drivers/spi/spidev.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Simple synchronous userspace interface to SPI devices
   4  *
   5  * Copyright (C) 2006 SWAPP
   6  *      Andrea Paterniani <a.paterniani@swapp-eng.it>
   7  * Copyright (C) 2007 David Brownell (simplification, cleanup)
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/ioctl.h>
  12 #include <linux/fs.h>
  13 #include <linux/device.h>
  14 #include <linux/err.h>
  15 #include <linux/list.h>
  16 #include <linux/errno.h>
  17 #include <linux/mod_devicetable.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20 #include <linux/property.h>
  21 #include <linux/slab.h>
  22 #include <linux/compat.h>
  23
  24 #include <linux/spi/spi.h>
  25 #include <linux/spi/spidev.h>
  26
  27 #include <linux/uaccess.h>
  28
  29
  30 /*
  31  * This supports access to SPI devices using normal userspace I/O calls.
  32  * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
  33  * and often mask message boundaries, full SPI support requires full duplex
  34  * transfers.  There are several kinds of internal message boundaries to
  35  * handle chipselect management and other protocol options.
  36  *
  37  * SPI has a character major number assigned.  We allocate minor numbers
  38  * dynamically using a bitmask.  You must use hotplug tools, such as udev
  39  * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
  40  * nodes, since there is no fixed association of minor numbers with any
  41  * particular SPI bus or device.
  42  */
  43 #define SPIDEV_MAJOR                    153     /* assigned */
  44 #define N_SPI_MINORS                    32      /* ... up to 256 */
  45
  46 static DECLARE_BITMAP(minors, N_SPI_MINORS);
  47
  48 static_assert(N_SPI_MINORS > 0 && N_SPI_MINORS <= 256);
  49
  50 /* Bit masks for spi_device.mode management.  Note that incorrect
  51  * settings for some settings can cause *lots* of trouble for other
  52  * devices on a shared bus:
  53  *
  54  *  - CS_HIGH ... this device will be active when it shouldn't be
  55  *  - 3WIRE ... when active, it won't behave as it should
  56  *  - NO_CS ... there will be no explicit message boundaries; this
  57  *      is completely incompatible with the shared bus model
  58  *  - READY ... transfers may proceed when they shouldn't.
  59  *
  60  * REVISIT should changing those flags be privileged?
  61  */
  62 #define SPI_MODE_MASK           (SPI_MODE_X_MASK | SPI_CS_HIGH \
  63                                 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
  64                                 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
  65                                 | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \
  66                                 | SPI_RX_QUAD | SPI_RX_OCTAL \
  67                                 | SPI_RX_CPHA_FLIP | SPI_3WIRE_HIZ \
  68                                 | SPI_MOSI_IDLE_LOW)
  69
  70 struct spidev_data {
  71         dev_t                   devt;
  72         struct mutex            spi_lock;
  73         struct spi_device       *spi;
  74         struct list_head        device_entry;
  75
  76         /* TX/RX buffers are NULL unless this device is open (users > 0) */
  77         struct mutex            buf_lock;
  78         unsigned                users;
  79         u8                      *tx_buffer;
  80         u8                      *rx_buffer;
  81         u32                     speed_hz;
  82 };
  83
  84 static LIST_HEAD(device_list);
  85 static DEFINE_MUTEX(device_list_lock);
  86
  87 static unsigned bufsiz = 4096;
  88 module_param(bufsiz, uint, S_IRUGO);
  89 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  90
  91 /*-------------------------------------------------------------------------*/
  92
  93 static ssize_t
  94 spidev_sync_unlocked(struct spi_device *spi, struct spi_message *message)
  95 {
  96         ssize_t status;
  97
  98         status = spi_sync(spi, message);
  99         if (status == 0)
 100                 status = message->actual_length;
 101
 102         return status;
 103 }
 104
 105 static ssize_t
 106 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 107 {
 108         ssize_t status;
 109         struct spi_device *spi;
 110
 111         mutex_lock(&spidev->spi_lock);
 112         spi = spidev->spi;
 113
 114         if (spi == NULL)
 115                 status = -ESHUTDOWN;
 116         else
 117                 status = spidev_sync_unlocked(spi, message);
 118
 119         mutex_unlock(&spidev->spi_lock);
 120         return status;
 121 }
 122
 123 static inline ssize_t
 124 spidev_sync_write(struct spidev_data *spidev, size_t len)
 125 {
 126         struct spi_transfer     t = {
 127                         .tx_buf         = spidev->tx_buffer,
 128                         .len            = len,
 129                         .speed_hz       = spidev->speed_hz,
 130                 };
 131         struct spi_message      m;
 132
 133         spi_message_init(&m);
 134         spi_message_add_tail(&t, &m);
 135         return spidev_sync(spidev, &m);
 136 }
 137
 138 static inline ssize_t
 139 spidev_sync_read(struct spidev_data *spidev, size_t len)
 140 {
 141         struct spi_transfer     t = {
 142                         .rx_buf         = spidev->rx_buffer,
 143                         .len            = len,
 144                         .speed_hz       = spidev->speed_hz,
 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;
 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->rx_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;
 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->tx_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, tx_total, rx_total;
 218         u8                      *tx_buf, *rx_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         tx_buf = spidev->tx_buffer;
 231         rx_buf = spidev->rx_buffer;
 232         total = 0;
 233         tx_total = 0;
 234         rx_total = 0;
 235         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 236                         n;
 237                         n--, k_tmp++, u_tmp++) {
 238                 /* Ensure that also following allocations from rx_buf/tx_buf will meet
 239                  * DMA alignment requirements.
 240                  */
 241                 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_DMA_MINALIGN);
 242
 243                 k_tmp->len = u_tmp->len;
 244
 245                 total += k_tmp->len;
 246                 /* Since the function returns the total length of transfers
 247                  * on success, restrict the total to positive int values to
 248                  * avoid the return value looking like an error.  Also check
 249                  * each transfer length to avoid arithmetic overflow.
 250                  */
 251                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 252                         status = -EMSGSIZE;
 253                         goto done;
 254                 }
 255
 256                 if (u_tmp->rx_buf) {
 257                         /* this transfer needs space in RX bounce buffer */
 258                         rx_total += len_aligned;
 259                         if (rx_total > bufsiz) {
 260                                 status = -EMSGSIZE;
 261                                 goto done;
 262                         }
 263                         k_tmp->rx_buf = rx_buf;
 264                         rx_buf += len_aligned;
 265                 }
 266                 if (u_tmp->tx_buf) {
 267                         /* this transfer needs space in TX bounce buffer */
 268                         tx_total += len_aligned;
 269                         if (tx_total > bufsiz) {
 270                                 status = -EMSGSIZE;
 271                                 goto done;
 272                         }
 273                         k_tmp->tx_buf = tx_buf;
 274                         if (copy_from_user(tx_buf, (const u8 __user *)
 275                                                 (uintptr_t) u_tmp->tx_buf,
 276                                         u_tmp->len))
 277                                 goto done;
 278                         tx_buf += len_aligned;
 279                 }
 280
 281                 k_tmp->cs_change = !!u_tmp->cs_change;
 282                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 283                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 284                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 285                 k_tmp->delay.value = u_tmp->delay_usecs;
 286                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 287                 k_tmp->speed_hz = u_tmp->speed_hz;
 288                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 289                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 290                 if (!k_tmp->speed_hz)
 291                         k_tmp->speed_hz = spidev->speed_hz;
 292 #ifdef VERBOSE
 293                 dev_dbg(&spidev->spi->dev,
 294                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 295                         k_tmp->len,
 296                         k_tmp->rx_buf ? "rx " : "",
 297                         k_tmp->tx_buf ? "tx " : "",
 298                         k_tmp->cs_change ? "cs " : "",
 299                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 300                         k_tmp->delay.value,
 301                         k_tmp->word_delay.value,
 302                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 303 #endif
 304                 spi_message_add_tail(k_tmp, &msg);
 305         }
 306
 307         status = spidev_sync_unlocked(spidev->spi, &msg);
 308         if (status < 0)
 309                 goto done;
 310
 311         /* copy any rx data out of bounce buffer */
 312         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 313                         n;
 314                         n--, k_tmp++, u_tmp++) {
 315                 if (u_tmp->rx_buf) {
 316                         if (copy_to_user((u8 __user *)
 317                                         (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
 318                                         u_tmp->len)) {
 319                                 status = -EFAULT;
 320                                 goto done;
 321                         }
 322                 }
 323         }
 324         status = total;
 325
 326 done:
 327         kfree(k_xfers);
 328         return status;
 329 }
 330
 331 static struct spi_ioc_transfer *
 332 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 333                 unsigned *n_ioc)
 334 {
 335         u32     tmp;
 336
 337         /* Check type, command number and direction */
 338         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 339                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 340                         || _IOC_DIR(cmd) != _IOC_WRITE)
 341                 return ERR_PTR(-ENOTTY);
 342
 343         tmp = _IOC_SIZE(cmd);
 344         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 345                 return ERR_PTR(-EINVAL);
 346         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 347         if (*n_ioc == 0)
 348                 return NULL;
 349
 350         /* copy into scratch area */
 351         return memdup_user(u_ioc, tmp);
 352 }
 353
 354 static long
 355 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 356 {
 357         int                     retval = 0;
 358         struct spidev_data      *spidev;
 359         struct spi_device       *spi;
 360         u32                     tmp;
 361         unsigned                n_ioc;
 362         struct spi_ioc_transfer *ioc;
 363
 364         /* Check type and command number */
 365         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 366                 return -ENOTTY;
 367
 368         /* guard against device removal before, or while,
 369          * we issue this ioctl.
 370          */
 371         spidev = filp->private_data;
 372         mutex_lock(&spidev->spi_lock);
 373         spi = spi_dev_get(spidev->spi);
 374         if (spi == NULL) {
 375                 mutex_unlock(&spidev->spi_lock);
 376                 return -ESHUTDOWN;
 377         }
 378
 379         /* use the buffer lock here for triple duty:
 380          *  - prevent I/O (from us) so calling spi_setup() is safe;
 381          *  - prevent concurrent SPI_IOC_WR_* from morphing
 382          *    data fields while SPI_IOC_RD_* reads them;
 383          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 384          */
 385         mutex_lock(&spidev->buf_lock);
 386
 387         switch (cmd) {
 388         /* read requests */
 389         case SPI_IOC_RD_MODE:
 390         case SPI_IOC_RD_MODE32:
 391                 tmp = spi->mode;
 392
 393                 {
 394                         struct spi_controller *ctlr = spi->controller;
 395
 396                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 397                             ctlr->cs_gpiods[spi_get_chipselect(spi, 0)])
 398                                 tmp &= ~SPI_CS_HIGH;
 399                 }
 400
 401                 if (cmd == SPI_IOC_RD_MODE)
 402                         retval = put_user(tmp & SPI_MODE_MASK,
 403                                           (__u8 __user *)arg);
 404                 else
 405                         retval = put_user(tmp & SPI_MODE_MASK,
 406                                           (__u32 __user *)arg);
 407                 break;
 408         case SPI_IOC_RD_LSB_FIRST:
 409                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 410                                         (__u8 __user *)arg);
 411                 break;
 412         case SPI_IOC_RD_BITS_PER_WORD:
 413                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 414                 break;
 415         case SPI_IOC_RD_MAX_SPEED_HZ:
 416                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 417                 break;
 418
 419         /* write requests */
 420         case SPI_IOC_WR_MODE:
 421         case SPI_IOC_WR_MODE32:
 422                 if (cmd == SPI_IOC_WR_MODE)
 423                         retval = get_user(tmp, (u8 __user *)arg);
 424                 else
 425                         retval = get_user(tmp, (u32 __user *)arg);
 426                 if (retval == 0) {
 427                         struct spi_controller *ctlr = spi->controller;
 428                         u32     save = spi->mode;
 429
 430                         if (tmp & ~SPI_MODE_MASK) {
 431                                 retval = -EINVAL;
 432                                 break;
 433                         }
 434
 435                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 436                             ctlr->cs_gpiods[spi_get_chipselect(spi, 0)])
 437                                 tmp |= SPI_CS_HIGH;
 438
 439                         tmp |= spi->mode & ~SPI_MODE_MASK;
 440                         spi->mode = tmp & SPI_MODE_USER_MASK;
 441                         retval = spi_setup(spi);
 442                         if (retval < 0)
 443                                 spi->mode = save;
 444                         else
 445                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 446                 }
 447                 break;
 448         case SPI_IOC_WR_LSB_FIRST:
 449                 retval = get_user(tmp, (__u8 __user *)arg);
 450                 if (retval == 0) {
 451                         u32     save = spi->mode;
 452
 453                         if (tmp)
 454                                 spi->mode |= SPI_LSB_FIRST;
 455                         else
 456                                 spi->mode &= ~SPI_LSB_FIRST;
 457                         retval = spi_setup(spi);
 458                         if (retval < 0)
 459                                 spi->mode = save;
 460                         else
 461                                 dev_dbg(&spi->dev, "%csb first\n",
 462                                                 tmp ? 'l' : 'm');
 463                 }
 464                 break;
 465         case SPI_IOC_WR_BITS_PER_WORD:
 466                 retval = get_user(tmp, (__u8 __user *)arg);
 467                 if (retval == 0) {
 468                         u8      save = spi->bits_per_word;
 469
 470                         spi->bits_per_word = tmp;
 471                         retval = spi_setup(spi);
 472                         if (retval < 0)
 473                                 spi->bits_per_word = save;
 474                         else
 475                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 476                 }
 477                 break;
 478         case SPI_IOC_WR_MAX_SPEED_HZ: {
 479                 u32 save;
 480
 481                 retval = get_user(tmp, (__u32 __user *)arg);
 482                 if (retval)
 483                         break;
 484                 if (tmp == 0) {
 485                         retval = -EINVAL;
 486                         break;
 487                 }
 488
 489                 save = spi->max_speed_hz;
 490
 491                 spi->max_speed_hz = tmp;
 492                 retval = spi_setup(spi);
 493                 if (retval == 0) {
 494                         spidev->speed_hz = tmp;
 495                         dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
 496                 }
 497
 498                 spi->max_speed_hz = save;
 499                 break;
 500         }
 501         default:
 502                 /* segmented and/or full-duplex I/O request */
 503                 /* Check message and copy into scratch area */
 504                 ioc = spidev_get_ioc_message(cmd,
 505                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 506                 if (IS_ERR(ioc)) {
 507                         retval = PTR_ERR(ioc);
 508                         break;
 509                 }
 510                 if (!ioc)
 511                         break;  /* n_ioc is also 0 */
 512
 513                 /* translate to spi_message, execute */
 514                 retval = spidev_message(spidev, ioc, n_ioc);
 515                 kfree(ioc);
 516                 break;
 517         }
 518
 519         mutex_unlock(&spidev->buf_lock);
 520         spi_dev_put(spi);
 521         mutex_unlock(&spidev->spi_lock);
 522         return retval;
 523 }
 524
 525 #ifdef CONFIG_COMPAT
 526 static long
 527 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 528                 unsigned long arg)
 529 {
 530         struct spi_ioc_transfer __user  *u_ioc;
 531         int                             retval = 0;
 532         struct spidev_data              *spidev;
 533         struct spi_device               *spi;
 534         unsigned                        n_ioc, n;
 535         struct spi_ioc_transfer         *ioc;
 536
 537         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 538
 539         /* guard against device removal before, or while,
 540          * we issue this ioctl.
 541          */
 542         spidev = filp->private_data;
 543         mutex_lock(&spidev->spi_lock);
 544         spi = spi_dev_get(spidev->spi);
 545         if (spi == NULL) {
 546                 mutex_unlock(&spidev->spi_lock);
 547                 return -ESHUTDOWN;
 548         }
 549
 550         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 551         mutex_lock(&spidev->buf_lock);
 552
 553         /* Check message and copy into scratch area */
 554         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 555         if (IS_ERR(ioc)) {
 556                 retval = PTR_ERR(ioc);
 557                 goto done;
 558         }
 559         if (!ioc)
 560                 goto done;      /* n_ioc is also 0 */
 561
 562         /* Convert buffer pointers */
 563         for (n = 0; n < n_ioc; n++) {
 564                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 565                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 566         }
 567
 568         /* translate to spi_message, execute */
 569         retval = spidev_message(spidev, ioc, n_ioc);
 570         kfree(ioc);
 571
 572 done:
 573         mutex_unlock(&spidev->buf_lock);
 574         spi_dev_put(spi);
 575         mutex_unlock(&spidev->spi_lock);
 576         return retval;
 577 }
 578
 579 static long
 580 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 581 {
 582         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 583                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 584                         && _IOC_DIR(cmd) == _IOC_WRITE)
 585                 return spidev_compat_ioc_message(filp, cmd, arg);
 586
 587         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 588 }
 589 #else
 590 #define spidev_compat_ioctl NULL
 591 #endif /* CONFIG_COMPAT */
 592
 593 static int spidev_open(struct inode *inode, struct file *filp)
 594 {
 595         struct spidev_data      *spidev = NULL, *iter;
 596         int                     status = -ENXIO;
 597
 598         mutex_lock(&device_list_lock);
 599
 600         list_for_each_entry(iter, &device_list, device_entry) {
 601                 if (iter->devt == inode->i_rdev) {
 602                         status = 0;
 603                         spidev = iter;
 604                         break;
 605                 }
 606         }
 607
 608         if (!spidev) {
 609                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 610                 goto err_find_dev;
 611         }
 612
 613         if (!spidev->tx_buffer) {
 614                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 615                 if (!spidev->tx_buffer) {
 616                         status = -ENOMEM;
 617                         goto err_find_dev;
 618                 }
 619         }
 620
 621         if (!spidev->rx_buffer) {
 622                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 623                 if (!spidev->rx_buffer) {
 624                         status = -ENOMEM;
 625                         goto err_alloc_rx_buf;
 626                 }
 627         }
 628
 629         spidev->users++;
 630         filp->private_data = spidev;
 631         stream_open(inode, filp);
 632
 633         mutex_unlock(&device_list_lock);
 634         return 0;
 635
 636 err_alloc_rx_buf:
 637         kfree(spidev->tx_buffer);
 638         spidev->tx_buffer = NULL;
 639 err_find_dev:
 640         mutex_unlock(&device_list_lock);
 641         return status;
 642 }
 643
 644 static int spidev_release(struct inode *inode, struct file *filp)
 645 {
 646         struct spidev_data      *spidev;
 647         int                     dofree;
 648
 649         mutex_lock(&device_list_lock);
 650         spidev = filp->private_data;
 651         filp->private_data = NULL;
 652
 653         mutex_lock(&spidev->spi_lock);
 654         /* ... after we unbound from the underlying device? */
 655         dofree = (spidev->spi == NULL);
 656         mutex_unlock(&spidev->spi_lock);
 657
 658         /* last close? */
 659         spidev->users--;
 660         if (!spidev->users) {
 661
 662                 kfree(spidev->tx_buffer);
 663                 spidev->tx_buffer = NULL;
 664
 665                 kfree(spidev->rx_buffer);
 666                 spidev->rx_buffer = NULL;
 667
 668                 if (dofree)
 669                         kfree(spidev);
 670                 else
 671                         spidev->speed_hz = spidev->spi->max_speed_hz;
 672         }
 673 #ifdef CONFIG_SPI_SLAVE
 674         if (!dofree)
 675                 spi_slave_abort(spidev->spi);
 676 #endif
 677         mutex_unlock(&device_list_lock);
 678
 679         return 0;
 680 }
 681
 682 static const struct file_operations spidev_fops = {
 683         .owner =        THIS_MODULE,
 684         /* REVISIT switch to aio primitives, so that userspace
 685          * gets more complete API coverage.  It'll simplify things
 686          * too, except for the locking.
 687          */
 688         .write =        spidev_write,
 689         .read =         spidev_read,
 690         .unlocked_ioctl = spidev_ioctl,
 691         .compat_ioctl = spidev_compat_ioctl,
 692         .open =         spidev_open,
 693         .release =      spidev_release,
 694         .llseek =       no_llseek,
 695 };
 696
 697 /*-------------------------------------------------------------------------*/
 698
 699 /* The main reason to have this class is to make mdev/udev create the
 700  * /dev/spidevB.C character device nodes exposing our userspace API.
 701  * It also simplifies memory management.
 702  */
 703
 704 static struct class *spidev_class;
 705
 706 static const struct spi_device_id spidev_spi_ids[] = {
 707         { .name = "dh2228fv" },
 708         { .name = "ltc2488" },
 709         { .name = "sx1301" },
 710         { .name = "bk4" },
 711         { .name = "dhcom-board" },
 712         { .name = "m53cpld" },
 713         { .name = "spi-petra" },
 714         { .name = "spi-authenta" },
 715         { .name = "em3581" },
 716         { .name = "si3210" },
 717         {},
 718 };
 719 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
 720
 721 /*
 722  * spidev should never be referenced in DT without a specific compatible string,
 723  * it is a Linux implementation thing rather than a description of the hardware.
 724  */
 725 static int spidev_of_check(struct device *dev)
 726 {
 727         if (device_property_match_string(dev, "compatible", "spidev") < 0)
 728                 return 0;
 729
 730         dev_err(dev, "spidev listed directly in DT is not supported\n");
 731         return -EINVAL;
 732 }
 733
 734 static const struct of_device_id spidev_dt_ids[] = {
 735         { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
 736         { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
 737         { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
 738         { .compatible = "lwn,bk4", .data = &spidev_of_check },
 739         { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
 740         { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
 741         { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
 742         { .compatible = "semtech,sx1301", .data = &spidev_of_check },
 743         { .compatible = "silabs,em3581", .data = &spidev_of_check },
 744         { .compatible = "silabs,si3210", .data = &spidev_of_check },
 745         {},
 746 };
 747 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 748
 749 /* Dummy SPI devices not to be used in production systems */
 750 static int spidev_acpi_check(struct device *dev)
 751 {
 752         dev_warn(dev, "do not use this driver in production systems!\n");
 753         return 0;
 754 }
 755
 756 static const struct acpi_device_id spidev_acpi_ids[] = {
 757         /*
 758          * The ACPI SPT000* devices are only meant for development and
 759          * testing. Systems used in production should have a proper ACPI
 760          * description of the connected peripheral and they should also use
 761          * a proper driver instead of poking directly to the SPI bus.
 762          */
 763         { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
 764         { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
 765         { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
 766         {},
 767 };
 768 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 769
 770 /*-------------------------------------------------------------------------*/
 771
 772 static int spidev_probe(struct spi_device *spi)
 773 {
 774         int (*match)(struct device *dev);
 775         struct spidev_data      *spidev;
 776         int                     status;
 777         unsigned long           minor;
 778
 779         match = device_get_match_data(&spi->dev);
 780         if (match) {
 781                 status = match(&spi->dev);
 782                 if (status)
 783                         return status;
 784         }
 785
 786         /* Allocate driver data */
 787         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 788         if (!spidev)
 789                 return -ENOMEM;
 790
 791         /* Initialize the driver data */
 792         spidev->spi = spi;
 793         mutex_init(&spidev->spi_lock);
 794         mutex_init(&spidev->buf_lock);
 795
 796         INIT_LIST_HEAD(&spidev->device_entry);
 797
 798         /* If we can allocate a minor number, hook up this device.
 799          * Reusing minors is fine so long as udev or mdev is working.
 800          */
 801         mutex_lock(&device_list_lock);
 802         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 803         if (minor < N_SPI_MINORS) {
 804                 struct device *dev;
 805
 806                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 807                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 808                                     spidev, "spidev%d.%d",
 809                                     spi->master->bus_num, spi_get_chipselect(spi, 0));
 810                 status = PTR_ERR_OR_ZERO(dev);
 811         } else {
 812                 dev_dbg(&spi->dev, "no minor number available!\n");
 813                 status = -ENODEV;
 814         }
 815         if (status == 0) {
 816                 set_bit(minor, minors);
 817                 list_add(&spidev->device_entry, &device_list);
 818         }
 819         mutex_unlock(&device_list_lock);
 820
 821         spidev->speed_hz = spi->max_speed_hz;
 822
 823         if (status == 0)
 824                 spi_set_drvdata(spi, spidev);
 825         else
 826                 kfree(spidev);
 827
 828         return status;
 829 }
 830
 831 static void spidev_remove(struct spi_device *spi)
 832 {
 833         struct spidev_data      *spidev = spi_get_drvdata(spi);
 834
 835         /* prevent new opens */
 836         mutex_lock(&device_list_lock);
 837         /* make sure ops on existing fds can abort cleanly */
 838         mutex_lock(&spidev->spi_lock);
 839         spidev->spi = NULL;
 840         mutex_unlock(&spidev->spi_lock);
 841
 842         list_del(&spidev->device_entry);
 843         device_destroy(spidev_class, spidev->devt);
 844         clear_bit(MINOR(spidev->devt), minors);
 845         if (spidev->users == 0)
 846                 kfree(spidev);
 847         mutex_unlock(&device_list_lock);
 848 }
 849
 850 static struct spi_driver spidev_spi_driver = {
 851         .driver = {
 852                 .name =         "spidev",
 853                 .of_match_table = spidev_dt_ids,
 854                 .acpi_match_table = spidev_acpi_ids,
 855         },
 856         .probe =        spidev_probe,
 857         .remove =       spidev_remove,
 858         .id_table =     spidev_spi_ids,
 859
 860         /* NOTE:  suspend/resume methods are not necessary here.
 861          * We don't do anything except pass the requests to/from
 862          * the underlying controller.  The refrigerator handles
 863          * most issues; the controller driver handles the rest.
 864          */
 865 };
 866
 867 /*-------------------------------------------------------------------------*/
 868
 869 static int __init spidev_init(void)
 870 {
 871         int status;
 872
 873         /* Claim our 256 reserved device numbers.  Then register a class
 874          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 875          * the driver which manages those device numbers.
 876          */
 877         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 878         if (status < 0)
 879                 return status;
 880
 881         spidev_class = class_create("spidev");
 882         if (IS_ERR(spidev_class)) {
 883                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 884                 return PTR_ERR(spidev_class);
 885         }
 886
 887         status = spi_register_driver(&spidev_spi_driver);
 888         if (status < 0) {
 889                 class_destroy(spidev_class);
 890                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 891         }
 892         return status;
 893 }
 894 module_init(spidev_init);
 895
 896 static void __exit spidev_exit(void)
 897 {
 898         spi_unregister_driver(&spidev_spi_driver);
 899         class_destroy(spidev_class);
 900         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 901 }
 902 module_exit(spidev_exit);
 903
 904 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 905 MODULE_DESCRIPTION("User mode SPI device interface");
 906 MODULE_LICENSE("GPL");
 907 MODULE_ALIAS("spi:spidev");