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