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 || rb == NULL)
 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 = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 324                             sizeof(*trialmask), GFP_KERNEL);
 325         if (trialmask == NULL)
 326                 return -ENOMEM;
 327         if (!indio_dev->masklength) {
 328                 WARN(1, "Trying to set scanmask prior to registering buffer\n");
 329                 goto err_invalid_mask;
 330         }
 331         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 332         set_bit(bit, trialmask);
 333
 334         if (!iio_validate_scan_mask(indio_dev, trialmask))
 335                 goto err_invalid_mask;
 336
 337         if (indio_dev->available_scan_masks) {
 338                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 339                                            indio_dev->masklength,
 340                                            trialmask, false);
 341                 if (!mask)
 342                         goto err_invalid_mask;
 343         }
 344         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 345
 346         kfree(trialmask);
 347
 348         return 0;
 349
 350 err_invalid_mask:
 351         kfree(trialmask);
 352         return -EINVAL;
 353 }
 354
 355 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 356 {
 357         clear_bit(bit, buffer->scan_mask);
 358         return 0;
 359 }
 360
 361 static int iio_scan_mask_query(struct iio_dev *indio_dev,
 362                                struct iio_buffer *buffer, int bit)
 363 {
 364         if (bit > indio_dev->masklength)
 365                 return -EINVAL;
 366
 367         if (!buffer->scan_mask)
 368                 return 0;
 369
 370         /* Ensure return value is 0 or 1. */
 371         return !!test_bit(bit, buffer->scan_mask);
 372 };
 373
 374 static ssize_t iio_scan_el_store(struct device *dev,
 375                                  struct device_attribute *attr,
 376                                  const char *buf,
 377                                  size_t len)
 378 {
 379         int ret;
 380         bool state;
 381         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 382         struct iio_buffer *buffer = indio_dev->buffer;
 383         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 384
 385         ret = strtobool(buf, &state);
 386         if (ret < 0)
 387                 return ret;
 388         mutex_lock(&indio_dev->mlock);
 389         if (iio_buffer_is_active(indio_dev->buffer)) {
 390                 ret = -EBUSY;
 391                 goto error_ret;
 392         }
 393         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 394         if (ret < 0)
 395                 goto error_ret;
 396         if (!state && ret) {
 397                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 398                 if (ret)
 399                         goto error_ret;
 400         } else if (state && !ret) {
 401                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 402                 if (ret)
 403                         goto error_ret;
 404         }
 405
 406 error_ret:
 407         mutex_unlock(&indio_dev->mlock);
 408
 409         return ret < 0 ? ret : len;
 410
 411 }
 412
 413 static ssize_t iio_scan_el_ts_show(struct device *dev,
 414                                    struct device_attribute *attr,
 415                                    char *buf)
 416 {
 417         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 418         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 419 }
 420
 421 static ssize_t iio_scan_el_ts_store(struct device *dev,
 422                                     struct device_attribute *attr,
 423                                     const char *buf,
 424                                     size_t len)
 425 {
 426         int ret;
 427         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 428         bool state;
 429
 430         ret = strtobool(buf, &state);
 431         if (ret < 0)
 432                 return ret;
 433
 434         mutex_lock(&indio_dev->mlock);
 435         if (iio_buffer_is_active(indio_dev->buffer)) {
 436                 ret = -EBUSY;
 437                 goto error_ret;
 438         }
 439         indio_dev->buffer->scan_timestamp = state;
 440 error_ret:
 441         mutex_unlock(&indio_dev->mlock);
 442
 443         return ret ? ret : len;
 444 }
 445
 446 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 447                                         const struct iio_chan_spec *chan)
 448 {
 449         int ret, attrcount = 0;
 450         struct iio_buffer *buffer = indio_dev->buffer;
 451
 452         ret = __iio_add_chan_devattr("index",
 453                                      chan,
 454                                      &iio_show_scan_index,
 455                                      NULL,
 456                                      0,
 457                                      IIO_SEPARATE,
 458                                      &indio_dev->dev,
 459                                      &buffer->scan_el_dev_attr_list);
 460         if (ret)
 461                 return ret;
 462         attrcount++;
 463         ret = __iio_add_chan_devattr("type",
 464                                      chan,
 465                                      &iio_show_fixed_type,
 466                                      NULL,
 467                                      0,
 468                                      0,
 469                                      &indio_dev->dev,
 470                                      &buffer->scan_el_dev_attr_list);
 471         if (ret)
 472                 return ret;
 473         attrcount++;
 474         if (chan->type != IIO_TIMESTAMP)
 475                 ret = __iio_add_chan_devattr("en",
 476                                              chan,
 477                                              &iio_scan_el_show,
 478                                              &iio_scan_el_store,
 479                                              chan->scan_index,
 480                                              0,
 481                                              &indio_dev->dev,
 482                                              &buffer->scan_el_dev_attr_list);
 483         else
 484                 ret = __iio_add_chan_devattr("en",
 485                                              chan,
 486                                              &iio_scan_el_ts_show,
 487                                              &iio_scan_el_ts_store,
 488                                              chan->scan_index,
 489                                              0,
 490                                              &indio_dev->dev,
 491                                              &buffer->scan_el_dev_attr_list);
 492         if (ret)
 493                 return ret;
 494         attrcount++;
 495         ret = attrcount;
 496         return ret;
 497 }
 498
 499 static ssize_t iio_buffer_read_length(struct device *dev,
 500                                       struct device_attribute *attr,
 501                                       char *buf)
 502 {
 503         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 504         struct iio_buffer *buffer = indio_dev->buffer;
 505
 506         return sprintf(buf, "%d\n", buffer->length);
 507 }
 508
 509 static ssize_t iio_buffer_write_length(struct device *dev,
 510                                        struct device_attribute *attr,
 511                                        const char *buf, size_t len)
 512 {
 513         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 514         struct iio_buffer *buffer = indio_dev->buffer;
 515         unsigned int val;
 516         int ret;
 517
 518         ret = kstrtouint(buf, 10, &val);
 519         if (ret)
 520                 return ret;
 521
 522         if (val == buffer->length)
 523                 return len;
 524
 525         mutex_lock(&indio_dev->mlock);
 526         if (iio_buffer_is_active(indio_dev->buffer)) {
 527                 ret = -EBUSY;
 528         } else {
 529                 buffer->access->set_length(buffer, val);
 530                 ret = 0;
 531         }
 532         if (ret)
 533                 goto out;
 534         if (buffer->length && buffer->length < buffer->watermark)
 535                 buffer->watermark = buffer->length;
 536 out:
 537         mutex_unlock(&indio_dev->mlock);
 538
 539         return ret ? ret : len;
 540 }
 541
 542 static ssize_t iio_buffer_show_enable(struct device *dev,
 543                                       struct device_attribute *attr,
 544                                       char *buf)
 545 {
 546         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 547         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 548 }
 549
 550 static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
 551                                              unsigned int scan_index)
 552 {
 553         const struct iio_chan_spec *ch;
 554         unsigned int bytes;
 555
 556         ch = iio_find_channel_from_si(indio_dev, scan_index);
 557         bytes = ch->scan_type.storagebits / 8;
 558         if (ch->scan_type.repeat > 1)
 559                 bytes *= ch->scan_type.repeat;
 560         return bytes;
 561 }
 562
 563 static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
 564 {
 565         return iio_storage_bytes_for_si(indio_dev,
 566                                         indio_dev->scan_index_timestamp);
 567 }
 568
 569 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 570                                 const unsigned long *mask, bool timestamp)
 571 {
 572         unsigned bytes = 0;
 573         int length, i, largest = 0;
 574
 575         /* How much space will the demuxed element take? */
 576         for_each_set_bit(i, mask,
 577                          indio_dev->masklength) {
 578                 length = iio_storage_bytes_for_si(indio_dev, i);
 579                 bytes = ALIGN(bytes, length);
 580                 bytes += length;
 581                 largest = max(largest, length);
 582         }
 583
 584         if (timestamp) {
 585                 length = iio_storage_bytes_for_timestamp(indio_dev);
 586                 bytes = ALIGN(bytes, length);
 587                 bytes += length;
 588                 largest = max(largest, length);
 589         }
 590
 591         bytes = ALIGN(bytes, largest);
 592         return bytes;
 593 }
 594
 595 static void iio_buffer_activate(struct iio_dev *indio_dev,
 596         struct iio_buffer *buffer)
 597 {
 598         iio_buffer_get(buffer);
 599         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 600 }
 601
 602 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 603 {
 604         list_del_init(&buffer->buffer_list);
 605         wake_up_interruptible(&buffer->pollq);
 606         iio_buffer_put(buffer);
 607 }
 608
 609 static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
 610 {
 611         struct iio_buffer *buffer, *_buffer;
 612
 613         list_for_each_entry_safe(buffer, _buffer,
 614                         &indio_dev->buffer_list, buffer_list)
 615                 iio_buffer_deactivate(buffer);
 616 }
 617
 618 static int iio_buffer_enable(struct iio_buffer *buffer,
 619         struct iio_dev *indio_dev)
 620 {
 621         if (!buffer->access->enable)
 622                 return 0;
 623         return buffer->access->enable(buffer, indio_dev);
 624 }
 625
 626 static int iio_buffer_disable(struct iio_buffer *buffer,
 627         struct iio_dev *indio_dev)
 628 {
 629         if (!buffer->access->disable)
 630                 return 0;
 631         return buffer->access->disable(buffer, indio_dev);
 632 }
 633
 634 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 635         struct iio_buffer *buffer)
 636 {
 637         unsigned int bytes;
 638
 639         if (!buffer->access->set_bytes_per_datum)
 640                 return;
 641
 642         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 643                 buffer->scan_timestamp);
 644
 645         buffer->access->set_bytes_per_datum(buffer, bytes);
 646 }
 647
 648 static int iio_buffer_request_update(struct iio_dev *indio_dev,
 649         struct iio_buffer *buffer)
 650 {
 651         int ret;
 652
 653         iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 654         if (buffer->access->request_update) {
 655                 ret = buffer->access->request_update(buffer);
 656                 if (ret) {
 657                         dev_dbg(&indio_dev->dev,
 658                                "Buffer not started: buffer parameter update failed (%d)\n",
 659                                 ret);
 660                         return ret;
 661                 }
 662         }
 663
 664         return 0;
 665 }
 666
 667 static void iio_free_scan_mask(struct iio_dev *indio_dev,
 668         const unsigned long *mask)
 669 {
 670         /* If the mask is dynamically allocated free it, otherwise do nothing */
 671         if (!indio_dev->available_scan_masks)
 672                 kfree(mask);
 673 }
 674
 675 struct iio_device_config {
 676         unsigned int mode;
 677         unsigned int watermark;
 678         const unsigned long *scan_mask;
 679         unsigned int scan_bytes;
 680         bool scan_timestamp;
 681 };
 682
 683 static int iio_verify_update(struct iio_dev *indio_dev,
 684         struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
 685         struct iio_device_config *config)
 686 {
 687         unsigned long *compound_mask;
 688         const unsigned long *scan_mask;
 689         bool strict_scanmask = false;
 690         struct iio_buffer *buffer;
 691         bool scan_timestamp;
 692         unsigned int modes;
 693
 694         memset(config, 0, sizeof(*config));
 695         config->watermark = ~0;
 696
 697         /*
 698          * If there is just one buffer and we are removing it there is nothing
 699          * to verify.
 700          */
 701         if (remove_buffer && !insert_buffer &&
 702                 list_is_singular(&indio_dev->buffer_list))
 703                         return 0;
 704
 705         modes = indio_dev->modes;
 706
 707         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 708                 if (buffer == remove_buffer)
 709                         continue;
 710                 modes &= buffer->access->modes;
 711                 config->watermark = min(config->watermark, buffer->watermark);
 712         }
 713
 714         if (insert_buffer) {
 715                 modes &= insert_buffer->access->modes;
 716                 config->watermark = min(config->watermark,
 717                         insert_buffer->watermark);
 718         }
 719
 720         /* Definitely possible for devices to support both of these. */
 721         if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
 722                 config->mode = INDIO_BUFFER_TRIGGERED;
 723         } else if (modes & INDIO_BUFFER_HARDWARE) {
 724                 /*
 725                  * Keep things simple for now and only allow a single buffer to
 726                  * be connected in hardware mode.
 727                  */
 728                 if (insert_buffer && !list_empty(&indio_dev->buffer_list))
 729                         return -EINVAL;
 730                 config->mode = INDIO_BUFFER_HARDWARE;
 731                 strict_scanmask = true;
 732         } else if (modes & INDIO_BUFFER_SOFTWARE) {
 733                 config->mode = INDIO_BUFFER_SOFTWARE;
 734         } else {
 735                 /* Can only occur on first buffer */
 736                 if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
 737                         dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
 738                 return -EINVAL;
 739         }
 740
 741         /* What scan mask do we actually have? */
 742         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 743                                 sizeof(long), GFP_KERNEL);
 744         if (compound_mask == NULL)
 745                 return -ENOMEM;
 746
 747         scan_timestamp = false;
 748
 749         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 750                 if (buffer == remove_buffer)
 751                         continue;
 752                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 753                           indio_dev->masklength);
 754                 scan_timestamp |= buffer->scan_timestamp;
 755         }
 756
 757         if (insert_buffer) {
 758                 bitmap_or(compound_mask, compound_mask,
 759                           insert_buffer->scan_mask, indio_dev->masklength);
 760                 scan_timestamp |= insert_buffer->scan_timestamp;
 761         }
 762
 763         if (indio_dev->available_scan_masks) {
 764                 scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 765                                     indio_dev->masklength,
 766                                     compound_mask,
 767                                     strict_scanmask);
 768                 kfree(compound_mask);
 769                 if (scan_mask == NULL)
 770                         return -EINVAL;
 771         } else {
 772             scan_mask = compound_mask;
 773         }
 774
 775         config->scan_bytes = iio_compute_scan_bytes(indio_dev,
 776                                     scan_mask, scan_timestamp);
 777         config->scan_mask = scan_mask;
 778         config->scan_timestamp = scan_timestamp;
 779
 780         return 0;
 781 }
 782
 783 /**
 784  * struct iio_demux_table - table describing demux memcpy ops
 785  * @from:       index to copy from
 786  * @to:         index to copy to
 787  * @length:     how many bytes to copy
 788  * @l:          list head used for management
 789  */
 790 struct iio_demux_table {
 791         unsigned from;
 792         unsigned to;
 793         unsigned length;
 794         struct list_head l;
 795 };
 796
 797 static void iio_buffer_demux_free(struct iio_buffer *buffer)
 798 {
 799         struct iio_demux_table *p, *q;
 800         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
 801                 list_del(&p->l);
 802                 kfree(p);
 803         }
 804 }
 805
 806 static int iio_buffer_add_demux(struct iio_buffer *buffer,
 807         struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
 808         unsigned int length)
 809 {
 810
 811         if (*p && (*p)->from + (*p)->length == in_loc &&
 812                 (*p)->to + (*p)->length == out_loc) {
 813                 (*p)->length += length;
 814         } else {
 815                 *p = kmalloc(sizeof(**p), GFP_KERNEL);
 816                 if (*p == NULL)
 817                         return -ENOMEM;
 818                 (*p)->from = in_loc;
 819                 (*p)->to = out_loc;
 820                 (*p)->length = length;
 821                 list_add_tail(&(*p)->l, &buffer->demux_list);
 822         }
 823
 824         return 0;
 825 }
 826
 827 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
 828                                    struct iio_buffer *buffer)
 829 {
 830         int ret, in_ind = -1, out_ind, length;
 831         unsigned in_loc = 0, out_loc = 0;
 832         struct iio_demux_table *p = NULL;
 833
 834         /* Clear out any old demux */
 835         iio_buffer_demux_free(buffer);
 836         kfree(buffer->demux_bounce);
 837         buffer->demux_bounce = NULL;
 838
 839         /* First work out which scan mode we will actually have */
 840         if (bitmap_equal(indio_dev->active_scan_mask,
 841                          buffer->scan_mask,
 842                          indio_dev->masklength))
 843                 return 0;
 844
 845         /* Now we have the two masks, work from least sig and build up sizes */
 846         for_each_set_bit(out_ind,
 847                          buffer->scan_mask,
 848                          indio_dev->masklength) {
 849                 in_ind = find_next_bit(indio_dev->active_scan_mask,
 850                                        indio_dev->masklength,
 851                                        in_ind + 1);
 852                 while (in_ind != out_ind) {
 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                         in_ind = find_next_bit(indio_dev->active_scan_mask,
 857                                                indio_dev->masklength,
 858                                                in_ind + 1);
 859                 }
 860                 length = iio_storage_bytes_for_si(indio_dev, in_ind);
 861                 out_loc = roundup(out_loc, length);
 862                 in_loc = roundup(in_loc, length);
 863                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
 864                 if (ret)
 865                         goto error_clear_mux_table;
 866                 out_loc += length;
 867                 in_loc += length;
 868         }
 869         /* Relies on scan_timestamp being last */
 870         if (buffer->scan_timestamp) {
 871                 length = iio_storage_bytes_for_timestamp(indio_dev);
 872                 out_loc = roundup(out_loc, length);
 873                 in_loc = roundup(in_loc, length);
 874                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
 875                 if (ret)
 876                         goto error_clear_mux_table;
 877                 out_loc += length;
 878                 in_loc += length;
 879         }
 880         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
 881         if (buffer->demux_bounce == NULL) {
 882                 ret = -ENOMEM;
 883                 goto error_clear_mux_table;
 884         }
 885         return 0;
 886
 887 error_clear_mux_table:
 888         iio_buffer_demux_free(buffer);
 889
 890         return ret;
 891 }
 892
 893 static int iio_update_demux(struct iio_dev *indio_dev)
 894 {
 895         struct iio_buffer *buffer;
 896         int ret;
 897
 898         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 899                 ret = iio_buffer_update_demux(indio_dev, buffer);
 900                 if (ret < 0)
 901                         goto error_clear_mux_table;
 902         }
 903         return 0;
 904
 905 error_clear_mux_table:
 906         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
 907                 iio_buffer_demux_free(buffer);
 908
 909         return ret;
 910 }
 911
 912 static int iio_enable_buffers(struct iio_dev *indio_dev,
 913         struct iio_device_config *config)
 914 {
 915         struct iio_buffer *buffer;
 916         int ret;
 917
 918         indio_dev->active_scan_mask = config->scan_mask;
 919         indio_dev->scan_timestamp = config->scan_timestamp;
 920         indio_dev->scan_bytes = config->scan_bytes;
 921
 922         iio_update_demux(indio_dev);
 923
 924         /* Wind up again */
 925         if (indio_dev->setup_ops->preenable) {
 926                 ret = indio_dev->setup_ops->preenable(indio_dev);
 927                 if (ret) {
 928                         dev_dbg(&indio_dev->dev,
 929                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 930                         goto err_undo_config;
 931                 }
 932         }
 933
 934         if (indio_dev->info->update_scan_mode) {
 935                 ret = indio_dev->info
 936                         ->update_scan_mode(indio_dev,
 937                                            indio_dev->active_scan_mask);
 938                 if (ret < 0) {
 939                         dev_dbg(&indio_dev->dev,
 940                                 "Buffer not started: update scan mode failed (%d)\n",
 941                                 ret);
 942                         goto err_run_postdisable;
 943                 }
 944         }
 945
 946         if (indio_dev->info->hwfifo_set_watermark)
 947                 indio_dev->info->hwfifo_set_watermark(indio_dev,
 948                         config->watermark);
 949
 950         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 951                 ret = iio_buffer_enable(buffer, indio_dev);
 952                 if (ret)
 953                         goto err_disable_buffers;
 954         }
 955
 956         indio_dev->currentmode = config->mode;
 957
 958         if (indio_dev->setup_ops->postenable) {
 959                 ret = indio_dev->setup_ops->postenable(indio_dev);
 960                 if (ret) {
 961                         dev_dbg(&indio_dev->dev,
 962                                "Buffer not started: postenable failed (%d)\n", ret);
 963                         goto err_disable_buffers;
 964                 }
 965         }
 966
 967         return 0;
 968
 969 err_disable_buffers:
 970         list_for_each_entry_continue_reverse(buffer, &indio_dev->buffer_list,
 971                                              buffer_list)
 972                 iio_buffer_disable(buffer, indio_dev);
 973 err_run_postdisable:
 974         indio_dev->currentmode = INDIO_DIRECT_MODE;
 975         if (indio_dev->setup_ops->postdisable)
 976                 indio_dev->setup_ops->postdisable(indio_dev);
 977 err_undo_config:
 978         indio_dev->active_scan_mask = NULL;
 979
 980         return ret;
 981 }
 982
 983 static int iio_disable_buffers(struct iio_dev *indio_dev)
 984 {
 985         struct iio_buffer *buffer;
 986         int ret = 0;
 987         int ret2;
 988
 989         /* Wind down existing buffers - iff there are any */
 990         if (list_empty(&indio_dev->buffer_list))
 991                 return 0;
 992
 993         /*
 994          * If things go wrong at some step in disable we still need to continue
 995          * to perform the other steps, otherwise we leave the device in a
 996          * inconsistent state. We return the error code for the first error we
 997          * encountered.
 998          */
 999
1000         if (indio_dev->setup_ops->predisable) {
1001                 ret2 = indio_dev->setup_ops->predisable(indio_dev);
1002                 if (ret2 && !ret)
1003                         ret = ret2;
1004         }
1005
1006         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1007                 ret2 = iio_buffer_disable(buffer, indio_dev);
1008                 if (ret2 && !ret)
1009                         ret = ret2;
1010         }
1011
1012         indio_dev->currentmode = INDIO_DIRECT_MODE;
1013
1014         if (indio_dev->setup_ops->postdisable) {
1015                 ret2 = indio_dev->setup_ops->postdisable(indio_dev);
1016                 if (ret2 && !ret)
1017                         ret = ret2;
1018         }
1019
1020         iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
1021         indio_dev->active_scan_mask = NULL;
1022
1023         return ret;
1024 }
1025
1026 static int __iio_update_buffers(struct iio_dev *indio_dev,
1027                        struct iio_buffer *insert_buffer,
1028                        struct iio_buffer *remove_buffer)
1029 {
1030         struct iio_device_config new_config;
1031         int ret;
1032
1033         ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
1034                 &new_config);
1035         if (ret)
1036                 return ret;
1037
1038         if (insert_buffer) {
1039                 ret = iio_buffer_request_update(indio_dev, insert_buffer);
1040                 if (ret)
1041                         goto err_free_config;
1042         }
1043
1044         ret = iio_disable_buffers(indio_dev);
1045         if (ret)
1046                 goto err_deactivate_all;
1047
1048         if (remove_buffer)
1049                 iio_buffer_deactivate(remove_buffer);
1050         if (insert_buffer)
1051                 iio_buffer_activate(indio_dev, insert_buffer);
1052
1053         /* If no buffers in list, we are done */
1054         if (list_empty(&indio_dev->buffer_list))
1055                 return 0;
1056
1057         ret = iio_enable_buffers(indio_dev, &new_config);
1058         if (ret)
1059                 goto err_deactivate_all;
1060
1061         return 0;
1062
1063 err_deactivate_all:
1064         /*
1065          * We've already verified that the config is valid earlier. If things go
1066          * wrong in either enable or disable the most likely reason is an IO
1067          * error from the device. In this case there is no good recovery
1068          * strategy. Just make sure to disable everything and leave the device
1069          * in a sane state.  With a bit of luck the device might come back to
1070          * life again later and userspace can try again.
1071          */
1072         iio_buffer_deactivate_all(indio_dev);
1073
1074 err_free_config:
1075         iio_free_scan_mask(indio_dev, new_config.scan_mask);
1076         return ret;
1077 }
1078
1079 int iio_update_buffers(struct iio_dev *indio_dev,
1080                        struct iio_buffer *insert_buffer,
1081                        struct iio_buffer *remove_buffer)
1082 {
1083         int ret;
1084
1085         if (insert_buffer == remove_buffer)
1086                 return 0;
1087
1088         mutex_lock(&indio_dev->info_exist_lock);
1089         mutex_lock(&indio_dev->mlock);
1090
1091         if (insert_buffer && iio_buffer_is_active(insert_buffer))
1092                 insert_buffer = NULL;
1093
1094         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
1095                 remove_buffer = NULL;
1096
1097         if (!insert_buffer && !remove_buffer) {
1098                 ret = 0;
1099                 goto out_unlock;
1100         }
1101
1102         if (indio_dev->info == NULL) {
1103                 ret = -ENODEV;
1104                 goto out_unlock;
1105         }
1106
1107         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
1108
1109 out_unlock:
1110         mutex_unlock(&indio_dev->mlock);
1111         mutex_unlock(&indio_dev->info_exist_lock);
1112
1113         return ret;
1114 }
1115 EXPORT_SYMBOL_GPL(iio_update_buffers);
1116
1117 void iio_disable_all_buffers(struct iio_dev *indio_dev)
1118 {
1119         iio_disable_buffers(indio_dev);
1120         iio_buffer_deactivate_all(indio_dev);
1121 }
1122
1123 static ssize_t iio_buffer_store_enable(struct device *dev,
1124                                        struct device_attribute *attr,
1125                                        const char *buf,
1126                                        size_t len)
1127 {
1128         int ret;
1129         bool requested_state;
1130         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1131         bool inlist;
1132
1133         ret = strtobool(buf, &requested_state);
1134         if (ret < 0)
1135                 return ret;
1136
1137         mutex_lock(&indio_dev->mlock);
1138
1139         /* Find out if it is in the list */
1140         inlist = iio_buffer_is_active(indio_dev->buffer);
1141         /* Already in desired state */
1142         if (inlist == requested_state)
1143                 goto done;
1144
1145         if (requested_state)
1146                 ret = __iio_update_buffers(indio_dev,
1147                                          indio_dev->buffer, NULL);
1148         else
1149                 ret = __iio_update_buffers(indio_dev,
1150                                          NULL, indio_dev->buffer);
1151
1152 done:
1153         mutex_unlock(&indio_dev->mlock);
1154         return (ret < 0) ? ret : len;
1155 }
1156
1157 static const char * const iio_scan_elements_group_name = "scan_elements";
1158
1159 static ssize_t iio_buffer_show_watermark(struct device *dev,
1160                                          struct device_attribute *attr,
1161                                          char *buf)
1162 {
1163         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1164         struct iio_buffer *buffer = indio_dev->buffer;
1165
1166         return sprintf(buf, "%u\n", buffer->watermark);
1167 }
1168
1169 static ssize_t iio_buffer_store_watermark(struct device *dev,
1170                                           struct device_attribute *attr,
1171                                           const char *buf,
1172                                           size_t len)
1173 {
1174         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1175         struct iio_buffer *buffer = indio_dev->buffer;
1176         unsigned int val;
1177         int ret;
1178
1179         ret = kstrtouint(buf, 10, &val);
1180         if (ret)
1181                 return ret;
1182         if (!val)
1183                 return -EINVAL;
1184
1185         mutex_lock(&indio_dev->mlock);
1186
1187         if (val > buffer->length) {
1188                 ret = -EINVAL;
1189                 goto out;
1190         }
1191
1192         if (iio_buffer_is_active(indio_dev->buffer)) {
1193                 ret = -EBUSY;
1194                 goto out;
1195         }
1196
1197         buffer->watermark = val;
1198 out:
1199         mutex_unlock(&indio_dev->mlock);
1200
1201         return ret ? ret : len;
1202 }
1203
1204 static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
1205                    iio_buffer_write_length);
1206 static struct device_attribute dev_attr_length_ro = __ATTR(length,
1207         S_IRUGO, iio_buffer_read_length, NULL);
1208 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
1209                    iio_buffer_show_enable, iio_buffer_store_enable);
1210 static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
1211                    iio_buffer_show_watermark, iio_buffer_store_watermark);
1212 static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
1213         S_IRUGO, iio_buffer_show_watermark, NULL);
1214
1215 static struct attribute *iio_buffer_attrs[] = {
1216         &dev_attr_length.attr,
1217         &dev_attr_enable.attr,
1218         &dev_attr_watermark.attr,
1219 };
1220
1221 int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
1222 {
1223         struct iio_dev_attr *p;
1224         struct attribute **attr;
1225         struct iio_buffer *buffer = indio_dev->buffer;
1226         int ret, i, attrn, attrcount, attrcount_orig = 0;
1227         const struct iio_chan_spec *channels;
1228
1229         channels = indio_dev->channels;
1230         if (channels) {
1231                 int ml = indio_dev->masklength;
1232
1233                 for (i = 0; i < indio_dev->num_channels; i++)
1234                         ml = max(ml, channels[i].scan_index + 1);
1235                 indio_dev->masklength = ml;
1236         }
1237
1238         if (!buffer)
1239                 return 0;
1240
1241         attrcount = 0;
1242         if (buffer->attrs) {
1243                 while (buffer->attrs[attrcount] != NULL)
1244                         attrcount++;
1245         }
1246
1247         attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
1248                        sizeof(struct attribute *), GFP_KERNEL);
1249         if (!attr)
1250                 return -ENOMEM;
1251
1252         memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1253         if (!buffer->access->set_length)
1254                 attr[0] = &dev_attr_length_ro.attr;
1255
1256         if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
1257                 attr[2] = &dev_attr_watermark_ro.attr;
1258
1259         if (buffer->attrs)
1260                 memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
1261                        sizeof(struct attribute *) * attrcount);
1262
1263         attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
1264
1265         buffer->buffer_group.name = "buffer";
1266         buffer->buffer_group.attrs = attr;
1267
1268         indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
1269
1270         if (buffer->scan_el_attrs != NULL) {
1271                 attr = buffer->scan_el_attrs->attrs;
1272                 while (*attr++ != NULL)
1273                         attrcount_orig++;
1274         }
1275         attrcount = attrcount_orig;
1276         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
1277         channels = indio_dev->channels;
1278         if (channels) {
1279                 /* new magic */
1280                 for (i = 0; i < indio_dev->num_channels; i++) {
1281                         if (channels[i].scan_index < 0)
1282                                 continue;
1283
1284                         ret = iio_buffer_add_channel_sysfs(indio_dev,
1285                                                          &channels[i]);
1286                         if (ret < 0)
1287                                 goto error_cleanup_dynamic;
1288                         attrcount += ret;
1289                         if (channels[i].type == IIO_TIMESTAMP)
1290                                 indio_dev->scan_index_timestamp =
1291                                         channels[i].scan_index;
1292                 }
1293                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
1294                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
1295                                                     sizeof(*buffer->scan_mask),
1296                                                     GFP_KERNEL);
1297                         if (buffer->scan_mask == NULL) {
1298                                 ret = -ENOMEM;
1299                                 goto error_cleanup_dynamic;
1300                         }
1301                 }
1302         }
1303
1304         buffer->scan_el_group.name = iio_scan_elements_group_name;
1305
1306         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
1307                                               sizeof(buffer->scan_el_group.attrs[0]),
1308                                               GFP_KERNEL);
1309         if (buffer->scan_el_group.attrs == NULL) {
1310                 ret = -ENOMEM;
1311                 goto error_free_scan_mask;
1312         }
1313         if (buffer->scan_el_attrs)
1314                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
1315                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
1316         attrn = attrcount_orig;
1317
1318         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
1319                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
1320         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
1321
1322         return 0;
1323
1324 error_free_scan_mask:
1325         kfree(buffer->scan_mask);
1326 error_cleanup_dynamic:
1327         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
1328         kfree(indio_dev->buffer->buffer_group.attrs);
1329
1330         return ret;
1331 }
1332
1333 void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
1334 {
1335         if (!indio_dev->buffer)
1336                 return;
1337
1338         kfree(indio_dev->buffer->scan_mask);
1339         kfree(indio_dev->buffer->buffer_group.attrs);
1340         kfree(indio_dev->buffer->scan_el_group.attrs);
1341         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
1342 }
1343
1344 /**
1345  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1346  * @indio_dev: the iio device
1347  * @mask: scan mask to be checked
1348  *
1349  * Return true if exactly one bit is set in the scan mask, false otherwise. It
1350  * can be used for devices where only one channel can be active for sampling at
1351  * a time.
1352  */
1353 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1354         const unsigned long *mask)
1355 {
1356         return bitmap_weight(mask, indio_dev->masklength) == 1;
1357 }
1358 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1359
1360 static const void *iio_demux(struct iio_buffer *buffer,
1361                                  const void *datain)
1362 {
1363         struct iio_demux_table *t;
1364
1365         if (list_empty(&buffer->demux_list))
1366                 return datain;
1367         list_for_each_entry(t, &buffer->demux_list, l)
1368                 memcpy(buffer->demux_bounce + t->to,
1369                        datain + t->from, t->length);
1370
1371         return buffer->demux_bounce;
1372 }
1373
1374 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1375 {
1376         const void *dataout = iio_demux(buffer, data);
1377         int ret;
1378
1379         ret = buffer->access->store_to(buffer, dataout);
1380         if (ret)
1381                 return ret;
1382
1383         /*
1384          * We can't just test for watermark to decide if we wake the poll queue
1385          * because read may request less samples than the watermark.
1386          */
1387         wake_up_interruptible_poll(&buffer->pollq, POLLIN | POLLRDNORM);
1388         return 0;
1389 }
1390
1391 /**
1392  * iio_push_to_buffers() - push to a registered buffer.
1393  * @indio_dev:          iio_dev structure for device.
1394  * @data:               Full scan.
1395  */
1396 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1397 {
1398         int ret;
1399         struct iio_buffer *buf;
1400
1401         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
1402                 ret = iio_push_to_buffer(buf, data);
1403                 if (ret < 0)
1404                         return ret;
1405         }
1406
1407         return 0;
1408 }
1409 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1410
1411 /**
1412  * iio_buffer_release() - Free a buffer's resources
1413  * @ref: Pointer to the kref embedded in the iio_buffer struct
1414  *
1415  * This function is called when the last reference to the buffer has been
1416  * dropped. It will typically free all resources allocated by the buffer. Do not
1417  * call this function manually, always use iio_buffer_put() when done using a
1418  * buffer.
1419  */
1420 static void iio_buffer_release(struct kref *ref)
1421 {
1422         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1423
1424         buffer->access->release(buffer);
1425 }
1426
1427 /**
1428  * iio_buffer_get() - Grab a reference to the buffer
1429  * @buffer: The buffer to grab a reference for, may be NULL
1430  *
1431  * Returns the pointer to the buffer that was passed into the function.
1432  */
1433 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1434 {
1435         if (buffer)
1436                 kref_get(&buffer->ref);
1437
1438         return buffer;
1439 }
1440 EXPORT_SYMBOL_GPL(iio_buffer_get);
1441
1442 /**
1443  * iio_buffer_put() - Release the reference to the buffer
1444  * @buffer: The buffer to release the reference for, may be NULL
1445  */
1446 void iio_buffer_put(struct iio_buffer *buffer)
1447 {
1448         if (buffer)
1449                 kref_put(&buffer->ref, iio_buffer_release);
1450 }
1451 EXPORT_SYMBOL_GPL(iio_buffer_put);
1452
1453 /**
1454  * iio_device_attach_buffer - Attach a buffer to a IIO device
1455  * @indio_dev: The device the buffer should be attached to
1456  * @buffer: The buffer to attach to the device
1457  *
1458  * This function attaches a buffer to a IIO device. The buffer stays attached to
1459  * the device until the device is freed. The function should only be called at
1460  * most once per device.
1461  */
1462 void iio_device_attach_buffer(struct iio_dev *indio_dev,
1463                               struct iio_buffer *buffer)
1464 {
1465         indio_dev->buffer = iio_buffer_get(buffer);
1466 }
1467 EXPORT_SYMBOL_GPL(iio_device_attach_buffer);