 kfree(spidev);
 614         mutex_unlock(&device_list_lock);
 615
 616         return 0;
 617 }
 618
 619 static struct spi_driver spidev_spi = {
 620         .driver = {
 621                 .name =         "spidev",
 622                 .owner =        THIS_MODULE,
 623         },
 624         .probe =        spidev_probe,
 625         .remove =       __devexit_p(spidev_remove),
 626
 627         /* NOTE:  suspend/resume methods are not necessary here.
 628          * We don't do anything except pass the requests to/from
 629          * the underlying controller.  The refrigerator handles
 630          * most issues; the controller driver handles the rest.
 631          */
 632 };
 633
 634 /*-------------------------------------------------------------------------*/
 635
 636 static int __init spidev_init(void)
 637 {
 638         int status;
 639
 640         /* Claim our 256 reserved device numbers.  Then register a class
 641          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 642          * the driver which manages those device numbers.
 643          */
 644         BUILD_BUG_ON(N_SPI_MINORS > 256);
 645         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 646         if (status < 0)
 647                 return status;
 648
 649         spidev_class = class_create(THIS_MODULE, "spidev");
 650         if (IS_ERR(spidev_class)) {
 651                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
 652                 return PTR_ERR(spidev_class);
 653         }
 654
 655         status = spi_register_driver(&spidev_spi);
 656         if (status < 0) {
 657                 class_destroy(spidev_class);
 658                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
 659         }
 660         return status;
 661 }
 662 module_init(spidev_init);
 663
 664 static void __exit spidev_exit(void)
 665 {
 666         spi_unregister_driver(&spidev_spi);
 667         class_destroy(spidev_class);
 668         unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
 669 }
 670 module_exit(spidev_exit);
 671
 672 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 673 MODULE_DESCRIPTION("User mode SPI device interface");
 674 MODULE_LICENSE("GPL");