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 <[email protected]>
   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         struct mutex            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_unlocked(struct spi_device *spi, struct spi_message *message)
  94 {
  95         ssize_t status;
  96
  97         status = spi_sync(spi, message);
  98         if (status == 0)
  99                 status = message->actual_length;
 100
 101         return status;
 102 }
 103
 104 static ssize_t
 105 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
 106 {
 107         ssize_t status;
 108         struct spi_device *spi;
 109
 110         mutex_lock(&spidev->spi_lock);
 111         spi = spidev->spi;
 112
 113         if (spi == NULL)
 114                 status = -ESHUTDOWN;
 115         else
 116                 status = spidev_sync_unlocked(spi, message);
 117
 118         mutex_unlock(&spidev->spi_lock);
 119         return status;
 120 }
 121
 122 static inline ssize_t
 123 spidev_sync_write(struct spidev_data *spidev, size_t len)
 124 {
 125         struct spi_transfer     t = {
 126                         .tx_buf         = spidev->tx_buffer,
 127                         .len            = len,
 128                         .speed_hz       = spidev->speed_hz,
 129                 };
 130         struct spi_message      m;
 131
 132         spi_message_init(&m);
 133         spi_message_add_tail(&t, &m);
 134         return spidev_sync(spidev, &m);
 135 }
 136
 137 static inline ssize_t
 138 spidev_sync_read(struct spidev_data *spidev, size_t len)
 139 {
 140         struct spi_transfer     t = {
 141                         .rx_buf         = spidev->rx_buffer,
 142                         .len            = len,
 143                         .speed_hz       = spidev->speed_hz,
 144                 };
 145         struct spi_message      m;
 146
 147         spi_message_init(&m);
 148         spi_message_add_tail(&t, &m);
 149         return spidev_sync(spidev, &m);
 150 }
 151
 152 /*-------------------------------------------------------------------------*/
 153
 154 /* Read-only message with current device setup */
 155 static ssize_t
 156 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 157 {
 158         struct spidev_data      *spidev;
 159         ssize_t                 status;
 160
 161         /* chipselect only toggles at start or end of operation */
 162         if (count > bufsiz)
 163                 return -EMSGSIZE;
 164
 165         spidev = filp->private_data;
 166
 167         mutex_lock(&spidev->buf_lock);
 168         status = spidev_sync_read(spidev, count);
 169         if (status > 0) {
 170                 unsigned long   missing;
 171
 172                 missing = copy_to_user(buf, spidev->rx_buffer, status);
 173                 if (missing == status)
 174                         status = -EFAULT;
 175                 else
 176                         status = status - missing;
 177         }
 178         mutex_unlock(&spidev->buf_lock);
 179
 180         return status;
 181 }
 182
 183 /* Write-only message with current device setup */
 184 static ssize_t
 185 spidev_write(struct file *filp, const char __user *buf,
 186                 size_t count, loff_t *f_pos)
 187 {
 188         struct spidev_data      *spidev;
 189         ssize_t                 status;
 190         unsigned long           missing;
 191
 192         /* chipselect only toggles at start or end of operation */
 193         if (count > bufsiz)
 194                 return -EMSGSIZE;
 195
 196         spidev = filp->private_data;
 197
 198         mutex_lock(&spidev->buf_lock);
 199         missing = copy_from_user(spidev->tx_buffer, buf, count);
 200         if (missing == 0)
 201                 status = spidev_sync_write(spidev, count);
 202         else
 203                 status = -EFAULT;
 204         mutex_unlock(&spidev->buf_lock);
 205
 206         return status;
 207 }
 208
 209 static int spidev_message(struct spidev_data *spidev,
 210                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 211 {
 212         struct spi_message      msg;
 213         struct spi_transfer     *k_xfers;
 214         struct spi_transfer     *k_tmp;
 215         struct spi_ioc_transfer *u_tmp;
 216         unsigned                n, total, tx_total, rx_total;
 217         u8                      *tx_buf, *rx_buf;
 218         int                     status = -EFAULT;
 219
 220         spi_message_init(&msg);
 221         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 222         if (k_xfers == NULL)
 223                 return -ENOMEM;
 224
 225         /* Construct spi_message, copying any tx data to bounce buffer.
 226          * We walk the array of user-provided transfers, using each one
 227          * to initialize a kernel version of the same transfer.
 228          */
 229         tx_buf = spidev->tx_buffer;
 230         rx_buf = spidev->rx_buffer;
 231         total = 0;
 232         tx_total = 0;
 233         rx_total = 0;
 234         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 235                         n;
 236                         n--, k_tmp++, u_tmp++) {
 237                 /* Ensure that also following allocations from rx_buf/tx_buf will meet
 238                  * DMA alignment requirements.
 239                  */
 240                 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN);
 241
 242                 k_tmp->len = u_tmp->len;
 243
 244                 total += k_tmp->len;
 245                 /* Since the function returns the total length of transfers
 246                  * on success, restrict the total to positive int values to
 247                  * avoid the return value looking like an error.  Also check
 248                  * each transfer length to avoid arithmetic overflow.
 249                  */
 250                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 251                         status = -EMSGSIZE;
 252                         goto done;
 253                 }
 254
 255                 if (u_tmp->rx_buf) {
 256                         /* this transfer needs space in RX bounce buffer */
 257                         rx_total += len_aligned;
 258                         if (rx_total > bufsiz) {
 259                                 status = -EMSGSIZE;
 260                                 goto done;
 261                         }
 262                         k_tmp->rx_buf = rx_buf;
 263                         rx_buf += len_aligned;
 264                 }
 265                 if (u_tmp->tx_buf) {
 266                         /* this transfer needs space in TX bounce buffer */
 267                         tx_total += len_aligned;
 268                         if (tx_total > bufsiz) {
 269                                 status = -EMSGSIZE;
 270                                 goto done;
 271                         }
 272                         k_tmp->tx_buf = tx_buf;
 273                         if (copy_from_user(tx_buf, (const u8 __user *)
 274                                                 (uintptr_t) u_tmp->tx_buf,
 275                                         u_tmp->len))
 276                                 goto done;
 277                         tx_buf += len_aligned;
 278                 }
 279
 280                 k_tmp->cs_change = !!u_tmp->cs_change;
 281                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 282                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 283                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 284                 k_tmp->delay.value = u_tmp->delay_usecs;
 285                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 286                 k_tmp->speed_hz = u_tmp->speed_hz;
 287                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 288                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 289                 if (!k_tmp->speed_hz)
 290                         k_tmp->speed_hz = spidev->speed_hz;
 291 #ifdef VERBOSE
 292                 dev_dbg(&spidev->spi->dev,
 293                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 294                         k_tmp->len,
 295                         k_tmp->rx_buf ? "rx " : "",
 296                         k_tmp->tx_buf ? "tx " : "",
 297                         k_tmp->cs_change ? "cs " : "",
 298                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 299                         k_tmp->delay.value,
 300                         k_tmp->word_delay.value,
 301                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 302 #endif
 303                 spi_message_add_tail(k_tmp, &msg);
 304         }
 305
 306         status = spidev_sync_unlocked(spidev->spi, &msg);
 307         if (status < 0)
 308                 goto done;
 309
 310         /* copy any rx data out of bounce buffer */
 311         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 312                         n;
 313                         n--, k_tmp++, u_tmp++) {
 314                 if (u_tmp->rx_buf) {
 315                         if (copy_to_user((u8 __user *)
 316                                         (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
 317                                         u_tmp->len)) {
 318                                 status = -EFAULT;
 319                                 goto done;
 320                         }
 321                 }
 322         }
 323         status = total;
 324
 325 done:
 326         kfree(k_xfers);
 327         return status;
 328 }
 329
 330 static struct spi_ioc_transfer *
 331 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 332                 unsigned *n_ioc)
 333 {
 334         u32     tmp;
 335
 336         /* Check type, command number and direction */
 337         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 338                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 339                         || _IOC_DIR(cmd) != _IOC_WRITE)
 340                 return ERR_PTR(-ENOTTY);
 341
 342         tmp = _IOC_SIZE(cmd);
 343         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 344                 return ERR_PTR(-EINVAL);
 345         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 346         if (*n_ioc == 0)
 347                 return NULL;
 348
 349         /* copy into scratch area */
 350         return memdup_user(u_ioc, tmp);
 351 }
 352
 353 static long
 354 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 355 {
 356         int                     retval = 0;
 357         struct spidev_data      *spidev;
 358         struct spi_device       *spi;
 359         u32                     tmp;
 360         unsigned                n_ioc;
 361         struct spi_ioc_transfer *ioc;
 362
 363         /* Check type and command number */
 364         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 365                 return -ENOTTY;
 366
 367         /* guard against device removal before, or while,
 368          * we issue this ioctl.
 369          */
 370         spidev = filp->private_data;
 371         mutex_lock(&spidev->spi_lock);
 372         spi = spi_dev_get(spidev->spi);
 373         if (spi == NULL) {
 374                 mutex_unlock(&spidev->spi_lock);
 375                 return -ESHUTDOWN;
 376         }
 377
 378         /* use the buffer lock here for triple duty:
 379          *  - prevent I/O (from us) so calling spi_setup() is safe;
 380          *  - prevent concurrent SPI_IOC_WR_* from morphing
 381          *    data fields while SPI_IOC_RD_* reads them;
 382          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 383          */
 384         mutex_lock(&spidev->buf_lock);
 385
 386         switch (cmd) {
 387         /* read requests */
 388         case SPI_IOC_RD_MODE:
 389         case SPI_IOC_RD_MODE32:
 390                 tmp = spi->mode;
 391
 392                 {
 393                         struct spi_controller *ctlr = spi->controller;
 394
 395                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 396                             ctlr->cs_gpiods[spi_get_chipselect(spi, 0)])
 397                                 tmp &= ~SPI_CS_HIGH;
 398                 }
 399
 400                 if (cmd == SPI_IOC_RD_MODE)
 401                         retval = put_user(tmp & SPI_MODE_MASK,
 402                                           (__u8 __user *)arg);
 403                 else
 404                         retval = put_user(tmp & SPI_MODE_MASK,
 405                                           (__u32 __user *)arg);
 406                 break;
 407         case SPI_IOC_RD_LSB_FIRST:
 408                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 409                                         (__u8 __user *)arg);
 410                 break;
 411         case SPI_IOC_RD_BITS_PER_WORD:
 412                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 413                 break;
 414         case SPI_IOC_RD_MAX_SPEED_HZ:
 415                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 416                 break;
 417
 418         /* write requests */
 419         case SPI_IOC_WR_MODE:
 420         case SPI_IOC_WR_MODE32:
 421                 if (cmd == SPI_IOC_WR_MODE)
 422                         retval = get_user(tmp, (u8 __user *)arg);
 423                 else
 424                         retval = get_user(tmp, (u32 __user *)arg);
 425                 if (retval == 0) {
 426                         struct spi_controller *ctlr = spi->controller;
 427                         u32     save = spi->mode;
 428
 429                         if (tmp & ~SPI_MODE_MASK) {
 430                                 retval = -EINVAL;
 431                                 break;
 432                         }
 433
 434                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 435                             ctlr->cs_gpiods[spi_get_chipselect(spi, 0)])
 436                                 tmp |= SPI_CS_HIGH;
 437
 438                         tmp |= spi->mode & ~SPI_MODE_MASK;
 439                         spi->mode = tmp & SPI_MODE_USER_MASK;
 440                         retval = spi_setup(spi);
 441                         if (retval < 0)
 442                                 spi->mode = save;
 443                         else
 444                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 445                 }
 446                 break;
 447         case SPI_IOC_WR_LSB_FIRST:
 448                 retval = get_user(tmp, (__u8 __user *)arg);
 449                 if (retval == 0) {
 450                         u32     save = spi->mode;
 451
 452                         if (tmp)
 453                                 spi->mode |= SPI_LSB_FIRST;
 454                         else
 455                                 spi->mode &= ~SPI_LSB_FIRST;
 456                         retval = spi_setup(spi);
 457                         if (retval < 0)
 458                                 spi->mode = save;
 459                         else
 460                                 dev_dbg(&spi->dev, "%csb first\n",
 461                                                 tmp ? 'l' : 'm');
 462                 }
 463                 break;
 464         case SPI_IOC_WR_BITS_PER_WORD:
 465                 retval = get_user(tmp, (__u8 __user *)arg);
 466                 if (retval == 0) {
 467                         u8      save = spi->bits_per_word;
 468
 469                         spi->bits_per_word = tmp;
 470                         retval = spi_setup(spi);
 471                         if (retval < 0)
 472                                 spi->bits_per_word = save;
 473                         else
 474                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 475                 }
 476                 break;
 477         case SPI_IOC_WR_MAX_SPEED_HZ: {
 478                 u32 save;
 479
 480                 retval = get_user(tmp, (__u32 __user *)arg);
 481                 if (retval)
 482                         break;
 483                 if (tmp == 0) {
 484                         retval = -EINVAL;
 485                         break;
 486                 }
 487
 488                 save = spi->max_speed_hz;
 489
 490                 spi->max_speed_hz = tmp;
 491                 retval = spi_setup(spi);
 492                 if (retval == 0) {
 493                         spidev->speed_hz = tmp;
 494                         dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
 495                 }
 496
 497                 spi->max_speed_hz = save;
 498                 break;
 499         }
 500         default:
 501                 /* segmented and/or full-duplex I/O request */
 502                 /* Check message and copy into scratch area */
 503                 ioc = spidev_get_ioc_message(cmd,
 504                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 505                 if (IS_ERR(ioc)) {
 506                         retval = PTR_ERR(ioc);
 507                         break;
 508                 }
 509                 if (!ioc)
 510                         break;  /* n_ioc is also 0 */
 511
 512                 /* translate to spi_message, execute */
 513                 retval = spidev_message(spidev, ioc, n_ioc);
 514                 kfree(ioc);
 515                 break;
 516         }
 517
 518         mutex_unlock(&spidev->buf_lock);
 519         spi_dev_put(spi);
 520         mutex_unlock(&spidev->spi_lock);
 521         return retval;
 522 }
 523
 524 #ifdef CONFIG_COMPAT
 525 static long
 526 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 527                 unsigned long arg)
 528 {
 529         struct spi_ioc_transfer __user  *u_ioc;
 530         int                             retval = 0;
 531         struct spidev_data              *spidev;
 532         struct spi_device               *spi;
 533         unsigned                        n_ioc, n;
 534         struct spi_ioc_transfer         *ioc;
 535
 536         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 537
 538         /* guard against device removal before, or while,
 539          * we issue this ioctl.
 540          */
 541         spidev = filp->private_data;
 542         mutex_lock(&spidev->spi_lock);
 543         spi = spi_dev_get(spidev->spi);
 544         if (spi == NULL) {
 545                 mutex_unlock(&spidev->spi_lock);
 546                 return -ESHUTDOWN;
 547         }
 548
 549         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 550         mutex_lock(&spidev->buf_lock);
 551
 552         /* Check message and copy into scratch area */
 553         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 554         if (IS_ERR(ioc)) {
 555                 retval = PTR_ERR(ioc);
 556                 goto done;
 557         }
 558         if (!ioc)
 559                 goto done;      /* n_ioc is also 0 */
 560
 561         /* Convert buffer pointers */
 562         for (n = 0; n < n_ioc; n++) {
 563                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 564                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 565         }
 566
 567         /* translate to spi_message, execute */
 568         retval = spidev_message(spidev, ioc, n_ioc);
 569         kfree(ioc);
 570
 571 done:
 572         mutex_unlock(&spidev->buf_lock);
 573         spi_dev_put(spi);
 574         mutex_unlock(&spidev->spi_lock);
 575         return retval;
 576 }
 577
 578 static long
 579 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 580 {
 581         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 582                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 583                         && _IOC_DIR(cmd) == _IOC_WRITE)
 584                 return spidev_compat_ioc_message(filp, cmd, arg);
 585
 586         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 587 }
 588 #else
 589 #define spidev_compat_ioctl NULL
 590 #endif /* CONFIG_COMPAT */
 591
 592 static int spidev_open(struct inode *inode, struct file *filp)
 593 {
 594         struct spidev_data      *spidev = NULL, *iter;
 595         int                     status = -ENXIO;
 596
 597         mutex_lock(&device_list_lock);
 598
 599         list_for_each_entry(iter, &device_list, device_entry) {
 600                 if (iter->devt == inode->i_rdev) {
 601                         status = 0;
 602                         spidev = iter;
 603                         break;
 604                 }
 605         }
 606
 607         if (!spidev) {
 608                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 609                 goto err_find_dev;
 610         }
 611
 612         if (!spidev->tx_buffer) {
 613                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 614                 if (!spidev->tx_buffer) {
 615                         status = -ENOMEM;
 616                         goto err_find_dev;
 617                 }
 618         }
 619
 620         if (!spidev->rx_buffer) {
 621                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 622                 if (!spidev->rx_buffer) {
 623                         status = -ENOMEM;
 624                         goto err_alloc_rx_buf;
 625                 }
 626         }
 627
 628         spidev->users++;
 629         filp->private_data = spidev;
 630         stream_open(inode, filp);
 631
 632         mutex_unlock(&device_list_lock);
 633         return 0;
 634
 635 err_alloc_rx_buf:
 636         kfree(spidev->tx_buffer);
 637         spidev->tx_buffer = NULL;
 638 err_find_dev:
 639         mutex_unlock(&device_list_lock);
 640         return status;
 641 }
 642
 643 static int spidev_release(struct inode *inode, struct file *filp)
 644 {
 645         struct spidev_data      *spidev;
 646         int                     dofree;
 647
 648         mutex_lock(&device_list_lock);
 649         spidev = filp->private_data;
 650         filp->private_data = NULL;
 651
 652         mutex_lock(&spidev->spi_lock);
 653         /* ... after we unbound from the underlying device? */
 654         dofree = (spidev->spi == NULL);
 655         mutex_unlock(&spidev->spi_lock);
 656
 657         /* last close? */
 658         spidev->users--;
 659         if (!spidev->users) {
 660
 661                 kfree(spidev->tx_buffer);
 662                 spidev->tx_buffer = NULL;
 663
 664                 kfree(spidev->rx_buffer);
 665                 spidev->rx_buffer = NULL;
 666
 667                 if (dofree)
 668                         kfree(spidev);
 669                 else
 670                         spidev->speed_hz = spidev->spi->max_speed_hz;
 671         }
 672 #ifdef CONFIG_SPI_SLAVE
 673         if (!dofree)
 674                 spi_slave_abort(spidev->spi);
 675 #endif
 676         mutex_unlock(&device_list_lock);
 677
 678         return 0;
 679 }
 680
 681 static const struct file_operations spidev_fops = {
 682         .owner =        THIS_MODULE,
 683         /* REVISIT switch to aio primitives, so that userspace
 684          * gets more complete API coverage.  It'll simplify things
 685          * too, except for the locking.
 686          */
 687         .write =        spidev_write,
 688         .read =         spidev_read,
 689         .unlocked_ioctl = spidev_ioctl,
 690         .compat_ioctl = spidev_compat_ioctl,
 691         .open =         spidev_open,
 692         .release =      spidev_release,
 693         .llseek =       no_llseek,
 694 };
 695
 696 /*-------------------------------------------------------------------------*/
 697
 698 /* The main reason to have this class is to make mdev/udev create the
 699  * /dev/spidevB.C character device nodes exposing our userspace API.
 700  * It also simplifies memory management.
 701  */
 702
 703 static struct class *spidev_class;
 704
 705 static const struct spi_device_id spidev_spi_ids[] = {
 706         { .name = "dh2228fv" },
 707         { .name = "ltc2488" },
 708         { .name = "sx1301" },
 709         { .name = "bk4" },
 710         { .name = "dhcom-board" },
 711         { .name = "m53cpld" },
 712         { .name = "spi-petra" },
 713         { .name = "spi-authenta" },
 714         { .name = "em3581" },
 715         { .name = "si3210" },
 716         {},
 717 };
 718 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
 719
 720 /*
 721  * spidev should never be referenced in DT without a specific compatible string,
 722  * it is a Linux implementation thing rather than a description of the hardware.
 723  */
 724 static int spidev_of_check(struct device *dev)
 725 {
 726         if (device_property_match_string(dev, "compatible", "spidev") < 0)
 727                 return 0;
 728
 729         dev_err(dev, "spidev listed directly in DT is not supported\n");
 730         return -EINVAL;
 731 }
 732
 733 static const struct of_device_id spidev_dt_ids[] = {
 734         { .compatible = "cisco,spi-petra", .data = &spidev_of_check },
 735         { .compatible = "dh,dhcom-board", .data = &spidev_of_check },
 736         { .compatible = "lineartechnology,ltc2488", .data = &spidev_of_check },
 737         { .compatible = "lwn,bk4", .data = &spidev_of_check },
 738         { .compatible = "menlo,m53cpld", .data = &spidev_of_check },
 739         { .compatible = "micron,spi-authenta", .data = &spidev_of_check },
 740         { .compatible = "rohm,dh2228fv", .data = &spidev_of_check },
 741         { .compatible = "semtech,sx1301", .data = &spidev_of_check },
 742         { .compatible = "silabs,em3581", .data = &spidev_of_check },
 743         { .compatible = "silabs,si3210", .data = &spidev_of_check },
 744         {},
 745 };
 746 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 747
 748 /* Dummy SPI devices not to be used in production systems */
 749 static int spidev_acpi_check(struct device *dev)
 750 {
 751         dev_warn(dev, "do not use this driver in production systems!\n");
 752         return 0;
 753 }
 754
 755 static const struct acpi_device_id spidev_acpi_ids[] = {
 756         /*
 757          * The ACPI SPT000* devices are only meant for development and
 758          * testing. Systems used in production should have a proper ACPI
 759          * description of the connected peripheral and they should also use
 760          * a proper driver instead of poking directly to the SPI bus.
 761          */
 762         { "SPT0001", (kernel_ulong_t)&spidev_acpi_check },
 763         { "SPT0002", (kernel_ulong_t)&spidev_acpi_check },
 764         { "SPT0003", (kernel_ulong_t)&spidev_acpi_check },
 765         {},
 766 };
 767 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 768
 769 /*-------------------------------------------------------------------------*/
 770
 771 static int spidev_probe(struct spi_device *spi)
 772 {
 773         int (*match)(struct device *dev);
 774         struct spidev_data      *spidev;
 775         int                     status;
 776         unsigned long           minor;
 777
 778         match = device_get_match_data(&spi->dev);
 779         if (match) {
 780                 status = match(&spi->dev);
 781                 if (status)
 782                         return status;
 783         }
 784
 785         /* Allocate driver data */
 786         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 787         if (!spidev)
 788                 return -ENOMEM;
 789
 790         /* Initialize the driver data */
 791         spidev->spi = spi;
 792         mutex_init(&spidev->spi_lock);
 793         mutex_init(&spidev->buf_lock);
 794
 795         INIT_LIST_HEAD(&spidev->device_entry);
 796
 797         /* If we can allocate a minor number, hook up this device.
 798          * Reusing minors is fine so long as udev or mdev is working.
 799          */
 800         mutex_lock(&device_list_lock);
 801         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 802         if (minor < N_SPI_MINORS) {
 803                 struct device *dev;
 804
 805                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 806                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 807                                     spidev, "spidev%d.%d",
 808                                     spi->master->bus_num, spi_get_chipselect(spi, 0));
 809                 status = PTR_ERR_OR_ZERO(dev);
 810         } else {
 811                 dev_dbg(&spi->dev, "no minor number available!\n");
 812                 status = -ENODEV;
 813         }
 814         if (status == 0) {
 815                 set_bit(minor, minors);
 816                 list_add(&spidev->device_entry, &device_list);
 817         }
 818         mutex_unlock(&device_list_lock);
 819
 820         spidev->speed_hz = spi->max_speed_hz;
 821
 822         if (status == 0)
 823                 spi_set_drvdata(spi, spidev);
 824         else
 825                 kfree(spidev);
 826
 827         return status;
 828 }
 829
 830 static void spidev_remove(struct spi_device *spi)
 831 {
 832         struct spidev_data      *spidev = spi_get_drvdata(spi);
 833
 834         /* prevent new opens */
 835         mutex_lock(&device_list_lock);
 836         /* make sure ops on existing fds can abort cleanly */
 837         mutex_lock(&spidev->spi_lock);
 838         spidev->spi = NULL;
 839         mutex_unlock(&spidev->spi_lock);
 840
 841         list_del(&spidev->device_entry);
 842         device_destroy(spidev_class, spidev->devt);
 843         clear_bit(MINOR(spidev->devt), minors);
 844         if (spidev->users == 0)
 845                 kfree(spidev);
 846         mutex_unlock(&device_list_lock);
 847 }
 848
 849 static struct spi_driver spidev_spi_driver = {
 850         .driver = {
 851                 .name =         "spidev",
 852                 .of_match_table = spidev_dt_ids,
 853                 .acpi_match_table = spidev_acpi_ids,
 854         },
 855         .probe =        spidev_probe,
 856         .remove =       spidev_remove,
 857         .id_table =     spidev_spi_ids,
 858
 859         /* NOTE:  suspend/resume methods are not necessary here.
 860          * We don't do anything except pass the requests to/from
 861          * the underlying controller.  The refrigerator handles
 862          * most issues; the controller driver handles the rest.
 863          */
 864 };
 865
 866 /*-------------------------------------------------------------------------*/
 867
 868 static int __init spidev_init(void)
 869 {
 870         int status;
 871
 872         /* Claim our 256 reserved device numbers.  Then register a class
 873          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 874          * the driver which manages those device numbers.
 875          */
 876         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 877         if (status < 0)
 878                 return status;
 879
 880         spidev_class = class_create("spidev");
 881         if (IS_ERR(spidev_class)) {
 882                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 883                 return PTR_ERR(spidev_class);
 884         }
 885
 886         status = spi_register_driver(&spidev_spi_driver);
 887         if (status < 0) {
 888                 class_destroy(spidev_class);
 889                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 890         }
 891         return status;
 892 }
 893 module_init(spidev_init);
 894
 895 static void __exit spidev_exit(void)
 896 {
 897         spi_unregister_driver(&spidev_spi_driver);
 898         class_destroy(spidev_class);
 899         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 900 }
 901 module_exit(spidev_exit);
 902
 903 MODULE_AUTHOR("Andrea Paterniani, <[email protected]>");
 904 MODULE_DESCRIPTION("User mode SPI device interface");
 905 MODULE_LICENSE("GPL");
 906 MODULE_ALIAS("spi:spidev");