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         case SPI_IOC_RD_MODE32:
 381                 tmp = spi->mode;
 382
 383                 {
 384                         struct spi_controller *ctlr = spi->controller;
 385
 386                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 387                             ctlr->cs_gpiods[spi->chip_select])
 388                                 tmp &= ~SPI_CS_HIGH;
 389                 }
 390
 391                 if (cmd == SPI_IOC_RD_MODE)
 392                         retval = put_user(tmp & SPI_MODE_MASK,
 393                                           (__u8 __user *)arg);
 394                 else
 395                         retval = put_user(tmp & SPI_MODE_MASK,
 396                                           (__u32 __user *)arg);
 397                 break;
 398         case SPI_IOC_RD_LSB_FIRST:
 399                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 400                                         (__u8 __user *)arg);
 401                 break;
 402         case SPI_IOC_RD_BITS_PER_WORD:
 403                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 404                 break;
 405         case SPI_IOC_RD_MAX_SPEED_HZ:
 406                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 407                 break;
 408
 409         /* write requests */
 410         case SPI_IOC_WR_MODE:
 411         case SPI_IOC_WR_MODE32:
 412                 if (cmd == SPI_IOC_WR_MODE)
 413                         retval = get_user(tmp, (u8 __user *)arg);
 414                 else
 415                         retval = get_user(tmp, (u32 __user *)arg);
 416                 if (retval == 0) {
 417                         struct spi_controller *ctlr = spi->controller;
 418                         u32     save = spi->mode;
 419
 420                         if (tmp & ~SPI_MODE_MASK) {
 421                                 retval = -EINVAL;
 422                                 break;
 423                         }
 424
 425                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 426                             ctlr->cs_gpiods[spi->chip_select])
 427                                 tmp |= SPI_CS_HIGH;
 428
 429                         tmp |= spi->mode & ~SPI_MODE_MASK;
 430                         spi->mode = tmp & SPI_MODE_USER_MASK;
 431                         retval = spi_setup(spi);
 432                         if (retval < 0)
 433                                 spi->mode = save;
 434                         else
 435                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 436                 }
 437                 break;
 438         case SPI_IOC_WR_LSB_FIRST:
 439                 retval = get_user(tmp, (__u8 __user *)arg);
 440                 if (retval == 0) {
 441                         u32     save = spi->mode;
 442
 443                         if (tmp)
 444                                 spi->mode |= SPI_LSB_FIRST;
 445                         else
 446                                 spi->mode &= ~SPI_LSB_FIRST;
 447                         retval = spi_setup(spi);
 448                         if (retval < 0)
 449                                 spi->mode = save;
 450                         else
 451                                 dev_dbg(&spi->dev, "%csb first\n",
 452                                                 tmp ? 'l' : 'm');
 453                 }
 454                 break;
 455         case SPI_IOC_WR_BITS_PER_WORD:
 456                 retval = get_user(tmp, (__u8 __user *)arg);
 457                 if (retval == 0) {
 458                         u8      save = spi->bits_per_word;
 459
 460                         spi->bits_per_word = tmp;
 461                         retval = spi_setup(spi);
 462                         if (retval < 0)
 463                                 spi->bits_per_word = save;
 464                         else
 465                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 466                 }
 467                 break;
 468         case SPI_IOC_WR_MAX_SPEED_HZ: {
 469                 u32 save;
 470
 471                 retval = get_user(tmp, (__u32 __user *)arg);
 472                 if (retval)
 473                         break;
 474                 if (tmp == 0) {
 475                         retval = -EINVAL;
 476                         break;
 477                 }
 478
 479                 save = spi->max_speed_hz;
 480
 481                 spi->max_speed_hz = tmp;
 482                 retval = spi_setup(spi);
 483                 if (retval == 0) {
 484                         spidev->speed_hz = tmp;
 485                         dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
 486                 }
 487
 488                 spi->max_speed_hz = save;
 489                 break;
 490         }
 491         default:
 492                 /* segmented and/or full-duplex I/O request */
 493                 /* Check message and copy into scratch area */
 494                 ioc = spidev_get_ioc_message(cmd,
 495                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 496                 if (IS_ERR(ioc)) {
 497                         retval = PTR_ERR(ioc);
 498                         break;
 499                 }
 500                 if (!ioc)
 501                         break;  /* n_ioc is also 0 */
 502
 503                 /* translate to spi_message, execute */
 504                 retval = spidev_message(spidev, ioc, n_ioc);
 505                 kfree(ioc);
 506                 break;
 507         }
 508
 509         mutex_unlock(&spidev->buf_lock);
 510         spi_dev_put(spi);
 511         return retval;
 512 }
 513
 514 #ifdef CONFIG_COMPAT
 515 static long
 516 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 517                 unsigned long arg)
 518 {
 519         struct spi_ioc_transfer __user  *u_ioc;
 520         int                             retval = 0;
 521         struct spidev_data              *spidev;
 522         struct spi_device               *spi;
 523         unsigned                        n_ioc, n;
 524         struct spi_ioc_transfer         *ioc;
 525
 526         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 527
 528         /* guard against device removal before, or while,
 529          * we issue this ioctl.
 530          */
 531         spidev = filp->private_data;
 532         spin_lock_irq(&spidev->spi_lock);
 533         spi = spi_dev_get(spidev->spi);
 534         spin_unlock_irq(&spidev->spi_lock);
 535
 536         if (spi == NULL)
 537                 return -ESHUTDOWN;
 538
 539         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 540         mutex_lock(&spidev->buf_lock);
 541
 542         /* Check message and copy into scratch area */
 543         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 544         if (IS_ERR(ioc)) {
 545                 retval = PTR_ERR(ioc);
 546                 goto done;
 547         }
 548         if (!ioc)
 549                 goto done;      /* n_ioc is also 0 */
 550
 551         /* Convert buffer pointers */
 552         for (n = 0; n < n_ioc; n++) {
 553                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 554                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 555         }
 556
 557         /* translate to spi_message, execute */
 558         retval = spidev_message(spidev, ioc, n_ioc);
 559         kfree(ioc);
 560
 561 done:
 562         mutex_unlock(&spidev->buf_lock);
 563         spi_dev_put(spi);
 564         return retval;
 565 }
 566
 567 static long
 568 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 569 {
 570         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 571                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 572                         && _IOC_DIR(cmd) == _IOC_WRITE)
 573                 return spidev_compat_ioc_message(filp, cmd, arg);
 574
 575         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 576 }
 577 #else
 578 #define spidev_compat_ioctl NULL
 579 #endif /* CONFIG_COMPAT */
 580
 581 static int spidev_open(struct inode *inode, struct file *filp)
 582 {
 583         struct spidev_data      *spidev = NULL, *iter;
 584         int                     status = -ENXIO;
 585
 586         mutex_lock(&device_list_lock);
 587
 588         list_for_each_entry(iter, &device_list, device_entry) {
 589                 if (iter->devt == inode->i_rdev) {
 590                         status = 0;
 591                         spidev = iter;
 592                         break;
 593                 }
 594         }
 595
 596         if (!spidev) {
 597                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 598                 goto err_find_dev;
 599         }
 600
 601         if (!spidev->tx_buffer) {
 602                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 603                 if (!spidev->tx_buffer) {
 604                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 605                         status = -ENOMEM;
 606                         goto err_find_dev;
 607                 }
 608         }
 609
 610         if (!spidev->rx_buffer) {
 611                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 612                 if (!spidev->rx_buffer) {
 613                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 614                         status = -ENOMEM;
 615                         goto err_alloc_rx_buf;
 616                 }
 617         }
 618
 619         spidev->users++;
 620         filp->private_data = spidev;
 621         stream_open(inode, filp);
 622
 623         mutex_unlock(&device_list_lock);
 624         return 0;
 625
 626 err_alloc_rx_buf:
 627         kfree(spidev->tx_buffer);
 628         spidev->tx_buffer = NULL;
 629 err_find_dev:
 630         mutex_unlock(&device_list_lock);
 631         return status;
 632 }
 633
 634 static int spidev_release(struct inode *inode, struct file *filp)
 635 {
 636         struct spidev_data      *spidev;
 637         int                     dofree;
 638
 639         mutex_lock(&device_list_lock);
 640         spidev = filp->private_data;
 641         filp->private_data = NULL;
 642
 643         spin_lock_irq(&spidev->spi_lock);
 644         /* ... after we unbound from the underlying device? */
 645         dofree = (spidev->spi == NULL);
 646         spin_unlock_irq(&spidev->spi_lock);
 647
 648         /* last close? */
 649         spidev->users--;
 650         if (!spidev->users) {
 651
 652                 kfree(spidev->tx_buffer);
 653                 spidev->tx_buffer = NULL;
 654
 655                 kfree(spidev->rx_buffer);
 656                 spidev->rx_buffer = NULL;
 657
 658                 if (dofree)
 659                         kfree(spidev);
 660                 else
 661                         spidev->speed_hz = spidev->spi->max_speed_hz;
 662         }
 663 #ifdef CONFIG_SPI_SLAVE
 664         if (!dofree)
 665                 spi_slave_abort(spidev->spi);
 666 #endif
 667         mutex_unlock(&device_list_lock);
 668
 669         return 0;
 670 }
 671
 672 static const struct file_operations spidev_fops = {
 673         .owner =        THIS_MODULE,
 674         /* REVISIT switch to aio primitives, so that userspace
 675          * gets more complete API coverage.  It'll simplify things
 676          * too, except for the locking.
 677          */
 678         .write =        spidev_write,
 679         .read =         spidev_read,
 680         .unlocked_ioctl = spidev_ioctl,
 681         .compat_ioctl = spidev_compat_ioctl,
 682         .open =         spidev_open,
 683         .release =      spidev_release,
 684         .llseek =       no_llseek,
 685 };
 686
 687 /*-------------------------------------------------------------------------*/
 688
 689 /* The main reason to have this class is to make mdev/udev create the
 690  * /dev/spidevB.C character device nodes exposing our userspace API.
 691  * It also simplifies memory management.
 692  */
 693
 694 static struct class *spidev_class;
 695
 696 static const struct spi_device_id spidev_spi_ids[] = {
 697         { .name = "dh2228fv" },
 698         { .name = "ltc2488" },
 699         { .name = "sx1301" },
 700         { .name = "bk4" },
 701         { .name = "dhcom-board" },
 702         { .name = "m53cpld" },
 703         { .name = "spi-petra" },
 704         { .name = "spi-authenta" },
 705         {},
 706 };
 707 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
 708
 709 /*
 710  * spidev should never be referenced in DT without a specific compatible string,
 711  * it is a Linux implementation thing rather than a description of the hardware.
 712  */
 713 static int spidev_of_check(struct device *dev)
 714 {
 715         if (device_property_match_string(dev, "compatible", "spidev") < 0)
 716                 return 0;
 717
 718         dev_err(dev, "spidev listed directly in DT is not supported\n");
 719         return -EINVAL;
 720 }
 721
 722 static const struct of_device_id spidev_dt_ids[] = {
 723         { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
 724         { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
 725         { .compatible = "semtech,sx1301", .data = &spidev_of_check },
 726         { .compatible = "lwn,bk4", .data = &spidev_of_check },
 727         { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
 728         { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
 729         { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
 730         { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
 731         {},
 732 };
 733 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 734
 735 /* Dummy SPI devices not to be used in production systems */
 736 static int spidev_acpi_check(struct device *dev)
 737 {
 738         dev_warn(dev, "do not use this driver in production systems!\n");
 739         return 0;
 740 }
 741
 742 static const struct acpi_device_id spidev_acpi_ids[] = {
 743         /*
 744          * The ACPI SPT000* devices are only meant for development and
 745          * testing. Systems used in production should have a proper ACPI
 746          * description of the connected peripheral and they should also use
 747          * a proper driver instead of poking directly to the SPI bus.
 748          */
 749         { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
 750         { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
 751         { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
 752         {},
 753 };
 754 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 755
 756 /*-------------------------------------------------------------------------*/
 757
 758 static int spidev_probe(struct spi_device *spi)
 759 {
 760         int (*match)(struct device *dev);
 761         struct spidev_data      *spidev;
 762         int                     status;
 763         unsigned long           minor;
 764
 765         match = device_get_match_data(&spi->dev);
 766         if (match) {
 767                 status = match(&spi->dev);
 768                 if (status)
 769                         return status;
 770         }
 771
 772         /* Allocate driver data */
 773         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 774         if (!spidev)
 775                 return -ENOMEM;
 776
 777         /* Initialize the driver data */
 778         spidev->spi = spi;
 779         spin_lock_init(&spidev->spi_lock);
 780         mutex_init(&spidev->buf_lock);
 781
 782         INIT_LIST_HEAD(&spidev->device_entry);
 783
 784         /* If we can allocate a minor number, hook up this device.
 785          * Reusing minors is fine so long as udev or mdev is working.
 786          */
 787         mutex_lock(&device_list_lock);
 788         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 789         if (minor < N_SPI_MINORS) {
 790                 struct device *dev;
 791
 792                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 793                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 794                                     spidev, "spidev%d.%d",
 795                                     spi->master->bus_num, spi->chip_select);
 796                 status = PTR_ERR_OR_ZERO(dev);
 797         } else {
 798                 dev_dbg(&spi->dev, "no minor number available!\n");
 799                 status = -ENODEV;
 800         }
 801         if (status == 0) {
 802                 set_bit(minor, minors);
 803                 list_add(&spidev->device_entry, &device_list);
 804         }
 805         mutex_unlock(&device_list_lock);
 806
 807         spidev->speed_hz = spi->max_speed_hz;
 808
 809         if (status == 0)
 810                 spi_set_drvdata(spi, spidev);
 811         else
 812                 kfree(spidev);
 813
 814         return status;
 815 }
 816
 817 static void spidev_remove(struct spi_device *spi)
 818 {
 819         struct spidev_data      *spidev = spi_get_drvdata(spi);
 820
 821         /* prevent new opens */
 822         mutex_lock(&device_list_lock);
 823         /* make sure ops on existing fds can abort cleanly */
 824         spin_lock_irq(&spidev->spi_lock);
 825         spidev->spi = NULL;
 826         spin_unlock_irq(&spidev->spi_lock);
 827
 828         list_del(&spidev->device_entry);
 829         device_destroy(spidev_class, spidev->devt);
 830         clear_bit(MINOR(spidev->devt), minors);
 831         if (spidev->users == 0)
 832                 kfree(spidev);
 833         mutex_unlock(&device_list_lock);
 834 }
 835
 836 static struct spi_driver spidev_spi_driver = {
 837         .driver = {
 838                 .name =         "spidev",
 839                 .of_match_table = spidev_dt_ids,
 840                 .acpi_match_table = spidev_acpi_ids,
 841         },
 842         .probe =        spidev_probe,
 843         .remove =       spidev_remove,
 844         .id_table =     spidev_spi_ids,
 845
 846         /* NOTE:  suspend/resume methods are not necessary here.
 847          * We don't do anything except pass the requests to/from
 848          * the underlying controller.  The refrigerator handles
 849          * most issues; the controller driver handles the rest.
 850          */
 851 };
 852
 853 /*-------------------------------------------------------------------------*/
 854
 855 static int __init spidev_init(void)
 856 {
 857         int status;
 858
 859         /* Claim our 256 reserved device numbers.  Then register a class
 860          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 861          * the driver which manages those device numbers.
 862          */
 863         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 864         if (status < 0)
 865                 return status;
 866
 867         spidev_class = class_create(THIS_MODULE, "spidev");
 868         if (IS_ERR(spidev_class)) {
 869                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 870                 return PTR_ERR(spidev_class);
 871         }
 872
 873         status = spi_register_driver(&spidev_spi_driver);
 874         if (status < 0) {
 875                 class_destroy(spidev_class);
 876                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 877         }
 878         return status;
 879 }
 880 module_init(spidev_init);
 881
 882 static void __exit spidev_exit(void)
 883 {
 884         spi_unregister_driver(&spidev_spi_driver);
 885         class_destroy(spidev_class);
 886         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 887 }
 888 module_exit(spidev_exit);
 889
 890 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 891 MODULE_DESCRIPTION("User mode SPI device interface");
 892 MODULE_LICENSE("GPL");
 893 MODULE_ALIAS("spi:spidev");