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/module.h>
  12 #include <linux/ioctl.h>
  13 #include <linux/fs.h>
  14 #include <linux/device.h>
  15 #include <linux/err.h>
  16 #include <linux/list.h>
  17 #include <linux/errno.h>
  18 #include <linux/mutex.h>
  19 #include <linux/slab.h>
  20 #include <linux/compat.h>
  21 #include <linux/of.h>
  22 #include <linux/of_device.h>
  23 #include <linux/acpi.h>
  24
  25 #include <linux/spi/spi.h>
  26 #include <linux/spi/spidev.h>
  27
  28 #include <linux/uaccess.h>
  29
  30
  31 /*
  32  * This supports access to SPI devices using normal userspace I/O calls.
  33  * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
  34  * and often mask message boundaries, full SPI support requires full duplex
  35  * transfers.  There are several kinds of internal message boundaries to
  36  * handle chipselect management and other protocol options.
  37  *
  38  * SPI has a character major number assigned.  We allocate minor numbers
  39  * dynamically using a bitmask.  You must use hotplug tools, such as udev
  40  * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
  41  * nodes, since there is no fixed association of minor numbers with any
  42  * particular SPI bus or device.
  43  */
  44 #define SPIDEV_MAJOR                    153     /* assigned */
  45 #define N_SPI_MINORS                    32      /* ... up to 256 */
  46
  47 static DECLARE_BITMAP(minors, N_SPI_MINORS);
  48
  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
  68 struct spidev_data {
  69         dev_t                   devt;
  70         spinlock_t              spi_lock;
  71         struct spi_device       *spi;
  72         struct list_head        device_entry;
  73
  74         /* TX/RX buffers are NULL unless this device is open (users > 0) */
  75         struct mutex            buf_lock;
  76         unsigned                users;
  77         u8                      *tx_buffer;
  78         u8                      *rx_buffer;
  79         u32                     speed_hz;
  80 };
  81
  82 static LIST_HEAD(device_list);
  83 static DEFINE_MUTEX(device_list_lock);
  84
  85 static unsigned bufsiz = 4096;
  86 module_param(bufsiz, uint, S_IRUGO);
  87 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  88
  89 /*-------------------------------------------------------------------------*/
  90
  91 static ssize_t
  92 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
  93 {
  94         int status;
  95         struct spi_device *spi;
  96
  97         spin_lock_irq(&spidev->spi_lock);
  98         spi = spidev->spi;
  99         spin_unlock_irq(&spidev->spi_lock);
 100
 101         if (spi == NULL)
 102                 status = -ESHUTDOWN;
 103         else
 104                 status = spi_sync(spi, message);
 105
 106         if (status == 0)
 107                 status = message->actual_length;
 108
 109         return status;
 110 }
 111
 112 static inline ssize_t
 113 spidev_sync_write(struct spidev_data *spidev, size_t len)
 114 {
 115         struct spi_transfer     t = {
 116                         .tx_buf         = spidev->tx_buffer,
 117                         .len            = len,
 118                         .speed_hz       = spidev->speed_hz,
 119                 };
 120         struct spi_message      m;
 121
 122         spi_message_init(&m);
 123         spi_message_add_tail(&t, &m);
 124         return spidev_sync(spidev, &m);
 125 }
 126
 127 static inline ssize_t
 128 spidev_sync_read(struct spidev_data *spidev, size_t len)
 129 {
 130         struct spi_transfer     t = {
 131                         .rx_buf         = spidev->rx_buffer,
 132                         .len            = len,
 133                         .speed_hz       = spidev->speed_hz,
 134                 };
 135         struct spi_message      m;
 136
 137         spi_message_init(&m);
 138         spi_message_add_tail(&t, &m);
 139         return spidev_sync(spidev, &m);
 140 }
 141
 142 /*-------------------------------------------------------------------------*/
 143
 144 /* Read-only message with current device setup */
 145 static ssize_t
 146 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 147 {
 148         struct spidev_data      *spidev;
 149         ssize_t                 status;
 150
 151         /* chipselect only toggles at start or end of operation */
 152         if (count > bufsiz)
 153                 return -EMSGSIZE;
 154
 155         spidev = filp->private_data;
 156
 157         mutex_lock(&spidev->buf_lock);
 158         status = spidev_sync_read(spidev, count);
 159         if (status > 0) {
 160                 unsigned long   missing;
 161
 162                 missing = copy_to_user(buf, spidev->rx_buffer, status);
 163                 if (missing == status)
 164                         status = -EFAULT;
 165                 else
 166                         status = status - missing;
 167         }
 168         mutex_unlock(&spidev->buf_lock);
 169
 170         return status;
 171 }
 172
 173 /* Write-only message with current device setup */
 174 static ssize_t
 175 spidev_write(struct file *filp, const char __user *buf,
 176                 size_t count, loff_t *f_pos)
 177 {
 178         struct spidev_data      *spidev;
 179         ssize_t                 status;
 180         unsigned long           missing;
 181
 182         /* chipselect only toggles at start or end of operation */
 183         if (count > bufsiz)
 184                 return -EMSGSIZE;
 185
 186         spidev = filp->private_data;
 187
 188         mutex_lock(&spidev->buf_lock);
 189         missing = copy_from_user(spidev->tx_buffer, buf, count);
 190         if (missing == 0)
 191                 status = spidev_sync_write(spidev, count);
 192         else
 193                 status = -EFAULT;
 194         mutex_unlock(&spidev->buf_lock);
 195
 196         return status;
 197 }
 198
 199 static int spidev_message(struct spidev_data *spidev,
 200                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 201 {
 202         struct spi_message      msg;
 203         struct spi_transfer     *k_xfers;
 204         struct spi_transfer     *k_tmp;
 205         struct spi_ioc_transfer *u_tmp;
 206         unsigned                n, total, tx_total, rx_total;
 207         u8                      *tx_buf, *rx_buf;
 208         int                     status = -EFAULT;
 209
 210         spi_message_init(&msg);
 211         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 212         if (k_xfers == NULL)
 213                 return -ENOMEM;
 214
 215         /* Construct spi_message, copying any tx data to bounce buffer.
 216          * We walk the array of user-provided transfers, using each one
 217          * to initialize a kernel version of the same transfer.
 218          */
 219         tx_buf = spidev->tx_buffer;
 220         rx_buf = spidev->rx_buffer;
 221         total = 0;
 222         tx_total = 0;
 223         rx_total = 0;
 224         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 225                         n;
 226                         n--, k_tmp++, u_tmp++) {
 227                 /* Ensure that also following allocations from rx_buf/tx_buf will meet
 228                  * DMA alignment requirements.
 229                  */
 230                 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN);
 231
 232                 k_tmp->len = u_tmp->len;
 233
 234                 total += k_tmp->len;
 235                 /* Since the function returns the total length of transfers
 236                  * on success, restrict the total to positive int values to
 237                  * avoid the return value looking like an error.  Also check
 238                  * each transfer length to avoid arithmetic overflow.
 239                  */
 240                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 241                         status = -EMSGSIZE;
 242                         goto done;
 243                 }
 244
 245                 if (u_tmp->rx_buf) {
 246                         /* this transfer needs space in RX bounce buffer */
 247                         rx_total += len_aligned;
 248                         if (rx_total > bufsiz) {
 249                                 status = -EMSGSIZE;
 250                                 goto done;
 251                         }
 252                         k_tmp->rx_buf = rx_buf;
 253                         rx_buf += len_aligned;
 254                 }
 255                 if (u_tmp->tx_buf) {
 256                         /* this transfer needs space in TX bounce buffer */
 257                         tx_total += len_aligned;
 258                         if (tx_total > bufsiz) {
 259                                 status = -EMSGSIZE;
 260                                 goto done;
 261                         }
 262                         k_tmp->tx_buf = tx_buf;
 263                         if (copy_from_user(tx_buf, (const u8 __user *)
 264                                                 (uintptr_t) u_tmp->tx_buf,
 265                                         u_tmp->len))
 266                                 goto done;
 267                         tx_buf += len_aligned;
 268                 }
 269
 270                 k_tmp->cs_change = !!u_tmp->cs_change;
 271                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 272                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 273                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 274                 k_tmp->delay.value = u_tmp->delay_usecs;
 275                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 276                 k_tmp->speed_hz = u_tmp->speed_hz;
 277                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 278                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 279                 if (!k_tmp->speed_hz)
 280                         k_tmp->speed_hz = spidev->speed_hz;
 281 #ifdef VERBOSE
 282                 dev_dbg(&spidev->spi->dev,
 283                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 284                         k_tmp->len,
 285                         k_tmp->rx_buf ? "rx " : "",
 286                         k_tmp->tx_buf ? "tx " : "",
 287                         k_tmp->cs_change ? "cs " : "",
 288                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 289                         k_tmp->delay.value,
 290                         k_tmp->word_delay.value,
 291                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 292 #endif
 293                 spi_message_add_tail(k_tmp, &msg);
 294         }
 295
 296         status = spidev_sync(spidev, &msg);
 297         if (status < 0)
 298                 goto done;
 299
 300         /* copy any rx data out of bounce buffer */
 301         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 302                         n;
 303                         n--, k_tmp++, u_tmp++) {
 304                 if (u_tmp->rx_buf) {
 305                         if (copy_to_user((u8 __user *)
 306                                         (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
 307                                         u_tmp->len)) {
 308                                 status = -EFAULT;
 309                                 goto done;
 310                         }
 311                 }
 312         }
 313         status = total;
 314
 315 done:
 316         kfree(k_xfers);
 317         return status;
 318 }
 319
 320 static struct spi_ioc_transfer *
 321 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 322                 unsigned *n_ioc)
 323 {
 324         u32     tmp;
 325
 326         /* Check type, command number and direction */
 327         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 328                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 329                         || _IOC_DIR(cmd) != _IOC_WRITE)
 330                 return ERR_PTR(-ENOTTY);
 331
 332         tmp = _IOC_SIZE(cmd);
 333         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 334                 return ERR_PTR(-EINVAL);
 335         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 336         if (*n_ioc == 0)
 337                 return NULL;
 338
 339         /* copy into scratch area */
 340         return memdup_user(u_ioc, tmp);
 341 }
 342
 343 static long
 344 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 345 {
 346         int                     retval = 0;
 347         struct spidev_data      *spidev;
 348         struct spi_device       *spi;
 349         u32                     tmp;
 350         unsigned                n_ioc;
 351         struct spi_ioc_transfer *ioc;
 352
 353         /* Check type and command number */
 354         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 355                 return -ENOTTY;
 356
 357         /* guard against device removal before, or while,
 358          * we issue this ioctl.
 359          */
 360         spidev = filp->private_data;
 361         spin_lock_irq(&spidev->spi_lock);
 362         spi = spi_dev_get(spidev->spi);
 363         spin_unlock_irq(&spidev->spi_lock);
 364
 365         if (spi == NULL)
 366                 return -ESHUTDOWN;
 367
 368         /* use the buffer lock here for triple duty:
 369          *  - prevent I/O (from us) so calling spi_setup() is safe;
 370          *  - prevent concurrent SPI_IOC_WR_* from morphing
 371          *    data fields while SPI_IOC_RD_* reads them;
 372          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 373          */
 374         mutex_lock(&spidev->buf_lock);
 375
 376         switch (cmd) {
 377         /* read requests */
 378         case SPI_IOC_RD_MODE:
 379                 retval = put_user(spi->mode & SPI_MODE_MASK,
 380                                         (__u8 __user *)arg);
 381                 break;
 382         case SPI_IOC_RD_MODE32:
 383                 retval = put_user(spi->mode & SPI_MODE_MASK,
 384                                         (__u32 __user *)arg);
 385                 break;
 386         case SPI_IOC_RD_LSB_FIRST:
 387                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 388                                         (__u8 __user *)arg);
 389                 break;
 390         case SPI_IOC_RD_BITS_PER_WORD:
 391                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 392                 break;
 393         case SPI_IOC_RD_MAX_SPEED_HZ:
 394                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 395                 break;
 396
 397         /* write requests */
 398         case SPI_IOC_WR_MODE:
 399         case SPI_IOC_WR_MODE32:
 400                 if (cmd == SPI_IOC_WR_MODE)
 401                         retval = get_user(tmp, (u8 __user *)arg);
 402                 else
 403                         retval = get_user(tmp, (u32 __user *)arg);
 404                 if (retval == 0) {
 405                         struct spi_controller *ctlr = spi->controller;
 406                         u32     save = spi->mode;
 407
 408                         if (tmp & ~SPI_MODE_MASK) {
 409                                 retval = -EINVAL;
 410                                 break;
 411                         }
 412
 413                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 414                             ctlr->cs_gpiods[spi->chip_select])
 415                                 tmp |= SPI_CS_HIGH;
 416
 417                         tmp |= spi->mode & ~SPI_MODE_MASK;
 418                         spi->mode = (u16)tmp;
 419                         retval = spi_setup(spi);
 420                         if (retval < 0)
 421                                 spi->mode = save;
 422                         else
 423                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 424                 }
 425                 break;
 426         case SPI_IOC_WR_LSB_FIRST:
 427                 retval = get_user(tmp, (__u8 __user *)arg);
 428                 if (retval == 0) {
 429                         u32     save = spi->mode;
 430
 431                         if (tmp)
 432                                 spi->mode |= SPI_LSB_FIRST;
 433                         else
 434                                 spi->mode &= ~SPI_LSB_FIRST;
 435                         retval = spi_setup(spi);
 436                         if (retval < 0)
 437                                 spi->mode = save;
 438                         else
 439                                 dev_dbg(&spi->dev, "%csb first\n",
 440                                                 tmp ? 'l' : 'm');
 441                 }
 442                 break;
 443         case SPI_IOC_WR_BITS_PER_WORD:
 444                 retval = get_user(tmp, (__u8 __user *)arg);
 445                 if (retval == 0) {
 446                         u8      save = spi->bits_per_word;
 447
 448                         spi->bits_per_word = tmp;
 449                         retval = spi_setup(spi);
 450                         if (retval < 0)
 451                                 spi->bits_per_word = save;
 452                         else
 453                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 454                 }
 455                 break;
 456         case SPI_IOC_WR_MAX_SPEED_HZ:
 457                 retval = get_user(tmp, (__u32 __user *)arg);
 458                 if (retval == 0) {
 459                         u32     save = spi->max_speed_hz;
 460
 461                         spi->max_speed_hz = tmp;
 462                         retval = spi_setup(spi);
 463                         if (retval == 0) {
 464                                 spidev->speed_hz = tmp;
 465                                 dev_dbg(&spi->dev, "%d Hz (max)\n",
 466                                         spidev->speed_hz);
 467                         }
 468                         spi->max_speed_hz = save;
 469                 }
 470                 break;
 471
 472         default:
 473                 /* segmented and/or full-duplex I/O request */
 474                 /* Check message and copy into scratch area */
 475                 ioc = spidev_get_ioc_message(cmd,
 476                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 477                 if (IS_ERR(ioc)) {
 478                         retval = PTR_ERR(ioc);
 479                         break;
 480                 }
 481                 if (!ioc)
 482                         break;  /* n_ioc is also 0 */
 483
 484                 /* translate to spi_message, execute */
 485                 retval = spidev_message(spidev, ioc, n_ioc);
 486                 kfree(ioc);
 487                 break;
 488         }
 489
 490         mutex_unlock(&spidev->buf_lock);
 491         spi_dev_put(spi);
 492         return retval;
 493 }
 494
 495 #ifdef CONFIG_COMPAT
 496 static long
 497 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 498                 unsigned long arg)
 499 {
 500         struct spi_ioc_transfer __user  *u_ioc;
 501         int                             retval = 0;
 502         struct spidev_data              *spidev;
 503         struct spi_device               *spi;
 504         unsigned                        n_ioc, n;
 505         struct spi_ioc_transfer         *ioc;
 506
 507         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 508
 509         /* guard against device removal before, or while,
 510          * we issue this ioctl.
 511          */
 512         spidev = filp->private_data;
 513         spin_lock_irq(&spidev->spi_lock);
 514         spi = spi_dev_get(spidev->spi);
 515         spin_unlock_irq(&spidev->spi_lock);
 516
 517         if (spi == NULL)
 518                 return -ESHUTDOWN;
 519
 520         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 521         mutex_lock(&spidev->buf_lock);
 522
 523         /* Check message and copy into scratch area */
 524         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 525         if (IS_ERR(ioc)) {
 526                 retval = PTR_ERR(ioc);
 527                 goto done;
 528         }
 529         if (!ioc)
 530                 goto done;      /* n_ioc is also 0 */
 531
 532         /* Convert buffer pointers */
 533         for (n = 0; n < n_ioc; n++) {
 534                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 535                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 536         }
 537
 538         /* translate to spi_message, execute */
 539         retval = spidev_message(spidev, ioc, n_ioc);
 540         kfree(ioc);
 541
 542 done:
 543         mutex_unlock(&spidev->buf_lock);
 544         spi_dev_put(spi);
 545         return retval;
 546 }
 547
 548 static long
 549 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 550 {
 551         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 552                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 553                         && _IOC_DIR(cmd) == _IOC_WRITE)
 554                 return spidev_compat_ioc_message(filp, cmd, arg);
 555
 556         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 557 }
 558 #else
 559 #define spidev_compat_ioctl NULL
 560 #endif /* CONFIG_COMPAT */
 561
 562 static int spidev_open(struct inode *inode, struct file *filp)
 563 {
 564         struct spidev_data      *spidev;
 565         int                     status = -ENXIO;
 566
 567         mutex_lock(&device_list_lock);
 568
 569         list_for_each_entry(spidev, &device_list, device_entry) {
 570                 if (spidev->devt == inode->i_rdev) {
 571                         status = 0;
 572                         break;
 573                 }
 574         }
 575
 576         if (status) {
 577                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 578                 goto err_find_dev;
 579         }
 580
 581         if (!spidev->tx_buffer) {
 582                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 583                 if (!spidev->tx_buffer) {
 584                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 585                         status = -ENOMEM;
 586                         goto err_find_dev;
 587                 }
 588         }
 589
 590         if (!spidev->rx_buffer) {
 591                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 592                 if (!spidev->rx_buffer) {
 593                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 594                         status = -ENOMEM;
 595                         goto err_alloc_rx_buf;
 596                 }
 597         }
 598
 599         spidev->users++;
 600         filp->private_data = spidev;
 601         stream_open(inode, filp);
 602
 603         mutex_unlock(&device_list_lock);
 604         return 0;
 605
 606 err_alloc_rx_buf:
 607         kfree(spidev->tx_buffer);
 608         spidev->tx_buffer = NULL;
 609 err_find_dev:
 610         mutex_unlock(&device_list_lock);
 611         return status;
 612 }
 613
 614 static int spidev_release(struct inode *inode, struct file *filp)
 615 {
 616         struct spidev_data      *spidev;
 617         int                     dofree;
 618
 619         mutex_lock(&device_list_lock);
 620         spidev = filp->private_data;
 621         filp->private_data = NULL;
 622
 623         spin_lock_irq(&spidev->spi_lock);
 624         /* ... after we unbound from the underlying device? */
 625         dofree = (spidev->spi == NULL);
 626         spin_unlock_irq(&spidev->spi_lock);
 627
 628         /* last close? */
 629         spidev->users--;
 630         if (!spidev->users) {
 631
 632                 kfree(spidev->tx_buffer);
 633                 spidev->tx_buffer = NULL;
 634
 635                 kfree(spidev->rx_buffer);
 636                 spidev->rx_buffer = NULL;
 637
 638                 if (dofree)
 639                         kfree(spidev);
 640                 else
 641                         spidev->speed_hz = spidev->spi->max_speed_hz;
 642         }
 643 #ifdef CONFIG_SPI_SLAVE
 644         if (!dofree)
 645                 spi_slave_abort(spidev->spi);
 646 #endif
 647         mutex_unlock(&device_list_lock);
 648
 649         return 0;
 650 }
 651
 652 static const struct file_operations spidev_fops = {
 653         .owner =        THIS_MODULE,
 654         /* REVISIT switch to aio primitives, so that userspace
 655          * gets more complete API coverage.  It'll simplify things
 656          * too, except for the locking.
 657          */
 658         .write =        spidev_write,
 659         .read =         spidev_read,
 660         .unlocked_ioctl = spidev_ioctl,
 661         .compat_ioctl = spidev_compat_ioctl,
 662         .open =         spidev_open,
 663         .release =      spidev_release,
 664         .llseek =       no_llseek,
 665 };
 666
 667 /*-------------------------------------------------------------------------*/
 668
 669 /* The main reason to have this class is to make mdev/udev create the
 670  * /dev/spidevB.C character device nodes exposing our userspace API.
 671  * It also simplifies memory management.
 672  */
 673
 674 static struct class *spidev_class;
 675
 676 #ifdef CONFIG_OF
 677 static const struct of_device_id spidev_dt_ids[] = {
 678         { .compatible = "rohm,dh2228fv" },
 679         { .compatible = "lineartechnology,ltc2488" },
 680         { .compatible = "semtech,sx1301" },
 681         { .compatible = "lwn,bk4" },
 682         { .compatible = "dh,dhcom-board" },
 683         { .compatible = "menlo,m53cpld" },
 684         { .compatible = "cisco,spi-petra" },
 685         { .compatible = "micron,spi-authenta" },
 686         {},
 687 };
 688 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 689 #endif
 690
 691 #ifdef CONFIG_ACPI
 692
 693 /* Dummy SPI devices not to be used in production systems */
 694 #define SPIDEV_ACPI_DUMMY       1
 695
 696 static const struct acpi_device_id spidev_acpi_ids[] = {
 697         /*
 698          * The ACPI SPT000* devices are only meant for development and
 699          * testing. Systems used in production should have a proper ACPI
 700          * description of the connected peripheral and they should also use
 701          * a proper driver instead of poking directly to the SPI bus.
 702          */
 703         { "SPT0001", SPIDEV_ACPI_DUMMY },
 704         { "SPT0002", SPIDEV_ACPI_DUMMY },
 705         { "SPT0003", SPIDEV_ACPI_DUMMY },
 706         {},
 707 };
 708 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 709
 710 static void spidev_probe_acpi(struct spi_device *spi)
 711 {
 712         const struct acpi_device_id *id;
 713
 714         if (!has_acpi_companion(&spi->dev))
 715                 return;
 716
 717         id = acpi_match_device(spidev_acpi_ids, &spi->dev);
 718         if (WARN_ON(!id))
 719                 return;
 720
 721         if (id->driver_data == SPIDEV_ACPI_DUMMY)
 722                 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
 723 }
 724 #else
 725 static inline void spidev_probe_acpi(struct spi_device *spi) {}
 726 #endif
 727
 728 /*-------------------------------------------------------------------------*/
 729
 730 static int spidev_probe(struct spi_device *spi)
 731 {
 732         struct spidev_data      *spidev;
 733         int                     status;
 734         unsigned long           minor;
 735
 736         /*
 737          * spidev should never be referenced in DT without a specific
 738          * compatible string, it is a Linux implementation thing
 739          * rather than a description of the hardware.
 740          */
 741         WARN(spi->dev.of_node &&
 742              of_device_is_compatible(spi->dev.of_node, "spidev"),
 743              "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
 744
 745         spidev_probe_acpi(spi);
 746
 747         /* Allocate driver data */
 748         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 749         if (!spidev)
 750                 return -ENOMEM;
 751
 752         /* Initialize the driver data */
 753         spidev->spi = spi;
 754         spin_lock_init(&spidev->spi_lock);
 755         mutex_init(&spidev->buf_lock);
 756
 757         INIT_LIST_HEAD(&spidev->device_entry);
 758
 759         /* If we can allocate a minor number, hook up this device.
 760          * Reusing minors is fine so long as udev or mdev is working.
 761          */
 762         mutex_lock(&device_list_lock);
 763         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 764         if (minor < N_SPI_MINORS) {
 765                 struct device *dev;
 766
 767                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 768                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 769                                     spidev, "spidev%d.%d",
 770                                     spi->master->bus_num, spi->chip_select);
 771                 status = PTR_ERR_OR_ZERO(dev);
 772         } else {
 773                 dev_dbg(&spi->dev, "no minor number available!\n");
 774                 status = -ENODEV;
 775         }
 776         if (status == 0) {
 777                 set_bit(minor, minors);
 778                 list_add(&spidev->device_entry, &device_list);
 779         }
 780         mutex_unlock(&device_list_lock);
 781
 782         spidev->speed_hz = spi->max_speed_hz;
 783
 784         if (status == 0)
 785                 spi_set_drvdata(spi, spidev);
 786         else
 787                 kfree(spidev);
 788
 789         return status;
 790 }
 791
 792 static int spidev_remove(struct spi_device *spi)
 793 {
 794         struct spidev_data      *spidev = spi_get_drvdata(spi);
 795
 796         /* prevent new opens */
 797         mutex_lock(&device_list_lock);
 798         /* make sure ops on existing fds can abort cleanly */
 799         spin_lock_irq(&spidev->spi_lock);
 800         spidev->spi = NULL;
 801         spin_unlock_irq(&spidev->spi_lock);
 802
 803         list_del(&spidev->device_entry);
 804         device_destroy(spidev_class, spidev->devt);
 805         clear_bit(MINOR(spidev->devt), minors);
 806         if (spidev->users == 0)
 807                 kfree(spidev);
 808         mutex_unlock(&device_list_lock);
 809
 810         return 0;
 811 }
 812
 813 static struct spi_driver spidev_spi_driver = {
 814         .driver = {
 815                 .name =         "spidev",
 816                 .of_match_table = of_match_ptr(spidev_dt_ids),
 817                 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
 818         },
 819         .probe =        spidev_probe,
 820         .remove =       spidev_remove,
 821
 822         /* NOTE:  suspend/resume methods are not necessary here.
 823          * We don't do anything except pass the requests to/from
 824          * the underlying controller.  The refrigerator handles
 825          * most issues; the controller driver handles the rest.
 826          */
 827 };
 828
 829 /*-------------------------------------------------------------------------*/
 830
 831 static int __init spidev_init(void)
 832 {
 833         int status;
 834
 835         /* Claim our 256 reserved device numbers.  Then register a class
 836          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 837          * the driver which manages those device numbers.
 838          */
 839         BUILD_BUG_ON(N_SPI_MINORS > 256);
 840         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 841         if (status < 0)
 842                 return status;
 843
 844         spidev_class = class_create(THIS_MODULE, "spidev");
 845         if (IS_ERR(spidev_class)) {
 846                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 847                 return PTR_ERR(spidev_class);
 848         }
 849
 850         status = spi_register_driver(&spidev_spi_driver);
 851         if (status < 0) {
 852                 class_destroy(spidev_class);
 853                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 854         }
 855         return status;
 856 }
 857 module_init(spidev_init);
 858
 859 static void __exit spidev_exit(void)
 860 {
 861         spi_unregister_driver(&spidev_spi_driver);
 862         class_destroy(spidev_class);
 863         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 864 }
 865 module_exit(spidev_exit);
 866
 867 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 868 MODULE_DESCRIPTION("User mode SPI device interface");
 869 MODULE_LICENSE("GPL");
 870 MODULE_ALIAS("spi:spidev");