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         return buf->access->data_available(buf);
  43 }
  44
  45 /**
  46  * iio_buffer_read_first_n_outer() - chrdev read for buffer access
  47  *
  48  * This function relies on all buffer implementations having an
  49  * iio_buffer as their first element.
  50  **/
  51 ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
  52                                       size_t n, loff_t *f_ps)
  53 {
  54         struct iio_dev *indio_dev = filp->private_data;
  55         struct iio_buffer *rb = indio_dev->buffer;
  56         int ret;
  57
  58         if (!indio_dev->info)
  59                 return -ENODEV;
  60
  61         if (!rb || !rb->access->read_first_n)
  62                 return -EINVAL;
  63
  64         do {
  65                 if (!iio_buffer_data_available(rb)) {
  66                         if (filp->f_flags & O_NONBLOCK)
  67                                 return -EAGAIN;
  68
  69                         ret = wait_event_interruptible(rb->pollq,
  70                                         iio_buffer_data_available(rb) ||
  71                                         indio_dev->info == NULL);
  72                         if (ret)
  73                                 return ret;
  74                         if (indio_dev->info == NULL)
  75                                 return -ENODEV;
  76                 }
  77
  78                 ret = rb->access->read_first_n(rb, n, buf);
  79                 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
  80                         ret = -EAGAIN;
  81          } while (ret == 0);
  82
  83         return ret;
  84 }
  85
  86 /**
  87  * iio_buffer_poll() - poll the buffer to find out if it has data
  88  */
  89 unsigned int iio_buffer_poll(struct file *filp,
  90                              struct poll_table_struct *wait)
  91 {
  92         struct iio_dev *indio_dev = filp->private_data;
  93         struct iio_buffer *rb = indio_dev->buffer;
  94
  95         if (!indio_dev->info)
  96                 return -ENODEV;
  97
  98         poll_wait(filp, &rb->pollq, wait);
  99         if (iio_buffer_data_available(rb))
 100                 return POLLIN | POLLRDNORM;
 101         /* need a way of knowing if there may be enough data... */
 102         return 0;
 103 }
 104
 105 /**
 106  * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
 107  * @indio_dev: The IIO device
 108  *
 109  * Wakes up the event waitqueue used for poll(). Should usually
 110  * be called when the device is unregistered.
 111  */
 112 void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
 113 {
 114         if (!indio_dev->buffer)
 115                 return;
 116
 117         wake_up(&indio_dev->buffer->pollq);
 118 }
 119
 120 void iio_buffer_init(struct iio_buffer *buffer)
 121 {
 122         INIT_LIST_HEAD(&buffer->demux_list);
 123         INIT_LIST_HEAD(&buffer->buffer_list);
 124         init_waitqueue_head(&buffer->pollq);
 125         kref_init(&buffer->ref);
 126 }
 127 EXPORT_SYMBOL(iio_buffer_init);
 128
 129 static ssize_t iio_show_scan_index(struct device *dev,
 130                                    struct device_attribute *attr,
 131                                    char *buf)
 132 {
 133         return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
 134 }
 135
 136 static ssize_t iio_show_fixed_type(struct device *dev,
 137                                    struct device_attribute *attr,
 138                                    char *buf)
 139 {
 140         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 141         u8 type = this_attr->c->scan_type.endianness;
 142
 143         if (type == IIO_CPU) {
 144 #ifdef __LITTLE_ENDIAN
 145                 type = IIO_LE;
 146 #else
 147                 type = IIO_BE;
 148 #endif
 149         }
 150         if (this_attr->c->scan_type.repeat > 1)
 151                 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
 152                        iio_endian_prefix[type],
 153                        this_attr->c->scan_type.sign,
 154                        this_attr->c->scan_type.realbits,
 155                        this_attr->c->scan_type.storagebits,
 156                        this_attr->c->scan_type.repeat,
 157                        this_attr->c->scan_type.shift);
 158                 else
 159                         return sprintf(buf, "%s:%c%d/%d>>%u\n",
 160                        iio_endian_prefix[type],
 161                        this_attr->c->scan_type.sign,
 162                        this_attr->c->scan_type.realbits,
 163                        this_attr->c->scan_type.storagebits,
 164                        this_attr->c->scan_type.shift);
 165 }
 166
 167 static ssize_t iio_scan_el_show(struct device *dev,
 168                                 struct device_attribute *attr,
 169                                 char *buf)
 170 {
 171         int ret;
 172         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 173
 174         /* Ensure ret is 0 or 1. */
 175         ret = !!test_bit(to_iio_dev_attr(attr)->address,
 176                        indio_dev->buffer->scan_mask);
 177
 178         return sprintf(buf, "%d\n", ret);
 179 }
 180
 181 /* Note NULL used as error indicator as it doesn't make sense. */
 182 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
 183                                           unsigned int masklength,
 184                                           const unsigned long *mask)
 185 {
 186         if (bitmap_empty(mask, masklength))
 187                 return NULL;
 188         while (*av_masks) {
 189                 if (bitmap_subset(mask, av_masks, masklength))
 190                         return av_masks;
 191                 av_masks += BITS_TO_LONGS(masklength);
 192         }
 193         return NULL;
 194 }
 195
 196 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
 197         const unsigned long *mask)
 198 {
 199         if (!indio_dev->setup_ops->validate_scan_mask)
 200                 return true;
 201
 202         return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
 203 }
 204
 205 /**
 206  * iio_scan_mask_set() - set particular bit in the scan mask
 207  * @indio_dev: the iio device
 208  * @buffer: the buffer whose scan mask we are interested in
 209  * @bit: the bit to be set.
 210  *
 211  * Note that at this point we have no way of knowing what other
 212  * buffers might request, hence this code only verifies that the
 213  * individual buffers request is plausible.
 214  */
 215 static int iio_scan_mask_set(struct iio_dev *indio_dev,
 216                       struct iio_buffer *buffer, int bit)
 217 {
 218         const unsigned long *mask;
 219         unsigned long *trialmask;
 220
 221         trialmask = kmalloc(sizeof(*trialmask)*
 222                             BITS_TO_LONGS(indio_dev->masklength),
 223                             GFP_KERNEL);
 224
 225         if (trialmask == NULL)
 226                 return -ENOMEM;
 227         if (!indio_dev->masklength) {
 228                 WARN_ON("Trying to set scanmask prior to registering buffer\n");
 229                 goto err_invalid_mask;
 230         }
 231         bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 232         set_bit(bit, trialmask);
 233
 234         if (!iio_validate_scan_mask(indio_dev, trialmask))
 235                 goto err_invalid_mask;
 236
 237         if (indio_dev->available_scan_masks) {
 238                 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
 239                                            indio_dev->masklength,
 240                                            trialmask);
 241                 if (!mask)
 242                         goto err_invalid_mask;
 243         }
 244         bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
 245
 246         kfree(trialmask);
 247
 248         return 0;
 249
 250 err_invalid_mask:
 251         kfree(trialmask);
 252         return -EINVAL;
 253 }
 254
 255 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 256 {
 257         clear_bit(bit, buffer->scan_mask);
 258         return 0;
 259 }
 260
 261 static ssize_t iio_scan_el_store(struct device *dev,
 262                                  struct device_attribute *attr,
 263                                  const char *buf,
 264                                  size_t len)
 265 {
 266         int ret;
 267         bool state;
 268         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 269         struct iio_buffer *buffer = indio_dev->buffer;
 270         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 271
 272         ret = strtobool(buf, &state);
 273         if (ret < 0)
 274                 return ret;
 275         mutex_lock(&indio_dev->mlock);
 276         if (iio_buffer_is_active(indio_dev->buffer)) {
 277                 ret = -EBUSY;
 278                 goto error_ret;
 279         }
 280         ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 281         if (ret < 0)
 282                 goto error_ret;
 283         if (!state && ret) {
 284                 ret = iio_scan_mask_clear(buffer, this_attr->address);
 285                 if (ret)
 286                         goto error_ret;
 287         } else if (state && !ret) {
 288                 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
 289                 if (ret)
 290                         goto error_ret;
 291         }
 292
 293 error_ret:
 294         mutex_unlock(&indio_dev->mlock);
 295
 296         return ret < 0 ? ret : len;
 297
 298 }
 299
 300 static ssize_t iio_scan_el_ts_show(struct device *dev,
 301                                    struct device_attribute *attr,
 302                                    char *buf)
 303 {
 304         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 305         return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
 306 }
 307
 308 static ssize_t iio_scan_el_ts_store(struct device *dev,
 309                                     struct device_attribute *attr,
 310                                     const char *buf,
 311                                     size_t len)
 312 {
 313         int ret;
 314         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 315         bool state;
 316
 317         ret = strtobool(buf, &state);
 318         if (ret < 0)
 319                 return ret;
 320
 321         mutex_lock(&indio_dev->mlock);
 322         if (iio_buffer_is_active(indio_dev->buffer)) {
 323                 ret = -EBUSY;
 324                 goto error_ret;
 325         }
 326         indio_dev->buffer->scan_timestamp = state;
 327 error_ret:
 328         mutex_unlock(&indio_dev->mlock);
 329
 330         return ret ? ret : len;
 331 }
 332
 333 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 334                                         const struct iio_chan_spec *chan)
 335 {
 336         int ret, attrcount = 0;
 337         struct iio_buffer *buffer = indio_dev->buffer;
 338
 339         ret = __iio_add_chan_devattr("index",
 340                                      chan,
 341                                      &iio_show_scan_index,
 342                                      NULL,
 343                                      0,
 344                                      IIO_SEPARATE,
 345                                      &indio_dev->dev,
 346                                      &buffer->scan_el_dev_attr_list);
 347         if (ret)
 348                 return ret;
 349         attrcount++;
 350         ret = __iio_add_chan_devattr("type",
 351                                      chan,
 352                                      &iio_show_fixed_type,
 353                                      NULL,
 354                                      0,
 355                                      0,
 356                                      &indio_dev->dev,
 357                                      &buffer->scan_el_dev_attr_list);
 358         if (ret)
 359                 return ret;
 360         attrcount++;
 361         if (chan->type != IIO_TIMESTAMP)
 362                 ret = __iio_add_chan_devattr("en",
 363                                              chan,
 364                                              &iio_scan_el_show,
 365                                              &iio_scan_el_store,
 366                                              chan->scan_index,
 367                                              0,
 368                                              &indio_dev->dev,
 369                                              &buffer->scan_el_dev_attr_list);
 370         else
 371                 ret = __iio_add_chan_devattr("en",
 372                                              chan,
 373                                              &iio_scan_el_ts_show,
 374                                              &iio_scan_el_ts_store,
 375                                              chan->scan_index,
 376                                              0,
 377                                              &indio_dev->dev,
 378                                              &buffer->scan_el_dev_attr_list);
 379         if (ret)
 380                 return ret;
 381         attrcount++;
 382         ret = attrcount;
 383         return ret;
 384 }
 385
 386 static const char * const iio_scan_elements_group_name = "scan_elements";
 387
 388 int iio_buffer_register(struct iio_dev *indio_dev,
 389                         const struct iio_chan_spec *channels,
 390                         int num_channels)
 391 {
 392         struct iio_dev_attr *p;
 393         struct attribute **attr;
 394         struct iio_buffer *buffer = indio_dev->buffer;
 395         int ret, i, attrn, attrcount, attrcount_orig = 0;
 396
 397         if (buffer->attrs)
 398                 indio_dev->groups[indio_dev->groupcounter++] = buffer->attrs;
 399
 400         if (buffer->scan_el_attrs != NULL) {
 401                 attr = buffer->scan_el_attrs->attrs;
 402                 while (*attr++ != NULL)
 403                         attrcount_orig++;
 404         }
 405         attrcount = attrcount_orig;
 406         INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
 407         if (channels) {
 408                 /* new magic */
 409                 for (i = 0; i < num_channels; i++) {
 410                         if (channels[i].scan_index < 0)
 411                                 continue;
 412
 413                         /* Establish necessary mask length */
 414                         if (channels[i].scan_index >
 415                             (int)indio_dev->masklength - 1)
 416                                 indio_dev->masklength
 417                                         = channels[i].scan_index + 1;
 418
 419                         ret = iio_buffer_add_channel_sysfs(indio_dev,
 420                                                          &channels[i]);
 421                         if (ret < 0)
 422                                 goto error_cleanup_dynamic;
 423                         attrcount += ret;
 424                         if (channels[i].type == IIO_TIMESTAMP)
 425                                 indio_dev->scan_index_timestamp =
 426                                         channels[i].scan_index;
 427                 }
 428                 if (indio_dev->masklength && buffer->scan_mask == NULL) {
 429                         buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 430                                                     sizeof(*buffer->scan_mask),
 431                                                     GFP_KERNEL);
 432                         if (buffer->scan_mask == NULL) {
 433                                 ret = -ENOMEM;
 434                                 goto error_cleanup_dynamic;
 435                         }
 436                 }
 437         }
 438
 439         buffer->scan_el_group.name = iio_scan_elements_group_name;
 440
 441         buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
 442                                               sizeof(buffer->scan_el_group.attrs[0]),
 443                                               GFP_KERNEL);
 444         if (buffer->scan_el_group.attrs == NULL) {
 445                 ret = -ENOMEM;
 446                 goto error_free_scan_mask;
 447         }
 448         if (buffer->scan_el_attrs)
 449                 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
 450                        sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
 451         attrn = attrcount_orig;
 452
 453         list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
 454                 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
 455         indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
 456
 457         return 0;
 458
 459 error_free_scan_mask:
 460         kfree(buffer->scan_mask);
 461 error_cleanup_dynamic:
 462         iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
 463
 464         return ret;
 465 }
 466 EXPORT_SYMBOL(iio_buffer_register);
 467
 468 void iio_buffer_unregister(struct iio_dev *indio_dev)
 469 {
 470         kfree(indio_dev->buffer->scan_mask);
 471         kfree(indio_dev->buffer->scan_el_group.attrs);
 472         iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
 473 }
 474 EXPORT_SYMBOL(iio_buffer_unregister);
 475
 476 ssize_t iio_buffer_read_length(struct device *dev,
 477                                struct device_attribute *attr,
 478                                char *buf)
 479 {
 480         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 481         struct iio_buffer *buffer = indio_dev->buffer;
 482
 483         if (buffer->access->get_length)
 484                 return sprintf(buf, "%d\n",
 485                                buffer->access->get_length(buffer));
 486
 487         return 0;
 488 }
 489 EXPORT_SYMBOL(iio_buffer_read_length);
 490
 491 ssize_t iio_buffer_write_length(struct device *dev,
 492                                 struct device_attribute *attr,
 493                                 const char *buf,
 494                                 size_t len)
 495 {
 496         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 497         struct iio_buffer *buffer = indio_dev->buffer;
 498         unsigned int val;
 499         int ret;
 500
 501         ret = kstrtouint(buf, 10, &val);
 502         if (ret)
 503                 return ret;
 504
 505         if (buffer->access->get_length)
 506                 if (val == buffer->access->get_length(buffer))
 507                         return len;
 508
 509         mutex_lock(&indio_dev->mlock);
 510         if (iio_buffer_is_active(indio_dev->buffer)) {
 511                 ret = -EBUSY;
 512         } else {
 513                 if (buffer->access->set_length)
 514                         buffer->access->set_length(buffer, val);
 515                 ret = 0;
 516         }
 517         mutex_unlock(&indio_dev->mlock);
 518
 519         return ret ? ret : len;
 520 }
 521 EXPORT_SYMBOL(iio_buffer_write_length);
 522
 523 ssize_t iio_buffer_show_enable(struct device *dev,
 524                                struct device_attribute *attr,
 525                                char *buf)
 526 {
 527         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 528         return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
 529 }
 530 EXPORT_SYMBOL(iio_buffer_show_enable);
 531
 532 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
 533                                 const unsigned long *mask, bool timestamp)
 534 {
 535         const struct iio_chan_spec *ch;
 536         unsigned bytes = 0;
 537         int length, i;
 538
 539         /* How much space will the demuxed element take? */
 540         for_each_set_bit(i, mask,
 541                          indio_dev->masklength) {
 542                 ch = iio_find_channel_from_si(indio_dev, i);
 543                 if (ch->scan_type.repeat > 1)
 544                         length = ch->scan_type.storagebits / 8 *
 545                                 ch->scan_type.repeat;
 546                 else
 547                         length = ch->scan_type.storagebits / 8;
 548                 bytes = ALIGN(bytes, length);
 549                 bytes += length;
 550         }
 551         if (timestamp) {
 552                 ch = iio_find_channel_from_si(indio_dev,
 553                                               indio_dev->scan_index_timestamp);
 554                 if (ch->scan_type.repeat > 1)
 555                         length = ch->scan_type.storagebits / 8 *
 556                                 ch->scan_type.repeat;
 557                 else
 558                         length = ch->scan_type.storagebits / 8;
 559                 bytes = ALIGN(bytes, length);
 560                 bytes += length;
 561         }
 562         return bytes;
 563 }
 564
 565 static void iio_buffer_activate(struct iio_dev *indio_dev,
 566         struct iio_buffer *buffer)
 567 {
 568         iio_buffer_get(buffer);
 569         list_add(&buffer->buffer_list, &indio_dev->buffer_list);
 570 }
 571
 572 static void iio_buffer_deactivate(struct iio_buffer *buffer)
 573 {
 574         list_del_init(&buffer->buffer_list);
 575         iio_buffer_put(buffer);
 576 }
 577
 578 void iio_disable_all_buffers(struct iio_dev *indio_dev)
 579 {
 580         struct iio_buffer *buffer, *_buffer;
 581
 582         if (list_empty(&indio_dev->buffer_list))
 583                 return;
 584
 585         if (indio_dev->setup_ops->predisable)
 586                 indio_dev->setup_ops->predisable(indio_dev);
 587
 588         list_for_each_entry_safe(buffer, _buffer,
 589                         &indio_dev->buffer_list, buffer_list)
 590                 iio_buffer_deactivate(buffer);
 591
 592         indio_dev->currentmode = INDIO_DIRECT_MODE;
 593         if (indio_dev->setup_ops->postdisable)
 594                 indio_dev->setup_ops->postdisable(indio_dev);
 595
 596         if (indio_dev->available_scan_masks == NULL)
 597                 kfree(indio_dev->active_scan_mask);
 598 }
 599
 600 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 601         struct iio_buffer *buffer)
 602 {
 603         unsigned int bytes;
 604
 605         if (!buffer->access->set_bytes_per_datum)
 606                 return;
 607
 608         bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
 609                 buffer->scan_timestamp);
 610
 611         buffer->access->set_bytes_per_datum(buffer, bytes);
 612 }
 613
 614 static int __iio_update_buffers(struct iio_dev *indio_dev,
 615                        struct iio_buffer *insert_buffer,
 616                        struct iio_buffer *remove_buffer)
 617 {
 618         int ret;
 619         int success = 0;
 620         struct iio_buffer *buffer;
 621         unsigned long *compound_mask;
 622         const unsigned long *old_mask;
 623
 624         /* Wind down existing buffers - iff there are any */
 625         if (!list_empty(&indio_dev->buffer_list)) {
 626                 if (indio_dev->setup_ops->predisable) {
 627                         ret = indio_dev->setup_ops->predisable(indio_dev);
 628                         if (ret)
 629                                 return ret;
 630                 }
 631                 indio_dev->currentmode = INDIO_DIRECT_MODE;
 632                 if (indio_dev->setup_ops->postdisable) {
 633                         ret = indio_dev->setup_ops->postdisable(indio_dev);
 634                         if (ret)
 635                                 return ret;
 636                 }
 637         }
 638         /* Keep a copy of current setup to allow roll back */
 639         old_mask = indio_dev->active_scan_mask;
 640         if (!indio_dev->available_scan_masks)
 641                 indio_dev->active_scan_mask = NULL;
 642
 643         if (remove_buffer)
 644                 iio_buffer_deactivate(remove_buffer);
 645         if (insert_buffer)
 646                 iio_buffer_activate(indio_dev, insert_buffer);
 647
 648         /* If no buffers in list, we are done */
 649         if (list_empty(&indio_dev->buffer_list)) {
 650                 indio_dev->currentmode = INDIO_DIRECT_MODE;
 651                 if (indio_dev->available_scan_masks == NULL)
 652                         kfree(old_mask);
 653                 return 0;
 654         }
 655
 656         /* What scan mask do we actually have? */
 657         compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
 658                                 sizeof(long), GFP_KERNEL);
 659         if (compound_mask == NULL) {
 660                 if (indio_dev->available_scan_masks == NULL)
 661                         kfree(old_mask);
 662                 return -ENOMEM;
 663         }
 664         indio_dev->scan_timestamp = 0;
 665
 666         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 667                 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 668                           indio_dev->masklength);
 669                 indio_dev->scan_timestamp |= buffer->scan_timestamp;
 670         }
 671         if (indio_dev->available_scan_masks) {
 672                 indio_dev->active_scan_mask =
 673                         iio_scan_mask_match(indio_dev->available_scan_masks,
 674                                             indio_dev->masklength,
 675                                             compound_mask);
 676                 if (indio_dev->active_scan_mask == NULL) {
 677                         /*
 678                          * Roll back.
 679                          * Note can only occur when adding a buffer.
 680                          */
 681                         iio_buffer_deactivate(insert_buffer);
 682                         if (old_mask) {
 683                                 indio_dev->active_scan_mask = old_mask;
 684                                 success = -EINVAL;
 685                         }
 686                         else {
 687                                 kfree(compound_mask);
 688                                 ret = -EINVAL;
 689                                 return ret;
 690                         }
 691                 }
 692         } else {
 693                 indio_dev->active_scan_mask = compound_mask;
 694         }
 695
 696         iio_update_demux(indio_dev);
 697
 698         /* Wind up again */
 699         if (indio_dev->setup_ops->preenable) {
 700                 ret = indio_dev->setup_ops->preenable(indio_dev);
 701                 if (ret) {
 702                         printk(KERN_ERR
 703                                "Buffer not started: buffer preenable failed (%d)\n", ret);
 704                         goto error_remove_inserted;
 705                 }
 706         }
 707         indio_dev->scan_bytes =
 708                 iio_compute_scan_bytes(indio_dev,
 709                                        indio_dev->active_scan_mask,
 710                                        indio_dev->scan_timestamp);
 711         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
 712                 iio_buffer_update_bytes_per_datum(indio_dev, buffer);
 713                 if (buffer->access->request_update) {
 714                         ret = buffer->access->request_update(buffer);
 715                         if (ret) {
 716                                 printk(KERN_INFO
 717                                        "Buffer not started: buffer parameter update failed (%d)\n", ret);
 718                                 goto error_run_postdisable;
 719                         }
 720                 }
 721         }
 722         if (indio_dev->info->update_scan_mode) {
 723                 ret = indio_dev->info
 724                         ->update_scan_mode(indio_dev,
 725                                            indio_dev->active_scan_mask);
 726                 if (ret < 0) {
 727                         printk(KERN_INFO "Buffer not started: update scan mode failed (%d)\n", ret);
 728                         goto error_run_postdisable;
 729                 }
 730         }
 731         /* Definitely possible for devices to support both of these. */
 732         if (indio_dev->modes & INDIO_BUFFER_TRIGGERED) {
 733                 if (!indio_dev->trig) {
 734                         printk(KERN_INFO "Buffer not started: no trigger\n");
 735                         ret = -EINVAL;
 736                         /* Can only occur on first buffer */
 737                         goto error_run_postdisable;
 738                 }
 739                 indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
 740         } else if (indio_dev->modes & INDIO_BUFFER_HARDWARE) {
 741                 indio_dev->currentmode = INDIO_BUFFER_HARDWARE;
 742         } else { /* Should never be reached */
 743                 ret = -EINVAL;
 744                 goto error_run_postdisable;
 745         }
 746
 747         if (indio_dev->setup_ops->postenable) {
 748                 ret = indio_dev->setup_ops->postenable(indio_dev);
 749                 if (ret) {
 750                         printk(KERN_INFO
 751                                "Buffer not started: postenable failed (%d)\n", ret);
 752                         indio_dev->currentmode = INDIO_DIRECT_MODE;
 753                         if (indio_dev->setup_ops->postdisable)
 754                                 indio_dev->setup_ops->postdisable(indio_dev);
 755                         goto error_disable_all_buffers;
 756                 }
 757         }
 758
 759         if (indio_dev->available_scan_masks)
 760                 kfree(compound_mask);
 761         else
 762                 kfree(old_mask);
 763
 764         return success;
 765
 766 error_disable_all_buffers:
 767         indio_dev->currentmode = INDIO_DIRECT_MODE;
 768 error_run_postdisable:
 769         if (indio_dev->setup_ops->postdisable)
 770                 indio_dev->setup_ops->postdisable(indio_dev);
 771 error_remove_inserted:
 772         if (insert_buffer)
 773                 iio_buffer_deactivate(insert_buffer);
 774         indio_dev->active_scan_mask = old_mask;
 775         kfree(compound_mask);
 776         return ret;
 777 }
 778
 779 int iio_update_buffers(struct iio_dev *indio_dev,
 780                        struct iio_buffer *insert_buffer,
 781                        struct iio_buffer *remove_buffer)
 782 {
 783         int ret;
 784
 785         if (insert_buffer == remove_buffer)
 786                 return 0;
 787
 788         mutex_lock(&indio_dev->info_exist_lock);
 789         mutex_lock(&indio_dev->mlock);
 790
 791         if (insert_buffer && iio_buffer_is_active(insert_buffer))
 792                 insert_buffer = NULL;
 793
 794         if (remove_buffer && !iio_buffer_is_active(remove_buffer))
 795                 remove_buffer = NULL;
 796
 797         if (!insert_buffer && !remove_buffer) {
 798                 ret = 0;
 799                 goto out_unlock;
 800         }
 801
 802         if (indio_dev->info == NULL) {
 803                 ret = -ENODEV;
 804                 goto out_unlock;
 805         }
 806
 807         ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 808
 809 out_unlock:
 810         mutex_unlock(&indio_dev->mlock);
 811         mutex_unlock(&indio_dev->info_exist_lock);
 812
 813         return ret;
 814 }
 815 EXPORT_SYMBOL_GPL(iio_update_buffers);
 816
 817 ssize_t iio_buffer_store_enable(struct device *dev,
 818                                 struct device_attribute *attr,
 819                                 const char *buf,
 820                                 size_t len)
 821 {
 822         int ret;
 823         bool requested_state;
 824         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 825         bool inlist;
 826
 827         ret = strtobool(buf, &requested_state);
 828         if (ret < 0)
 829                 return ret;
 830
 831         mutex_lock(&indio_dev->mlock);
 832
 833         /* Find out if it is in the list */
 834         inlist = iio_buffer_is_active(indio_dev->buffer);
 835         /* Already in desired state */
 836         if (inlist == requested_state)
 837                 goto done;
 838
 839         if (requested_state)
 840                 ret = __iio_update_buffers(indio_dev,
 841                                          indio_dev->buffer, NULL);
 842         else
 843                 ret = __iio_update_buffers(indio_dev,
 844                                          NULL, indio_dev->buffer);
 845
 846         if (ret < 0)
 847                 goto done;
 848 done:
 849         mutex_unlock(&indio_dev->mlock);
 850         return (ret < 0) ? ret : len;
 851 }
 852 EXPORT_SYMBOL(iio_buffer_store_enable);
 853
 854 /**
 855  * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
 856  * @indio_dev: the iio device
 857  * @mask: scan mask to be checked
 858  *
 859  * Return true if exactly one bit is set in the scan mask, false otherwise. It
 860  * can be used for devices where only one channel can be active for sampling at
 861  * a time.
 862  */
 863 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
 864         const unsigned long *mask)
 865 {
 866         return bitmap_weight(mask, indio_dev->masklength) == 1;
 867 }
 868 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
 869
 870 int iio_scan_mask_query(struct iio_dev *indio_dev,
 871                         struct iio_buffer *buffer, int bit)
 872 {
 873         if (bit > indio_dev->masklength)
 874                 return -EINVAL;
 875
 876         if (!buffer->scan_mask)
 877                 return 0;
 878
 879         /* Ensure return value is 0 or 1. */
 880         return !!test_bit(bit, buffer->scan_mask);
 881 };
 882 EXPORT_SYMBOL_GPL(iio_scan_mask_query);
 883
 884 /**
 885  * struct iio_demux_table() - table describing demux memcpy ops
 886  * @from:       index to copy from
 887  * @to:         index to copy to
 888  * @length:     how many bytes to copy
 889  * @l:          list head used for management
 890  */
 891 struct iio_demux_table {
 892         unsigned from;
 893         unsigned to;
 894         unsigned length;
 895         struct list_head l;
 896 };
 897
 898 static const void *iio_demux(struct iio_buffer *buffer,
 899                                  const void *datain)
 900 {
 901         struct iio_demux_table *t;
 902
 903         if (list_empty(&buffer->demux_list))
 904                 return datain;
 905         list_for_each_entry(t, &buffer->demux_list, l)
 906                 memcpy(buffer->demux_bounce + t->to,
 907                        datain + t->from, t->length);
 908
 909         return buffer->demux_bounce;
 910 }
 911
 912 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
 913 {
 914         const void *dataout = iio_demux(buffer, data);
 915
 916         return buffer->access->store_to(buffer, dataout);
 917 }
 918
 919 static void iio_buffer_demux_free(struct iio_buffer *buffer)
 920 {
 921         struct iio_demux_table *p, *q;
 922         list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
 923                 list_del(&p->l);
 924                 kfree(p);
 925         }
 926 }
 927
 928
 929 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
 930 {
 931         int ret;
 932         struct iio_buffer *buf;
 933
 934         list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
 935                 ret = iio_push_to_buffer(buf, data);
 936                 if (ret < 0)
 937                         return ret;
 938         }
 939
 940         return 0;
 941 }
 942 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
 943
 944 static int iio_buffer_add_demux(struct iio_buffer *buffer,
 945         struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
 946         unsigned int length)
 947 {
 948
 949         if (*p && (*p)->from + (*p)->length == in_loc &&
 950                 (*p)->to + (*p)->length == out_loc) {
 951                 (*p)->length += length;
 952         } else {
 953                 *p = kmalloc(sizeof(**p), GFP_KERNEL);
 954                 if (*p == NULL)
 955                         return -ENOMEM;
 956                 (*p)->from = in_loc;
 957                 (*p)->to = out_loc;
 958                 (*p)->length = length;
 959                 list_add_tail(&(*p)->l, &buffer->demux_list);
 960         }
 961
 962         return 0;
 963 }
 964
 965 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
 966                                    struct iio_buffer *buffer)
 967 {
 968         const struct iio_chan_spec *ch;
 969         int ret, in_ind = -1, out_ind, length;
 970         unsigned in_loc = 0, out_loc = 0;
 971         struct iio_demux_table *p = NULL;
 972
 973         /* Clear out any old demux */
 974         iio_buffer_demux_free(buffer);
 975         kfree(buffer->demux_bounce);
 976         buffer->demux_bounce = NULL;
 977
 978         /* First work out which scan mode we will actually have */
 979         if (bitmap_equal(indio_dev->active_scan_mask,
 980                          buffer->scan_mask,
 981                          indio_dev->masklength))
 982                 return 0;
 983
 984         /* Now we have the two masks, work from least sig and build up sizes */
 985         for_each_set_bit(out_ind,
 986                          buffer->scan_mask,
 987                          indio_dev->masklength) {
 988                 in_ind = find_next_bit(indio_dev->active_scan_mask,
 989                                        indio_dev->masklength,
 990                                        in_ind + 1);
 991                 while (in_ind != out_ind) {
 992                         in_ind = find_next_bit(indio_dev->active_scan_mask,
 993                                                indio_dev->masklength,
 994                                                in_ind + 1);
 995                         ch = iio_find_channel_from_si(indio_dev, in_ind);
 996                         if (ch->scan_type.repeat > 1)
 997                                 length = ch->scan_type.storagebits / 8 *
 998                                         ch->scan_type.repeat;
 999                         else
1000                                 length = ch->scan_type.storagebits / 8;
1001                         /* Make sure we are aligned */
1002                         in_loc = roundup(in_loc, length) + length;
1003                 }
1004                 ch = iio_find_channel_from_si(indio_dev, in_ind);
1005                 if (ch->scan_type.repeat > 1)
1006                         length = ch->scan_type.storagebits / 8 *
1007                                 ch->scan_type.repeat;
1008                 else
1009                         length = ch->scan_type.storagebits / 8;
1010                 out_loc = roundup(out_loc, length);
1011                 in_loc = roundup(in_loc, length);
1012                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
1013                 if (ret)
1014                         goto error_clear_mux_table;
1015                 out_loc += length;
1016                 in_loc += length;
1017         }
1018         /* Relies on scan_timestamp being last */
1019         if (buffer->scan_timestamp) {
1020                 ch = iio_find_channel_from_si(indio_dev,
1021                         indio_dev->scan_index_timestamp);
1022                 if (ch->scan_type.repeat > 1)
1023                         length = ch->scan_type.storagebits / 8 *
1024                                 ch->scan_type.repeat;
1025                 else
1026                         length = ch->scan_type.storagebits / 8;
1027                 out_loc = roundup(out_loc, length);
1028                 in_loc = roundup(in_loc, length);
1029                 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
1030                 if (ret)
1031                         goto error_clear_mux_table;
1032                 out_loc += length;
1033                 in_loc += length;
1034         }
1035         buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
1036         if (buffer->demux_bounce == NULL) {
1037                 ret = -ENOMEM;
1038                 goto error_clear_mux_table;
1039         }
1040         return 0;
1041
1042 error_clear_mux_table:
1043         iio_buffer_demux_free(buffer);
1044
1045         return ret;
1046 }
1047
1048 int iio_update_demux(struct iio_dev *indio_dev)
1049 {
1050         struct iio_buffer *buffer;
1051         int ret;
1052
1053         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1054                 ret = iio_buffer_update_demux(indio_dev, buffer);
1055                 if (ret < 0)
1056                         goto error_clear_mux_table;
1057         }
1058         return 0;
1059
1060 error_clear_mux_table:
1061         list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
1062                 iio_buffer_demux_free(buffer);
1063
1064         return ret;
1065 }
1066 EXPORT_SYMBOL_GPL(iio_update_demux);
1067
1068 /**
1069  * iio_buffer_release() - Free a buffer's resources
1070  * @ref: Pointer to the kref embedded in the iio_buffer struct
1071  *
1072  * This function is called when the last reference to the buffer has been
1073  * dropped. It will typically free all resources allocated by the buffer. Do not
1074  * call this function manually, always use iio_buffer_put() when done using a
1075  * buffer.
1076  */
1077 static void iio_buffer_release(struct kref *ref)
1078 {
1079         struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1080
1081         buffer->access->release(buffer);
1082 }
1083
1084 /**
1085  * iio_buffer_get() - Grab a reference to the buffer
1086  * @buffer: The buffer to grab a reference for, may be NULL
1087  *
1088  * Returns the pointer to the buffer that was passed into the function.
1089  */
1090 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1091 {
1092         if (buffer)
1093                 kref_get(&buffer->ref);
1094
1095         return buffer;
1096 }
1097 EXPORT_SYMBOL_GPL(iio_buffer_get);
1098
1099 /**
1100  * iio_buffer_put() - Release the reference to the buffer
1101  * @buffer: The buffer to release the reference for, may be NULL
1102  */
1103 void iio_buffer_put(struct iio_buffer *buffer)
1104 {
1105         if (buffer)
1106                 kref_put(&buffer->ref, iio_buffer_release);
1107 }
1108 EXPORT_SYMBOL_GPL(iio_buffer_put);