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