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         if (this_attr->c->scan_type.repeat > 1)
 154                 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
 155                        iio_endian_prefix[type],
 156                        this_attr->c->scan_type.sign,
 157                        this_attr->c->scan_type.realbits,
 158                        this_attr->c->scan_type.storagebits,
 159                        this_attr->c->scan_type.repeat,
 160                        this_attr->c->scan_type.shift);
 161                 else
 162                         return sprintf(buf, "%s:%c%d/%d>>%u\n",
 163                        iio_endian_prefix[type],
 164                        this_attr->c->scan_type.sign,
 165                        this_attr->c->scan_type.realbits,
 166                        this_attr->c->scan_type.storagebits,
 167                        this_attr->c->scan_type.shift);
 168 }
 169
 170 static ssize_t iio_scan_el_show(struct device *dev,
 171                                 struct device_attribute *attr,
 172                                 char *buf)
 173 {
 174         int ret;
 175         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 176
 177         /* Ensure ret is 0 or 1. */
 178         ret = !!test_bit(to_iio_dev_attr(attr)->address,
 179                        indio_dev->buffer->scan_mask);
 180
 181         return sprintf(buf, "%d\n", ret);
 182 }
 183
 184 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 185 {
 186         clear_bit(bit, buffer->scan_mask);
 187         return 0;
 188 }
 189
 190 static ssize_t iio_scan_el_store(struct device *dev,
 191                                  struct device_attribute *attr,
 192                                  const char *buf,
 193                                  size_t len)
 194 {
 195         int ret;
 196         bool state;
 197         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 198         struct iio_buffer *buffer = indio_dev->buffer;
 199         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 200
 201         ret = strtobool(buf, &state);
 202         if (ret < 0)
 203                 return ret;
 204         mutex_lock(&indio_dev->mlock);
 205         if (iio_buffer_is_active(indio_dev->buffer)) {
 206                 ret = -EBUSY;
 207                 goto error_ret;
 208         }
 209         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 210         if (ret < 0)
 211                 goto error_ret;
 212         if (!state && ret) {
 213                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 214                 if (ret)
 215                         goto error_ret;
 216         } else if (state && !ret) {
 217                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 218                 if (ret)
 219                         goto error_ret;
 220         }
 221
 222 error_ret:
 223         mutex_unlock(&indio_dev->mlock);
 224
 225         return ret < 0 ? ret : len;
 226
 227 }
 228
 229 static ssize_t iio_scan_el_ts_show(struct device *dev,
 230                                    struct device_attribute *attr,
 231                                    char *buf)
 232 {
 233         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 234         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 235 }
 236
 237 static ssize_t iio_scan_el_ts_store(struct device *dev,
 238                                     struct device_attribute *attr,
 239                                     const char *buf,
 240                                     size_t len)
 241 {
 242         int ret;
 243         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 244         bool state;
 245
 246         ret = strtobool(buf, &state);
 247         if (ret < 0)
 248                 return ret;
 249
 250         mutex_lock(&indio_dev->mlock);
 251         if (iio_buffer_is_active(indio_dev->buffer)) {
 252                 ret = -EBUSY;
 253                 goto error_ret;
 254         }
 255         indio_dev->buffer->scan_timestamp = state;
 256 error_ret:
 257         mutex_unlock(&indio_dev->mlock);
 258
 259         return ret ? ret : len;
 260 }
 261
 262 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 263                                         const struct iio_chan_spec *chan)
 264 {
 265         int ret, attrcount = 0;
 266         struct iio_buffer *buffer = indio_dev->buffer;
 267
 268         ret = __iio_add_chan_devattr("index",
 269                                      chan,
 270                                      &iio_show_scan_index,
 271                                      NULL,
 272                                      0,
 273                                      IIO_SEPARATE,
 274                                      &indio_dev->dev,
 275                                      &buffer->scan_el_dev_attr_list);
 276         if (ret)
 277                 return ret;
 278         attrcount++;
 279         ret = __iio_add_chan_devattr("type",
 280                                      chan,
 281                                      &iio_show_fixed_type,
 282                                      NULL,
 283                                      0,
 284                                      0,
 285                                      &indio_dev->dev,
 286                                      &buffer->scan_el_dev_attr_list);
 287         if (ret)
 288                 return ret;
 289         attrcount++;
 290         if (chan->type != IIO_TIMESTAMP)
 291                 ret = __iio_add_chan_devattr("en",
 292                                              chan,
 293                                              &iio_scan_el_show,
 294                                              &iio_scan_el_store,
 295                                              chan->scan_index,
 296                                              0,
 297                                              &indio_dev->dev,
 298                                              &buffer->scan_el_dev_attr_list);
 299         else
 300                 ret = __iio_add_chan_devattr("en",
 301                                              chan,
 302                                              &iio_scan_el_ts_show,
 303                                              &iio_scan_el_ts_store,
 304                                              chan->scan_index,
 305                                              0,
 306                                              &indio_dev->dev,
 307                                              &buffer->scan_el_dev_attr_list);
 308         if (ret)
 309                 return ret;
 310         attrcount++;
 311         ret = attrcount;
 312         return ret;
 313 }
 314
 315 static const char * const iio_scan_elements_group_name = "scan_elements";
 316
 317 int iio_buffer_register(struct iio_dev *indio_dev,
 318                         const struct iio_chan_spec *channels,
 319                         int num_channels)
 320 {
 321         struct iio_dev_attr *p;
 322         struct attribute **attr;
 323         struct iio_buffer *buffer = indio_dev->buffer;
 324         int ret, i, attrn, attrcount, attrcount_orig = 0;
 325
 326         if (buffer->attrs)
 327                 indio_dev->groups[indio_dev->groupcounter++] = buffer->attrs;
 328
 329         if (buffer->scan_el_attrs != NULL) {
 330                 attr = buffer->scan_el_attrs->attrs;
 331                 while (*attr++ != NULL)
 332                         attrcount_orig++;
 333         }
 334         attrcount = attrcount_orig;
 335         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
 336         if (channels) {
 337                 /* new magic */
 338                 for (i = 0; i < num_channels; i++) {
 339                         if (channels[i].scan_index < 0)
 340                                 continue;
 341
 342                         /* Establish necessary mask length */
 343                         if (channels[i].scan_index >
 344                             (int)indio_dev->masklength - 1)
 345                                 indio_dev->masklength
 346                                         = channels[i].scan_index + 1;
 347
 348                         ret = iio_buffer_add_channel_sysfs(indio_dev,
 349                                                          &channels[i]);
 350                         if (ret < 0)
 351                                 goto error_cleanup_dynamic;
 352                         attrcount += ret;
 353                         if (channels[i].type == IIO_TIMESTAMP)
 354                                 indio_dev->scan_index_timestamp =
 355                                         channels[i].scan_index;
 356                 }
 357                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
 358                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 359                                                     sizeof(*buffer->scan_mask),
 360                                                     GFP_KERNEL);
 361                         if (buffer->scan_mask == NULL) {
 362                                 ret = -ENOMEM;
 363                                 goto error_cleanup_dynamic;
 364                         }
 365                 }
 366         }
 367
 368         buffer->scan_el_group.name = iio_scan_elements_group_name;
 369
 370         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
 371                                               sizeof(buffer->scan_el_group.attrs[0]),
 372                                               GFP_KERNEL);
 373         if (buffer->scan_el_group.attrs == NULL) {
 374                 ret = -ENOMEM;
 375                 goto error_free_scan_mask;
 376         }
 377         if (buffer->scan_el_attrs)
 378                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
 379                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
 380         attrn = attrcount_orig;
 381
 382         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
 383                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
 384         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
 385
 386         return 0;
 387
 388 error_free_scan_mask:
 389         kfree(buffer->scan_mask);
 390 error_cleanup_dynamic:
 391         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
 392
 393         return ret;
 394 }
 395 EXPORT_SYMBOL(iio_buffer_register);
 396
 397 void iio_buffer_unregister(struct iio_dev *indio_dev)
 398 {
 399         kfree(indio_dev->buffer->scan_mask);
 400         kfree(indio_dev->buffer->scan_el_group.attrs);
 401         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
 402 }
 403 EXPORT_SYMBOL(iio_buffer_unregister);
 404
 405 ssize_t iio_buffer_read_length(struct device *dev,
 406                                struct device_attribute *attr,
 407                                char *buf)
 408 {
 409         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 410         struct iio_buffer *buffer = indio_dev->buffer;
 411
 412         if (buffer->access->get_length)
 413                 return sprintf(buf, "%d\n",
 414                                buffer->access->get_length(buffer));
 415
 416         return 0;
 417 }
 418 EXPORT_SYMBOL(iio_buffer_read_length);
 419
 420 ssize_t iio_buffer_write_length(struct device *dev,
 421                                 struct device_attribute *attr,
 422                                 const char *buf,
 423                                 size_t len)
 424 {
 425         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 426         struct iio_buffer *buffer = indio_dev->buffer;
 427         unsigned int val;
 428         int ret;
 429
 430         ret = kstrtouint(buf, 10, &val);
 431         if (ret)
 432                 return ret;
 433
 434         if (buffer->access->get_length)
 435                 if (val == buffer->access->get_length(buffer))
 436                         return len;
 437
 438         mutex_lock(&indio_dev->mlock);
 439         if (iio_buffer_is_active(indio_dev->buffer)) {
 440                 ret = -EBUSY;
 441         } else {
 442                 if (buffer->access->set_length)
 443                         buffer->access->set_length(buffer, val);
 444                 ret = 0;
 445         }
 446         mutex_unlock(&indio_dev->mlock);
 447
 448         return ret ? ret : len;
 449 }
 450 EXPORT_SYMBOL(iio_buffer_write_length);
 451
 452 ssize_t iio_buffer_show_enable(struct device *dev,
 453                                struct device_attribute *attr,
 454                                char *buf)
 455 {
 456         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 457         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 458 }
 459 EXPORT_SYMBOL(iio_buffer_show_enable);
 460
 461 /* Note NULL used as error indicator as it doesn't make sense. */
 462 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
 463                                           unsigned int masklength,
 464                                           const unsigned long *mask)
 465 {
 466         if (bitmap_empty(mask, masklength))
 467                 return NULL;
 468         while (*av_masks) {
 469                 if (bitmap_subset(mask, av_masks, masklength))
 470                         return av_masks;
 471                 av_masks += BITS_TO_LONGS(masklength);
 472         }
 473         return NULL;
 474 }
 475
 476 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 477                                 const unsigned long *mask, bool timestamp)
 478 {
 479         const struct iio_chan_spec *ch;
 480         unsigned bytes = 0;
 481         int length, i;
 482
 483         /* How much space will the demuxed element take? */
 484         for_each_set_bit(i, mask,
 485                          indio_dev->masklength) {
 486                 ch = iio_find_channel_from_si(indio_dev, i);
 487                 if (ch->scan_type.repeat > 1)
 488                         length = ch->scan_type.storagebits / 8 *
 489                                 ch->scan_type.repeat;
 490                 else
 491                         length = ch->scan_type.storagebits / 8;
 492                 bytes = ALIGN(bytes, length);
 493                 bytes += length;
 494         }
 495         if (timestamp) {
 496                 ch = iio_find_channel_from_si(indio_dev,
 497                                               indio_dev->scan_index_timestamp);
 498                 if (ch->scan_type.repeat > 1)
 499                         length = ch->scan_type.storagebits / 8 *
 500                                 ch->scan_type.repeat;
 501                 else
 502                         length = ch->scan_type.storagebits / 8;
 503                 bytes = ALIGN(bytes, length);
 504                 bytes += length;
 505         }
 506         return bytes;
 507 }
 508
 509 static void iio_buffer_activate(struct iio_dev *indio_dev,
 510         struct iio_buffer *buffer)
 511 {
 512         iio_buffer_get(buffer);
 513         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 514 }
 515
 516 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 517 {
 518         list_del_init(&buffer->buffer_list);
 519         iio_buffer_put(buffer);
 520 }
 521
 522 void iio_disable_all_buffers(struct iio_dev *indio_dev)
 523 {
 524         struct iio_buffer *buffer, *_buffer;
 525
 526         if (list_empty(&indio_dev->buffer_list))
 527                 return;
 528
 529         if (indio_dev->setup_ops->predisable)
 530                 indio_dev->setup_ops->predisable(indio_dev);
 531
 532         list_for_each_entry_safe(buffer, _buffer,
 533                         &indio_dev->buffer_list, buffer_list)
 534                 iio_buffer_deactivate(buffer);
 535
 536         indio_dev->currentmode = INDIO_DIRECT_MODE;
 537         if (indio_dev->setup_ops->postdisable)
 538                 indio_dev->setup_ops->postdisable(indio_dev);
 539
 540         if (indio_dev->available_scan_masks == NULL)
 541                 kfree(indio_dev->active_scan_mask);
 542 }
 543
 544 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 545         struct iio_buffer *buffer)
 546 {
 547         unsigned int bytes;
 548
 549         if (!buffer->access->set_bytes_per_datum)
 550                 return;
 551
 552         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 553                 buffer->scan_timestamp);
 554
 555         buffer->access->set_bytes_per_datum(buffer, bytes);
 556 }
 557
 558 static int __iio_update_buffers(struct iio_dev *indio_dev,
 559                        struct iio_buffer *insert_buffer,
 560                        struct iio_buffer *remove_buffer)
 561 {
 562         int ret;
 563         int success = 0;
 564         struct iio_buffer *buffer;
 565         unsigned long *compound_mask;
 566         const unsigned long *old_mask;
 567
 568         /* Wind down existing buffers - iff there are any */
 569         if (!list_empty(&indio_dev->buffer_list)) {
 570                 if (indio_dev->setup_ops->predisable) {
 571                         ret = indio_dev->setup_ops->predisable(indio_dev);
 572                         if (ret)
 573                                 return ret;
 574                 }
 575                 indio_dev->currentmode = INDIO_DIRECT_MODE;
 576                 if (indio_dev->setup_ops->postdisable) {
 577                         ret = indio_dev->setup_ops->postdisable(indio_dev);
 578                         if (ret)
 579                                 return ret;
 580                 }
 581         }
 582         /* Keep a copy of current setup to allow roll back */
 583         old_mask = indio_dev->active_scan_mask;
 584         if (!indio_dev->available_scan_masks)
 585                 indio_dev->active_scan_mask = NULL;
 586
 587         if (remove_buffer)
 588                 iio_buffer_deactivate(remove_buffer);
 589         if (insert_buffer)
 590                 iio_buffer_activate(indio_dev, insert_buffer);
 591
 592         /* If no buffers in list, we are done */
 593         if (list_empty(&indio_dev->buffer_list)) {
 594                 indio_dev->currentmode = INDIO_DIRECT_MODE;
 595                 if (indio_dev->available_scan_masks == NULL)
 596                         kfree(old_mask);
 597                 return 0;
 598         }
 599
 600         /* What scan mask do we actually have? */
 601         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 602                                 sizeof(long), GFP_KERNEL);
 603         if (compound_mask == NULL) {
 604                 if (indio_dev->available_scan_masks == NULL)
 605                         kfree(old_mask);
 606                 return -ENOMEM;
 607         }
 608         indio_dev->scan_timestamp = 0;
 609
 610         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 611                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 612                           indio_dev->masklength);
 613                 indio_dev->scan_timestamp |= buffer->scan_timestamp;
 614         }
 615         if (indio_dev->available_scan_masks) {
 616                 indio_dev->active_scan_mask =
 617                         iio_scan_mask_match(indio_dev->available_scan_masks,
 618                                             indio_dev->masklength,
 619                                             compound_mask);
 620                 if (indio_dev->active_scan_mask == NULL) {
 621                         /*
 622                          * Roll back.
 623                          * Note can only occur when adding a buffer.
 624                          */
 625                         iio_buffer_deactivate(insert_buffer);
 626                         if (old_mask) {
 627                                 indio_dev->active_scan_mask = old_mask;
 628                                 success = -EINVAL;
 629                         }
 630                         else {
 631                                 kfree(compound_mask);
 632                                 ret = -EINVAL;
 633                                 return ret;
 634                         }
 635                 }
 636         } else {
 637                 indio_dev->active_scan_mask = compound_mask;
 638         }
 639
 640         iio_update_demux(indio_dev);
 641
 642         /* Wind up again */
 643         if (indio_dev->setup_ops->preenable) {
 644                 ret = indio_dev->setup_ops->preenable(indio_dev);
 645                 if (ret) {
 646                         printk(KERN_ERR
 647                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 648                         goto error_remove_inserted;
 649                 }
 650         }
 651         indio_dev->scan_bytes =
 652                 iio_compute_scan_bytes(indio_dev,
 653                                        indio_dev->active_scan_mask,
 654                                        indio_dev->scan_timestamp);
 655         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 656                 iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 657                 if (buffer->access->request_update) {
 658                         ret = buffer->access->request_update(buffer);
 659                         if (ret) {
 660                                 printk(KERN_INFO
 661                                        "Buffer not started: buffer parameter update failed (%d)\n", ret);
 662                                 goto error_run_postdisable;
 663                         }
 664                 }
 665         }
 666         if (indio_dev->info->update_scan_mode) {
 667                 ret = indio_dev->info
 668                         ->update_scan_mode(indio_dev,
 669                                            indio_dev->active_scan_mask);
 670                 if (ret < 0) {
 671                         printk(KERN_INFO "Buffer not started: update scan mode failed (%d)\n", ret);
 672                         goto error_run_postdisable;
 673                 }
 674         }
 675         /* Definitely possible for devices to support both of these. */
 676         if (indio_dev->modes & INDIO_BUFFER_TRIGGERED) {
 677                 if (!indio_dev->trig) {
 678                         printk(KERN_INFO "Buffer not started: no trigger\n");
 679                         ret = -EINVAL;
 680                         /* Can only occur on first buffer */
 681                         goto error_run_postdisable;
 682                 }
 683                 indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
 684         } else if (indio_dev->modes & INDIO_BUFFER_HARDWARE) {
 685                 indio_dev->currentmode = INDIO_BUFFER_HARDWARE;
 686         } else { /* Should never be reached */
 687                 ret = -EINVAL;
 688                 goto error_run_postdisable;
 689         }
 690
 691         if (indio_dev->setup_ops->postenable) {
 692                 ret = indio_dev->setup_ops->postenable(indio_dev);
 693                 if (ret) {
 694                         printk(KERN_INFO
 695                                "Buffer not started: postenable failed (%d)\n", ret);
 696                         indio_dev->currentmode = INDIO_DIRECT_MODE;
 697                         if (indio_dev->setup_ops->postdisable)
 698                                 indio_dev->setup_ops->postdisable(indio_dev);
 699                         goto error_disable_all_buffers;
 700                 }
 701         }
 702
 703         if (indio_dev->available_scan_masks)
 704                 kfree(compound_mask);
 705         else
 706                 kfree(old_mask);
 707
 708         return success;
 709
 710 error_disable_all_buffers:
 711         indio_dev->currentmode = INDIO_DIRECT_MODE;
 712 error_run_postdisable:
 713         if (indio_dev->setup_ops->postdisable)
 714                 indio_dev->setup_ops->postdisable(indio_dev);
 715 error_remove_inserted:
 716         if (insert_buffer)
 717                 iio_buffer_deactivate(insert_buffer);
 718         indio_dev->active_scan_mask = old_mask;
 719         kfree(compound_mask);
 720         return ret;
 721 }
 722
 723 int iio_update_buffers(struct iio_dev *indio_dev,
 724                        struct iio_buffer *insert_buffer,
 725                        struct iio_buffer *remove_buffer)
 726 {
 727         int ret;
 728
 729         if (insert_buffer == remove_buffer)
 730                 return 0;
 731
 732         mutex_lock(&indio_dev->info_exist_lock);
 733         mutex_lock(&indio_dev->mlock);
 734
 735         if (insert_buffer && iio_buffer_is_active(insert_buffer))
 736                 insert_buffer = NULL;
 737
 738         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
 739                 remove_buffer = NULL;
 740
 741         if (!insert_buffer && !remove_buffer) {
 742                 ret = 0;
 743                 goto out_unlock;
 744         }
 745
 746         if (indio_dev->info == NULL) {
 747                 ret = -ENODEV;
 748                 goto out_unlock;
 749         }
 750
 751         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 752
 753 out_unlock:
 754         mutex_unlock(&indio_dev->mlock);
 755         mutex_unlock(&indio_dev->info_exist_lock);
 756
 757         return ret;
 758 }
 759 EXPORT_SYMBOL_GPL(iio_update_buffers);
 760
 761 ssize_t iio_buffer_store_enable(struct device *dev,
 762                                 struct device_attribute *attr,
 763                                 const char *buf,
 764                                 size_t len)
 765 {
 766         int ret;
 767         bool requested_state;
 768         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 769         bool inlist;
 770
 771         ret = strtobool(buf, &requested_state);
 772         if (ret < 0)
 773                 return ret;
 774
 775         mutex_lock(&indio_dev->mlock);
 776
 777         /* Find out if it is in the list */
 778         inlist = iio_buffer_is_active(indio_dev->buffer);
 779         /* Already in desired state */
 780         if (inlist == requested_state)
 781                 goto done;
 782
 783         if (requested_state)
 784                 ret = __iio_update_buffers(indio_dev,
 785                                          indio_dev->buffer, NULL);
 786         else
 787                 ret = __iio_update_buffers(indio_dev,
 788                                          NULL, indio_dev->buffer);
 789
 790         if (ret < 0)
 791                 goto done;
 792 done:
 793         mutex_unlock(&indio_dev->mlock);
 794         return (ret < 0) ? ret : len;
 795 }
 796 EXPORT_SYMBOL(iio_buffer_store_enable);
 797
 798 /**
 799  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
 800  * @indio_dev: the iio device
 801  * @mask: scan mask to be checked
 802  *
 803  * Return true if exactly one bit is set in the scan mask, false otherwise. It
 804  * can be used for devices where only one channel can be active for sampling at
 805  * a time.
 806  */
 807 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 808         const unsigned long *mask)
 809 {
 810         return bitmap_weight(mask, indio_dev->masklength) == 1;
 811 }
 812 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
 813
 814 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
 815         const unsigned long *mask)
 816 {
 817         if (!indio_dev->setup_ops->validate_scan_mask)
 818                 return true;
 819
 820         return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
 821 }
 822
 823 /**
 824  * iio_scan_mask_set() - set particular bit in the scan mask
 825  * @indio_dev: the iio device
 826  * @buffer: the buffer whose scan mask we are interested in
 827  * @bit: the bit to be set.
 828  *
 829  * Note that at this point we have no way of knowing what other
 830  * buffers might request, hence this code only verifies that the
 831  * individual buffers request is plausible.
 832  */
 833 int iio_scan_mask_set(struct iio_dev *indio_dev,
 834                       struct iio_buffer *buffer, int bit)
 835 {
 836         const unsigned long *mask;
 837         unsigned long *trialmask;
 838
 839         trialmask = kmalloc(sizeof(*trialmask)*
 840                             BITS_TO_LONGS(indio_dev->masklength),
 841                             GFP_KERNEL);
 842
 843         if (trialmask == NULL)
 844                 return -ENOMEM;
 845         if (!indio_dev->masklength) {
 846                 WARN_ON("Trying to set scanmask prior to registering buffer\n");
 847                 goto err_invalid_mask;
 848         }
 849         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 850         set_bit(bit, trialmask);
 851
 852         if (!iio_validate_scan_mask(indio_dev, trialmask))
 853                 goto err_invalid_mask;
 854
 855         if (indio_dev->available_scan_masks) {
 856                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 857                                            indio_dev->masklength,
 858                                            trialmask);
 859                 if (!mask)
 860                         goto err_invalid_mask;
 861         }
 862         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 863
 864         kfree(trialmask);
 865
 866         return 0;
 867
 868 err_invalid_mask:
 869         kfree(trialmask);
 870         return -EINVAL;
 871 }
 872 EXPORT_SYMBOL_GPL(iio_scan_mask_set);
 873
 874 int iio_scan_mask_query(struct iio_dev *indio_dev,
 875                         struct iio_buffer *buffer, int bit)
 876 {
 877         if (bit > indio_dev->masklength)
 878                 return -EINVAL;
 879
 880         if (!buffer->scan_mask)
 881                 return 0;
 882
 883         /* Ensure return value is 0 or 1. */
 884         return !!test_bit(bit, buffer->scan_mask);
 885 };
 886 EXPORT_SYMBOL_GPL(iio_scan_mask_query);
 887
 888 /**
 889  * struct iio_demux_table() - table describing demux memcpy ops
 890  * @from:       index to copy from
 891  * @to:         index to copy to
 892  * @length:     how many bytes to copy
 893  * @l:          list head used for management
 894  */
 895 struct iio_demux_table {
 896         unsigned from;
 897         unsigned to;
 898         unsigned length;
 899         struct list_head l;
 900 };
 901
 902 static const void *iio_demux(struct iio_buffer *buffer,
 903                                  const void *datain)
 904 {
 905         struct iio_demux_table *t;
 906
 907         if (list_empty(&buffer->demux_list))
 908                 return datain;
 909         list_for_each_entry(t, &buffer->demux_list, l)
 910                 memcpy(buffer->demux_bounce + t->to,
 911                        datain + t->from, t->length);
 912
 913         return buffer->demux_bounce;
 914 }
 915
 916 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
 917 {
 918         const void *dataout = iio_demux(buffer, data);
 919
 920         return buffer->access->store_to(buffer, dataout);
 921 }
 922
 923 static void iio_buffer_demux_free(struct iio_buffer *buffer)
 924 {
 925         struct iio_demux_table *p, *q;
 926         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
 927                 list_del(&p->l);
 928                 kfree(p);
 929         }
 930 }
 931
 932
 933 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
 934 {
 935         int ret;
 936         struct iio_buffer *buf;
 937
 938         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
 939                 ret = iio_push_to_buffer(buf, data);
 940                 if (ret < 0)
 941                         return ret;
 942         }
 943
 944         return 0;
 945 }
 946 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
 947
 948 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
 949                                    struct iio_buffer *buffer)
 950 {
 951         const struct iio_chan_spec *ch;
 952         int ret, in_ind = -1, out_ind, length;
 953         unsigned in_loc = 0, out_loc = 0;
 954         struct iio_demux_table *p;
 955
 956         /* Clear out any old demux */
 957         iio_buffer_demux_free(buffer);
 958         kfree(buffer->demux_bounce);
 959         buffer->demux_bounce = NULL;
 960
 961         /* First work out which scan mode we will actually have */
 962         if (bitmap_equal(indio_dev->active_scan_mask,
 963                          buffer->scan_mask,
 964                          indio_dev->masklength))
 965                 return 0;
 966
 967         /* Now we have the two masks, work from least sig and build up sizes */
 968         for_each_set_bit(out_ind,
 969                          indio_dev->active_scan_mask,
 970                          indio_dev->masklength) {
 971                 in_ind = find_next_bit(indio_dev->active_scan_mask,
 972                                        indio_dev->masklength,
 973                                        in_ind + 1);
 974                 while (in_ind != out_ind) {
 975                         in_ind = find_next_bit(indio_dev->active_scan_mask,
 976                                                indio_dev->masklength,
 977                                                in_ind + 1);
 978                         ch = iio_find_channel_from_si(indio_dev, in_ind);
 979                         if (ch->scan_type.repeat > 1)
 980                                 length = ch->scan_type.storagebits / 8 *
 981                                         ch->scan_type.repeat;
 982                         else
 983                                 length = ch->scan_type.storagebits / 8;
 984                         /* Make sure we are aligned */
 985                         in_loc += length;
 986                         if (in_loc % length)
 987                                 in_loc += length - in_loc % length;
 988                 }
 989                 p = kmalloc(sizeof(*p), GFP_KERNEL);
 990                 if (p == NULL) {
 991                         ret = -ENOMEM;
 992                         goto error_clear_mux_table;
 993                 }
 994                 ch = iio_find_channel_from_si(indio_dev, in_ind);
 995                 if (ch->scan_type.repeat > 1)
 996                         length = ch->scan_type.storagebits / 8 *
 997                                 ch->scan_type.repeat;
 998                 else
 999                         length = ch->scan_type.storagebits / 8;
1000                 if (out_loc % length)
1001                         out_loc += length - out_loc % length;
1002                 if (in_loc % length)
1003                         in_loc += length - in_loc % length;
1004                 p->from = in_loc;
1005                 p->to = out_loc;
1006                 p->length = length;
1007                 list_add_tail(&p->l, &buffer->demux_list);
1008                 out_loc += length;
1009                 in_loc += length;
1010         }
1011         /* Relies on scan_timestamp being last */
1012         if (buffer->scan_timestamp) {
1013                 p = kmalloc(sizeof(*p), GFP_KERNEL);
1014                 if (p == NULL) {
1015                         ret = -ENOMEM;
1016                         goto error_clear_mux_table;
1017                 }
1018                 ch = iio_find_channel_from_si(indio_dev,
1019                         indio_dev->scan_index_timestamp);
1020                 if (ch->scan_type.repeat > 1)
1021                         length = ch->scan_type.storagebits / 8 *
1022                                 ch->scan_type.repeat;
1023                 else
1024                         length = ch->scan_type.storagebits / 8;
1025                 if (out_loc % length)
1026                         out_loc += length - out_loc % length;
1027                 if (in_loc % length)
1028                         in_loc += length - in_loc % length;
1029                 p->from = in_loc;
1030                 p->to = out_loc;
1031                 p->length = length;
1032                 list_add_tail(&p->l, &buffer->demux_list);
1033                 out_loc += length;
1034                 in_loc += length;
1035         }
1036         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
1037         if (buffer->demux_bounce == NULL) {
1038                 ret = -ENOMEM;
1039                 goto error_clear_mux_table;
1040         }
1041         return 0;
1042
1043 error_clear_mux_table:
1044         iio_buffer_demux_free(buffer);
1045
1046         return ret;
1047 }
1048
1049 int iio_update_demux(struct iio_dev *indio_dev)
1050 {
1051         struct iio_buffer *buffer;
1052         int ret;
1053
1054         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1055                 ret = iio_buffer_update_demux(indio_dev, buffer);
1056                 if (ret < 0)
1057                         goto error_clear_mux_table;
1058         }
1059         return 0;
1060
1061 error_clear_mux_table:
1062         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
1063                 iio_buffer_demux_free(buffer);
1064
1065         return ret;
1066 }
1067 EXPORT_SYMBOL_GPL(iio_update_demux);
1068
1069 /**
1070  * iio_buffer_release() - Free a buffer's resources
1071  * @ref: Pointer to the kref embedded in the iio_buffer struct
1072  *
1073  * This function is called when the last reference to the buffer has been
1074  * dropped. It will typically free all resources allocated by the buffer. Do not
1075  * call this function manually, always use iio_buffer_put() when done using a
1076  * buffer.
1077  */
1078 static void iio_buffer_release(struct kref *ref)
1079 {
1080         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1081
1082         buffer->access->release(buffer);
1083 }
1084
1085 /**
1086  * iio_buffer_get() - Grab a reference to the buffer
1087  * @buffer: The buffer to grab a reference for, may be NULL
1088  *
1089  * Returns the pointer to the buffer that was passed into the function.
1090  */
1091 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1092 {
1093         if (buffer)
1094                 kref_get(&buffer->ref);
1095
1096         return buffer;
1097 }
1098 EXPORT_SYMBOL_GPL(iio_buffer_get);
1099
1100 /**
1101  * iio_buffer_put() - Release the reference to the buffer
1102  * @buffer: The buffer to release the reference for, may be NULL
1103  */
1104 void iio_buffer_put(struct iio_buffer *buffer)
1105 {
1106         if (buffer)
1107                 kref_put(&buffer->ref, iio_buffer_release);
1108 }
1109 EXPORT_SYMBOL_GPL(iio_buffer_put);