drivers/spi/spidev.c

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