drivers/iio/industrialio-buffer.c

   1 /* The industrial I/O core
   2  *
   3  * Copyright (c) 2008 Jonathan Cameron
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * Handling of buffer allocation / resizing.
  10  *
  11  *
  12  * Things to look at here.
  13  * - Better memory allocation techniques?
  14  * - Alternative access techniques?
  15  */
  16 #include <linux/kernel.h>
  17 #include <linux/export.h>
  18 #include <linux/device.h>
  19 #include <linux/fs.h>
  20 #include <linux/cdev.h>
  21 #include <linux/slab.h>
  22 #include <linux/poll.h>
  23 #include <linux/sched.h>
  24
  25 #include <linux/iio/iio.h>
  26 #include "iio_core.h"
  27 #include <linux/iio/sysfs.h>
  28 #include <linux/iio/buffer.h>
  29
  30 static const char * const iio_endian_prefix[] = {
  31         [IIO_BE] = "be",
  32         [IIO_LE] = "le",
  33 };
  34
  35 static bool iio_buffer_is_active(struct iio_buffer *buf)
  36 {
  37         return !list_empty(&buf->buffer_list);
  38 }
  39
  40 static bool iio_buffer_data_available(struct iio_buffer *buf)
  41 {
  42         if (buf->access->data_available)
  43                 return buf->access->data_available(buf);
  44
  45         return buf->stufftoread;
  46 }
  47
  48 /**
  49  * iio_buffer_read_first_n_outer() - chrdev read for buffer access
  50  *
  51  * This function relies on all buffer implementations having an
  52  * iio_buffer as their first element.
  53  **/
  54 ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
  55                                       size_t n, loff_t *f_ps)
  56 {
  57         struct iio_dev *indio_dev = filp->private_data;
  58         struct iio_buffer *rb = indio_dev->buffer;
  59         int ret;
  60
  61         if (!indio_dev->info)
  62                 return -ENODEV;
  63
  64         if (!rb || !rb->access->read_first_n)
  65                 return -EINVAL;
  66
  67         do {
  68                 if (!iio_buffer_data_available(rb)) {
  69                         if (filp->f_flags & O_NONBLOCK)
  70                                 return -EAGAIN;
  71
  72                         ret = wait_event_interruptible(rb->pollq,
  73                                         iio_buffer_data_available(rb) ||
  74                                         indio_dev->info == NULL);
  75                         if (ret)
  76                                 return ret;
  77                         if (indio_dev->info == NULL)
  78                                 return -ENODEV;
  79                 }
  80
  81                 ret = rb->access->read_first_n(rb, n, buf);
  82                 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
  83                         ret = -EAGAIN;
  84          } while (ret == 0);
  85
  86         return ret;
  87 }
  88
  89 /**
  90  * iio_buffer_poll() - poll the buffer to find out if it has data
  91  */
  92 unsigned int iio_buffer_poll(struct file *filp,
  93                              struct poll_table_struct *wait)
  94 {
  95         struct iio_dev *indio_dev = filp->private_data;
  96         struct iio_buffer *rb = indio_dev->buffer;
  97
  98         if (!indio_dev->info)
  99                 return -ENODEV;
 100
 101         poll_wait(filp, &rb->pollq, wait);
 102         if (iio_buffer_data_available(rb))
 103                 return POLLIN | POLLRDNORM;
 104         /* need a way of knowing if there may be enough data... */
 105         return 0;
 106 }
 107
 108 /**
 109  * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
 110  * @indio_dev: The IIO device
 111  *
 112  * Wakes up the event waitqueue used for poll(). Should usually
 113  * be called when the device is unregistered.
 114  */
 115 void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
 116 {
 117         if (!indio_dev->buffer)
 118                 return;
 119
 120         wake_up(&indio_dev->buffer->pollq);
 121 }
 122
 123 void iio_buffer_init(struct iio_buffer *buffer)
 124 {
 125         INIT_LIST_HEAD(&buffer->demux_list);
 126         INIT_LIST_HEAD(&buffer->buffer_list);
 127         init_waitqueue_head(&buffer->pollq);
 128         kref_init(&buffer->ref);
 129 }
 130 EXPORT_SYMBOL(iio_buffer_init);
 131
 132 static ssize_t iio_show_scan_index(struct device *dev,
 133                                    struct device_attribute *attr,
 134                                    char *buf)
 135 {
 136         return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
 137 }
 138
 139 static ssize_t iio_show_fixed_type(struct device *dev,
 140                                    struct device_attribute *attr,
 141                                    char *buf)
 142 {
 143         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 144         u8 type = this_attr->c->scan_type.endianness;
 145
 146         if (type == IIO_CPU) {
 147 #ifdef __LITTLE_ENDIAN
 148                 type = IIO_LE;
 149 #else
 150                 type = IIO_BE;
 151 #endif
 152         }
 153         return sprintf(buf, "%s:%c%d/%d>>%u\n",
 154                        iio_endian_prefix[type],
 155                        this_attr->c->scan_type.sign,
 156                        this_attr->c->scan_type.realbits,
 157                        this_attr->c->scan_type.storagebits,
 158                        this_attr->c->scan_type.shift);
 159 }
 160
 161 static ssize_t iio_scan_el_show(struct device *dev,
 162                                 struct device_attribute *attr,
 163                                 char *buf)
 164 {
 165         int ret;
 166         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 167
 168         ret = test_bit(to_iio_dev_attr(attr)->address,
 169                        indio_dev->buffer->scan_mask);
 170
 171         return sprintf(buf, "%d\n", ret);
 172 }
 173
 174 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 175 {
 176         clear_bit(bit, buffer->scan_mask);
 177         return 0;
 178 }
 179
 180 static ssize_t iio_scan_el_store(struct device *dev,
 181                                  struct device_attribute *attr,
 182                                  const char *buf,
 183                                  size_t len)
 184 {
 185         int ret;
 186         bool state;
 187         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 188         struct iio_buffer *buffer = indio_dev->buffer;
 189         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 190
 191         ret = strtobool(buf, &state);
 192         if (ret < 0)
 193                 return ret;
 194         mutex_lock(&indio_dev->mlock);
 195         if (iio_buffer_is_active(indio_dev->buffer)) {
 196                 ret = -EBUSY;
 197                 goto error_ret;
 198         }
 199         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 200         if (ret < 0)
 201                 goto error_ret;
 202         if (!state && ret) {
 203                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 204                 if (ret)
 205                         goto error_ret;
 206         } else if (state && !ret) {
 207                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 208                 if (ret)
 209                         goto error_ret;
 210         }
 211
 212 error_ret:
 213         mutex_unlock(&indio_dev->mlock);
 214
 215         return ret < 0 ? ret : len;
 216
 217 }
 218
 219 static ssize_t iio_scan_el_ts_show(struct device *dev,
 220                                    struct device_attribute *attr,
 221                                    char *buf)
 222 {
 223         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 224         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 225 }
 226
 227 static ssize_t iio_scan_el_ts_store(struct device *dev,
 228                                     struct device_attribute *attr,
 229                                     const char *buf,
 230                                     size_t len)
 231 {
 232         int ret;
 233         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 234         bool state;
 235
 236         ret = strtobool(buf, &state);
 237         if (ret < 0)
 238                 return ret;
 239
 240         mutex_lock(&indio_dev->mlock);
 241         if (iio_buffer_is_active(indio_dev->buffer)) {
 242                 ret = -EBUSY;
 243                 goto error_ret;
 244         }
 245         indio_dev->buffer->scan_timestamp = state;
 246 error_ret:
 247         mutex_unlock(&indio_dev->mlock);
 248
 249         return ret ? ret : len;
 250 }
 251
 252 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 253                                         const struct iio_chan_spec *chan)
 254 {
 255         int ret, attrcount = 0;
 256         struct iio_buffer *buffer = indio_dev->buffer;
 257
 258         ret = __iio_add_chan_devattr("index",
 259                                      chan,
 260                                      &iio_show_scan_index,
 261                                      NULL,
 262                                      0,
 263                                      IIO_SEPARATE,
 264                                      &indio_dev->dev,
 265                                      &buffer->scan_el_dev_attr_list);
 266         if (ret)
 267                 goto error_ret;
 268         attrcount++;
 269         ret = __iio_add_chan_devattr("type",
 270                                      chan,
 271                                      &iio_show_fixed_type,
 272                                      NULL,
 273                                      0,
 274                                      0,
 275                                      &indio_dev->dev,
 276                                      &buffer->scan_el_dev_attr_list);
 277         if (ret)
 278                 goto error_ret;
 279         attrcount++;
 280         if (chan->type != IIO_TIMESTAMP)
 281                 ret = __iio_add_chan_devattr("en",
 282                                              chan,
 283                                              &iio_scan_el_show,
 284                                              &iio_scan_el_store,
 285                                              chan->scan_index,
 286                                              0,
 287                                              &indio_dev->dev,
 288                                              &buffer->scan_el_dev_attr_list);
 289         else
 290                 ret = __iio_add_chan_devattr("en",
 291                                              chan,
 292                                              &iio_scan_el_ts_show,
 293                                              &iio_scan_el_ts_store,
 294                                              chan->scan_index,
 295                                              0,
 296                                              &indio_dev->dev,
 297                                              &buffer->scan_el_dev_attr_list);
 298         if (ret)
 299                 goto error_ret;
 300         attrcount++;
 301         ret = attrcount;
 302 error_ret:
 303         return ret;
 304 }
 305
 306 static const char * const iio_scan_elements_group_name = "scan_elements";
 307
 308 int iio_buffer_register(struct iio_dev *indio_dev,
 309                         const struct iio_chan_spec *channels,
 310                         int num_channels)
 311 {
 312         struct iio_dev_attr *p;
 313         struct attribute **attr;
 314         struct iio_buffer *buffer = indio_dev->buffer;
 315         int ret, i, attrn, attrcount, attrcount_orig = 0;
 316
 317         if (buffer->attrs)
 318                 indio_dev->groups[indio_dev->groupcounter++] = buffer->attrs;
 319
 320         if (buffer->scan_el_attrs != NULL) {
 321                 attr = buffer->scan_el_attrs->attrs;
 322                 while (*attr++ != NULL)
 323                         attrcount_orig++;
 324         }
 325         attrcount = attrcount_orig;
 326         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
 327         if (channels) {
 328                 /* new magic */
 329                 for (i = 0; i < num_channels; i++) {
 330                         if (channels[i].scan_index < 0)
 331                                 continue;
 332
 333                         /* Establish necessary mask length */
 334                         if (channels[i].scan_index >
 335                             (int)indio_dev->masklength - 1)
 336                                 indio_dev->masklength
 337                                         = channels[i].scan_index + 1;
 338
 339                         ret = iio_buffer_add_channel_sysfs(indio_dev,
 340                                                          &channels[i]);
 341                         if (ret < 0)
 342                                 goto error_cleanup_dynamic;
 343                         attrcount += ret;
 344                         if (channels[i].type == IIO_TIMESTAMP)
 345                                 indio_dev->scan_index_timestamp =
 346                                         channels[i].scan_index;
 347                 }
 348                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
 349                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 350                                                     sizeof(*buffer->scan_mask),
 351                                                     GFP_KERNEL);
 352                         if (buffer->scan_mask == NULL) {
 353                                 ret = -ENOMEM;
 354                                 goto error_cleanup_dynamic;
 355                         }
 356                 }
 357         }
 358
 359         buffer->scan_el_group.name = iio_scan_elements_group_name;
 360
 361         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
 362                                               sizeof(buffer->scan_el_group.attrs[0]),
 363                                               GFP_KERNEL);
 364         if (buffer->scan_el_group.attrs == NULL) {
 365                 ret = -ENOMEM;
 366                 goto error_free_scan_mask;
 367         }
 368         if (buffer->scan_el_attrs)
 369                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
 370                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
 371         attrn = attrcount_orig;
 372
 373         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
 374                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
 375         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
 376
 377         return 0;
 378
 379 error_free_scan_mask:
 380         kfree(buffer->scan_mask);
 381 error_cleanup_dynamic:
 382         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
 383
 384         return ret;
 385 }
 386 EXPORT_SYMBOL(iio_buffer_register);
 387
 388 void iio_buffer_unregister(struct iio_dev *indio_dev)
 389 {
 390         kfree(indio_dev->buffer->scan_mask);
 391         kfree(indio_dev->buffer->scan_el_group.attrs);
 392         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
 393 }
 394 EXPORT_SYMBOL(iio_buffer_unregister);
 395
 396 ssize_t iio_buffer_read_length(struct device *dev,
 397                                struct device_attribute *attr,
 398                                char *buf)
 399 {
 400         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 401         struct iio_buffer *buffer = indio_dev->buffer;
 402
 403         if (buffer->access->get_length)
 404                 return sprintf(buf, "%d\n",
 405                                buffer->access->get_length(buffer));
 406
 407         return 0;
 408 }
 409 EXPORT_SYMBOL(iio_buffer_read_length);
 410
 411 ssize_t iio_buffer_write_length(struct device *dev,
 412                                 struct device_attribute *attr,
 413                                 const char *buf,
 414                                 size_t len)
 415 {
 416         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 417         struct iio_buffer *buffer = indio_dev->buffer;
 418         unsigned int val;
 419         int ret;
 420
 421         ret = kstrtouint(buf, 10, &val);
 422         if (ret)
 423                 return ret;
 424
 425         if (buffer->access->get_length)
 426                 if (val == buffer->access->get_length(buffer))
 427                         return len;
 428
 429         mutex_lock(&indio_dev->mlock);
 430         if (iio_buffer_is_active(indio_dev->buffer)) {
 431                 ret = -EBUSY;
 432         } else {
 433                 if (buffer->access->set_length)
 434                         buffer->access->set_length(buffer, val);
 435                 ret = 0;
 436         }
 437         mutex_unlock(&indio_dev->mlock);
 438
 439         return ret ? ret : len;
 440 }
 441 EXPORT_SYMBOL(iio_buffer_write_length);
 442
 443 ssize_t iio_buffer_show_enable(struct device *dev,
 444                                struct device_attribute *attr,
 445                                char *buf)
 446 {
 447         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 448         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 449 }
 450 EXPORT_SYMBOL(iio_buffer_show_enable);
 451
 452 /* Note NULL used as error indicator as it doesn't make sense. */
 453 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
 454                                           unsigned int masklength,
 455                                           const unsigned long *mask)
 456 {
 457         if (bitmap_empty(mask, masklength))
 458                 return NULL;
 459         while (*av_masks) {
 460                 if (bitmap_subset(mask, av_masks, masklength))
 461                         return av_masks;
 462                 av_masks += BITS_TO_LONGS(masklength);
 463         }
 464         return NULL;
 465 }
 466
 467 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 468                                 const unsigned long *mask, bool timestamp)
 469 {
 470         const struct iio_chan_spec *ch;
 471         unsigned bytes = 0;
 472         int length, i;
 473
 474         /* How much space will the demuxed element take? */
 475         for_each_set_bit(i, mask,
 476                          indio_dev->masklength) {
 477                 ch = iio_find_channel_from_si(indio_dev, i);
 478                 length = ch->scan_type.storagebits / 8;
 479                 bytes = ALIGN(bytes, length);
 480                 bytes += length;
 481         }
 482         if (timestamp) {
 483                 ch = iio_find_channel_from_si(indio_dev,
 484                                               indio_dev->scan_index_timestamp);
 485                 length = ch->scan_type.storagebits / 8;
 486                 bytes = ALIGN(bytes, length);
 487                 bytes += length;
 488         }
 489         return bytes;
 490 }
 491
 492 static void iio_buffer_activate(struct iio_dev *indio_dev,
 493         struct iio_buffer *buffer)
 494 {
 495         iio_buffer_get(buffer);
 496         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 497 }
 498
 499 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 500 {
 501         list_del_init(&buffer->buffer_list);
 502         iio_buffer_put(buffer);
 503 }
 504
 505 void iio_disable_all_buffers(struct iio_dev *indio_dev)
 506 {
 507         struct iio_buffer *buffer, *_buffer;
 508
 509         if (list_empty(&indio_dev->buffer_list))
 510                 return;
 511
 512         if (indio_dev->setup_ops->predisable)
 513                 indio_dev->setup_ops->predisable(indio_dev);
 514
 515         list_for_each_entry_safe(buffer, _buffer,
 516                         &indio_dev->buffer_list, buffer_list)
 517                 iio_buffer_deactivate(buffer);
 518
 519         indio_dev->currentmode = INDIO_DIRECT_MODE;
 520         if (indio_dev->setup_ops->postdisable)
 521                 indio_dev->setup_ops->postdisable(indio_dev);
 522
 523         if (indio_dev->available_scan_masks == NULL)
 524                 kfree(indio_dev->active_scan_mask);
 525 }
 526
 527 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 528         struct iio_buffer *buffer)
 529 {
 530         unsigned int bytes;
 531
 532         if (!buffer->access->set_bytes_per_datum)
 533                 return;
 534
 535         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 536                 buffer->scan_timestamp);
 537
 538         buffer->access->set_bytes_per_datum(buffer, bytes);
 539 }
 540
 541 static int __iio_update_buffers(struct iio_dev *indio_dev,
 542                        struct iio_buffer *insert_buffer,
 543                        struct iio_buffer *remove_buffer)
 544 {
 545         int ret;
 546         int success = 0;
 547         struct iio_buffer *buffer;
 548         unsigned long *compound_mask;
 549         const unsigned long *old_mask;
 550
 551         /* Wind down existing buffers - iff there are any */
 552         if (!list_empty(&indio_dev->buffer_list)) {
 553                 if (indio_dev->setup_ops->predisable) {
 554                         ret = indio_dev->setup_ops->predisable(indio_dev);
 555                         if (ret)
 556                                 goto error_ret;
 557                 }
 558                 indio_dev->currentmode = INDIO_DIRECT_MODE;
 559                 if (indio_dev->setup_ops->postdisable) {
 560                         ret = indio_dev->setup_ops->postdisable(indio_dev);
 561                         if (ret)
 562                                 goto error_ret;
 563                 }
 564         }
 565         /* Keep a copy of current setup to allow roll back */
 566         old_mask = indio_dev->active_scan_mask;
 567         if (!indio_dev->available_scan_masks)
 568                 indio_dev->active_scan_mask = NULL;
 569
 570         if (remove_buffer)
 571                 iio_buffer_deactivate(remove_buffer);
 572         if (insert_buffer)
 573                 iio_buffer_activate(indio_dev, insert_buffer);
 574
 575         /* If no buffers in list, we are done */
 576         if (list_empty(&indio_dev->buffer_list)) {
 577                 indio_dev->currentmode = INDIO_DIRECT_MODE;
 578                 if (indio_dev->available_scan_masks == NULL)
 579                         kfree(old_mask);
 580                 return 0;
 581         }
 582
 583         /* What scan mask do we actually have? */
 584         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 585                                 sizeof(long), GFP_KERNEL);
 586         if (compound_mask == NULL) {
 587                 if (indio_dev->available_scan_masks == NULL)
 588                         kfree(old_mask);
 589                 return -ENOMEM;
 590         }
 591         indio_dev->scan_timestamp = 0;
 592
 593         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 594                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 595                           indio_dev->masklength);
 596                 indio_dev->scan_timestamp |= buffer->scan_timestamp;
 597         }
 598         if (indio_dev->available_scan_masks) {
 599                 indio_dev->active_scan_mask =
 600                         iio_scan_mask_match(indio_dev->available_scan_masks,
 601                                             indio_dev->masklength,
 602                                             compound_mask);
 603                 if (indio_dev->active_scan_mask == NULL) {
 604                         /*
 605                          * Roll back.
 606                          * Note can only occur when adding a buffer.
 607                          */
 608                         iio_buffer_deactivate(insert_buffer);
 609                         if (old_mask) {
 610                                 indio_dev->active_scan_mask = old_mask;
 611                                 success = -EINVAL;
 612                         }
 613                         else {
 614                                 kfree(compound_mask);
 615                                 ret = -EINVAL;
 616                                 goto error_ret;
 617                         }
 618                 }
 619         } else {
 620                 indio_dev->active_scan_mask = compound_mask;
 621         }
 622
 623         iio_update_demux(indio_dev);
 624
 625         /* Wind up again */
 626         if (indio_dev->setup_ops->preenable) {
 627                 ret = indio_dev->setup_ops->preenable(indio_dev);
 628                 if (ret) {
 629                         printk(KERN_ERR
 630                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 631                         goto error_remove_inserted;
 632                 }
 633         }
 634         indio_dev->scan_bytes =
 635                 iio_compute_scan_bytes(indio_dev,
 636                                        indio_dev->active_scan_mask,
 637                                        indio_dev->scan_timestamp);
 638         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 639                 iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 640                 if (buffer->access->request_update) {
 641                         ret = buffer->access->request_update(buffer);
 642                         if (ret) {
 643                                 printk(KERN_INFO
 644                                        "Buffer not started: buffer parameter update failed (%d)\n", ret);
 645                                 goto error_run_postdisable;
 646                         }
 647                 }
 648         }
 649         if (indio_dev->info->update_scan_mode) {
 650                 ret = indio_dev->info
 651                         ->update_scan_mode(indio_dev,
 652                                            indio_dev->active_scan_mask);
 653                 if (ret < 0) {
 654                         printk(KERN_INFO "Buffer not started: update scan mode failed (%d)\n", ret);
 655                         goto error_run_postdisable;
 656                 }
 657         }
 658         /* Definitely possible for devices to support both of these. */
 659         if (indio_dev->modes & INDIO_BUFFER_TRIGGERED) {
 660                 if (!indio_dev->trig) {
 661                         printk(KERN_INFO "Buffer not started: no trigger\n");
 662                         ret = -EINVAL;
 663                         /* Can only occur on first buffer */
 664                         goto error_run_postdisable;
 665                 }
 666                 indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
 667         } else if (indio_dev->modes & INDIO_BUFFER_HARDWARE) {
 668                 indio_dev->currentmode = INDIO_BUFFER_HARDWARE;
 669         } else { /* Should never be reached */
 670                 ret = -EINVAL;
 671                 goto error_run_postdisable;
 672         }
 673
 674         if (indio_dev->setup_ops->postenable) {
 675                 ret = indio_dev->setup_ops->postenable(indio_dev);
 676                 if (ret) {
 677                         printk(KERN_INFO
 678                                "Buffer not started: postenable failed (%d)\n", ret);
 679                         indio_dev->currentmode = INDIO_DIRECT_MODE;
 680                         if (indio_dev->setup_ops->postdisable)
 681                                 indio_dev->setup_ops->postdisable(indio_dev);
 682                         goto error_disable_all_buffers;
 683                 }
 684         }
 685
 686         if (indio_dev->available_scan_masks)
 687                 kfree(compound_mask);
 688         else
 689                 kfree(old_mask);
 690
 691         return success;
 692
 693 error_disable_all_buffers:
 694         indio_dev->currentmode = INDIO_DIRECT_MODE;
 695 error_run_postdisable:
 696         if (indio_dev->setup_ops->postdisable)
 697                 indio_dev->setup_ops->postdisable(indio_dev);
 698 error_remove_inserted:
 699
 700         if (insert_buffer)
 701                 iio_buffer_deactivate(insert_buffer);
 702         indio_dev->active_scan_mask = old_mask;
 703         kfree(compound_mask);
 704 error_ret:
 705
 706         return ret;
 707 }
 708
 709 int iio_update_buffers(struct iio_dev *indio_dev,
 710                        struct iio_buffer *insert_buffer,
 711                        struct iio_buffer *remove_buffer)
 712 {
 713         int ret;
 714
 715         if (insert_buffer == remove_buffer)
 716                 return 0;
 717
 718         mutex_lock(&indio_dev->info_exist_lock);
 719         mutex_lock(&indio_dev->mlock);
 720
 721         if (insert_buffer && iio_buffer_is_active(insert_buffer))
 722                 insert_buffer = NULL;
 723
 724         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
 725                 remove_buffer = NULL;
 726
 727         if (!insert_buffer && !remove_buffer) {
 728                 ret = 0;
 729                 goto out_unlock;
 730         }
 731
 732         if (indio_dev->info == NULL) {
 733                 ret = -ENODEV;
 734                 goto out_unlock;
 735         }
 736
 737         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 738
 739 out_unlock:
 740         mutex_unlock(&indio_dev->mlock);
 741         mutex_unlock(&indio_dev->info_exist_lock);
 742
 743         return ret;
 744 }
 745 EXPORT_SYMBOL_GPL(iio_update_buffers);
 746
 747 ssize_t iio_buffer_store_enable(struct device *dev,
 748                                 struct device_attribute *attr,
 749                                 const char *buf,
 750                                 size_t len)
 751 {
 752         int ret;
 753         bool requested_state;
 754         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 755         bool inlist;
 756
 757         ret = strtobool(buf, &requested_state);
 758         if (ret < 0)
 759                 return ret;
 760
 761         mutex_lock(&indio_dev->mlock);
 762
 763         /* Find out if it is in the list */
 764         inlist = iio_buffer_is_active(indio_dev->buffer);
 765         /* Already in desired state */
 766         if (inlist == requested_state)
 767                 goto done;
 768
 769         if (requested_state)
 770                 ret = __iio_update_buffers(indio_dev,
 771                                          indio_dev->buffer, NULL);
 772         else
 773                 ret = __iio_update_buffers(indio_dev,
 774                                          NULL, indio_dev->buffer);
 775
 776         if (ret < 0)
 777                 goto done;
 778 done:
 779         mutex_unlock(&indio_dev->mlock);
 780         return (ret < 0) ? ret : len;
 781 }
 782 EXPORT_SYMBOL(iio_buffer_store_enable);
 783
 784 /**
 785  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
 786  * @indio_dev: the iio device
 787  * @mask: scan mask to be checked
 788  *
 789  * Return true if exactly one bit is set in the scan mask, false otherwise. It
 790  * can be used for devices where only one channel can be active for sampling at
 791  * a time.
 792  */
 793 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 794         const unsigned long *mask)
 795 {
 796         return bitmap_weight(mask, indio_dev->masklength) == 1;
 797 }
 798 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
 799
 800 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
 801         const unsigned long *mask)
 802 {
 803         if (!indio_dev->setup_ops->validate_scan_mask)
 804                 return true;
 805
 806         return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
 807 }
 808
 809 /**
 810  * iio_scan_mask_set() - set particular bit in the scan mask
 811  * @indio_dev: the iio device
 812  * @buffer: the buffer whose scan mask we are interested in
 813  * @bit: the bit to be set.
 814  *
 815  * Note that at this point we have no way of knowing what other
 816  * buffers might request, hence this code only verifies that the
 817  * individual buffers request is plausible.
 818  */
 819 int iio_scan_mask_set(struct iio_dev *indio_dev,
 820                       struct iio_buffer *buffer, int bit)
 821 {
 822         const unsigned long *mask;
 823         unsigned long *trialmask;
 824
 825         trialmask = kmalloc(sizeof(*trialmask)*
 826                             BITS_TO_LONGS(indio_dev->masklength),
 827                             GFP_KERNEL);
 828
 829         if (trialmask == NULL)
 830                 return -ENOMEM;
 831         if (!indio_dev->masklength) {
 832                 WARN_ON("Trying to set scanmask prior to registering buffer\n");
 833                 goto err_invalid_mask;
 834         }
 835         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 836         set_bit(bit, trialmask);
 837
 838         if (!iio_validate_scan_mask(indio_dev, trialmask))
 839                 goto err_invalid_mask;
 840
 841         if (indio_dev->available_scan_masks) {
 842                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 843                                            indio_dev->masklength,
 844                                            trialmask);
 845                 if (!mask)
 846                         goto err_invalid_mask;
 847         }
 848         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 849
 850         kfree(trialmask);
 851
 852         return 0;
 853
 854 err_invalid_mask:
 855         kfree(trialmask);
 856         return -EINVAL;
 857 }
 858 EXPORT_SYMBOL_GPL(iio_scan_mask_set);
 859
 860 int iio_scan_mask_query(struct iio_dev *indio_dev,
 861                         struct iio_buffer *buffer, int bit)
 862 {
 863         if (bit > indio_dev->masklength)
 864                 return -EINVAL;
 865
 866         if (!buffer->scan_mask)
 867                 return 0;
 868
 869         return test_bit(bit, buffer->scan_mask);
 870 };
 871 EXPORT_SYMBOL_GPL(iio_scan_mask_query);
 872
 873 /**
 874  * struct iio_demux_table() - table describing demux memcpy ops
 875  * @from:       index to copy from
 876  * @to:         index to copy to
 877  * @length:     how many bytes to copy
 878  * @l:          list head used for management
 879  */
 880 struct iio_demux_table {
 881         unsigned from;
 882         unsigned to;
 883         unsigned length;
 884         struct list_head l;
 885 };
 886
 887 static const void *iio_demux(struct iio_buffer *buffer,
 888                                  const void *datain)
 889 {
 890         struct iio_demux_table *t;
 891
 892         if (list_empty(&buffer->demux_list))
 893                 return datain;
 894         list_for_each_entry(t, &buffer->demux_list, l)
 895                 memcpy(buffer->demux_bounce + t->to,
 896                        datain + t->from, t->length);
 897
 898         return buffer->demux_bounce;
 899 }
 900
 901 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
 902 {
 903         const void *dataout = iio_demux(buffer, data);
 904
 905         return buffer->access->store_to(buffer, dataout);
 906 }
 907
 908 static void iio_buffer_demux_free(struct iio_buffer *buffer)
 909 {
 910         struct iio_demux_table *p, *q;
 911         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
 912                 list_del(&p->l);
 913                 kfree(p);
 914         }
 915 }
 916
 917
 918 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
 919 {
 920         int ret;
 921         struct iio_buffer *buf;
 922
 923         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
 924                 ret = iio_push_to_buffer(buf, data);
 925                 if (ret < 0)
 926                         return ret;
 927         }
 928
 929         return 0;
 930 }
 931 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
 932
 933 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
 934                                    struct iio_buffer *buffer)
 935 {
 936         const struct iio_chan_spec *ch;
 937         int ret, in_ind = -1, out_ind, length;
 938         unsigned in_loc = 0, out_loc = 0;
 939         struct iio_demux_table *p;
 940
 941         /* Clear out any old demux */
 942         iio_buffer_demux_free(buffer);
 943         kfree(buffer->demux_bounce);
 944         buffer->demux_bounce = NULL;
 945
 946         /* First work out which scan mode we will actually have */
 947         if (bitmap_equal(indio_dev->active_scan_mask,
 948                          buffer->scan_mask,
 949                          indio_dev->masklength))
 950                 return 0;
 951
 952         /* Now we have the two masks, work from least sig and build up sizes */
 953         for_each_set_bit(out_ind,
 954                          indio_dev->active_scan_mask,
 955                          indio_dev->masklength) {
 956                 in_ind = find_next_bit(indio_dev->active_scan_mask,
 957                                        indio_dev->masklength,
 958                                        in_ind + 1);
 959                 while (in_ind != out_ind) {
 960                         in_ind = find_next_bit(indio_dev->active_scan_mask,
 961                                                indio_dev->masklength,
 962                                                in_ind + 1);
 963                         ch = iio_find_channel_from_si(indio_dev, in_ind);
 964                         length = ch->scan_type.storagebits/8;
 965                         /* Make sure we are aligned */
 966                         in_loc += length;
 967                         if (in_loc % length)
 968                                 in_loc += length - in_loc % length;
 969                 }
 970                 p = kmalloc(sizeof(*p), GFP_KERNEL);
 971                 if (p == NULL) {
 972                         ret = -ENOMEM;
 973                         goto error_clear_mux_table;
 974                 }
 975                 ch = iio_find_channel_from_si(indio_dev, in_ind);
 976                 length = ch->scan_type.storagebits/8;
 977                 if (out_loc % length)
 978                         out_loc += length - out_loc % length;
 979                 if (in_loc % length)
 980                         in_loc += length - in_loc % length;
 981                 p->from = in_loc;
 982                 p->to = out_loc;
 983                 p->length = length;
 984                 list_add_tail(&p->l, &buffer->demux_list);
 985                 out_loc += length;
 986                 in_loc += length;
 987         }
 988         /* Relies on scan_timestamp being last */
 989         if (buffer->scan_timestamp) {
 990                 p = kmalloc(sizeof(*p), GFP_KERNEL);
 991                 if (p == NULL) {
 992                         ret = -ENOMEM;
 993                         goto error_clear_mux_table;
 994                 }
 995                 ch = iio_find_channel_from_si(indio_dev,
 996                         indio_dev->scan_index_timestamp);
 997                 length = ch->scan_type.storagebits/8;
 998                 if (out_loc % length)
 999                         out_loc += length - out_loc % length;
1000                 if (in_loc % length)
1001                         in_loc += length - in_loc % length;
1002                 p->from = in_loc;
1003                 p->to = out_loc;
1004                 p->length = length;
1005                 list_add_tail(&p->l, &buffer->demux_list);
1006                 out_loc += length;
1007                 in_loc += length;
1008         }
1009         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
1010         if (buffer->demux_bounce == NULL) {
1011                 ret = -ENOMEM;
1012                 goto error_clear_mux_table;
1013         }
1014         return 0;
1015
1016 error_clear_mux_table:
1017         iio_buffer_demux_free(buffer);
1018
1019         return ret;
1020 }
1021
1022 int iio_update_demux(struct iio_dev *indio_dev)
1023 {
1024         struct iio_buffer *buffer;
1025         int ret;
1026
1027         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1028                 ret = iio_buffer_update_demux(indio_dev, buffer);
1029                 if (ret < 0)
1030                         goto error_clear_mux_table;
1031         }
1032         return 0;
1033
1034 error_clear_mux_table:
1035         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
1036                 iio_buffer_demux_free(buffer);
1037
1038         return ret;
1039 }
1040 EXPORT_SYMBOL_GPL(iio_update_demux);
1041
1042 /**
1043  * iio_buffer_release() - Free a buffer's resources
1044  * @ref: Pointer to the kref embedded in the iio_buffer struct
1045  *
1046  * This function is called when the last reference to the buffer has been
1047  * dropped. It will typically free all resources allocated by the buffer. Do not
1048  * call this function manually, always use iio_buffer_put() when done using a
1049  * buffer.
1050  */
1051 static void iio_buffer_release(struct kref *ref)
1052 {
1053         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1054
1055         buffer->access->release(buffer);
1056 }
1057
1058 /**
1059  * iio_buffer_get() - Grab a reference to the buffer
1060  * @buffer: The buffer to grab a reference for, may be NULL
1061  *
1062  * Returns the pointer to the buffer that was passed into the function.
1063  */
1064 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1065 {
1066         if (buffer)
1067                 kref_get(&buffer->ref);
1068
1069         return buffer;
1070 }
1071 EXPORT_SYMBOL_GPL(iio_buffer_get);
1072
1073 /**
1074  * iio_buffer_put() - Release the reference to the buffer
1075  * @buffer: The buffer to release the reference for, may be NULL
1076  */
1077 void iio_buffer_put(struct iio_buffer *buffer)
1078 {
1079         if (buffer)
1080                 kref_put(&buffer->ref, iio_buffer_release);
1081 }
1082 EXPORT_SYMBOL_GPL(iio_buffer_put);