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treewide: remove redundant IS_ERR() before error code check
[linux/fpc-iii.git] / drivers / iio / industrialio-buffer.c
blob4ada5592aa2b4824468cee15e3a518ddbb3ba925
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* The industrial I/O core
3 *
4 * Copyright (c) 2008 Jonathan Cameron
5 *
6 * Handling of buffer allocation / resizing.
7 *
8 * Things to look at here.
9 * - Better memory allocation techniques?
10 * - Alternative access techniques?
11 */
12 #include <linux/kernel.h>
13 #include <linux/export.h>
14 #include <linux/device.h>
15 #include <linux/fs.h>
16 #include <linux/cdev.h>
17 #include <linux/slab.h>
18 #include <linux/poll.h>
19 #include <linux/sched/signal.h>
20
21 #include <linux/iio/iio.h>
22 #include "iio_core.h"
23 #include <linux/iio/sysfs.h>
24 #include <linux/iio/buffer.h>
25 #include <linux/iio/buffer_impl.h>
26
27 static const char * const iio_endian_prefix[] = {
28 [IIO_BE] = "be",
29 [IIO_LE] = "le",
30 };
31
32 static bool iio_buffer_is_active(struct iio_buffer *buf)
33 {
34 return !list_empty(&buf->buffer_list);
35 }
36
37 static size_t iio_buffer_data_available(struct iio_buffer *buf)
38 {
39 return buf->access->data_available(buf);
40 }
41
42 static int iio_buffer_flush_hwfifo(struct iio_dev *indio_dev,
43 struct iio_buffer *buf, size_t required)
44 {
45 if (!indio_dev->info->hwfifo_flush_to_buffer)
46 return -ENODEV;
47
48 return indio_dev->info->hwfifo_flush_to_buffer(indio_dev, required);
49 }
50
51 static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
52 size_t to_wait, int to_flush)
53 {
54 size_t avail;
55 int flushed = 0;
56
57 /* wakeup if the device was unregistered */
58 if (!indio_dev->info)
59 return true;
60
61 /* drain the buffer if it was disabled */
62 if (!iio_buffer_is_active(buf)) {
63 to_wait = min_t(size_t, to_wait, 1);
64 to_flush = 0;
65 }
66
67 avail = iio_buffer_data_available(buf);
68
69 if (avail >= to_wait) {
70 /* force a flush for non-blocking reads */
71 if (!to_wait && avail < to_flush)
72 iio_buffer_flush_hwfifo(indio_dev, buf,
73 to_flush - avail);
74 return true;
75 }
76
77 if (to_flush)
78 flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
79 to_wait - avail);
80 if (flushed <= 0)
81 return false;
82
83 if (avail + flushed >= to_wait)
84 return true;
85
86 return false;
87 }
88
89 /**
90 * iio_buffer_read_outer() - chrdev read for buffer access
91 * @filp: File structure pointer for the char device
92 * @buf: Destination buffer for iio buffer read
93 * @n: First n bytes to read
94 * @f_ps: Long offset provided by the user as a seek position
95 *
96 * This function relies on all buffer implementations having an
97 * iio_buffer as their first element.
98 *
99 * Return: negative values corresponding to error codes or ret != 0
100 * for ending the reading activity
101 **/
102 ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
103 size_t n, loff_t *f_ps)
104 {
105 struct iio_dev *indio_dev = filp->private_data;
106 struct iio_buffer *rb = indio_dev->buffer;
107 DEFINE_WAIT_FUNC(wait, woken_wake_function);
108 size_t datum_size;
109 size_t to_wait;
110 int ret = 0;
111
112 if (!indio_dev->info)
113 return -ENODEV;
114
115 if (!rb || !rb->access->read)
116 return -EINVAL;
117
118 datum_size = rb->bytes_per_datum;
119
120 /*
121 * If datum_size is 0 there will never be anything to read from the
122 * buffer, so signal end of file now.
123 */
124 if (!datum_size)
125 return 0;
126
127 if (filp->f_flags & O_NONBLOCK)
128 to_wait = 0;
129 else
130 to_wait = min_t(size_t, n / datum_size, rb->watermark);
131
132 add_wait_queue(&rb->pollq, &wait);
133 do {
134 if (!indio_dev->info) {
135 ret = -ENODEV;
136 break;
137 }
138
139 if (!iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size)) {
140 if (signal_pending(current)) {
141 ret = -ERESTARTSYS;
142 break;
143 }
144
145 wait_woken(&wait, TASK_INTERRUPTIBLE,
146 MAX_SCHEDULE_TIMEOUT);
147 continue;
148 }
149
150 ret = rb->access->read(rb, n, buf);
151 if (ret == 0 && (filp->f_flags & O_NONBLOCK))
152 ret = -EAGAIN;
153 } while (ret == 0);
154 remove_wait_queue(&rb->pollq, &wait);
155
156 return ret;
157 }
158
159 /**
160 * iio_buffer_poll() - poll the buffer to find out if it has data
161 * @filp: File structure pointer for device access
162 * @wait: Poll table structure pointer for which the driver adds
163 * a wait queue
164 *
165 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
166 * or 0 for other cases
167 */
168 __poll_t iio_buffer_poll(struct file *filp,
169 struct poll_table_struct *wait)
170 {
171 struct iio_dev *indio_dev = filp->private_data;
172 struct iio_buffer *rb = indio_dev->buffer;
173
174 if (!indio_dev->info || rb == NULL)
175 return 0;
176
177 poll_wait(filp, &rb->pollq, wait);
178 if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0))
179 return EPOLLIN | EPOLLRDNORM;
180 return 0;
181 }
182
183 /**
184 * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
185 * @indio_dev: The IIO device
186 *
187 * Wakes up the event waitqueue used for poll(). Should usually
188 * be called when the device is unregistered.
189 */
190 void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
191 {
192 if (!indio_dev->buffer)
193 return;
194
195 wake_up(&indio_dev->buffer->pollq);
196 }
197
198 void iio_buffer_init(struct iio_buffer *buffer)
199 {
200 INIT_LIST_HEAD(&buffer->demux_list);
201 INIT_LIST_HEAD(&buffer->buffer_list);
202 init_waitqueue_head(&buffer->pollq);
203 kref_init(&buffer->ref);
204 if (!buffer->watermark)
205 buffer->watermark = 1;
206 }
207 EXPORT_SYMBOL(iio_buffer_init);
208
209 /**
210 * iio_buffer_set_attrs - Set buffer specific attributes
211 * @buffer: The buffer for which we are setting attributes
212 * @attrs: Pointer to a null terminated list of pointers to attributes
213 */
214 void iio_buffer_set_attrs(struct iio_buffer *buffer,
215 const struct attribute **attrs)
216 {
217 buffer->attrs = attrs;
218 }
219 EXPORT_SYMBOL_GPL(iio_buffer_set_attrs);
220
221 static ssize_t iio_show_scan_index(struct device *dev,
222 struct device_attribute *attr,
223 char *buf)
224 {
225 return sprintf(buf, "%u\n", to_iio_dev_attr(attr)->c->scan_index);
226 }
227
228 static ssize_t iio_show_fixed_type(struct device *dev,
229 struct device_attribute *attr,
230 char *buf)
231 {
232 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
233 u8 type = this_attr->c->scan_type.endianness;
234
235 if (type == IIO_CPU) {
236 #ifdef __LITTLE_ENDIAN
237 type = IIO_LE;
238 #else
239 type = IIO_BE;
240 #endif
241 }
242 if (this_attr->c->scan_type.repeat > 1)
243 return sprintf(buf, "%s:%c%d/%dX%d>>%u\n",
244 iio_endian_prefix[type],
245 this_attr->c->scan_type.sign,
246 this_attr->c->scan_type.realbits,
247 this_attr->c->scan_type.storagebits,
248 this_attr->c->scan_type.repeat,
249 this_attr->c->scan_type.shift);
250 else
251 return sprintf(buf, "%s:%c%d/%d>>%u\n",
252 iio_endian_prefix[type],
253 this_attr->c->scan_type.sign,
254 this_attr->c->scan_type.realbits,
255 this_attr->c->scan_type.storagebits,
256 this_attr->c->scan_type.shift);
257 }
258
259 static ssize_t iio_scan_el_show(struct device *dev,
260 struct device_attribute *attr,
261 char *buf)
262 {
263 int ret;
264 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
265
266 /* Ensure ret is 0 or 1. */
267 ret = !!test_bit(to_iio_dev_attr(attr)->address,
268 indio_dev->buffer->scan_mask);
269
270 return sprintf(buf, "%d\n", ret);
271 }
272
273 /* Note NULL used as error indicator as it doesn't make sense. */
274 static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
275 unsigned int masklength,
276 const unsigned long *mask,
277 bool strict)
278 {
279 if (bitmap_empty(mask, masklength))
280 return NULL;
281 while (*av_masks) {
282 if (strict) {
283 if (bitmap_equal(mask, av_masks, masklength))
284 return av_masks;
285 } else {
286 if (bitmap_subset(mask, av_masks, masklength))
287 return av_masks;
288 }
289 av_masks += BITS_TO_LONGS(masklength);
290 }
291 return NULL;
292 }
293
294 static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
295 const unsigned long *mask)
296 {
297 if (!indio_dev->setup_ops->validate_scan_mask)
298 return true;
299
300 return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
301 }
302
303 /**
304 * iio_scan_mask_set() - set particular bit in the scan mask
305 * @indio_dev: the iio device
306 * @buffer: the buffer whose scan mask we are interested in
307 * @bit: the bit to be set.
308 *
309 * Note that at this point we have no way of knowing what other
310 * buffers might request, hence this code only verifies that the
311 * individual buffers request is plausible.
312 */
313 static int iio_scan_mask_set(struct iio_dev *indio_dev,
314 struct iio_buffer *buffer, int bit)
315 {
316 const unsigned long *mask;
317 unsigned long *trialmask;
318
319 trialmask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
320 sizeof(*trialmask), GFP_KERNEL);
321 if (trialmask == NULL)
322 return -ENOMEM;
323 if (!indio_dev->masklength) {
324 WARN(1, "Trying to set scanmask prior to registering buffer\n");
325 goto err_invalid_mask;
326 }
327 bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
328 set_bit(bit, trialmask);
329
330 if (!iio_validate_scan_mask(indio_dev, trialmask))
331 goto err_invalid_mask;
332
333 if (indio_dev->available_scan_masks) {
334 mask = iio_scan_mask_match(indio_dev->available_scan_masks,
335 indio_dev->masklength,
336 trialmask, false);
337 if (!mask)
338 goto err_invalid_mask;
339 }
340 bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
341
342 bitmap_free(trialmask);
343
344 return 0;
345
346 err_invalid_mask:
347 bitmap_free(trialmask);
348 return -EINVAL;
349 }
350
351 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
352 {
353 clear_bit(bit, buffer->scan_mask);
354 return 0;
355 }
356
357 static int iio_scan_mask_query(struct iio_dev *indio_dev,
358 struct iio_buffer *buffer, int bit)
359 {
360 if (bit > indio_dev->masklength)
361 return -EINVAL;
362
363 if (!buffer->scan_mask)
364 return 0;
365
366 /* Ensure return value is 0 or 1. */
367 return !!test_bit(bit, buffer->scan_mask);
368 };
369
370 static ssize_t iio_scan_el_store(struct device *dev,
371 struct device_attribute *attr,
372 const char *buf,
373 size_t len)
374 {
375 int ret;
376 bool state;
377 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
378 struct iio_buffer *buffer = indio_dev->buffer;
379 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
380
381 ret = strtobool(buf, &state);
382 if (ret < 0)
383 return ret;
384 mutex_lock(&indio_dev->mlock);
385 if (iio_buffer_is_active(indio_dev->buffer)) {
386 ret = -EBUSY;
387 goto error_ret;
388 }
389 ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
390 if (ret < 0)
391 goto error_ret;
392 if (!state && ret) {
393 ret = iio_scan_mask_clear(buffer, this_attr->address);
394 if (ret)
395 goto error_ret;
396 } else if (state && !ret) {
397 ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
398 if (ret)
399 goto error_ret;
400 }
401
402 error_ret:
403 mutex_unlock(&indio_dev->mlock);
404
405 return ret < 0 ? ret : len;
406
407 }
408
409 static ssize_t iio_scan_el_ts_show(struct device *dev,
410 struct device_attribute *attr,
411 char *buf)
412 {
413 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
414 return sprintf(buf, "%d\n", indio_dev->buffer->scan_timestamp);
415 }
416
417 static ssize_t iio_scan_el_ts_store(struct device *dev,
418 struct device_attribute *attr,
419 const char *buf,
420 size_t len)
421 {
422 int ret;
423 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
424 bool state;
425
426 ret = strtobool(buf, &state);
427 if (ret < 0)
428 return ret;
429
430 mutex_lock(&indio_dev->mlock);
431 if (iio_buffer_is_active(indio_dev->buffer)) {
432 ret = -EBUSY;
433 goto error_ret;
434 }
435 indio_dev->buffer->scan_timestamp = state;
436 error_ret:
437 mutex_unlock(&indio_dev->mlock);
438
439 return ret ? ret : len;
440 }
441
442 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
443 const struct iio_chan_spec *chan)
444 {
445 int ret, attrcount = 0;
446 struct iio_buffer *buffer = indio_dev->buffer;
447
448 ret = __iio_add_chan_devattr("index",
449 chan,
450 &iio_show_scan_index,
451 NULL,
452 0,
453 IIO_SEPARATE,
454 &indio_dev->dev,
455 &buffer->scan_el_dev_attr_list);
456 if (ret)
457 return ret;
458 attrcount++;
459 ret = __iio_add_chan_devattr("type",
460 chan,
461 &iio_show_fixed_type,
462 NULL,
463 0,
464 0,
465 &indio_dev->dev,
466 &buffer->scan_el_dev_attr_list);
467 if (ret)
468 return ret;
469 attrcount++;
470 if (chan->type != IIO_TIMESTAMP)
471 ret = __iio_add_chan_devattr("en",
472 chan,
473 &iio_scan_el_show,
474 &iio_scan_el_store,
475 chan->scan_index,
476 0,
477 &indio_dev->dev,
478 &buffer->scan_el_dev_attr_list);
479 else
480 ret = __iio_add_chan_devattr("en",
481 chan,
482 &iio_scan_el_ts_show,
483 &iio_scan_el_ts_store,
484 chan->scan_index,
485 0,
486 &indio_dev->dev,
487 &buffer->scan_el_dev_attr_list);
488 if (ret)
489 return ret;
490 attrcount++;
491 ret = attrcount;
492 return ret;
493 }
494
495 static ssize_t iio_buffer_read_length(struct device *dev,
496 struct device_attribute *attr,
497 char *buf)
498 {
499 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
500 struct iio_buffer *buffer = indio_dev->buffer;
501
502 return sprintf(buf, "%d\n", buffer->length);
503 }
504
505 static ssize_t iio_buffer_write_length(struct device *dev,
506 struct device_attribute *attr,
507 const char *buf, size_t len)
508 {
509 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
510 struct iio_buffer *buffer = indio_dev->buffer;
511 unsigned int val;
512 int ret;
513
514 ret = kstrtouint(buf, 10, &val);
515 if (ret)
516 return ret;
517
518 if (val == buffer->length)
519 return len;
520
521 mutex_lock(&indio_dev->mlock);
522 if (iio_buffer_is_active(indio_dev->buffer)) {
523 ret = -EBUSY;
524 } else {
525 buffer->access->set_length(buffer, val);
526 ret = 0;
527 }
528 if (ret)
529 goto out;
530 if (buffer->length && buffer->length < buffer->watermark)
531 buffer->watermark = buffer->length;
532 out:
533 mutex_unlock(&indio_dev->mlock);
534
535 return ret ? ret : len;
536 }
537
538 static ssize_t iio_buffer_show_enable(struct device *dev,
539 struct device_attribute *attr,
540 char *buf)
541 {
542 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
543 return sprintf(buf, "%d\n", iio_buffer_is_active(indio_dev->buffer));
544 }
545
546 static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
547 unsigned int scan_index)
548 {
549 const struct iio_chan_spec *ch;
550 unsigned int bytes;
551
552 ch = iio_find_channel_from_si(indio_dev, scan_index);
553 bytes = ch->scan_type.storagebits / 8;
554 if (ch->scan_type.repeat > 1)
555 bytes *= ch->scan_type.repeat;
556 return bytes;
557 }
558
559 static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
560 {
561 return iio_storage_bytes_for_si(indio_dev,
562 indio_dev->scan_index_timestamp);
563 }
564
565 static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
566 const unsigned long *mask, bool timestamp)
567 {
568 unsigned bytes = 0;
569 int length, i, largest = 0;
570
571 /* How much space will the demuxed element take? */
572 for_each_set_bit(i, mask,
573 indio_dev->masklength) {
574 length = iio_storage_bytes_for_si(indio_dev, i);
575 bytes = ALIGN(bytes, length);
576 bytes += length;
577 largest = max(largest, length);
578 }
579
580 if (timestamp) {
581 length = iio_storage_bytes_for_timestamp(indio_dev);
582 bytes = ALIGN(bytes, length);
583 bytes += length;
584 largest = max(largest, length);
585 }
586
587 bytes = ALIGN(bytes, largest);
588 return bytes;
589 }
590
591 static void iio_buffer_activate(struct iio_dev *indio_dev,
592 struct iio_buffer *buffer)
593 {
594 iio_buffer_get(buffer);
595 list_add(&buffer->buffer_list, &indio_dev->buffer_list);
596 }
597
598 static void iio_buffer_deactivate(struct iio_buffer *buffer)
599 {
600 list_del_init(&buffer->buffer_list);
601 wake_up_interruptible(&buffer->pollq);
602 iio_buffer_put(buffer);
603 }
604
605 static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
606 {
607 struct iio_buffer *buffer, *_buffer;
608
609 list_for_each_entry_safe(buffer, _buffer,
610 &indio_dev->buffer_list, buffer_list)
611 iio_buffer_deactivate(buffer);
612 }
613
614 static int iio_buffer_enable(struct iio_buffer *buffer,
615 struct iio_dev *indio_dev)
616 {
617 if (!buffer->access->enable)
618 return 0;
619 return buffer->access->enable(buffer, indio_dev);
620 }
621
622 static int iio_buffer_disable(struct iio_buffer *buffer,
623 struct iio_dev *indio_dev)
624 {
625 if (!buffer->access->disable)
626 return 0;
627 return buffer->access->disable(buffer, indio_dev);
628 }
629
630 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
631 struct iio_buffer *buffer)
632 {
633 unsigned int bytes;
634
635 if (!buffer->access->set_bytes_per_datum)
636 return;
637
638 bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
639 buffer->scan_timestamp);
640
641 buffer->access->set_bytes_per_datum(buffer, bytes);
642 }
643
644 static int iio_buffer_request_update(struct iio_dev *indio_dev,
645 struct iio_buffer *buffer)
646 {
647 int ret;
648
649 iio_buffer_update_bytes_per_datum(indio_dev, buffer);
650 if (buffer->access->request_update) {
651 ret = buffer->access->request_update(buffer);
652 if (ret) {
653 dev_dbg(&indio_dev->dev,
654 "Buffer not started: buffer parameter update failed (%d)\n",
655 ret);
656 return ret;
657 }
658 }
659
660 return 0;
661 }
662
663 static void iio_free_scan_mask(struct iio_dev *indio_dev,
664 const unsigned long *mask)
665 {
666 /* If the mask is dynamically allocated free it, otherwise do nothing */
667 if (!indio_dev->available_scan_masks)
668 bitmap_free(mask);
669 }
670
671 struct iio_device_config {
672 unsigned int mode;
673 unsigned int watermark;
674 const unsigned long *scan_mask;
675 unsigned int scan_bytes;
676 bool scan_timestamp;
677 };
678
679 static int iio_verify_update(struct iio_dev *indio_dev,
680 struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
681 struct iio_device_config *config)
682 {
683 unsigned long *compound_mask;
684 const unsigned long *scan_mask;
685 bool strict_scanmask = false;
686 struct iio_buffer *buffer;
687 bool scan_timestamp;
688 unsigned int modes;
689
690 memset(config, 0, sizeof(*config));
691 config->watermark = ~0;
692
693 /*
694 * If there is just one buffer and we are removing it there is nothing
695 * to verify.
696 */
697 if (remove_buffer && !insert_buffer &&
698 list_is_singular(&indio_dev->buffer_list))
699 return 0;
700
701 modes = indio_dev->modes;
702
703 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
704 if (buffer == remove_buffer)
705 continue;
706 modes &= buffer->access->modes;
707 config->watermark = min(config->watermark, buffer->watermark);
708 }
709
710 if (insert_buffer) {
711 modes &= insert_buffer->access->modes;
712 config->watermark = min(config->watermark,
713 insert_buffer->watermark);
714 }
715
716 /* Definitely possible for devices to support both of these. */
717 if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
718 config->mode = INDIO_BUFFER_TRIGGERED;
719 } else if (modes & INDIO_BUFFER_HARDWARE) {
720 /*
721 * Keep things simple for now and only allow a single buffer to
722 * be connected in hardware mode.
723 */
724 if (insert_buffer && !list_empty(&indio_dev->buffer_list))
725 return -EINVAL;
726 config->mode = INDIO_BUFFER_HARDWARE;
727 strict_scanmask = true;
728 } else if (modes & INDIO_BUFFER_SOFTWARE) {
729 config->mode = INDIO_BUFFER_SOFTWARE;
730 } else {
731 /* Can only occur on first buffer */
732 if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
733 dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
734 return -EINVAL;
735 }
736
737 /* What scan mask do we actually have? */
738 compound_mask = bitmap_zalloc(indio_dev->masklength, GFP_KERNEL);
739 if (compound_mask == NULL)
740 return -ENOMEM;
741
742 scan_timestamp = false;
743
744 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
745 if (buffer == remove_buffer)
746 continue;
747 bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
748 indio_dev->masklength);
749 scan_timestamp |= buffer->scan_timestamp;
750 }
751
752 if (insert_buffer) {
753 bitmap_or(compound_mask, compound_mask,
754 insert_buffer->scan_mask, indio_dev->masklength);
755 scan_timestamp |= insert_buffer->scan_timestamp;
756 }
757
758 if (indio_dev->available_scan_masks) {
759 scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
760 indio_dev->masklength,
761 compound_mask,
762 strict_scanmask);
763 bitmap_free(compound_mask);
764 if (scan_mask == NULL)
765 return -EINVAL;
766 } else {
767 scan_mask = compound_mask;
768 }
769
770 config->scan_bytes = iio_compute_scan_bytes(indio_dev,
771 scan_mask, scan_timestamp);
772 config->scan_mask = scan_mask;
773 config->scan_timestamp = scan_timestamp;
774
775 return 0;
776 }
777
778 /**
779 * struct iio_demux_table - table describing demux memcpy ops
780 * @from: index to copy from
781 * @to: index to copy to
782 * @length: how many bytes to copy
783 * @l: list head used for management
784 */
785 struct iio_demux_table {
786 unsigned from;
787 unsigned to;
788 unsigned length;
789 struct list_head l;
790 };
791
792 static void iio_buffer_demux_free(struct iio_buffer *buffer)
793 {
794 struct iio_demux_table *p, *q;
795 list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
796 list_del(&p->l);
797 kfree(p);
798 }
799 }
800
801 static int iio_buffer_add_demux(struct iio_buffer *buffer,
802 struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
803 unsigned int length)
804 {
805
806 if (*p && (*p)->from + (*p)->length == in_loc &&
807 (*p)->to + (*p)->length == out_loc) {
808 (*p)->length += length;
809 } else {
810 *p = kmalloc(sizeof(**p), GFP_KERNEL);
811 if (*p == NULL)
812 return -ENOMEM;
813 (*p)->from = in_loc;
814 (*p)->to = out_loc;
815 (*p)->length = length;
816 list_add_tail(&(*p)->l, &buffer->demux_list);
817 }
818
819 return 0;
820 }
821
822 static int iio_buffer_update_demux(struct iio_dev *indio_dev,
823 struct iio_buffer *buffer)
824 {
825 int ret, in_ind = -1, out_ind, length;
826 unsigned in_loc = 0, out_loc = 0;
827 struct iio_demux_table *p = NULL;
828
829 /* Clear out any old demux */
830 iio_buffer_demux_free(buffer);
831 kfree(buffer->demux_bounce);
832 buffer->demux_bounce = NULL;
833
834 /* First work out which scan mode we will actually have */
835 if (bitmap_equal(indio_dev->active_scan_mask,
836 buffer->scan_mask,
837 indio_dev->masklength))
838 return 0;
839
840 /* Now we have the two masks, work from least sig and build up sizes */
841 for_each_set_bit(out_ind,
842 buffer->scan_mask,
843 indio_dev->masklength) {
844 in_ind = find_next_bit(indio_dev->active_scan_mask,
845 indio_dev->masklength,
846 in_ind + 1);
847 while (in_ind != out_ind) {
848 in_ind = find_next_bit(indio_dev->active_scan_mask,
849 indio_dev->masklength,
850 in_ind + 1);
851 length = iio_storage_bytes_for_si(indio_dev, in_ind);
852 /* Make sure we are aligned */
853 in_loc = roundup(in_loc, length) + length;
854 }
855 length = iio_storage_bytes_for_si(indio_dev, in_ind);
856 out_loc = roundup(out_loc, length);
857 in_loc = roundup(in_loc, length);
858 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
859 if (ret)
860 goto error_clear_mux_table;
861 out_loc += length;
862 in_loc += length;
863 }
864 /* Relies on scan_timestamp being last */
865 if (buffer->scan_timestamp) {
866 length = iio_storage_bytes_for_timestamp(indio_dev);
867 out_loc = roundup(out_loc, length);
868 in_loc = roundup(in_loc, length);
869 ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
870 if (ret)
871 goto error_clear_mux_table;
872 out_loc += length;
873 in_loc += length;
874 }
875 buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
876 if (buffer->demux_bounce == NULL) {
877 ret = -ENOMEM;
878 goto error_clear_mux_table;
879 }
880 return 0;
881
882 error_clear_mux_table:
883 iio_buffer_demux_free(buffer);
884
885 return ret;
886 }
887
888 static int iio_update_demux(struct iio_dev *indio_dev)
889 {
890 struct iio_buffer *buffer;
891 int ret;
892
893 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
894 ret = iio_buffer_update_demux(indio_dev, buffer);
895 if (ret < 0)
896 goto error_clear_mux_table;
897 }
898 return 0;
899
900 error_clear_mux_table:
901 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
902 iio_buffer_demux_free(buffer);
903
904 return ret;
905 }
906
907 static int iio_enable_buffers(struct iio_dev *indio_dev,
908 struct iio_device_config *config)
909 {
910 struct iio_buffer *buffer;
911 int ret;
912
913 indio_dev->active_scan_mask = config->scan_mask;
914 indio_dev->scan_timestamp = config->scan_timestamp;
915 indio_dev->scan_bytes = config->scan_bytes;
916
917 iio_update_demux(indio_dev);
918
919 /* Wind up again */
920 if (indio_dev->setup_ops->preenable) {
921 ret = indio_dev->setup_ops->preenable(indio_dev);
922 if (ret) {
923 dev_dbg(&indio_dev->dev,
924 "Buffer not started: buffer preenable failed (%d)\n", ret);
925 goto err_undo_config;
926 }
927 }
928
929 if (indio_dev->info->update_scan_mode) {
930 ret = indio_dev->info
931 ->update_scan_mode(indio_dev,
932 indio_dev->active_scan_mask);
933 if (ret < 0) {
934 dev_dbg(&indio_dev->dev,
935 "Buffer not started: update scan mode failed (%d)\n",
936 ret);
937 goto err_run_postdisable;
938 }
939 }
940
941 if (indio_dev->info->hwfifo_set_watermark)
942 indio_dev->info->hwfifo_set_watermark(indio_dev,
943 config->watermark);
944
945 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
946 ret = iio_buffer_enable(buffer, indio_dev);
947 if (ret)
948 goto err_disable_buffers;
949 }
950
951 indio_dev->currentmode = config->mode;
952
953 if (indio_dev->setup_ops->postenable) {
954 ret = indio_dev->setup_ops->postenable(indio_dev);
955 if (ret) {
956 dev_dbg(&indio_dev->dev,
957 "Buffer not started: postenable failed (%d)\n", ret);
958 goto err_disable_buffers;
959 }
960 }
961
962 return 0;
963
964 err_disable_buffers:
965 list_for_each_entry_continue_reverse(buffer, &indio_dev->buffer_list,
966 buffer_list)
967 iio_buffer_disable(buffer, indio_dev);
968 err_run_postdisable:
969 indio_dev->currentmode = INDIO_DIRECT_MODE;
970 if (indio_dev->setup_ops->postdisable)
971 indio_dev->setup_ops->postdisable(indio_dev);
972 err_undo_config:
973 indio_dev->active_scan_mask = NULL;
974
975 return ret;
976 }
977
978 static int iio_disable_buffers(struct iio_dev *indio_dev)
979 {
980 struct iio_buffer *buffer;
981 int ret = 0;
982 int ret2;
983
984 /* Wind down existing buffers - iff there are any */
985 if (list_empty(&indio_dev->buffer_list))
986 return 0;
987
988 /*
989 * If things go wrong at some step in disable we still need to continue
990 * to perform the other steps, otherwise we leave the device in a
991 * inconsistent state. We return the error code for the first error we
992 * encountered.
993 */
994
995 if (indio_dev->setup_ops->predisable) {
996 ret2 = indio_dev->setup_ops->predisable(indio_dev);
997 if (ret2 && !ret)
998 ret = ret2;
999 }
1000
1001 list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
1002 ret2 = iio_buffer_disable(buffer, indio_dev);
1003 if (ret2 && !ret)
1004 ret = ret2;
1005 }
1006
1007 indio_dev->currentmode = INDIO_DIRECT_MODE;
1008
1009 if (indio_dev->setup_ops->postdisable) {
1010 ret2 = indio_dev->setup_ops->postdisable(indio_dev);
1011 if (ret2 && !ret)
1012 ret = ret2;
1013 }
1014
1015 iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
1016 indio_dev->active_scan_mask = NULL;
1017
1018 return ret;
1019 }
1020
1021 static int __iio_update_buffers(struct iio_dev *indio_dev,
1022 struct iio_buffer *insert_buffer,
1023 struct iio_buffer *remove_buffer)
1024 {
1025 struct iio_device_config new_config;
1026 int ret;
1027
1028 ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
1029 &new_config);
1030 if (ret)
1031 return ret;
1032
1033 if (insert_buffer) {
1034 ret = iio_buffer_request_update(indio_dev, insert_buffer);
1035 if (ret)
1036 goto err_free_config;
1037 }
1038
1039 ret = iio_disable_buffers(indio_dev);
1040 if (ret)
1041 goto err_deactivate_all;
1042
1043 if (remove_buffer)
1044 iio_buffer_deactivate(remove_buffer);
1045 if (insert_buffer)
1046 iio_buffer_activate(indio_dev, insert_buffer);
1047
1048 /* If no buffers in list, we are done */
1049 if (list_empty(&indio_dev->buffer_list))
1050 return 0;
1051
1052 ret = iio_enable_buffers(indio_dev, &new_config);
1053 if (ret)
1054 goto err_deactivate_all;
1055
1056 return 0;
1057
1058 err_deactivate_all:
1059 /*
1060 * We've already verified that the config is valid earlier. If things go
1061 * wrong in either enable or disable the most likely reason is an IO
1062 * error from the device. In this case there is no good recovery
1063 * strategy. Just make sure to disable everything and leave the device
1064 * in a sane state. With a bit of luck the device might come back to
1065 * life again later and userspace can try again.
1066 */
1067 iio_buffer_deactivate_all(indio_dev);
1068
1069 err_free_config:
1070 iio_free_scan_mask(indio_dev, new_config.scan_mask);
1071 return ret;
1072 }
1073
1074 int iio_update_buffers(struct iio_dev *indio_dev,
1075 struct iio_buffer *insert_buffer,
1076 struct iio_buffer *remove_buffer)
1077 {
1078 int ret;
1079
1080 if (insert_buffer == remove_buffer)
1081 return 0;
1082
1083 mutex_lock(&indio_dev->info_exist_lock);
1084 mutex_lock(&indio_dev->mlock);
1085
1086 if (insert_buffer && iio_buffer_is_active(insert_buffer))
1087 insert_buffer = NULL;
1088
1089 if (remove_buffer && !iio_buffer_is_active(remove_buffer))
1090 remove_buffer = NULL;
1091
1092 if (!insert_buffer && !remove_buffer) {
1093 ret = 0;
1094 goto out_unlock;
1095 }
1096
1097 if (indio_dev->info == NULL) {
1098 ret = -ENODEV;
1099 goto out_unlock;
1100 }
1101
1102 ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
1103
1104 out_unlock:
1105 mutex_unlock(&indio_dev->mlock);
1106 mutex_unlock(&indio_dev->info_exist_lock);
1107
1108 return ret;
1109 }
1110 EXPORT_SYMBOL_GPL(iio_update_buffers);
1111
1112 void iio_disable_all_buffers(struct iio_dev *indio_dev)
1113 {
1114 iio_disable_buffers(indio_dev);
1115 iio_buffer_deactivate_all(indio_dev);
1116 }
1117
1118 static ssize_t iio_buffer_store_enable(struct device *dev,
1119 struct device_attribute *attr,
1120 const char *buf,
1121 size_t len)
1122 {
1123 int ret;
1124 bool requested_state;
1125 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1126 bool inlist;
1127
1128 ret = strtobool(buf, &requested_state);
1129 if (ret < 0)
1130 return ret;
1131
1132 mutex_lock(&indio_dev->mlock);
1133
1134 /* Find out if it is in the list */
1135 inlist = iio_buffer_is_active(indio_dev->buffer);
1136 /* Already in desired state */
1137 if (inlist == requested_state)
1138 goto done;
1139
1140 if (requested_state)
1141 ret = __iio_update_buffers(indio_dev,
1142 indio_dev->buffer, NULL);
1143 else
1144 ret = __iio_update_buffers(indio_dev,
1145 NULL, indio_dev->buffer);
1146
1147 done:
1148 mutex_unlock(&indio_dev->mlock);
1149 return (ret < 0) ? ret : len;
1150 }
1151
1152 static const char * const iio_scan_elements_group_name = "scan_elements";
1153
1154 static ssize_t iio_buffer_show_watermark(struct device *dev,
1155 struct device_attribute *attr,
1156 char *buf)
1157 {
1158 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1159 struct iio_buffer *buffer = indio_dev->buffer;
1160
1161 return sprintf(buf, "%u\n", buffer->watermark);
1162 }
1163
1164 static ssize_t iio_buffer_store_watermark(struct device *dev,
1165 struct device_attribute *attr,
1166 const char *buf,
1167 size_t len)
1168 {
1169 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1170 struct iio_buffer *buffer = indio_dev->buffer;
1171 unsigned int val;
1172 int ret;
1173
1174 ret = kstrtouint(buf, 10, &val);
1175 if (ret)
1176 return ret;
1177 if (!val)
1178 return -EINVAL;
1179
1180 mutex_lock(&indio_dev->mlock);
1181
1182 if (val > buffer->length) {
1183 ret = -EINVAL;
1184 goto out;
1185 }
1186
1187 if (iio_buffer_is_active(indio_dev->buffer)) {
1188 ret = -EBUSY;
1189 goto out;
1190 }
1191
1192 buffer->watermark = val;
1193 out:
1194 mutex_unlock(&indio_dev->mlock);
1195
1196 return ret ? ret : len;
1197 }
1198
1199 static ssize_t iio_dma_show_data_available(struct device *dev,
1200 struct device_attribute *attr,
1201 char *buf)
1202 {
1203 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1204 size_t bytes;
1205
1206 bytes = iio_buffer_data_available(indio_dev->buffer);
1207
1208 return sprintf(buf, "%zu\n", bytes);
1209 }
1210
1211 static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
1212 iio_buffer_write_length);
1213 static struct device_attribute dev_attr_length_ro = __ATTR(length,
1214 S_IRUGO, iio_buffer_read_length, NULL);
1215 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
1216 iio_buffer_show_enable, iio_buffer_store_enable);
1217 static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
1218 iio_buffer_show_watermark, iio_buffer_store_watermark);
1219 static struct device_attribute dev_attr_watermark_ro = __ATTR(watermark,
1220 S_IRUGO, iio_buffer_show_watermark, NULL);
1221 static DEVICE_ATTR(data_available, S_IRUGO,
1222 iio_dma_show_data_available, NULL);
1223
1224 static struct attribute *iio_buffer_attrs[] = {
1225 &dev_attr_length.attr,
1226 &dev_attr_enable.attr,
1227 &dev_attr_watermark.attr,
1228 &dev_attr_data_available.attr,
1229 };
1230
1231 int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
1232 {
1233 struct iio_dev_attr *p;
1234 struct attribute **attr;
1235 struct iio_buffer *buffer = indio_dev->buffer;
1236 int ret, i, attrn, attrcount, attrcount_orig = 0;
1237 const struct iio_chan_spec *channels;
1238
1239 channels = indio_dev->channels;
1240 if (channels) {
1241 int ml = indio_dev->masklength;
1242
1243 for (i = 0; i < indio_dev->num_channels; i++)
1244 ml = max(ml, channels[i].scan_index + 1);
1245 indio_dev->masklength = ml;
1246 }
1247
1248 if (!buffer)
1249 return 0;
1250
1251 attrcount = 0;
1252 if (buffer->attrs) {
1253 while (buffer->attrs[attrcount] != NULL)
1254 attrcount++;
1255 }
1256
1257 attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
1258 sizeof(struct attribute *), GFP_KERNEL);
1259 if (!attr)
1260 return -ENOMEM;
1261
1262 memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1263 if (!buffer->access->set_length)
1264 attr[0] = &dev_attr_length_ro.attr;
1265
1266 if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
1267 attr[2] = &dev_attr_watermark_ro.attr;
1268
1269 if (buffer->attrs)
1270 memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
1271 sizeof(struct attribute *) * attrcount);
1272
1273 attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
1274
1275 buffer->buffer_group.name = "buffer";
1276 buffer->buffer_group.attrs = attr;
1277
1278 indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
1279
1280 if (buffer->scan_el_attrs != NULL) {
1281 attr = buffer->scan_el_attrs->attrs;
1282 while (*attr++ != NULL)
1283 attrcount_orig++;
1284 }
1285 attrcount = attrcount_orig;
1286 INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
1287 channels = indio_dev->channels;
1288 if (channels) {
1289 /* new magic */
1290 for (i = 0; i < indio_dev->num_channels; i++) {
1291 if (channels[i].scan_index < 0)
1292 continue;
1293
1294 ret = iio_buffer_add_channel_sysfs(indio_dev,
1295 &channels[i]);
1296 if (ret < 0)
1297 goto error_cleanup_dynamic;
1298 attrcount += ret;
1299 if (channels[i].type == IIO_TIMESTAMP)
1300 indio_dev->scan_index_timestamp =
1301 channels[i].scan_index;
1302 }
1303 if (indio_dev->masklength && buffer->scan_mask == NULL) {
1304 buffer->scan_mask = bitmap_zalloc(indio_dev->masklength,
1305 GFP_KERNEL);
1306 if (buffer->scan_mask == NULL) {
1307 ret = -ENOMEM;
1308 goto error_cleanup_dynamic;
1309 }
1310 }
1311 }
1312
1313 buffer->scan_el_group.name = iio_scan_elements_group_name;
1314
1315 buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
1316 sizeof(buffer->scan_el_group.attrs[0]),
1317 GFP_KERNEL);
1318 if (buffer->scan_el_group.attrs == NULL) {
1319 ret = -ENOMEM;
1320 goto error_free_scan_mask;
1321 }
1322 if (buffer->scan_el_attrs)
1323 memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
1324 sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
1325 attrn = attrcount_orig;
1326
1327 list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
1328 buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
1329 indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
1330
1331 return 0;
1332
1333 error_free_scan_mask:
1334 bitmap_free(buffer->scan_mask);
1335 error_cleanup_dynamic:
1336 iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
1337 kfree(indio_dev->buffer->buffer_group.attrs);
1338
1339 return ret;
1340 }
1341
1342 void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
1343 {
1344 if (!indio_dev->buffer)
1345 return;
1346
1347 bitmap_free(indio_dev->buffer->scan_mask);
1348 kfree(indio_dev->buffer->buffer_group.attrs);
1349 kfree(indio_dev->buffer->scan_el_group.attrs);
1350 iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
1351 }
1352
1353 /**
1354 * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1355 * @indio_dev: the iio device
1356 * @mask: scan mask to be checked
1357 *
1358 * Return true if exactly one bit is set in the scan mask, false otherwise. It
1359 * can be used for devices where only one channel can be active for sampling at
1360 * a time.
1361 */
1362 bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1363 const unsigned long *mask)
1364 {
1365 return bitmap_weight(mask, indio_dev->masklength) == 1;
1366 }
1367 EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1368
1369 static const void *iio_demux(struct iio_buffer *buffer,
1370 const void *datain)
1371 {
1372 struct iio_demux_table *t;
1373
1374 if (list_empty(&buffer->demux_list))
1375 return datain;
1376 list_for_each_entry(t, &buffer->demux_list, l)
1377 memcpy(buffer->demux_bounce + t->to,
1378 datain + t->from, t->length);
1379
1380 return buffer->demux_bounce;
1381 }
1382
1383 static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1384 {
1385 const void *dataout = iio_demux(buffer, data);
1386 int ret;
1387
1388 ret = buffer->access->store_to(buffer, dataout);
1389 if (ret)
1390 return ret;
1391
1392 /*
1393 * We can't just test for watermark to decide if we wake the poll queue
1394 * because read may request less samples than the watermark.
1395 */
1396 wake_up_interruptible_poll(&buffer->pollq, EPOLLIN | EPOLLRDNORM);
1397 return 0;
1398 }
1399
1400 /**
1401 * iio_push_to_buffers() - push to a registered buffer.
1402 * @indio_dev: iio_dev structure for device.
1403 * @data: Full scan.
1404 */
1405 int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1406 {
1407 int ret;
1408 struct iio_buffer *buf;
1409
1410 list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
1411 ret = iio_push_to_buffer(buf, data);
1412 if (ret < 0)
1413 return ret;
1414 }
1415
1416 return 0;
1417 }
1418 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1419
1420 /**
1421 * iio_buffer_release() - Free a buffer's resources
1422 * @ref: Pointer to the kref embedded in the iio_buffer struct
1423 *
1424 * This function is called when the last reference to the buffer has been
1425 * dropped. It will typically free all resources allocated by the buffer. Do not
1426 * call this function manually, always use iio_buffer_put() when done using a
1427 * buffer.
1428 */
1429 static void iio_buffer_release(struct kref *ref)
1430 {
1431 struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1432
1433 buffer->access->release(buffer);
1434 }
1435
1436 /**
1437 * iio_buffer_get() - Grab a reference to the buffer
1438 * @buffer: The buffer to grab a reference for, may be NULL
1439 *
1440 * Returns the pointer to the buffer that was passed into the function.
1441 */
1442 struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1443 {
1444 if (buffer)
1445 kref_get(&buffer->ref);
1446
1447 return buffer;
1448 }
1449 EXPORT_SYMBOL_GPL(iio_buffer_get);
1450
1451 /**
1452 * iio_buffer_put() - Release the reference to the buffer
1453 * @buffer: The buffer to release the reference for, may be NULL
1454 */
1455 void iio_buffer_put(struct iio_buffer *buffer)
1456 {
1457 if (buffer)
1458 kref_put(&buffer->ref, iio_buffer_release);
1459 }
1460 EXPORT_SYMBOL_GPL(iio_buffer_put);
1461
1462 /**
1463 * iio_device_attach_buffer - Attach a buffer to a IIO device
1464 * @indio_dev: The device the buffer should be attached to
1465 * @buffer: The buffer to attach to the device
1466 *
1467 * This function attaches a buffer to a IIO device. The buffer stays attached to
1468 * the device until the device is freed. The function should only be called at
1469 * most once per device.
1470 */
1471 void iio_device_attach_buffer(struct iio_dev *indio_dev,
1472 struct iio_buffer *buffer)
1473 {
1474 indio_dev->buffer = iio_buffer_get(buffer);
1475 }
1476 EXPORT_SYMBOL_GPL(iio_device_attach_buffer);
Linux with added FPC-III support