drivers/iio/industrialio-buffer.c

   1 /* The industrial I/O core
   2  *
   3  * Copyright (c) 2008 Jonathan Cameron
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * Handling of buffer allocation / resizing.
  10  *
  11  *
  12  * Things to look at here.
  13  * - Better memory allocation techniques?
  14  * - Alternative access techniques?
  15  */
  16 #include <linux/kernel.h>
  17 #include <linux/export.h>
  18 #include <linux/device.h>
  19 #include <linux/fs.h>
  20 #include <linux/cdev.h>
  21 #include <linux/slab.h>
  22 #include <linux/poll.h>
  23 #include <linux/sched.h>
  24
  25 #include <linux/iio/iio.h>
  26 #include "iio_core.h"
  27 #include <linux/iio/sysfs.h>
  28 #include <linux/iio/buffer.h>
  29
  30 static const char * const iio_endian_prefix[] = {
  31         [IIO_BE] = "be",
  32         [IIO_LE] = "le",
  33 };
  34
  35 static bool iio_buffer_is_active(struct iio_buffer *buf)
  36 {
  37         return !list_empty(&buf->buffer_list);
  38 }
  39
  40 static size_t iio_buffer_data_available(struct iio_buffer *buf)
  41 {
  42         return buf->access->data_available(buf);
  43 }
  44
  45 static int iio_buffer_flush_hwfifo(struct iio_dev *indio_dev,
  46                                    struct iio_buffer *buf, size_t required)
  47 {
  48         if (!indio_dev->info->hwfifo_flush_to_buffer)
  49                 return -ENODEV;
  50
  51         return indio_dev->info->hwfifo_flush_to_buffer(indio_dev, required);
  52 }
  53
  54 static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
  55                              size_t to_wait, int to_flush)
  56 {
  57         size_t avail;
  58         int flushed = 0;
  59
  60         /* wakeup if the device was unregistered */
  61         if (!indio_dev->info)
  62                 return true;
  63
  64         /* drain the buffer if it was disabled */
  65         if (!iio_buffer_is_active(buf)) {
  66                 to_wait = min_t(size_t, to_wait, 1);
  67                 to_flush = 0;
  68         }
  69
  70         avail = iio_buffer_data_available(buf);
  71
  72         if (avail >= to_wait) {
  73                 /* force a flush for non-blocking reads */
  74                 if (!to_wait && !avail && to_flush)
  75                         iio_buffer_flush_hwfifo(indio_dev, buf, to_flush);
  76                 return true;
  77         }
  78
  79         if (to_flush)
  80                 flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
  81                                                   to_wait - avail);
  82         if (flushed <= 0)
  83                 return false;
  84
  85         if (avail + flushed >= to_wait)
  86                 return true;
  87
  88         return false;
  89 }
  90
  91 /**
  92  * iio_buffer_read_first_n_outer() - chrdev read for buffer access
  93  *
  94  * This function relies on all buffer implementations having an
  95  * iio_buffer as their first element.
  96  **/
  97 ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
  98                                       size_t n, loff_t *f_ps)
  99 {
 100         struct iio_dev *indio_dev = filp->private_data;
 101         struct iio_buffer *rb = indio_dev->buffer;
 102         size_t datum_size;
 103         size_t to_wait = 0;
 104         size_t to_read;
 105         int ret;
 106
 107         if (!indio_dev->info)
 108                 return -ENODEV;
 109
 110         if (!rb || !rb->access->read_first_n)
 111                 return -EINVAL;
 112
 113         datum_size = rb->bytes_per_datum;
 114
 115         /*
 116          * If datum_size is 0 there will never be anything to read from the
 117          * buffer, so signal end of file now.
 118          */
 119         if (!datum_size)
 120                 return 0;
 121
 122         to_read = min_t(size_t, n / datum_size, rb->watermark);
 123
 124         if (!(filp->f_flags & O_NONBLOCK))
 125                 to_wait = to_read;
 126
 127         do {
 128                 ret = wait_event_interruptible(rb->pollq,
 129                         iio_buffer_ready(indio_dev, rb, to_wait, to_read));
 130                 if (ret)
 131                         return ret;
 132
 133                 if (!indio_dev->info)
 134                         return -ENODEV;
 135
 136                 ret = rb->access->read_first_n(rb, n, buf);
 137                 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
 138                         ret = -EAGAIN;
 139          } while (ret == 0);
 140
 141         return ret;
 142 }
 143
 144 /**
 145  * iio_buffer_poll() - poll the buffer to find out if it has data
 146  */
 147 unsigned int iio_buffer_poll(struct file *filp,
 148                              struct poll_table_struct *wait)
 149 {
 150         struct iio_dev *indio_dev = filp->private_data;
 151         struct iio_buffer *rb = indio_dev->buffer;
 152
 153         if (!indio_dev->info)
 154                 return -ENODEV;
 155
 156         poll_wait(filp, &rb->pollq, wait);
 157         if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0))
 158                 return POLLIN | POLLRDNORM;
 159         return 0;
 160 }
 161
 162 /**
 163  * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
 164  * @indio_dev: The IIO device
 165  *
 166  * Wakes up the event waitqueue used for poll(). Should usually
 167  * be called when the device is unregistered.
 168  */
 169 void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
 170 {
 171         if (!indio_dev->buffer)
 172                 return;
 173
 174         wake_up(&indio_dev->buffer->pollq);
 175 }
 176
 177 void iio_buffer_init(struct iio_buffer *buffer)
 178 {
 179         INIT_LIST_HEAD(&buffer->demux_list);
 180         INIT_LIST_HEAD(&buffer->buffer_list);
 181         init_waitqueue_head(&buffer->pollq);
 182         kref_init(&buffer->ref);
 183         buffer->watermark = 1;
 184 }
 185 EXPORT_SYMBOL(iio_buffer_init);
 186
 187 static ssize_t iio_show_scan_index(struct device *dev,
 188                                    struct device_attribute *attr,
 189                                    char *buf)
 190 {
 191         return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
 192 }
 193
 194 static ssize_t iio_show_fixed_type(struct device *dev,
 195                                    struct device_attribute *attr,
 196                                    char *buf)
 197 {
 198         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 199         u8 type = this_attr->c->scan_type.endianness;
 200
 201         if (type == IIO_CPU) {
 202 #ifdef __LITTLE_ENDIAN
 203                 type = IIO_LE;
 204 #else
 205                 type = IIO_BE;
 206 #endif
 207         }
 208         if (this_attr->c->scan_type.repeat > 1)
 209                 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
 210                        iio_endian_prefix[type],
 211                        this_attr->c->scan_type.sign,
 212                        this_attr->c->scan_type.realbits,
 213                        this_attr->c->scan_type.storagebits,
 214                        this_attr->c->scan_type.repeat,
 215                        this_attr->c->scan_type.shift);
 216                 else
 217                         return sprintf(buf, "%s:%c%d/%d>>%u\n",
 218                        iio_endian_prefix[type],
 219                        this_attr->c->scan_type.sign,
 220                        this_attr->c->scan_type.realbits,
 221                        this_attr->c->scan_type.storagebits,
 222                        this_attr->c->scan_type.shift);
 223 }
 224
 225 static ssize_t iio_scan_el_show(struct device *dev,
 226                                 struct device_attribute *attr,
 227                                 char *buf)
 228 {
 229         int ret;
 230         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 231
 232         /* Ensure ret is 0 or 1. */
 233         ret = !!test_bit(to_iio_dev_attr(attr)->address,
 234                        indio_dev->buffer->scan_mask);
 235
 236         return sprintf(buf, "%d\n", ret);
 237 }
 238
 239 /* Note NULL used as error indicator as it doesn't make sense. */
 240 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
 241                                           unsigned int masklength,
 242                                           const unsigned long *mask,
 243                                           bool strict)
 244 {
 245         if (bitmap_empty(mask, masklength))
 246                 return NULL;
 247         while (*av_masks) {
 248                 if (strict) {
 249                         if (bitmap_equal(mask, av_masks, masklength))
 250                                 return av_masks;
 251                 } else {
 252                         if (bitmap_subset(mask, av_masks, masklength))
 253                                 return av_masks;
 254                 }
 255                 av_masks += BITS_TO_LONGS(masklength);
 256         }
 257         return NULL;
 258 }
 259
 260 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
 261         const unsigned long *mask)
 262 {
 263         if (!indio_dev->setup_ops->validate_scan_mask)
 264                 return true;
 265
 266         return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
 267 }
 268
 269 /**
 270  * iio_scan_mask_set() - set particular bit in the scan mask
 271  * @indio_dev: the iio device
 272  * @buffer: the buffer whose scan mask we are interested in
 273  * @bit: the bit to be set.
 274  *
 275  * Note that at this point we have no way of knowing what other
 276  * buffers might request, hence this code only verifies that the
 277  * individual buffers request is plausible.
 278  */
 279 static int iio_scan_mask_set(struct iio_dev *indio_dev,
 280                       struct iio_buffer *buffer, int bit)
 281 {
 282         const unsigned long *mask;
 283         unsigned long *trialmask;
 284
 285         trialmask = kmalloc(sizeof(*trialmask)*
 286                             BITS_TO_LONGS(indio_dev->masklength),
 287                             GFP_KERNEL);
 288
 289         if (trialmask == NULL)
 290                 return -ENOMEM;
 291         if (!indio_dev->masklength) {
 292                 WARN_ON("Trying to set scanmask prior to registering buffer\n");
 293                 goto err_invalid_mask;
 294         }
 295         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 296         set_bit(bit, trialmask);
 297
 298         if (!iio_validate_scan_mask(indio_dev, trialmask))
 299                 goto err_invalid_mask;
 300
 301         if (indio_dev->available_scan_masks) {
 302                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 303                                            indio_dev->masklength,
 304                                            trialmask, false);
 305                 if (!mask)
 306                         goto err_invalid_mask;
 307         }
 308         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 309
 310         kfree(trialmask);
 311
 312         return 0;
 313
 314 err_invalid_mask:
 315         kfree(trialmask);
 316         return -EINVAL;
 317 }
 318
 319 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 320 {
 321         clear_bit(bit, buffer->scan_mask);
 322         return 0;
 323 }
 324
 325 static ssize_t iio_scan_el_store(struct device *dev,
 326                                  struct device_attribute *attr,
 327                                  const char *buf,
 328                                  size_t len)
 329 {
 330         int ret;
 331         bool state;
 332         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 333         struct iio_buffer *buffer = indio_dev->buffer;
 334         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 335
 336         ret = strtobool(buf, &state);
 337         if (ret < 0)
 338                 return ret;
 339         mutex_lock(&indio_dev->mlock);
 340         if (iio_buffer_is_active(indio_dev->buffer)) {
 341                 ret = -EBUSY;
 342                 goto error_ret;
 343         }
 344         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 345         if (ret < 0)
 346                 goto error_ret;
 347         if (!state && ret) {
 348                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 349                 if (ret)
 350                         goto error_ret;
 351         } else if (state && !ret) {
 352                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 353                 if (ret)
 354                         goto error_ret;
 355         }
 356
 357 error_ret:
 358         mutex_unlock(&indio_dev->mlock);
 359
 360         return ret < 0 ? ret : len;
 361
 362 }
 363
 364 static ssize_t iio_scan_el_ts_show(struct device *dev,
 365                                    struct device_attribute *attr,
 366                                    char *buf)
 367 {
 368         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 369         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 370 }
 371
 372 static ssize_t iio_scan_el_ts_store(struct device *dev,
 373                                     struct device_attribute *attr,
 374                                     const char *buf,
 375                                     size_t len)
 376 {
 377         int ret;
 378         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 379         bool state;
 380
 381         ret = strtobool(buf, &state);
 382         if (ret < 0)
 383                 return ret;
 384
 385         mutex_lock(&indio_dev->mlock);
 386         if (iio_buffer_is_active(indio_dev->buffer)) {
 387                 ret = -EBUSY;
 388                 goto error_ret;
 389         }
 390         indio_dev->buffer->scan_timestamp = state;
 391 error_ret:
 392         mutex_unlock(&indio_dev->mlock);
 393
 394         return ret ? ret : len;
 395 }
 396
 397 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 398                                         const struct iio_chan_spec *chan)
 399 {
 400         int ret, attrcount = 0;
 401         struct iio_buffer *buffer = indio_dev->buffer;
 402
 403         ret = __iio_add_chan_devattr("index",
 404                                      chan,
 405                                      &iio_show_scan_index,
 406                                      NULL,
 407                                      0,
 408                                      IIO_SEPARATE,
 409                                      &indio_dev->dev,
 410                                      &buffer->scan_el_dev_attr_list);
 411         if (ret)
 412                 return ret;
 413         attrcount++;
 414         ret = __iio_add_chan_devattr("type",
 415                                      chan,
 416                                      &iio_show_fixed_type,
 417                                      NULL,
 418                                      0,
 419                                      0,
 420                                      &indio_dev->dev,
 421                                      &buffer->scan_el_dev_attr_list);
 422         if (ret)
 423                 return ret;
 424         attrcount++;
 425         if (chan->type != IIO_TIMESTAMP)
 426                 ret = __iio_add_chan_devattr("en",
 427                                              chan,
 428                                              &iio_scan_el_show,
 429                                              &iio_scan_el_store,
 430                                              chan->scan_index,
 431                                              0,
 432                                              &indio_dev->dev,
 433                                              &buffer->scan_el_dev_attr_list);
 434         else
 435                 ret = __iio_add_chan_devattr("en",
 436                                              chan,
 437                                              &iio_scan_el_ts_show,
 438                                              &iio_scan_el_ts_store,
 439                                              chan->scan_index,
 440                                              0,
 441                                              &indio_dev->dev,
 442                                              &buffer->scan_el_dev_attr_list);
 443         if (ret)
 444                 return ret;
 445         attrcount++;
 446         ret = attrcount;
 447         return ret;
 448 }
 449
 450 static ssize_t iio_buffer_read_length(struct device *dev,
 451                                       struct device_attribute *attr,
 452                                       char *buf)
 453 {
 454         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 455         struct iio_buffer *buffer = indio_dev->buffer;
 456
 457         return sprintf(buf, "%d\n", buffer->length);
 458 }
 459
 460 static ssize_t iio_buffer_write_length(struct device *dev,
 461                                        struct device_attribute *attr,
 462                                        const char *buf, size_t len)
 463 {
 464         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 465         struct iio_buffer *buffer = indio_dev->buffer;
 466         unsigned int val;
 467         int ret;
 468
 469         ret = kstrtouint(buf, 10, &val);
 470         if (ret)
 471                 return ret;
 472
 473         if (val == buffer->length)
 474                 return len;
 475
 476         mutex_lock(&indio_dev->mlock);
 477         if (iio_buffer_is_active(indio_dev->buffer)) {
 478                 ret = -EBUSY;
 479         } else {
 480                 buffer->access->set_length(buffer, val);
 481                 ret = 0;
 482         }
 483         if (ret)
 484                 goto out;
 485         if (buffer->length && buffer->length < buffer->watermark)
 486                 buffer->watermark = buffer->length;
 487 out:
 488         mutex_unlock(&indio_dev->mlock);
 489
 490         return ret ? ret : len;
 491 }
 492
 493 static ssize_t iio_buffer_show_enable(struct device *dev,
 494                                       struct device_attribute *attr,
 495                                       char *buf)
 496 {
 497         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 498         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 499 }
 500
 501 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 502                                 const unsigned long *mask, bool timestamp)
 503 {
 504         const struct iio_chan_spec *ch;
 505         unsigned bytes = 0;
 506         int length, i;
 507
 508         /* How much space will the demuxed element take? */
 509         for_each_set_bit(i, mask,
 510                          indio_dev->masklength) {
 511                 ch = iio_find_channel_from_si(indio_dev, i);
 512                 if (ch->scan_type.repeat > 1)
 513                         length = ch->scan_type.storagebits / 8 *
 514                                 ch->scan_type.repeat;
 515                 else
 516                         length = ch->scan_type.storagebits / 8;
 517                 bytes = ALIGN(bytes, length);
 518                 bytes += length;
 519         }
 520         if (timestamp) {
 521                 ch = iio_find_channel_from_si(indio_dev,
 522                                               indio_dev->scan_index_timestamp);
 523                 if (ch->scan_type.repeat > 1)
 524                         length = ch->scan_type.storagebits / 8 *
 525                                 ch->scan_type.repeat;
 526                 else
 527                         length = ch->scan_type.storagebits / 8;
 528                 bytes = ALIGN(bytes, length);
 529                 bytes += length;
 530         }
 531         return bytes;
 532 }
 533
 534 static void iio_buffer_activate(struct iio_dev *indio_dev,
 535         struct iio_buffer *buffer)
 536 {
 537         iio_buffer_get(buffer);
 538         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 539 }
 540
 541 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 542 {
 543         list_del_init(&buffer->buffer_list);
 544         wake_up_interruptible(&buffer->pollq);
 545         iio_buffer_put(buffer);
 546 }
 547
 548 static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
 549 {
 550         struct iio_buffer *buffer, *_buffer;
 551
 552         list_for_each_entry_safe(buffer, _buffer,
 553                         &indio_dev->buffer_list, buffer_list)
 554                 iio_buffer_deactivate(buffer);
 555 }
 556
 557 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 558         struct iio_buffer *buffer)
 559 {
 560         unsigned int bytes;
 561
 562         if (!buffer->access->set_bytes_per_datum)
 563                 return;
 564
 565         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 566                 buffer->scan_timestamp);
 567
 568         buffer->access->set_bytes_per_datum(buffer, bytes);
 569 }
 570
 571 static int iio_buffer_request_update(struct iio_dev *indio_dev,
 572         struct iio_buffer *buffer)
 573 {
 574         int ret;
 575
 576         iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 577         if (buffer->access->request_update) {
 578                 ret = buffer->access->request_update(buffer);
 579                 if (ret) {
 580                         dev_dbg(&indio_dev->dev,
 581                                "Buffer not started: buffer parameter update failed (%d)\n",
 582                                 ret);
 583                         return ret;
 584                 }
 585         }
 586
 587         return 0;
 588 }
 589
 590 static void iio_free_scan_mask(struct iio_dev *indio_dev,
 591         const unsigned long *mask)
 592 {
 593         /* If the mask is dynamically allocated free it, otherwise do nothing */
 594         if (!indio_dev->available_scan_masks)
 595                 kfree(mask);
 596 }
 597
 598 struct iio_device_config {
 599         unsigned int mode;
 600         const unsigned long *scan_mask;
 601         unsigned int scan_bytes;
 602         bool scan_timestamp;
 603 };
 604
 605 static int iio_verify_update(struct iio_dev *indio_dev,
 606         struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
 607         struct iio_device_config *config)
 608 {
 609         unsigned long *compound_mask;
 610         const unsigned long *scan_mask;
 611         bool strict_scanmask = false;
 612         struct iio_buffer *buffer;
 613         bool scan_timestamp;
 614         unsigned int modes;
 615
 616         memset(config, 0, sizeof(*config));
 617
 618         /*
 619          * If there is just one buffer and we are removing it there is nothing
 620          * to verify.
 621          */
 622         if (remove_buffer && !insert_buffer &&
 623                 list_is_singular(&indio_dev->buffer_list))
 624                         return 0;
 625
 626         modes = indio_dev->modes;
 627
 628         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 629                 if (buffer == remove_buffer)
 630                         continue;
 631                 modes &= buffer->access->modes;
 632         }
 633
 634         if (insert_buffer)
 635                 modes &= insert_buffer->access->modes;
 636
 637         /* Definitely possible for devices to support both of these. */
 638         if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
 639                 config->mode = INDIO_BUFFER_TRIGGERED;
 640         } else if (modes & INDIO_BUFFER_HARDWARE) {
 641                 /*
 642                  * Keep things simple for now and only allow a single buffer to
 643                  * be connected in hardware mode.
 644                  */
 645                 if (insert_buffer && !list_empty(&indio_dev->buffer_list))
 646                         return -EINVAL;
 647                 config->mode = INDIO_BUFFER_HARDWARE;
 648                 strict_scanmask = true;
 649         } else if (modes & INDIO_BUFFER_SOFTWARE) {
 650                 config->mode = INDIO_BUFFER_SOFTWARE;
 651         } else {
 652                 /* Can only occur on first buffer */
 653                 if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
 654                         dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
 655                 return -EINVAL;
 656         }
 657
 658         /* What scan mask do we actually have? */
 659         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 660                                 sizeof(long), GFP_KERNEL);
 661         if (compound_mask == NULL)
 662                 return -ENOMEM;
 663
 664         scan_timestamp = false;
 665
 666         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 667                 if (buffer == remove_buffer)
 668                         continue;
 669                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 670                           indio_dev->masklength);
 671                 scan_timestamp |= buffer->scan_timestamp;
 672         }
 673
 674         if (insert_buffer) {
 675                 bitmap_or(compound_mask, compound_mask,
 676                           insert_buffer->scan_mask, indio_dev->masklength);
 677                 scan_timestamp |= insert_buffer->scan_timestamp;
 678         }
 679
 680         if (indio_dev->available_scan_masks) {
 681                 scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 682                                     indio_dev->masklength,
 683                                     compound_mask,
 684                                     strict_scanmask);
 685                 kfree(compound_mask);
 686                 if (scan_mask == NULL)
 687                         return -EINVAL;
 688         } else {
 689             scan_mask = compound_mask;
 690         }
 691
 692         config->scan_bytes = iio_compute_scan_bytes(indio_dev,
 693                                     scan_mask, scan_timestamp);
 694         config->scan_mask = scan_mask;
 695         config->scan_timestamp = scan_timestamp;
 696
 697         return 0;
 698 }
 699
 700 static int iio_enable_buffers(struct iio_dev *indio_dev,
 701         struct iio_device_config *config)
 702 {
 703         int ret;
 704
 705         indio_dev->active_scan_mask = config->scan_mask;
 706         indio_dev->scan_timestamp = config->scan_timestamp;
 707         indio_dev->scan_bytes = config->scan_bytes;
 708
 709         iio_update_demux(indio_dev);
 710
 711         /* Wind up again */
 712         if (indio_dev->setup_ops->preenable) {
 713                 ret = indio_dev->setup_ops->preenable(indio_dev);
 714                 if (ret) {
 715                         dev_dbg(&indio_dev->dev,
 716                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 717                         goto err_undo_config;
 718                 }
 719         }
 720
 721         if (indio_dev->info->update_scan_mode) {
 722                 ret = indio_dev->info
 723                         ->update_scan_mode(indio_dev,
 724                                            indio_dev->active_scan_mask);
 725                 if (ret < 0) {
 726                         dev_dbg(&indio_dev->dev,
 727                                 "Buffer not started: update scan mode failed (%d)\n",
 728                                 ret);
 729                         goto err_run_postdisable;
 730                 }
 731         }
 732
 733         indio_dev->currentmode = config->mode;
 734
 735         if (indio_dev->setup_ops->postenable) {
 736                 ret = indio_dev->setup_ops->postenable(indio_dev);
 737                 if (ret) {
 738                         dev_dbg(&indio_dev->dev,
 739                                "Buffer not started: postenable failed (%d)\n", ret);
 740                         goto err_run_postdisable;
 741                 }
 742         }
 743
 744         return 0;
 745
 746 err_run_postdisable:
 747         indio_dev->currentmode = INDIO_DIRECT_MODE;
 748         if (indio_dev->setup_ops->postdisable)
 749                 indio_dev->setup_ops->postdisable(indio_dev);
 750 err_undo_config:
 751         indio_dev->active_scan_mask = NULL;
 752
 753         return ret;
 754 }
 755
 756 static int iio_disable_buffers(struct iio_dev *indio_dev)
 757 {
 758         int ret = 0;
 759         int ret2;
 760
 761         /* Wind down existing buffers - iff there are any */
 762         if (list_empty(&indio_dev->buffer_list))
 763                 return 0;
 764
 765         /*
 766          * If things go wrong at some step in disable we still need to continue
 767          * to perform the other steps, otherwise we leave the device in a
 768          * inconsistent state. We return the error code for the first error we
 769          * encountered.
 770          */
 771
 772         if (indio_dev->setup_ops->predisable) {
 773                 ret2 = indio_dev->setup_ops->predisable(indio_dev);
 774                 if (ret2 && !ret)
 775                         ret = ret2;
 776         }
 777
 778         indio_dev->currentmode = INDIO_DIRECT_MODE;
 779
 780         if (indio_dev->setup_ops->postdisable) {
 781                 ret2 = indio_dev->setup_ops->postdisable(indio_dev);
 782                 if (ret2 && !ret)
 783                         ret = ret2;
 784         }
 785
 786         iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
 787         indio_dev->active_scan_mask = NULL;
 788
 789         return ret;
 790 }
 791
 792 static int __iio_update_buffers(struct iio_dev *indio_dev,
 793                        struct iio_buffer *insert_buffer,
 794                        struct iio_buffer *remove_buffer)
 795 {
 796         struct iio_device_config new_config;
 797         int ret;
 798
 799         ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
 800                 &new_config);
 801         if (ret)
 802                 return ret;
 803
 804         if (insert_buffer) {
 805                 ret = iio_buffer_request_update(indio_dev, insert_buffer);
 806                 if (ret)
 807                         goto err_free_config;
 808         }
 809
 810         ret = iio_disable_buffers(indio_dev);
 811         if (ret)
 812                 goto err_deactivate_all;
 813
 814         if (remove_buffer)
 815                 iio_buffer_deactivate(remove_buffer);
 816         if (insert_buffer)
 817                 iio_buffer_activate(indio_dev, insert_buffer);
 818
 819         /* If no buffers in list, we are done */
 820         if (list_empty(&indio_dev->buffer_list))
 821                 return 0;
 822
 823         ret = iio_enable_buffers(indio_dev, &new_config);
 824         if (ret)
 825                 goto err_deactivate_all;
 826
 827         return 0;
 828
 829 err_deactivate_all:
 830         /*
 831          * We've already verified that the config is valid earlier. If things go
 832          * wrong in either enable or disable the most likely reason is an IO
 833          * error from the device. In this case there is no good recovery
 834          * strategy. Just make sure to disable everything and leave the device
 835          * in a sane state.  With a bit of luck the device might come back to
 836          * life again later and userspace can try again.
 837          */
 838         iio_buffer_deactivate_all(indio_dev);
 839
 840 err_free_config:
 841         iio_free_scan_mask(indio_dev, new_config.scan_mask);
 842         return ret;
 843 }
 844
 845 int iio_update_buffers(struct iio_dev *indio_dev,
 846                        struct iio_buffer *insert_buffer,
 847                        struct iio_buffer *remove_buffer)
 848 {
 849         int ret;
 850
 851         if (insert_buffer == remove_buffer)
 852                 return 0;
 853
 854         mutex_lock(&indio_dev->info_exist_lock);
 855         mutex_lock(&indio_dev->mlock);
 856
 857         if (insert_buffer && iio_buffer_is_active(insert_buffer))
 858                 insert_buffer = NULL;
 859
 860         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
 861                 remove_buffer = NULL;
 862
 863         if (!insert_buffer && !remove_buffer) {
 864                 ret = 0;
 865                 goto out_unlock;
 866         }
 867
 868         if (indio_dev->info == NULL) {
 869                 ret = -ENODEV;
 870                 goto out_unlock;
 871         }
 872
 873         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 874
 875 out_unlock:
 876         mutex_unlock(&indio_dev->mlock);
 877         mutex_unlock(&indio_dev->info_exist_lock);
 878
 879         return ret;
 880 }
 881 EXPORT_SYMBOL_GPL(iio_update_buffers);
 882
 883 void iio_disable_all_buffers(struct iio_dev *indio_dev)
 884 {
 885         iio_disable_buffers(indio_dev);
 886         iio_buffer_deactivate_all(indio_dev);
 887 }
 888
 889 static ssize_t iio_buffer_store_enable(struct device *dev,
 890                                        struct device_attribute *attr,
 891                                        const char *buf,
 892                                        size_t len)
 893 {
 894         int ret;
 895         bool requested_state;
 896         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 897         bool inlist;
 898
 899         ret = strtobool(buf, &requested_state);
 900         if (ret < 0)
 901                 return ret;
 902
 903         mutex_lock(&indio_dev->mlock);
 904
 905         /* Find out if it is in the list */
 906         inlist = iio_buffer_is_active(indio_dev->buffer);
 907         /* Already in desired state */
 908         if (inlist == requested_state)
 909                 goto done;
 910
 911         if (requested_state)
 912                 ret = __iio_update_buffers(indio_dev,
 913                                          indio_dev->buffer, NULL);
 914         else
 915                 ret = __iio_update_buffers(indio_dev,
 916                                          NULL, indio_dev->buffer);
 917
 918 done:
 919         mutex_unlock(&indio_dev->mlock);
 920         return (ret < 0) ? ret : len;
 921 }
 922
 923 static const char * const iio_scan_elements_group_name = "scan_elements";
 924
 925 static ssize_t iio_buffer_show_watermark(struct device *dev,
 926                                          struct device_attribute *attr,
 927                                          char *buf)
 928 {
 929         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 930         struct iio_buffer *buffer = indio_dev->buffer;
 931
 932         return sprintf(buf, "%u\n", buffer->watermark);
 933 }
 934
 935 static ssize_t iio_buffer_store_watermark(struct device *dev,
 936                                           struct device_attribute *attr,
 937                                           const char *buf,
 938                                           size_t len)
 939 {
 940         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 941         struct iio_buffer *buffer = indio_dev->buffer;
 942         unsigned int val;
 943         int ret;
 944
 945         ret = kstrtouint(buf, 10, &val);
 946         if (ret)
 947                 return ret;
 948         if (!val)
 949                 return -EINVAL;
 950
 951         mutex_lock(&indio_dev->mlock);
 952
 953         if (val > buffer->length) {
 954                 ret = -EINVAL;
 955                 goto out;
 956         }
 957
 958         if (iio_buffer_is_active(indio_dev->buffer)) {
 959                 ret = -EBUSY;
 960                 goto out;
 961         }
 962
 963         buffer->watermark = val;
 964
 965         if (indio_dev->info->hwfifo_set_watermark)
 966                 indio_dev->info->hwfifo_set_watermark(indio_dev, val);
 967 out:
 968         mutex_unlock(&indio_dev->mlock);
 969
 970         return ret ? ret : len;
 971 }
 972
 973 static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
 974                    iio_buffer_write_length);
 975 static struct device_attribute dev_attr_length_ro = __ATTR(length,
 976         S_IRUGO, iio_buffer_read_length, NULL);
 977 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
 978                    iio_buffer_show_enable, iio_buffer_store_enable);
 979 static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
 980                    iio_buffer_show_watermark, iio_buffer_store_watermark);
 981
 982 static struct attribute *iio_buffer_attrs[] = {
 983         &dev_attr_length.attr,
 984         &dev_attr_enable.attr,
 985         &dev_attr_watermark.attr,
 986 };
 987
 988 int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
 989 {
 990         struct iio_dev_attr *p;
 991         struct attribute **attr;
 992         struct iio_buffer *buffer = indio_dev->buffer;
 993         int ret, i, attrn, attrcount, attrcount_orig = 0;
 994         const struct iio_chan_spec *channels;
 995
 996         channels = indio_dev->channels;
 997         if (channels) {
 998                 int ml = indio_dev->masklength;
 999
1000                 for (i = 0; i < indio_dev->num_channels; i++)
1001                         ml = max(ml, channels[i].scan_index + 1);
1002                 indio_dev->masklength = ml;
1003         }
1004
1005         if (!buffer)
1006                 return 0;
1007
1008         attrcount = 0;
1009         if (buffer->attrs) {
1010                 while (buffer->attrs[attrcount] != NULL)
1011                         attrcount++;
1012         }
1013
1014         attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
1015                        sizeof(struct attribute *), GFP_KERNEL);
1016         if (!attr)
1017                 return -ENOMEM;
1018
1019         memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1020         if (!buffer->access->set_length)
1021                 attr[0] = &dev_attr_length_ro.attr;
1022
1023         if (buffer->attrs)
1024                 memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
1025                        sizeof(struct attribute *) * attrcount);
1026
1027         attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
1028
1029         buffer->buffer_group.name = "buffer";
1030         buffer->buffer_group.attrs = attr;
1031
1032         indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
1033
1034         if (buffer->scan_el_attrs != NULL) {
1035                 attr = buffer->scan_el_attrs->attrs;
1036                 while (*attr++ != NULL)
1037                         attrcount_orig++;
1038         }
1039         attrcount = attrcount_orig;
1040         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
1041         channels = indio_dev->channels;
1042         if (channels) {
1043                 /* new magic */
1044                 for (i = 0; i < indio_dev->num_channels; i++) {
1045                         if (channels[i].scan_index < 0)
1046                                 continue;
1047
1048                         ret = iio_buffer_add_channel_sysfs(indio_dev,
1049                                                          &channels[i]);
1050                         if (ret < 0)
1051                                 goto error_cleanup_dynamic;
1052                         attrcount += ret;
1053                         if (channels[i].type == IIO_TIMESTAMP)
1054                                 indio_dev->scan_index_timestamp =
1055                                         channels[i].scan_index;
1056                 }
1057                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
1058                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
1059                                                     sizeof(*buffer->scan_mask),
1060                                                     GFP_KERNEL);
1061                         if (buffer->scan_mask == NULL) {
1062                                 ret = -ENOMEM;
1063                                 goto error_cleanup_dynamic;
1064                         }
1065                 }
1066         }
1067
1068         buffer->scan_el_group.name = iio_scan_elements_group_name;
1069
1070         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
1071                                               sizeof(buffer->scan_el_group.attrs[0]),
1072                                               GFP_KERNEL);
1073         if (buffer->scan_el_group.attrs == NULL) {
1074                 ret = -ENOMEM;
1075                 goto error_free_scan_mask;
1076         }
1077         if (buffer->scan_el_attrs)
1078                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
1079                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
1080         attrn = attrcount_orig;
1081
1082         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
1083                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
1084         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
1085
1086         return 0;
1087
1088 error_free_scan_mask:
1089         kfree(buffer->scan_mask);
1090 error_cleanup_dynamic:
1091         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
1092         kfree(indio_dev->buffer->buffer_group.attrs);
1093
1094         return ret;
1095 }
1096
1097 void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
1098 {
1099         if (!indio_dev->buffer)
1100                 return;
1101
1102         kfree(indio_dev->buffer->scan_mask);
1103         kfree(indio_dev->buffer->buffer_group.attrs);
1104         kfree(indio_dev->buffer->scan_el_group.attrs);
1105         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
1106 }
1107
1108 /**
1109  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1110  * @indio_dev: the iio device
1111  * @mask: scan mask to be checked
1112  *
1113  * Return true if exactly one bit is set in the scan mask, false otherwise. It
1114  * can be used for devices where only one channel can be active for sampling at
1115  * a time.
1116  */
1117 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1118         const unsigned long *mask)
1119 {
1120         return bitmap_weight(mask, indio_dev->masklength) == 1;
1121 }
1122 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1123
1124 int iio_scan_mask_query(struct iio_dev *indio_dev,
1125                         struct iio_buffer *buffer, int bit)
1126 {
1127         if (bit > indio_dev->masklength)
1128                 return -EINVAL;
1129
1130         if (!buffer->scan_mask)
1131                 return 0;
1132
1133         /* Ensure return value is 0 or 1. */
1134         return !!test_bit(bit, buffer->scan_mask);
1135 };
1136 EXPORT_SYMBOL_GPL(iio_scan_mask_query);
1137
1138 /**
1139  * struct iio_demux_table() - table describing demux memcpy ops
1140  * @from:       index to copy from
1141  * @to:         index to copy to
1142  * @length:     how many bytes to copy
1143  * @l:          list head used for management
1144  */
1145 struct iio_demux_table {
1146         unsigned from;
1147         unsigned to;
1148         unsigned length;
1149         struct list_head l;
1150 };
1151
1152 static const void *iio_demux(struct iio_buffer *buffer,
1153                                  const void *datain)
1154 {
1155         struct iio_demux_table *t;
1156
1157         if (list_empty(&buffer->demux_list))
1158                 return datain;
1159         list_for_each_entry(t, &buffer->demux_list, l)
1160                 memcpy(buffer->demux_bounce + t->to,
1161                        datain + t->from, t->length);
1162
1163         return buffer->demux_bounce;
1164 }
1165
1166 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1167 {
1168         const void *dataout = iio_demux(buffer, data);
1169         int ret;
1170
1171         ret = buffer->access->store_to(buffer, dataout);
1172         if (ret)
1173                 return ret;
1174
1175         /*
1176          * We can't just test for watermark to decide if we wake the poll queue
1177          * because read may request less samples than the watermark.
1178          */
1179         wake_up_interruptible_poll(&buffer->pollq, POLLIN | POLLRDNORM);
1180         return 0;
1181 }
1182
1183 static void iio_buffer_demux_free(struct iio_buffer *buffer)
1184 {
1185         struct iio_demux_table *p, *q;
1186         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
1187                 list_del(&p->l);
1188                 kfree(p);
1189         }
1190 }
1191
1192
1193 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1194 {
1195         int ret;
1196         struct iio_buffer *buf;
1197
1198         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
1199                 ret = iio_push_to_buffer(buf, data);
1200                 if (ret < 0)
1201                         return ret;
1202         }
1203
1204         return 0;
1205 }
1206 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1207
1208 static int iio_buffer_add_demux(struct iio_buffer *buffer,
1209         struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
1210         unsigned int length)
1211 {
1212
1213         if (*p && (*p)->from + (*p)->length == in_loc &&
1214                 (*p)->to + (*p)->length == out_loc) {
1215                 (*p)->length += length;
1216         } else {
1217                 *p = kmalloc(sizeof(**p), GFP_KERNEL);
1218                 if (*p == NULL)
1219                         return -ENOMEM;
1220                 (*p)->from = in_loc;
1221                 (*p)->to = out_loc;
1222                 (*p)->length = length;
1223                 list_add_tail(&(*p)->l, &buffer->demux_list);
1224         }
1225
1226         return 0;
1227 }
1228
1229 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
1230                                    struct iio_buffer *buffer)
1231 {
1232         const struct iio_chan_spec *ch;
1233         int ret, in_ind = -1, out_ind, length;
1234         unsigned in_loc = 0, out_loc = 0;
1235         struct iio_demux_table *p = NULL;
1236
1237         /* Clear out any old demux */
1238         iio_buffer_demux_free(buffer);
1239         kfree(buffer->demux_bounce);
1240         buffer->demux_bounce = NULL;
1241
1242         /* First work out which scan mode we will actually have */
1243         if (bitmap_equal(indio_dev->active_scan_mask,
1244                          buffer->scan_mask,
1245                          indio_dev->masklength))
1246                 return 0;
1247
1248         /* Now we have the two masks, work from least sig and build up sizes */
1249         for_each_set_bit(out_ind,
1250                          buffer->scan_mask,
1251                          indio_dev->masklength) {
1252                 in_ind = find_next_bit(indio_dev->active_scan_mask,
1253                                        indio_dev->masklength,
1254                                        in_ind + 1);
1255                 while (in_ind != out_ind) {
1256                         in_ind = find_next_bit(indio_dev->active_scan_mask,
1257                                                indio_dev->masklength,
1258                                                in_ind + 1);
1259                         ch = iio_find_channel_from_si(indio_dev, in_ind);
1260                         if (ch->scan_type.repeat > 1)
1261                                 length = ch->scan_type.storagebits / 8 *
1262                                         ch->scan_type.repeat;
1263                         else
1264                                 length = ch->scan_type.storagebits / 8;
1265                         /* Make sure we are aligned */
1266                         in_loc = roundup(in_loc, length) + length;
1267                 }
1268                 ch = iio_find_channel_from_si(indio_dev, in_ind);
1269                 if (ch->scan_type.repeat > 1)
1270                         length = ch->scan_type.storagebits / 8 *
1271                                 ch->scan_type.repeat;
1272                 else
1273                         length = ch->scan_type.storagebits / 8;
1274                 out_loc = roundup(out_loc, length);
1275                 in_loc = roundup(in_loc, length);
1276                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
1277                 if (ret)
1278                         goto error_clear_mux_table;
1279                 out_loc += length;
1280                 in_loc += length;
1281         }
1282         /* Relies on scan_timestamp being last */
1283         if (buffer->scan_timestamp) {
1284                 ch = iio_find_channel_from_si(indio_dev,
1285                         indio_dev->scan_index_timestamp);
1286                 if (ch->scan_type.repeat > 1)
1287                         length = ch->scan_type.storagebits / 8 *
1288                                 ch->scan_type.repeat;
1289                 else
1290                         length = ch->scan_type.storagebits / 8;
1291                 out_loc = roundup(out_loc, length);
1292                 in_loc = roundup(in_loc, length);
1293                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
1294                 if (ret)
1295                         goto error_clear_mux_table;
1296                 out_loc += length;
1297                 in_loc += length;
1298         }
1299         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
1300         if (buffer->demux_bounce == NULL) {
1301                 ret = -ENOMEM;
1302                 goto error_clear_mux_table;
1303         }
1304         return 0;
1305
1306 error_clear_mux_table:
1307         iio_buffer_demux_free(buffer);
1308
1309         return ret;
1310 }
1311
1312 int iio_update_demux(struct iio_dev *indio_dev)
1313 {
1314         struct iio_buffer *buffer;
1315         int ret;
1316
1317         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1318                 ret = iio_buffer_update_demux(indio_dev, buffer);
1319                 if (ret < 0)
1320                         goto error_clear_mux_table;
1321         }
1322         return 0;
1323
1324 error_clear_mux_table:
1325         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
1326                 iio_buffer_demux_free(buffer);
1327
1328         return ret;
1329 }
1330 EXPORT_SYMBOL_GPL(iio_update_demux);
1331
1332 /**
1333  * iio_buffer_release() - Free a buffer's resources
1334  * @ref: Pointer to the kref embedded in the iio_buffer struct
1335  *
1336  * This function is called when the last reference to the buffer has been
1337  * dropped. It will typically free all resources allocated by the buffer. Do not
1338  * call this function manually, always use iio_buffer_put() when done using a
1339  * buffer.
1340  */
1341 static void iio_buffer_release(struct kref *ref)
1342 {
1343         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1344
1345         buffer->access->release(buffer);
1346 }
1347
1348 /**
1349  * iio_buffer_get() - Grab a reference to the buffer
1350  * @buffer: The buffer to grab a reference for, may be NULL
1351  *
1352  * Returns the pointer to the buffer that was passed into the function.
1353  */
1354 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1355 {
1356         if (buffer)
1357                 kref_get(&buffer->ref);
1358
1359         return buffer;
1360 }
1361 EXPORT_SYMBOL_GPL(iio_buffer_get);
1362
1363 /**
1364  * iio_buffer_put() - Release the reference to the buffer
1365  * @buffer: The buffer to release the reference for, may be NULL
1366  */
1367 void iio_buffer_put(struct iio_buffer *buffer)
1368 {
1369         if (buffer)
1370                 kref_put(&buffer->ref, iio_buffer_release);
1371 }
1372 EXPORT_SYMBOL_GPL(iio_buffer_put);