1/* The industrial I/O core
2 *
3 * Copyright (c) 2008 Jonathan Cameron
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
8 *
9 * Handling of buffer allocation / resizing.
10 *
11 *
12 * Things to look at here.
13 * - Better memory allocation techniques?
14 * - Alternative access techniques?
15 */
16#include <linux/kernel.h>
17#include <linux/export.h>
18#include <linux/device.h>
19#include <linux/fs.h>
20#include <linux/cdev.h>
21#include <linux/slab.h>
22#include <linux/poll.h>
23#include <linux/sched/signal.h>
24
25#include <linux/iio/iio.h>
26#include "iio_core.h"
27#include <linux/iio/sysfs.h>
28#include <linux/iio/buffer.h>
29#include <linux/iio/buffer_impl.h>
30
31static const char * const iio_endian_prefix[] = {
32 [IIO_BE] = "be",
33 [IIO_LE] = "le",
34};
35
36static bool iio_buffer_is_active(struct iio_buffer *buf)
37{
38 return !list_empty(&buf->buffer_list);
39}
40
41static size_t iio_buffer_data_available(struct iio_buffer *buf)
42{
43 return buf->access->data_available(buf);
44}
45
46static int iio_buffer_flush_hwfifo(struct iio_dev *indio_dev,
47 struct iio_buffer *buf, size_t required)
48{
49 if (!indio_dev->info->hwfifo_flush_to_buffer)
50 return -ENODEV;
51
52 return indio_dev->info->hwfifo_flush_to_buffer(indio_dev, required);
53}
54
55static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
56 size_t to_wait, int to_flush)
57{
58 size_t avail;
59 int flushed = 0;
60
61 /* wakeup if the device was unregistered */
62 if (!indio_dev->info)
63 return true;
64
65 /* drain the buffer if it was disabled */
66 if (!iio_buffer_is_active(buf)) {
67 to_wait = min_t(size_t, to_wait, 1);
68 to_flush = 0;
69 }
70
71 avail = iio_buffer_data_available(buf);
72
73 if (avail >= to_wait) {
74 /* force a flush for non-blocking reads */
75 if (!to_wait && avail < to_flush)
76 iio_buffer_flush_hwfifo(indio_dev, buf,
77 to_flush - avail);
78 return true;
79 }
80
81 if (to_flush)
82 flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
83 to_wait - avail);
84 if (flushed <= 0)
85 return false;
86
87 if (avail + flushed >= to_wait)
88 return true;
89
90 return false;
91}
92
93/**
94 * iio_buffer_read_first_n_outer() - chrdev read for buffer access
95 * @filp: File structure pointer for the char device
96 * @buf: Destination buffer for iio buffer read
97 * @n: First n bytes to read
98 * @f_ps: Long offset provided by the user as a seek position
99 *
100 * This function relies on all buffer implementations having an
101 * iio_buffer as their first element.
102 *
103 * Return: negative values corresponding to error codes or ret != 0
104 * for ending the reading activity
105 **/
106ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
107 size_t n, loff_t *f_ps)
108{
109 struct iio_dev *indio_dev = filp->private_data;
110 struct iio_buffer *rb = indio_dev->buffer;
111 DEFINE_WAIT_FUNC(wait, woken_wake_function);
112 size_t datum_size;
113 size_t to_wait;
114 int ret = 0;
115
116 if (!indio_dev->info)
117 return -ENODEV;
118
119 if (!rb || !rb->access->read_first_n)
120 return -EINVAL;
121
122 datum_size = rb->bytes_per_datum;
123
124 /*
125 * If datum_size is 0 there will never be anything to read from the
126 * buffer, so signal end of file now.
127 */
128 if (!datum_size)
129 return 0;
130
131 if (filp->f_flags & O_NONBLOCK)
132 to_wait = 0;
133 else
134 to_wait = min_t(size_t, n / datum_size, rb->watermark);
135
136 add_wait_queue(&rb->pollq, &wait);
137 do {
138 if (!indio_dev->info) {
139 ret = -ENODEV;
140 break;
141 }
142
143 if (!iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size)) {
144 if (signal_pending(current)) {
145 ret = -ERESTARTSYS;
146 break;
147 }
148
149 wait_woken(&wait, TASK_INTERRUPTIBLE,
150 MAX_SCHEDULE_TIMEOUT);
151 continue;
152 }
153
154 ret = rb->access->read_first_n(rb, n, buf);
155 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
156 ret = -EAGAIN;
157 } while (ret == 0);
158 remove_wait_queue(&rb->pollq, &wait);
159
160 return ret;
161}
162
163/**
164 * iio_buffer_poll() - poll the buffer to find out if it has data
165 * @filp: File structure pointer for device access
166 * @wait: Poll table structure pointer for which the driver adds
167 * a wait queue
168 *
169 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
170 * or 0 for other cases
171 */
172__poll_t iio_buffer_poll(struct file *filp,
173 struct poll_table_struct *wait)
174{
175 struct iio_dev *indio_dev = filp->private_data;
176 struct iio_buffer *rb = indio_dev->buffer;
177
178 if (!indio_dev->info || rb == NULL)
179 return 0;
180
181 poll_wait(filp, &rb->pollq, wait);
182 if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0))
183 return EPOLLIN | EPOLLRDNORM;
184 return 0;
185}
186
187/**
188 * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
189 * @indio_dev: The IIO device
190 *
191 * Wakes up the event waitqueue used for poll(). Should usually
192 * be called when the device is unregistered.
193 */
194void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
195{
196 if (!indio_dev->buffer)
197 return;
198
199 wake_up(&indio_dev->buffer->pollq);
200}
201
202void iio_buffer_init(struct iio_buffer *buffer)
203{
204 INIT_LIST_HEAD(&buffer->demux_list);
205 INIT_LIST_HEAD(&buffer->buffer_list);
206 init_waitqueue_head(&buffer->pollq);
207 kref_init(&buffer->ref);
208 if (!buffer->watermark)
209 buffer->watermark = 1;
210}
211EXPORT_SYMBOL(iio_buffer_init);
212
213/**
214 * iio_buffer_set_attrs - Set buffer specific attributes
215 * @buffer: The buffer for which we are setting attributes
216 * @attrs: Pointer to a null terminated list of pointers to attributes
217 */
218void iio_buffer_set_attrs(struct iio_buffer *buffer,
219 const struct attribute **attrs)
220{
221 buffer->attrs = attrs;
222}
223EXPORT_SYMBOL_GPL(iio_buffer_set_attrs);
224
225static ssize_t iio_show_scan_index(struct device *dev,
226 struct device_attribute *attr,
227 char *buf)
228{
229 return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
230}
231
232static ssize_t iio_show_fixed_type(struct device *dev,
233 struct device_attribute *attr,
234 char *buf)
235{
236 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
237 u8 type = this_attr->c->scan_type.endianness;
238
239 if (type == IIO_CPU) {
240#ifdef __LITTLE_ENDIAN
241 type = IIO_LE;
242#else
243 type = IIO_BE;
244#endif
245 }
246 if (this_attr->c->scan_type.repeat > 1)
247 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
248 iio_endian_prefix[type],
249 this_attr->c->scan_type.sign,
250 this_attr->c->scan_type.realbits,
251 this_attr->c->scan_type.storagebits,
252 this_attr->c->scan_type.repeat,
253 this_attr->c->scan_type.shift);
254 else
255 return sprintf(buf, "%s:%c%d/%d>>%u\n",
256 iio_endian_prefix[type],
257 this_attr->c->scan_type.sign,
258 this_attr->c->scan_type.realbits,
259 this_attr->c->scan_type.storagebits,
260 this_attr->c->scan_type.shift);
261}
262
263static ssize_t iio_scan_el_show(struct device *dev,
264 struct device_attribute *attr,
265 char *buf)
266{
267 int ret;
268 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
269
270 /* Ensure ret is 0 or 1. */
271 ret = !!test_bit(to_iio_dev_attr(attr)->address,
272 indio_dev->buffer->scan_mask);
273
274 return sprintf(buf, "%d\n", ret);
275}
276
277/* Note NULL used as error indicator as it doesn't make sense. */
278static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
279 unsigned int masklength,
280 const unsigned long *mask,
281 bool strict)
282{
283 if (bitmap_empty(mask, masklength))
284 return NULL;
285 while (*av_masks) {
286 if (strict) {
287 if (bitmap_equal(mask, av_masks, masklength))
288 return av_masks;
289 } else {
290 if (bitmap_subset(mask, av_masks, masklength))
291 return av_masks;
292 }
293 av_masks += BITS_TO_LONGS(masklength);
294 }
295 return NULL;
296}
297
298static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
299 const unsigned long *mask)
300{
301 if (!indio_dev->setup_ops->validate_scan_mask)
302 return true;
303
304 return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
305}
306
307/**
308 * iio_scan_mask_set() - set particular bit in the scan mask
309 * @indio_dev: the iio device
310 * @buffer: the buffer whose scan mask we are interested in
311 * @bit: the bit to be set.
312 *
313 * Note that at this point we have no way of knowing what other
314 * buffers might request, hence this code only verifies that the
315 * individual buffers request is plausible.
316 */
317static int iio_scan_mask_set(struct iio_dev *indio_dev,
318 struct iio_buffer *buffer, int bit)
319{
320 const unsigned long *mask;
321 unsigned long *trialmask;
322
323 trialmask = kmalloc_array(BITS_TO_LONGS(indio_dev->masklength),
324 sizeof(*trialmask),
325 GFP_KERNEL);
326 if (trialmask == NULL)
327 return -ENOMEM;
328 if (!indio_dev->masklength) {
329 WARN(1, "Trying to set scanmask prior to registering buffer\n");
330 goto err_invalid_mask;
331 }
332 bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
333 set_bit(bit, trialmask);
334
335 if (!iio_validate_scan_mask(indio_dev, trialmask))
336 goto err_invalid_mask;
337
338 if (indio_dev->available_scan_masks) {
339 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
340 indio_dev->masklength,
341 trialmask, false);
342 if (!mask)
343 goto err_invalid_mask;
344 }
345 bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
346
347 kfree(trialmask);
348
349 return 0;
350
351err_invalid_mask:
352 kfree(trialmask);
353 return -EINVAL;
354}
355
356static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
357{
358 clear_bit(bit, buffer->scan_mask);
359 return 0;
360}
361
362static int iio_scan_mask_query(struct iio_dev *indio_dev,
363 struct iio_buffer *buffer, int bit)
364{
365 if (bit > indio_dev->masklength)
366 return -EINVAL;
367
368 if (!buffer->scan_mask)
369 return 0;
370
371 /* Ensure return value is 0 or 1. */
372 return !!test_bit(bit, buffer->scan_mask);
373};
374
375static ssize_t iio_scan_el_store(struct device *dev,
376 struct device_attribute *attr,
377 const char *buf,
378 size_t len)
379{
380 int ret;
381 bool state;
382 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
383 struct iio_buffer *buffer = indio_dev->buffer;
384 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
385
386 ret = strtobool(buf, &state);
387 if (ret < 0)
388 return ret;
389 mutex_lock(&indio_dev->mlock);
390 if (iio_buffer_is_active(indio_dev->buffer)) {
391 ret = -EBUSY;
392 goto error_ret;
393 }
394 ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
395 if (ret < 0)
396 goto error_ret;
397 if (!state && ret) {
398 ret = iio_scan_mask_clear(buffer, this_attr->address);
399 if (ret)
400 goto error_ret;
401 } else if (state && !ret) {
402 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
403 if (ret)
404 goto error_ret;
405 }
406
407error_ret:
408 mutex_unlock(&indio_dev->mlock);
409
410 return ret < 0 ? ret : len;
411
412}
413
414static ssize_t iio_scan_el_ts_show(struct device *dev,
415 struct device_attribute *attr,
416 char *buf)
417{
418 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
419 return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
420}
421
422static ssize_t iio_scan_el_ts_store(struct device *dev,
423 struct device_attribute *attr,
424 const char *buf,
425 size_t len)
426{
427 int ret;
428 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
429 bool state;
430
431 ret = strtobool(buf, &state);
432 if (ret < 0)
433 return ret;
434
435 mutex_lock(&indio_dev->mlock);
436 if (iio_buffer_is_active(indio_dev->buffer)) {
437 ret = -EBUSY;
438 goto error_ret;
439 }
440 indio_dev->buffer->scan_timestamp = state;
441error_ret:
442 mutex_unlock(&indio_dev->mlock);
443
444 return ret ? ret : len;
445}
446
447static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
448 const struct iio_chan_spec *chan)
449{
450 int ret, attrcount = 0;
451 struct iio_buffer *buffer = indio_dev->buffer;
452
453 ret = __iio_add_chan_devattr("index",
454 chan,
455 &iio_show_scan_index,
456 NULL,
457 0,
458 IIO_SEPARATE,
459 &indio_dev->dev,
460 &buffer->scan_el_dev_attr_list);
461 if (ret)
462 return ret;
463 attrcount++;
464 ret = __iio_add_chan_devattr("type",
465 chan,
466 &iio_show_fixed_type,
467 NULL,
468 0,
469 0,
470 &indio_dev->dev,
471 &buffer->scan_el_dev_attr_list);
472 if (ret)
473 return ret;
474 attrcount++;
475 if (chan->type != IIO_TIMESTAMP)
476 ret = __iio_add_chan_devattr("en",
477 chan,
478 &iio_scan_el_show,
479 &iio_scan_el_store,
480 chan->scan_index,
481 0,
482 &indio_dev->dev,
483 &buffer->scan_el_dev_attr_list);
484 else
485 ret = __iio_add_chan_devattr("en",
486 chan,
487 &iio_scan_el_ts_show,
488 &iio_scan_el_ts_store,
489 chan->scan_index,
490 0,
491 &indio_dev->dev,
492 &buffer->scan_el_dev_attr_list);
493 if (ret)
494 return ret;
495 attrcount++;
496 ret = attrcount;
497 return ret;
498}
499
500static ssize_t iio_buffer_read_length(struct device *dev,
501 struct device_attribute *attr,
502 char *buf)
503{
504 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
505 struct iio_buffer *buffer = indio_dev->buffer;
506
507 return sprintf(buf, "%d\n", buffer->length);
508}
509
510static ssize_t iio_buffer_write_length(struct device *dev,
511 struct device_attribute *attr,
512 const char *buf, size_t len)
513{
514 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
515 struct iio_buffer *buffer = indio_dev->buffer;
516 unsigned int val;
517 int ret;
518
519 ret = kstrtouint(buf, 10, &val);
520 if (ret)
521 return ret;
522
523 if (val == buffer->length)
524 return len;
525
526 mutex_lock(&indio_dev->mlock);
527 if (iio_buffer_is_active(indio_dev->buffer)) {
528 ret = -EBUSY;
529 } else {
530 buffer->access->set_length(buffer, val);
531 ret = 0;
532 }
533 if (ret)
534 goto out;
535 if (buffer->length && buffer->length < buffer->watermark)
536 buffer->watermark = buffer->length;
537out:
538 mutex_unlock(&indio_dev->mlock);
539
540 return ret ? ret : len;
541}
542
543static ssize_t iio_buffer_show_enable(struct device *dev,
544 struct device_attribute *attr,
545 char *buf)
546{
547 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
548 return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
549}
550
551static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
552 unsigned int scan_index)
553{
554 const struct iio_chan_spec *ch;
555 unsigned int bytes;
556
557 ch = iio_find_channel_from_si(indio_dev, scan_index);
558 bytes = ch->scan_type.storagebits / 8;
559 if (ch->scan_type.repeat > 1)
560 bytes *= ch->scan_type.repeat;
561 return bytes;
562}
563
564static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
565{
566 return iio_storage_bytes_for_si(indio_dev,
567 indio_dev->scan_index_timestamp);
568}
569
570static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
571 const unsigned long *mask, bool timestamp)
572{
573 unsigned bytes = 0;
574 int length, i;
575
576 /* How much space will the demuxed element take? */
577 for_each_set_bit(i, mask,
578 indio_dev->masklength) {
579 length = iio_storage_bytes_for_si(indio_dev, i);
580 bytes = ALIGN(bytes, length);
581 bytes += length;
582 }
583
584 if (timestamp) {
585 length = iio_storage_bytes_for_timestamp(indio_dev);
586 bytes = ALIGN(bytes, length);
587 bytes += length;
588 }
589 return bytes;
590}
591
592static void iio_buffer_activate(struct iio_dev *indio_dev,
593 struct iio_buffer *buffer)
594{
595 iio_buffer_get(buffer);
596 list_add(&buffer->buffer_list, &indio_dev->buffer_list);
597}
598
599static void iio_buffer_deactivate(struct iio_buffer *buffer)
600{
601 list_del_init(&buffer->buffer_list);
602 wake_up_interruptible(&buffer->pollq);
603 iio_buffer_put(buffer);
604}
605
606static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
607{
608 struct iio_buffer *buffer, *_buffer;
609
610 list_for_each_entry_safe(buffer, _buffer,
611 &indio_dev->buffer_list, buffer_list)
612 iio_buffer_deactivate(buffer);
613}
614
615static int iio_buffer_enable(struct iio_buffer *buffer,
616 struct iio_dev *indio_dev)
617{
618 if (!buffer->access->enable)
619 return 0;
620 return buffer->access->enable(buffer, indio_dev);
621}
622
623static int iio_buffer_disable(struct iio_buffer *buffer,
624 struct iio_dev *indio_dev)
625{
626 if (!buffer->access->disable)
627 return 0;
628 return buffer->access->disable(buffer, indio_dev);
629}
630
631static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
632 struct iio_buffer *buffer)
633{
634 unsigned int bytes;
635
636 if (!buffer->access->set_bytes_per_datum)
637 return;
638
639 bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
640 buffer->scan_timestamp);
641
642 buffer->access->set_bytes_per_datum(buffer, bytes);
643}
644
645static int iio_buffer_request_update(struct iio_dev *indio_dev,
646 struct iio_buffer *buffer)
647{
648 int ret;
649
650 iio_buffer_update_bytes_per_datum(indio_dev, buffer);
651 if (buffer->access->request_update) {
652 ret = buffer->access->request_update(buffer);
653 if (ret) {
654 dev_dbg(&indio_dev->dev,
655 "Buffer not started: buffer parameter update failed (%d)\n",
656 ret);
657 return ret;
658 }
659 }
660
661 return 0;
662}
663
664static void iio_free_scan_mask(struct iio_dev *indio_dev,
665 const unsigned long *mask)
666{
667 /* If the mask is dynamically allocated free it, otherwise do nothing */
668 if (!indio_dev->available_scan_masks)
669 kfree(mask);
670}
671
672struct iio_device_config {
673 unsigned int mode;
674 unsigned int watermark;
675 const unsigned long *scan_mask;
676 unsigned int scan_bytes;
677 bool scan_timestamp;
678};
679
680static int iio_verify_update(struct iio_dev *indio_dev,
681 struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
682 struct iio_device_config *config)
683{
684 unsigned long *compound_mask;
685 const unsigned long *scan_mask;
686 bool strict_scanmask = false;
687 struct iio_buffer *buffer;
688 bool scan_timestamp;
689 unsigned int modes;
690
691 memset(config, 0, sizeof(*config));
692 config->watermark = ~0;
693
694 /*
695 * If there is just one buffer and we are removing it there is nothing
696 * to verify.
697 */
698 if (remove_buffer && !insert_buffer &&
699 list_is_singular(&indio_dev->buffer_list))
700 return 0;
701
702 modes = indio_dev->modes;
703
704 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
705 if (buffer == remove_buffer)
706 continue;
707 modes &= buffer->access->modes;
708 config->watermark = min(config->watermark, buffer->watermark);
709 }
710
711 if (insert_buffer) {
712 modes &= insert_buffer->access->modes;
713 config->watermark = min(config->watermark,
714 insert_buffer->watermark);
715 }
716
717 /* Definitely possible for devices to support both of these. */
718 if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
719 config->mode = INDIO_BUFFER_TRIGGERED;
720 } else if (modes & INDIO_BUFFER_HARDWARE) {
721 /*
722 * Keep things simple for now and only allow a single buffer to
723 * be connected in hardware mode.
724 */
725 if (insert_buffer && !list_empty(&indio_dev->buffer_list))
726 return -EINVAL;
727 config->mode = INDIO_BUFFER_HARDWARE;
728 strict_scanmask = true;
729 } else if (modes & INDIO_BUFFER_SOFTWARE) {
730 config->mode = INDIO_BUFFER_SOFTWARE;
731 } else {
732 /* Can only occur on first buffer */
733 if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
734 dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
735 return -EINVAL;
736 }
737
738 /* What scan mask do we actually have? */
739 compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
740 sizeof(long), GFP_KERNEL);
741 if (compound_mask == NULL)
742 return -ENOMEM;
743
744 scan_timestamp = false;
745
746 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
747 if (buffer == remove_buffer)
748 continue;
749 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
750 indio_dev->masklength);
751 scan_timestamp |= buffer->scan_timestamp;
752 }
753
754 if (insert_buffer) {
755 bitmap_or(compound_mask, compound_mask,
756 insert_buffer->scan_mask, indio_dev->masklength);
757 scan_timestamp |= insert_buffer->scan_timestamp;
758 }
759
760 if (indio_dev->available_scan_masks) {
761 scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
762 indio_dev->masklength,
763 compound_mask,
764 strict_scanmask);
765 kfree(compound_mask);
766 if (scan_mask == NULL)
767 return -EINVAL;
768 } else {
769 scan_mask = compound_mask;
770 }
771
772 config->scan_bytes = iio_compute_scan_bytes(indio_dev,
773 scan_mask, scan_timestamp);
774 config->scan_mask = scan_mask;
775 config->scan_timestamp = scan_timestamp;
776
777 return 0;
778}
779
780/**
781 * struct iio_demux_table - table describing demux memcpy ops
782 * @from: index to copy from
783 * @to: index to copy to
784 * @length: how many bytes to copy
785 * @l: list head used for management
786 */
787struct iio_demux_table {
788 unsigned from;
789 unsigned to;
790 unsigned length;
791 struct list_head l;
792};
793
794static void iio_buffer_demux_free(struct iio_buffer *buffer)
795{
796 struct iio_demux_table *p, *q;
797 list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
798 list_del(&p->l);
799 kfree(p);
800 }
801}
802
803static int iio_buffer_add_demux(struct iio_buffer *buffer,
804 struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
805 unsigned int length)
806{
807
808 if (*p && (*p)->from + (*p)->length == in_loc &&
809 (*p)->to + (*p)->length == out_loc) {
810 (*p)->length += length;
811 } else {
812 *p = kmalloc(sizeof(**p), GFP_KERNEL);
813 if (*p == NULL)
814 return -ENOMEM;
815 (*p)->from = in_loc;
816 (*p)->to = out_loc;
817 (*p)->length = length;
818 list_add_tail(&(*p)->l, &buffer->demux_list);
819 }
820
821 return 0;
822}
823
824static int iio_buffer_update_demux(struct iio_dev *indio_dev,
825 struct iio_buffer *buffer)
826{
827 int ret, in_ind = -1, out_ind, length;
828 unsigned in_loc = 0, out_loc = 0;
829 struct iio_demux_table *p = NULL;
830
831 /* Clear out any old demux */
832 iio_buffer_demux_free(buffer);
833 kfree(buffer->demux_bounce);
834 buffer->demux_bounce = NULL;
835
836 /* First work out which scan mode we will actually have */
837 if (bitmap_equal(indio_dev->active_scan_mask,
838 buffer->scan_mask,
839 indio_dev->masklength))
840 return 0;
841
842 /* Now we have the two masks, work from least sig and build up sizes */
843 for_each_set_bit(out_ind,
844 buffer->scan_mask,
845 indio_dev->masklength) {
846 in_ind = find_next_bit(indio_dev->active_scan_mask,
847 indio_dev->masklength,
848 in_ind + 1);
849 while (in_ind != out_ind) {
850 in_ind = find_next_bit(indio_dev->active_scan_mask,
851 indio_dev->masklength,
852 in_ind + 1);
853 length = iio_storage_bytes_for_si(indio_dev, in_ind);
854 /* Make sure we are aligned */
855 in_loc = roundup(in_loc, length) + length;
856 }
857 length = iio_storage_bytes_for_si(indio_dev, in_ind);
858 out_loc = roundup(out_loc, length);
859 in_loc = roundup(in_loc, length);
860 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
861 if (ret)
862 goto error_clear_mux_table;
863 out_loc += length;
864 in_loc += length;
865 }
866 /* Relies on scan_timestamp being last */
867 if (buffer->scan_timestamp) {
868 length = iio_storage_bytes_for_timestamp(indio_dev);
869 out_loc = roundup(out_loc, length);
870 in_loc = roundup(in_loc, length);
871 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
872 if (ret)
873 goto error_clear_mux_table;
874 out_loc += length;
875 in_loc += length;
876 }
877 buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
878 if (buffer->demux_bounce == NULL) {
879 ret = -ENOMEM;
880 goto error_clear_mux_table;
881 }
882 return 0;
883
884error_clear_mux_table:
885 iio_buffer_demux_free(buffer);
886
887 return ret;
888}
889
890static int iio_update_demux(struct iio_dev *indio_dev)
891{
892 struct iio_buffer *buffer;
893 int ret;
894
895 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
896 ret = iio_buffer_update_demux(indio_dev, buffer);
897 if (ret < 0)
898 goto error_clear_mux_table;
899 }
900 return 0;
901
902error_clear_mux_table:
903 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
904 iio_buffer_demux_free(buffer);
905
906 return ret;
907}
908
909static int iio_enable_buffers(struct iio_dev *indio_dev,
910 struct iio_device_config *config)
911{
912 struct iio_buffer *buffer;
913 int ret;
914
915 indio_dev->active_scan_mask = config->scan_mask;
916 indio_dev->scan_timestamp = config->scan_timestamp;
917 indio_dev->scan_bytes = config->scan_bytes;
918
919 iio_update_demux(indio_dev);
920
921 /* Wind up again */
922 if (indio_dev->setup_ops->preenable) {
923 ret = indio_dev->setup_ops->preenable(indio_dev);
924 if (ret) {
925 dev_dbg(&indio_dev->dev,
926 "Buffer not started: buffer preenable failed (%d)\n", ret);
927 goto err_undo_config;
928 }
929 }
930
931 if (indio_dev->info->update_scan_mode) {
932 ret = indio_dev->info
933 ->update_scan_mode(indio_dev,
934 indio_dev->active_scan_mask);
935 if (ret < 0) {
936 dev_dbg(&indio_dev->dev,
937 "Buffer not started: update scan mode failed (%d)\n",
938 ret);
939 goto err_run_postdisable;
940 }
941 }
942
943 if (indio_dev->info->hwfifo_set_watermark)
944 indio_dev->info->hwfifo_set_watermark(indio_dev,
945 config->watermark);
946
947 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
948 ret = iio_buffer_enable(buffer, indio_dev);
949 if (ret)
950 goto err_disable_buffers;
951 }
952
953 indio_dev->currentmode = config->mode;
954
955 if (indio_dev->setup_ops->postenable) {
956 ret = indio_dev->setup_ops->postenable(indio_dev);
957 if (ret) {
958 dev_dbg(&indio_dev->dev,
959 "Buffer not started: postenable failed (%d)\n", ret);
960 goto err_disable_buffers;
961 }
962 }
963
964 return 0;
965
966err_disable_buffers:
967 list_for_each_entry_continue_reverse(buffer, &indio_dev->buffer_list,
968 buffer_list)
969 iio_buffer_disable(buffer, indio_dev);
970err_run_postdisable:
971 indio_dev->currentmode = INDIO_DIRECT_MODE;
972 if (indio_dev->setup_ops->postdisable)
973 indio_dev->setup_ops->postdisable(indio_dev);
974err_undo_config:
975 indio_dev->active_scan_mask = NULL;
976
977 return ret;
978}
979
980static int iio_disable_buffers(struct iio_dev *indio_dev)
981{
982 struct iio_buffer *buffer;
983 int ret = 0;
984 int ret2;
985
986 /* Wind down existing buffers - iff there are any */
987 if (list_empty(&indio_dev->buffer_list))
988 return 0;
989
990 /*
991 * If things go wrong at some step in disable we still need to continue
992 * to perform the other steps, otherwise we leave the device in a
993 * inconsistent state. We return the error code for the first error we
994 * encountered.
995 */
996
997 if (indio_dev->setup_ops->predisable) {
998 ret2 = indio_dev->setup_ops->predisable(indio_dev);
999 if (ret2 && !ret)
1000 ret = ret2;
1001 }
1002
1003 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1004 ret2 = iio_buffer_disable(buffer, indio_dev);
1005 if (ret2 && !ret)
1006 ret = ret2;
1007 }
1008
1009 indio_dev->currentmode = INDIO_DIRECT_MODE;
1010
1011 if (indio_dev->setup_ops->postdisable) {
1012 ret2 = indio_dev->setup_ops->postdisable(indio_dev);
1013 if (ret2 && !ret)
1014 ret = ret2;
1015 }
1016
1017 iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
1018 indio_dev->active_scan_mask = NULL;
1019
1020 return ret;
1021}
1022
1023static int __iio_update_buffers(struct iio_dev *indio_dev,
1024 struct iio_buffer *insert_buffer,
1025 struct iio_buffer *remove_buffer)
1026{
1027 struct iio_device_config new_config;
1028 int ret;
1029
1030 ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
1031 &new_config);
1032 if (ret)
1033 return ret;
1034
1035 if (insert_buffer) {
1036 ret = iio_buffer_request_update(indio_dev, insert_buffer);
1037 if (ret)
1038 goto err_free_config;
1039 }
1040
1041 ret = iio_disable_buffers(indio_dev);
1042 if (ret)
1043 goto err_deactivate_all;
1044
1045 if (remove_buffer)
1046 iio_buffer_deactivate(remove_buffer);
1047 if (insert_buffer)
1048 iio_buffer_activate(indio_dev, insert_buffer);
1049
1050 /* If no buffers in list, we are done */
1051 if (list_empty(&indio_dev->buffer_list))
1052 return 0;
1053
1054 ret = iio_enable_buffers(indio_dev, &new_config);
1055 if (ret)
1056 goto err_deactivate_all;
1057
1058 return 0;
1059
1060err_deactivate_all:
1061 /*
1062 * We've already verified that the config is valid earlier. If things go
1063 * wrong in either enable or disable the most likely reason is an IO
1064 * error from the device. In this case there is no good recovery
1065 * strategy. Just make sure to disable everything and leave the device
1066 * in a sane state. With a bit of luck the device might come back to
1067 * life again later and userspace can try again.
1068 */
1069 iio_buffer_deactivate_all(indio_dev);
1070
1071err_free_config:
1072 iio_free_scan_mask(indio_dev, new_config.scan_mask);
1073 return ret;
1074}
1075
1076int iio_update_buffers(struct iio_dev *indio_dev,
1077 struct iio_buffer *insert_buffer,
1078 struct iio_buffer *remove_buffer)
1079{
1080 int ret;
1081
1082 if (insert_buffer == remove_buffer)
1083 return 0;
1084
1085 mutex_lock(&indio_dev->info_exist_lock);
1086 mutex_lock(&indio_dev->mlock);
1087
1088 if (insert_buffer && iio_buffer_is_active(insert_buffer))
1089 insert_buffer = NULL;
1090
1091 if (remove_buffer && !iio_buffer_is_active(remove_buffer))
1092 remove_buffer = NULL;
1093
1094 if (!insert_buffer && !remove_buffer) {
1095 ret = 0;
1096 goto out_unlock;
1097 }
1098
1099 if (indio_dev->info == NULL) {
1100 ret = -ENODEV;
1101 goto out_unlock;
1102 }
1103
1104 ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
1105
1106out_unlock:
1107 mutex_unlock(&indio_dev->mlock);
1108 mutex_unlock(&indio_dev->info_exist_lock);
1109
1110 return ret;
1111}
1112EXPORT_SYMBOL_GPL(iio_update_buffers);
1113
1114void iio_disable_all_buffers(struct iio_dev *indio_dev)
1115{
1116 iio_disable_buffers(indio_dev);
1117 iio_buffer_deactivate_all(indio_dev);
1118}
1119
1120static ssize_t iio_buffer_store_enable(struct device *dev,
1121 struct device_attribute *attr,
1122 const char *buf,
1123 size_t len)
1124{
1125 int ret;
1126 bool requested_state;
1127 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1128 bool inlist;
1129
1130 ret = strtobool(buf, &requested_state);
1131 if (ret < 0)
1132 return ret;
1133
1134 mutex_lock(&indio_dev->mlock);
1135
1136 /* Find out if it is in the list */
1137 inlist = iio_buffer_is_active(indio_dev->buffer);
1138 /* Already in desired state */
1139 if (inlist == requested_state)
1140 goto done;
1141
1142 if (requested_state)
1143 ret = __iio_update_buffers(indio_dev,
1144 indio_dev->buffer, NULL);
1145 else
1146 ret = __iio_update_buffers(indio_dev,
1147 NULL, indio_dev->buffer);
1148
1149done:
1150 mutex_unlock(&indio_dev->mlock);
1151 return (ret < 0) ? ret : len;
1152}
1153
1154static const char * const iio_scan_elements_group_name = "scan_elements";
1155
1156static ssize_t iio_buffer_show_watermark(struct device *dev,
1157 struct device_attribute *attr,
1158 char *buf)
1159{
1160 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1161 struct iio_buffer *buffer = indio_dev->buffer;
1162
1163 return sprintf(buf, "%u\n", buffer->watermark);
1164}
1165
1166static ssize_t iio_buffer_store_watermark(struct device *dev,
1167 struct device_attribute *attr,
1168 const char *buf,
1169 size_t len)
1170{
1171 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1172 struct iio_buffer *buffer = indio_dev->buffer;
1173 unsigned int val;
1174 int ret;
1175
1176 ret = kstrtouint(buf, 10, &val);
1177 if (ret)
1178 return ret;
1179 if (!val)
1180 return -EINVAL;
1181
1182 mutex_lock(&indio_dev->mlock);
1183
1184 if (val > buffer->length) {
1185 ret = -EINVAL;
1186 goto out;
1187 }
1188
1189 if (iio_buffer_is_active(indio_dev->buffer)) {
1190 ret = -EBUSY;
1191 goto out;
1192 }
1193
1194 buffer->watermark = val;
1195out:
1196 mutex_unlock(&indio_dev->mlock);
1197
1198 return ret ? ret : len;
1199}
1200
1201static ssize_t iio_dma_show_data_available(struct device *dev,
1202 struct device_attribute *attr,
1203 char *buf)
1204{
1205 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1206 size_t bytes;
1207
1208 bytes = iio_buffer_data_available(indio_dev->buffer);
1209
1210 return sprintf(buf, "%zu\n", bytes);
1211}
1212
1213static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
1214 iio_buffer_write_length);
1215static struct device_attribute dev_attr_length_ro = __ATTR(length,
1216 S_IRUGO, iio_buffer_read_length, NULL);
1217static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
1218 iio_buffer_show_enable, iio_buffer_store_enable);
1219static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
1220 iio_buffer_show_watermark, iio_buffer_store_watermark);
1221static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
1222 S_IRUGO, iio_buffer_show_watermark, NULL);
1223static DEVICE_ATTR(data_available, S_IRUGO,
1224 iio_dma_show_data_available, NULL);
1225
1226static struct attribute *iio_buffer_attrs[] = {
1227 &dev_attr_length.attr,
1228 &dev_attr_enable.attr,
1229 &dev_attr_watermark.attr,
1230 &dev_attr_data_available.attr,
1231};
1232
1233int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
1234{
1235 struct iio_dev_attr *p;
1236 struct attribute **attr;
1237 struct iio_buffer *buffer = indio_dev->buffer;
1238 int ret, i, attrn, attrcount, attrcount_orig = 0;
1239 const struct iio_chan_spec *channels;
1240
1241 channels = indio_dev->channels;
1242 if (channels) {
1243 int ml = indio_dev->masklength;
1244
1245 for (i = 0; i < indio_dev->num_channels; i++)
1246 ml = max(ml, channels[i].scan_index + 1);
1247 indio_dev->masklength = ml;
1248 }
1249
1250 if (!buffer)
1251 return 0;
1252
1253 attrcount = 0;
1254 if (buffer->attrs) {
1255 while (buffer->attrs[attrcount] != NULL)
1256 attrcount++;
1257 }
1258
1259 attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
1260 sizeof(struct attribute *), GFP_KERNEL);
1261 if (!attr)
1262 return -ENOMEM;
1263
1264 memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1265 if (!buffer->access->set_length)
1266 attr[0] = &dev_attr_length_ro.attr;
1267
1268 if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
1269 attr[2] = &dev_attr_watermark_ro.attr;
1270
1271 if (buffer->attrs)
1272 memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
1273 sizeof(struct attribute *) * attrcount);
1274
1275 attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
1276
1277 buffer->buffer_group.name = "buffer";
1278 buffer->buffer_group.attrs = attr;
1279
1280 indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
1281
1282 if (buffer->scan_el_attrs != NULL) {
1283 attr = buffer->scan_el_attrs->attrs;
1284 while (*attr++ != NULL)
1285 attrcount_orig++;
1286 }
1287 attrcount = attrcount_orig;
1288 INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
1289 channels = indio_dev->channels;
1290 if (channels) {
1291 /* new magic */
1292 for (i = 0; i < indio_dev->num_channels; i++) {
1293 if (channels[i].scan_index < 0)
1294 continue;
1295
1296 ret = iio_buffer_add_channel_sysfs(indio_dev,
1297 &channels[i]);
1298 if (ret < 0)
1299 goto error_cleanup_dynamic;
1300 attrcount += ret;
1301 if (channels[i].type == IIO_TIMESTAMP)
1302 indio_dev->scan_index_timestamp =
1303 channels[i].scan_index;
1304 }
1305 if (indio_dev->masklength && buffer->scan_mask == NULL) {
1306 buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
1307 sizeof(*buffer->scan_mask),
1308 GFP_KERNEL);
1309 if (buffer->scan_mask == NULL) {
1310 ret = -ENOMEM;
1311 goto error_cleanup_dynamic;
1312 }
1313 }
1314 }
1315
1316 buffer->scan_el_group.name = iio_scan_elements_group_name;
1317
1318 buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
1319 sizeof(buffer->scan_el_group.attrs[0]),
1320 GFP_KERNEL);
1321 if (buffer->scan_el_group.attrs == NULL) {
1322 ret = -ENOMEM;
1323 goto error_free_scan_mask;
1324 }
1325 if (buffer->scan_el_attrs)
1326 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
1327 sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
1328 attrn = attrcount_orig;
1329
1330 list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
1331 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
1332 indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
1333
1334 return 0;
1335
1336error_free_scan_mask:
1337 kfree(buffer->scan_mask);
1338error_cleanup_dynamic:
1339 iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
1340 kfree(indio_dev->buffer->buffer_group.attrs);
1341
1342 return ret;
1343}
1344
1345void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
1346{
1347 if (!indio_dev->buffer)
1348 return;
1349
1350 kfree(indio_dev->buffer->scan_mask);
1351 kfree(indio_dev->buffer->buffer_group.attrs);
1352 kfree(indio_dev->buffer->scan_el_group.attrs);
1353 iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
1354}
1355
1356/**
1357 * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1358 * @indio_dev: the iio device
1359 * @mask: scan mask to be checked
1360 *
1361 * Return true if exactly one bit is set in the scan mask, false otherwise. It
1362 * can be used for devices where only one channel can be active for sampling at
1363 * a time.
1364 */
1365bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1366 const unsigned long *mask)
1367{
1368 return bitmap_weight(mask, indio_dev->masklength) == 1;
1369}
1370EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1371
1372static const void *iio_demux(struct iio_buffer *buffer,
1373 const void *datain)
1374{
1375 struct iio_demux_table *t;
1376
1377 if (list_empty(&buffer->demux_list))
1378 return datain;
1379 list_for_each_entry(t, &buffer->demux_list, l)
1380 memcpy(buffer->demux_bounce + t->to,
1381 datain + t->from, t->length);
1382
1383 return buffer->demux_bounce;
1384}
1385
1386static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1387{
1388 const void *dataout = iio_demux(buffer, data);
1389 int ret;
1390
1391 ret = buffer->access->store_to(buffer, dataout);
1392 if (ret)
1393 return ret;
1394
1395 /*
1396 * We can't just test for watermark to decide if we wake the poll queue
1397 * because read may request less samples than the watermark.
1398 */
1399 wake_up_interruptible_poll(&buffer->pollq, EPOLLIN | EPOLLRDNORM);
1400 return 0;
1401}
1402
1403/**
1404 * iio_push_to_buffers() - push to a registered buffer.
1405 * @indio_dev: iio_dev structure for device.
1406 * @data: Full scan.
1407 */
1408int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1409{
1410 int ret;
1411 struct iio_buffer *buf;
1412
1413 list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
1414 ret = iio_push_to_buffer(buf, data);
1415 if (ret < 0)
1416 return ret;
1417 }
1418
1419 return 0;
1420}
1421EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1422
1423/**
1424 * iio_buffer_release() - Free a buffer's resources
1425 * @ref: Pointer to the kref embedded in the iio_buffer struct
1426 *
1427 * This function is called when the last reference to the buffer has been
1428 * dropped. It will typically free all resources allocated by the buffer. Do not
1429 * call this function manually, always use iio_buffer_put() when done using a
1430 * buffer.
1431 */
1432static void iio_buffer_release(struct kref *ref)
1433{
1434 struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1435
1436 buffer->access->release(buffer);
1437}
1438
1439/**
1440 * iio_buffer_get() - Grab a reference to the buffer
1441 * @buffer: The buffer to grab a reference for, may be NULL
1442 *
1443 * Returns the pointer to the buffer that was passed into the function.
1444 */
1445struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1446{
1447 if (buffer)
1448 kref_get(&buffer->ref);
1449
1450 return buffer;
1451}
1452EXPORT_SYMBOL_GPL(iio_buffer_get);
1453
1454/**
1455 * iio_buffer_put() - Release the reference to the buffer
1456 * @buffer: The buffer to release the reference for, may be NULL
1457 */
1458void iio_buffer_put(struct iio_buffer *buffer)
1459{
1460 if (buffer)
1461 kref_put(&buffer->ref, iio_buffer_release);
1462}
1463EXPORT_SYMBOL_GPL(iio_buffer_put);
1464
1465/**
1466 * iio_device_attach_buffer - Attach a buffer to a IIO device
1467 * @indio_dev: The device the buffer should be attached to
1468 * @buffer: The buffer to attach to the device
1469 *
1470 * This function attaches a buffer to a IIO device. The buffer stays attached to
1471 * the device until the device is freed. The function should only be called at
1472 * most once per device.
1473 */
1474void iio_device_attach_buffer(struct iio_dev *indio_dev,
1475 struct iio_buffer *buffer)
1476{
1477 indio_dev->buffer = iio_buffer_get(buffer);
1478}
1479EXPORT_SYMBOL_GPL(iio_device_attach_buffer);
1480