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_CPHA | SPI_CPOL | 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_RX_DUAL | SPI_RX_QUAD)
  66
  67 struct spidev_data {
  68         dev_t                   devt;
  69         spinlock_t              spi_lock;
  70         struct spi_device       *spi;
  71         struct list_head        device_entry;
  72
  73         /* TX/RX buffers are NULL unless this device is open (users > 0) */
  74         struct mutex            buf_lock;
  75         unsigned                users;
  76         u8                      *tx_buffer;
  77         u8                      *rx_buffer;
  78         u32                     speed_hz;
  79 };
  80
  81 static LIST_HEAD(device_list);
  82 static DEFINE_MUTEX(device_list_lock);
  83
  84 static unsigned bufsiz = 4096;
  85 module_param(bufsiz, uint, S_IRUGO);
  86 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  87
  88 /*-------------------------------------------------------------------------*/
  89
  90 static ssize_t
  91 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
  92 {
  93         int status;
  94         struct spi_device *spi;
  95
  96         spin_lock_irq(&spidev->spi_lock);
  97         spi = spidev->spi;
  98         spin_unlock_irq(&spidev->spi_lock);
  99
 100         if (spi == NULL)
 101                 status = -ESHUTDOWN;
 102         else
 103                 status = spi_sync(spi, message);
 104
 105         if (status == 0)
 106                 status = message->actual_length;
 107
 108         return status;
 109 }
 110
 111 static inline ssize_t
 112 spidev_sync_write(struct spidev_data *spidev, size_t len)
 113 {
 114         struct spi_transfer     t = {
 115                         .tx_buf         = spidev->tx_buffer,
 116                         .len            = len,
 117                         .speed_hz       = spidev->speed_hz,
 118                 };
 119         struct spi_message      m;
 120
 121         spi_message_init(&m);
 122         spi_message_add_tail(&t, &m);
 123         return spidev_sync(spidev, &m);
 124 }
 125
 126 static inline ssize_t
 127 spidev_sync_read(struct spidev_data *spidev, size_t len)
 128 {
 129         struct spi_transfer     t = {
 130                         .rx_buf         = spidev->rx_buffer,
 131                         .len            = len,
 132                         .speed_hz       = spidev->speed_hz,
 133                 };
 134         struct spi_message      m;
 135
 136         spi_message_init(&m);
 137         spi_message_add_tail(&t, &m);
 138         return spidev_sync(spidev, &m);
 139 }
 140
 141 /*-------------------------------------------------------------------------*/
 142
 143 /* Read-only message with current device setup */
 144 static ssize_t
 145 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 146 {
 147         struct spidev_data      *spidev;
 148         ssize_t                 status = 0;
 149
 150         /* chipselect only toggles at start or end of operation */
 151         if (count > bufsiz)
 152                 return -EMSGSIZE;
 153
 154         spidev = filp->private_data;
 155
 156         mutex_lock(&spidev->buf_lock);
 157         status = spidev_sync_read(spidev, count);
 158         if (status > 0) {
 159                 unsigned long   missing;
 160
 161                 missing = copy_to_user(buf, spidev->rx_buffer, status);
 162                 if (missing == status)
 163                         status = -EFAULT;
 164                 else
 165                         status = status - missing;
 166         }
 167         mutex_unlock(&spidev->buf_lock);
 168
 169         return status;
 170 }
 171
 172 /* Write-only message with current device setup */
 173 static ssize_t
 174 spidev_write(struct file *filp, const char __user *buf,
 175                 size_t count, loff_t *f_pos)
 176 {
 177         struct spidev_data      *spidev;
 178         ssize_t                 status = 0;
 179         unsigned long           missing;
 180
 181         /* chipselect only toggles at start or end of operation */
 182         if (count > bufsiz)
 183                 return -EMSGSIZE;
 184
 185         spidev = filp->private_data;
 186
 187         mutex_lock(&spidev->buf_lock);
 188         missing = copy_from_user(spidev->tx_buffer, buf, count);
 189         if (missing == 0)
 190                 status = spidev_sync_write(spidev, count);
 191         else
 192                 status = -EFAULT;
 193         mutex_unlock(&spidev->buf_lock);
 194
 195         return status;
 196 }
 197
 198 static int spidev_message(struct spidev_data *spidev,
 199                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 200 {
 201         struct spi_message      msg;
 202         struct spi_transfer     *k_xfers;
 203         struct spi_transfer     *k_tmp;
 204         struct spi_ioc_transfer *u_tmp;
 205         unsigned                n, total, tx_total, rx_total;
 206         u8                      *tx_buf, *rx_buf;
 207         int                     status = -EFAULT;
 208
 209         spi_message_init(&msg);
 210         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 211         if (k_xfers == NULL)
 212                 return -ENOMEM;
 213
 214         /* Construct spi_message, copying any tx data to bounce buffer.
 215          * We walk the array of user-provided transfers, using each one
 216          * to initialize a kernel version of the same transfer.
 217          */
 218         tx_buf = spidev->tx_buffer;
 219         rx_buf = spidev->rx_buffer;
 220         total = 0;
 221         tx_total = 0;
 222         rx_total = 0;
 223         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 224                         n;
 225                         n--, k_tmp++, u_tmp++) {
 226                 k_tmp->len = u_tmp->len;
 227
 228                 total += k_tmp->len;
 229                 /* Since the function returns the total length of transfers
 230                  * on success, restrict the total to positive int values to
 231                  * avoid the return value looking like an error.  Also check
 232                  * each transfer length to avoid arithmetic overflow.
 233                  */
 234                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 235                         status = -EMSGSIZE;
 236                         goto done;
 237                 }
 238
 239                 if (u_tmp->rx_buf) {
 240                         /* this transfer needs space in RX bounce buffer */
 241                         rx_total += k_tmp->len;
 242                         if (rx_total > bufsiz) {
 243                                 status = -EMSGSIZE;
 244                                 goto done;
 245                         }
 246                         k_tmp->rx_buf = rx_buf;
 247                         rx_buf += k_tmp->len;
 248                 }
 249                 if (u_tmp->tx_buf) {
 250                         /* this transfer needs space in TX bounce buffer */
 251                         tx_total += k_tmp->len;
 252                         if (tx_total > bufsiz) {
 253                                 status = -EMSGSIZE;
 254                                 goto done;
 255                         }
 256                         k_tmp->tx_buf = tx_buf;
 257                         if (copy_from_user(tx_buf, (const u8 __user *)
 258                                                 (uintptr_t) u_tmp->tx_buf,
 259                                         u_tmp->len))
 260                                 goto done;
 261                         tx_buf += k_tmp->len;
 262                 }
 263
 264                 k_tmp->cs_change = !!u_tmp->cs_change;
 265                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 266                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 267                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 268                 k_tmp->delay_usecs = u_tmp->delay_usecs;
 269                 k_tmp->speed_hz = u_tmp->speed_hz;
 270                 k_tmp->word_delay_usecs = u_tmp->word_delay_usecs;
 271                 if (!k_tmp->speed_hz)
 272                         k_tmp->speed_hz = spidev->speed_hz;
 273 #ifdef VERBOSE
 274                 dev_dbg(&spidev->spi->dev,
 275                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 276                         u_tmp->len,
 277                         u_tmp->rx_buf ? "rx " : "",
 278                         u_tmp->tx_buf ? "tx " : "",
 279                         u_tmp->cs_change ? "cs " : "",
 280                         u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 281                         u_tmp->delay_usecs,
 282                         u_tmp->word_delay_usecs,
 283                         u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 284 #endif
 285                 spi_message_add_tail(k_tmp, &msg);
 286         }
 287
 288         status = spidev_sync(spidev, &msg);
 289         if (status < 0)
 290                 goto done;
 291
 292         /* copy any rx data out of bounce buffer */
 293         rx_buf = spidev->rx_buffer;
 294         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 295                 if (u_tmp->rx_buf) {
 296                         if (copy_to_user((u8 __user *)
 297                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
 298                                         u_tmp->len)) {
 299                                 status = -EFAULT;
 300                                 goto done;
 301                         }
 302                         rx_buf += u_tmp->len;
 303                 }
 304         }
 305         status = total;
 306
 307 done:
 308         kfree(k_xfers);
 309         return status;
 310 }
 311
 312 static struct spi_ioc_transfer *
 313 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 314                 unsigned *n_ioc)
 315 {
 316         u32     tmp;
 317
 318         /* Check type, command number and direction */
 319         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 320                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 321                         || _IOC_DIR(cmd) != _IOC_WRITE)
 322                 return ERR_PTR(-ENOTTY);
 323
 324         tmp = _IOC_SIZE(cmd);
 325         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 326                 return ERR_PTR(-EINVAL);
 327         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 328         if (*n_ioc == 0)
 329                 return NULL;
 330
 331         /* copy into scratch area */
 332         return memdup_user(u_ioc, tmp);
 333 }
 334
 335 static long
 336 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 337 {
 338         int                     retval = 0;
 339         struct spidev_data      *spidev;
 340         struct spi_device       *spi;
 341         u32                     tmp;
 342         unsigned                n_ioc;
 343         struct spi_ioc_transfer *ioc;
 344
 345         /* Check type and command number */
 346         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 347                 return -ENOTTY;
 348
 349         /* guard against device removal before, or while,
 350          * we issue this ioctl.
 351          */
 352         spidev = filp->private_data;
 353         spin_lock_irq(&spidev->spi_lock);
 354         spi = spi_dev_get(spidev->spi);
 355         spin_unlock_irq(&spidev->spi_lock);
 356
 357         if (spi == NULL)
 358                 return -ESHUTDOWN;
 359
 360         /* use the buffer lock here for triple duty:
 361          *  - prevent I/O (from us) so calling spi_setup() is safe;
 362          *  - prevent concurrent SPI_IOC_WR_* from morphing
 363          *    data fields while SPI_IOC_RD_* reads them;
 364          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 365          */
 366         mutex_lock(&spidev->buf_lock);
 367
 368         switch (cmd) {
 369         /* read requests */
 370         case SPI_IOC_RD_MODE:
 371                 retval = put_user(spi->mode & SPI_MODE_MASK,
 372                                         (__u8 __user *)arg);
 373                 break;
 374         case SPI_IOC_RD_MODE32:
 375                 retval = put_user(spi->mode & SPI_MODE_MASK,
 376                                         (__u32 __user *)arg);
 377                 break;
 378         case SPI_IOC_RD_LSB_FIRST:
 379                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 380                                         (__u8 __user *)arg);
 381                 break;
 382         case SPI_IOC_RD_BITS_PER_WORD:
 383                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 384                 break;
 385         case SPI_IOC_RD_MAX_SPEED_HZ:
 386                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 387                 break;
 388
 389         /* write requests */
 390         case SPI_IOC_WR_MODE:
 391         case SPI_IOC_WR_MODE32:
 392                 if (cmd == SPI_IOC_WR_MODE)
 393                         retval = get_user(tmp, (u8 __user *)arg);
 394                 else
 395                         retval = get_user(tmp, (u32 __user *)arg);
 396                 if (retval == 0) {
 397                         u32     save = spi->mode;
 398
 399                         if (tmp & ~SPI_MODE_MASK) {
 400                                 retval = -EINVAL;
 401                                 break;
 402                         }
 403
 404                         tmp |= spi->mode & ~SPI_MODE_MASK;
 405                         spi->mode = (u16)tmp;
 406                         retval = spi_setup(spi);
 407                         if (retval < 0)
 408                                 spi->mode = save;
 409                         else
 410                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 411                 }
 412                 break;
 413         case SPI_IOC_WR_LSB_FIRST:
 414                 retval = get_user(tmp, (__u8 __user *)arg);
 415                 if (retval == 0) {
 416                         u32     save = spi->mode;
 417
 418                         if (tmp)
 419                                 spi->mode |= SPI_LSB_FIRST;
 420                         else
 421                                 spi->mode &= ~SPI_LSB_FIRST;
 422                         retval = spi_setup(spi);
 423                         if (retval < 0)
 424                                 spi->mode = save;
 425                         else
 426                                 dev_dbg(&spi->dev, "%csb first\n",
 427                                                 tmp ? 'l' : 'm');
 428                 }
 429                 break;
 430         case SPI_IOC_WR_BITS_PER_WORD:
 431                 retval = get_user(tmp, (__u8 __user *)arg);
 432                 if (retval == 0) {
 433                         u8      save = spi->bits_per_word;
 434
 435                         spi->bits_per_word = tmp;
 436                         retval = spi_setup(spi);
 437                         if (retval < 0)
 438                                 spi->bits_per_word = save;
 439                         else
 440                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 441                 }
 442                 break;
 443         case SPI_IOC_WR_MAX_SPEED_HZ:
 444                 retval = get_user(tmp, (__u32 __user *)arg);
 445                 if (retval == 0) {
 446                         u32     save = spi->max_speed_hz;
 447
 448                         spi->max_speed_hz = tmp;
 449                         retval = spi_setup(spi);
 450                         if (retval >= 0)
 451                                 spidev->speed_hz = tmp;
 452                         else
 453                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 454                         spi->max_speed_hz = save;
 455                 }
 456                 break;
 457
 458         default:
 459                 /* segmented and/or full-duplex I/O request */
 460                 /* Check message and copy into scratch area */
 461                 ioc = spidev_get_ioc_message(cmd,
 462                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 463                 if (IS_ERR(ioc)) {
 464                         retval = PTR_ERR(ioc);
 465                         break;
 466                 }
 467                 if (!ioc)
 468                         break;  /* n_ioc is also 0 */
 469
 470                 /* translate to spi_message, execute */
 471                 retval = spidev_message(spidev, ioc, n_ioc);
 472                 kfree(ioc);
 473                 break;
 474         }
 475
 476         mutex_unlock(&spidev->buf_lock);
 477         spi_dev_put(spi);
 478         return retval;
 479 }
 480
 481 #ifdef CONFIG_COMPAT
 482 static long
 483 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 484                 unsigned long arg)
 485 {
 486         struct spi_ioc_transfer __user  *u_ioc;
 487         int                             retval = 0;
 488         struct spidev_data              *spidev;
 489         struct spi_device               *spi;
 490         unsigned                        n_ioc, n;
 491         struct spi_ioc_transfer         *ioc;
 492
 493         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 494
 495         /* guard against device removal before, or while,
 496          * we issue this ioctl.
 497          */
 498         spidev = filp->private_data;
 499         spin_lock_irq(&spidev->spi_lock);
 500         spi = spi_dev_get(spidev->spi);
 501         spin_unlock_irq(&spidev->spi_lock);
 502
 503         if (spi == NULL)
 504                 return -ESHUTDOWN;
 505
 506         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 507         mutex_lock(&spidev->buf_lock);
 508
 509         /* Check message and copy into scratch area */
 510         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 511         if (IS_ERR(ioc)) {
 512                 retval = PTR_ERR(ioc);
 513                 goto done;
 514         }
 515         if (!ioc)
 516                 goto done;      /* n_ioc is also 0 */
 517
 518         /* Convert buffer pointers */
 519         for (n = 0; n < n_ioc; n++) {
 520                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 521                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 522         }
 523
 524         /* translate to spi_message, execute */
 525         retval = spidev_message(spidev, ioc, n_ioc);
 526         kfree(ioc);
 527
 528 done:
 529         mutex_unlock(&spidev->buf_lock);
 530         spi_dev_put(spi);
 531         return retval;
 532 }
 533
 534 static long
 535 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 536 {
 537         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 538                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 539                         && _IOC_DIR(cmd) == _IOC_WRITE)
 540                 return spidev_compat_ioc_message(filp, cmd, arg);
 541
 542         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 543 }
 544 #else
 545 #define spidev_compat_ioctl NULL
 546 #endif /* CONFIG_COMPAT */
 547
 548 static int spidev_open(struct inode *inode, struct file *filp)
 549 {
 550         struct spidev_data      *spidev;
 551         int                     status = -ENXIO;
 552
 553         mutex_lock(&device_list_lock);
 554
 555         list_for_each_entry(spidev, &device_list, device_entry) {
 556                 if (spidev->devt == inode->i_rdev) {
 557                         status = 0;
 558                         break;
 559                 }
 560         }
 561
 562         if (status) {
 563                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 564                 goto err_find_dev;
 565         }
 566
 567         if (!spidev->tx_buffer) {
 568                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 569                 if (!spidev->tx_buffer) {
 570                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 571                         status = -ENOMEM;
 572                         goto err_find_dev;
 573                 }
 574         }
 575
 576         if (!spidev->rx_buffer) {
 577                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 578                 if (!spidev->rx_buffer) {
 579                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 580                         status = -ENOMEM;
 581                         goto err_alloc_rx_buf;
 582                 }
 583         }
 584
 585         spidev->users++;
 586         filp->private_data = spidev;
 587         stream_open(inode, filp);
 588
 589         mutex_unlock(&device_list_lock);
 590         return 0;
 591
 592 err_alloc_rx_buf:
 593         kfree(spidev->tx_buffer);
 594         spidev->tx_buffer = NULL;
 595 err_find_dev:
 596         mutex_unlock(&device_list_lock);
 597         return status;
 598 }
 599
 600 static int spidev_release(struct inode *inode, struct file *filp)
 601 {
 602         struct spidev_data      *spidev;
 603
 604         mutex_lock(&device_list_lock);
 605         spidev = filp->private_data;
 606         filp->private_data = NULL;
 607
 608         /* last close? */
 609         spidev->users--;
 610         if (!spidev->users) {
 611                 int             dofree;
 612
 613                 kfree(spidev->tx_buffer);
 614                 spidev->tx_buffer = NULL;
 615
 616                 kfree(spidev->rx_buffer);
 617                 spidev->rx_buffer = NULL;
 618
 619                 spin_lock_irq(&spidev->spi_lock);
 620                 if (spidev->spi)
 621                         spidev->speed_hz = spidev->spi->max_speed_hz;
 622
 623                 /* ... after we unbound from the underlying device? */
 624                 dofree = (spidev->spi == NULL);
 625                 spin_unlock_irq(&spidev->spi_lock);
 626
 627                 if (dofree)
 628                         kfree(spidev);
 629         }
 630         mutex_unlock(&device_list_lock);
 631
 632         return 0;
 633 }
 634
 635 static const struct file_operations spidev_fops = {
 636         .owner =        THIS_MODULE,
 637         /* REVISIT switch to aio primitives, so that userspace
 638          * gets more complete API coverage.  It'll simplify things
 639          * too, except for the locking.
 640          */
 641         .write =        spidev_write,
 642         .read =         spidev_read,
 643         .unlocked_ioctl = spidev_ioctl,
 644         .compat_ioctl = spidev_compat_ioctl,
 645         .open =         spidev_open,
 646         .release =      spidev_release,
 647         .llseek =       no_llseek,
 648 };
 649
 650 /*-------------------------------------------------------------------------*/
 651
 652 /* The main reason to have this class is to make mdev/udev create the
 653  * /dev/spidevB.C character device nodes exposing our userspace API.
 654  * It also simplifies memory management.
 655  */
 656
 657 static struct class *spidev_class;
 658
 659 #ifdef CONFIG_OF
 660 static const struct of_device_id spidev_dt_ids[] = {
 661         { .compatible = "rohm,dh2228fv" },
 662         { .compatible = "lineartechnology,ltc2488" },
 663         { .compatible = "ge,achc" },
 664         { .compatible = "semtech,sx1301" },
 665         { .compatible = "lwn,bk4" },
 666         { .compatible = "dh,dhcom-board" },
 667         { .compatible = "menlo,m53cpld" },
 668         {},
 669 };
 670 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 671 #endif
 672
 673 #ifdef CONFIG_ACPI
 674
 675 /* Dummy SPI devices not to be used in production systems */
 676 #define SPIDEV_ACPI_DUMMY       1
 677
 678 static const struct acpi_device_id spidev_acpi_ids[] = {
 679         /*
 680          * The ACPI SPT000* devices are only meant for development and
 681          * testing. Systems used in production should have a proper ACPI
 682          * description of the connected peripheral and they should also use
 683          * a proper driver instead of poking directly to the SPI bus.
 684          */
 685         { "SPT0001", SPIDEV_ACPI_DUMMY },
 686         { "SPT0002", SPIDEV_ACPI_DUMMY },
 687         { "SPT0003", SPIDEV_ACPI_DUMMY },
 688         {},
 689 };
 690 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 691
 692 static void spidev_probe_acpi(struct spi_device *spi)
 693 {
 694         const struct acpi_device_id *id;
 695
 696         if (!has_acpi_companion(&spi->dev))
 697                 return;
 698
 699         id = acpi_match_device(spidev_acpi_ids, &spi->dev);
 700         if (WARN_ON(!id))
 701                 return;
 702
 703         if (id->driver_data == SPIDEV_ACPI_DUMMY)
 704                 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
 705 }
 706 #else
 707 static inline void spidev_probe_acpi(struct spi_device *spi) {}
 708 #endif
 709
 710 /*-------------------------------------------------------------------------*/
 711
 712 static int spidev_probe(struct spi_device *spi)
 713 {
 714         struct spidev_data      *spidev;
 715         int                     status;
 716         unsigned long           minor;
 717
 718         /*
 719          * spidev should never be referenced in DT without a specific
 720          * compatible string, it is a Linux implementation thing
 721          * rather than a description of the hardware.
 722          */
 723         WARN(spi->dev.of_node &&
 724              of_device_is_compatible(spi->dev.of_node, "spidev"),
 725              "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
 726
 727         spidev_probe_acpi(spi);
 728
 729         /* Allocate driver data */
 730         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 731         if (!spidev)
 732                 return -ENOMEM;
 733
 734         /* Initialize the driver data */
 735         spidev->spi = spi;
 736         spin_lock_init(&spidev->spi_lock);
 737         mutex_init(&spidev->buf_lock);
 738
 739         INIT_LIST_HEAD(&spidev->device_entry);
 740
 741         /* If we can allocate a minor number, hook up this device.
 742          * Reusing minors is fine so long as udev or mdev is working.
 743          */
 744         mutex_lock(&device_list_lock);
 745         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 746         if (minor < N_SPI_MINORS) {
 747                 struct device *dev;
 748
 749                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 750                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 751                                     spidev, "spidev%d.%d",
 752                                     spi->master->bus_num, spi->chip_select);
 753                 status = PTR_ERR_OR_ZERO(dev);
 754         } else {
 755                 dev_dbg(&spi->dev, "no minor number available!\n");
 756                 status = -ENODEV;
 757         }
 758         if (status == 0) {
 759                 set_bit(minor, minors);
 760                 list_add(&spidev->device_entry, &device_list);
 761         }
 762         mutex_unlock(&device_list_lock);
 763
 764         spidev->speed_hz = spi->max_speed_hz;
 765
 766         if (status == 0)
 767                 spi_set_drvdata(spi, spidev);
 768         else
 769                 kfree(spidev);
 770
 771         return status;
 772 }
 773
 774 static int spidev_remove(struct spi_device *spi)
 775 {
 776         struct spidev_data      *spidev = spi_get_drvdata(spi);
 777
 778         /* make sure ops on existing fds can abort cleanly */
 779         spin_lock_irq(&spidev->spi_lock);
 780         spidev->spi = NULL;
 781         spin_unlock_irq(&spidev->spi_lock);
 782
 783         /* prevent new opens */
 784         mutex_lock(&device_list_lock);
 785         list_del(&spidev->device_entry);
 786         device_destroy(spidev_class, spidev->devt);
 787         clear_bit(MINOR(spidev->devt), minors);
 788         if (spidev->users == 0)
 789                 kfree(spidev);
 790         mutex_unlock(&device_list_lock);
 791
 792         return 0;
 793 }
 794
 795 static struct spi_driver spidev_spi_driver = {
 796         .driver = {
 797                 .name =         "spidev",
 798                 .of_match_table = of_match_ptr(spidev_dt_ids),
 799                 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
 800         },
 801         .probe =        spidev_probe,
 802         .remove =       spidev_remove,
 803
 804         /* NOTE:  suspend/resume methods are not necessary here.
 805          * We don't do anything except pass the requests to/from
 806          * the underlying controller.  The refrigerator handles
 807          * most issues; the controller driver handles the rest.
 808          */
 809 };
 810
 811 /*-------------------------------------------------------------------------*/
 812
 813 static int __init spidev_init(void)
 814 {
 815         int status;
 816
 817         /* Claim our 256 reserved device numbers.  Then register a class
 818          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 819          * the driver which manages those device numbers.
 820          */
 821         BUILD_BUG_ON(N_SPI_MINORS > 256);
 822         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 823         if (status < 0)
 824                 return status;
 825
 826         spidev_class = class_create(THIS_MODULE, "spidev");
 827         if (IS_ERR(spidev_class)) {
 828                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 829                 return PTR_ERR(spidev_class);
 830         }
 831
 832         status = spi_register_driver(&spidev_spi_driver);
 833         if (status < 0) {
 834                 class_destroy(spidev_class);
 835                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 836         }
 837         return status;
 838 }
 839 module_init(spidev_init);
 840
 841 static void __exit spidev_exit(void)
 842 {
 843         spi_unregister_driver(&spidev_spi_driver);
 844         class_destroy(spidev_class);
 845         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 846 }
 847 module_exit(spidev_exit);
 848
 849 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 850 MODULE_DESCRIPTION("User mode SPI device interface");
 851 MODULE_LICENSE("GPL");
 852 MODULE_ALIAS("spi:spidev");