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         DECLARE_COMPLETION_ONSTACK(done);
 103         int status;
 104         struct spi_device *spi;
 105
 106         spin_lock_irq(&spidev->spi_lock);
 107         spi = spidev->spi;
 108         spin_unlock_irq(&spidev->spi_lock);
 109
 110         if (spi == NULL)
 111                 status = -ESHUTDOWN;
 112         else
 113                 status = spi_sync(spi, message);
 114
 115         if (status == 0)
 116                 status = message->actual_length;
 117
 118         return status;
 119 }
 120
 121 static inline ssize_t
 122 spidev_sync_write(struct spidev_data *spidev, size_t len)
 123 {
 124         struct spi_transfer     t = {
 125                         .tx_buf         = spidev->tx_buffer,
 126                         .len            = len,
 127                         .speed_hz       = spidev->speed_hz,
 128                 };
 129         struct spi_message      m;
 130
 131         spi_message_init(&m);
 132         spi_message_add_tail(&t, &m);
 133         return spidev_sync(spidev, &m);
 134 }
 135
 136 static inline ssize_t
 137 spidev_sync_read(struct spidev_data *spidev, size_t len)
 138 {
 139         struct spi_transfer     t = {
 140                         .rx_buf         = spidev->rx_buffer,
 141                         .len            = len,
 142                         .speed_hz       = spidev->speed_hz,
 143                 };
 144         struct spi_message      m;
 145
 146         spi_message_init(&m);
 147         spi_message_add_tail(&t, &m);
 148         return spidev_sync(spidev, &m);
 149 }
 150
 151 /*-------------------------------------------------------------------------*/
 152
 153 /* Read-only message with current device setup */
 154 static ssize_t
 155 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
 156 {
 157         struct spidev_data      *spidev;
 158         ssize_t                 status = 0;
 159
 160         /* chipselect only toggles at start or end of operation */
 161         if (count > bufsiz)
 162                 return -EMSGSIZE;
 163
 164         spidev = filp->private_data;
 165
 166         mutex_lock(&spidev->buf_lock);
 167         status = spidev_sync_read(spidev, count);
 168         if (status > 0) {
 169                 unsigned long   missing;
 170
 171                 missing = copy_to_user(buf, spidev->rx_buffer, status);
 172                 if (missing == status)
 173                         status = -EFAULT;
 174                 else
 175                         status = status - missing;
 176         }
 177         mutex_unlock(&spidev->buf_lock);
 178
 179         return status;
 180 }
 181
 182 /* Write-only message with current device setup */
 183 static ssize_t
 184 spidev_write(struct file *filp, const char __user *buf,
 185                 size_t count, loff_t *f_pos)
 186 {
 187         struct spidev_data      *spidev;
 188         ssize_t                 status = 0;
 189         unsigned long           missing;
 190
 191         /* chipselect only toggles at start or end of operation */
 192         if (count > bufsiz)
 193                 return -EMSGSIZE;
 194
 195         spidev = filp->private_data;
 196
 197         mutex_lock(&spidev->buf_lock);
 198         missing = copy_from_user(spidev->tx_buffer, buf, count);
 199         if (missing == 0)
 200                 status = spidev_sync_write(spidev, count);
 201         else
 202                 status = -EFAULT;
 203         mutex_unlock(&spidev->buf_lock);
 204
 205         return status;
 206 }
 207
 208 static int spidev_message(struct spidev_data *spidev,
 209                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
 210 {
 211         struct spi_message      msg;
 212         struct spi_transfer     *k_xfers;
 213         struct spi_transfer     *k_tmp;
 214         struct spi_ioc_transfer *u_tmp;
 215         unsigned                n, total, tx_total, rx_total;
 216         u8                      *tx_buf, *rx_buf;
 217         int                     status = -EFAULT;
 218
 219         spi_message_init(&msg);
 220         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
 221         if (k_xfers == NULL)
 222                 return -ENOMEM;
 223
 224         /* Construct spi_message, copying any tx data to bounce buffer.
 225          * We walk the array of user-provided transfers, using each one
 226          * to initialize a kernel version of the same transfer.
 227          */
 228         tx_buf = spidev->tx_buffer;
 229         rx_buf = spidev->rx_buffer;
 230         total = 0;
 231         tx_total = 0;
 232         rx_total = 0;
 233         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
 234                         n;
 235                         n--, k_tmp++, u_tmp++) {
 236                 k_tmp->len = u_tmp->len;
 237
 238                 total += k_tmp->len;
 239                 /* Since the function returns the total length of transfers
 240                  * on success, restrict the total to positive int values to
 241                  * avoid the return value looking like an error.  Also check
 242                  * each transfer length to avoid arithmetic overflow.
 243                  */
 244                 if (total > INT_MAX || k_tmp->len > INT_MAX) {
 245                         status = -EMSGSIZE;
 246                         goto done;
 247                 }
 248
 249                 if (u_tmp->rx_buf) {
 250                         /* this transfer needs space in RX bounce buffer */
 251                         rx_total += k_tmp->len;
 252                         if (rx_total > bufsiz) {
 253                                 status = -EMSGSIZE;
 254                                 goto done;
 255                         }
 256                         k_tmp->rx_buf = rx_buf;
 257                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
 258                                                 (uintptr_t) u_tmp->rx_buf,
 259                                                 u_tmp->len))
 260                                 goto done;
 261                         rx_buf += k_tmp->len;
 262                 }
 263                 if (u_tmp->tx_buf) {
 264                         /* this transfer needs space in TX bounce buffer */
 265                         tx_total += k_tmp->len;
 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 += k_tmp->len;
 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         rx_buf = spidev->rx_buffer;
 306         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
 307                 if (u_tmp->rx_buf) {
 308                         if (__copy_to_user((u8 __user *)
 309                                         (uintptr_t) u_tmp->rx_buf, rx_buf,
 310                                         u_tmp->len)) {
 311                                 status = -EFAULT;
 312                                 goto done;
 313                         }
 314                         rx_buf += u_tmp->len;
 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         struct spi_ioc_transfer *ioc;
 329         u32     tmp;
 330
 331         /* Check type, command number and direction */
 332         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
 333                         || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
 334                         || _IOC_DIR(cmd) != _IOC_WRITE)
 335                 return ERR_PTR(-ENOTTY);
 336
 337         tmp = _IOC_SIZE(cmd);
 338         if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
 339                 return ERR_PTR(-EINVAL);
 340         *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
 341         if (*n_ioc == 0)
 342                 return NULL;
 343
 344         /* copy into scratch area */
 345         ioc = kmalloc(tmp, GFP_KERNEL);
 346         if (!ioc)
 347                 return ERR_PTR(-ENOMEM);
 348         if (__copy_from_user(ioc, u_ioc, tmp)) {
 349                 kfree(ioc);
 350                 return ERR_PTR(-EFAULT);
 351         }
 352         return ioc;
 353 }
 354
 355 static long
 356 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 357 {
 358         int                     err = 0;
 359         int                     retval = 0;
 360         struct spidev_data      *spidev;
 361         struct spi_device       *spi;
 362         u32                     tmp;
 363         unsigned                n_ioc;
 364         struct spi_ioc_transfer *ioc;
 365
 366         /* Check type and command number */
 367         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
 368                 return -ENOTTY;
 369
 370         /* Check access direction once here; don't repeat below.
 371          * IOC_DIR is from the user perspective, while access_ok is
 372          * from the kernel perspective; so they look reversed.
 373          */
 374         if (_IOC_DIR(cmd) & _IOC_READ)
 375                 err = !access_ok(VERIFY_WRITE,
 376                                 (void __user *)arg, _IOC_SIZE(cmd));
 377         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
 378                 err = !access_ok(VERIFY_READ,
 379                                 (void __user *)arg, _IOC_SIZE(cmd));
 380         if (err)
 381                 return -EFAULT;
 382
 383         /* guard against device removal before, or while,
 384          * we issue this ioctl.
 385          */
 386         spidev = filp->private_data;
 387         spin_lock_irq(&spidev->spi_lock);
 388         spi = spi_dev_get(spidev->spi);
 389         spin_unlock_irq(&spidev->spi_lock);
 390
 391         if (spi == NULL)
 392                 return -ESHUTDOWN;
 393
 394         /* use the buffer lock here for triple duty:
 395          *  - prevent I/O (from us) so calling spi_setup() is safe;
 396          *  - prevent concurrent SPI_IOC_WR_* from morphing
 397          *    data fields while SPI_IOC_RD_* reads them;
 398          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
 399          */
 400         mutex_lock(&spidev->buf_lock);
 401
 402         switch (cmd) {
 403         /* read requests */
 404         case SPI_IOC_RD_MODE:
 405                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 406                                         (__u8 __user *)arg);
 407                 break;
 408         case SPI_IOC_RD_MODE32:
 409                 retval = __put_user(spi->mode & SPI_MODE_MASK,
 410                                         (__u32 __user *)arg);
 411                 break;
 412         case SPI_IOC_RD_LSB_FIRST:
 413                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
 414                                         (__u8 __user *)arg);
 415                 break;
 416         case SPI_IOC_RD_BITS_PER_WORD:
 417                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
 418                 break;
 419         case SPI_IOC_RD_MAX_SPEED_HZ:
 420                 retval = __put_user(spidev->speed_hz, (__u32 __user *)arg);
 421                 break;
 422
 423         /* write requests */
 424         case SPI_IOC_WR_MODE:
 425         case SPI_IOC_WR_MODE32:
 426                 if (cmd == SPI_IOC_WR_MODE)
 427                         retval = __get_user(tmp, (u8 __user *)arg);
 428                 else
 429                         retval = __get_user(tmp, (u32 __user *)arg);
 430                 if (retval == 0) {
 431                         u32     save = spi->mode;
 432
 433                         if (tmp & ~SPI_MODE_MASK) {
 434                                 retval = -EINVAL;
 435                                 break;
 436                         }
 437
 438                         tmp |= spi->mode & ~SPI_MODE_MASK;
 439                         spi->mode = (u16)tmp;
 440                         retval = spi_setup(spi);
 441                         if (retval < 0)
 442                                 spi->mode = save;
 443                         else
 444                                 dev_dbg(&spi->dev, "spi mode %x\n", tmp);
 445                 }
 446                 break;
 447         case SPI_IOC_WR_LSB_FIRST:
 448                 retval = __get_user(tmp, (__u8 __user *)arg);
 449                 if (retval == 0) {
 450                         u32     save = spi->mode;
 451
 452                         if (tmp)
 453                                 spi->mode |= SPI_LSB_FIRST;
 454                         else
 455                                 spi->mode &= ~SPI_LSB_FIRST;
 456                         retval = spi_setup(spi);
 457                         if (retval < 0)
 458                                 spi->mode = save;
 459                         else
 460                                 dev_dbg(&spi->dev, "%csb first\n",
 461                                                 tmp ? 'l' : 'm');
 462                 }
 463                 break;
 464         case SPI_IOC_WR_BITS_PER_WORD:
 465                 retval = __get_user(tmp, (__u8 __user *)arg);
 466                 if (retval == 0) {
 467                         u8      save = spi->bits_per_word;
 468
 469                         spi->bits_per_word = tmp;
 470                         retval = spi_setup(spi);
 471                         if (retval < 0)
 472                                 spi->bits_per_word = save;
 473                         else
 474                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
 475                 }
 476                 break;
 477         case SPI_IOC_WR_MAX_SPEED_HZ:
 478                 retval = __get_user(tmp, (__u32 __user *)arg);
 479                 if (retval == 0) {
 480                         u32     save = spi->max_speed_hz;
 481
 482                         spi->max_speed_hz = tmp;
 483                         retval = spi_setup(spi);
 484                         if (retval >= 0)
 485                                 spidev->speed_hz = tmp;
 486                         else
 487                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
 488                         spi->max_speed_hz = save;
 489                 }
 490                 break;
 491
 492         default:
 493                 /* segmented and/or full-duplex I/O request */
 494                 /* Check message and copy into scratch area */
 495                 ioc = spidev_get_ioc_message(cmd,
 496                                 (struct spi_ioc_transfer __user *)arg, &n_ioc);
 497                 if (IS_ERR(ioc)) {
 498                         retval = PTR_ERR(ioc);
 499                         break;
 500                 }
 501                 if (!ioc)
 502                         break;  /* n_ioc is also 0 */
 503
 504                 /* translate to spi_message, execute */
 505                 retval = spidev_message(spidev, ioc, n_ioc);
 506                 kfree(ioc);
 507                 break;
 508         }
 509
 510         mutex_unlock(&spidev->buf_lock);
 511         spi_dev_put(spi);
 512         return retval;
 513 }
 514
 515 #ifdef CONFIG_COMPAT
 516 static long
 517 spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
 518                 unsigned long arg)
 519 {
 520         struct spi_ioc_transfer __user  *u_ioc;
 521         int                             retval = 0;
 522         struct spidev_data              *spidev;
 523         struct spi_device               *spi;
 524         unsigned                        n_ioc, n;
 525         struct spi_ioc_transfer         *ioc;
 526
 527         u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
 528         if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
 529                 return -EFAULT;
 530
 531         /* guard against device removal before, or while,
 532          * we issue this ioctl.
 533          */
 534         spidev = filp->private_data;
 535         spin_lock_irq(&spidev->spi_lock);
 536         spi = spi_dev_get(spidev->spi);
 537         spin_unlock_irq(&spidev->spi_lock);
 538
 539         if (spi == NULL)
 540                 return -ESHUTDOWN;
 541
 542         /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
 543         mutex_lock(&spidev->buf_lock);
 544
 545         /* Check message and copy into scratch area */
 546         ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
 547         if (IS_ERR(ioc)) {
 548                 retval = PTR_ERR(ioc);
 549                 goto done;
 550         }
 551         if (!ioc)
 552                 goto done;      /* n_ioc is also 0 */
 553
 554         /* Convert buffer pointers */
 555         for (n = 0; n < n_ioc; n++) {
 556                 ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
 557                 ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
 558         }
 559
 560         /* translate to spi_message, execute */
 561         retval = spidev_message(spidev, ioc, n_ioc);
 562         kfree(ioc);
 563
 564 done:
 565         mutex_unlock(&spidev->buf_lock);
 566         spi_dev_put(spi);
 567         return retval;
 568 }
 569
 570 static long
 571 spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 572 {
 573         if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
 574                         && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
 575                         && _IOC_DIR(cmd) == _IOC_WRITE)
 576                 return spidev_compat_ioc_message(filp, cmd, arg);
 577
 578         return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 579 }
 580 #else
 581 #define spidev_compat_ioctl NULL
 582 #endif /* CONFIG_COMPAT */
 583
 584 static int spidev_open(struct inode *inode, struct file *filp)
 585 {
 586         struct spidev_data      *spidev;
 587         int                     status = -ENXIO;
 588
 589         mutex_lock(&device_list_lock);
 590
 591         list_for_each_entry(spidev, &device_list, device_entry) {
 592                 if (spidev->devt == inode->i_rdev) {
 593                         status = 0;
 594                         break;
 595                 }
 596         }
 597
 598         if (status) {
 599                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
 600                 goto err_find_dev;
 601         }
 602
 603         if (!spidev->tx_buffer) {
 604                 spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 605                 if (!spidev->tx_buffer) {
 606                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 607                         status = -ENOMEM;
 608                         goto err_find_dev;
 609                 }
 610         }
 611
 612         if (!spidev->rx_buffer) {
 613                 spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);
 614                 if (!spidev->rx_buffer) {
 615                         dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
 616                         status = -ENOMEM;
 617                         goto err_alloc_rx_buf;
 618                 }
 619         }
 620
 621         spidev->users++;
 622         filp->private_data = spidev;
 623         nonseekable_open(inode, filp);
 624
 625         mutex_unlock(&device_list_lock);
 626         return 0;
 627
 628 err_alloc_rx_buf:
 629         kfree(spidev->tx_buffer);
 630         spidev->tx_buffer = NULL;
 631 err_find_dev:
 632         mutex_unlock(&device_list_lock);
 633         return status;
 634 }
 635
 636 static int spidev_release(struct inode *inode, struct file *filp)
 637 {
 638         struct spidev_data      *spidev;
 639
 640         mutex_lock(&device_list_lock);
 641         spidev = filp->private_data;
 642         filp->private_data = NULL;
 643
 644         /* last close? */
 645         spidev->users--;
 646         if (!spidev->users) {
 647                 int             dofree;
 648
 649                 kfree(spidev->tx_buffer);
 650                 spidev->tx_buffer = NULL;
 651
 652                 kfree(spidev->rx_buffer);
 653                 spidev->rx_buffer = NULL;
 654
 655                 spin_lock_irq(&spidev->spi_lock);
 656                 if (spidev->spi)
 657                         spidev->speed_hz = spidev->spi->max_speed_hz;
 658
 659                 /* ... after we unbound from the underlying device? */
 660                 dofree = (spidev->spi == NULL);
 661                 spin_unlock_irq(&spidev->spi_lock);
 662
 663                 if (dofree)
 664                         kfree(spidev);
 665         }
 666         mutex_unlock(&device_list_lock);
 667
 668         return 0;
 669 }
 670
 671 static const struct file_operations spidev_fops = {
 672         .owner =        THIS_MODULE,
 673         /* REVISIT switch to aio primitives, so that userspace
 674          * gets more complete API coverage.  It'll simplify things
 675          * too, except for the locking.
 676          */
 677         .write =        spidev_write,
 678         .read =         spidev_read,
 679         .unlocked_ioctl = spidev_ioctl,
 680         .compat_ioctl = spidev_compat_ioctl,
 681         .open =         spidev_open,
 682         .release =      spidev_release,
 683         .llseek =       no_llseek,
 684 };
 685
 686 /*-------------------------------------------------------------------------*/
 687
 688 /* The main reason to have this class is to make mdev/udev create the
 689  * /dev/spidevB.C character device nodes exposing our userspace API.
 690  * It also simplifies memory management.
 691  */
 692
 693 static struct class *spidev_class;
 694
 695 #ifdef CONFIG_OF
 696 static const struct of_device_id spidev_dt_ids[] = {
 697         { .compatible = "rohm,dh2228fv" },
 698         { .compatible = "lineartechnology,ltc2488" },
 699         {},
 700 };
 701 MODULE_DEVICE_TABLE(of, spidev_dt_ids);
 702 #endif
 703
 704 #ifdef CONFIG_ACPI
 705
 706 /* Dummy SPI devices not to be used in production systems */
 707 #define SPIDEV_ACPI_DUMMY       1
 708
 709 static const struct acpi_device_id spidev_acpi_ids[] = {
 710         /*
 711          * The ACPI SPT000* devices are only meant for development and
 712          * testing. Systems used in production should have a proper ACPI
 713          * description of the connected peripheral and they should also use
 714          * a proper driver instead of poking directly to the SPI bus.
 715          */
 716         { "SPT0001", SPIDEV_ACPI_DUMMY },
 717         { "SPT0002", SPIDEV_ACPI_DUMMY },
 718         { "SPT0003", SPIDEV_ACPI_DUMMY },
 719         {},
 720 };
 721 MODULE_DEVICE_TABLE(acpi, spidev_acpi_ids);
 722
 723 static void spidev_probe_acpi(struct spi_device *spi)
 724 {
 725         const struct acpi_device_id *id;
 726
 727         if (!has_acpi_companion(&spi->dev))
 728                 return;
 729
 730         id = acpi_match_device(spidev_acpi_ids, &spi->dev);
 731         if (WARN_ON(!id))
 732                 return;
 733
 734         if (id->driver_data == SPIDEV_ACPI_DUMMY)
 735                 dev_warn(&spi->dev, "do not use this driver in production systems!\n");
 736 }
 737 #else
 738 static inline void spidev_probe_acpi(struct spi_device *spi) {}
 739 #endif
 740
 741 /*-------------------------------------------------------------------------*/
 742
 743 static int spidev_probe(struct spi_device *spi)
 744 {
 745         struct spidev_data      *spidev;
 746         int                     status;
 747         unsigned long           minor;
 748
 749         /*
 750          * spidev should never be referenced in DT without a specific
 751          * compatible string, it is a Linux implementation thing
 752          * rather than a description of the hardware.
 753          */
 754         if (spi->dev.of_node && !of_match_device(spidev_dt_ids, &spi->dev)) {
 755                 dev_err(&spi->dev, "buggy DT: spidev listed directly in DT\n");
 756                 WARN_ON(spi->dev.of_node &&
 757                         !of_match_device(spidev_dt_ids, &spi->dev));
 758         }
 759
 760         spidev_probe_acpi(spi);
 761
 762         /* Allocate driver data */
 763         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
 764         if (!spidev)
 765                 return -ENOMEM;
 766
 767         /* Initialize the driver data */
 768         spidev->spi = spi;
 769         spin_lock_init(&spidev->spi_lock);
 770         mutex_init(&spidev->buf_lock);
 771
 772         INIT_LIST_HEAD(&spidev->device_entry);
 773
 774         /* If we can allocate a minor number, hook up this device.
 775          * Reusing minors is fine so long as udev or mdev is working.
 776          */
 777         mutex_lock(&device_list_lock);
 778         minor = find_first_zero_bit(minors, N_SPI_MINORS);
 779         if (minor < N_SPI_MINORS) {
 780                 struct device *dev;
 781
 782                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
 783                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
 784                                     spidev, "spidev%d.%d",
 785                                     spi->master->bus_num, spi->chip_select);
 786                 status = PTR_ERR_OR_ZERO(dev);
 787         } else {
 788                 dev_dbg(&spi->dev, "no minor number available!\n");
 789                 status = -ENODEV;
 790         }
 791         if (status == 0) {
 792                 set_bit(minor, minors);
 793                 list_add(&spidev->device_entry, &device_list);
 794         }
 795         mutex_unlock(&device_list_lock);
 796
 797         spidev->speed_hz = spi->max_speed_hz;
 798
 799         if (status == 0)
 800                 spi_set_drvdata(spi, spidev);
 801         else
 802                 kfree(spidev);
 803
 804         return status;
 805 }
 806
 807 static int spidev_remove(struct spi_device *spi)
 808 {
 809         struct spidev_data      *spidev = spi_get_drvdata(spi);
 810
 811         /* make sure ops on existing fds can abort cleanly */
 812         spin_lock_irq(&spidev->spi_lock);
 813         spidev->spi = NULL;
 814         spin_unlock_irq(&spidev->spi_lock);
 815
 816         /* prevent new opens */
 817         mutex_lock(&device_list_lock);
 818         list_del(&spidev->device_entry);
 819         device_destroy(spidev_class, spidev->devt);
 820         clear_bit(MINOR(spidev->devt), minors);
 821         if (spidev->users == 0)
 822                 kfree(spidev);
 823         mutex_unlock(&device_list_lock);
 824
 825         return 0;
 826 }
 827
 828 static struct spi_driver spidev_spi_driver = {
 829         .driver = {
 830                 .name =         "spidev",
 831                 .of_match_table = of_match_ptr(spidev_dt_ids),
 832                 .acpi_match_table = ACPI_PTR(spidev_acpi_ids),
 833         },
 834         .probe =        spidev_probe,
 835         .remove =       spidev_remove,
 836
 837         /* NOTE:  suspend/resume methods are not necessary here.
 838          * We don't do anything except pass the requests to/from
 839          * the underlying controller.  The refrigerator handles
 840          * most issues; the controller driver handles the rest.
 841          */
 842 };
 843
 844 /*-------------------------------------------------------------------------*/
 845
 846 static int __init spidev_init(void)
 847 {
 848         int status;
 849
 850         /* Claim our 256 reserved device numbers.  Then register a class
 851          * that will key udev/mdev to add/remove /dev nodes.  Last, register
 852          * the driver which manages those device numbers.
 853          */
 854         BUILD_BUG_ON(N_SPI_MINORS > 256);
 855         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
 856         if (status < 0)
 857                 return status;
 858
 859         spidev_class = class_create(THIS_MODULE, "spidev");
 860         if (IS_ERR(spidev_class)) {
 861                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 862                 return PTR_ERR(spidev_class);
 863         }
 864
 865         status = spi_register_driver(&spidev_spi_driver);
 866         if (status < 0) {
 867                 class_destroy(spidev_class);
 868                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 869         }
 870         return status;
 871 }
 872 module_init(spidev_init);
 873
 874 static void __exit spidev_exit(void)
 875 {
 876         spi_unregister_driver(&spidev_spi_driver);
 877         class_destroy(spidev_class);
 878         unregister_chrdev(SPIDEV_MAJOR, spidev_spi_driver.driver.name);
 879 }
 880 module_exit(spidev_exit);
 881
 882 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
 883 MODULE_DESCRIPTION("User mode SPI device interface");
 884 MODULE_LICENSE("GPL");
 885 MODULE_ALIAS("spi:spidev");