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/anon_inodes.h>
13	#include <linux/kernel.h>
14	#include <linux/export.h>
15	#include <linux/device.h>
16	#include <linux/file.h>
17	#include <linux/fs.h>
18	#include <linux/cdev.h>
19	#include <linux/slab.h>
20	#include <linux/poll.h>
21	#include <linux/sched/signal.h>
22
23	#include <linux/iio/iio.h>
24	#include <linux/iio/iio-opaque.h>
25	#include "iio_core.h"
26	#include "iio_core_trigger.h"
27	#include <linux/iio/sysfs.h>
28	#include <linux/iio/buffer.h>
29	#include <linux/iio/buffer_impl.h>
30
31	static const char * const iio_endian_prefix[] = {
32	[IIO_BE] = "be",
33	[IIO_LE] = "le",
34	};
35
36	static bool iio_buffer_is_active(struct iio_buffer *buf)
37	{
38	return !list_empty(head: &buf->buffer_list);
39	}
40
41	static size_t iio_buffer_data_available(struct iio_buffer *buf)
42	{
43	return buf->access->data_available(buf);
44	}
45
46	static 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
55	static 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	required: to_flush - avail);
78	return true;
79	}
80
81	if (to_flush)
82	flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
83	required: 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() - 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	**/
106	static ssize_t iio_buffer_read(struct file *filp, char __user *buf,
107	size_t n, loff_t *f_ps)
108	{
109	struct iio_dev_buffer_pair *ib = filp->private_data;
110	struct iio_buffer *rb = ib->buffer;
111	struct iio_dev *indio_dev = ib->indio_dev;
112	DEFINE_WAIT_FUNC(wait, woken_wake_function);
113	size_t datum_size;
114	size_t to_wait;
115	int ret = 0;
116
117	if (!indio_dev->info)
118	return -ENODEV;
119
120	if (!rb || !rb->access->read)
121	return -EINVAL;
122
123	if (rb->direction != IIO_BUFFER_DIRECTION_IN)
124	return -EPERM;
125
126	datum_size = rb->bytes_per_datum;
127
128	/*
129	* If datum_size is 0 there will never be anything to read from the
130	* buffer, so signal end of file now.
131	*/
132	if (!datum_size)
133	return 0;
134
135	if (filp->f_flags & O_NONBLOCK)
136	to_wait = 0;
137	else
138	to_wait = min_t(size_t, n / datum_size, rb->watermark);
139
140	add_wait_queue(wq_head: &rb->pollq, wq_entry: &wait);
141	do {
142	if (!indio_dev->info) {
143	ret = -ENODEV;
144	break;
145	}
146
147	if (!iio_buffer_ready(indio_dev, buf: rb, to_wait, to_flush: n / datum_size)) {
148	if (signal_pending(current)) {
149	ret = -ERESTARTSYS;
150	break;
151	}
152
153	wait_woken(wq_entry: &wait, TASK_INTERRUPTIBLE,
154	MAX_SCHEDULE_TIMEOUT);
155	continue;
156	}
157
158	ret = rb->access->read(rb, n, buf);
159	if (ret == 0 && (filp->f_flags & O_NONBLOCK))
160	ret = -EAGAIN;
161	} while (ret == 0);
162	remove_wait_queue(wq_head: &rb->pollq, wq_entry: &wait);
163
164	return ret;
165	}
166
167	static size_t iio_buffer_space_available(struct iio_buffer *buf)
168	{
169	if (buf->access->space_available)
170	return buf->access->space_available(buf);
171
172	return SIZE_MAX;
173	}
174
175	static ssize_t iio_buffer_write(struct file *filp, const char __user *buf,
176	size_t n, loff_t *f_ps)
177	{
178	struct iio_dev_buffer_pair *ib = filp->private_data;
179	struct iio_buffer *rb = ib->buffer;
180	struct iio_dev *indio_dev = ib->indio_dev;
181	DEFINE_WAIT_FUNC(wait, woken_wake_function);
182	int ret = 0;
183	size_t written;
184
185	if (!indio_dev->info)
186	return -ENODEV;
187
188	if (!rb || !rb->access->write)
189	return -EINVAL;
190
191	if (rb->direction != IIO_BUFFER_DIRECTION_OUT)
192	return -EPERM;
193
194	written = 0;
195	add_wait_queue(wq_head: &rb->pollq, wq_entry: &wait);
196	do {
197	if (!indio_dev->info)
198	return -ENODEV;
199
200	if (!iio_buffer_space_available(buf: rb)) {
201	if (signal_pending(current)) {
202	ret = -ERESTARTSYS;
203	break;
204	}
205
206	if (filp->f_flags & O_NONBLOCK) {
207	if (!written)
208	ret = -EAGAIN;
209	break;
210	}
211
212	wait_woken(wq_entry: &wait, TASK_INTERRUPTIBLE,
213	MAX_SCHEDULE_TIMEOUT);
214	continue;
215	}
216
217	ret = rb->access->write(rb, n - written, buf + written);
218	if (ret < 0)
219	break;
220
221	written += ret;
222
223	} while (written != n);
224	remove_wait_queue(wq_head: &rb->pollq, wq_entry: &wait);
225
226	return ret < 0 ? ret : written;
227	}
228
229	/**
230	* iio_buffer_poll() - poll the buffer to find out if it has data
231	* @filp: File structure pointer for device access
232	* @wait: Poll table structure pointer for which the driver adds
233	* a wait queue
234	*
235	* Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
236	* or 0 for other cases
237	*/
238	static __poll_t iio_buffer_poll(struct file *filp,
239	struct poll_table_struct *wait)
240	{
241	struct iio_dev_buffer_pair *ib = filp->private_data;
242	struct iio_buffer *rb = ib->buffer;
243	struct iio_dev *indio_dev = ib->indio_dev;
244
245	if (!indio_dev->info || !rb)
246	return 0;
247
248	poll_wait(filp, wait_address: &rb->pollq, p: wait);
249
250	switch (rb->direction) {
251	case IIO_BUFFER_DIRECTION_IN:
252	if (iio_buffer_ready(indio_dev, buf: rb, to_wait: rb->watermark, to_flush: 0))
253	return EPOLLIN | EPOLLRDNORM;
254	break;
255	case IIO_BUFFER_DIRECTION_OUT:
256	if (iio_buffer_space_available(buf: rb))
257	return EPOLLOUT | EPOLLWRNORM;
258	break;
259	}
260
261	return 0;
262	}
263
264	ssize_t iio_buffer_read_wrapper(struct file *filp, char __user *buf,
265	size_t n, loff_t *f_ps)
266	{
267	struct iio_dev_buffer_pair *ib = filp->private_data;
268	struct iio_buffer *rb = ib->buffer;
269
270	/* check if buffer was opened through new API */
271	if (test_bit(IIO_BUSY_BIT_POS, &rb->flags))
272	return -EBUSY;
273
274	return iio_buffer_read(filp, buf, n, f_ps);
275	}
276
277	ssize_t iio_buffer_write_wrapper(struct file *filp, const char __user *buf,
278	size_t n, loff_t *f_ps)
279	{
280	struct iio_dev_buffer_pair *ib = filp->private_data;
281	struct iio_buffer *rb = ib->buffer;
282
283	/* check if buffer was opened through new API */
284	if (test_bit(IIO_BUSY_BIT_POS, &rb->flags))
285	return -EBUSY;
286
287	return iio_buffer_write(filp, buf, n, f_ps);
288	}
289
290	__poll_t iio_buffer_poll_wrapper(struct file *filp,
291	struct poll_table_struct *wait)
292	{
293	struct iio_dev_buffer_pair *ib = filp->private_data;
294	struct iio_buffer *rb = ib->buffer;
295
296	/* check if buffer was opened through new API */
297	if (test_bit(IIO_BUSY_BIT_POS, &rb->flags))
298	return 0;
299
300	return iio_buffer_poll(filp, wait);
301	}
302
303	/**
304	* iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
305	* @indio_dev: The IIO device
306	*
307	* Wakes up the event waitqueue used for poll(). Should usually
308	* be called when the device is unregistered.
309	*/
310	void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
311	{
312	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
313	struct iio_buffer *buffer;
314	unsigned int i;
315
316	for (i = 0; i < iio_dev_opaque->attached_buffers_cnt; i++) {
317	buffer = iio_dev_opaque->attached_buffers[i];
318	wake_up(&buffer->pollq);
319	}
320	}
321
322	int iio_pop_from_buffer(struct iio_buffer *buffer, void *data)
323	{
324	if (!buffer || !buffer->access || !buffer->access->remove_from)
325	return -EINVAL;
326
327	return buffer->access->remove_from(buffer, data);
328	}
329	EXPORT_SYMBOL_GPL(iio_pop_from_buffer);
330
331	void iio_buffer_init(struct iio_buffer *buffer)
332	{
333	INIT_LIST_HEAD(list: &buffer->demux_list);
334	INIT_LIST_HEAD(list: &buffer->buffer_list);
335	init_waitqueue_head(&buffer->pollq);
336	kref_init(kref: &buffer->ref);
337	if (!buffer->watermark)
338	buffer->watermark = 1;
339	}
340	EXPORT_SYMBOL(iio_buffer_init);
341
342	void iio_device_detach_buffers(struct iio_dev *indio_dev)
343	{
344	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
345	struct iio_buffer *buffer;
346	unsigned int i;
347
348	for (i = 0; i < iio_dev_opaque->attached_buffers_cnt; i++) {
349	buffer = iio_dev_opaque->attached_buffers[i];
350	iio_buffer_put(buffer);
351	}
352
353	kfree(objp: iio_dev_opaque->attached_buffers);
354	}
355
356	static ssize_t iio_show_scan_index(struct device *dev,
357	struct device_attribute *attr,
358	char *buf)
359	{
360	return sysfs_emit(buf, fmt: "%u\n", to_iio_dev_attr(attr)->c->scan_index);
361	}
362
363	static ssize_t iio_show_fixed_type(struct device *dev,
364	struct device_attribute *attr,
365	char *buf)
366	{
367	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
368	u8 type = this_attr->c->scan_type.endianness;
369
370	if (type == IIO_CPU) {
371	#ifdef __LITTLE_ENDIAN
372	type = IIO_LE;
373	#else
374	type = IIO_BE;
375	#endif
376	}
377	if (this_attr->c->scan_type.repeat > 1)
378	return sysfs_emit(buf, fmt: "%s:%c%d/%dX%d>>%u\n",
379	iio_endian_prefix[type],
380	this_attr->c->scan_type.sign,
381	this_attr->c->scan_type.realbits,
382	this_attr->c->scan_type.storagebits,
383	this_attr->c->scan_type.repeat,
384	this_attr->c->scan_type.shift);
385	else
386	return sysfs_emit(buf, fmt: "%s:%c%d/%d>>%u\n",
387	iio_endian_prefix[type],
388	this_attr->c->scan_type.sign,
389	this_attr->c->scan_type.realbits,
390	this_attr->c->scan_type.storagebits,
391	this_attr->c->scan_type.shift);
392	}
393
394	static ssize_t iio_scan_el_show(struct device *dev,
395	struct device_attribute *attr,
396	char *buf)
397	{
398	int ret;
399	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
400
401	/* Ensure ret is 0 or 1. */
402	ret = !!test_bit(to_iio_dev_attr(attr)->address,
403	buffer->scan_mask);
404
405	return sysfs_emit(buf, fmt: "%d\n", ret);
406	}
407
408	/* Note NULL used as error indicator as it doesn't make sense. */
409	static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
410	unsigned int masklength,
411	const unsigned long *mask,
412	bool strict)
413	{
414	if (bitmap_empty(src: mask, nbits: masklength))
415	return NULL;
416	/*
417	* The condition here do not handle multi-long masks correctly.
418	* It only checks the first long to be zero, and will use such mask
419	* as a terminator even if there was bits set after the first long.
420	*
421	* Correct check would require using:
422	* while (!bitmap_empty(av_masks, masklength))
423	* instead. This is potentially hazardous because the
424	* avaliable_scan_masks is a zero terminated array of longs - and
425	* using the proper bitmap_empty() check for multi-long wide masks
426	* would require the array to be terminated with multiple zero longs -
427	* which is not such an usual pattern.
428	*
429	* As writing of this no multi-long wide masks were found in-tree, so
430	* the simple while (*av_masks) check is working.
431	*/
432	while (*av_masks) {
433	if (strict) {
434	if (bitmap_equal(src1: mask, src2: av_masks, nbits: masklength))
435	return av_masks;
436	} else {
437	if (bitmap_subset(src1: mask, src2: av_masks, nbits: masklength))
438	return av_masks;
439	}
440	av_masks += BITS_TO_LONGS(masklength);
441	}
442	return NULL;
443	}
444
445	static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
446	const unsigned long *mask)
447	{
448	if (!indio_dev->setup_ops->validate_scan_mask)
449	return true;
450
451	return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
452	}
453
454	/**
455	* iio_scan_mask_set() - set particular bit in the scan mask
456	* @indio_dev: the iio device
457	* @buffer: the buffer whose scan mask we are interested in
458	* @bit: the bit to be set.
459	*
460	* Note that at this point we have no way of knowing what other
461	* buffers might request, hence this code only verifies that the
462	* individual buffers request is plausible.
463	*/
464	static int iio_scan_mask_set(struct iio_dev *indio_dev,
465	struct iio_buffer *buffer, int bit)
466	{
467	const unsigned long *mask;
468	unsigned long *trialmask;
469
470	if (!indio_dev->masklength) {
471	WARN(1, "Trying to set scanmask prior to registering buffer\n");
472	return -EINVAL;
473	}
474
475	trialmask = bitmap_alloc(nbits: indio_dev->masklength, GFP_KERNEL);
476	if (!trialmask)
477	return -ENOMEM;
478	bitmap_copy(dst: trialmask, src: buffer->scan_mask, nbits: indio_dev->masklength);
479	set_bit(nr: bit, addr: trialmask);
480
481	if (!iio_validate_scan_mask(indio_dev, mask: trialmask))
482	goto err_invalid_mask;
483
484	if (indio_dev->available_scan_masks) {
485	mask = iio_scan_mask_match(av_masks: indio_dev->available_scan_masks,
486	masklength: indio_dev->masklength,
487	mask: trialmask, strict: false);
488	if (!mask)
489	goto err_invalid_mask;
490	}
491	bitmap_copy(dst: buffer->scan_mask, src: trialmask, nbits: indio_dev->masklength);
492
493	bitmap_free(bitmap: trialmask);
494
495	return 0;
496
497	err_invalid_mask:
498	bitmap_free(bitmap: trialmask);
499	return -EINVAL;
500	}
501
502	static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
503	{
504	clear_bit(nr: bit, addr: buffer->scan_mask);
505	return 0;
506	}
507
508	static int iio_scan_mask_query(struct iio_dev *indio_dev,
509	struct iio_buffer *buffer, int bit)
510	{
511	if (bit > indio_dev->masklength)
512	return -EINVAL;
513
514	if (!buffer->scan_mask)
515	return 0;
516
517	/* Ensure return value is 0 or 1. */
518	return !!test_bit(bit, buffer->scan_mask);
519	};
520
521	static ssize_t iio_scan_el_store(struct device *dev,
522	struct device_attribute *attr,
523	const char *buf,
524	size_t len)
525	{
526	int ret;
527	bool state;
528	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
529	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
530	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
531	struct iio_buffer *buffer = this_attr->buffer;
532
533	ret = kstrtobool(s: buf, res: &state);
534	if (ret < 0)
535	return ret;
536	mutex_lock(&iio_dev_opaque->mlock);
537	if (iio_buffer_is_active(buf: buffer)) {
538	ret = -EBUSY;
539	goto error_ret;
540	}
541	ret = iio_scan_mask_query(indio_dev, buffer, bit: this_attr->address);
542	if (ret < 0)
543	goto error_ret;
544	if (!state && ret) {
545	ret = iio_scan_mask_clear(buffer, bit: this_attr->address);
546	if (ret)
547	goto error_ret;
548	} else if (state && !ret) {
549	ret = iio_scan_mask_set(indio_dev, buffer, bit: this_attr->address);
550	if (ret)
551	goto error_ret;
552	}
553
554	error_ret:
555	mutex_unlock(lock: &iio_dev_opaque->mlock);
556
557	return ret < 0 ? ret : len;
558	}
559
560	static ssize_t iio_scan_el_ts_show(struct device *dev,
561	struct device_attribute *attr,
562	char *buf)
563	{
564	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
565
566	return sysfs_emit(buf, fmt: "%d\n", buffer->scan_timestamp);
567	}
568
569	static ssize_t iio_scan_el_ts_store(struct device *dev,
570	struct device_attribute *attr,
571	const char *buf,
572	size_t len)
573	{
574	int ret;
575	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
576	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
577	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
578	bool state;
579
580	ret = kstrtobool(s: buf, res: &state);
581	if (ret < 0)
582	return ret;
583
584	mutex_lock(&iio_dev_opaque->mlock);
585	if (iio_buffer_is_active(buf: buffer)) {
586	ret = -EBUSY;
587	goto error_ret;
588	}
589	buffer->scan_timestamp = state;
590	error_ret:
591	mutex_unlock(lock: &iio_dev_opaque->mlock);
592
593	return ret ? ret : len;
594	}
595
596	static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
597	struct iio_buffer *buffer,
598	const struct iio_chan_spec *chan)
599	{
600	int ret, attrcount = 0;
601
602	ret = __iio_add_chan_devattr(postfix: "index",
603	chan,
604	func: &iio_show_scan_index,
605	NULL,
606	mask: 0,
607	shared_by: IIO_SEPARATE,
608	dev: &indio_dev->dev,
609	buffer,
610	attr_list: &buffer->buffer_attr_list);
611	if (ret)
612	return ret;
613	attrcount++;
614	ret = __iio_add_chan_devattr(postfix: "type",
615	chan,
616	func: &iio_show_fixed_type,
617	NULL,
618	mask: 0,
619	shared_by: IIO_SEPARATE,
620	dev: &indio_dev->dev,
621	buffer,
622	attr_list: &buffer->buffer_attr_list);
623	if (ret)
624	return ret;
625	attrcount++;
626	if (chan->type != IIO_TIMESTAMP)
627	ret = __iio_add_chan_devattr(postfix: "en",
628	chan,
629	func: &iio_scan_el_show,
630	writefunc: &iio_scan_el_store,
631	mask: chan->scan_index,
632	shared_by: IIO_SEPARATE,
633	dev: &indio_dev->dev,
634	buffer,
635	attr_list: &buffer->buffer_attr_list);
636	else
637	ret = __iio_add_chan_devattr(postfix: "en",
638	chan,
639	func: &iio_scan_el_ts_show,
640	writefunc: &iio_scan_el_ts_store,
641	mask: chan->scan_index,
642	shared_by: IIO_SEPARATE,
643	dev: &indio_dev->dev,
644	buffer,
645	attr_list: &buffer->buffer_attr_list);
646	if (ret)
647	return ret;
648	attrcount++;
649	ret = attrcount;
650	return ret;
651	}
652
653	static ssize_t length_show(struct device *dev, struct device_attribute *attr,
654	char *buf)
655	{
656	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
657
658	return sysfs_emit(buf, fmt: "%d\n", buffer->length);
659	}
660
661	static ssize_t length_store(struct device *dev, struct device_attribute *attr,
662	const char *buf, size_t len)
663	{
664	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
665	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
666	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
667	unsigned int val;
668	int ret;
669
670	ret = kstrtouint(s: buf, base: 10, res: &val);
671	if (ret)
672	return ret;
673
674	if (val == buffer->length)
675	return len;
676
677	mutex_lock(&iio_dev_opaque->mlock);
678	if (iio_buffer_is_active(buf: buffer)) {
679	ret = -EBUSY;
680	} else {
681	buffer->access->set_length(buffer, val);
682	ret = 0;
683	}
684	if (ret)
685	goto out;
686	if (buffer->length && buffer->length < buffer->watermark)
687	buffer->watermark = buffer->length;
688	out:
689	mutex_unlock(lock: &iio_dev_opaque->mlock);
690
691	return ret ? ret : len;
692	}
693
694	static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
695	char *buf)
696	{
697	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
698
699	return sysfs_emit(buf, fmt: "%d\n", iio_buffer_is_active(buf: buffer));
700	}
701
702	static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
703	unsigned int scan_index)
704	{
705	const struct iio_chan_spec *ch;
706	unsigned int bytes;
707
708	ch = iio_find_channel_from_si(indio_dev, si: scan_index);
709	bytes = ch->scan_type.storagebits / 8;
710	if (ch->scan_type.repeat > 1)
711	bytes *= ch->scan_type.repeat;
712	return bytes;
713	}
714
715	static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
716	{
717	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
718
719	return iio_storage_bytes_for_si(indio_dev,
720	scan_index: iio_dev_opaque->scan_index_timestamp);
721	}
722
723	static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
724	const unsigned long *mask, bool timestamp)
725	{
726	unsigned int bytes = 0;
727	int length, i, largest = 0;
728
729	/* How much space will the demuxed element take? */
730	for_each_set_bit(i, mask,
731	indio_dev->masklength) {
732	length = iio_storage_bytes_for_si(indio_dev, scan_index: i);
733	bytes = ALIGN(bytes, length);
734	bytes += length;
735	largest = max(largest, length);
736	}
737
738	if (timestamp) {
739	length = iio_storage_bytes_for_timestamp(indio_dev);
740	bytes = ALIGN(bytes, length);
741	bytes += length;
742	largest = max(largest, length);
743	}
744
745	bytes = ALIGN(bytes, largest);
746	return bytes;
747	}
748
749	static void iio_buffer_activate(struct iio_dev *indio_dev,
750	struct iio_buffer *buffer)
751	{
752	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
753
754	iio_buffer_get(buffer);
755	list_add(new: &buffer->buffer_list, head: &iio_dev_opaque->buffer_list);
756	}
757
758	static void iio_buffer_deactivate(struct iio_buffer *buffer)
759	{
760	list_del_init(entry: &buffer->buffer_list);
761	wake_up_interruptible(&buffer->pollq);
762	iio_buffer_put(buffer);
763	}
764
765	static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
766	{
767	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
768	struct iio_buffer *buffer, *_buffer;
769
770	list_for_each_entry_safe(buffer, _buffer,
771	&iio_dev_opaque->buffer_list, buffer_list)
772	iio_buffer_deactivate(buffer);
773	}
774
775	static int iio_buffer_enable(struct iio_buffer *buffer,
776	struct iio_dev *indio_dev)
777	{
778	if (!buffer->access->enable)
779	return 0;
780	return buffer->access->enable(buffer, indio_dev);
781	}
782
783	static int iio_buffer_disable(struct iio_buffer *buffer,
784	struct iio_dev *indio_dev)
785	{
786	if (!buffer->access->disable)
787	return 0;
788	return buffer->access->disable(buffer, indio_dev);
789	}
790
791	static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
792	struct iio_buffer *buffer)
793	{
794	unsigned int bytes;
795
796	if (!buffer->access->set_bytes_per_datum)
797	return;
798
799	bytes = iio_compute_scan_bytes(indio_dev, mask: buffer->scan_mask,
800	timestamp: buffer->scan_timestamp);
801
802	buffer->access->set_bytes_per_datum(buffer, bytes);
803	}
804
805	static int iio_buffer_request_update(struct iio_dev *indio_dev,
806	struct iio_buffer *buffer)
807	{
808	int ret;
809
810	iio_buffer_update_bytes_per_datum(indio_dev, buffer);
811	if (buffer->access->request_update) {
812	ret = buffer->access->request_update(buffer);
813	if (ret) {
814	dev_dbg(&indio_dev->dev,
815	"Buffer not started: buffer parameter update failed (%d)\n",
816	ret);
817	return ret;
818	}
819	}
820
821	return 0;
822	}
823
824	static void iio_free_scan_mask(struct iio_dev *indio_dev,
825	const unsigned long *mask)
826	{
827	/* If the mask is dynamically allocated free it, otherwise do nothing */
828	if (!indio_dev->available_scan_masks)
829	bitmap_free(bitmap: mask);
830	}
831
832	struct iio_device_config {
833	unsigned int mode;
834	unsigned int watermark;
835	const unsigned long *scan_mask;
836	unsigned int scan_bytes;
837	bool scan_timestamp;
838	};
839
840	static int iio_verify_update(struct iio_dev *indio_dev,
841	struct iio_buffer *insert_buffer,
842	struct iio_buffer *remove_buffer,
843	struct iio_device_config *config)
844	{
845	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
846	unsigned long *compound_mask;
847	const unsigned long *scan_mask;
848	bool strict_scanmask = false;
849	struct iio_buffer *buffer;
850	bool scan_timestamp;
851	unsigned int modes;
852
853	if (insert_buffer &&
854	bitmap_empty(src: insert_buffer->scan_mask, nbits: indio_dev->masklength)) {
855	dev_dbg(&indio_dev->dev,
856	"At least one scan element must be enabled first\n");
857	return -EINVAL;
858	}
859
860	memset(config, 0, sizeof(*config));
861	config->watermark = ~0;
862
863	/*
864	* If there is just one buffer and we are removing it there is nothing
865	* to verify.
866	*/
867	if (remove_buffer && !insert_buffer &&
868	list_is_singular(head: &iio_dev_opaque->buffer_list))
869	return 0;
870
871	modes = indio_dev->modes;
872
873	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list) {
874	if (buffer == remove_buffer)
875	continue;
876	modes &= buffer->access->modes;
877	config->watermark = min(config->watermark, buffer->watermark);
878	}
879
880	if (insert_buffer) {
881	modes &= insert_buffer->access->modes;
882	config->watermark = min(config->watermark,
883	insert_buffer->watermark);
884	}
885
886	/* Definitely possible for devices to support both of these. */
887	if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
888	config->mode = INDIO_BUFFER_TRIGGERED;
889	} else if (modes & INDIO_BUFFER_HARDWARE) {
890	/*
891	* Keep things simple for now and only allow a single buffer to
892	* be connected in hardware mode.
893	*/
894	if (insert_buffer && !list_empty(head: &iio_dev_opaque->buffer_list))
895	return -EINVAL;
896	config->mode = INDIO_BUFFER_HARDWARE;
897	strict_scanmask = true;
898	} else if (modes & INDIO_BUFFER_SOFTWARE) {
899	config->mode = INDIO_BUFFER_SOFTWARE;
900	} else {
901	/* Can only occur on first buffer */
902	if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
903	dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
904	return -EINVAL;
905	}
906
907	/* What scan mask do we actually have? */
908	compound_mask = bitmap_zalloc(nbits: indio_dev->masklength, GFP_KERNEL);
909	if (!compound_mask)
910	return -ENOMEM;
911
912	scan_timestamp = false;
913
914	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list) {
915	if (buffer == remove_buffer)
916	continue;
917	bitmap_or(dst: compound_mask, src1: compound_mask, src2: buffer->scan_mask,
918	nbits: indio_dev->masklength);
919	scan_timestamp |= buffer->scan_timestamp;
920	}
921
922	if (insert_buffer) {
923	bitmap_or(dst: compound_mask, src1: compound_mask,
924	src2: insert_buffer->scan_mask, nbits: indio_dev->masklength);
925	scan_timestamp |= insert_buffer->scan_timestamp;
926	}
927
928	if (indio_dev->available_scan_masks) {
929	scan_mask = iio_scan_mask_match(av_masks: indio_dev->available_scan_masks,
930	masklength: indio_dev->masklength,
931	mask: compound_mask,
932	strict: strict_scanmask);
933	bitmap_free(bitmap: compound_mask);
934	if (!scan_mask)
935	return -EINVAL;
936	} else {
937	scan_mask = compound_mask;
938	}
939
940	config->scan_bytes = iio_compute_scan_bytes(indio_dev,
941	mask: scan_mask, timestamp: scan_timestamp);
942	config->scan_mask = scan_mask;
943	config->scan_timestamp = scan_timestamp;
944
945	return 0;
946	}
947
948	/**
949	* struct iio_demux_table - table describing demux memcpy ops
950	* @from: index to copy from
951	* @to: index to copy to
952	* @length: how many bytes to copy
953	* @l: list head used for management
954	*/
955	struct iio_demux_table {
956	unsigned int from;
957	unsigned int to;
958	unsigned int length;
959	struct list_head l;
960	};
961
962	static void iio_buffer_demux_free(struct iio_buffer *buffer)
963	{
964	struct iio_demux_table *p, *q;
965
966	list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
967	list_del(entry: &p->l);
968	kfree(objp: p);
969	}
970	}
971
972	static int iio_buffer_add_demux(struct iio_buffer *buffer,
973	struct iio_demux_table **p, unsigned int in_loc,
974	unsigned int out_loc,
975	unsigned int length)
976	{
977	if (*p && (*p)->from + (*p)->length == in_loc &&
978	(*p)->to + (*p)->length == out_loc) {
979	(*p)->length += length;
980	} else {
981	*p = kmalloc(size: sizeof(**p), GFP_KERNEL);
982	if (!(*p))
983	return -ENOMEM;
984	(*p)->from = in_loc;
985	(*p)->to = out_loc;
986	(*p)->length = length;
987	list_add_tail(new: &(*p)->l, head: &buffer->demux_list);
988	}
989
990	return 0;
991	}
992
993	static int iio_buffer_update_demux(struct iio_dev *indio_dev,
994	struct iio_buffer *buffer)
995	{
996	int ret, in_ind = -1, out_ind, length;
997	unsigned int in_loc = 0, out_loc = 0;
998	struct iio_demux_table *p = NULL;
999
1000	/* Clear out any old demux */
1001	iio_buffer_demux_free(buffer);
1002	kfree(objp: buffer->demux_bounce);
1003	buffer->demux_bounce = NULL;
1004
1005	/* First work out which scan mode we will actually have */
1006	if (bitmap_equal(src1: indio_dev->active_scan_mask,
1007	src2: buffer->scan_mask,
1008	nbits: indio_dev->masklength))
1009	return 0;
1010
1011	/* Now we have the two masks, work from least sig and build up sizes */
1012	for_each_set_bit(out_ind,
1013	buffer->scan_mask,
1014	indio_dev->masklength) {
1015	in_ind = find_next_bit(addr: indio_dev->active_scan_mask,
1016	size: indio_dev->masklength,
1017	offset: in_ind + 1);
1018	while (in_ind != out_ind) {
1019	length = iio_storage_bytes_for_si(indio_dev, scan_index: in_ind);
1020	/* Make sure we are aligned */
1021	in_loc = roundup(in_loc, length) + length;
1022	in_ind = find_next_bit(addr: indio_dev->active_scan_mask,
1023	size: indio_dev->masklength,
1024	offset: in_ind + 1);
1025	}
1026	length = iio_storage_bytes_for_si(indio_dev, scan_index: in_ind);
1027	out_loc = roundup(out_loc, length);
1028	in_loc = roundup(in_loc, length);
1029	ret = iio_buffer_add_demux(buffer, p: &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	/* Relies on scan_timestamp being last */
1036	if (buffer->scan_timestamp) {
1037	length = iio_storage_bytes_for_timestamp(indio_dev);
1038	out_loc = roundup(out_loc, length);
1039	in_loc = roundup(in_loc, length);
1040	ret = iio_buffer_add_demux(buffer, p: &p, in_loc, out_loc, length);
1041	if (ret)
1042	goto error_clear_mux_table;
1043	out_loc += length;
1044	}
1045	buffer->demux_bounce = kzalloc(size: out_loc, GFP_KERNEL);
1046	if (!buffer->demux_bounce) {
1047	ret = -ENOMEM;
1048	goto error_clear_mux_table;
1049	}
1050	return 0;
1051
1052	error_clear_mux_table:
1053	iio_buffer_demux_free(buffer);
1054
1055	return ret;
1056	}
1057
1058	static int iio_update_demux(struct iio_dev *indio_dev)
1059	{
1060	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1061	struct iio_buffer *buffer;
1062	int ret;
1063
1064	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list) {
1065	ret = iio_buffer_update_demux(indio_dev, buffer);
1066	if (ret < 0)
1067	goto error_clear_mux_table;
1068	}
1069	return 0;
1070
1071	error_clear_mux_table:
1072	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list)
1073	iio_buffer_demux_free(buffer);
1074
1075	return ret;
1076	}
1077
1078	static int iio_enable_buffers(struct iio_dev *indio_dev,
1079	struct iio_device_config *config)
1080	{
1081	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1082	struct iio_buffer *buffer, *tmp = NULL;
1083	int ret;
1084
1085	indio_dev->active_scan_mask = config->scan_mask;
1086	indio_dev->scan_timestamp = config->scan_timestamp;
1087	indio_dev->scan_bytes = config->scan_bytes;
1088	iio_dev_opaque->currentmode = config->mode;
1089
1090	iio_update_demux(indio_dev);
1091
1092	/* Wind up again */
1093	if (indio_dev->setup_ops->preenable) {
1094	ret = indio_dev->setup_ops->preenable(indio_dev);
1095	if (ret) {
1096	dev_dbg(&indio_dev->dev,
1097	"Buffer not started: buffer preenable failed (%d)\n", ret);
1098	goto err_undo_config;
1099	}
1100	}
1101
1102	if (indio_dev->info->update_scan_mode) {
1103	ret = indio_dev->info
1104	->update_scan_mode(indio_dev,
1105	indio_dev->active_scan_mask);
1106	if (ret < 0) {
1107	dev_dbg(&indio_dev->dev,
1108	"Buffer not started: update scan mode failed (%d)\n",
1109	ret);
1110	goto err_run_postdisable;
1111	}
1112	}
1113
1114	if (indio_dev->info->hwfifo_set_watermark)
1115	indio_dev->info->hwfifo_set_watermark(indio_dev,
1116	config->watermark);
1117
1118	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list) {
1119	ret = iio_buffer_enable(buffer, indio_dev);
1120	if (ret) {
1121	tmp = buffer;
1122	goto err_disable_buffers;
1123	}
1124	}
1125
1126	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
1127	ret = iio_trigger_attach_poll_func(trig: indio_dev->trig,
1128	pf: indio_dev->pollfunc);
1129	if (ret)
1130	goto err_disable_buffers;
1131	}
1132
1133	if (indio_dev->setup_ops->postenable) {
1134	ret = indio_dev->setup_ops->postenable(indio_dev);
1135	if (ret) {
1136	dev_dbg(&indio_dev->dev,
1137	"Buffer not started: postenable failed (%d)\n", ret);
1138	goto err_detach_pollfunc;
1139	}
1140	}
1141
1142	return 0;
1143
1144	err_detach_pollfunc:
1145	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
1146	iio_trigger_detach_poll_func(trig: indio_dev->trig,
1147	pf: indio_dev->pollfunc);
1148	}
1149	err_disable_buffers:
1150	buffer = list_prepare_entry(tmp, &iio_dev_opaque->buffer_list, buffer_list);
1151	list_for_each_entry_continue_reverse(buffer, &iio_dev_opaque->buffer_list,
1152	buffer_list)
1153	iio_buffer_disable(buffer, indio_dev);
1154	err_run_postdisable:
1155	if (indio_dev->setup_ops->postdisable)
1156	indio_dev->setup_ops->postdisable(indio_dev);
1157	err_undo_config:
1158	iio_dev_opaque->currentmode = INDIO_DIRECT_MODE;
1159	indio_dev->active_scan_mask = NULL;
1160
1161	return ret;
1162	}
1163
1164	static int iio_disable_buffers(struct iio_dev *indio_dev)
1165	{
1166	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1167	struct iio_buffer *buffer;
1168	int ret = 0;
1169	int ret2;
1170
1171	/* Wind down existing buffers - iff there are any */
1172	if (list_empty(head: &iio_dev_opaque->buffer_list))
1173	return 0;
1174
1175	/*
1176	* If things go wrong at some step in disable we still need to continue
1177	* to perform the other steps, otherwise we leave the device in a
1178	* inconsistent state. We return the error code for the first error we
1179	* encountered.
1180	*/
1181
1182	if (indio_dev->setup_ops->predisable) {
1183	ret2 = indio_dev->setup_ops->predisable(indio_dev);
1184	if (ret2 && !ret)
1185	ret = ret2;
1186	}
1187
1188	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
1189	iio_trigger_detach_poll_func(trig: indio_dev->trig,
1190	pf: indio_dev->pollfunc);
1191	}
1192
1193	list_for_each_entry(buffer, &iio_dev_opaque->buffer_list, buffer_list) {
1194	ret2 = iio_buffer_disable(buffer, indio_dev);
1195	if (ret2 && !ret)
1196	ret = ret2;
1197	}
1198
1199	if (indio_dev->setup_ops->postdisable) {
1200	ret2 = indio_dev->setup_ops->postdisable(indio_dev);
1201	if (ret2 && !ret)
1202	ret = ret2;
1203	}
1204
1205	iio_free_scan_mask(indio_dev, mask: indio_dev->active_scan_mask);
1206	indio_dev->active_scan_mask = NULL;
1207	iio_dev_opaque->currentmode = INDIO_DIRECT_MODE;
1208
1209	return ret;
1210	}
1211
1212	static int __iio_update_buffers(struct iio_dev *indio_dev,
1213	struct iio_buffer *insert_buffer,
1214	struct iio_buffer *remove_buffer)
1215	{
1216	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1217	struct iio_device_config new_config;
1218	int ret;
1219
1220	ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
1221	config: &new_config);
1222	if (ret)
1223	return ret;
1224
1225	if (insert_buffer) {
1226	ret = iio_buffer_request_update(indio_dev, buffer: insert_buffer);
1227	if (ret)
1228	goto err_free_config;
1229	}
1230
1231	ret = iio_disable_buffers(indio_dev);
1232	if (ret)
1233	goto err_deactivate_all;
1234
1235	if (remove_buffer)
1236	iio_buffer_deactivate(buffer: remove_buffer);
1237	if (insert_buffer)
1238	iio_buffer_activate(indio_dev, buffer: insert_buffer);
1239
1240	/* If no buffers in list, we are done */
1241	if (list_empty(head: &iio_dev_opaque->buffer_list))
1242	return 0;
1243
1244	ret = iio_enable_buffers(indio_dev, config: &new_config);
1245	if (ret)
1246	goto err_deactivate_all;
1247
1248	return 0;
1249
1250	err_deactivate_all:
1251	/*
1252	* We've already verified that the config is valid earlier. If things go
1253	* wrong in either enable or disable the most likely reason is an IO
1254	* error from the device. In this case there is no good recovery
1255	* strategy. Just make sure to disable everything and leave the device
1256	* in a sane state. With a bit of luck the device might come back to
1257	* life again later and userspace can try again.
1258	*/
1259	iio_buffer_deactivate_all(indio_dev);
1260
1261	err_free_config:
1262	iio_free_scan_mask(indio_dev, mask: new_config.scan_mask);
1263	return ret;
1264	}
1265
1266	int iio_update_buffers(struct iio_dev *indio_dev,
1267	struct iio_buffer *insert_buffer,
1268	struct iio_buffer *remove_buffer)
1269	{
1270	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1271	int ret;
1272
1273	if (insert_buffer == remove_buffer)
1274	return 0;
1275
1276	if (insert_buffer &&
1277	insert_buffer->direction == IIO_BUFFER_DIRECTION_OUT)
1278	return -EINVAL;
1279
1280	mutex_lock(&iio_dev_opaque->info_exist_lock);
1281	mutex_lock(&iio_dev_opaque->mlock);
1282
1283	if (insert_buffer && iio_buffer_is_active(buf: insert_buffer))
1284	insert_buffer = NULL;
1285
1286	if (remove_buffer && !iio_buffer_is_active(buf: remove_buffer))
1287	remove_buffer = NULL;
1288
1289	if (!insert_buffer && !remove_buffer) {
1290	ret = 0;
1291	goto out_unlock;
1292	}
1293
1294	if (!indio_dev->info) {
1295	ret = -ENODEV;
1296	goto out_unlock;
1297	}
1298
1299	ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
1300
1301	out_unlock:
1302	mutex_unlock(lock: &iio_dev_opaque->mlock);
1303	mutex_unlock(lock: &iio_dev_opaque->info_exist_lock);
1304
1305	return ret;
1306	}
1307	EXPORT_SYMBOL_GPL(iio_update_buffers);
1308
1309	void iio_disable_all_buffers(struct iio_dev *indio_dev)
1310	{
1311	iio_disable_buffers(indio_dev);
1312	iio_buffer_deactivate_all(indio_dev);
1313	}
1314
1315	static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
1316	const char *buf, size_t len)
1317	{
1318	int ret;
1319	bool requested_state;
1320	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1321	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1322	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
1323	bool inlist;
1324
1325	ret = kstrtobool(s: buf, res: &requested_state);
1326	if (ret < 0)
1327	return ret;
1328
1329	mutex_lock(&iio_dev_opaque->mlock);
1330
1331	/* Find out if it is in the list */
1332	inlist = iio_buffer_is_active(buf: buffer);
1333	/* Already in desired state */
1334	if (inlist == requested_state)
1335	goto done;
1336
1337	if (requested_state)
1338	ret = __iio_update_buffers(indio_dev, insert_buffer: buffer, NULL);
1339	else
1340	ret = __iio_update_buffers(indio_dev, NULL, remove_buffer: buffer);
1341
1342	done:
1343	mutex_unlock(lock: &iio_dev_opaque->mlock);
1344	return (ret < 0) ? ret : len;
1345	}
1346
1347	static ssize_t watermark_show(struct device *dev, struct device_attribute *attr,
1348	char *buf)
1349	{
1350	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
1351
1352	return sysfs_emit(buf, fmt: "%u\n", buffer->watermark);
1353	}
1354
1355	static ssize_t watermark_store(struct device *dev,
1356	struct device_attribute *attr,
1357	const char *buf, size_t len)
1358	{
1359	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
1360	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1361	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
1362	unsigned int val;
1363	int ret;
1364
1365	ret = kstrtouint(s: buf, base: 10, res: &val);
1366	if (ret)
1367	return ret;
1368	if (!val)
1369	return -EINVAL;
1370
1371	mutex_lock(&iio_dev_opaque->mlock);
1372
1373	if (val > buffer->length) {
1374	ret = -EINVAL;
1375	goto out;
1376	}
1377
1378	if (iio_buffer_is_active(buf: buffer)) {
1379	ret = -EBUSY;
1380	goto out;
1381	}
1382
1383	buffer->watermark = val;
1384	out:
1385	mutex_unlock(lock: &iio_dev_opaque->mlock);
1386
1387	return ret ? ret : len;
1388	}
1389
1390	static ssize_t data_available_show(struct device *dev,
1391	struct device_attribute *attr, char *buf)
1392	{
1393	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
1394
1395	return sysfs_emit(buf, fmt: "%zu\n", iio_buffer_data_available(buf: buffer));
1396	}
1397
1398	static ssize_t direction_show(struct device *dev,
1399	struct device_attribute *attr,
1400	char *buf)
1401	{
1402	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
1403
1404	switch (buffer->direction) {
1405	case IIO_BUFFER_DIRECTION_IN:
1406	return sysfs_emit(buf, fmt: "in\n");
1407	case IIO_BUFFER_DIRECTION_OUT:
1408	return sysfs_emit(buf, fmt: "out\n");
1409	default:
1410	return -EINVAL;
1411	}
1412	}
1413
1414	static DEVICE_ATTR_RW(length);
1415	static struct device_attribute dev_attr_length_ro = __ATTR_RO(length);
1416	static DEVICE_ATTR_RW(enable);
1417	static DEVICE_ATTR_RW(watermark);
1418	static struct device_attribute dev_attr_watermark_ro = __ATTR_RO(watermark);
1419	static DEVICE_ATTR_RO(data_available);
1420	static DEVICE_ATTR_RO(direction);
1421
1422	/*
1423	* When adding new attributes here, put the at the end, at least until
1424	* the code that handles the length/length_ro & watermark/watermark_ro
1425	* assignments gets cleaned up. Otherwise these can create some weird
1426	* duplicate attributes errors under some setups.
1427	*/
1428	static struct attribute *iio_buffer_attrs[] = {
1429	&dev_attr_length.attr,
1430	&dev_attr_enable.attr,
1431	&dev_attr_watermark.attr,
1432	&dev_attr_data_available.attr,
1433	&dev_attr_direction.attr,
1434	};
1435
1436	#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
1437
1438	static struct attribute *iio_buffer_wrap_attr(struct iio_buffer *buffer,
1439	struct attribute *attr)
1440	{
1441	struct device_attribute *dattr = to_dev_attr(attr);
1442	struct iio_dev_attr *iio_attr;
1443
1444	iio_attr = kzalloc(size: sizeof(*iio_attr), GFP_KERNEL);
1445	if (!iio_attr)
1446	return NULL;
1447
1448	iio_attr->buffer = buffer;
1449	memcpy(&iio_attr->dev_attr, dattr, sizeof(iio_attr->dev_attr));
1450	iio_attr->dev_attr.attr.name = kstrdup_const(s: attr->name, GFP_KERNEL);
1451	if (!iio_attr->dev_attr.attr.name) {
1452	kfree(objp: iio_attr);
1453	return NULL;
1454	}
1455
1456	sysfs_attr_init(&iio_attr->dev_attr.attr);
1457
1458	list_add(new: &iio_attr->l, head: &buffer->buffer_attr_list);
1459
1460	return &iio_attr->dev_attr.attr;
1461	}
1462
1463	static int iio_buffer_register_legacy_sysfs_groups(struct iio_dev *indio_dev,
1464	struct attribute **buffer_attrs,
1465	int buffer_attrcount,
1466	int scan_el_attrcount)
1467	{
1468	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1469	struct attribute_group *group;
1470	struct attribute **attrs;
1471	int ret;
1472
1473	attrs = kcalloc(n: buffer_attrcount + 1, size: sizeof(*attrs), GFP_KERNEL);
1474	if (!attrs)
1475	return -ENOMEM;
1476
1477	memcpy(attrs, buffer_attrs, buffer_attrcount * sizeof(*attrs));
1478
1479	group = &iio_dev_opaque->legacy_buffer_group;
1480	group->attrs = attrs;
1481	group->name = "buffer";
1482
1483	ret = iio_device_register_sysfs_group(indio_dev, group);
1484	if (ret)
1485	goto error_free_buffer_attrs;
1486
1487	attrs = kcalloc(n: scan_el_attrcount + 1, size: sizeof(*attrs), GFP_KERNEL);
1488	if (!attrs) {
1489	ret = -ENOMEM;
1490	goto error_free_buffer_attrs;
1491	}
1492
1493	memcpy(attrs, &buffer_attrs[buffer_attrcount],
1494	scan_el_attrcount * sizeof(*attrs));
1495
1496	group = &iio_dev_opaque->legacy_scan_el_group;
1497	group->attrs = attrs;
1498	group->name = "scan_elements";
1499
1500	ret = iio_device_register_sysfs_group(indio_dev, group);
1501	if (ret)
1502	goto error_free_scan_el_attrs;
1503
1504	return 0;
1505
1506	error_free_scan_el_attrs:
1507	kfree(objp: iio_dev_opaque->legacy_scan_el_group.attrs);
1508	error_free_buffer_attrs:
1509	kfree(objp: iio_dev_opaque->legacy_buffer_group.attrs);
1510
1511	return ret;
1512	}
1513
1514	static void iio_buffer_unregister_legacy_sysfs_groups(struct iio_dev *indio_dev)
1515	{
1516	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1517
1518	kfree(objp: iio_dev_opaque->legacy_buffer_group.attrs);
1519	kfree(objp: iio_dev_opaque->legacy_scan_el_group.attrs);
1520	}
1521
1522	static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep)
1523	{
1524	struct iio_dev_buffer_pair *ib = filep->private_data;
1525	struct iio_dev *indio_dev = ib->indio_dev;
1526	struct iio_buffer *buffer = ib->buffer;
1527
1528	wake_up(&buffer->pollq);
1529
1530	kfree(objp: ib);
1531	clear_bit(IIO_BUSY_BIT_POS, addr: &buffer->flags);
1532	iio_device_put(indio_dev);
1533
1534	return 0;
1535	}
1536
1537	static const struct file_operations iio_buffer_chrdev_fileops = {
1538	.owner = THIS_MODULE,
1539	.llseek = noop_llseek,
1540	.read = iio_buffer_read,
1541	.write = iio_buffer_write,
1542	.poll = iio_buffer_poll,
1543	.release = iio_buffer_chrdev_release,
1544	};
1545
1546	static long iio_device_buffer_getfd(struct iio_dev *indio_dev, unsigned long arg)
1547	{
1548	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1549	int __user *ival = (int __user *)arg;
1550	struct iio_dev_buffer_pair *ib;
1551	struct iio_buffer *buffer;
1552	int fd, idx, ret;
1553
1554	if (copy_from_user(to: &idx, from: ival, n: sizeof(idx)))
1555	return -EFAULT;
1556
1557	if (idx >= iio_dev_opaque->attached_buffers_cnt)
1558	return -ENODEV;
1559
1560	iio_device_get(indio_dev);
1561
1562	buffer = iio_dev_opaque->attached_buffers[idx];
1563
1564	if (test_and_set_bit(IIO_BUSY_BIT_POS, addr: &buffer->flags)) {
1565	ret = -EBUSY;
1566	goto error_iio_dev_put;
1567	}
1568
1569	ib = kzalloc(size: sizeof(*ib), GFP_KERNEL);
1570	if (!ib) {
1571	ret = -ENOMEM;
1572	goto error_clear_busy_bit;
1573	}
1574
1575	ib->indio_dev = indio_dev;
1576	ib->buffer = buffer;
1577
1578	fd = anon_inode_getfd(name: "iio:buffer", fops: &iio_buffer_chrdev_fileops,
1579	priv: ib, O_RDWR | O_CLOEXEC);
1580	if (fd < 0) {
1581	ret = fd;
1582	goto error_free_ib;
1583	}
1584
1585	if (copy_to_user(to: ival, from: &fd, n: sizeof(fd))) {
1586	/*
1587	* "Leak" the fd, as there's not much we can do about this
1588	* anyway. 'fd' might have been closed already, as
1589	* anon_inode_getfd() called fd_install() on it, which made
1590	* it reachable by userland.
1591	*
1592	* Instead of allowing a malicious user to play tricks with
1593	* us, rely on the process exit path to do any necessary
1594	* cleanup, as in releasing the file, if still needed.
1595	*/
1596	return -EFAULT;
1597	}
1598
1599	return 0;
1600
1601	error_free_ib:
1602	kfree(objp: ib);
1603	error_clear_busy_bit:
1604	clear_bit(IIO_BUSY_BIT_POS, addr: &buffer->flags);
1605	error_iio_dev_put:
1606	iio_device_put(indio_dev);
1607	return ret;
1608	}
1609
1610	static long iio_device_buffer_ioctl(struct iio_dev *indio_dev, struct file *filp,
1611	unsigned int cmd, unsigned long arg)
1612	{
1613	switch (cmd) {
1614	case IIO_BUFFER_GET_FD_IOCTL:
1615	return iio_device_buffer_getfd(indio_dev, arg);
1616	default:
1617	return IIO_IOCTL_UNHANDLED;
1618	}
1619	}
1620
1621	static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
1622	struct iio_dev *indio_dev,
1623	int index)
1624	{
1625	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1626	struct iio_dev_attr *p;
1627	const struct iio_dev_attr *id_attr;
1628	struct attribute **attr;
1629	int ret, i, attrn, scan_el_attrcount, buffer_attrcount;
1630	const struct iio_chan_spec *channels;
1631
1632	buffer_attrcount = 0;
1633	if (buffer->attrs) {
1634	while (buffer->attrs[buffer_attrcount])
1635	buffer_attrcount++;
1636	}
1637	buffer_attrcount += ARRAY_SIZE(iio_buffer_attrs);
1638
1639	scan_el_attrcount = 0;
1640	INIT_LIST_HEAD(list: &buffer->buffer_attr_list);
1641	channels = indio_dev->channels;
1642	if (channels) {
1643	/* new magic */
1644	for (i = 0; i < indio_dev->num_channels; i++) {
1645	if (channels[i].scan_index < 0)
1646	continue;
1647
1648	/* Verify that sample bits fit into storage */
1649	if (channels[i].scan_type.storagebits <
1650	channels[i].scan_type.realbits +
1651	channels[i].scan_type.shift) {
1652	dev_err(&indio_dev->dev,
1653	"Channel %d storagebits (%d) < shifted realbits (%d + %d)\n",
1654	i, channels[i].scan_type.storagebits,
1655	channels[i].scan_type.realbits,
1656	channels[i].scan_type.shift);
1657	ret = -EINVAL;
1658	goto error_cleanup_dynamic;
1659	}
1660
1661	ret = iio_buffer_add_channel_sysfs(indio_dev, buffer,
1662	chan: &channels[i]);
1663	if (ret < 0)
1664	goto error_cleanup_dynamic;
1665	scan_el_attrcount += ret;
1666	if (channels[i].type == IIO_TIMESTAMP)
1667	iio_dev_opaque->scan_index_timestamp =
1668	channels[i].scan_index;
1669	}
1670	if (indio_dev->masklength && !buffer->scan_mask) {
1671	buffer->scan_mask = bitmap_zalloc(nbits: indio_dev->masklength,
1672	GFP_KERNEL);
1673	if (!buffer->scan_mask) {
1674	ret = -ENOMEM;
1675	goto error_cleanup_dynamic;
1676	}
1677	}
1678	}
1679
1680	attrn = buffer_attrcount + scan_el_attrcount;
1681	attr = kcalloc(n: attrn + 1, size: sizeof(*attr), GFP_KERNEL);
1682	if (!attr) {
1683	ret = -ENOMEM;
1684	goto error_free_scan_mask;
1685	}
1686
1687	memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
1688	if (!buffer->access->set_length)
1689	attr[0] = &dev_attr_length_ro.attr;
1690
1691	if (buffer->access->flags & INDIO_BUFFER_FLAG_FIXED_WATERMARK)
1692	attr[2] = &dev_attr_watermark_ro.attr;
1693
1694	if (buffer->attrs)
1695	for (i = 0, id_attr = buffer->attrs[i];
1696	(id_attr = buffer->attrs[i]); i++)
1697	attr[ARRAY_SIZE(iio_buffer_attrs) + i] =
1698	(struct attribute *)&id_attr->dev_attr.attr;
1699
1700	buffer->buffer_group.attrs = attr;
1701
1702	for (i = 0; i < buffer_attrcount; i++) {
1703	struct attribute *wrapped;
1704
1705	wrapped = iio_buffer_wrap_attr(buffer, attr: attr[i]);
1706	if (!wrapped) {
1707	ret = -ENOMEM;
1708	goto error_free_buffer_attrs;
1709	}
1710	attr[i] = wrapped;
1711	}
1712
1713	attrn = 0;
1714	list_for_each_entry(p, &buffer->buffer_attr_list, l)
1715	attr[attrn++] = &p->dev_attr.attr;
1716
1717	buffer->buffer_group.name = kasprintf(GFP_KERNEL, fmt: "buffer%d", index);
1718	if (!buffer->buffer_group.name) {
1719	ret = -ENOMEM;
1720	goto error_free_buffer_attrs;
1721	}
1722
1723	ret = iio_device_register_sysfs_group(indio_dev, group: &buffer->buffer_group);
1724	if (ret)
1725	goto error_free_buffer_attr_group_name;
1726
1727	/* we only need to register the legacy groups for the first buffer */
1728	if (index > 0)
1729	return 0;
1730
1731	ret = iio_buffer_register_legacy_sysfs_groups(indio_dev, buffer_attrs: attr,
1732	buffer_attrcount,
1733	scan_el_attrcount);
1734	if (ret)
1735	goto error_free_buffer_attr_group_name;
1736
1737	return 0;
1738
1739	error_free_buffer_attr_group_name:
1740	kfree(objp: buffer->buffer_group.name);
1741	error_free_buffer_attrs:
1742	kfree(objp: buffer->buffer_group.attrs);
1743	error_free_scan_mask:
1744	bitmap_free(bitmap: buffer->scan_mask);
1745	error_cleanup_dynamic:
1746	iio_free_chan_devattr_list(attr_list: &buffer->buffer_attr_list);
1747
1748	return ret;
1749	}
1750
1751	static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer,
1752	struct iio_dev *indio_dev,
1753	int index)
1754	{
1755	if (index == 0)
1756	iio_buffer_unregister_legacy_sysfs_groups(indio_dev);
1757	bitmap_free(bitmap: buffer->scan_mask);
1758	kfree(objp: buffer->buffer_group.name);
1759	kfree(objp: buffer->buffer_group.attrs);
1760	iio_free_chan_devattr_list(attr_list: &buffer->buffer_attr_list);
1761	}
1762
1763	int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
1764	{
1765	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1766	const struct iio_chan_spec *channels;
1767	struct iio_buffer *buffer;
1768	int ret, i, idx;
1769	size_t sz;
1770
1771	channels = indio_dev->channels;
1772	if (channels) {
1773	int ml = indio_dev->masklength;
1774
1775	for (i = 0; i < indio_dev->num_channels; i++)
1776	ml = max(ml, channels[i].scan_index + 1);
1777	indio_dev->masklength = ml;
1778	}
1779
1780	if (!iio_dev_opaque->attached_buffers_cnt)
1781	return 0;
1782
1783	for (idx = 0; idx < iio_dev_opaque->attached_buffers_cnt; idx++) {
1784	buffer = iio_dev_opaque->attached_buffers[idx];
1785	ret = __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev, index: idx);
1786	if (ret)
1787	goto error_unwind_sysfs_and_mask;
1788	}
1789
1790	sz = sizeof(*iio_dev_opaque->buffer_ioctl_handler);
1791	iio_dev_opaque->buffer_ioctl_handler = kzalloc(size: sz, GFP_KERNEL);
1792	if (!iio_dev_opaque->buffer_ioctl_handler) {
1793	ret = -ENOMEM;
1794	goto error_unwind_sysfs_and_mask;
1795	}
1796
1797	iio_dev_opaque->buffer_ioctl_handler->ioctl = iio_device_buffer_ioctl;
1798	iio_device_ioctl_handler_register(indio_dev,
1799	h: iio_dev_opaque->buffer_ioctl_handler);
1800
1801	return 0;
1802
1803	error_unwind_sysfs_and_mask:
1804	while (idx--) {
1805	buffer = iio_dev_opaque->attached_buffers[idx];
1806	__iio_buffer_free_sysfs_and_mask(buffer, indio_dev, index: idx);
1807	}
1808	return ret;
1809	}
1810
1811	void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev)
1812	{
1813	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1814	struct iio_buffer *buffer;
1815	int i;
1816
1817	if (!iio_dev_opaque->attached_buffers_cnt)
1818	return;
1819
1820	iio_device_ioctl_handler_unregister(h: iio_dev_opaque->buffer_ioctl_handler);
1821	kfree(objp: iio_dev_opaque->buffer_ioctl_handler);
1822
1823	for (i = iio_dev_opaque->attached_buffers_cnt - 1; i >= 0; i--) {
1824	buffer = iio_dev_opaque->attached_buffers[i];
1825	__iio_buffer_free_sysfs_and_mask(buffer, indio_dev, index: i);
1826	}
1827	}
1828
1829	/**
1830	* iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
1831	* @indio_dev: the iio device
1832	* @mask: scan mask to be checked
1833	*
1834	* Return true if exactly one bit is set in the scan mask, false otherwise. It
1835	* can be used for devices where only one channel can be active for sampling at
1836	* a time.
1837	*/
1838	bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
1839	const unsigned long *mask)
1840	{
1841	return bitmap_weight(src: mask, nbits: indio_dev->masklength) == 1;
1842	}
1843	EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
1844
1845	static const void *iio_demux(struct iio_buffer *buffer,
1846	const void *datain)
1847	{
1848	struct iio_demux_table *t;
1849
1850	if (list_empty(head: &buffer->demux_list))
1851	return datain;
1852	list_for_each_entry(t, &buffer->demux_list, l)
1853	memcpy(buffer->demux_bounce + t->to,
1854	datain + t->from, t->length);
1855
1856	return buffer->demux_bounce;
1857	}
1858
1859	static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
1860	{
1861	const void *dataout = iio_demux(buffer, datain: data);
1862	int ret;
1863
1864	ret = buffer->access->store_to(buffer, dataout);
1865	if (ret)
1866	return ret;
1867
1868	/*
1869	* We can't just test for watermark to decide if we wake the poll queue
1870	* because read may request less samples than the watermark.
1871	*/
1872	wake_up_interruptible_poll(&buffer->pollq, EPOLLIN | EPOLLRDNORM);
1873	return 0;
1874	}
1875
1876	/**
1877	* iio_push_to_buffers() - push to a registered buffer.
1878	* @indio_dev: iio_dev structure for device.
1879	* @data: Full scan.
1880	*/
1881	int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
1882	{
1883	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1884	int ret;
1885	struct iio_buffer *buf;
1886
1887	list_for_each_entry(buf, &iio_dev_opaque->buffer_list, buffer_list) {
1888	ret = iio_push_to_buffer(buffer: buf, data);
1889	if (ret < 0)
1890	return ret;
1891	}
1892
1893	return 0;
1894	}
1895	EXPORT_SYMBOL_GPL(iio_push_to_buffers);
1896
1897	/**
1898	* iio_push_to_buffers_with_ts_unaligned() - push to registered buffer,
1899	* no alignment or space requirements.
1900	* @indio_dev: iio_dev structure for device.
1901	* @data: channel data excluding the timestamp.
1902	* @data_sz: size of data.
1903	* @timestamp: timestamp for the sample data.
1904	*
1905	* This special variant of iio_push_to_buffers_with_timestamp() does
1906	* not require space for the timestamp, or 8 byte alignment of data.
1907	* It does however require an allocation on first call and additional
1908	* copies on all calls, so should be avoided if possible.
1909	*/
1910	int iio_push_to_buffers_with_ts_unaligned(struct iio_dev *indio_dev,
1911	const void *data,
1912	size_t data_sz,
1913	int64_t timestamp)
1914	{
1915	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
1916
1917	/*
1918	* Conservative estimate - we can always safely copy the minimum
1919	* of either the data provided or the length of the destination buffer.
1920	* This relaxed limit allows the calling drivers to be lax about
1921	* tracking the size of the data they are pushing, at the cost of
1922	* unnecessary copying of padding.
1923	*/
1924	data_sz = min_t(size_t, indio_dev->scan_bytes, data_sz);
1925	if (iio_dev_opaque->bounce_buffer_size != indio_dev->scan_bytes) {
1926	void *bb;
1927
1928	bb = devm_krealloc(dev: &indio_dev->dev,
1929	ptr: iio_dev_opaque->bounce_buffer,
1930	size: indio_dev->scan_bytes, GFP_KERNEL);
1931	if (!bb)
1932	return -ENOMEM;
1933	iio_dev_opaque->bounce_buffer = bb;
1934	iio_dev_opaque->bounce_buffer_size = indio_dev->scan_bytes;
1935	}
1936	memcpy(iio_dev_opaque->bounce_buffer, data, data_sz);
1937	return iio_push_to_buffers_with_timestamp(indio_dev,
1938	data: iio_dev_opaque->bounce_buffer,
1939	timestamp);
1940	}
1941	EXPORT_SYMBOL_GPL(iio_push_to_buffers_with_ts_unaligned);
1942
1943	/**
1944	* iio_buffer_release() - Free a buffer's resources
1945	* @ref: Pointer to the kref embedded in the iio_buffer struct
1946	*
1947	* This function is called when the last reference to the buffer has been
1948	* dropped. It will typically free all resources allocated by the buffer. Do not
1949	* call this function manually, always use iio_buffer_put() when done using a
1950	* buffer.
1951	*/
1952	static void iio_buffer_release(struct kref *ref)
1953	{
1954	struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
1955
1956	buffer->access->release(buffer);
1957	}
1958
1959	/**
1960	* iio_buffer_get() - Grab a reference to the buffer
1961	* @buffer: The buffer to grab a reference for, may be NULL
1962	*
1963	* Returns the pointer to the buffer that was passed into the function.
1964	*/
1965	struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
1966	{
1967	if (buffer)
1968	kref_get(kref: &buffer->ref);
1969
1970	return buffer;
1971	}
1972	EXPORT_SYMBOL_GPL(iio_buffer_get);
1973
1974	/**
1975	* iio_buffer_put() - Release the reference to the buffer
1976	* @buffer: The buffer to release the reference for, may be NULL
1977	*/
1978	void iio_buffer_put(struct iio_buffer *buffer)
1979	{
1980	if (buffer)
1981	kref_put(kref: &buffer->ref, release: iio_buffer_release);
1982	}
1983	EXPORT_SYMBOL_GPL(iio_buffer_put);
1984
1985	/**
1986	* iio_device_attach_buffer - Attach a buffer to a IIO device
1987	* @indio_dev: The device the buffer should be attached to
1988	* @buffer: The buffer to attach to the device
1989	*
1990	* Return 0 if successful, negative if error.
1991	*
1992	* This function attaches a buffer to a IIO device. The buffer stays attached to
1993	* the device until the device is freed. For legacy reasons, the first attached
1994	* buffer will also be assigned to 'indio_dev->buffer'.
1995	* The array allocated here, will be free'd via the iio_device_detach_buffers()
1996	* call which is handled by the iio_device_free().
1997	*/
1998	int iio_device_attach_buffer(struct iio_dev *indio_dev,
1999	struct iio_buffer *buffer)
2000	{
2001	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
2002	struct iio_buffer **new, **old = iio_dev_opaque->attached_buffers;
2003	unsigned int cnt = iio_dev_opaque->attached_buffers_cnt;
2004
2005	cnt++;
2006
2007	new = krealloc(objp: old, new_size: sizeof(*new) * cnt, GFP_KERNEL);
2008	if (!new)
2009	return -ENOMEM;
2010	iio_dev_opaque->attached_buffers = new;
2011
2012	buffer = iio_buffer_get(buffer);
2013
2014	/* first buffer is legacy; attach it to the IIO device directly */
2015	if (!indio_dev->buffer)
2016	indio_dev->buffer = buffer;
2017
2018	iio_dev_opaque->attached_buffers[cnt - 1] = buffer;
2019	iio_dev_opaque->attached_buffers_cnt = cnt;
2020
2021	return 0;
2022	}
2023	EXPORT_SYMBOL_GPL(iio_device_attach_buffer);
2024