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)
  68
  69 struct spidev_data {
  70         dev_t                   devt;
  71         spinlock_t              spi_lock;
  72         struct spi_device       *spi;
  73         struct list_head        device_entry;
  74
  75         /* TX/RX buffers are NULL unless this device is open (users > 0) */
  76         struct mutex            buf_lock;
  77         unsigned                users;
  78         u8                      *tx_buffer;
  79         u8                      *rx_buffer;
  80         u32                     speed_hz;
  81 };
  82
  83 static LIST_HEAD(device_list);
  84 static DEFINE_MUTEX(device_list_lock);
  85
  86 static unsigned bufsiz = 4096;
  87 module_param(bufsiz, uint, S_IRUGO);
  88 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  89
  90 /*-------------------------------------------------------------------------*/
  91
  92 static ssize_t
  93 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
  94 {
  95         int status;
  96         struct spi_device *spi;
  97
  98         spin_lock_irq(&spidev->spi_lock);
  99         spi = spidev->spi;
 100         spin_unlock_irq(&spidev->spi_lock);
 101
 102         if (spi == NULL)
 103                 status = -ESHUTDOWN;
 104         else
 105                 status = spi_sync(spi, message);
 106
 107         if (status == 0)
 108                 status = message->actual_length;
 109
 110         return status;
 111 }
 112
 113 static inline ssize_t
 114 spidev_sync_write(struct spidev_data *spidev, size_t len)
 115 {
 116         struct spi_transfer     t = {
 117                         .tx_buf         = spidev->tx_buffer,
 118                         .len            = len,
 119                         .speed_hz       = spidev->speed_hz,
 120                 };
 121         struct spi_message      m;
 122
 123         spi_message_init(&m);
 124         spi_message_add_tail(&t, &m);
 125         return spidev_sync(spidev, &m);
 126 }
 127
 128 static inline ssize_t
 129 spidev_sync_read(struct spidev_data *spidev, size_t len)
 130 {
 131         struct spi_transfer     t = {
 132                         .rx_buf         = spidev->rx_buffer,
 133                         .len            = len,
 134                         .speed_hz       = spidev->speed_hz,
 135                 };
 136         struct spi_message      m;
 137
 138         spi_message_init(&m);
 139         spi_message_add_tail(&t, &m);
 140         return spidev_sync(spidev, &m);
 141 }
 142
 143 /*-------------------------------------------------------------------------*/
 144
 145 /* Read-only message with current device setup */
 146 static ssize_t
 147 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 148 {
 149         struct spidev_data      *spidev;
 150         ssize_t                 status;
 151
 152         /* chipselect only toggles at start or end of operation */
 153         if (count > bufsiz)
 154                 return -EMSGSIZE;
 155
 156         spidev = filp->private_data;
 157
 158         mutex_lock(&spidev->buf_lock);
 159         status = spidev_sync_read(spidev, count);
 160         if (status > 0) {
 161                 unsigned long   missing;
 162
 163                 missing = copy_to_user(buf, spidev->rx_buffer, status);
 164                 if (missing == status)
 165                         status = -EFAULT;
 166                 else
 167                         status = status - missing;
 168         }
 169         mutex_unlock(&spidev->buf_lock);
 170
 171         return status;
 172 }
 173
 174 /* Write-only message with current device setup */
 175 static ssize_t
 176 spidev_write(struct file *filp, const char __user *buf,
 177                 size_t count, loff_t *f_pos)
 178 {
 179         struct spidev_data      *spidev;
 180         ssize_t                 status;
 181         unsigned long           missing;
 182
 183         /* chipselect only toggles at start or end of operation */
 184         if (count > bufsiz)
 185                 return -EMSGSIZE;
 186
 187         spidev = filp->private_data;
 188
 189         mutex_lock(&spidev->buf_lock);
 190         missing = copy_from_user(spidev->tx_buffer, buf, count);
 191         if (missing == 0)
 192                 status = spidev_sync_write(spidev, count);
 193         else
 194                 status = -EFAULT;
 195         mutex_unlock(&spidev->buf_lock);
 196
 197         return status;
 198 }
 199
 200 static int spidev_message(struct spidev_data *spidev,
 201                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 202 {
 203         struct spi_message      msg;
 204         struct spi_transfer     *k_xfers;
 205         struct spi_transfer     *k_tmp;
 206         struct spi_ioc_transfer *u_tmp;
 207         unsigned                n, total, tx_total, rx_total;
 208         u8                      *tx_buf, *rx_buf;
 209         int                     status = -EFAULT;
 210
 211         spi_message_init(&msg);
 212         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 213         if (k_xfers == NULL)
 214                 return -ENOMEM;
 215
 216         /* Construct spi_message, copying any tx data to bounce buffer.
 217          * We walk the array of user-provided transfers, using each one
 218          * to initialize a kernel version of the same transfer.
 219          */
 220         tx_buf = spidev->tx_buffer;
 221         rx_buf = spidev->rx_buffer;
 222         total = 0;
 223         tx_total = 0;
 224         rx_total = 0;
 225         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 226                         n;
 227                         n--, k_tmp++, u_tmp++) {
 228                 /* Ensure that also following allocations from rx_buf/tx_buf will meet
 229                  * DMA alignment requirements.
 230                  */
 231                 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN);
 232
 233                 k_tmp->len = u_tmp->len;
 234
 235                 total += k_tmp->len;
 236                 /* Since the function returns the total length of transfers
 237                  * on success, restrict the total to positive int values to
 238                  * avoid the return value looking like an error.  Also check
 239                  * each transfer length to avoid arithmetic overflow.
 240                  */
 241                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 242                         status = -EMSGSIZE;
 243                         goto done;
 244                 }
 245
 246                 if (u_tmp->rx_buf) {
 247                         /* this transfer needs space in RX bounce buffer */
 248                         rx_total += len_aligned;
 249                         if (rx_total > bufsiz) {
 250                                 status = -EMSGSIZE;
 251                                 goto done;
 252                         }
 253                         k_tmp->rx_buf = rx_buf;
 254                         rx_buf += len_aligned;
 255                 }
 256                 if (u_tmp->tx_buf) {
 257                         /* this transfer needs space in TX bounce buffer */
 258                         tx_total += len_aligned;
 259                         if (tx_total > bufsiz) {
 260                                 status = -EMSGSIZE;
 261                                 goto done;
 262                         }
 263                         k_tmp->tx_buf = tx_buf;
 264                         if (copy_from_user(tx_buf, (const u8 __user *)
 265                                                 (uintptr_t) u_tmp->tx_buf,
 266                                         u_tmp->len))
 267                                 goto done;
 268                         tx_buf += len_aligned;
 269                 }
 270
 271                 k_tmp->cs_change = !!u_tmp->cs_change;
 272                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 273                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 274                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 275                 k_tmp->delay.value = u_tmp->delay_usecs;
 276                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 277                 k_tmp->speed_hz = u_tmp->speed_hz;
 278                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 279                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 280                 if (!k_tmp->speed_hz)
 281                         k_tmp->speed_hz = spidev->speed_hz;
 282 #ifdef VERBOSE
 283                 dev_dbg(&spidev->spi->dev,
 284                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 285                         k_tmp->len,
 286                         k_tmp->rx_buf ? "rx " : "",
 287                         k_tmp->tx_buf ? "tx " : "",
 288                         k_tmp->cs_change ? "cs " : "",
 289                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 290                         k_tmp->delay.value,
 291                         k_tmp->word_delay.value,
 292                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 293 #endif
 294                 spi_message_add_tail(k_tmp, &msg);
 295         }
 296
 297         status = spidev_sync(spidev, &msg);
 298         if (status < 0)
 299                 goto done;
 300
 301         /* copy any rx data out of bounce buffer */
 302         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 303                         n;
 304                         n--, k_tmp++, u_tmp++) {
 305                 if (u_tmp->rx_buf) {
 306                         if (copy_to_user((u8 __user *)
 307                                         (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
 308                                         u_tmp->len)) {
 309                                 status = -EFAULT;
 310                                 goto done;
 311                         }
 312                 }
 313         }
 314         status = total;
 315
 316 done:
 317         kfree(k_xfers);
 318         return status;
 319 }
 320
 321 static struct spi_ioc_transfer *
 322 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 323                 unsigned *n_ioc)
 324 {
 325         u32     tmp;
 326
 327         /* Check type, command number and direction */
 328         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 329                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 330                         || _IOC_DIR(cmd) != _IOC_WRITE)
 331                 return ERR_PTR(-ENOTTY);
 332
 333         tmp = _IOC_SIZE(cmd);
 334         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 335                 return ERR_PTR(-EINVAL);
 336         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 337         if (*n_ioc == 0)
 338                 return NULL;
 339
 340         /* copy into scratch area */
 341         return memdup_user(u_ioc, tmp);
 342 }
 343
 344 static long
 345 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 346 {
 347         int                     retval = 0;
 348         struct spidev_data      *spidev;
 349         struct spi_device       *spi;
 350         u32                     tmp;
 351         unsigned                n_ioc;
 352         struct spi_ioc_transfer *ioc;
 353
 354         /* Check type and command number */
 355         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 356                 return -ENOTTY;
 357
 358         /* guard against device removal before, or while,
 359          * we issue this ioctl.
 360          */
 361         spidev = filp->private_data;
 362         spin_lock_irq(&spidev->spi_lock);
 363         spi = spi_dev_get(spidev->spi);
 364         spin_unlock_irq(&spidev->spi_lock);
 365
 366         if (spi == NULL)
 367                 return -ESHUTDOWN;
 368
 369         /* use the buffer lock here for triple duty:
 370          *  - prevent I/O (from us) so calling spi_setup() is safe;
 371          *  - prevent concurrent SPI_IOC_WR_* from morphing
 372          *    data fields while SPI_IOC_RD_* reads them;
 373          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 374          */
 375         mutex_lock(&spidev->buf_lock);
 376
 377         switch (cmd) {
 378         /* read requests */
 379         case SPI_IOC_RD_MODE:
 380                 retval = put_user(spi->mode & SPI_MODE_MASK,
 381                                         (__u8 __user *)arg);
 382                 break;
 383         case SPI_IOC_RD_MODE32:
 384                 retval = put_user(spi->mode & SPI_MODE_MASK,
 385                                         (__u32 __user *)arg);
 386                 break;
 387         case SPI_IOC_RD_LSB_FIRST:
 388                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 389                                         (__u8 __user *)arg);
 390                 break;
 391         case SPI_IOC_RD_BITS_PER_WORD:
 392                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 393                 break;
 394         case SPI_IOC_RD_MAX_SPEED_HZ:
 395                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 396                 break;
 397
 398         /* write requests */
 399         case SPI_IOC_WR_MODE:
 400         case SPI_IOC_WR_MODE32:
 401                 if (cmd == SPI_IOC_WR_MODE)
 402                         retval = get_user(tmp, (u8 __user *)arg);
 403                 else
 404                         retval = get_user(tmp, (u32 __user *)arg);
 405                 if (retval == 0) {
 406                         struct spi_controller *ctlr = spi->controller;
 407                         u32     save = spi->mode;
 408
 409                         if (tmp & ~SPI_MODE_MASK) {
 410                                 retval = -EINVAL;
 411                                 break;
 412                         }
 413
 414                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 415                             ctlr->cs_gpiods[spi->chip_select])
 416                                 tmp |= SPI_CS_HIGH;
 417
 418                         tmp |= spi->mode & ~SPI_MODE_MASK;
 419                         spi->mode = tmp & SPI_MODE_USER_MASK;
 420                         retval = spi_setup(spi);
 421                         if (retval < 0)
 422                                 spi->mode = save;
 423                         else
 424                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 425                 }
 426                 break;
 427         case SPI_IOC_WR_LSB_FIRST:
 428                 retval = get_user(tmp, (__u8 __user *)arg);
 429                 if (retval == 0) {
 430                         u32     save = spi->mode;
 431
 432                         if (tmp)
 433                                 spi->mode |= SPI_LSB_FIRST;
 434                         else
 435                                 spi->mode &= ~SPI_LSB_FIRST;
 436                         retval = spi_setup(spi);
 437                         if (retval < 0)
 438                                 spi->mode = save;
 439                         else
 440                                 dev_dbg(&spi->dev, "%csb first\n",
 441                                                 tmp ? 'l' : 'm');
 442                 }
 443                 break;
 444         case SPI_IOC_WR_BITS_PER_WORD:
 445                 retval = get_user(tmp, (__u8 __user *)arg);
 446                 if (retval == 0) {
 447                         u8      save = spi->bits_per_word;
 448
 449                         spi->bits_per_word = tmp;
 450                         retval = spi_setup(spi);
 451                         if (retval < 0)
 452                                 spi->bits_per_word = save;
 453                         else
 454                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 455                 }
 456                 break;
 457         case SPI_IOC_WR_MAX_SPEED_HZ: {
 458                 u32 save;
 459
 460                 retval = get_user(tmp, (__u32 __user *)arg);
 461                 if (retval)
 462                         break;
 463                 if (tmp == 0) {
 464                         retval = -EINVAL;
 465                         break;
 466                 }
 467
 468                 save = spi->max_speed_hz;
 469
 470                 spi->max_speed_hz = tmp;
 471                 retval = spi_setup(spi);
 472                 if (retval == 0) {
 473                         spidev->speed_hz = tmp;
 474                         dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
 475                 }
 476
 477                 spi->max_speed_hz = save;
 478                 break;
 479         }
 480         default:
 481                 /* segmented and/or full-duplex I/O request */
 482                 /* Check message and copy into scratch area */
 483                 ioc = spidev_get_ioc_message(cmd,
 484                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 485                 if (IS_ERR(ioc)) {
 486                         retval = PTR_ERR(ioc);
 487                         break;
 488                 }
 489                 if (!ioc)
 490                         break;  /* n_ioc is also 0 */
 491
 492                 /* translate to spi_message, execute */
 493                 retval = spidev_message(spidev, ioc, n_ioc);
 494                 kfree(ioc);
 495                 break;
 496         }
 497
 498         mutex_unlock(&spidev->buf_lock);
 499         spi_dev_put(spi);
 500         return retval;
 501 }
 502
 503 #ifdef CONFIG_COMPAT
 504 static long
 505 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 506                 unsigned long arg)
 507 {
 508         struct spi_ioc_transfer __user  *u_ioc;
 509         int                             retval = 0;
 510         struct spidev_data              *spidev;
 511         struct spi_device               *spi;
 512         unsigned                        n_ioc, n;
 513         struct spi_ioc_transfer         *ioc;
 514
 515         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 516
 517         /* guard against device removal before, or while,
 518          * we issue this ioctl.
 519          */
 520         spidev = filp->private_data;
 521         spin_lock_irq(&spidev->spi_lock);
 522         spi = spi_dev_get(spidev->spi);
 523         spin_unlock_irq(&spidev->spi_lock);
 524
 525         if (spi == NULL)
 526                 return -ESHUTDOWN;
 527
 528         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 529         mutex_lock(&spidev->buf_lock);
 530
 531         /* Check message and copy into scratch area */
 532         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 533         if (IS_ERR(ioc)) {
 534                 retval = PTR_ERR(ioc);
 535                 goto done;
 536         }
 537         if (!ioc)
 538                 goto done;      /* n_ioc is also 0 */
 539
 540         /* Convert buffer pointers */
 541         for (n = 0; n < n_ioc; n++) {
 542                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 543                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 544         }
 545
 546         /* translate to spi_message, execute */
 547         retval = spidev_message(spidev, ioc, n_ioc);
 548         kfree(ioc);
 549
 550 done:
 551         mutex_unlock(&spidev->buf_lock);
 552         spi_dev_put(spi);
 553         return retval;
 554 }
 555
 556 static long
 557 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 558 {
 559         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 560                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 561                         && _IOC_DIR(cmd) == _IOC_WRITE)
 562                 return spidev_compat_ioc_message(filp, cmd, arg);
 563
 564         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 565 }
 566 #else
 567 #define spidev_compat_ioctl NULL
 568 #endif /* CONFIG_COMPAT */
 569
 570 static int spidev_open(struct inode *inode, struct file *filp)
 571 {
 572         struct spidev_data      *spidev = NULL, *iter;
 573         int                     status = -ENXIO;
 574
 575         mutex_lock(&device_list_lock);
 576
 577         list_for_each_entry(iter, &device_list, device_entry) {
 578                 if (iter->devt == inode->i_rdev) {
 579                         status = 0;
 580                         spidev = iter;
 581                         break;
 582                 }
 583         }
 584
 585         if (!spidev) {
 586                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 587                 goto err_find_dev;
 588         }
 589
 590         if (!spidev->tx_buffer) {
 591                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 592                 if (!spidev->tx_buffer) {
 593                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 594                         status = -ENOMEM;
 595                         goto err_find_dev;
 596                 }
 597         }
 598
 599         if (!spidev->rx_buffer) {
 600                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 601                 if (!spidev->rx_buffer) {
 602                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 603                         status = -ENOMEM;
 604                         goto err_alloc_rx_buf;
 605                 }
 606         }
 607
 608         spidev->users++;
 609         filp->private_data = spidev;
 610         stream_open(inode, filp);
 611
 612         mutex_unlock(&device_list_lock);
 613         return 0;
 614
 615 err_alloc_rx_buf:
 616         kfree(spidev->tx_buffer);
 617         spidev->tx_buffer = NULL;
 618 err_find_dev:
 619         mutex_unlock(&device_list_lock);
 620         return status;
 621 }
 622
 623 static int spidev_release(struct inode *inode, struct file *filp)
 624 {
 625         struct spidev_data      *spidev;
 626         int                     dofree;
 627
 628         mutex_lock(&device_list_lock);
 629         spidev = filp->private_data;
 630         filp->private_data = NULL;
 631
 632         spin_lock_irq(&spidev->spi_lock);
 633         /* ... after we unbound from the underlying device? */
 634         dofree = (spidev->spi == NULL);
 635         spin_unlock_irq(&spidev->spi_lock);
 636
 637         /* last close? */
 638         spidev->users--;
 639         if (!spidev->users) {
 640
 641                 kfree(spidev->tx_buffer);
 642                 spidev->tx_buffer = NULL;
 643
 644                 kfree(spidev->rx_buffer);
 645                 spidev->rx_buffer = NULL;
 646
 647                 if (dofree)
 648                         kfree(spidev);
 649                 else
 650                         spidev->speed_hz = spidev->spi->max_speed_hz;
 651         }
 652 #ifdef CONFIG_SPI_SLAVE
 653         if (!dofree)
 654                 spi_slave_abort(spidev->spi);
 655 #endif
 656         mutex_unlock(&device_list_lock);
 657
 658         return 0;
 659 }
 660
 661 static const struct file_operations spidev_fops = {
 662         .owner =        THIS_MODULE,
 663         /* REVISIT switch to aio primitives, so that userspace
 664          * gets more complete API coverage.  It'll simplify things
 665          * too, except for the locking.
 666          */
 667         .write =        spidev_write,
 668         .read =         spidev_read,
 669         .unlocked_ioctl = spidev_ioctl,
 670         .compat_ioctl = spidev_compat_ioctl,
 671         .open =         spidev_open,
 672         .release =      spidev_release,
 673         .llseek =       no_llseek,
 674 };
 675
 676 /*-------------------------------------------------------------------------*/
 677
 678 /* The main reason to have this class is to make mdev/udev create the
 679  * /dev/spidevB.C character device nodes exposing our userspace API.
 680  * It also simplifies memory management.
 681  */
 682
 683 static struct class *spidev_class;
 684
 685 static const struct spi_device_id spidev_spi_ids[] = {
 686         { .name = "dh2228fv" },
 687         { .name = "ltc2488" },
 688         { .name = "sx1301" },
 689         { .name = "bk4" },
 690         { .name = "dhcom-board" },
 691         { .name = "m53cpld" },
 692         { .name = "spi-petra" },
 693         { .name = "spi-authenta" },
 694         {},
 695 };
 696 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
 697
 698 /*
 699  * spidev should never be referenced in DT without a specific compatible string,
 700  * it is a Linux implementation thing rather than a description of the hardware.
 701  */
 702 static int spidev_of_check(struct device *dev)
 703 {
 704         if (device_property_match_string(dev, "compatible", "spidev") < 0)
 705                 return 0;
 706
 707         dev_err(dev, "spidev listed directly in DT is not supported\n");
 708         return -EINVAL;
 709 }
 710
 711 static const struct of_device_id spidev_dt_ids[] = {
 712         { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
 713         { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
 714         { .compatible = "semtech,sx1301", .data = &spidev_of_check },
 715         { .compatible = "lwn,bk4", .data = &spidev_of_check },
 716         { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
 717         { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
 718         { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
 719         { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
 720         {},
 721 };
 722 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 723
 724 /* Dummy SPI devices not to be used in production systems */
 725 static int spidev_acpi_check(struct device *dev)
 726 {
 727         dev_warn(dev, "do not use this driver in production systems!\n");
 728         return 0;
 729 }
 730
 731 static const struct acpi_device_id spidev_acpi_ids[] = {
 732         /*
 733          * The ACPI SPT000* devices are only meant for development and
 734          * testing. Systems used in production should have a proper ACPI
 735          * description of the connected peripheral and they should also use
 736          * a proper driver instead of poking directly to the SPI bus.
 737          */
 738         { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
 739         { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
 740         { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
 741         {},
 742 };
 743 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 744
 745 /*-------------------------------------------------------------------------*/
 746
 747 static int spidev_probe(struct spi_device *spi)
 748 {
 749         int (*match)(struct device *dev);
 750         struct spidev_data      *spidev;
 751         int                     status;
 752         unsigned long           minor;
 753
 754         match = device_get_match_data(&spi->dev);
 755         if (match) {
 756                 status = match(&spi->dev);
 757                 if (status)
 758                         return status;
 759         }
 760
 761         /* Allocate driver data */
 762         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 763         if (!spidev)
 764                 return -ENOMEM;
 765
 766         /* Initialize the driver data */
 767         spidev->spi = spi;
 768         spin_lock_init(&spidev->spi_lock);
 769         mutex_init(&spidev->buf_lock);
 770
 771         INIT_LIST_HEAD(&spidev->device_entry);
 772
 773         /* If we can allocate a minor number, hook up this device.
 774          * Reusing minors is fine so long as udev or mdev is working.
 775          */
 776         mutex_lock(&device_list_lock);
 777         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 778         if (minor < N_SPI_MINORS) {
 779                 struct device *dev;
 780
 781                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 782                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 783                                     spidev, "spidev%d.%d",
 784                                     spi->master->bus_num, spi->chip_select);
 785                 status = PTR_ERR_OR_ZERO(dev);
 786         } else {
 787                 dev_dbg(&spi->dev, "no minor number available!\n");
 788                 status = -ENODEV;
 789         }
 790         if (status == 0) {
 791                 set_bit(minor, minors);
 792                 list_add(&spidev->device_entry, &device_list);
 793         }
 794         mutex_unlock(&device_list_lock);
 795
 796         spidev->speed_hz = spi->max_speed_hz;
 797
 798         if (status == 0)
 799                 spi_set_drvdata(spi, spidev);
 800         else
 801                 kfree(spidev);
 802
 803         return status;
 804 }
 805
 806 static void spidev_remove(struct spi_device *spi)
 807 {
 808         struct spidev_data      *spidev = spi_get_drvdata(spi);
 809
 810         /* prevent new opens */
 811         mutex_lock(&device_list_lock);
 812         /* make sure ops on existing fds can abort cleanly */
 813         spin_lock_irq(&spidev->spi_lock);
 814         spidev->spi = NULL;
 815         spin_unlock_irq(&spidev->spi_lock);
 816
 817         list_del(&spidev->device_entry);
 818         device_destroy(spidev_class, spidev->devt);
 819         clear_bit(MINOR(spidev->devt), minors);
 820         if (spidev->users == 0)
 821                 kfree(spidev);
 822         mutex_unlock(&device_list_lock);
 823 }
 824
 825 static struct spi_driver spidev_spi_driver = {
 826         .driver = {
 827                 .name =         "spidev",
 828                 .of_match_table = spidev_dt_ids,
 829                 .acpi_match_table = spidev_acpi_ids,
 830         },
 831         .probe =        spidev_probe,
 832         .remove =       spidev_remove,
 833         .id_table =     spidev_spi_ids,
 834
 835         /* NOTE:  suspend/resume methods are not necessary here.
 836          * We don't do anything except pass the requests to/from
 837          * the underlying controller.  The refrigerator handles
 838          * most issues; the controller driver handles the rest.
 839          */
 840 };
 841
 842 /*-------------------------------------------------------------------------*/
 843
 844 static int __init spidev_init(void)
 845 {
 846         int status;
 847
 848         /* Claim our 256 reserved device numbers.  Then register a class
 849          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 850          * the driver which manages those device numbers.
 851          */
 852         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 853         if (status < 0)
 854                 return status;
 855
 856         spidev_class = class_create(THIS_MODULE, "spidev");
 857         if (IS_ERR(spidev_class)) {
 858                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 859                 return PTR_ERR(spidev_class);
 860         }
 861
 862         status = spi_register_driver(&spidev_spi_driver);
 863         if (status < 0) {
 864                 class_destroy(spidev_class);
 865                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 866         }
 867         return status;
 868 }
 869 module_init(spidev_init);
 870
 871 static void __exit spidev_exit(void)
 872 {
 873         spi_unregister_driver(&spidev_spi_driver);
 874         class_destroy(spidev_class);
 875         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 876 }
 877 module_exit(spidev_exit);
 878
 879 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 880 MODULE_DESCRIPTION("User mode SPI device interface");
 881 MODULE_LICENSE("GPL");
 882 MODULE_ALIAS("spi:spidev");