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/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.value = u_tmp->delay_usecs;
 269                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 270                 k_tmp->speed_hz = u_tmp->speed_hz;
 271                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 272                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 273                 if (!k_tmp->speed_hz)
 274                         k_tmp->speed_hz = spidev->speed_hz;
 275 #ifdef VERBOSE
 276                 dev_dbg(&spidev->spi->dev,
 277                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 278                         k_tmp->len,
 279                         k_tmp->rx_buf ? "rx " : "",
 280                         k_tmp->tx_buf ? "tx " : "",
 281                         k_tmp->cs_change ? "cs " : "",
 282                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 283                         k_tmp->delay.value,
 284                         k_tmp->word_delay.value,
 285                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 286 #endif
 287                 spi_message_add_tail(k_tmp, &msg);
 288         }
 289
 290         status = spidev_sync(spidev, &msg);
 291         if (status < 0)
 292                 goto done;
 293
 294         /* copy any rx data out of bounce buffer */
 295         rx_buf = spidev->rx_buffer;
 296         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 297                 if (u_tmp->rx_buf) {
 298                         if (copy_to_user((u8 __user *)
 299                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
 300                                         u_tmp->len)) {
 301                                 status = -EFAULT;
 302                                 goto done;
 303                         }
 304                         rx_buf += u_tmp->len;
 305                 }
 306         }
 307         status = total;
 308
 309 done:
 310         kfree(k_xfers);
 311         return status;
 312 }
 313
 314 static struct spi_ioc_transfer *
 315 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 316                 unsigned *n_ioc)
 317 {
 318         u32     tmp;
 319
 320         /* Check type, command number and direction */
 321         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 322                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 323                         || _IOC_DIR(cmd) != _IOC_WRITE)
 324                 return ERR_PTR(-ENOTTY);
 325
 326         tmp = _IOC_SIZE(cmd);
 327         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 328                 return ERR_PTR(-EINVAL);
 329         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 330         if (*n_ioc == 0)
 331                 return NULL;
 332
 333         /* copy into scratch area */
 334         return memdup_user(u_ioc, tmp);
 335 }
 336
 337 static long
 338 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 339 {
 340         int                     retval = 0;
 341         struct spidev_data      *spidev;
 342         struct spi_device       *spi;
 343         u32                     tmp;
 344         unsigned                n_ioc;
 345         struct spi_ioc_transfer *ioc;
 346
 347         /* Check type and command number */
 348         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 349                 return -ENOTTY;
 350
 351         /* guard against device removal before, or while,
 352          * we issue this ioctl.
 353          */
 354         spidev = filp->private_data;
 355         spin_lock_irq(&spidev->spi_lock);
 356         spi = spi_dev_get(spidev->spi);
 357         spin_unlock_irq(&spidev->spi_lock);
 358
 359         if (spi == NULL)
 360                 return -ESHUTDOWN;
 361
 362         /* use the buffer lock here for triple duty:
 363          *  - prevent I/O (from us) so calling spi_setup() is safe;
 364          *  - prevent concurrent SPI_IOC_WR_* from morphing
 365          *    data fields while SPI_IOC_RD_* reads them;
 366          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 367          */
 368         mutex_lock(&spidev->buf_lock);
 369
 370         switch (cmd) {
 371         /* read requests */
 372         case SPI_IOC_RD_MODE:
 373                 retval = put_user(spi->mode & SPI_MODE_MASK,
 374                                         (__u8 __user *)arg);
 375                 break;
 376         case SPI_IOC_RD_MODE32:
 377                 retval = put_user(spi->mode & SPI_MODE_MASK,
 378                                         (__u32 __user *)arg);
 379                 break;
 380         case SPI_IOC_RD_LSB_FIRST:
 381                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 382                                         (__u8 __user *)arg);
 383                 break;
 384         case SPI_IOC_RD_BITS_PER_WORD:
 385                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 386                 break;
 387         case SPI_IOC_RD_MAX_SPEED_HZ:
 388                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 389                 break;
 390
 391         /* write requests */
 392         case SPI_IOC_WR_MODE:
 393         case SPI_IOC_WR_MODE32:
 394                 if (cmd == SPI_IOC_WR_MODE)
 395                         retval = get_user(tmp, (u8 __user *)arg);
 396                 else
 397                         retval = get_user(tmp, (u32 __user *)arg);
 398                 if (retval == 0) {
 399                         struct spi_controller *ctlr = spi->controller;
 400                         u32     save = spi->mode;
 401
 402                         if (tmp & ~SPI_MODE_MASK) {
 403                                 retval = -EINVAL;
 404                                 break;
 405                         }
 406
 407                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 408                             ctlr->cs_gpiods[spi->chip_select])
 409                                 tmp |= SPI_CS_HIGH;
 410
 411                         tmp |= spi->mode & ~SPI_MODE_MASK;
 412                         spi->mode = (u16)tmp;
 413                         retval = spi_setup(spi);
 414                         if (retval < 0)
 415                                 spi->mode = save;
 416                         else
 417                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 418                 }
 419                 break;
 420         case SPI_IOC_WR_LSB_FIRST:
 421                 retval = get_user(tmp, (__u8 __user *)arg);
 422                 if (retval == 0) {
 423                         u32     save = spi->mode;
 424
 425                         if (tmp)
 426                                 spi->mode |= SPI_LSB_FIRST;
 427                         else
 428                                 spi->mode &= ~SPI_LSB_FIRST;
 429                         retval = spi_setup(spi);
 430                         if (retval < 0)
 431                                 spi->mode = save;
 432                         else
 433                                 dev_dbg(&spi->dev, "%csb first\n",
 434                                                 tmp ? 'l' : 'm');
 435                 }
 436                 break;
 437         case SPI_IOC_WR_BITS_PER_WORD:
 438                 retval = get_user(tmp, (__u8 __user *)arg);
 439                 if (retval == 0) {
 440                         u8      save = spi->bits_per_word;
 441
 442                         spi->bits_per_word = tmp;
 443                         retval = spi_setup(spi);
 444                         if (retval < 0)
 445                                 spi->bits_per_word = save;
 446                         else
 447                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 448                 }
 449                 break;
 450         case SPI_IOC_WR_MAX_SPEED_HZ:
 451                 retval = get_user(tmp, (__u32 __user *)arg);
 452                 if (retval == 0) {
 453                         u32     save = spi->max_speed_hz;
 454
 455                         spi->max_speed_hz = tmp;
 456                         retval = spi_setup(spi);
 457                         if (retval == 0) {
 458                                 spidev->speed_hz = tmp;
 459                                 dev_dbg(&spi->dev, "%d Hz (max)\n",
 460                                         spidev->speed_hz);
 461                         }
 462                         spi->max_speed_hz = save;
 463                 }
 464                 break;
 465
 466         default:
 467                 /* segmented and/or full-duplex I/O request */
 468                 /* Check message and copy into scratch area */
 469                 ioc = spidev_get_ioc_message(cmd,
 470                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 471                 if (IS_ERR(ioc)) {
 472                         retval = PTR_ERR(ioc);
 473                         break;
 474                 }
 475                 if (!ioc)
 476                         break;  /* n_ioc is also 0 */
 477
 478                 /* translate to spi_message, execute */
 479                 retval = spidev_message(spidev, ioc, n_ioc);
 480                 kfree(ioc);
 481                 break;
 482         }
 483
 484         mutex_unlock(&spidev->buf_lock);
 485         spi_dev_put(spi);
 486         return retval;
 487 }
 488
 489 #ifdef CONFIG_COMPAT
 490 static long
 491 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 492                 unsigned long arg)
 493 {
 494         struct spi_ioc_transfer __user  *u_ioc;
 495         int                             retval = 0;
 496         struct spidev_data              *spidev;
 497         struct spi_device               *spi;
 498         unsigned                        n_ioc, n;
 499         struct spi_ioc_transfer         *ioc;
 500
 501         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 502
 503         /* guard against device removal before, or while,
 504          * we issue this ioctl.
 505          */
 506         spidev = filp->private_data;
 507         spin_lock_irq(&spidev->spi_lock);
 508         spi = spi_dev_get(spidev->spi);
 509         spin_unlock_irq(&spidev->spi_lock);
 510
 511         if (spi == NULL)
 512                 return -ESHUTDOWN;
 513
 514         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 515         mutex_lock(&spidev->buf_lock);
 516
 517         /* Check message and copy into scratch area */
 518         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 519         if (IS_ERR(ioc)) {
 520                 retval = PTR_ERR(ioc);
 521                 goto done;
 522         }
 523         if (!ioc)
 524                 goto done;      /* n_ioc is also 0 */
 525
 526         /* Convert buffer pointers */
 527         for (n = 0; n < n_ioc; n++) {
 528                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 529                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 530         }
 531
 532         /* translate to spi_message, execute */
 533         retval = spidev_message(spidev, ioc, n_ioc);
 534         kfree(ioc);
 535
 536 done:
 537         mutex_unlock(&spidev->buf_lock);
 538         spi_dev_put(spi);
 539         return retval;
 540 }
 541
 542 static long
 543 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 544 {
 545         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 546                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 547                         && _IOC_DIR(cmd) == _IOC_WRITE)
 548                 return spidev_compat_ioc_message(filp, cmd, arg);
 549
 550         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 551 }
 552 #else
 553 #define spidev_compat_ioctl NULL
 554 #endif /* CONFIG_COMPAT */
 555
 556 static int spidev_open(struct inode *inode, struct file *filp)
 557 {
 558         struct spidev_data      *spidev;
 559         int                     status = -ENXIO;
 560
 561         mutex_lock(&device_list_lock);
 562
 563         list_for_each_entry(spidev, &device_list, device_entry) {
 564                 if (spidev->devt == inode->i_rdev) {
 565                         status = 0;
 566                         break;
 567                 }
 568         }
 569
 570         if (status) {
 571                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 572                 goto err_find_dev;
 573         }
 574
 575         if (!spidev->tx_buffer) {
 576                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 577                 if (!spidev->tx_buffer) {
 578                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 579                         status = -ENOMEM;
 580                         goto err_find_dev;
 581                 }
 582         }
 583
 584         if (!spidev->rx_buffer) {
 585                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 586                 if (!spidev->rx_buffer) {
 587                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 588                         status = -ENOMEM;
 589                         goto err_alloc_rx_buf;
 590                 }
 591         }
 592
 593         spidev->users++;
 594         filp->private_data = spidev;
 595         stream_open(inode, filp);
 596
 597         mutex_unlock(&device_list_lock);
 598         return 0;
 599
 600 err_alloc_rx_buf:
 601         kfree(spidev->tx_buffer);
 602         spidev->tx_buffer = NULL;
 603 err_find_dev:
 604         mutex_unlock(&device_list_lock);
 605         return status;
 606 }
 607
 608 static int spidev_release(struct inode *inode, struct file *filp)
 609 {
 610         struct spidev_data      *spidev;
 611
 612         mutex_lock(&device_list_lock);
 613         spidev = filp->private_data;
 614         filp->private_data = NULL;
 615
 616         /* last close? */
 617         spidev->users--;
 618         if (!spidev->users) {
 619                 int             dofree;
 620
 621                 kfree(spidev->tx_buffer);
 622                 spidev->tx_buffer = NULL;
 623
 624                 kfree(spidev->rx_buffer);
 625                 spidev->rx_buffer = NULL;
 626
 627                 spin_lock_irq(&spidev->spi_lock);
 628                 if (spidev->spi)
 629                         spidev->speed_hz = spidev->spi->max_speed_hz;
 630
 631                 /* ... after we unbound from the underlying device? */
 632                 dofree = (spidev->spi == NULL);
 633                 spin_unlock_irq(&spidev->spi_lock);
 634
 635                 if (dofree)
 636                         kfree(spidev);
 637         }
 638 #ifdef CONFIG_SPI_SLAVE
 639         spi_slave_abort(spidev->spi);
 640 #endif
 641         mutex_unlock(&device_list_lock);
 642
 643         return 0;
 644 }
 645
 646 static const struct file_operations spidev_fops = {
 647         .owner =        THIS_MODULE,
 648         /* REVISIT switch to aio primitives, so that userspace
 649          * gets more complete API coverage.  It'll simplify things
 650          * too, except for the locking.
 651          */
 652         .write =        spidev_write,
 653         .read =         spidev_read,
 654         .unlocked_ioctl = spidev_ioctl,
 655         .compat_ioctl = spidev_compat_ioctl,
 656         .open =         spidev_open,
 657         .release =      spidev_release,
 658         .llseek =       no_llseek,
 659 };
 660
 661 /*-------------------------------------------------------------------------*/
 662
 663 /* The main reason to have this class is to make mdev/udev create the
 664  * /dev/spidevB.C character device nodes exposing our userspace API.
 665  * It also simplifies memory management.
 666  */
 667
 668 static struct class *spidev_class;
 669
 670 #ifdef CONFIG_OF
 671 static const struct of_device_id spidev_dt_ids[] = {
 672         { .compatible = "rohm,dh2228fv" },
 673         { .compatible = "lineartechnology,ltc2488" },
 674         { .compatible = "ge,achc" },
 675         { .compatible = "semtech,sx1301" },
 676         { .compatible = "lwn,bk4" },
 677         { .compatible = "dh,dhcom-board" },
 678         { .compatible = "menlo,m53cpld" },
 679         {},
 680 };
 681 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 682 #endif
 683
 684 #ifdef CONFIG_ACPI
 685
 686 /* Dummy SPI devices not to be used in production systems */
 687 #define SPIDEV_ACPI_DUMMY       1
 688
 689 static const struct acpi_device_id spidev_acpi_ids[] = {
 690         /*
 691          * The ACPI SPT000* devices are only meant for development and
 692          * testing. Systems used in production should have a proper ACPI
 693          * description of the connected peripheral and they should also use
 694          * a proper driver instead of poking directly to the SPI bus.
 695          */
 696         { "SPT0001", SPIDEV_ACPI_DUMMY },
 697         { "SPT0002", SPIDEV_ACPI_DUMMY },
 698         { "SPT0003", SPIDEV_ACPI_DUMMY },
 699         {},
 700 };
 701 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 702
 703 static void spidev_probe_acpi(struct spi_device *spi)
 704 {
 705         const struct acpi_device_id *id;
 706
 707         if (!has_acpi_companion(&spi->dev))
 708                 return;
 709
 710         id = acpi_match_device(spidev_acpi_ids, &spi->dev);
 711         if (WARN_ON(!id))
 712                 return;
 713
 714         if (id->driver_data == SPIDEV_ACPI_DUMMY)
 715                 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
 716 }
 717 #else
 718 static inline void spidev_probe_acpi(struct spi_device *spi) {}
 719 #endif
 720
 721 /*-------------------------------------------------------------------------*/
 722
 723 static int spidev_probe(struct spi_device *spi)
 724 {
 725         struct spidev_data      *spidev;
 726         int                     status;
 727         unsigned long           minor;
 728
 729         /*
 730          * spidev should never be referenced in DT without a specific
 731          * compatible string, it is a Linux implementation thing
 732          * rather than a description of the hardware.
 733          */
 734         WARN(spi->dev.of_node &&
 735              of_device_is_compatible(spi->dev.of_node, "spidev"),
 736              "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
 737
 738         spidev_probe_acpi(spi);
 739
 740         /* Allocate driver data */
 741         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 742         if (!spidev)
 743                 return -ENOMEM;
 744
 745         /* Initialize the driver data */
 746         spidev->spi = spi;
 747         spin_lock_init(&spidev->spi_lock);
 748         mutex_init(&spidev->buf_lock);
 749
 750         INIT_LIST_HEAD(&spidev->device_entry);
 751
 752         /* If we can allocate a minor number, hook up this device.
 753          * Reusing minors is fine so long as udev or mdev is working.
 754          */
 755         mutex_lock(&device_list_lock);
 756         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 757         if (minor < N_SPI_MINORS) {
 758                 struct device *dev;
 759
 760                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 761                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 762                                     spidev, "spidev%d.%d",
 763                                     spi->master->bus_num, spi->chip_select);
 764                 status = PTR_ERR_OR_ZERO(dev);
 765         } else {
 766                 dev_dbg(&spi->dev, "no minor number available!\n");
 767                 status = -ENODEV;
 768         }
 769         if (status == 0) {
 770                 set_bit(minor, minors);
 771                 list_add(&spidev->device_entry, &device_list);
 772         }
 773         mutex_unlock(&device_list_lock);
 774
 775         spidev->speed_hz = spi->max_speed_hz;
 776
 777         if (status == 0)
 778                 spi_set_drvdata(spi, spidev);
 779         else
 780                 kfree(spidev);
 781
 782         return status;
 783 }
 784
 785 static int spidev_remove(struct spi_device *spi)
 786 {
 787         struct spidev_data      *spidev = spi_get_drvdata(spi);
 788
 789         /* make sure ops on existing fds can abort cleanly */
 790         spin_lock_irq(&spidev->spi_lock);
 791         spidev->spi = NULL;
 792         spin_unlock_irq(&spidev->spi_lock);
 793
 794         /* prevent new opens */
 795         mutex_lock(&device_list_lock);
 796         list_del(&spidev->device_entry);
 797         device_destroy(spidev_class, spidev->devt);
 798         clear_bit(MINOR(spidev->devt), minors);
 799         if (spidev->users == 0)
 800                 kfree(spidev);
 801         mutex_unlock(&device_list_lock);
 802
 803         return 0;
 804 }
 805
 806 static struct spi_driver spidev_spi_driver = {
 807         .driver = {
 808                 .name =         "spidev",
 809                 .of_match_table = of_match_ptr(spidev_dt_ids),
 810                 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
 811         },
 812         .probe =        spidev_probe,
 813         .remove =       spidev_remove,
 814
 815         /* NOTE:  suspend/resume methods are not necessary here.
 816          * We don't do anything except pass the requests to/from
 817          * the underlying controller.  The refrigerator handles
 818          * most issues; the controller driver handles the rest.
 819          */
 820 };
 821
 822 /*-------------------------------------------------------------------------*/
 823
 824 static int __init spidev_init(void)
 825 {
 826         int status;
 827
 828         /* Claim our 256 reserved device numbers.  Then register a class
 829          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 830          * the driver which manages those device numbers.
 831          */
 832         BUILD_BUG_ON(N_SPI_MINORS > 256);
 833         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 834         if (status < 0)
 835                 return status;
 836
 837         spidev_class = class_create(THIS_MODULE, "spidev");
 838         if (IS_ERR(spidev_class)) {
 839                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 840                 return PTR_ERR(spidev_class);
 841         }
 842
 843         status = spi_register_driver(&spidev_spi_driver);
 844         if (status < 0) {
 845                 class_destroy(spidev_class);
 846                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 847         }
 848         return status;
 849 }
 850 module_init(spidev_init);
 851
 852 static void __exit spidev_exit(void)
 853 {
 854         spi_unregister_driver(&spidev_spi_driver);
 855         class_destroy(spidev_class);
 856         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 857 }
 858 module_exit(spidev_exit);
 859
 860 MODULE_AUTHOR("Andrea Paterniani, <[email protected]>");
 861 MODULE_DESCRIPTION("User mode SPI device interface");
 862 MODULE_LICENSE("GPL");
 863 MODULE_ALIAS("spi:spidev");