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                 /* Ensure that also following allocations from rx_buf/tx_buf will meet
 236                  * DMA alignment requirements.
 237                  */
 238                 unsigned int len_aligned = ALIGN(u_tmp->len, ARCH_KMALLOC_MINALIGN);
 239
 240                 k_tmp->len = u_tmp->len;
 241
 242                 total += k_tmp->len;
 243                 /* Since the function returns the total length of transfers
 244                  * on success, restrict the total to positive int values to
 245                  * avoid the return value looking like an error.  Also check
 246                  * each transfer length to avoid arithmetic overflow.
 247                  */
 248                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 249                         status = -EMSGSIZE;
 250                         goto done;
 251                 }
 252
 253                 if (u_tmp->rx_buf) {
 254                         /* this transfer needs space in RX bounce buffer */
 255                         rx_total += len_aligned;
 256                         if (rx_total > bufsiz) {
 257                                 status = -EMSGSIZE;
 258                                 goto done;
 259                         }
 260                         k_tmp->rx_buf = rx_buf;
 261                         rx_buf += len_aligned;
 262                 }
 263                 if (u_tmp->tx_buf) {
 264                         /* this transfer needs space in TX bounce buffer */
 265                         tx_total += len_aligned;
 266                         if (tx_total > bufsiz) {
 267                                 status = -EMSGSIZE;
 268                                 goto done;
 269                         }
 270                         k_tmp->tx_buf = tx_buf;
 271                         if (copy_from_user(tx_buf, (const u8 __user *)
 272                                                 (uintptr_t) u_tmp->tx_buf,
 273                                         u_tmp->len))
 274                                 goto done;
 275                         tx_buf += len_aligned;
 276                 }
 277
 278                 k_tmp->cs_change = !!u_tmp->cs_change;
 279                 k_tmp->tx_nbits = u_tmp->tx_nbits;
 280                 k_tmp->rx_nbits = u_tmp->rx_nbits;
 281                 k_tmp->bits_per_word = u_tmp->bits_per_word;
 282                 k_tmp->delay_usecs = u_tmp->delay_usecs;
 283                 k_tmp->speed_hz = u_tmp->speed_hz;
 284                 if (!k_tmp->speed_hz)
 285                         k_tmp->speed_hz = spidev->speed_hz;
 286 #ifdef VERBOSE
 287                 dev_dbg(&spidev->spi->dev,
 288                         "  xfer len %u %s%s%s%dbits %u usec %uHz\n",
 289                         u_tmp->len,
 290                         u_tmp->rx_buf ? "rx " : "",
 291                         u_tmp->tx_buf ? "tx " : "",
 292                         u_tmp->cs_change ? "cs " : "",
 293                         u_tmp->bits_per_word ? : spidev->spi->bits_per_word,
 294                         u_tmp->delay_usecs,
 295                         u_tmp->speed_hz ? : spidev->spi->max_speed_hz);
 296 #endif
 297                 spi_message_add_tail(k_tmp, &msg);
 298         }
 299
 300         status = spidev_sync(spidev, &msg);
 301         if (status < 0)
 302                 goto done;
 303
 304         /* copy any rx data out of bounce buffer */
 305         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 306                         n;
 307                         n--, k_tmp++, u_tmp++) {
 308                 if (u_tmp->rx_buf) {
 309                         if (copy_to_user((u8 __user *)
 310                                         (uintptr_t) u_tmp->rx_buf, k_tmp->rx_buf,
 311                                         u_tmp->len)) {
 312                                 status = -EFAULT;
 313                                 goto done;
 314                         }
 315                 }
 316         }
 317         status = total;
 318
 319 done:
 320         kfree(k_xfers);
 321         return status;
 322 }
 323
 324 static struct spi_ioc_transfer *
 325 spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
 326                 unsigned *n_ioc)
 327 {
 328         u32     tmp;
 329
 330         /* Check type, command number and direction */
 331         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 332                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 333                         || _IOC_DIR(cmd) != _IOC_WRITE)
 334                 return ERR_PTR(-ENOTTY);
 335
 336         tmp = _IOC_SIZE(cmd);
 337         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 338                 return ERR_PTR(-EINVAL);
 339         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 340         if (*n_ioc == 0)
 341                 return NULL;
 342
 343         /* copy into scratch area */
 344         return memdup_user(u_ioc, tmp);
 345 }
 346
 347 static long
 348 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 349 {
 350         int                     retval = 0;
 351         struct spidev_data      *spidev;
 352         struct spi_device       *spi;
 353         u32                     tmp;
 354         unsigned                n_ioc;
 355         struct spi_ioc_transfer *ioc;
 356
 357         /* Check type and command number */
 358         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 359                 return -ENOTTY;
 360
 361         /* guard against device removal before, or while,
 362          * we issue this ioctl.
 363          */
 364         spidev = filp->private_data;
 365         spin_lock_irq(&spidev->spi_lock);
 366         spi = spi_dev_get(spidev->spi);
 367         spin_unlock_irq(&spidev->spi_lock);
 368
 369         if (spi == NULL)
 370                 return -ESHUTDOWN;
 371
 372         /* use the buffer lock here for triple duty:
 373          *  - prevent I/O (from us) so calling spi_setup() is safe;
 374          *  - prevent concurrent SPI_IOC_WR_* from morphing
 375          *    data fields while SPI_IOC_RD_* reads them;
 376          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 377          */
 378         mutex_lock(&spidev->buf_lock);
 379
 380         switch (cmd) {
 381         /* read requests */
 382         case SPI_IOC_RD_MODE:
 383                 retval = put_user(spi->mode & SPI_MODE_MASK,
 384                                         (__u8 __user *)arg);
 385                 break;
 386         case SPI_IOC_RD_MODE32:
 387                 retval = put_user(spi->mode & SPI_MODE_MASK,
 388                                         (__u32 __user *)arg);
 389                 break;
 390         case SPI_IOC_RD_LSB_FIRST:
 391                 retval = put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 392                                         (__u8 __user *)arg);
 393                 break;
 394         case SPI_IOC_RD_BITS_PER_WORD:
 395                 retval = put_user(spi->bits_per_word, (__u8 __user *)arg);
 396                 break;
 397         case SPI_IOC_RD_MAX_SPEED_HZ:
 398                 retval = put_user(spidev->speed_hz, (__u32 __user *)arg);
 399                 break;
 400
 401         /* write requests */
 402         case SPI_IOC_WR_MODE:
 403         case SPI_IOC_WR_MODE32:
 404                 if (cmd == SPI_IOC_WR_MODE)
 405                         retval = get_user(tmp, (u8 __user *)arg);
 406                 else
 407                         retval = get_user(tmp, (u32 __user *)arg);
 408                 if (retval == 0) {
 409                         u32     save = spi->mode;
 410
 411                         if (tmp & ~SPI_MODE_MASK) {
 412                                 retval = -EINVAL;
 413                                 break;
 414                         }
 415
 416                         tmp |= spi->mode & ~SPI_MODE_MASK;
 417                         spi->mode = (u16)tmp;
 418                         retval = spi_setup(spi);
 419                         if (retval < 0)
 420                                 spi->mode = save;
 421                         else
 422                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 423                 }
 424                 break;
 425         case SPI_IOC_WR_LSB_FIRST:
 426                 retval = get_user(tmp, (__u8 __user *)arg);
 427                 if (retval == 0) {
 428                         u32     save = spi->mode;
 429
 430                         if (tmp)
 431                                 spi->mode |= SPI_LSB_FIRST;
 432                         else
 433                                 spi->mode &= ~SPI_LSB_FIRST;
 434                         retval = spi_setup(spi);
 435                         if (retval < 0)
 436                                 spi->mode = save;
 437                         else
 438                                 dev_dbg(&spi->dev, "%csb first\n",
 439                                                 tmp ? 'l' : 'm');
 440                 }
 441                 break;
 442         case SPI_IOC_WR_BITS_PER_WORD:
 443                 retval = get_user(tmp, (__u8 __user *)arg);
 444                 if (retval == 0) {
 445                         u8      save = spi->bits_per_word;
 446
 447                         spi->bits_per_word = tmp;
 448                         retval = spi_setup(spi);
 449                         if (retval < 0)
 450                                 spi->bits_per_word = save;
 451                         else
 452                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 453                 }
 454                 break;
 455         case SPI_IOC_WR_MAX_SPEED_HZ:
 456                 retval = get_user(tmp, (__u32 __user *)arg);
 457                 if (retval == 0) {
 458                         u32     save = spi->max_speed_hz;
 459
 460                         spi->max_speed_hz = tmp;
 461                         retval = spi_setup(spi);
 462                         if (retval >= 0)
 463                                 spidev->speed_hz = tmp;
 464                         else
 465                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 466                         spi->max_speed_hz = save;
 467                 }
 468                 break;
 469
 470         default:
 471                 /* segmented and/or full-duplex I/O request */
 472                 /* Check message and copy into scratch area */
 473                 ioc = spidev_get_ioc_message(cmd,
 474                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 475                 if (IS_ERR(ioc)) {
 476                         retval = PTR_ERR(ioc);
 477                         break;
 478                 }
 479                 if (!ioc)
 480                         break;  /* n_ioc is also 0 */
 481
 482                 /* translate to spi_message, execute */
 483                 retval = spidev_message(spidev, ioc, n_ioc);
 484                 kfree(ioc);
 485                 break;
 486         }
 487
 488         mutex_unlock(&spidev->buf_lock);
 489         spi_dev_put(spi);
 490         return retval;
 491 }
 492
 493 #ifdef CONFIG_COMPAT
 494 static long
 495 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 496                 unsigned long arg)
 497 {
 498         struct spi_ioc_transfer __user  *u_ioc;
 499         int                             retval = 0;
 500         struct spidev_data              *spidev;
 501         struct spi_device               *spi;
 502         unsigned                        n_ioc, n;
 503         struct spi_ioc_transfer         *ioc;
 504
 505         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 506
 507         /* guard against device removal before, or while,
 508          * we issue this ioctl.
 509          */
 510         spidev = filp->private_data;
 511         spin_lock_irq(&spidev->spi_lock);
 512         spi = spi_dev_get(spidev->spi);
 513         spin_unlock_irq(&spidev->spi_lock);
 514
 515         if (spi == NULL)
 516                 return -ESHUTDOWN;
 517
 518         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 519         mutex_lock(&spidev->buf_lock);
 520
 521         /* Check message and copy into scratch area */
 522         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 523         if (IS_ERR(ioc)) {
 524                 retval = PTR_ERR(ioc);
 525                 goto done;
 526         }
 527         if (!ioc)
 528                 goto done;      /* n_ioc is also 0 */
 529
 530         /* Convert buffer pointers */
 531         for (n = 0; n < n_ioc; n++) {
 532                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 533                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 534         }
 535
 536         /* translate to spi_message, execute */
 537         retval = spidev_message(spidev, ioc, n_ioc);
 538         kfree(ioc);
 539
 540 done:
 541         mutex_unlock(&spidev->buf_lock);
 542         spi_dev_put(spi);
 543         return retval;
 544 }
 545
 546 static long
 547 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 548 {
 549         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 550                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 551                         && _IOC_DIR(cmd) == _IOC_WRITE)
 552                 return spidev_compat_ioc_message(filp, cmd, arg);
 553
 554         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 555 }
 556 #else
 557 #define spidev_compat_ioctl NULL
 558 #endif /* CONFIG_COMPAT */
 559
 560 static int spidev_open(struct inode *inode, struct file *filp)
 561 {
 562         struct spidev_data      *spidev;
 563         int                     status = -ENXIO;
 564
 565         mutex_lock(&device_list_lock);
 566
 567         list_for_each_entry(spidev, &device_list, device_entry) {
 568                 if (spidev->devt == inode->i_rdev) {
 569                         status = 0;
 570                         break;
 571                 }
 572         }
 573
 574         if (status) {
 575                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 576                 goto err_find_dev;
 577         }
 578
 579         if (!spidev->tx_buffer) {
 580                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 581                 if (!spidev->tx_buffer) {
 582                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 583                         status = -ENOMEM;
 584                         goto err_find_dev;
 585                 }
 586         }
 587
 588         if (!spidev->rx_buffer) {
 589                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 590                 if (!spidev->rx_buffer) {
 591                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 592                         status = -ENOMEM;
 593                         goto err_alloc_rx_buf;
 594                 }
 595         }
 596
 597         spidev->users++;
 598         filp->private_data = spidev;
 599         nonseekable_open(inode, filp);
 600
 601         mutex_unlock(&device_list_lock);
 602         return 0;
 603
 604 err_alloc_rx_buf:
 605         kfree(spidev->tx_buffer);
 606         spidev->tx_buffer = NULL;
 607 err_find_dev:
 608         mutex_unlock(&device_list_lock);
 609         return status;
 610 }
 611
 612 static int spidev_release(struct inode *inode, struct file *filp)
 613 {
 614         struct spidev_data      *spidev;
 615         int                     dofree;
 616
 617         mutex_lock(&device_list_lock);
 618         spidev = filp->private_data;
 619         filp->private_data = NULL;
 620
 621         spin_lock_irq(&spidev->spi_lock);
 622         /* ... after we unbound from the underlying device? */
 623         dofree = (spidev->spi == NULL);
 624         spin_unlock_irq(&spidev->spi_lock);
 625
 626         /* last close? */
 627         spidev->users--;
 628         if (!spidev->users) {
 629
 630                 kfree(spidev->tx_buffer);
 631                 spidev->tx_buffer = NULL;
 632
 633                 kfree(spidev->rx_buffer);
 634                 spidev->rx_buffer = NULL;
 635
 636                 if (dofree)
 637                         kfree(spidev);
 638                 else
 639                         spidev->speed_hz = spidev->spi->max_speed_hz;
 640         }
 641 #ifdef CONFIG_SPI_SLAVE
 642         if (!dofree)
 643                 spi_slave_abort(spidev->spi);
 644 #endif
 645         mutex_unlock(&device_list_lock);
 646
 647         return 0;
 648 }
 649
 650 static const struct file_operations spidev_fops = {
 651         .owner =        THIS_MODULE,
 652         /* REVISIT switch to aio primitives, so that userspace
 653          * gets more complete API coverage.  It'll simplify things
 654          * too, except for the locking.
 655          */
 656         .write =        spidev_write,
 657         .read =         spidev_read,
 658         .unlocked_ioctl = spidev_ioctl,
 659         .compat_ioctl = spidev_compat_ioctl,
 660         .open =         spidev_open,
 661         .release =      spidev_release,
 662         .llseek =       no_llseek,
 663 };
 664
 665 /*-------------------------------------------------------------------------*/
 666
 667 /* The main reason to have this class is to make mdev/udev create the
 668  * /dev/spidevB.C character device nodes exposing our userspace API.
 669  * It also simplifies memory management.
 670  */
 671
 672 static struct class *spidev_class;
 673
 674 #ifdef CONFIG_OF
 675 static const struct of_device_id spidev_dt_ids[] = {
 676         { .compatible = "rohm,dh2228fv" },
 677         { .compatible = "lineartechnology,ltc2488" },
 678         { .compatible = "ge,achc" },
 679         { .compatible = "semtech,sx1301" },
 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         /* prevent new opens */
 791         mutex_lock(&device_list_lock);
 792         /* make sure ops on existing fds can abort cleanly */
 793         spin_lock_irq(&spidev->spi_lock);
 794         spidev->spi = NULL;
 795         spin_unlock_irq(&spidev->spi_lock);
 796
 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");