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_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 = 0;
 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 = 0;
 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                 k_tmp->len = u_tmp->len;
 228
 229                 total += k_tmp->len;
 230                 /* Since the function returns the total length of transfers
 231                  * on success, restrict the total to positive int values to
 232                  * avoid the return value looking like an error.  Also check
 233                  * each transfer length to avoid arithmetic overflow.
 234                  */
 235                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 236                         status = -EMSGSIZE;
 237                         goto done;
 238                 }
 239
 240                 if (u_tmp->rx_buf) {
 241                         /* this transfer needs space in RX bounce buffer */
 242                         rx_total += k_tmp->len;
 243                         if (rx_total > bufsiz) {
 244                                 status = -EMSGSIZE;
 245                                 goto done;
 246                         }
 247                         k_tmp->rx_buf = rx_buf;
 248                         rx_buf += k_tmp->len;
 249                 }
 250                 if (u_tmp->tx_buf) {
 251                         /* this transfer needs space in TX bounce buffer */
 252                         tx_total += k_tmp->len;
 253                         if (tx_total > bufsiz) {
 254                                 status = -EMSGSIZE;
 255                                 goto done;
 256                         }
 257                         k_tmp->tx_buf = tx_buf;
 258                         if (copy_from_user(tx_buf, (const u8 __user *)
 259                                                 (uintptr_t) u_tmp->tx_buf,
 260                                         u_tmp->len))
 261                                 goto done;
 262                         tx_buf += k_tmp->len;
 263                 }
 264
 265                 k_tmp->cs_change = !!u_tmp->cs_change;
 266                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 267                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 268                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 269                 k_tmp->delay.value = u_tmp->delay_usecs;
 270                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 271                 k_tmp->speed_hz = u_tmp->speed_hz;
 272                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 273                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 274                 if (!k_tmp->speed_hz)
 275                         k_tmp->speed_hz = spidev->speed_hz;
 276 #ifdef VERBOSE
 277                 dev_dbg(&spidev->spi->dev,
 278                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 279                         k_tmp->len,
 280                         k_tmp->rx_buf ? "rx " : "",
 281                         k_tmp->tx_buf ? "tx " : "",
 282                         k_tmp->cs_change ? "cs " : "",
 283                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 284                         k_tmp->delay.value,
 285                         k_tmp->word_delay.value,
 286                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 287 #endif
 288                 spi_message_add_tail(k_tmp, &msg);
 289         }
 290
 291         status = spidev_sync(spidev, &msg);
 292         if (status < 0)
 293                 goto done;
 294
 295         /* copy any rx data out of bounce buffer */
 296         rx_buf = spidev->rx_buffer;
 297         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 298                 if (u_tmp->rx_buf) {
 299                         if (copy_to_user((u8 __user *)
 300                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
 301                                         u_tmp->len)) {
 302                                 status = -EFAULT;
 303                                 goto done;
 304                         }
 305                         rx_buf += u_tmp->len;
 306                 }
 307         }
 308         status = total;
 309
 310 done:
 311         kfree(k_xfers);
 312         return status;
 313 }
 314
 315 static struct spi_ioc_transfer *
 316 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 317                 unsigned *n_ioc)
 318 {
 319         u32     tmp;
 320
 321         /* Check type, command number and direction */
 322         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 323                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 324                         || _IOC_DIR(cmd) != _IOC_WRITE)
 325                 return ERR_PTR(-ENOTTY);
 326
 327         tmp = _IOC_SIZE(cmd);
 328         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 329                 return ERR_PTR(-EINVAL);
 330         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 331         if (*n_ioc == 0)
 332                 return NULL;
 333
 334         /* copy into scratch area */
 335         return memdup_user(u_ioc, tmp);
 336 }
 337
 338 static long
 339 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 340 {
 341         int                     retval = 0;
 342         struct spidev_data      *spidev;
 343         struct spi_device       *spi;
 344         u32                     tmp;
 345         unsigned                n_ioc;
 346         struct spi_ioc_transfer *ioc;
 347
 348         /* Check type and command number */
 349         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 350                 return -ENOTTY;
 351
 352         /* guard against device removal before, or while,
 353          * we issue this ioctl.
 354          */
 355         spidev = filp->private_data;
 356         spin_lock_irq(&spidev->spi_lock);
 357         spi = spi_dev_get(spidev->spi);
 358         spin_unlock_irq(&spidev->spi_lock);
 359
 360         if (spi == NULL)
 361                 return -ESHUTDOWN;
 362
 363         /* use the buffer lock here for triple duty:
 364          *  - prevent I/O (from us) so calling spi_setup() is safe;
 365          *  - prevent concurrent SPI_IOC_WR_* from morphing
 366          *    data fields while SPI_IOC_RD_* reads them;
 367          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 368          */
 369         mutex_lock(&spidev->buf_lock);
 370
 371         switch (cmd) {
 372         /* read requests */
 373         case SPI_IOC_RD_MODE:
 374                 retval = put_user(spi->mode & SPI_MODE_MASK,
 375                                         (__u8 __user *)arg);
 376                 break;
 377         case SPI_IOC_RD_MODE32:
 378                 retval = put_user(spi->mode & SPI_MODE_MASK,
 379                                         (__u32 __user *)arg);
 380                 break;
 381         case SPI_IOC_RD_LSB_FIRST:
 382                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 383                                         (__u8 __user *)arg);
 384                 break;
 385         case SPI_IOC_RD_BITS_PER_WORD:
 386                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 387                 break;
 388         case SPI_IOC_RD_MAX_SPEED_HZ:
 389                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 390                 break;
 391
 392         /* write requests */
 393         case SPI_IOC_WR_MODE:
 394         case SPI_IOC_WR_MODE32:
 395                 if (cmd == SPI_IOC_WR_MODE)
 396                         retval = get_user(tmp, (u8 __user *)arg);
 397                 else
 398                         retval = get_user(tmp, (u32 __user *)arg);
 399                 if (retval == 0) {
 400                         struct spi_controller *ctlr = spi->controller;
 401                         u32     save = spi->mode;
 402
 403                         if (tmp & ~SPI_MODE_MASK) {
 404                                 retval = -EINVAL;
 405                                 break;
 406                         }
 407
 408                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 409                             ctlr->cs_gpiods[spi->chip_select])
 410                                 tmp |= SPI_CS_HIGH;
 411
 412                         tmp |= spi->mode & ~SPI_MODE_MASK;
 413                         spi->mode = (u16)tmp;
 414                         retval = spi_setup(spi);
 415                         if (retval < 0)
 416                                 spi->mode = save;
 417                         else
 418                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 419                 }
 420                 break;
 421         case SPI_IOC_WR_LSB_FIRST:
 422                 retval = get_user(tmp, (__u8 __user *)arg);
 423                 if (retval == 0) {
 424                         u32     save = spi->mode;
 425
 426                         if (tmp)
 427                                 spi->mode |= SPI_LSB_FIRST;
 428                         else
 429                                 spi->mode &= ~SPI_LSB_FIRST;
 430                         retval = spi_setup(spi);
 431                         if (retval < 0)
 432                                 spi->mode = save;
 433                         else
 434                                 dev_dbg(&spi->dev, "%csb first\n",
 435                                                 tmp ? 'l' : 'm');
 436                 }
 437                 break;
 438         case SPI_IOC_WR_BITS_PER_WORD:
 439                 retval = get_user(tmp, (__u8 __user *)arg);
 440                 if (retval == 0) {
 441                         u8      save = spi->bits_per_word;
 442
 443                         spi->bits_per_word = tmp;
 444                         retval = spi_setup(spi);
 445                         if (retval < 0)
 446                                 spi->bits_per_word = save;
 447                         else
 448                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 449                 }
 450                 break;
 451         case SPI_IOC_WR_MAX_SPEED_HZ:
 452                 retval = get_user(tmp, (__u32 __user *)arg);
 453                 if (retval == 0) {
 454                         u32     save = spi->max_speed_hz;
 455
 456                         spi->max_speed_hz = tmp;
 457                         retval = spi_setup(spi);
 458                         if (retval == 0) {
 459                                 spidev->speed_hz = tmp;
 460                                 dev_dbg(&spi->dev, "%d Hz (max)\n",
 461                                         spidev->speed_hz);
 462                         }
 463                         spi->max_speed_hz = save;
 464                 }
 465                 break;
 466
 467         default:
 468                 /* segmented and/or full-duplex I/O request */
 469                 /* Check message and copy into scratch area */
 470                 ioc = spidev_get_ioc_message(cmd,
 471                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 472                 if (IS_ERR(ioc)) {
 473                         retval = PTR_ERR(ioc);
 474                         break;
 475                 }
 476                 if (!ioc)
 477                         break;  /* n_ioc is also 0 */
 478
 479                 /* translate to spi_message, execute */
 480                 retval = spidev_message(spidev, ioc, n_ioc);
 481                 kfree(ioc);
 482                 break;
 483         }
 484
 485         mutex_unlock(&spidev->buf_lock);
 486         spi_dev_put(spi);
 487         return retval;
 488 }
 489
 490 #ifdef CONFIG_COMPAT
 491 static long
 492 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 493                 unsigned long arg)
 494 {
 495         struct spi_ioc_transfer __user  *u_ioc;
 496         int                             retval = 0;
 497         struct spidev_data              *spidev;
 498         struct spi_device               *spi;
 499         unsigned                        n_ioc, n;
 500         struct spi_ioc_transfer         *ioc;
 501
 502         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 503
 504         /* guard against device removal before, or while,
 505          * we issue this ioctl.
 506          */
 507         spidev = filp->private_data;
 508         spin_lock_irq(&spidev->spi_lock);
 509         spi = spi_dev_get(spidev->spi);
 510         spin_unlock_irq(&spidev->spi_lock);
 511
 512         if (spi == NULL)
 513                 return -ESHUTDOWN;
 514
 515         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 516         mutex_lock(&spidev->buf_lock);
 517
 518         /* Check message and copy into scratch area */
 519         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 520         if (IS_ERR(ioc)) {
 521                 retval = PTR_ERR(ioc);
 522                 goto done;
 523         }
 524         if (!ioc)
 525                 goto done;      /* n_ioc is also 0 */
 526
 527         /* Convert buffer pointers */
 528         for (n = 0; n < n_ioc; n++) {
 529                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 530                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 531         }
 532
 533         /* translate to spi_message, execute */
 534         retval = spidev_message(spidev, ioc, n_ioc);
 535         kfree(ioc);
 536
 537 done:
 538         mutex_unlock(&spidev->buf_lock);
 539         spi_dev_put(spi);
 540         return retval;
 541 }
 542
 543 static long
 544 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 545 {
 546         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 547                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 548                         && _IOC_DIR(cmd) == _IOC_WRITE)
 549                 return spidev_compat_ioc_message(filp, cmd, arg);
 550
 551         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 552 }
 553 #else
 554 #define spidev_compat_ioctl NULL
 555 #endif /* CONFIG_COMPAT */
 556
 557 static int spidev_open(struct inode *inode, struct file *filp)
 558 {
 559         struct spidev_data      *spidev;
 560         int                     status = -ENXIO;
 561
 562         mutex_lock(&device_list_lock);
 563
 564         list_for_each_entry(spidev, &device_list, device_entry) {
 565                 if (spidev->devt == inode->i_rdev) {
 566                         status = 0;
 567                         break;
 568                 }
 569         }
 570
 571         if (status) {
 572                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 573                 goto err_find_dev;
 574         }
 575
 576         if (!spidev->tx_buffer) {
 577                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 578                 if (!spidev->tx_buffer) {
 579                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 580                         status = -ENOMEM;
 581                         goto err_find_dev;
 582                 }
 583         }
 584
 585         if (!spidev->rx_buffer) {
 586                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 587                 if (!spidev->rx_buffer) {
 588                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 589                         status = -ENOMEM;
 590                         goto err_alloc_rx_buf;
 591                 }
 592         }
 593
 594         spidev->users++;
 595         filp->private_data = spidev;
 596         stream_open(inode, filp);
 597
 598         mutex_unlock(&device_list_lock);
 599         return 0;
 600
 601 err_alloc_rx_buf:
 602         kfree(spidev->tx_buffer);
 603         spidev->tx_buffer = NULL;
 604 err_find_dev:
 605         mutex_unlock(&device_list_lock);
 606         return status;
 607 }
 608
 609 static int spidev_release(struct inode *inode, struct file *filp)
 610 {
 611         struct spidev_data      *spidev;
 612
 613         mutex_lock(&device_list_lock);
 614         spidev = filp->private_data;
 615         filp->private_data = NULL;
 616
 617         /* last close? */
 618         spidev->users--;
 619         if (!spidev->users) {
 620                 int             dofree;
 621
 622                 kfree(spidev->tx_buffer);
 623                 spidev->tx_buffer = NULL;
 624
 625                 kfree(spidev->rx_buffer);
 626                 spidev->rx_buffer = NULL;
 627
 628                 spin_lock_irq(&spidev->spi_lock);
 629                 if (spidev->spi)
 630                         spidev->speed_hz = spidev->spi->max_speed_hz;
 631
 632                 /* ... after we unbound from the underlying device? */
 633                 dofree = (spidev->spi == NULL);
 634                 spin_unlock_irq(&spidev->spi_lock);
 635
 636                 if (dofree)
 637                         kfree(spidev);
 638         }
 639 #ifdef CONFIG_SPI_SLAVE
 640         spi_slave_abort(spidev->spi);
 641 #endif
 642         mutex_unlock(&device_list_lock);
 643
 644         return 0;
 645 }
 646
 647 static const struct file_operations spidev_fops = {
 648         .owner =        THIS_MODULE,
 649         /* REVISIT switch to aio primitives, so that userspace
 650          * gets more complete API coverage.  It'll simplify things
 651          * too, except for the locking.
 652          */
 653         .write =        spidev_write,
 654         .read =         spidev_read,
 655         .unlocked_ioctl = spidev_ioctl,
 656         .compat_ioctl = spidev_compat_ioctl,
 657         .open =         spidev_open,
 658         .release =      spidev_release,
 659         .llseek =       no_llseek,
 660 };
 661
 662 /*-------------------------------------------------------------------------*/
 663
 664 /* The main reason to have this class is to make mdev/udev create the
 665  * /dev/spidevB.C character device nodes exposing our userspace API.
 666  * It also simplifies memory management.
 667  */
 668
 669 static struct class *spidev_class;
 670
 671 #ifdef CONFIG_OF
 672 static const struct of_device_id spidev_dt_ids[] = {
 673         { .compatible = "rohm,dh2228fv" },
 674         { .compatible = "lineartechnology,ltc2488" },
 675         { .compatible = "ge,achc" },
 676         { .compatible = "semtech,sx1301" },
 677         { .compatible = "lwn,bk4" },
 678         { .compatible = "dh,dhcom-board" },
 679         { .compatible = "menlo,m53cpld" },
 680         {},
 681 };
 682 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 683 #endif
 684
 685 #ifdef CONFIG_ACPI
 686
 687 /* Dummy SPI devices not to be used in production systems */
 688 #define SPIDEV_ACPI_DUMMY       1
 689
 690 static const struct acpi_device_id spidev_acpi_ids[] = {
 691         /*
 692          * The ACPI SPT000* devices are only meant for development and
 693          * testing. Systems used in production should have a proper ACPI
 694          * description of the connected peripheral and they should also use
 695          * a proper driver instead of poking directly to the SPI bus.
 696          */
 697         { "SPT0001", SPIDEV_ACPI_DUMMY },
 698         { "SPT0002", SPIDEV_ACPI_DUMMY },
 699         { "SPT0003", SPIDEV_ACPI_DUMMY },
 700         {},
 701 };
 702 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 703
 704 static void spidev_probe_acpi(struct spi_device *spi)
 705 {
 706         const struct acpi_device_id *id;
 707
 708         if (!has_acpi_companion(&spi->dev))
 709                 return;
 710
 711         id = acpi_match_device(spidev_acpi_ids, &spi->dev);
 712         if (WARN_ON(!id))
 713                 return;
 714
 715         if (id->driver_data == SPIDEV_ACPI_DUMMY)
 716                 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
 717 }
 718 #else
 719 static inline void spidev_probe_acpi(struct spi_device *spi) {}
 720 #endif
 721
 722 /*-------------------------------------------------------------------------*/
 723
 724 static int spidev_probe(struct spi_device *spi)
 725 {
 726         struct spidev_data      *spidev;
 727         int                     status;
 728         unsigned long           minor;
 729
 730         /*
 731          * spidev should never be referenced in DT without a specific
 732          * compatible string, it is a Linux implementation thing
 733          * rather than a description of the hardware.
 734          */
 735         WARN(spi->dev.of_node &&
 736              of_device_is_compatible(spi->dev.of_node, "spidev"),
 737              "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
 738
 739         spidev_probe_acpi(spi);
 740
 741         /* Allocate driver data */
 742         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 743         if (!spidev)
 744                 return -ENOMEM;
 745
 746         /* Initialize the driver data */
 747         spidev->spi = spi;
 748         spin_lock_init(&spidev->spi_lock);
 749         mutex_init(&spidev->buf_lock);
 750
 751         INIT_LIST_HEAD(&spidev->device_entry);
 752
 753         /* If we can allocate a minor number, hook up this device.
 754          * Reusing minors is fine so long as udev or mdev is working.
 755          */
 756         mutex_lock(&device_list_lock);
 757         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 758         if (minor < N_SPI_MINORS) {
 759                 struct device *dev;
 760
 761                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 762                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 763                                     spidev, "spidev%d.%d",
 764                                     spi->master->bus_num, spi->chip_select);
 765                 status = PTR_ERR_OR_ZERO(dev);
 766         } else {
 767                 dev_dbg(&spi->dev, "no minor number available!\n");
 768                 status = -ENODEV;
 769         }
 770         if (status == 0) {
 771                 set_bit(minor, minors);
 772                 list_add(&spidev->device_entry, &device_list);
 773         }
 774         mutex_unlock(&device_list_lock);
 775
 776         spidev->speed_hz = spi->max_speed_hz;
 777
 778         if (status == 0)
 779                 spi_set_drvdata(spi, spidev);
 780         else
 781                 kfree(spidev);
 782
 783         return status;
 784 }
 785
 786 static int spidev_remove(struct spi_device *spi)
 787 {
 788         struct spidev_data      *spidev = spi_get_drvdata(spi);
 789
 790         /* make sure ops on existing fds can abort cleanly */
 791         spin_lock_irq(&spidev->spi_lock);
 792         spidev->spi = NULL;
 793         spin_unlock_irq(&spidev->spi_lock);
 794
 795         /* prevent new opens */
 796         mutex_lock(&device_list_lock);
 797         list_del(&spidev->device_entry);
 798         device_destroy(spidev_class, spidev->devt);
 799         clear_bit(MINOR(spidev->devt), minors);
 800         if (spidev->users == 0)
 801                 kfree(spidev);
 802         mutex_unlock(&device_list_lock);
 803
 804         return 0;
 805 }
 806
 807 static struct spi_driver spidev_spi_driver = {
 808         .driver = {
 809                 .name =         "spidev",
 810                 .of_match_table = of_match_ptr(spidev_dt_ids),
 811                 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
 812         },
 813         .probe =        spidev_probe,
 814         .remove =       spidev_remove,
 815
 816         /* NOTE:  suspend/resume methods are not necessary here.
 817          * We don't do anything except pass the requests to/from
 818          * the underlying controller.  The refrigerator handles
 819          * most issues; the controller driver handles the rest.
 820          */
 821 };
 822
 823 /*-------------------------------------------------------------------------*/
 824
 825 static int __init spidev_init(void)
 826 {
 827         int status;
 828
 829         /* Claim our 256 reserved device numbers.  Then register a class
 830          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 831          * the driver which manages those device numbers.
 832          */
 833         BUILD_BUG_ON(N_SPI_MINORS > 256);
 834         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 835         if (status < 0)
 836                 return status;
 837
 838         spidev_class = class_create(THIS_MODULE, "spidev");
 839         if (IS_ERR(spidev_class)) {
 840                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 841                 return PTR_ERR(spidev_class);
 842         }
 843
 844         status = spi_register_driver(&spidev_spi_driver);
 845         if (status < 0) {
 846                 class_destroy(spidev_class);
 847                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 848         }
 849         return status;
 850 }
 851 module_init(spidev_init);
 852
 853 static void __exit spidev_exit(void)
 854 {
 855         spi_unregister_driver(&spidev_spi_driver);
 856         class_destroy(spidev_class);
 857         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 858 }
 859 module_exit(spidev_exit);
 860
 861 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 862 MODULE_DESCRIPTION("User mode SPI device interface");
 863 MODULE_LICENSE("GPL");
 864 MODULE_ALIAS("spi:spidev");