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/signal.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 #include <linux/iio/buffer_impl.h>
  30
  31 static const char * const iio_endian_prefix[] = {
  32         [IIO_BE] = "be",
  33         [IIO_LE] = "le",
  34 };
  35
  36 static bool iio_buffer_is_active(struct iio_buffer *buf)
  37 {
  38         return !list_empty(&buf->buffer_list);
  39 }
  40
  41 static size_t iio_buffer_data_available(struct iio_buffer *buf)
  42 {
  43         return buf->access->data_available(buf);
  44 }
  45
  46 static int iio_buffer_flush_hwfifo(struct iio_dev *indio_dev,
  47                                    struct iio_buffer *buf, size_t required)
  48 {
  49         if (!indio_dev->info->hwfifo_flush_to_buffer)
  50                 return -ENODEV;
  51
  52         return indio_dev->info->hwfifo_flush_to_buffer(indio_dev, required);
  53 }
  54
  55 static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
  56                              size_t to_wait, int to_flush)
  57 {
  58         size_t avail;
  59         int flushed = 0;
  60
  61         /* wakeup if the device was unregistered */
  62         if (!indio_dev->info)
  63                 return true;
  64
  65         /* drain the buffer if it was disabled */
  66         if (!iio_buffer_is_active(buf)) {
  67                 to_wait = min_t(size_t, to_wait, 1);
  68                 to_flush = 0;
  69         }
  70
  71         avail = iio_buffer_data_available(buf);
  72
  73         if (avail >= to_wait) {
  74                 /* force a flush for non-blocking reads */
  75                 if (!to_wait && avail < to_flush)
  76                         iio_buffer_flush_hwfifo(indio_dev, buf,
  77                                                 to_flush - avail);
  78                 return true;
  79         }
  80
  81         if (to_flush)
  82                 flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
  83                                                   to_wait - avail);
  84         if (flushed <= 0)
  85                 return false;
  86
  87         if (avail + flushed >= to_wait)
  88                 return true;
  89
  90         return false;
  91 }
  92
  93 /**
  94  * iio_buffer_read_first_n_outer() - chrdev read for buffer access
  95  * @filp:       File structure pointer for the char device
  96  * @buf:        Destination buffer for iio buffer read
  97  * @n:          First n bytes to read
  98  * @f_ps:       Long offset provided by the user as a seek position
  99  *
 100  * This function relies on all buffer implementations having an
 101  * iio_buffer as their first element.
 102  *
 103  * Return: negative values corresponding to error codes or ret != 0
 104  *         for ending the reading activity
 105  **/
 106 ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
 107                                       size_t n, loff_t *f_ps)
 108 {
 109         struct iio_dev *indio_dev = filp->private_data;
 110         struct iio_buffer *rb = indio_dev->buffer;
 111         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 112         size_t datum_size;
 113         size_t to_wait;
 114         int ret = 0;
 115
 116         if (!indio_dev->info)
 117                 return -ENODEV;
 118
 119         if (!rb || !rb->access->read_first_n)
 120                 return -EINVAL;
 121
 122         datum_size = rb->bytes_per_datum;
 123
 124         /*
 125          * If datum_size is 0 there will never be anything to read from the
 126          * buffer, so signal end of file now.
 127          */
 128         if (!datum_size)
 129                 return 0;
 130
 131         if (filp->f_flags & O_NONBLOCK)
 132                 to_wait = 0;
 133         else
 134                 to_wait = min_t(size_t, n / datum_size, rb->watermark);
 135
 136         add_wait_queue(&rb->pollq, &wait);
 137         do {
 138                 if (!indio_dev->info) {
 139                         ret = -ENODEV;
 140                         break;
 141                 }
 142
 143                 if (!iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size)) {
 144                         if (signal_pending(current)) {
 145                                 ret = -ERESTARTSYS;
 146                                 break;
 147                         }
 148
 149                         wait_woken(&wait, TASK_INTERRUPTIBLE,
 150                                    MAX_SCHEDULE_TIMEOUT);
 151                         continue;
 152                 }
 153
 154                 ret = rb->access->read_first_n(rb, n, buf);
 155                 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
 156                         ret = -EAGAIN;
 157         } while (ret == 0);
 158         remove_wait_queue(&rb->pollq, &wait);
 159
 160         return ret;
 161 }
 162
 163 /**
 164  * iio_buffer_poll() - poll the buffer to find out if it has data
 165  * @filp:       File structure pointer for device access
 166  * @wait:       Poll table structure pointer for which the driver adds
 167  *              a wait queue
 168  *
 169  * Return: (POLLIN | POLLRDNORM) if data is available for reading
 170  *         or 0 for other cases
 171  */
 172 unsigned int iio_buffer_poll(struct file *filp,
 173                              struct poll_table_struct *wait)
 174 {
 175         struct iio_dev *indio_dev = filp->private_data;
 176         struct iio_buffer *rb = indio_dev->buffer;
 177
 178         if (!indio_dev->info)
 179                 return 0;
 180
 181         poll_wait(filp, &rb->pollq, wait);
 182         if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0))
 183                 return POLLIN | POLLRDNORM;
 184         return 0;
 185 }
 186
 187 /**
 188  * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
 189  * @indio_dev: The IIO device
 190  *
 191  * Wakes up the event waitqueue used for poll(). Should usually
 192  * be called when the device is unregistered.
 193  */
 194 void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
 195 {
 196         if (!indio_dev->buffer)
 197                 return;
 198
 199         wake_up(&indio_dev->buffer->pollq);
 200 }
 201
 202 void iio_buffer_init(struct iio_buffer *buffer)
 203 {
 204         INIT_LIST_HEAD(&buffer->demux_list);
 205         INIT_LIST_HEAD(&buffer->buffer_list);
 206         init_waitqueue_head(&buffer->pollq);
 207         kref_init(&buffer->ref);
 208         if (!buffer->watermark)
 209                 buffer->watermark = 1;
 210 }
 211 EXPORT_SYMBOL(iio_buffer_init);
 212
 213 /**
 214  * iio_buffer_set_attrs - Set buffer specific attributes
 215  * @buffer: The buffer for which we are setting attributes
 216  * @attrs: Pointer to a null terminated list of pointers to attributes
 217  */
 218 void iio_buffer_set_attrs(struct iio_buffer *buffer,
 219                          const struct attribute **attrs)
 220 {
 221         buffer->attrs = attrs;
 222 }
 223 EXPORT_SYMBOL_GPL(iio_buffer_set_attrs);
 224
 225 static ssize_t iio_show_scan_index(struct device *dev,
 226                                    struct device_attribute *attr,
 227                                    char *buf)
 228 {
 229         return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
 230 }
 231
 232 static ssize_t iio_show_fixed_type(struct device *dev,
 233                                    struct device_attribute *attr,
 234                                    char *buf)
 235 {
 236         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 237         u8 type = this_attr->c->scan_type.endianness;
 238
 239         if (type == IIO_CPU) {
 240 #ifdef __LITTLE_ENDIAN
 241                 type = IIO_LE;
 242 #else
 243                 type = IIO_BE;
 244 #endif
 245         }
 246         if (this_attr->c->scan_type.repeat > 1)
 247                 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
 248                        iio_endian_prefix[type],
 249                        this_attr->c->scan_type.sign,
 250                        this_attr->c->scan_type.realbits,
 251                        this_attr->c->scan_type.storagebits,
 252                        this_attr->c->scan_type.repeat,
 253                        this_attr->c->scan_type.shift);
 254                 else
 255                         return sprintf(buf, "%s:%c%d/%d>>%u\n",
 256                        iio_endian_prefix[type],
 257                        this_attr->c->scan_type.sign,
 258                        this_attr->c->scan_type.realbits,
 259                        this_attr->c->scan_type.storagebits,
 260                        this_attr->c->scan_type.shift);
 261 }
 262
 263 static ssize_t iio_scan_el_show(struct device *dev,
 264                                 struct device_attribute *attr,
 265                                 char *buf)
 266 {
 267         int ret;
 268         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 269
 270         /* Ensure ret is 0 or 1. */
 271         ret = !!test_bit(to_iio_dev_attr(attr)->address,
 272                        indio_dev->buffer->scan_mask);
 273
 274         return sprintf(buf, "%d\n", ret);
 275 }
 276
 277 /* Note NULL used as error indicator as it doesn't make sense. */
 278 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
 279                                           unsigned int masklength,
 280                                           const unsigned long *mask,
 281                                           bool strict)
 282 {
 283         if (bitmap_empty(mask, masklength))
 284                 return NULL;
 285         while (*av_masks) {
 286                 if (strict) {
 287                         if (bitmap_equal(mask, av_masks, masklength))
 288                                 return av_masks;
 289                 } else {
 290                         if (bitmap_subset(mask, av_masks, masklength))
 291                                 return av_masks;
 292                 }
 293                 av_masks += BITS_TO_LONGS(masklength);
 294         }
 295         return NULL;
 296 }
 297
 298 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
 299         const unsigned long *mask)
 300 {
 301         if (!indio_dev->setup_ops->validate_scan_mask)
 302                 return true;
 303
 304         return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
 305 }
 306
 307 /**
 308  * iio_scan_mask_set() - set particular bit in the scan mask
 309  * @indio_dev: the iio device
 310  * @buffer: the buffer whose scan mask we are interested in
 311  * @bit: the bit to be set.
 312  *
 313  * Note that at this point we have no way of knowing what other
 314  * buffers might request, hence this code only verifies that the
 315  * individual buffers request is plausible.
 316  */
 317 static int iio_scan_mask_set(struct iio_dev *indio_dev,
 318                       struct iio_buffer *buffer, int bit)
 319 {
 320         const unsigned long *mask;
 321         unsigned long *trialmask;
 322
 323         trialmask = kmalloc_array(BITS_TO_LONGS(indio_dev->masklength),
 324                                   sizeof(*trialmask),
 325                                   GFP_KERNEL);
 326         if (trialmask == NULL)
 327                 return -ENOMEM;
 328         if (!indio_dev->masklength) {
 329                 WARN(1, "Trying to set scanmask prior to registering buffer\n");
 330                 goto err_invalid_mask;
 331         }
 332         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 333         set_bit(bit, trialmask);
 334
 335         if (!iio_validate_scan_mask(indio_dev, trialmask))
 336                 goto err_invalid_mask;
 337
 338         if (indio_dev->available_scan_masks) {
 339                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 340                                            indio_dev->masklength,
 341                                            trialmask, false);
 342                 if (!mask)
 343                         goto err_invalid_mask;
 344         }
 345         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 346
 347         kfree(trialmask);
 348
 349         return 0;
 350
 351 err_invalid_mask:
 352         kfree(trialmask);
 353         return -EINVAL;
 354 }
 355
 356 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 357 {
 358         clear_bit(bit, buffer->scan_mask);
 359         return 0;
 360 }
 361
 362 static int iio_scan_mask_query(struct iio_dev *indio_dev,
 363                                struct iio_buffer *buffer, int bit)
 364 {
 365         if (bit > indio_dev->masklength)
 366                 return -EINVAL;
 367
 368         if (!buffer->scan_mask)
 369                 return 0;
 370
 371         /* Ensure return value is 0 or 1. */
 372         return !!test_bit(bit, buffer->scan_mask);
 373 };
 374
 375 static ssize_t iio_scan_el_store(struct device *dev,
 376                                  struct device_attribute *attr,
 377                                  const char *buf,
 378                                  size_t len)
 379 {
 380         int ret;
 381         bool state;
 382         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 383         struct iio_buffer *buffer = indio_dev->buffer;
 384         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 385
 386         ret = strtobool(buf, &state);
 387         if (ret < 0)
 388                 return ret;
 389         mutex_lock(&indio_dev->mlock);
 390         if (iio_buffer_is_active(indio_dev->buffer)) {
 391                 ret = -EBUSY;
 392                 goto error_ret;
 393         }
 394         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 395         if (ret < 0)
 396                 goto error_ret;
 397         if (!state && ret) {
 398                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 399                 if (ret)
 400                         goto error_ret;
 401         } else if (state && !ret) {
 402                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 403                 if (ret)
 404                         goto error_ret;
 405         }
 406
 407 error_ret:
 408         mutex_unlock(&indio_dev->mlock);
 409
 410         return ret < 0 ? ret : len;
 411
 412 }
 413
 414 static ssize_t iio_scan_el_ts_show(struct device *dev,
 415                                    struct device_attribute *attr,
 416                                    char *buf)
 417 {
 418         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 419         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 420 }
 421
 422 static ssize_t iio_scan_el_ts_store(struct device *dev,
 423                                     struct device_attribute *attr,
 424                                     const char *buf,
 425                                     size_t len)
 426 {
 427         int ret;
 428         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 429         bool state;
 430
 431         ret = strtobool(buf, &state);
 432         if (ret < 0)
 433                 return ret;
 434
 435         mutex_lock(&indio_dev->mlock);
 436         if (iio_buffer_is_active(indio_dev->buffer)) {
 437                 ret = -EBUSY;
 438                 goto error_ret;
 439         }
 440         indio_dev->buffer->scan_timestamp = state;
 441 error_ret:
 442         mutex_unlock(&indio_dev->mlock);
 443
 444         return ret ? ret : len;
 445 }
 446
 447 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 448                                         const struct iio_chan_spec *chan)
 449 {
 450         int ret, attrcount = 0;
 451         struct iio_buffer *buffer = indio_dev->buffer;
 452
 453         ret = __iio_add_chan_devattr("index",
 454                                      chan,
 455                                      &iio_show_scan_index,
 456                                      NULL,
 457                                      0,
 458                                      IIO_SEPARATE,
 459                                      &indio_dev->dev,
 460                                      &buffer->scan_el_dev_attr_list);
 461         if (ret)
 462                 return ret;
 463         attrcount++;
 464         ret = __iio_add_chan_devattr("type",
 465                                      chan,
 466                                      &iio_show_fixed_type,
 467                                      NULL,
 468                                      0,
 469                                      0,
 470                                      &indio_dev->dev,
 471                                      &buffer->scan_el_dev_attr_list);
 472         if (ret)
 473                 return ret;
 474         attrcount++;
 475         if (chan->type != IIO_TIMESTAMP)
 476                 ret = __iio_add_chan_devattr("en",
 477                                              chan,
 478                                              &iio_scan_el_show,
 479                                              &iio_scan_el_store,
 480                                              chan->scan_index,
 481                                              0,
 482                                              &indio_dev->dev,
 483                                              &buffer->scan_el_dev_attr_list);
 484         else
 485                 ret = __iio_add_chan_devattr("en",
 486                                              chan,
 487                                              &iio_scan_el_ts_show,
 488                                              &iio_scan_el_ts_store,
 489                                              chan->scan_index,
 490                                              0,
 491                                              &indio_dev->dev,
 492                                              &buffer->scan_el_dev_attr_list);
 493         if (ret)
 494                 return ret;
 495         attrcount++;
 496         ret = attrcount;
 497         return ret;
 498 }
 499
 500 static ssize_t iio_buffer_read_length(struct device *dev,
 501                                       struct device_attribute *attr,
 502                                       char *buf)
 503 {
 504         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 505         struct iio_buffer *buffer = indio_dev->buffer;
 506
 507         return sprintf(buf, "%d\n", buffer->length);
 508 }
 509
 510 static ssize_t iio_buffer_write_length(struct device *dev,
 511                                        struct device_attribute *attr,
 512                                        const char *buf, size_t len)
 513 {
 514         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 515         struct iio_buffer *buffer = indio_dev->buffer;
 516         unsigned int val;
 517         int ret;
 518
 519         ret = kstrtouint(buf, 10, &val);
 520         if (ret)
 521                 return ret;
 522
 523         if (val == buffer->length)
 524                 return len;
 525
 526         mutex_lock(&indio_dev->mlock);
 527         if (iio_buffer_is_active(indio_dev->buffer)) {
 528                 ret = -EBUSY;
 529         } else {
 530                 buffer->access->set_length(buffer, val);
 531                 ret = 0;
 532         }
 533         if (ret)
 534                 goto out;
 535         if (buffer->length && buffer->length < buffer->watermark)
 536                 buffer->watermark = buffer->length;
 537 out:
 538         mutex_unlock(&indio_dev->mlock);
 539
 540         return ret ? ret : len;
 541 }
 542
 543 static ssize_t iio_buffer_show_enable(struct device *dev,
 544                                       struct device_attribute *attr,
 545                                       char *buf)
 546 {
 547         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 548         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 549 }
 550
 551 static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
 552                                              unsigned int scan_index)
 553 {
 554         const struct iio_chan_spec *ch;
 555         unsigned int bytes;
 556
 557         ch = iio_find_channel_from_si(indio_dev, scan_index);
 558         bytes = ch->scan_type.storagebits / 8;
 559         if (ch->scan_type.repeat > 1)
 560                 bytes *= ch->scan_type.repeat;
 561         return bytes;
 562 }
 563
 564 static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
 565 {
 566         return iio_storage_bytes_for_si(indio_dev,
 567                                         indio_dev->scan_index_timestamp);
 568 }
 569
 570 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 571                                 const unsigned long *mask, bool timestamp)
 572 {
 573         unsigned bytes = 0;
 574         int length, i;
 575
 576         /* How much space will the demuxed element take? */
 577         for_each_set_bit(i, mask,
 578                          indio_dev->masklength) {
 579                 length = iio_storage_bytes_for_si(indio_dev, i);
 580                 bytes = ALIGN(bytes, length);
 581                 bytes += length;
 582         }
 583
 584         if (timestamp) {
 585                 length = iio_storage_bytes_for_timestamp(indio_dev);
 586                 bytes = ALIGN(bytes, length);
 587                 bytes += length;
 588         }
 589         return bytes;
 590 }
 591
 592 static void iio_buffer_activate(struct iio_dev *indio_dev,
 593         struct iio_buffer *buffer)
 594 {
 595         iio_buffer_get(buffer);
 596         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 597 }
 598
 599 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 600 {
 601         list_del_init(&buffer->buffer_list);
 602         wake_up_interruptible(&buffer->pollq);
 603         iio_buffer_put(buffer);
 604 }
 605
 606 static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
 607 {
 608         struct iio_buffer *buffer, *_buffer;
 609
 610         list_for_each_entry_safe(buffer, _buffer,
 611                         &indio_dev->buffer_list, buffer_list)
 612                 iio_buffer_deactivate(buffer);
 613 }
 614
 615 static int iio_buffer_enable(struct iio_buffer *buffer,
 616         struct iio_dev *indio_dev)
 617 {
 618         if (!buffer->access->enable)
 619                 return 0;
 620         return buffer->access->enable(buffer, indio_dev);
 621 }
 622
 623 static int iio_buffer_disable(struct iio_buffer *buffer,
 624         struct iio_dev *indio_dev)
 625 {
 626         if (!buffer->access->disable)
 627                 return 0;
 628         return buffer->access->disable(buffer, indio_dev);
 629 }
 630
 631 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 632         struct iio_buffer *buffer)
 633 {
 634         unsigned int bytes;
 635
 636         if (!buffer->access->set_bytes_per_datum)
 637                 return;
 638
 639         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 640                 buffer->scan_timestamp);
 641
 642         buffer->access->set_bytes_per_datum(buffer, bytes);
 643 }
 644
 645 static int iio_buffer_request_update(struct iio_dev *indio_dev,
 646         struct iio_buffer *buffer)
 647 {
 648         int ret;
 649
 650         iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 651         if (buffer->access->request_update) {
 652                 ret = buffer->access->request_update(buffer);
 653                 if (ret) {
 654                         dev_dbg(&indio_dev->dev,
 655                                "Buffer not started: buffer parameter update failed (%d)\n",
 656                                 ret);
 657                         return ret;
 658                 }
 659         }
 660
 661         return 0;
 662 }
 663
 664 static void iio_free_scan_mask(struct iio_dev *indio_dev,
 665         const unsigned long *mask)
 666 {
 667         /* If the mask is dynamically allocated free it, otherwise do nothing */
 668         if (!indio_dev->available_scan_masks)
 669                 kfree(mask);
 670 }
 671
 672 struct iio_device_config {
 673         unsigned int mode;
 674         unsigned int watermark;
 675         const unsigned long *scan_mask;
 676         unsigned int scan_bytes;
 677         bool scan_timestamp;
 678 };
 679
 680 static int iio_verify_update(struct iio_dev *indio_dev,
 681         struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
 682         struct iio_device_config *config)
 683 {
 684         unsigned long *compound_mask;
 685         const unsigned long *scan_mask;
 686         bool strict_scanmask = false;
 687         struct iio_buffer *buffer;
 688         bool scan_timestamp;
 689         unsigned int modes;
 690
 691         memset(config, 0, sizeof(*config));
 692         config->watermark = ~0;
 693
 694         /*
 695          * If there is just one buffer and we are removing it there is nothing
 696          * to verify.
 697          */
 698         if (remove_buffer && !insert_buffer &&
 699                 list_is_singular(&indio_dev->buffer_list))
 700                         return 0;
 701
 702         modes = indio_dev->modes;
 703
 704         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 705                 if (buffer == remove_buffer)
 706                         continue;
 707                 modes &= buffer->access->modes;
 708                 config->watermark = min(config->watermark, buffer->watermark);
 709         }
 710
 711         if (insert_buffer) {
 712                 modes &= insert_buffer->access->modes;
 713                 config->watermark = min(config->watermark,
 714                         insert_buffer->watermark);
 715         }
 716
 717         /* Definitely possible for devices to support both of these. */
 718         if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
 719                 config->mode = INDIO_BUFFER_TRIGGERED;
 720         } else if (modes & INDIO_BUFFER_HARDWARE) {
 721                 /*
 722                  * Keep things simple for now and only allow a single buffer to
 723                  * be connected in hardware mode.
 724                  */
 725                 if (insert_buffer && !list_empty(&indio_dev->buffer_list))
 726                         return -EINVAL;
 727                 config->mode = INDIO_BUFFER_HARDWARE;
 728                 strict_scanmask = true;
 729         } else if (modes & INDIO_BUFFER_SOFTWARE) {
 730                 config->mode = INDIO_BUFFER_SOFTWARE;
 731         } else {
 732                 /* Can only occur on first buffer */
 733                 if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
 734                         dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
 735                 return -EINVAL;
 736         }
 737
 738         /* What scan mask do we actually have? */
 739         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 740                                 sizeof(long), GFP_KERNEL);
 741         if (compound_mask == NULL)
 742                 return -ENOMEM;
 743
 744         scan_timestamp = false;
 745
 746         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 747                 if (buffer == remove_buffer)
 748                         continue;
 749                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 750                           indio_dev->masklength);
 751                 scan_timestamp |= buffer->scan_timestamp;
 752         }
 753
 754         if (insert_buffer) {
 755                 bitmap_or(compound_mask, compound_mask,
 756                           insert_buffer->scan_mask, indio_dev->masklength);
 757                 scan_timestamp |= insert_buffer->scan_timestamp;
 758         }
 759
 760         if (indio_dev->available_scan_masks) {
 761                 scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 762                                     indio_dev->masklength,
 763                                     compound_mask,
 764                                     strict_scanmask);
 765                 kfree(compound_mask);
 766                 if (scan_mask == NULL)
 767                         return -EINVAL;
 768         } else {
 769             scan_mask = compound_mask;
 770         }
 771
 772         config->scan_bytes = iio_compute_scan_bytes(indio_dev,
 773                                     scan_mask, scan_timestamp);
 774         config->scan_mask = scan_mask;
 775         config->scan_timestamp = scan_timestamp;
 776
 777         return 0;
 778 }
 779
 780 /**
 781  * struct iio_demux_table - table describing demux memcpy ops
 782  * @from:       index to copy from
 783  * @to:         index to copy to
 784  * @length:     how many bytes to copy
 785  * @l:          list head used for management
 786  */
 787 struct iio_demux_table {
 788         unsigned from;
 789         unsigned to;
 790         unsigned length;
 791         struct list_head l;
 792 };
 793
 794 static void iio_buffer_demux_free(struct iio_buffer *buffer)
 795 {
 796         struct iio_demux_table *p, *q;
 797         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
 798                 list_del(&p->l);
 799                 kfree(p);
 800         }
 801 }
 802
 803 static int iio_buffer_add_demux(struct iio_buffer *buffer,
 804         struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
 805         unsigned int length)
 806 {
 807
 808         if (*p && (*p)->from + (*p)->length == in_loc &&
 809                 (*p)->to + (*p)->length == out_loc) {
 810                 (*p)->length += length;
 811         } else {
 812                 *p = kmalloc(sizeof(**p), GFP_KERNEL);
 813                 if (*p == NULL)
 814                         return -ENOMEM;
 815                 (*p)->from = in_loc;
 816                 (*p)->to = out_loc;
 817                 (*p)->length = length;
 818                 list_add_tail(&(*p)->l, &buffer->demux_list);
 819         }
 820
 821         return 0;
 822 }
 823
 824 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
 825                                    struct iio_buffer *buffer)
 826 {
 827         int ret, in_ind = -1, out_ind, length;
 828         unsigned in_loc = 0, out_loc = 0;
 829         struct iio_demux_table *p = NULL;
 830
 831         /* Clear out any old demux */
 832         iio_buffer_demux_free(buffer);
 833         kfree(buffer->demux_bounce);
 834         buffer->demux_bounce = NULL;
 835
 836         /* First work out which scan mode we will actually have */
 837         if (bitmap_equal(indio_dev->active_scan_mask,
 838                          buffer->scan_mask,
 839                          indio_dev->masklength))
 840                 return 0;
 841
 842         /* Now we have the two masks, work from least sig and build up sizes */
 843         for_each_set_bit(out_ind,
 844                          buffer->scan_mask,
 845                          indio_dev->masklength) {
 846                 in_ind = find_next_bit(indio_dev->active_scan_mask,
 847                                        indio_dev->masklength,
 848                                        in_ind + 1);
 849                 while (in_ind != out_ind) {
 850                         in_ind = find_next_bit(indio_dev->active_scan_mask,
 851                                                indio_dev->masklength,
 852                                                in_ind + 1);
 853                         length = iio_storage_bytes_for_si(indio_dev, in_ind);
 854                         /* Make sure we are aligned */
 855                         in_loc = roundup(in_loc, length) + length;
 856                 }
 857                 length = iio_storage_bytes_for_si(indio_dev, in_ind);
 858                 out_loc = roundup(out_loc, length);
 859                 in_loc = roundup(in_loc, length);
 860                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
 861                 if (ret)
 862                         goto error_clear_mux_table;
 863                 out_loc += length;
 864                 in_loc += length;
 865         }
 866         /* Relies on scan_timestamp being last */
 867         if (buffer->scan_timestamp) {
 868                 length = iio_storage_bytes_for_timestamp(indio_dev);
 869                 out_loc = roundup(out_loc, length);
 870                 in_loc = roundup(in_loc, length);
 871                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
 872                 if (ret)
 873                         goto error_clear_mux_table;
 874                 out_loc += length;
 875                 in_loc += length;
 876         }
 877         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
 878         if (buffer->demux_bounce == NULL) {
 879                 ret = -ENOMEM;
 880                 goto error_clear_mux_table;
 881         }
 882         return 0;
 883
 884 error_clear_mux_table:
 885         iio_buffer_demux_free(buffer);
 886
 887         return ret;
 888 }
 889
 890 static int iio_update_demux(struct iio_dev *indio_dev)
 891 {
 892         struct iio_buffer *buffer;
 893         int ret;
 894
 895         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 896                 ret = iio_buffer_update_demux(indio_dev, buffer);
 897                 if (ret < 0)
 898                         goto error_clear_mux_table;
 899         }
 900         return 0;
 901
 902 error_clear_mux_table:
 903         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
 904                 iio_buffer_demux_free(buffer);
 905
 906         return ret;
 907 }
 908
 909 static int iio_enable_buffers(struct iio_dev *indio_dev,
 910         struct iio_device_config *config)
 911 {
 912         struct iio_buffer *buffer;
 913         int ret;
 914
 915         indio_dev->active_scan_mask = config->scan_mask;
 916         indio_dev->scan_timestamp = config->scan_timestamp;
 917         indio_dev->scan_bytes = config->scan_bytes;
 918
 919         iio_update_demux(indio_dev);
 920
 921         /* Wind up again */
 922         if (indio_dev->setup_ops->preenable) {
 923                 ret = indio_dev->setup_ops->preenable(indio_dev);
 924                 if (ret) {
 925                         dev_dbg(&indio_dev->dev,
 926                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 927                         goto err_undo_config;
 928                 }
 929         }
 930
 931         if (indio_dev->info->update_scan_mode) {
 932                 ret = indio_dev->info
 933                         ->update_scan_mode(indio_dev,
 934                                            indio_dev->active_scan_mask);
 935                 if (ret < 0) {
 936                         dev_dbg(&indio_dev->dev,
 937                                 "Buffer not started: update scan mode failed (%d)\n",
 938                                 ret);
 939                         goto err_run_postdisable;
 940                 }
 941         }
 942
 943         if (indio_dev->info->hwfifo_set_watermark)
 944                 indio_dev->info->hwfifo_set_watermark(indio_dev,
 945                         config->watermark);
 946
 947         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 948                 ret = iio_buffer_enable(buffer, indio_dev);
 949                 if (ret)
 950                         goto err_disable_buffers;
 951         }
 952
 953         indio_dev->currentmode = config->mode;
 954
 955         if (indio_dev->setup_ops->postenable) {
 956                 ret = indio_dev->setup_ops->postenable(indio_dev);
 957                 if (ret) {
 958                         dev_dbg(&indio_dev->dev,
 959                                "Buffer not started: postenable failed (%d)\n", ret);
 960                         goto err_disable_buffers;
 961                 }
 962         }
 963
 964         return 0;
 965
 966 err_disable_buffers:
 967         list_for_each_entry_continue_reverse(buffer, &indio_dev->buffer_list,
 968                                              buffer_list)
 969                 iio_buffer_disable(buffer, indio_dev);
 970 err_run_postdisable:
 971         indio_dev->currentmode = INDIO_DIRECT_MODE;
 972         if (indio_dev->setup_ops->postdisable)
 973                 indio_dev->setup_ops->postdisable(indio_dev);
 974 err_undo_config:
 975         indio_dev->active_scan_mask = NULL;
 976
 977         return ret;
 978 }
 979
 980 static int iio_disable_buffers(struct iio_dev *indio_dev)
 981 {
 982         struct iio_buffer *buffer;
 983         int ret = 0;
 984         int ret2;
 985
 986         /* Wind down existing buffers - iff there are any */
 987         if (list_empty(&indio_dev->buffer_list))
 988                 return 0;
 989
 990         /*
 991          * If things go wrong at some step in disable we still need to continue
 992          * to perform the other steps, otherwise we leave the device in a
 993          * inconsistent state. We return the error code for the first error we
 994          * encountered.
 995          */
 996
 997         if (indio_dev->setup_ops->predisable) {
 998                 ret2 = indio_dev->setup_ops->predisable(indio_dev);
 999                 if (ret2 && !ret)
1000                         ret = ret2;
1001         }
1002
1003         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1004                 ret2 = iio_buffer_disable(buffer, indio_dev);
1005                 if (ret2 && !ret)
1006                         ret = ret2;
1007         }
1008
1009         indio_dev->currentmode = INDIO_DIRECT_MODE;
1010
1011         if (indio_dev->setup_ops->postdisable) {
1012                 ret2 = indio_dev->setup_ops->postdisable(indio_dev);
1013                 if (ret2 && !ret)
1014                         ret = ret2;
1015         }
1016
1017         iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
1018         indio_dev->active_scan_mask = NULL;
1019
1020         return ret;
1021 }
1022
1023 static int __iio_update_buffers(struct iio_dev *indio_dev,
1024                        struct iio_buffer *insert_buffer,
1025                        struct iio_buffer *remove_buffer)
1026 {
1027         struct iio_device_config new_config;
1028         int ret;
1029
1030         ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
1031                 &new_config);
1032         if (ret)
1033                 return ret;
1034
1035         if (insert_buffer) {
1036                 ret = iio_buffer_request_update(indio_dev, insert_buffer);
1037                 if (ret)
1038                         goto err_free_config;
1039         }
1040
1041         ret = iio_disable_buffers(indio_dev);
1042         if (ret)
1043                 goto err_deactivate_all;
1044
1045         if (remove_buffer)
1046                 iio_buffer_deactivate(remove_buffer);
1047         if (insert_buffer)
1048                 iio_buffer_activate(indio_dev, insert_buffer);
1049
1050         /* If no buffers in list, we are done */
1051         if (list_empty(&indio_dev->buffer_list))
1052                 return 0;
1053
1054         ret = iio_enable_buffers(indio_dev, &new_config);
1055         if (ret)
1056                 goto err_deactivate_all;
1057
1058         return 0;
1059
1060 err_deactivate_all:
1061         /*
1062          * We've already verified that the config is valid earlier. If things go
1063          * wrong in either enable or disable the most likely reason is an IO
1064          * error from the device. In this case there is no good recovery
1065          * strategy. Just make sure to disable everything and leave the device
1066          * in a sane state.  With a bit of luck the device might come back to
1067          * life again later and userspace can try again.
1068          */
1069         iio_buffer_deactivate_all(indio_dev);
1070
1071 err_free_config:
1072         iio_free_scan_mask(indio_dev, new_config.scan_mask);
1073         return ret;
1074 }
1075
1076 int iio_update_buffers(struct iio_dev *indio_dev,
1077                        struct iio_buffer *insert_buffer,
1078                        struct iio_buffer *remove_buffer)
1079 {
1080         int ret;
1081
1082         if (insert_buffer == remove_buffer)
1083                 return 0;
1084
1085         mutex_lock(&indio_dev->info_exist_lock);
1086         mutex_lock(&indio_dev->mlock);
1087
1088         if (insert_buffer && iio_buffer_is_active(insert_buffer))
1089                 insert_buffer = NULL;
1090
1091         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
1092                 remove_buffer = NULL;
1093
1094         if (!insert_buffer && !remove_buffer) {
1095                 ret = 0;
1096                 goto out_unlock;
1097         }
1098
1099         if (indio_dev->info == NULL) {
1100                 ret = -ENODEV;
1101                 goto out_unlock;
1102         }
1103
1104         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
1105
1106 out_unlock:
1107         mutex_unlock(&indio_dev->mlock);
1108         mutex_unlock(&indio_dev->info_exist_lock);
1109
1110         return ret;
1111 }
1112 EXPORT_SYMBOL_GPL(iio_update_buffers);
1113
1114 void iio_disable_all_buffers(struct iio_dev *indio_dev)
1115 {
1116         iio_disable_buffers(indio_dev);
1117         iio_buffer_deactivate_all(indio_dev);
1118 }
1119
1120 static ssize_t iio_buffer_store_enable(struct device *dev,
1121                                        struct device_attribute *attr,
1122                                        const char *buf,
1123                                        size_t len)
1124 {
1125         int ret;
1126         bool requested_state;
1127         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1128         bool inlist;
1129
1130         ret = strtobool(buf, &requested_state);
1131         if (ret < 0)
1132                 return ret;
1133
1134         mutex_lock(&indio_dev->mlock);
1135
1136         /* Find out if it is in the list */
1137         inlist = iio_buffer_is_active(indio_dev->buffer);
1138         /* Already in desired state */
1139         if (inlist == requested_state)
1140                 goto done;
1141
1142         if (requested_state)
1143                 ret = __iio_update_buffers(indio_dev,
1144                                          indio_dev->buffer, NULL);
1145         else
1146                 ret = __iio_update_buffers(indio_dev,
1147                                          NULL, indio_dev->buffer);
1148
1149 done:
1150         mutex_unlock(&indio_dev->mlock);
1151         return (ret < 0) ? ret : len;
1152 }
1153
1154 static const char * const iio_scan_elements_group_name = "scan_elements";
1155
1156 static ssize_t iio_buffer_show_watermark(struct device *dev,
1157                                          struct device_attribute *attr,
1158                                          char *buf)
1159 {
1160         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1161         struct iio_buffer *buffer = indio_dev->buffer;
1162
1163         return sprintf(buf, "%u\n", buffer->watermark);
1164 }
1165
1166 static ssize_t iio_buffer_store_watermark(struct device *dev,
1167                                           struct device_attribute *attr,
1168                                           const char *buf,
1169                                           size_t len)
1170 {
1171         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1172         struct iio_buffer *buffer = indio_dev->buffer;
1173         unsigned int val;
1174         int ret;
1175
1176         ret = kstrtouint(buf, 10, &val);
1177         if (ret)
1178                 return ret;
1179         if (!val)
1180                 return -EINVAL;
1181
1182         mutex_lock(&indio_dev->mlock);
1183
1184         if (val > buffer->length) {
1185                 ret = -EINVAL;
1186                 goto out;
1187         }
1188
1189         if (iio_buffer_is_active(indio_dev->buffer)) {
1190                 ret = -EBUSY;
1191                 goto out;
1192         }
1193
1194         buffer->watermark = val;
1195 out:
1196         mutex_unlock(&indio_dev->mlock);
1197
1198         return ret ? ret : len;
1199 }
1200
1201 static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
1202                    iio_buffer_write_length);
1203 static struct device_attribute dev_attr_length_ro = __ATTR(length,
1204         S_IRUGO, iio_buffer_read_length, NULL);
1205 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
1206                    iio_buffer_show_enable, iio_buffer_store_enable);
1207 static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
1208                    iio_buffer_show_watermark, iio_buffer_store_watermark);
1209 static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
1210         S_IRUGO, iio_buffer_show_watermark, NULL);
1211
1212 static struct attribute *iio_buffer_attrs[] = {
1213         &dev_attr_length.attr,
1214         &dev_attr_enable.attr,
1215         &dev_attr_watermark.attr,
1216 };
1217
1218 int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
1219 {
1220         struct iio_dev_attr *p;
1221         struct attribute **attr;
1222         struct iio_buffer *buffer = indio_dev->buffer;
1223         int ret, i, attrn, attrcount, attrcount_orig = 0;
1224         const struct iio_chan_spec *channels;
1225
1226         channels = indio_dev->channels;
1227         if (channels) {
1228                 int ml = indio_dev->masklength;
1229
1230                 for (i = 0; i < indio_dev->num_channels; i++)
1231                         ml = max(ml, channels[i].scan_index + 1);
1232                 indio_dev->masklength = ml;
1233         }
1234
1235         if (!buffer)
1236                 return 0;
1237
1238         attrcount = 0;
1239         if (buffer->attrs) {
1240                 while (buffer->attrs[attrcount] != NULL)
1241                         attrcount++;
1242         }
1243
1244         attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
1245                        sizeof(struct attribute *), GFP_KERNEL);
1246         if (!attr)
1247                 return -ENOMEM;
1248
1249         memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1250         if (!buffer->access->set_length)
1251                 attr[0] = &dev_attr_length_ro.attr;
1252
1253         if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
1254                 attr[2] = &dev_attr_watermark_ro.attr;
1255
1256         if (buffer->attrs)
1257                 memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
1258                        sizeof(struct attribute *) * attrcount);
1259
1260         attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
1261
1262         buffer->buffer_group.name = "buffer";
1263         buffer->buffer_group.attrs = attr;
1264
1265         indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
1266
1267         if (buffer->scan_el_attrs != NULL) {
1268                 attr = buffer->scan_el_attrs->attrs;
1269                 while (*attr++ != NULL)
1270                         attrcount_orig++;
1271         }
1272         attrcount = attrcount_orig;
1273         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
1274         channels = indio_dev->channels;
1275         if (channels) {
1276                 /* new magic */
1277                 for (i = 0; i < indio_dev->num_channels; i++) {
1278                         if (channels[i].scan_index < 0)
1279                                 continue;
1280
1281                         ret = iio_buffer_add_channel_sysfs(indio_dev,
1282                                                          &channels[i]);
1283                         if (ret < 0)
1284                                 goto error_cleanup_dynamic;
1285                         attrcount += ret;
1286                         if (channels[i].type == IIO_TIMESTAMP)
1287                                 indio_dev->scan_index_timestamp =
1288                                         channels[i].scan_index;
1289                 }
1290                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
1291                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
1292                                                     sizeof(*buffer->scan_mask),
1293                                                     GFP_KERNEL);
1294                         if (buffer->scan_mask == NULL) {
1295                                 ret = -ENOMEM;
1296                                 goto error_cleanup_dynamic;
1297                         }
1298                 }
1299         }
1300
1301         buffer->scan_el_group.name = iio_scan_elements_group_name;
1302
1303         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
1304                                               sizeof(buffer->scan_el_group.attrs[0]),
1305                                               GFP_KERNEL);
1306         if (buffer->scan_el_group.attrs == NULL) {
1307                 ret = -ENOMEM;
1308                 goto error_free_scan_mask;
1309         }
1310         if (buffer->scan_el_attrs)
1311                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
1312                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
1313         attrn = attrcount_orig;
1314
1315         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
1316                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
1317         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
1318
1319         return 0;
1320
1321 error_free_scan_mask:
1322         kfree(buffer->scan_mask);
1323 error_cleanup_dynamic:
1324         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
1325         kfree(indio_dev->buffer->buffer_group.attrs);
1326
1327         return ret;
1328 }
1329
1330 void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
1331 {
1332         if (!indio_dev->buffer)
1333                 return;
1334
1335         kfree(indio_dev->buffer->scan_mask);
1336         kfree(indio_dev->buffer->buffer_group.attrs);
1337         kfree(indio_dev->buffer->scan_el_group.attrs);
1338         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
1339 }
1340
1341 /**
1342  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1343  * @indio_dev: the iio device
1344  * @mask: scan mask to be checked
1345  *
1346  * Return true if exactly one bit is set in the scan mask, false otherwise. It
1347  * can be used for devices where only one channel can be active for sampling at
1348  * a time.
1349  */
1350 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1351         const unsigned long *mask)
1352 {
1353         return bitmap_weight(mask, indio_dev->masklength) == 1;
1354 }
1355 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1356
1357 static const void *iio_demux(struct iio_buffer *buffer,
1358                                  const void *datain)
1359 {
1360         struct iio_demux_table *t;
1361
1362         if (list_empty(&buffer->demux_list))
1363                 return datain;
1364         list_for_each_entry(t, &buffer->demux_list, l)
1365                 memcpy(buffer->demux_bounce + t->to,
1366                        datain + t->from, t->length);
1367
1368         return buffer->demux_bounce;
1369 }
1370
1371 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1372 {
1373         const void *dataout = iio_demux(buffer, data);
1374         int ret;
1375
1376         ret = buffer->access->store_to(buffer, dataout);
1377         if (ret)
1378                 return ret;
1379
1380         /*
1381          * We can't just test for watermark to decide if we wake the poll queue
1382          * because read may request less samples than the watermark.
1383          */
1384         wake_up_interruptible_poll(&buffer->pollq, POLLIN | POLLRDNORM);
1385         return 0;
1386 }
1387
1388 /**
1389  * iio_push_to_buffers() - push to a registered buffer.
1390  * @indio_dev:          iio_dev structure for device.
1391  * @data:               Full scan.
1392  */
1393 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1394 {
1395         int ret;
1396         struct iio_buffer *buf;
1397
1398         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
1399                 ret = iio_push_to_buffer(buf, data);
1400                 if (ret < 0)
1401                         return ret;
1402         }
1403
1404         return 0;
1405 }
1406 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1407
1408 /**
1409  * iio_buffer_release() - Free a buffer's resources
1410  * @ref: Pointer to the kref embedded in the iio_buffer struct
1411  *
1412  * This function is called when the last reference to the buffer has been
1413  * dropped. It will typically free all resources allocated by the buffer. Do not
1414  * call this function manually, always use iio_buffer_put() when done using a
1415  * buffer.
1416  */
1417 static void iio_buffer_release(struct kref *ref)
1418 {
1419         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1420
1421         buffer->access->release(buffer);
1422 }
1423
1424 /**
1425  * iio_buffer_get() - Grab a reference to the buffer
1426  * @buffer: The buffer to grab a reference for, may be NULL
1427  *
1428  * Returns the pointer to the buffer that was passed into the function.
1429  */
1430 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1431 {
1432         if (buffer)
1433                 kref_get(&buffer->ref);
1434
1435         return buffer;
1436 }
1437 EXPORT_SYMBOL_GPL(iio_buffer_get);
1438
1439 /**
1440  * iio_buffer_put() - Release the reference to the buffer
1441  * @buffer: The buffer to release the reference for, may be NULL
1442  */
1443 void iio_buffer_put(struct iio_buffer *buffer)
1444 {
1445         if (buffer)
1446                 kref_put(&buffer->ref, iio_buffer_release);
1447 }
1448 EXPORT_SYMBOL_GPL(iio_buffer_put);
1449
1450 /**
1451  * iio_device_attach_buffer - Attach a buffer to a IIO device
1452  * @indio_dev: The device the buffer should be attached to
1453  * @buffer: The buffer to attach to the device
1454  *
1455  * This function attaches a buffer to a IIO device. The buffer stays attached to
1456  * the device until the device is freed. The function should only be called at
1457  * most once per device.
1458  */
1459 void iio_device_attach_buffer(struct iio_dev *indio_dev,
1460                               struct iio_buffer *buffer)
1461 {
1462         indio_dev->buffer = iio_buffer_get(buffer);
1463 }
1464 EXPORT_SYMBOL_GPL(iio_device_attach_buffer);