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
  19 #include <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/ioctl.h>
  22 #include <linux/fs.h>
  23 #include <linux/device.h>
  24 #include <linux/err.h>
  25 #include <linux/list.h>
  26 #include <linux/errno.h>
  27 #include <linux/mutex.h>
  28 #include <linux/slab.h>
  29 #include <linux/compat.h>
  30 #include <linux/of.h>
  31 #include <linux/of_device.h>
  32
  33 #include <linux/spi/spi.h>
  34 #include <linux/spi/spidev.h>
  35
  36 #include <linux/uaccess.h>
  37
  38
  39 /*
  40  * This supports access to SPI devices using normal userspace I/O calls.
  41  * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
  42  * and often mask message boundaries, full SPI support requires full duplex
  43  * transfers.  There are several kinds of internal message boundaries to
  44  * handle chipselect management and other protocol options.
  45  *
  46  * SPI has a character major number assigned.  We allocate minor numbers
  47  * dynamically using a bitmask.  You must use hotplug tools, such as udev
  48  * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
  49  * nodes, since there is no fixed association of minor numbers with any
  50  * particular SPI bus or device.
  51  */
  52 #define SPIDEV_MAJOR                    153     /* assigned */
  53 #define N_SPI_MINORS                    32      /* ... up to 256 */
  54
  55 static DECLARE_BITMAP(minors, N_SPI_MINORS);
  56
  57
  58 /* Bit masks for spi_device.mode management.  Note that incorrect
  59  * settings for some settings can cause *lots* of trouble for other
  60  * devices on a shared bus:
  61  *
  62  *  - CS_HIGH ... this device will be active when it shouldn't be
  63  *  - 3WIRE ... when active, it won't behave as it should
  64  *  - NO_CS ... there will be no explicit message boundaries; this
  65  *      is completely incompatible with the shared bus model
  66  *  - READY ... transfers may proceed when they shouldn't.
  67  *
  68  * REVISIT should changing those flags be privileged?
  69  */
  70 #define SPI_MODE_MASK           (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
  71                                 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
  72                                 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
  73                                 | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
  74
  75 struct spidev_data {
  76         dev_t                   devt;
  77         spinlock_t              spi_lock;
  78         struct spi_device       *spi;
  79         struct list_head        device_entry;
  80
  81         /* TX/RX buffers are NULL unless this device is open (users > 0) */
  82         struct mutex            buf_lock;
  83         unsigned                users;
  84         u8                      *tx_buffer;
  85         u8                      *rx_buffer;
  86         u32                     speed_hz;
  87 };
  88
  89 static LIST_HEAD(device_list);
  90 static DEFINE_MUTEX(device_list_lock);
  91
  92 static unsigned bufsiz = 4096;
  93 module_param(bufsiz, uint, S_IRUGO);
  94 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  95
  96 /*-------------------------------------------------------------------------*/
  97
  98 /*
  99  * We can't use the standard synchronous wrappers for file I/O; we
 100  * need to protect against async removal of the underlying spi_device.
 101  */
 102 static void spidev_complete(void *arg)
 103 {
 104         complete(arg);
 105 }
 106
 107 static ssize_t
 108 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 109 {
 110         DECLARE_COMPLETION_ONSTACK(done);
 111         int status;
 112
 113         message->complete = spidev_complete;
 114         message->context = &done;
 115
 116         spin_lock_irq(&spidev->spi_lock);
 117         if (spidev->spi == NULL)
 118                 status = -ESHUTDOWN;
 119         else
 120                 status = spi_async(spidev->spi, message);
 121         spin_unlock_irq(&spidev->spi_lock);
 122
 123         if (status == 0) {
 124                 wait_for_completion(&done);
 125                 status = message->status;
 126                 if (status == 0)
 127                         status = message->actual_length;
 128         }
 129         return status;
 130 }
 131
 132 static inline ssize_t
 133 spidev_sync_write(struct spidev_data *spidev, size_t len)
 134 {
 135         struct spi_transfer     t = {
 136                         .tx_buf         = spidev->tx_buffer,
 137                         .len            = len,
 138                         .speed_hz       = spidev->speed_hz,
 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->rx_buffer,
 152                         .len            = len,
 153                         .speed_hz       = spidev->speed_hz,
 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->rx_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->tx_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                      *tx_buf, *rx_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         tx_buf = spidev->tx_buffer;
 240         rx_buf = spidev->rx_buffer;
 241         total = 0;
 242         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 243                         n;
 244                         n--, k_tmp++, u_tmp++) {
 245                 k_tmp->len = u_tmp->len;
 246
 247                 total += k_tmp->len;
 248                 if (total > bufsiz) {
 249                         status = -EMSGSIZE;
 250                         goto done;
 251                 }
 252
 253                 if (u_tmp->rx_buf) {
 254                         k_tmp->rx_buf = rx_buf;
 255                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
 256                                                 (uintptr_t) u_tmp->rx_buf,
 257                                                 u_tmp->len))
 258                                 goto done;
 259                 }
 260                 if (u_tmp->tx_buf) {
 261                         k_tmp->tx_buf = tx_buf;
 262                         if (copy_from_user(tx_buf, (const u8 __user *)
 263                                                 (uintptr_t) u_tmp->tx_buf,
 264                                         u_tmp->len))
 265                                 goto done;
 266                 }
 267                 tx_buf += k_tmp->len;
 268                 rx_buf += k_tmp->len;
 269
 270                 k_tmp->cs_change = !!u_tmp->cs_change;
 271                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 272                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 273                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 274                 k_tmp->delay_usecs = u_tmp->delay_usecs;
 275                 k_tmp->speed_hz = u_tmp->speed_hz;
 276                 if (!k_tmp->speed_hz)
 277                         k_tmp->speed_hz = spidev->speed_hz;
 278 #ifdef VERBOSE
 279                 dev_dbg(&spidev->spi->dev,
 280                         "  xfer len %zd %s%s%s%dbits %u usec %uHz\n",
 281                         u_tmp->len,
 282                         u_tmp->rx_buf ? "rx " : "",
 283                         u_tmp->tx_buf ? "tx " : "",
 284                         u_tmp->cs_change ? "cs " : "",
 285                         u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 286                         u_tmp->delay_usecs,
 287                         u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 288 #endif
 289                 spi_message_add_tail(k_tmp, &msg);
 290         }
 291
 292         status = spidev_sync(spidev, &msg);
 293         if (status < 0)
 294                 goto done;
 295
 296         /* copy any rx data out of bounce buffer */
 297         rx_buf = spidev->rx_buffer;
 298         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 299                 if (u_tmp->rx_buf) {
 300                         if (__copy_to_user((u8 __user *)
 301                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
 302                                         u_tmp->len)) {
 303                                 status = -EFAULT;
 304                                 goto done;
 305                         }
 306                 }
 307                 rx_buf += u_tmp->len;
 308         }
 309         status = total;
 310
 311 done:
 312         kfree(k_xfers);
 313         return status;
 314 }
 315
 316 static long
 317 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 318 {
 319         int                     err = 0;
 320         int                     retval = 0;
 321         struct spidev_data      *spidev;
 322         struct spi_device       *spi;
 323         u32                     tmp;
 324         unsigned                n_ioc;
 325         struct spi_ioc_transfer *ioc;
 326
 327         /* Check type and command number */
 328         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 329                 return -ENOTTY;
 330
 331         /* Check access direction once here; don't repeat below.
 332          * IOC_DIR is from the user perspective, while access_ok is
 333          * from the kernel perspective; so they look reversed.
 334          */
 335         if (_IOC_DIR(cmd) & _IOC_READ)
 336                 err = !access_ok(VERIFY_WRITE,
 337                                 (void __user *)arg, _IOC_SIZE(cmd));
 338         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
 339                 err = !access_ok(VERIFY_READ,
 340                                 (void __user *)arg, _IOC_SIZE(cmd));
 341         if (err)
 342                 return -EFAULT;
 343
 344         /* guard against device removal before, or while,
 345          * we issue this ioctl.
 346          */
 347         spidev = filp->private_data;
 348         spin_lock_irq(&spidev->spi_lock);
 349         spi = spi_dev_get(spidev->spi);
 350         spin_unlock_irq(&spidev->spi_lock);
 351
 352         if (spi == NULL)
 353                 return -ESHUTDOWN;
 354
 355         /* use the buffer lock here for triple duty:
 356          *  - prevent I/O (from us) so calling spi_setup() is safe;
 357          *  - prevent concurrent SPI_IOC_WR_* from morphing
 358          *    data fields while SPI_IOC_RD_* reads them;
 359          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 360          */
 361         mutex_lock(&spidev->buf_lock);
 362
 363         switch (cmd) {
 364         /* read requests */
 365         case SPI_IOC_RD_MODE:
 366                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 367                                         (__u8 __user *)arg);
 368                 break;
 369         case SPI_IOC_RD_MODE32:
 370                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 371                                         (__u32 __user *)arg);
 372                 break;
 373         case SPI_IOC_RD_LSB_FIRST:
 374                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 375                                         (__u8 __user *)arg);
 376                 break;
 377         case SPI_IOC_RD_BITS_PER_WORD:
 378                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
 379                 break;
 380         case SPI_IOC_RD_MAX_SPEED_HZ:
 381                 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
 382                 break;
 383
 384         /* write requests */
 385         case SPI_IOC_WR_MODE:
 386         case SPI_IOC_WR_MODE32:
 387                 if (cmd == SPI_IOC_WR_MODE)
 388                         retval = __get_user(tmp, (u8 __user *)arg);
 389                 else
 390                         retval = __get_user(tmp, (u32 __user *)arg);
 391                 if (retval == 0) {
 392                         u32     save = spi->mode;
 393
 394                         if (tmp & ~SPI_MODE_MASK) {
 395                                 retval = -EINVAL;
 396                                 break;
 397                         }
 398
 399                         tmp |= spi->mode & ~SPI_MODE_MASK;
 400                         spi->mode = (u16)tmp;
 401                         retval = spi_setup(spi);
 402                         if (retval < 0)
 403                                 spi->mode = save;
 404                         else
 405                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 406                 }
 407                 break;
 408         case SPI_IOC_WR_LSB_FIRST:
 409                 retval = __get_user(tmp, (__u8 __user *)arg);
 410                 if (retval == 0) {
 411                         u32     save = spi->mode;
 412
 413                         if (tmp)
 414                                 spi->mode |= SPI_LSB_FIRST;
 415                         else
 416                                 spi->mode &= ~SPI_LSB_FIRST;
 417                         retval = spi_setup(spi);
 418                         if (retval < 0)
 419                                 spi->mode = save;
 420                         else
 421                                 dev_dbg(&spi->dev, "%csb first\n",
 422                                                 tmp ? 'l' : 'm');
 423                 }
 424                 break;
 425         case SPI_IOC_WR_BITS_PER_WORD:
 426                 retval = __get_user(tmp, (__u8 __user *)arg);
 427                 if (retval == 0) {
 428                         u8      save = spi->bits_per_word;
 429
 430                         spi->bits_per_word = tmp;
 431                         retval = spi_setup(spi);
 432                         if (retval < 0)
 433                                 spi->bits_per_word = save;
 434                         else
 435                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 436                 }
 437                 break;
 438         case SPI_IOC_WR_MAX_SPEED_HZ:
 439                 retval = __get_user(tmp, (__u32 __user *)arg);
 440                 if (retval == 0) {
 441                         u32     save = spi->max_speed_hz;
 442
 443                         spi->max_speed_hz = tmp;
 444                         retval = spi_setup(spi);
 445                         if (retval >= 0)
 446                                 spidev->speed_hz = tmp;
 447                         else
 448                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 449                         spi->max_speed_hz = save;
 450                 }
 451                 break;
 452
 453         default:
 454                 /* segmented and/or full-duplex I/O request */
 455                 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 456                                 || _IOC_DIR(cmd) != _IOC_WRITE) {
 457                         retval = -ENOTTY;
 458                         break;
 459                 }
 460
 461                 tmp = _IOC_SIZE(cmd);
 462                 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
 463                         retval = -EINVAL;
 464                         break;
 465                 }
 466                 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 467                 if (n_ioc == 0)
 468                         break;
 469
 470                 /* copy into scratch area */
 471                 ioc = kmalloc(tmp, GFP_KERNEL);
 472                 if (!ioc) {
 473                         retval = -ENOMEM;
 474                         break;
 475                 }
 476                 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
 477                         kfree(ioc);
 478                         retval = -EFAULT;
 479                         break;
 480                 }
 481
 482                 /* translate to spi_message, execute */
 483                 retval = spidev_message(spidev, ioc, n_ioc);
 484                 kfree(ioc);
 485                 break;
 486         }
 487
 488         mutex_unlock(&spidev->buf_lock);
 489         spi_dev_put(spi);
 490         return retval;
 491 }
 492
 493 #ifdef CONFIG_COMPAT
 494 static long
 495 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 496 {
 497         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 498 }
 499 #else
 500 #define spidev_compat_ioctl NULL
 501 #endif /* CONFIG_COMPAT */
 502
 503 static int spidev_open(struct inode *inode, struct file *filp)
 504 {
 505         struct spidev_data      *spidev;
 506         int                     status = -ENXIO;
 507
 508         mutex_lock(&device_list_lock);
 509
 510         list_for_each_entry(spidev, &device_list, device_entry) {
 511                 if (spidev->devt == inode->i_rdev) {
 512                         status = 0;
 513                         break;
 514                 }
 515         }
 516
 517         if (status) {
 518                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 519                 goto err_find_dev;
 520         }
 521
 522         if (!spidev->tx_buffer) {
 523                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 524                 if (!spidev->tx_buffer) {
 525                                 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 526                                 status = -ENOMEM;
 527                         goto err_find_dev;
 528                         }
 529                 }
 530
 531         if (!spidev->rx_buffer) {
 532                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 533                 if (!spidev->rx_buffer) {
 534                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 535                         status = -ENOMEM;
 536                         goto err_alloc_rx_buf;
 537                 }
 538         }
 539
 540         spidev->users++;
 541         filp->private_data = spidev;
 542         nonseekable_open(inode, filp);
 543
 544         mutex_unlock(&device_list_lock);
 545         return 0;
 546
 547 err_alloc_rx_buf:
 548         kfree(spidev->tx_buffer);
 549         spidev->tx_buffer = NULL;
 550 err_find_dev:
 551         mutex_unlock(&device_list_lock);
 552         return status;
 553 }
 554
 555 static int spidev_release(struct inode *inode, struct file *filp)
 556 {
 557         struct spidev_data      *spidev;
 558         int                     status = 0;
 559
 560         mutex_lock(&device_list_lock);
 561         spidev = filp->private_data;
 562         filp->private_data = NULL;
 563
 564         /* last close? */
 565         spidev->users--;
 566         if (!spidev->users) {
 567                 int             dofree;
 568
 569                 kfree(spidev->tx_buffer);
 570                 spidev->tx_buffer = NULL;
 571
 572                 kfree(spidev->rx_buffer);
 573                 spidev->rx_buffer = NULL;
 574
 575                 spidev->speed_hz = spidev->spi->max_speed_hz;
 576
 577                 /* ... after we unbound from the underlying device? */
 578                 spin_lock_irq(&spidev->spi_lock);
 579                 dofree = (spidev->spi == NULL);
 580                 spin_unlock_irq(&spidev->spi_lock);
 581
 582                 if (dofree)
 583                         kfree(spidev);
 584         }
 585         mutex_unlock(&device_list_lock);
 586
 587         return status;
 588 }
 589
 590 static const struct file_operations spidev_fops = {
 591         .owner =        THIS_MODULE,
 592         /* REVISIT switch to aio primitives, so that userspace
 593          * gets more complete API coverage.  It'll simplify things
 594          * too, except for the locking.
 595          */
 596         .write =        spidev_write,
 597         .read =         spidev_read,
 598         .unlocked_ioctl = spidev_ioctl,
 599         .compat_ioctl = spidev_compat_ioctl,
 600         .open =         spidev_open,
 601         .release =      spidev_release,
 602         .llseek =       no_llseek,
 603 };
 604
 605 /*-------------------------------------------------------------------------*/
 606
 607 /* The main reason to have this class is to make mdev/udev create the
 608  * /dev/spidevB.C character device nodes exposing our userspace API.
 609  * It also simplifies memory management.
 610  */
 611
 612 static struct class *spidev_class;
 613
 614 /*-------------------------------------------------------------------------*/
 615
 616 static int spidev_probe(struct spi_device *spi)
 617 {
 618         struct spidev_data      *spidev;
 619         int                     status;
 620         unsigned long           minor;
 621
 622         /* Allocate driver data */
 623         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 624         if (!spidev)
 625                 return -ENOMEM;
 626
 627         /* Initialize the driver data */
 628         spidev->spi = spi;
 629         spin_lock_init(&spidev->spi_lock);
 630         mutex_init(&spidev->buf_lock);
 631
 632         INIT_LIST_HEAD(&spidev->device_entry);
 633
 634         /* If we can allocate a minor number, hook up this device.
 635          * Reusing minors is fine so long as udev or mdev is working.
 636          */
 637         mutex_lock(&device_list_lock);
 638         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 639         if (minor < N_SPI_MINORS) {
 640                 struct device *dev;
 641
 642                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 643                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 644                                     spidev, "spidev%d.%d",
 645                                     spi->master->bus_num, spi->chip_select);
 646                 status = PTR_ERR_OR_ZERO(dev);
 647         } else {
 648                 dev_dbg(&spi->dev, "no minor number available!\n");
 649                 status = -ENODEV;
 650         }
 651         if (status == 0) {
 652                 set_bit(minor, minors);
 653                 list_add(&spidev->device_entry, &device_list);
 654         }
 655         mutex_unlock(&device_list_lock);
 656
 657         spidev->speed_hz = spi->max_speed_hz;
 658
 659         if (status == 0)
 660                 spi_set_drvdata(spi, spidev);
 661         else
 662                 kfree(spidev);
 663
 664         return status;
 665 }
 666
 667 static int spidev_remove(struct spi_device *spi)
 668 {
 669         struct spidev_data      *spidev = spi_get_drvdata(spi);
 670
 671         /* make sure ops on existing fds can abort cleanly */
 672         spin_lock_irq(&spidev->spi_lock);
 673         spidev->spi = NULL;
 674         spin_unlock_irq(&spidev->spi_lock);
 675
 676         /* prevent new opens */
 677         mutex_lock(&device_list_lock);
 678         list_del(&spidev->device_entry);
 679         device_destroy(spidev_class, spidev->devt);
 680         clear_bit(MINOR(spidev->devt), minors);
 681         if (spidev->users == 0)
 682                 kfree(spidev);
 683         mutex_unlock(&device_list_lock);
 684
 685         return 0;
 686 }
 687
 688 static const struct of_device_id spidev_dt_ids[] = {
 689         { .compatible = "rohm,dh2228fv" },
 690         {},
 691 };
 692
 693 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 694
 695 static struct spi_driver spidev_spi_driver = {
 696         .driver = {
 697                 .name =         "spidev",
 698                 .owner =        THIS_MODULE,
 699                 .of_match_table = of_match_ptr(spidev_dt_ids),
 700         },
 701         .probe =        spidev_probe,
 702         .remove =       spidev_remove,
 703
 704         /* NOTE:  suspend/resume methods are not necessary here.
 705          * We don't do anything except pass the requests to/from
 706          * the underlying controller.  The refrigerator handles
 707          * most issues; the controller driver handles the rest.
 708          */
 709 };
 710
 711 /*-------------------------------------------------------------------------*/
 712
 713 static int __init spidev_init(void)
 714 {
 715         int status;
 716
 717         /* Claim our 256 reserved device numbers.  Then register a class
 718          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 719          * the driver which manages those device numbers.
 720          */
 721         BUILD_BUG_ON(N_SPI_MINORS > 256);
 722         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 723         if (status < 0)
 724                 return status;
 725
 726         spidev_class = class_create(THIS_MODULE, "spidev");
 727         if (IS_ERR(spidev_class)) {
 728                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 729                 return PTR_ERR(spidev_class);
 730         }
 731
 732         status = spi_register_driver(&spidev_spi_driver);
 733         if (status < 0) {
 734                 class_destroy(spidev_class);
 735                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 736         }
 737         return status;
 738 }
 739 module_init(spidev_init);
 740
 741 static void __exit spidev_exit(void)
 742 {
 743         spi_unregister_driver(&spidev_spi_driver);
 744         class_destroy(spidev_class);
 745         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 746 }
 747 module_exit(spidev_exit);
 748
 749 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 750 MODULE_DESCRIPTION("User mode SPI device interface");
 751 MODULE_LICENSE("GPL");
 752 MODULE_ALIAS("spi:spidev");