drivers/spi/spidev.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Simple synchronous userspace interface to SPI devices
   4  *
   5  * Copyright (C) 2006 SWAPP
   6  *      Andrea Paterniani <a.paterniani@swapp-eng.it>
   7  * Copyright (C) 2007 David Brownell (simplification, cleanup)
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/ioctl.h>
  13 #include <linux/fs.h>
  14 #include <linux/device.h>
  15 #include <linux/err.h>
  16 #include <linux/list.h>
  17 #include <linux/errno.h>
  18 #include <linux/mutex.h>
  19 #include <linux/slab.h>
  20 #include <linux/compat.h>
  21 #include <linux/of.h>
  22 #include <linux/of_device.h>
  23 #include <linux/acpi.h>
  24
  25 #include <linux/spi/spi.h>
  26 #include <linux/spi/spidev.h>
  27
  28 #include <linux/uaccess.h>
  29
  30
  31 /*
  32  * This supports access to SPI devices using normal userspace I/O calls.
  33  * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
  34  * and often mask message boundaries, full SPI support requires full duplex
  35  * transfers.  There are several kinds of internal message boundaries to
  36  * handle chipselect management and other protocol options.
  37  *
  38  * SPI has a character major number assigned.  We allocate minor numbers
  39  * dynamically using a bitmask.  You must use hotplug tools, such as udev
  40  * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
  41  * nodes, since there is no fixed association of minor numbers with any
  42  * particular SPI bus or device.
  43  */
  44 #define SPIDEV_MAJOR                    153     /* assigned */
  45 #define N_SPI_MINORS                    32      /* ... up to 256 */
  46
  47 static DECLARE_BITMAP(minors, N_SPI_MINORS);
  48
  49
  50 /* Bit masks for spi_device.mode management.  Note that incorrect
  51  * settings for some settings can cause *lots* of trouble for other
  52  * devices on a shared bus:
  53  *
  54  *  - CS_HIGH ... this device will be active when it shouldn't be
  55  *  - 3WIRE ... when active, it won't behave as it should
  56  *  - NO_CS ... there will be no explicit message boundaries; this
  57  *      is completely incompatible with the shared bus model
  58  *  - READY ... transfers may proceed when they shouldn't.
  59  *
  60  * REVISIT should changing those flags be privileged?
  61  */
  62 #define SPI_MODE_MASK           (SPI_MODE_X_MASK | SPI_CS_HIGH \
  63                                 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
  64                                 | SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
  65                                 | SPI_TX_QUAD | SPI_TX_OCTAL | SPI_RX_DUAL \
  66                                 | SPI_RX_QUAD | SPI_RX_OCTAL)
  67
  68 struct spidev_data {
  69         dev_t                   devt;
  70         spinlock_t              spi_lock;
  71         struct spi_device       *spi;
  72         struct list_head        device_entry;
  73
  74         /* TX/RX buffers are NULL unless this device is open (users > 0) */
  75         struct mutex            buf_lock;
  76         unsigned                users;
  77         u8                      *tx_buffer;
  78         u8                      *rx_buffer;
  79         u32                     speed_hz;
  80 };
  81
  82 static LIST_HEAD(device_list);
  83 static DEFINE_MUTEX(device_list_lock);
  84
  85 static unsigned bufsiz = 4096;
  86 module_param(bufsiz, uint, S_IRUGO);
  87 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
  88
  89 /*-------------------------------------------------------------------------*/
  90
  91 static ssize_t
  92 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
  93 {
  94         int status;
  95         struct spi_device *spi;
  96
  97         spin_lock_irq(&spidev->spi_lock);
  98         spi = spidev->spi;
  99         spin_unlock_irq(&spidev->spi_lock);
 100
 101         if (spi == NULL)
 102                 status = -ESHUTDOWN;
 103         else
 104                 status = spi_sync(spi, message);
 105
 106         if (status == 0)
 107                 status = message->actual_length;
 108
 109         return status;
 110 }
 111
 112 static inline ssize_t
 113 spidev_sync_write(struct spidev_data *spidev, size_t len)
 114 {
 115         struct spi_transfer     t = {
 116                         .tx_buf         = spidev->tx_buffer,
 117                         .len            = len,
 118                         .speed_hz       = spidev->speed_hz,
 119                 };
 120         struct spi_message      m;
 121
 122         spi_message_init(&m);
 123         spi_message_add_tail(&t, &m);
 124         return spidev_sync(spidev, &m);
 125 }
 126
 127 static inline ssize_t
 128 spidev_sync_read(struct spidev_data *spidev, size_t len)
 129 {
 130         struct spi_transfer     t = {
 131                         .rx_buf         = spidev->rx_buffer,
 132                         .len            = len,
 133                         .speed_hz       = spidev->speed_hz,
 134                 };
 135         struct spi_message      m;
 136
 137         spi_message_init(&m);
 138         spi_message_add_tail(&t, &m);
 139         return spidev_sync(spidev, &m);
 140 }
 141
 142 /*-------------------------------------------------------------------------*/
 143
 144 /* Read-only message with current device setup */
 145 static ssize_t
 146 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 147 {
 148         struct spidev_data      *spidev;
 149         ssize_t                 status;
 150
 151         /* chipselect only toggles at start or end of operation */
 152         if (count > bufsiz)
 153                 return -EMSGSIZE;
 154
 155         spidev = filp->private_data;
 156
 157         mutex_lock(&spidev->buf_lock);
 158         status = spidev_sync_read(spidev, count);
 159         if (status > 0) {
 160                 unsigned long   missing;
 161
 162                 missing = copy_to_user(buf, spidev->rx_buffer, status);
 163                 if (missing == status)
 164                         status = -EFAULT;
 165                 else
 166                         status = status - missing;
 167         }
 168         mutex_unlock(&spidev->buf_lock);
 169
 170         return status;
 171 }
 172
 173 /* Write-only message with current device setup */
 174 static ssize_t
 175 spidev_write(struct file *filp, const char __user *buf,
 176                 size_t count, loff_t *f_pos)
 177 {
 178         struct spidev_data      *spidev;
 179         ssize_t                 status;
 180         unsigned long           missing;
 181
 182         /* chipselect only toggles at start or end of operation */
 183         if (count > bufsiz)
 184                 return -EMSGSIZE;
 185
 186         spidev = filp->private_data;
 187
 188         mutex_lock(&spidev->buf_lock);
 189         missing = copy_from_user(spidev->tx_buffer, buf, count);
 190         if (missing == 0)
 191                 status = spidev_sync_write(spidev, count);
 192         else
 193                 status = -EFAULT;
 194         mutex_unlock(&spidev->buf_lock);
 195
 196         return status;
 197 }
 198
 199 static int spidev_message(struct spidev_data *spidev,
 200                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 201 {
 202         struct spi_message      msg;
 203         struct spi_transfer     *k_xfers;
 204         struct spi_transfer     *k_tmp;
 205         struct spi_ioc_transfer *u_tmp;
 206         unsigned                n, total, tx_total, rx_total;
 207         u8                      *tx_buf, *rx_buf;
 208         int                     status = -EFAULT;
 209
 210         spi_message_init(&msg);
 211         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 212         if (k_xfers == NULL)
 213                 return -ENOMEM;
 214
 215         /* Construct spi_message, copying any tx data to bounce buffer.
 216          * We walk the array of user-provided transfers, using each one
 217          * to initialize a kernel version of the same transfer.
 218          */
 219         tx_buf = spidev->tx_buffer;
 220         rx_buf = spidev->rx_buffer;
 221         total = 0;
 222         tx_total = 0;
 223         rx_total = 0;
 224         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 225                         n;
 226                         n--, k_tmp++, u_tmp++) {
 227                 /* Ensure that also following allocations from rx_buf/tx_buf will meet
 228                  * DMA alignment requirements.
 229                  */
 230                 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN);
 231
 232                 k_tmp->len = u_tmp->len;
 233
 234                 total += k_tmp->len;
 235                 /* Since the function returns the total length of transfers
 236                  * on success, restrict the total to positive int values to
 237                  * avoid the return value looking like an error.  Also check
 238                  * each transfer length to avoid arithmetic overflow.
 239                  */
 240                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 241                         status = -EMSGSIZE;
 242                         goto done;
 243                 }
 244
 245                 if (u_tmp->rx_buf) {
 246                         /* this transfer needs space in RX bounce buffer */
 247                         rx_total += len_aligned;
 248                         if (rx_total > bufsiz) {
 249                                 status = -EMSGSIZE;
 250                                 goto done;
 251                         }
 252                         k_tmp->rx_buf = rx_buf;
 253                         rx_buf += len_aligned;
 254                 }
 255                 if (u_tmp->tx_buf) {
 256                         /* this transfer needs space in TX bounce buffer */
 257                         tx_total += len_aligned;
 258                         if (tx_total > bufsiz) {
 259                                 status = -EMSGSIZE;
 260                                 goto done;
 261                         }
 262                         k_tmp->tx_buf = tx_buf;
 263                         if (copy_from_user(tx_buf, (const u8 __user *)
 264                                                 (uintptr_t) u_tmp->tx_buf,
 265                                         u_tmp->len))
 266                                 goto done;
 267                         tx_buf += len_aligned;
 268                 }
 269
 270                 k_tmp->cs_change = !!u_tmp->cs_change;
 271                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 272                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 273                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 274                 k_tmp->delay.value = u_tmp->delay_usecs;
 275                 k_tmp->delay.unit = SPI_DELAY_UNIT_USECS;
 276                 k_tmp->speed_hz = u_tmp->speed_hz;
 277                 k_tmp->word_delay.value = u_tmp->word_delay_usecs;
 278                 k_tmp->word_delay.unit = SPI_DELAY_UNIT_USECS;
 279                 if (!k_tmp->speed_hz)
 280                         k_tmp->speed_hz = spidev->speed_hz;
 281 #ifdef VERBOSE
 282                 dev_dbg(&spidev->spi->dev,
 283                         "  xfer len %u %s%s%s%dbits %u usec %u usec %uHz\n",
 284                         k_tmp->len,
 285                         k_tmp->rx_buf ? "rx " : "",
 286                         k_tmp->tx_buf ? "tx " : "",
 287                         k_tmp->cs_change ? "cs " : "",
 288                         k_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 289                         k_tmp->delay.value,
 290                         k_tmp->word_delay.value,
 291                         k_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 292 #endif
 293                 spi_message_add_tail(k_tmp, &msg);
 294         }
 295
 296         status = spidev_sync(spidev, &msg);
 297         if (status < 0)
 298                 goto done;
 299
 300         /* copy any rx data out of bounce buffer */
 301         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 302                         n;
 303                         n--, k_tmp++, u_tmp++) {
 304                 if (u_tmp->rx_buf) {
 305                         if (copy_to_user((u8 __user *)
 306                                         (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
 307                                         u_tmp->len)) {
 308                                 status = -EFAULT;
 309                                 goto done;
 310                         }
 311                 }
 312         }
 313         status = total;
 314
 315 done:
 316         kfree(k_xfers);
 317         return status;
 318 }
 319
 320 static struct spi_ioc_transfer *
 321 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 322                 unsigned *n_ioc)
 323 {
 324         u32     tmp;
 325
 326         /* Check type, command number and direction */
 327         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 328                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 329                         || _IOC_DIR(cmd) != _IOC_WRITE)
 330                 return ERR_PTR(-ENOTTY);
 331
 332         tmp = _IOC_SIZE(cmd);
 333         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 334                 return ERR_PTR(-EINVAL);
 335         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 336         if (*n_ioc == 0)
 337                 return NULL;
 338
 339         /* copy into scratch area */
 340         return memdup_user(u_ioc, tmp);
 341 }
 342
 343 static long
 344 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 345 {
 346         int                     retval = 0;
 347         struct spidev_data      *spidev;
 348         struct spi_device       *spi;
 349         u32                     tmp;
 350         unsigned                n_ioc;
 351         struct spi_ioc_transfer *ioc;
 352
 353         /* Check type and command number */
 354         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 355                 return -ENOTTY;
 356
 357         /* guard against device removal before, or while,
 358          * we issue this ioctl.
 359          */
 360         spidev = filp->private_data;
 361         spin_lock_irq(&spidev->spi_lock);
 362         spi = spi_dev_get(spidev->spi);
 363         spin_unlock_irq(&spidev->spi_lock);
 364
 365         if (spi == NULL)
 366                 return -ESHUTDOWN;
 367
 368         /* use the buffer lock here for triple duty:
 369          *  - prevent I/O (from us) so calling spi_setup() is safe;
 370          *  - prevent concurrent SPI_IOC_WR_* from morphing
 371          *    data fields while SPI_IOC_RD_* reads them;
 372          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 373          */
 374         mutex_lock(&spidev->buf_lock);
 375
 376         switch (cmd) {
 377         /* read requests */
 378         case SPI_IOC_RD_MODE:
 379         case SPI_IOC_RD_MODE32:
 380                 tmp = spi->mode;
 381
 382                 {
 383                         struct spi_controller *ctlr = spi->controller;
 384
 385                         if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
 386                             ctlr->cs_gpiods[spi->chip_select])
 387                                 tmp &= ~SPI_CS_HIGH;
 388                 }
 389
 390                 if (cmd == SPI_IOC_RD_MODE)
 391                         retval = put_user(tmp & SPI_MODE_MASK,
 392                                           (__u8 __user *)arg);
 393                 else
 394                         retval = put_user(tmp & SPI_MODE_MASK,
 395                                           (__u32 __user *)arg);
 396                 break;
 397         case SPI_IOC_RD_LSB_FIRST:
 398                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 399                                         (__u8 __user *)arg);
 400                 break;
 401         case SPI_IOC_RD_BITS_PER_WORD:
 402                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 403                 break;
 404         case SPI_IOC_RD_MAX_SPEED_HZ:
 405                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 406                 break;
 407
 408         /* write requests */
 409         case SPI_IOC_WR_MODE:
 410         case SPI_IOC_WR_MODE32:
 411                 if (cmd == SPI_IOC_WR_MODE)
 412                         retval = get_user(tmp, (u8 __user *)arg);
 413                 else
 414                         retval = get_user(tmp, (u32 __user *)arg);
 415                 if (retval == 0) {
 416                         u32     save = spi->mode;
 417
 418                         if (tmp & ~SPI_MODE_MASK) {
 419                                 retval = -EINVAL;
 420                                 break;
 421                         }
 422
 423                         tmp |= spi->mode & ~SPI_MODE_MASK;
 424                         spi->mode = (u16)tmp;
 425                         retval = spi_setup(spi);
 426                         if (retval < 0)
 427                                 spi->mode = save;
 428                         else
 429                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 430                 }
 431                 break;
 432         case SPI_IOC_WR_LSB_FIRST:
 433                 retval = get_user(tmp, (__u8 __user *)arg);
 434                 if (retval == 0) {
 435                         u32     save = spi->mode;
 436
 437                         if (tmp)
 438                                 spi->mode |= SPI_LSB_FIRST;
 439                         else
 440                                 spi->mode &= ~SPI_LSB_FIRST;
 441                         retval = spi_setup(spi);
 442                         if (retval < 0)
 443                                 spi->mode = save;
 444                         else
 445                                 dev_dbg(&spi->dev, "%csb first\n",
 446                                                 tmp ? 'l' : 'm');
 447                 }
 448                 break;
 449         case SPI_IOC_WR_BITS_PER_WORD:
 450                 retval = get_user(tmp, (__u8 __user *)arg);
 451                 if (retval == 0) {
 452                         u8      save = spi->bits_per_word;
 453
 454                         spi->bits_per_word = tmp;
 455                         retval = spi_setup(spi);
 456                         if (retval < 0)
 457                                 spi->bits_per_word = save;
 458                         else
 459                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 460                 }
 461                 break;
 462         case SPI_IOC_WR_MAX_SPEED_HZ:
 463                 retval = get_user(tmp, (__u32 __user *)arg);
 464                 if (retval == 0) {
 465                         u32     save = spi->max_speed_hz;
 466
 467                         spi->max_speed_hz = tmp;
 468                         retval = spi_setup(spi);
 469                         if (retval == 0) {
 470                                 spidev->speed_hz = tmp;
 471                                 dev_dbg(&spi->dev, "%d Hz (max)\n",
 472                                         spidev->speed_hz);
 473                         }
 474                         spi->max_speed_hz = save;
 475                 }
 476                 break;
 477
 478         default:
 479                 /* segmented and/or full-duplex I/O request */
 480                 /* Check message and copy into scratch area */
 481                 ioc = spidev_get_ioc_message(cmd,
 482                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 483                 if (IS_ERR(ioc)) {
 484                         retval = PTR_ERR(ioc);
 485                         break;
 486                 }
 487                 if (!ioc)
 488                         break;  /* n_ioc is also 0 */
 489
 490                 /* translate to spi_message, execute */
 491                 retval = spidev_message(spidev, ioc, n_ioc);
 492                 kfree(ioc);
 493                 break;
 494         }
 495
 496         mutex_unlock(&spidev->buf_lock);
 497         spi_dev_put(spi);
 498         return retval;
 499 }
 500
 501 #ifdef CONFIG_COMPAT
 502 static long
 503 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 504                 unsigned long arg)
 505 {
 506         struct spi_ioc_transfer __user  *u_ioc;
 507         int                             retval = 0;
 508         struct spidev_data              *spidev;
 509         struct spi_device               *spi;
 510         unsigned                        n_ioc, n;
 511         struct spi_ioc_transfer         *ioc;
 512
 513         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 514
 515         /* guard against device removal before, or while,
 516          * we issue this ioctl.
 517          */
 518         spidev = filp->private_data;
 519         spin_lock_irq(&spidev->spi_lock);
 520         spi = spi_dev_get(spidev->spi);
 521         spin_unlock_irq(&spidev->spi_lock);
 522
 523         if (spi == NULL)
 524                 return -ESHUTDOWN;
 525
 526         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 527         mutex_lock(&spidev->buf_lock);
 528
 529         /* Check message and copy into scratch area */
 530         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 531         if (IS_ERR(ioc)) {
 532                 retval = PTR_ERR(ioc);
 533                 goto done;
 534         }
 535         if (!ioc)
 536                 goto done;      /* n_ioc is also 0 */
 537
 538         /* Convert buffer pointers */
 539         for (n = 0; n < n_ioc; n++) {
 540                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 541                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 542         }
 543
 544         /* translate to spi_message, execute */
 545         retval = spidev_message(spidev, ioc, n_ioc);
 546         kfree(ioc);
 547
 548 done:
 549         mutex_unlock(&spidev->buf_lock);
 550         spi_dev_put(spi);
 551         return retval;
 552 }
 553
 554 static long
 555 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 556 {
 557         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 558                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 559                         && _IOC_DIR(cmd) == _IOC_WRITE)
 560                 return spidev_compat_ioc_message(filp, cmd, arg);
 561
 562         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 563 }
 564 #else
 565 #define spidev_compat_ioctl NULL
 566 #endif /* CONFIG_COMPAT */
 567
 568 static int spidev_open(struct inode *inode, struct file *filp)
 569 {
 570         struct spidev_data      *spidev;
 571         int                     status = -ENXIO;
 572
 573         mutex_lock(&device_list_lock);
 574
 575         list_for_each_entry(spidev, &device_list, device_entry) {
 576                 if (spidev->devt == inode->i_rdev) {
 577                         status = 0;
 578                         break;
 579                 }
 580         }
 581
 582         if (status) {
 583                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 584                 goto err_find_dev;
 585         }
 586
 587         if (!spidev->tx_buffer) {
 588                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 589                 if (!spidev->tx_buffer) {
 590                         status = -ENOMEM;
 591                         goto err_find_dev;
 592                 }
 593         }
 594
 595         if (!spidev->rx_buffer) {
 596                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 597                 if (!spidev->rx_buffer) {
 598                         status = -ENOMEM;
 599                         goto err_alloc_rx_buf;
 600                 }
 601         }
 602
 603         spidev->users++;
 604         filp->private_data = spidev;
 605         stream_open(inode, filp);
 606
 607         mutex_unlock(&device_list_lock);
 608         return 0;
 609
 610 err_alloc_rx_buf:
 611         kfree(spidev->tx_buffer);
 612         spidev->tx_buffer = NULL;
 613 err_find_dev:
 614         mutex_unlock(&device_list_lock);
 615         return status;
 616 }
 617
 618 static int spidev_release(struct inode *inode, struct file *filp)
 619 {
 620         struct spidev_data      *spidev;
 621         int                     dofree;
 622
 623         mutex_lock(&device_list_lock);
 624         spidev = filp->private_data;
 625         filp->private_data = NULL;
 626
 627         spin_lock_irq(&spidev->spi_lock);
 628         /* ... after we unbound from the underlying device? */
 629         dofree = (spidev->spi == NULL);
 630         spin_unlock_irq(&spidev->spi_lock);
 631
 632         /* last close? */
 633         spidev->users--;
 634         if (!spidev->users) {
 635
 636                 kfree(spidev->tx_buffer);
 637                 spidev->tx_buffer = NULL;
 638
 639                 kfree(spidev->rx_buffer);
 640                 spidev->rx_buffer = NULL;
 641
 642                 if (dofree)
 643                         kfree(spidev);
 644                 else
 645                         spidev->speed_hz = spidev->spi->max_speed_hz;
 646         }
 647 #ifdef CONFIG_SPI_SLAVE
 648         if (!dofree)
 649                 spi_slave_abort(spidev->spi);
 650 #endif
 651         mutex_unlock(&device_list_lock);
 652
 653         return 0;
 654 }
 655
 656 static const struct file_operations spidev_fops = {
 657         .owner =        THIS_MODULE,
 658         /* REVISIT switch to aio primitives, so that userspace
 659          * gets more complete API coverage.  It'll simplify things
 660          * too, except for the locking.
 661          */
 662         .write =        spidev_write,
 663         .read =         spidev_read,
 664         .unlocked_ioctl = spidev_ioctl,
 665         .compat_ioctl = spidev_compat_ioctl,
 666         .open =         spidev_open,
 667         .release =      spidev_release,
 668         .llseek =       no_llseek,
 669 };
 670
 671 /*-------------------------------------------------------------------------*/
 672
 673 /* The main reason to have this class is to make mdev/udev create the
 674  * /dev/spidevB.C character device nodes exposing our userspace API.
 675  * It also simplifies memory management.
 676  */
 677
 678 static struct class *spidev_class;
 679
 680 static const struct spi_device_id spidev_spi_ids[] = {
 681         { .name = "spidev" },
 682         { .name = "dh2228fv" },
 683         { .name = "ltc2488" },
 684         { .name = "sx1301" },
 685         { .name = "bk4" },
 686         { .name = "dhcom-board" },
 687         { .name = "m53cpld" },
 688         { .name = "spi-petra" },
 689         { .name = "spi-authenta" },
 690         {},
 691 };
 692 MODULE_DEVICE_TABLE(spi, spidev_spi_ids);
 693
 694 #ifdef CONFIG_OF
 695 static const struct of_device_id spidev_dt_ids[] = {
 696         { .compatible = "rohm,dh2228fv" },
 697         { .compatible = "lineartechnology,ltc2488" },
 698         { .compatible = "semtech,sx1301" },
 699         { .compatible = "lwn,bk4" },
 700         { .compatible = "dh,dhcom-board" },
 701         { .compatible = "menlo,m53cpld" },
 702         { .compatible = "cisco,spi-petra" },
 703         { .compatible = "micron,spi-authenta" },
 704         {},
 705 };
 706 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 707 #endif
 708
 709 #ifdef CONFIG_ACPI
 710
 711 /* Dummy SPI devices not to be used in production systems */
 712 #define SPIDEV_ACPI_DUMMY       1
 713
 714 static const struct acpi_device_id spidev_acpi_ids[] = {
 715         /*
 716          * The ACPI SPT000* devices are only meant for development and
 717          * testing. Systems used in production should have a proper ACPI
 718          * description of the connected peripheral and they should also use
 719          * a proper driver instead of poking directly to the SPI bus.
 720          */
 721         { "SPT0001", SPIDEV_ACPI_DUMMY },
 722         { "SPT0002", SPIDEV_ACPI_DUMMY },
 723         { "SPT0003", SPIDEV_ACPI_DUMMY },
 724         {},
 725 };
 726 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 727
 728 static void spidev_probe_acpi(struct spi_device *spi)
 729 {
 730         const struct acpi_device_id *id;
 731
 732         if (!has_acpi_companion(&spi->dev))
 733                 return;
 734
 735         id = acpi_match_device(spidev_acpi_ids, &spi->dev);
 736         if (WARN_ON(!id))
 737                 return;
 738
 739         if (id->driver_data == SPIDEV_ACPI_DUMMY)
 740                 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
 741 }
 742 #else
 743 static inline void spidev_probe_acpi(struct spi_device *spi) {}
 744 #endif
 745
 746 /*-------------------------------------------------------------------------*/
 747
 748 static int spidev_probe(struct spi_device *spi)
 749 {
 750         struct spidev_data      *spidev;
 751         int                     status;
 752         unsigned long           minor;
 753
 754         /*
 755          * spidev should never be referenced in DT without a specific
 756          * compatible string, it is a Linux implementation thing
 757          * rather than a description of the hardware.
 758          */
 759         WARN(0 && spi->dev.of_node &&
 760              of_device_is_compatible(spi->dev.of_node, "spidev"),
 761              "%pOF: buggy DT: spidev listed directly in DT\n", spi->dev.of_node);
 762
 763         spidev_probe_acpi(spi);
 764
 765         /* Allocate driver data */
 766         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 767         if (!spidev)
 768                 return -ENOMEM;
 769
 770         /* Initialize the driver data */
 771         spidev->spi = spi;
 772         spin_lock_init(&spidev->spi_lock);
 773         mutex_init(&spidev->buf_lock);
 774
 775         INIT_LIST_HEAD(&spidev->device_entry);
 776
 777         /* If we can allocate a minor number, hook up this device.
 778          * Reusing minors is fine so long as udev or mdev is working.
 779          */
 780         mutex_lock(&device_list_lock);
 781         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 782         if (minor < N_SPI_MINORS) {
 783                 struct device *dev;
 784
 785                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 786                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 787                                     spidev, "spidev%d.%d",
 788                                     spi->master->bus_num, spi->chip_select);
 789                 status = PTR_ERR_OR_ZERO(dev);
 790         } else {
 791                 dev_dbg(&spi->dev, "no minor number available!\n");
 792                 status = -ENODEV;
 793         }
 794         if (status == 0) {
 795                 set_bit(minor, minors);
 796                 list_add(&spidev->device_entry, &device_list);
 797         }
 798         mutex_unlock(&device_list_lock);
 799
 800         spidev->speed_hz = spi->max_speed_hz;
 801
 802         if (status == 0)
 803                 spi_set_drvdata(spi, spidev);
 804         else
 805                 kfree(spidev);
 806
 807         return status;
 808 }
 809
 810 static int spidev_remove(struct spi_device *spi)
 811 {
 812         struct spidev_data      *spidev = spi_get_drvdata(spi);
 813
 814         /* prevent new opens */
 815         mutex_lock(&device_list_lock);
 816         /* make sure ops on existing fds can abort cleanly */
 817         spin_lock_irq(&spidev->spi_lock);
 818         spidev->spi = NULL;
 819         spin_unlock_irq(&spidev->spi_lock);
 820
 821         list_del(&spidev->device_entry);
 822         device_destroy(spidev_class, spidev->devt);
 823         clear_bit(MINOR(spidev->devt), minors);
 824         if (spidev->users == 0)
 825                 kfree(spidev);
 826         mutex_unlock(&device_list_lock);
 827
 828         return 0;
 829 }
 830
 831 static struct spi_driver spidev_spi_driver = {
 832         .driver = {
 833                 .name =         "spidev",
 834                 .of_match_table = of_match_ptr(spidev_dt_ids),
 835                 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
 836         },
 837         .probe =        spidev_probe,
 838         .remove =       spidev_remove,
 839         .id_table =     spidev_spi_ids,
 840
 841         /* NOTE:  suspend/resume methods are not necessary here.
 842          * We don't do anything except pass the requests to/from
 843          * the underlying controller.  The refrigerator handles
 844          * most issues; the controller driver handles the rest.
 845          */
 846 };
 847
 848 /*-------------------------------------------------------------------------*/
 849
 850 static int __init spidev_init(void)
 851 {
 852         int status;
 853
 854         /* Claim our 256 reserved device numbers.  Then register a class
 855          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 856          * the driver which manages those device numbers.
 857          */
 858         BUILD_BUG_ON(N_SPI_MINORS > 256);
 859         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 860         if (status < 0)
 861                 return status;
 862
 863         spidev_class = class_create(THIS_MODULE, "spidev");
 864         if (IS_ERR(spidev_class)) {
 865                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 866                 return PTR_ERR(spidev_class);
 867         }
 868
 869         status = spi_register_driver(&spidev_spi_driver);
 870         if (status < 0) {
 871                 class_destroy(spidev_class);
 872                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 873         }
 874         return status;
 875 }
 876 module_init(spidev_init);
 877
 878 static void __exit spidev_exit(void)
 879 {
 880         spi_unregister_driver(&spidev_spi_driver);
 881         class_destroy(spidev_class);
 882         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 883 }
 884 module_exit(spidev_exit);
 885
 886 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 887 MODULE_DESCRIPTION("User mode SPI device interface");
 888 MODULE_LICENSE("GPL");
 889 MODULE_ALIAS("spi:spidev");