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,
  76                                                 to_flush - avail);
  77                 return true;
  78         }
  79
  80         if (to_flush)
  81                 flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
  82                                                   to_wait - avail);
  83         if (flushed <= 0)
  84                 return false;
  85
  86         if (avail + flushed >= to_wait)
  87                 return true;
  88
  89         return false;
  90 }
  91
  92 /**
  93  * iio_buffer_read_first_n_outer() - chrdev read for buffer access
  94  * @filp:       File structure pointer for the char device
  95  * @buf:        Destination buffer for iio buffer read
  96  * @n:          First n bytes to read
  97  * @f_ps:       Long offset provided by the user as a seek position
  98  *
  99  * This function relies on all buffer implementations having an
 100  * iio_buffer as their first element.
 101  *
 102  * Return: negative values corresponding to error codes or ret != 0
 103  *         for ending the reading activity
 104  **/
 105 ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
 106                                       size_t n, loff_t *f_ps)
 107 {
 108         struct iio_dev *indio_dev = filp->private_data;
 109         struct iio_buffer *rb = indio_dev->buffer;
 110         size_t datum_size;
 111         size_t to_wait;
 112         int ret;
 113
 114         if (!indio_dev->info)
 115                 return -ENODEV;
 116
 117         if (!rb || !rb->access->read_first_n)
 118                 return -EINVAL;
 119
 120         datum_size = rb->bytes_per_datum;
 121
 122         /*
 123          * If datum_size is 0 there will never be anything to read from the
 124          * buffer, so signal end of file now.
 125          */
 126         if (!datum_size)
 127                 return 0;
 128
 129         if (filp->f_flags & O_NONBLOCK)
 130                 to_wait = 0;
 131         else
 132                 to_wait = min_t(size_t, n / datum_size, rb->watermark);
 133
 134         do {
 135                 ret = wait_event_interruptible(rb->pollq,
 136                       iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size));
 137                 if (ret)
 138                         return ret;
 139
 140                 if (!indio_dev->info)
 141                         return -ENODEV;
 142
 143                 ret = rb->access->read_first_n(rb, n, buf);
 144                 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
 145                         ret = -EAGAIN;
 146          } while (ret == 0);
 147
 148         return ret;
 149 }
 150
 151 /**
 152  * iio_buffer_poll() - poll the buffer to find out if it has data
 153  * @filp:       File structure pointer for device access
 154  * @wait:       Poll table structure pointer for which the driver adds
 155  *              a wait queue
 156  *
 157  * Return: (POLLIN | POLLRDNORM) if data is available for reading
 158  *         or 0 for other cases
 159  */
 160 unsigned int iio_buffer_poll(struct file *filp,
 161                              struct poll_table_struct *wait)
 162 {
 163         struct iio_dev *indio_dev = filp->private_data;
 164         struct iio_buffer *rb = indio_dev->buffer;
 165
 166         if (!indio_dev->info)
 167                 return 0;
 168
 169         poll_wait(filp, &rb->pollq, wait);
 170         if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0))
 171                 return POLLIN | POLLRDNORM;
 172         return 0;
 173 }
 174
 175 /**
 176  * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
 177  * @indio_dev: The IIO device
 178  *
 179  * Wakes up the event waitqueue used for poll(). Should usually
 180  * be called when the device is unregistered.
 181  */
 182 void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
 183 {
 184         if (!indio_dev->buffer)
 185                 return;
 186
 187         wake_up(&indio_dev->buffer->pollq);
 188 }
 189
 190 void iio_buffer_init(struct iio_buffer *buffer)
 191 {
 192         INIT_LIST_HEAD(&buffer->demux_list);
 193         INIT_LIST_HEAD(&buffer->buffer_list);
 194         init_waitqueue_head(&buffer->pollq);
 195         kref_init(&buffer->ref);
 196         if (!buffer->watermark)
 197                 buffer->watermark = 1;
 198 }
 199 EXPORT_SYMBOL(iio_buffer_init);
 200
 201 static ssize_t iio_show_scan_index(struct device *dev,
 202                                    struct device_attribute *attr,
 203                                    char *buf)
 204 {
 205         return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
 206 }
 207
 208 static ssize_t iio_show_fixed_type(struct device *dev,
 209                                    struct device_attribute *attr,
 210                                    char *buf)
 211 {
 212         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 213         u8 type = this_attr->c->scan_type.endianness;
 214
 215         if (type == IIO_CPU) {
 216 #ifdef __LITTLE_ENDIAN
 217                 type = IIO_LE;
 218 #else
 219                 type = IIO_BE;
 220 #endif
 221         }
 222         if (this_attr->c->scan_type.repeat > 1)
 223                 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
 224                        iio_endian_prefix[type],
 225                        this_attr->c->scan_type.sign,
 226                        this_attr->c->scan_type.realbits,
 227                        this_attr->c->scan_type.storagebits,
 228                        this_attr->c->scan_type.repeat,
 229                        this_attr->c->scan_type.shift);
 230                 else
 231                         return sprintf(buf, "%s:%c%d/%d>>%u\n",
 232                        iio_endian_prefix[type],
 233                        this_attr->c->scan_type.sign,
 234                        this_attr->c->scan_type.realbits,
 235                        this_attr->c->scan_type.storagebits,
 236                        this_attr->c->scan_type.shift);
 237 }
 238
 239 static ssize_t iio_scan_el_show(struct device *dev,
 240                                 struct device_attribute *attr,
 241                                 char *buf)
 242 {
 243         int ret;
 244         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 245
 246         /* Ensure ret is 0 or 1. */
 247         ret = !!test_bit(to_iio_dev_attr(attr)->address,
 248                        indio_dev->buffer->scan_mask);
 249
 250         return sprintf(buf, "%d\n", ret);
 251 }
 252
 253 /* Note NULL used as error indicator as it doesn't make sense. */
 254 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
 255                                           unsigned int masklength,
 256                                           const unsigned long *mask,
 257                                           bool strict)
 258 {
 259         if (bitmap_empty(mask, masklength))
 260                 return NULL;
 261         while (*av_masks) {
 262                 if (strict) {
 263                         if (bitmap_equal(mask, av_masks, masklength))
 264                                 return av_masks;
 265                 } else {
 266                         if (bitmap_subset(mask, av_masks, masklength))
 267                                 return av_masks;
 268                 }
 269                 av_masks += BITS_TO_LONGS(masklength);
 270         }
 271         return NULL;
 272 }
 273
 274 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
 275         const unsigned long *mask)
 276 {
 277         if (!indio_dev->setup_ops->validate_scan_mask)
 278                 return true;
 279
 280         return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
 281 }
 282
 283 /**
 284  * iio_scan_mask_set() - set particular bit in the scan mask
 285  * @indio_dev: the iio device
 286  * @buffer: the buffer whose scan mask we are interested in
 287  * @bit: the bit to be set.
 288  *
 289  * Note that at this point we have no way of knowing what other
 290  * buffers might request, hence this code only verifies that the
 291  * individual buffers request is plausible.
 292  */
 293 static int iio_scan_mask_set(struct iio_dev *indio_dev,
 294                       struct iio_buffer *buffer, int bit)
 295 {
 296         const unsigned long *mask;
 297         unsigned long *trialmask;
 298
 299         trialmask = kmalloc(sizeof(*trialmask)*
 300                             BITS_TO_LONGS(indio_dev->masklength),
 301                             GFP_KERNEL);
 302
 303         if (trialmask == NULL)
 304                 return -ENOMEM;
 305         if (!indio_dev->masklength) {
 306                 WARN(1, "Trying to set scanmask prior to registering buffer\n");
 307                 goto err_invalid_mask;
 308         }
 309         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 310         set_bit(bit, trialmask);
 311
 312         if (!iio_validate_scan_mask(indio_dev, trialmask))
 313                 goto err_invalid_mask;
 314
 315         if (indio_dev->available_scan_masks) {
 316                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 317                                            indio_dev->masklength,
 318                                            trialmask, false);
 319                 if (!mask)
 320                         goto err_invalid_mask;
 321         }
 322         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 323
 324         kfree(trialmask);
 325
 326         return 0;
 327
 328 err_invalid_mask:
 329         kfree(trialmask);
 330         return -EINVAL;
 331 }
 332
 333 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 334 {
 335         clear_bit(bit, buffer->scan_mask);
 336         return 0;
 337 }
 338
 339 static ssize_t iio_scan_el_store(struct device *dev,
 340                                  struct device_attribute *attr,
 341                                  const char *buf,
 342                                  size_t len)
 343 {
 344         int ret;
 345         bool state;
 346         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 347         struct iio_buffer *buffer = indio_dev->buffer;
 348         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 349
 350         ret = strtobool(buf, &state);
 351         if (ret < 0)
 352                 return ret;
 353         mutex_lock(&indio_dev->mlock);
 354         if (iio_buffer_is_active(indio_dev->buffer)) {
 355                 ret = -EBUSY;
 356                 goto error_ret;
 357         }
 358         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 359         if (ret < 0)
 360                 goto error_ret;
 361         if (!state && ret) {
 362                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 363                 if (ret)
 364                         goto error_ret;
 365         } else if (state && !ret) {
 366                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 367                 if (ret)
 368                         goto error_ret;
 369         }
 370
 371 error_ret:
 372         mutex_unlock(&indio_dev->mlock);
 373
 374         return ret < 0 ? ret : len;
 375
 376 }
 377
 378 static ssize_t iio_scan_el_ts_show(struct device *dev,
 379                                    struct device_attribute *attr,
 380                                    char *buf)
 381 {
 382         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 383         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 384 }
 385
 386 static ssize_t iio_scan_el_ts_store(struct device *dev,
 387                                     struct device_attribute *attr,
 388                                     const char *buf,
 389                                     size_t len)
 390 {
 391         int ret;
 392         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 393         bool state;
 394
 395         ret = strtobool(buf, &state);
 396         if (ret < 0)
 397                 return ret;
 398
 399         mutex_lock(&indio_dev->mlock);
 400         if (iio_buffer_is_active(indio_dev->buffer)) {
 401                 ret = -EBUSY;
 402                 goto error_ret;
 403         }
 404         indio_dev->buffer->scan_timestamp = state;
 405 error_ret:
 406         mutex_unlock(&indio_dev->mlock);
 407
 408         return ret ? ret : len;
 409 }
 410
 411 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 412                                         const struct iio_chan_spec *chan)
 413 {
 414         int ret, attrcount = 0;
 415         struct iio_buffer *buffer = indio_dev->buffer;
 416
 417         ret = __iio_add_chan_devattr("index",
 418                                      chan,
 419                                      &iio_show_scan_index,
 420                                      NULL,
 421                                      0,
 422                                      IIO_SEPARATE,
 423                                      &indio_dev->dev,
 424                                      &buffer->scan_el_dev_attr_list);
 425         if (ret)
 426                 return ret;
 427         attrcount++;
 428         ret = __iio_add_chan_devattr("type",
 429                                      chan,
 430                                      &iio_show_fixed_type,
 431                                      NULL,
 432                                      0,
 433                                      0,
 434                                      &indio_dev->dev,
 435                                      &buffer->scan_el_dev_attr_list);
 436         if (ret)
 437                 return ret;
 438         attrcount++;
 439         if (chan->type != IIO_TIMESTAMP)
 440                 ret = __iio_add_chan_devattr("en",
 441                                              chan,
 442                                              &iio_scan_el_show,
 443                                              &iio_scan_el_store,
 444                                              chan->scan_index,
 445                                              0,
 446                                              &indio_dev->dev,
 447                                              &buffer->scan_el_dev_attr_list);
 448         else
 449                 ret = __iio_add_chan_devattr("en",
 450                                              chan,
 451                                              &iio_scan_el_ts_show,
 452                                              &iio_scan_el_ts_store,
 453                                              chan->scan_index,
 454                                              0,
 455                                              &indio_dev->dev,
 456                                              &buffer->scan_el_dev_attr_list);
 457         if (ret)
 458                 return ret;
 459         attrcount++;
 460         ret = attrcount;
 461         return ret;
 462 }
 463
 464 static ssize_t iio_buffer_read_length(struct device *dev,
 465                                       struct device_attribute *attr,
 466                                       char *buf)
 467 {
 468         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 469         struct iio_buffer *buffer = indio_dev->buffer;
 470
 471         return sprintf(buf, "%d\n", buffer->length);
 472 }
 473
 474 static ssize_t iio_buffer_write_length(struct device *dev,
 475                                        struct device_attribute *attr,
 476                                        const char *buf, size_t len)
 477 {
 478         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 479         struct iio_buffer *buffer = indio_dev->buffer;
 480         unsigned int val;
 481         int ret;
 482
 483         ret = kstrtouint(buf, 10, &val);
 484         if (ret)
 485                 return ret;
 486
 487         if (val == buffer->length)
 488                 return len;
 489
 490         mutex_lock(&indio_dev->mlock);
 491         if (iio_buffer_is_active(indio_dev->buffer)) {
 492                 ret = -EBUSY;
 493         } else {
 494                 buffer->access->set_length(buffer, val);
 495                 ret = 0;
 496         }
 497         if (ret)
 498                 goto out;
 499         if (buffer->length && buffer->length < buffer->watermark)
 500                 buffer->watermark = buffer->length;
 501 out:
 502         mutex_unlock(&indio_dev->mlock);
 503
 504         return ret ? ret : len;
 505 }
 506
 507 static ssize_t iio_buffer_show_enable(struct device *dev,
 508                                       struct device_attribute *attr,
 509                                       char *buf)
 510 {
 511         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 512         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 513 }
 514
 515 static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
 516                                              unsigned int scan_index)
 517 {
 518         const struct iio_chan_spec *ch;
 519         unsigned int bytes;
 520
 521         ch = iio_find_channel_from_si(indio_dev, scan_index);
 522         bytes = ch->scan_type.storagebits / 8;
 523         if (ch->scan_type.repeat > 1)
 524                 bytes *= ch->scan_type.repeat;
 525         return bytes;
 526 }
 527
 528 static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
 529 {
 530         return iio_storage_bytes_for_si(indio_dev,
 531                                         indio_dev->scan_index_timestamp);
 532 }
 533
 534 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 535                                 const unsigned long *mask, bool timestamp)
 536 {
 537         unsigned bytes = 0;
 538         int length, i;
 539
 540         /* How much space will the demuxed element take? */
 541         for_each_set_bit(i, mask,
 542                          indio_dev->masklength) {
 543                 length = iio_storage_bytes_for_si(indio_dev, i);
 544                 bytes = ALIGN(bytes, length);
 545                 bytes += length;
 546         }
 547
 548         if (timestamp) {
 549                 length = iio_storage_bytes_for_timestamp(indio_dev);
 550                 bytes = ALIGN(bytes, length);
 551                 bytes += length;
 552         }
 553         return bytes;
 554 }
 555
 556 static void iio_buffer_activate(struct iio_dev *indio_dev,
 557         struct iio_buffer *buffer)
 558 {
 559         iio_buffer_get(buffer);
 560         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 561 }
 562
 563 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 564 {
 565         list_del_init(&buffer->buffer_list);
 566         wake_up_interruptible(&buffer->pollq);
 567         iio_buffer_put(buffer);
 568 }
 569
 570 static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
 571 {
 572         struct iio_buffer *buffer, *_buffer;
 573
 574         list_for_each_entry_safe(buffer, _buffer,
 575                         &indio_dev->buffer_list, buffer_list)
 576                 iio_buffer_deactivate(buffer);
 577 }
 578
 579 static int iio_buffer_enable(struct iio_buffer *buffer,
 580         struct iio_dev *indio_dev)
 581 {
 582         if (!buffer->access->enable)
 583                 return 0;
 584         return buffer->access->enable(buffer, indio_dev);
 585 }
 586
 587 static int iio_buffer_disable(struct iio_buffer *buffer,
 588         struct iio_dev *indio_dev)
 589 {
 590         if (!buffer->access->disable)
 591                 return 0;
 592         return buffer->access->disable(buffer, indio_dev);
 593 }
 594
 595 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 596         struct iio_buffer *buffer)
 597 {
 598         unsigned int bytes;
 599
 600         if (!buffer->access->set_bytes_per_datum)
 601                 return;
 602
 603         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 604                 buffer->scan_timestamp);
 605
 606         buffer->access->set_bytes_per_datum(buffer, bytes);
 607 }
 608
 609 static int iio_buffer_request_update(struct iio_dev *indio_dev,
 610         struct iio_buffer *buffer)
 611 {
 612         int ret;
 613
 614         iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 615         if (buffer->access->request_update) {
 616                 ret = buffer->access->request_update(buffer);
 617                 if (ret) {
 618                         dev_dbg(&indio_dev->dev,
 619                                "Buffer not started: buffer parameter update failed (%d)\n",
 620                                 ret);
 621                         return ret;
 622                 }
 623         }
 624
 625         return 0;
 626 }
 627
 628 static void iio_free_scan_mask(struct iio_dev *indio_dev,
 629         const unsigned long *mask)
 630 {
 631         /* If the mask is dynamically allocated free it, otherwise do nothing */
 632         if (!indio_dev->available_scan_masks)
 633                 kfree(mask);
 634 }
 635
 636 struct iio_device_config {
 637         unsigned int mode;
 638         unsigned int watermark;
 639         const unsigned long *scan_mask;
 640         unsigned int scan_bytes;
 641         bool scan_timestamp;
 642 };
 643
 644 static int iio_verify_update(struct iio_dev *indio_dev,
 645         struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
 646         struct iio_device_config *config)
 647 {
 648         unsigned long *compound_mask;
 649         const unsigned long *scan_mask;
 650         bool strict_scanmask = false;
 651         struct iio_buffer *buffer;
 652         bool scan_timestamp;
 653         unsigned int modes;
 654
 655         memset(config, 0, sizeof(*config));
 656
 657         /*
 658          * If there is just one buffer and we are removing it there is nothing
 659          * to verify.
 660          */
 661         if (remove_buffer && !insert_buffer &&
 662                 list_is_singular(&indio_dev->buffer_list))
 663                         return 0;
 664
 665         modes = indio_dev->modes;
 666
 667         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 668                 if (buffer == remove_buffer)
 669                         continue;
 670                 modes &= buffer->access->modes;
 671                 config->watermark = min(config->watermark, buffer->watermark);
 672         }
 673
 674         if (insert_buffer) {
 675                 modes &= insert_buffer->access->modes;
 676                 config->watermark = min(config->watermark,
 677                         insert_buffer->watermark);
 678         }
 679
 680         /* Definitely possible for devices to support both of these. */
 681         if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
 682                 config->mode = INDIO_BUFFER_TRIGGERED;
 683         } else if (modes & INDIO_BUFFER_HARDWARE) {
 684                 /*
 685                  * Keep things simple for now and only allow a single buffer to
 686                  * be connected in hardware mode.
 687                  */
 688                 if (insert_buffer && !list_empty(&indio_dev->buffer_list))
 689                         return -EINVAL;
 690                 config->mode = INDIO_BUFFER_HARDWARE;
 691                 strict_scanmask = true;
 692         } else if (modes & INDIO_BUFFER_SOFTWARE) {
 693                 config->mode = INDIO_BUFFER_SOFTWARE;
 694         } else {
 695                 /* Can only occur on first buffer */
 696                 if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
 697                         dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
 698                 return -EINVAL;
 699         }
 700
 701         /* What scan mask do we actually have? */
 702         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 703                                 sizeof(long), GFP_KERNEL);
 704         if (compound_mask == NULL)
 705                 return -ENOMEM;
 706
 707         scan_timestamp = false;
 708
 709         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 710                 if (buffer == remove_buffer)
 711                         continue;
 712                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 713                           indio_dev->masklength);
 714                 scan_timestamp |= buffer->scan_timestamp;
 715         }
 716
 717         if (insert_buffer) {
 718                 bitmap_or(compound_mask, compound_mask,
 719                           insert_buffer->scan_mask, indio_dev->masklength);
 720                 scan_timestamp |= insert_buffer->scan_timestamp;
 721         }
 722
 723         if (indio_dev->available_scan_masks) {
 724                 scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 725                                     indio_dev->masklength,
 726                                     compound_mask,
 727                                     strict_scanmask);
 728                 kfree(compound_mask);
 729                 if (scan_mask == NULL)
 730                         return -EINVAL;
 731         } else {
 732             scan_mask = compound_mask;
 733         }
 734
 735         config->scan_bytes = iio_compute_scan_bytes(indio_dev,
 736                                     scan_mask, scan_timestamp);
 737         config->scan_mask = scan_mask;
 738         config->scan_timestamp = scan_timestamp;
 739
 740         return 0;
 741 }
 742
 743 static int iio_enable_buffers(struct iio_dev *indio_dev,
 744         struct iio_device_config *config)
 745 {
 746         struct iio_buffer *buffer;
 747         int ret;
 748
 749         indio_dev->active_scan_mask = config->scan_mask;
 750         indio_dev->scan_timestamp = config->scan_timestamp;
 751         indio_dev->scan_bytes = config->scan_bytes;
 752
 753         iio_update_demux(indio_dev);
 754
 755         /* Wind up again */
 756         if (indio_dev->setup_ops->preenable) {
 757                 ret = indio_dev->setup_ops->preenable(indio_dev);
 758                 if (ret) {
 759                         dev_dbg(&indio_dev->dev,
 760                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 761                         goto err_undo_config;
 762                 }
 763         }
 764
 765         if (indio_dev->info->update_scan_mode) {
 766                 ret = indio_dev->info
 767                         ->update_scan_mode(indio_dev,
 768                                            indio_dev->active_scan_mask);
 769                 if (ret < 0) {
 770                         dev_dbg(&indio_dev->dev,
 771                                 "Buffer not started: update scan mode failed (%d)\n",
 772                                 ret);
 773                         goto err_run_postdisable;
 774                 }
 775         }
 776
 777         if (indio_dev->info->hwfifo_set_watermark)
 778                 indio_dev->info->hwfifo_set_watermark(indio_dev,
 779                         config->watermark);
 780
 781         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 782                 ret = iio_buffer_enable(buffer, indio_dev);
 783                 if (ret)
 784                         goto err_disable_buffers;
 785         }
 786
 787         indio_dev->currentmode = config->mode;
 788
 789         if (indio_dev->setup_ops->postenable) {
 790                 ret = indio_dev->setup_ops->postenable(indio_dev);
 791                 if (ret) {
 792                         dev_dbg(&indio_dev->dev,
 793                                "Buffer not started: postenable failed (%d)\n", ret);
 794                         goto err_disable_buffers;
 795                 }
 796         }
 797
 798         return 0;
 799
 800 err_disable_buffers:
 801         list_for_each_entry_continue_reverse(buffer, &indio_dev->buffer_list,
 802                                              buffer_list)
 803                 iio_buffer_disable(buffer, indio_dev);
 804 err_run_postdisable:
 805         indio_dev->currentmode = INDIO_DIRECT_MODE;
 806         if (indio_dev->setup_ops->postdisable)
 807                 indio_dev->setup_ops->postdisable(indio_dev);
 808 err_undo_config:
 809         indio_dev->active_scan_mask = NULL;
 810
 811         return ret;
 812 }
 813
 814 static int iio_disable_buffers(struct iio_dev *indio_dev)
 815 {
 816         struct iio_buffer *buffer;
 817         int ret = 0;
 818         int ret2;
 819
 820         /* Wind down existing buffers - iff there are any */
 821         if (list_empty(&indio_dev->buffer_list))
 822                 return 0;
 823
 824         /*
 825          * If things go wrong at some step in disable we still need to continue
 826          * to perform the other steps, otherwise we leave the device in a
 827          * inconsistent state. We return the error code for the first error we
 828          * encountered.
 829          */
 830
 831         if (indio_dev->setup_ops->predisable) {
 832                 ret2 = indio_dev->setup_ops->predisable(indio_dev);
 833                 if (ret2 && !ret)
 834                         ret = ret2;
 835         }
 836
 837         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 838                 ret2 = iio_buffer_disable(buffer, indio_dev);
 839                 if (ret2 && !ret)
 840                         ret = ret2;
 841         }
 842
 843         indio_dev->currentmode = INDIO_DIRECT_MODE;
 844
 845         if (indio_dev->setup_ops->postdisable) {
 846                 ret2 = indio_dev->setup_ops->postdisable(indio_dev);
 847                 if (ret2 && !ret)
 848                         ret = ret2;
 849         }
 850
 851         iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
 852         indio_dev->active_scan_mask = NULL;
 853
 854         return ret;
 855 }
 856
 857 static int __iio_update_buffers(struct iio_dev *indio_dev,
 858                        struct iio_buffer *insert_buffer,
 859                        struct iio_buffer *remove_buffer)
 860 {
 861         struct iio_device_config new_config;
 862         int ret;
 863
 864         ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
 865                 &new_config);
 866         if (ret)
 867                 return ret;
 868
 869         if (insert_buffer) {
 870                 ret = iio_buffer_request_update(indio_dev, insert_buffer);
 871                 if (ret)
 872                         goto err_free_config;
 873         }
 874
 875         ret = iio_disable_buffers(indio_dev);
 876         if (ret)
 877                 goto err_deactivate_all;
 878
 879         if (remove_buffer)
 880                 iio_buffer_deactivate(remove_buffer);
 881         if (insert_buffer)
 882                 iio_buffer_activate(indio_dev, insert_buffer);
 883
 884         /* If no buffers in list, we are done */
 885         if (list_empty(&indio_dev->buffer_list))
 886                 return 0;
 887
 888         ret = iio_enable_buffers(indio_dev, &new_config);
 889         if (ret)
 890                 goto err_deactivate_all;
 891
 892         return 0;
 893
 894 err_deactivate_all:
 895         /*
 896          * We've already verified that the config is valid earlier. If things go
 897          * wrong in either enable or disable the most likely reason is an IO
 898          * error from the device. In this case there is no good recovery
 899          * strategy. Just make sure to disable everything and leave the device
 900          * in a sane state.  With a bit of luck the device might come back to
 901          * life again later and userspace can try again.
 902          */
 903         iio_buffer_deactivate_all(indio_dev);
 904
 905 err_free_config:
 906         iio_free_scan_mask(indio_dev, new_config.scan_mask);
 907         return ret;
 908 }
 909
 910 int iio_update_buffers(struct iio_dev *indio_dev,
 911                        struct iio_buffer *insert_buffer,
 912                        struct iio_buffer *remove_buffer)
 913 {
 914         int ret;
 915
 916         if (insert_buffer == remove_buffer)
 917                 return 0;
 918
 919         mutex_lock(&indio_dev->info_exist_lock);
 920         mutex_lock(&indio_dev->mlock);
 921
 922         if (insert_buffer && iio_buffer_is_active(insert_buffer))
 923                 insert_buffer = NULL;
 924
 925         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
 926                 remove_buffer = NULL;
 927
 928         if (!insert_buffer && !remove_buffer) {
 929                 ret = 0;
 930                 goto out_unlock;
 931         }
 932
 933         if (indio_dev->info == NULL) {
 934                 ret = -ENODEV;
 935                 goto out_unlock;
 936         }
 937
 938         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 939
 940 out_unlock:
 941         mutex_unlock(&indio_dev->mlock);
 942         mutex_unlock(&indio_dev->info_exist_lock);
 943
 944         return ret;
 945 }
 946 EXPORT_SYMBOL_GPL(iio_update_buffers);
 947
 948 void iio_disable_all_buffers(struct iio_dev *indio_dev)
 949 {
 950         iio_disable_buffers(indio_dev);
 951         iio_buffer_deactivate_all(indio_dev);
 952 }
 953
 954 static ssize_t iio_buffer_store_enable(struct device *dev,
 955                                        struct device_attribute *attr,
 956                                        const char *buf,
 957                                        size_t len)
 958 {
 959         int ret;
 960         bool requested_state;
 961         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 962         bool inlist;
 963
 964         ret = strtobool(buf, &requested_state);
 965         if (ret < 0)
 966                 return ret;
 967
 968         mutex_lock(&indio_dev->mlock);
 969
 970         /* Find out if it is in the list */
 971         inlist = iio_buffer_is_active(indio_dev->buffer);
 972         /* Already in desired state */
 973         if (inlist == requested_state)
 974                 goto done;
 975
 976         if (requested_state)
 977                 ret = __iio_update_buffers(indio_dev,
 978                                          indio_dev->buffer, NULL);
 979         else
 980                 ret = __iio_update_buffers(indio_dev,
 981                                          NULL, indio_dev->buffer);
 982
 983 done:
 984         mutex_unlock(&indio_dev->mlock);
 985         return (ret < 0) ? ret : len;
 986 }
 987
 988 static const char * const iio_scan_elements_group_name = "scan_elements";
 989
 990 static ssize_t iio_buffer_show_watermark(struct device *dev,
 991                                          struct device_attribute *attr,
 992                                          char *buf)
 993 {
 994         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 995         struct iio_buffer *buffer = indio_dev->buffer;
 996
 997         return sprintf(buf, "%u\n", buffer->watermark);
 998 }
 999
1000 static ssize_t iio_buffer_store_watermark(struct device *dev,
1001                                           struct device_attribute *attr,
1002                                           const char *buf,
1003                                           size_t len)
1004 {
1005         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1006         struct iio_buffer *buffer = indio_dev->buffer;
1007         unsigned int val;
1008         int ret;
1009
1010         ret = kstrtouint(buf, 10, &val);
1011         if (ret)
1012                 return ret;
1013         if (!val)
1014                 return -EINVAL;
1015
1016         mutex_lock(&indio_dev->mlock);
1017
1018         if (val > buffer->length) {
1019                 ret = -EINVAL;
1020                 goto out;
1021         }
1022
1023         if (iio_buffer_is_active(indio_dev->buffer)) {
1024                 ret = -EBUSY;
1025                 goto out;
1026         }
1027
1028         buffer->watermark = val;
1029 out:
1030         mutex_unlock(&indio_dev->mlock);
1031
1032         return ret ? ret : len;
1033 }
1034
1035 static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
1036                    iio_buffer_write_length);
1037 static struct device_attribute dev_attr_length_ro = __ATTR(length,
1038         S_IRUGO, iio_buffer_read_length, NULL);
1039 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
1040                    iio_buffer_show_enable, iio_buffer_store_enable);
1041 static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
1042                    iio_buffer_show_watermark, iio_buffer_store_watermark);
1043 static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
1044         S_IRUGO, iio_buffer_show_watermark, NULL);
1045
1046 static struct attribute *iio_buffer_attrs[] = {
1047         &dev_attr_length.attr,
1048         &dev_attr_enable.attr,
1049         &dev_attr_watermark.attr,
1050 };
1051
1052 int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
1053 {
1054         struct iio_dev_attr *p;
1055         struct attribute **attr;
1056         struct iio_buffer *buffer = indio_dev->buffer;
1057         int ret, i, attrn, attrcount, attrcount_orig = 0;
1058         const struct iio_chan_spec *channels;
1059
1060         channels = indio_dev->channels;
1061         if (channels) {
1062                 int ml = indio_dev->masklength;
1063
1064                 for (i = 0; i < indio_dev->num_channels; i++)
1065                         ml = max(ml, channels[i].scan_index + 1);
1066                 indio_dev->masklength = ml;
1067         }
1068
1069         if (!buffer)
1070                 return 0;
1071
1072         attrcount = 0;
1073         if (buffer->attrs) {
1074                 while (buffer->attrs[attrcount] != NULL)
1075                         attrcount++;
1076         }
1077
1078         attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
1079                        sizeof(struct attribute *), GFP_KERNEL);
1080         if (!attr)
1081                 return -ENOMEM;
1082
1083         memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1084         if (!buffer->access->set_length)
1085                 attr[0] = &dev_attr_length_ro.attr;
1086
1087         if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
1088                 attr[2] = &dev_attr_watermark_ro.attr;
1089
1090         if (buffer->attrs)
1091                 memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
1092                        sizeof(struct attribute *) * attrcount);
1093
1094         attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
1095
1096         buffer->buffer_group.name = "buffer";
1097         buffer->buffer_group.attrs = attr;
1098
1099         indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
1100
1101         if (buffer->scan_el_attrs != NULL) {
1102                 attr = buffer->scan_el_attrs->attrs;
1103                 while (*attr++ != NULL)
1104                         attrcount_orig++;
1105         }
1106         attrcount = attrcount_orig;
1107         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
1108         channels = indio_dev->channels;
1109         if (channels) {
1110                 /* new magic */
1111                 for (i = 0; i < indio_dev->num_channels; i++) {
1112                         if (channels[i].scan_index < 0)
1113                                 continue;
1114
1115                         ret = iio_buffer_add_channel_sysfs(indio_dev,
1116                                                          &channels[i]);
1117                         if (ret < 0)
1118                                 goto error_cleanup_dynamic;
1119                         attrcount += ret;
1120                         if (channels[i].type == IIO_TIMESTAMP)
1121                                 indio_dev->scan_index_timestamp =
1122                                         channels[i].scan_index;
1123                 }
1124                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
1125                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
1126                                                     sizeof(*buffer->scan_mask),
1127                                                     GFP_KERNEL);
1128                         if (buffer->scan_mask == NULL) {
1129                                 ret = -ENOMEM;
1130                                 goto error_cleanup_dynamic;
1131                         }
1132                 }
1133         }
1134
1135         buffer->scan_el_group.name = iio_scan_elements_group_name;
1136
1137         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
1138                                               sizeof(buffer->scan_el_group.attrs[0]),
1139                                               GFP_KERNEL);
1140         if (buffer->scan_el_group.attrs == NULL) {
1141                 ret = -ENOMEM;
1142                 goto error_free_scan_mask;
1143         }
1144         if (buffer->scan_el_attrs)
1145                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
1146                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
1147         attrn = attrcount_orig;
1148
1149         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
1150                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
1151         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
1152
1153         return 0;
1154
1155 error_free_scan_mask:
1156         kfree(buffer->scan_mask);
1157 error_cleanup_dynamic:
1158         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
1159         kfree(indio_dev->buffer->buffer_group.attrs);
1160
1161         return ret;
1162 }
1163
1164 void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
1165 {
1166         if (!indio_dev->buffer)
1167                 return;
1168
1169         kfree(indio_dev->buffer->scan_mask);
1170         kfree(indio_dev->buffer->buffer_group.attrs);
1171         kfree(indio_dev->buffer->scan_el_group.attrs);
1172         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
1173 }
1174
1175 /**
1176  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1177  * @indio_dev: the iio device
1178  * @mask: scan mask to be checked
1179  *
1180  * Return true if exactly one bit is set in the scan mask, false otherwise. It
1181  * can be used for devices where only one channel can be active for sampling at
1182  * a time.
1183  */
1184 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1185         const unsigned long *mask)
1186 {
1187         return bitmap_weight(mask, indio_dev->masklength) == 1;
1188 }
1189 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1190
1191 int iio_scan_mask_query(struct iio_dev *indio_dev,
1192                         struct iio_buffer *buffer, int bit)
1193 {
1194         if (bit > indio_dev->masklength)
1195                 return -EINVAL;
1196
1197         if (!buffer->scan_mask)
1198                 return 0;
1199
1200         /* Ensure return value is 0 or 1. */
1201         return !!test_bit(bit, buffer->scan_mask);
1202 };
1203 EXPORT_SYMBOL_GPL(iio_scan_mask_query);
1204
1205 /**
1206  * struct iio_demux_table - table describing demux memcpy ops
1207  * @from:       index to copy from
1208  * @to:         index to copy to
1209  * @length:     how many bytes to copy
1210  * @l:          list head used for management
1211  */
1212 struct iio_demux_table {
1213         unsigned from;
1214         unsigned to;
1215         unsigned length;
1216         struct list_head l;
1217 };
1218
1219 static const void *iio_demux(struct iio_buffer *buffer,
1220                                  const void *datain)
1221 {
1222         struct iio_demux_table *t;
1223
1224         if (list_empty(&buffer->demux_list))
1225                 return datain;
1226         list_for_each_entry(t, &buffer->demux_list, l)
1227                 memcpy(buffer->demux_bounce + t->to,
1228                        datain + t->from, t->length);
1229
1230         return buffer->demux_bounce;
1231 }
1232
1233 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1234 {
1235         const void *dataout = iio_demux(buffer, data);
1236         int ret;
1237
1238         ret = buffer->access->store_to(buffer, dataout);
1239         if (ret)
1240                 return ret;
1241
1242         /*
1243          * We can't just test for watermark to decide if we wake the poll queue
1244          * because read may request less samples than the watermark.
1245          */
1246         wake_up_interruptible_poll(&buffer->pollq, POLLIN | POLLRDNORM);
1247         return 0;
1248 }
1249
1250 static void iio_buffer_demux_free(struct iio_buffer *buffer)
1251 {
1252         struct iio_demux_table *p, *q;
1253         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
1254                 list_del(&p->l);
1255                 kfree(p);
1256         }
1257 }
1258
1259
1260 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1261 {
1262         int ret;
1263         struct iio_buffer *buf;
1264
1265         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
1266                 ret = iio_push_to_buffer(buf, data);
1267                 if (ret < 0)
1268                         return ret;
1269         }
1270
1271         return 0;
1272 }
1273 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1274
1275 static int iio_buffer_add_demux(struct iio_buffer *buffer,
1276         struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
1277         unsigned int length)
1278 {
1279
1280         if (*p && (*p)->from + (*p)->length == in_loc &&
1281                 (*p)->to + (*p)->length == out_loc) {
1282                 (*p)->length += length;
1283         } else {
1284                 *p = kmalloc(sizeof(**p), GFP_KERNEL);
1285                 if (*p == NULL)
1286                         return -ENOMEM;
1287                 (*p)->from = in_loc;
1288                 (*p)->to = out_loc;
1289                 (*p)->length = length;
1290                 list_add_tail(&(*p)->l, &buffer->demux_list);
1291         }
1292
1293         return 0;
1294 }
1295
1296 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
1297                                    struct iio_buffer *buffer)
1298 {
1299         int ret, in_ind = -1, out_ind, length;
1300         unsigned in_loc = 0, out_loc = 0;
1301         struct iio_demux_table *p = NULL;
1302
1303         /* Clear out any old demux */
1304         iio_buffer_demux_free(buffer);
1305         kfree(buffer->demux_bounce);
1306         buffer->demux_bounce = NULL;
1307
1308         /* First work out which scan mode we will actually have */
1309         if (bitmap_equal(indio_dev->active_scan_mask,
1310                          buffer->scan_mask,
1311                          indio_dev->masklength))
1312                 return 0;
1313
1314         /* Now we have the two masks, work from least sig and build up sizes */
1315         for_each_set_bit(out_ind,
1316                          buffer->scan_mask,
1317                          indio_dev->masklength) {
1318                 in_ind = find_next_bit(indio_dev->active_scan_mask,
1319                                        indio_dev->masklength,
1320                                        in_ind + 1);
1321                 while (in_ind != out_ind) {
1322                         in_ind = find_next_bit(indio_dev->active_scan_mask,
1323                                                indio_dev->masklength,
1324                                                in_ind + 1);
1325                         length = iio_storage_bytes_for_si(indio_dev, in_ind);
1326                         /* Make sure we are aligned */
1327                         in_loc = roundup(in_loc, length) + length;
1328                 }
1329                 length = iio_storage_bytes_for_si(indio_dev, in_ind);
1330                 out_loc = roundup(out_loc, length);
1331                 in_loc = roundup(in_loc, length);
1332                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
1333                 if (ret)
1334                         goto error_clear_mux_table;
1335                 out_loc += length;
1336                 in_loc += length;
1337         }
1338         /* Relies on scan_timestamp being last */
1339         if (buffer->scan_timestamp) {
1340                 length = iio_storage_bytes_for_timestamp(indio_dev);
1341                 out_loc = roundup(out_loc, length);
1342                 in_loc = roundup(in_loc, length);
1343                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
1344                 if (ret)
1345                         goto error_clear_mux_table;
1346                 out_loc += length;
1347                 in_loc += length;
1348         }
1349         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
1350         if (buffer->demux_bounce == NULL) {
1351                 ret = -ENOMEM;
1352                 goto error_clear_mux_table;
1353         }
1354         return 0;
1355
1356 error_clear_mux_table:
1357         iio_buffer_demux_free(buffer);
1358
1359         return ret;
1360 }
1361
1362 int iio_update_demux(struct iio_dev *indio_dev)
1363 {
1364         struct iio_buffer *buffer;
1365         int ret;
1366
1367         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1368                 ret = iio_buffer_update_demux(indio_dev, buffer);
1369                 if (ret < 0)
1370                         goto error_clear_mux_table;
1371         }
1372         return 0;
1373
1374 error_clear_mux_table:
1375         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
1376                 iio_buffer_demux_free(buffer);
1377
1378         return ret;
1379 }
1380 EXPORT_SYMBOL_GPL(iio_update_demux);
1381
1382 /**
1383  * iio_buffer_release() - Free a buffer's resources
1384  * @ref: Pointer to the kref embedded in the iio_buffer struct
1385  *
1386  * This function is called when the last reference to the buffer has been
1387  * dropped. It will typically free all resources allocated by the buffer. Do not
1388  * call this function manually, always use iio_buffer_put() when done using a
1389  * buffer.
1390  */
1391 static void iio_buffer_release(struct kref *ref)
1392 {
1393         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1394
1395         buffer->access->release(buffer);
1396 }
1397
1398 /**
1399  * iio_buffer_get() - Grab a reference to the buffer
1400  * @buffer: The buffer to grab a reference for, may be NULL
1401  *
1402  * Returns the pointer to the buffer that was passed into the function.
1403  */
1404 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1405 {
1406         if (buffer)
1407                 kref_get(&buffer->ref);
1408
1409         return buffer;
1410 }
1411 EXPORT_SYMBOL_GPL(iio_buffer_get);
1412
1413 /**
1414  * iio_buffer_put() - Release the reference to the buffer
1415  * @buffer: The buffer to release the reference for, may be NULL
1416  */
1417 void iio_buffer_put(struct iio_buffer *buffer)
1418 {
1419         if (buffer)
1420                 kref_put(&buffer->ref, iio_buffer_release);
1421 }
1422 EXPORT_SYMBOL_GPL(iio_buffer_put);