xref: /openbmc/linux/drivers/iio/inkern.c (revision 6c33a6f4)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* The industrial I/O core in kernel channel mapping
3  *
4  * Copyright (c) 2011 Jonathan Cameron
5  */
6 #include <linux/err.h>
7 #include <linux/export.h>
8 #include <linux/slab.h>
9 #include <linux/mutex.h>
10 #include <linux/of.h>
11 
12 #include <linux/iio/iio.h>
13 #include "iio_core.h"
14 #include <linux/iio/machine.h>
15 #include <linux/iio/driver.h>
16 #include <linux/iio/consumer.h>
17 
18 struct iio_map_internal {
19 	struct iio_dev *indio_dev;
20 	struct iio_map *map;
21 	struct list_head l;
22 };
23 
24 static LIST_HEAD(iio_map_list);
25 static DEFINE_MUTEX(iio_map_list_lock);
26 
27 int iio_map_array_register(struct iio_dev *indio_dev, struct iio_map *maps)
28 {
29 	int i = 0, ret = 0;
30 	struct iio_map_internal *mapi;
31 
32 	if (maps == NULL)
33 		return 0;
34 
35 	mutex_lock(&iio_map_list_lock);
36 	while (maps[i].consumer_dev_name != NULL) {
37 		mapi = kzalloc(sizeof(*mapi), GFP_KERNEL);
38 		if (mapi == NULL) {
39 			ret = -ENOMEM;
40 			goto error_ret;
41 		}
42 		mapi->map = &maps[i];
43 		mapi->indio_dev = indio_dev;
44 		list_add_tail(&mapi->l, &iio_map_list);
45 		i++;
46 	}
47 error_ret:
48 	mutex_unlock(&iio_map_list_lock);
49 
50 	return ret;
51 }
52 EXPORT_SYMBOL_GPL(iio_map_array_register);
53 
54 
55 /*
56  * Remove all map entries associated with the given iio device
57  */
58 int iio_map_array_unregister(struct iio_dev *indio_dev)
59 {
60 	int ret = -ENODEV;
61 	struct iio_map_internal *mapi, *next;
62 
63 	mutex_lock(&iio_map_list_lock);
64 	list_for_each_entry_safe(mapi, next, &iio_map_list, l) {
65 		if (indio_dev == mapi->indio_dev) {
66 			list_del(&mapi->l);
67 			kfree(mapi);
68 			ret = 0;
69 		}
70 	}
71 	mutex_unlock(&iio_map_list_lock);
72 	return ret;
73 }
74 EXPORT_SYMBOL_GPL(iio_map_array_unregister);
75 
76 static const struct iio_chan_spec
77 *iio_chan_spec_from_name(const struct iio_dev *indio_dev, const char *name)
78 {
79 	int i;
80 	const struct iio_chan_spec *chan = NULL;
81 
82 	for (i = 0; i < indio_dev->num_channels; i++)
83 		if (indio_dev->channels[i].datasheet_name &&
84 		    strcmp(name, indio_dev->channels[i].datasheet_name) == 0) {
85 			chan = &indio_dev->channels[i];
86 			break;
87 		}
88 	return chan;
89 }
90 
91 #ifdef CONFIG_OF
92 
93 static int iio_dev_node_match(struct device *dev, const void *data)
94 {
95 	return dev->of_node == data && dev->type == &iio_device_type;
96 }
97 
98 /**
99  * __of_iio_simple_xlate - translate iiospec to the IIO channel index
100  * @indio_dev:	pointer to the iio_dev structure
101  * @iiospec:	IIO specifier as found in the device tree
102  *
103  * This is simple translation function, suitable for the most 1:1 mapped
104  * channels in IIO chips. This function performs only one sanity check:
105  * whether IIO index is less than num_channels (that is specified in the
106  * iio_dev).
107  */
108 static int __of_iio_simple_xlate(struct iio_dev *indio_dev,
109 				const struct of_phandle_args *iiospec)
110 {
111 	if (!iiospec->args_count)
112 		return 0;
113 
114 	if (iiospec->args[0] >= indio_dev->num_channels) {
115 		dev_err(&indio_dev->dev, "invalid channel index %u\n",
116 			iiospec->args[0]);
117 		return -EINVAL;
118 	}
119 
120 	return iiospec->args[0];
121 }
122 
123 static int __of_iio_channel_get(struct iio_channel *channel,
124 				struct device_node *np, int index)
125 {
126 	struct device *idev;
127 	struct iio_dev *indio_dev;
128 	int err;
129 	struct of_phandle_args iiospec;
130 
131 	err = of_parse_phandle_with_args(np, "io-channels",
132 					 "#io-channel-cells",
133 					 index, &iiospec);
134 	if (err)
135 		return err;
136 
137 	idev = bus_find_device(&iio_bus_type, NULL, iiospec.np,
138 			       iio_dev_node_match);
139 	of_node_put(iiospec.np);
140 	if (idev == NULL)
141 		return -EPROBE_DEFER;
142 
143 	indio_dev = dev_to_iio_dev(idev);
144 	channel->indio_dev = indio_dev;
145 	if (indio_dev->info->of_xlate)
146 		index = indio_dev->info->of_xlate(indio_dev, &iiospec);
147 	else
148 		index = __of_iio_simple_xlate(indio_dev, &iiospec);
149 	if (index < 0)
150 		goto err_put;
151 	channel->channel = &indio_dev->channels[index];
152 
153 	return 0;
154 
155 err_put:
156 	iio_device_put(indio_dev);
157 	return index;
158 }
159 
160 static struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
161 {
162 	struct iio_channel *channel;
163 	int err;
164 
165 	if (index < 0)
166 		return ERR_PTR(-EINVAL);
167 
168 	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
169 	if (channel == NULL)
170 		return ERR_PTR(-ENOMEM);
171 
172 	err = __of_iio_channel_get(channel, np, index);
173 	if (err)
174 		goto err_free_channel;
175 
176 	return channel;
177 
178 err_free_channel:
179 	kfree(channel);
180 	return ERR_PTR(err);
181 }
182 
183 static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
184 						      const char *name)
185 {
186 	struct iio_channel *chan = NULL;
187 
188 	/* Walk up the tree of devices looking for a matching iio channel */
189 	while (np) {
190 		int index = 0;
191 
192 		/*
193 		 * For named iio channels, first look up the name in the
194 		 * "io-channel-names" property.  If it cannot be found, the
195 		 * index will be an error code, and of_iio_channel_get()
196 		 * will fail.
197 		 */
198 		if (name)
199 			index = of_property_match_string(np, "io-channel-names",
200 							 name);
201 		chan = of_iio_channel_get(np, index);
202 		if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
203 			break;
204 		else if (name && index >= 0) {
205 			pr_err("ERROR: could not get IIO channel %pOF:%s(%i)\n",
206 				np, name ? name : "", index);
207 			return NULL;
208 		}
209 
210 		/*
211 		 * No matching IIO channel found on this node.
212 		 * If the parent node has a "io-channel-ranges" property,
213 		 * then we can try one of its channels.
214 		 */
215 		np = np->parent;
216 		if (np && !of_get_property(np, "io-channel-ranges", NULL))
217 			return NULL;
218 	}
219 
220 	return chan;
221 }
222 
223 static struct iio_channel *of_iio_channel_get_all(struct device *dev)
224 {
225 	struct iio_channel *chans;
226 	int i, mapind, nummaps = 0;
227 	int ret;
228 
229 	do {
230 		ret = of_parse_phandle_with_args(dev->of_node,
231 						 "io-channels",
232 						 "#io-channel-cells",
233 						 nummaps, NULL);
234 		if (ret < 0)
235 			break;
236 	} while (++nummaps);
237 
238 	if (nummaps == 0)	/* no error, return NULL to search map table */
239 		return NULL;
240 
241 	/* NULL terminated array to save passing size */
242 	chans = kcalloc(nummaps + 1, sizeof(*chans), GFP_KERNEL);
243 	if (chans == NULL)
244 		return ERR_PTR(-ENOMEM);
245 
246 	/* Search for OF matches */
247 	for (mapind = 0; mapind < nummaps; mapind++) {
248 		ret = __of_iio_channel_get(&chans[mapind], dev->of_node,
249 					   mapind);
250 		if (ret)
251 			goto error_free_chans;
252 	}
253 	return chans;
254 
255 error_free_chans:
256 	for (i = 0; i < mapind; i++)
257 		iio_device_put(chans[i].indio_dev);
258 	kfree(chans);
259 	return ERR_PTR(ret);
260 }
261 
262 #else /* CONFIG_OF */
263 
264 static inline struct iio_channel *
265 of_iio_channel_get_by_name(struct device_node *np, const char *name)
266 {
267 	return NULL;
268 }
269 
270 static inline struct iio_channel *of_iio_channel_get_all(struct device *dev)
271 {
272 	return NULL;
273 }
274 
275 #endif /* CONFIG_OF */
276 
277 static struct iio_channel *iio_channel_get_sys(const char *name,
278 					       const char *channel_name)
279 {
280 	struct iio_map_internal *c_i = NULL, *c = NULL;
281 	struct iio_channel *channel;
282 	int err;
283 
284 	if (name == NULL && channel_name == NULL)
285 		return ERR_PTR(-ENODEV);
286 
287 	/* first find matching entry the channel map */
288 	mutex_lock(&iio_map_list_lock);
289 	list_for_each_entry(c_i, &iio_map_list, l) {
290 		if ((name && strcmp(name, c_i->map->consumer_dev_name) != 0) ||
291 		    (channel_name &&
292 		     strcmp(channel_name, c_i->map->consumer_channel) != 0))
293 			continue;
294 		c = c_i;
295 		iio_device_get(c->indio_dev);
296 		break;
297 	}
298 	mutex_unlock(&iio_map_list_lock);
299 	if (c == NULL)
300 		return ERR_PTR(-ENODEV);
301 
302 	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
303 	if (channel == NULL) {
304 		err = -ENOMEM;
305 		goto error_no_mem;
306 	}
307 
308 	channel->indio_dev = c->indio_dev;
309 
310 	if (c->map->adc_channel_label) {
311 		channel->channel =
312 			iio_chan_spec_from_name(channel->indio_dev,
313 						c->map->adc_channel_label);
314 
315 		if (channel->channel == NULL) {
316 			err = -EINVAL;
317 			goto error_no_chan;
318 		}
319 	}
320 
321 	return channel;
322 
323 error_no_chan:
324 	kfree(channel);
325 error_no_mem:
326 	iio_device_put(c->indio_dev);
327 	return ERR_PTR(err);
328 }
329 
330 struct iio_channel *iio_channel_get(struct device *dev,
331 				    const char *channel_name)
332 {
333 	const char *name = dev ? dev_name(dev) : NULL;
334 	struct iio_channel *channel;
335 
336 	if (dev) {
337 		channel = of_iio_channel_get_by_name(dev->of_node,
338 						     channel_name);
339 		if (channel != NULL)
340 			return channel;
341 	}
342 
343 	return iio_channel_get_sys(name, channel_name);
344 }
345 EXPORT_SYMBOL_GPL(iio_channel_get);
346 
347 void iio_channel_release(struct iio_channel *channel)
348 {
349 	if (!channel)
350 		return;
351 	iio_device_put(channel->indio_dev);
352 	kfree(channel);
353 }
354 EXPORT_SYMBOL_GPL(iio_channel_release);
355 
356 static void devm_iio_channel_free(struct device *dev, void *res)
357 {
358 	struct iio_channel *channel = *(struct iio_channel **)res;
359 
360 	iio_channel_release(channel);
361 }
362 
363 static int devm_iio_channel_match(struct device *dev, void *res, void *data)
364 {
365 	struct iio_channel **r = res;
366 
367 	if (!r || !*r) {
368 		WARN_ON(!r || !*r);
369 		return 0;
370 	}
371 
372 	return *r == data;
373 }
374 
375 struct iio_channel *devm_iio_channel_get(struct device *dev,
376 					 const char *channel_name)
377 {
378 	struct iio_channel **ptr, *channel;
379 
380 	ptr = devres_alloc(devm_iio_channel_free, sizeof(*ptr), GFP_KERNEL);
381 	if (!ptr)
382 		return ERR_PTR(-ENOMEM);
383 
384 	channel = iio_channel_get(dev, channel_name);
385 	if (IS_ERR(channel)) {
386 		devres_free(ptr);
387 		return channel;
388 	}
389 
390 	*ptr = channel;
391 	devres_add(dev, ptr);
392 
393 	return channel;
394 }
395 EXPORT_SYMBOL_GPL(devm_iio_channel_get);
396 
397 void devm_iio_channel_release(struct device *dev, struct iio_channel *channel)
398 {
399 	WARN_ON(devres_release(dev, devm_iio_channel_free,
400 			       devm_iio_channel_match, channel));
401 }
402 EXPORT_SYMBOL_GPL(devm_iio_channel_release);
403 
404 struct iio_channel *iio_channel_get_all(struct device *dev)
405 {
406 	const char *name;
407 	struct iio_channel *chans;
408 	struct iio_map_internal *c = NULL;
409 	int nummaps = 0;
410 	int mapind = 0;
411 	int i, ret;
412 
413 	if (dev == NULL)
414 		return ERR_PTR(-EINVAL);
415 
416 	chans = of_iio_channel_get_all(dev);
417 	if (chans)
418 		return chans;
419 
420 	name = dev_name(dev);
421 
422 	mutex_lock(&iio_map_list_lock);
423 	/* first count the matching maps */
424 	list_for_each_entry(c, &iio_map_list, l)
425 		if (name && strcmp(name, c->map->consumer_dev_name) != 0)
426 			continue;
427 		else
428 			nummaps++;
429 
430 	if (nummaps == 0) {
431 		ret = -ENODEV;
432 		goto error_ret;
433 	}
434 
435 	/* NULL terminated array to save passing size */
436 	chans = kcalloc(nummaps + 1, sizeof(*chans), GFP_KERNEL);
437 	if (chans == NULL) {
438 		ret = -ENOMEM;
439 		goto error_ret;
440 	}
441 
442 	/* for each map fill in the chans element */
443 	list_for_each_entry(c, &iio_map_list, l) {
444 		if (name && strcmp(name, c->map->consumer_dev_name) != 0)
445 			continue;
446 		chans[mapind].indio_dev = c->indio_dev;
447 		chans[mapind].data = c->map->consumer_data;
448 		chans[mapind].channel =
449 			iio_chan_spec_from_name(chans[mapind].indio_dev,
450 						c->map->adc_channel_label);
451 		if (chans[mapind].channel == NULL) {
452 			ret = -EINVAL;
453 			goto error_free_chans;
454 		}
455 		iio_device_get(chans[mapind].indio_dev);
456 		mapind++;
457 	}
458 	if (mapind == 0) {
459 		ret = -ENODEV;
460 		goto error_free_chans;
461 	}
462 	mutex_unlock(&iio_map_list_lock);
463 
464 	return chans;
465 
466 error_free_chans:
467 	for (i = 0; i < nummaps; i++)
468 		iio_device_put(chans[i].indio_dev);
469 	kfree(chans);
470 error_ret:
471 	mutex_unlock(&iio_map_list_lock);
472 
473 	return ERR_PTR(ret);
474 }
475 EXPORT_SYMBOL_GPL(iio_channel_get_all);
476 
477 void iio_channel_release_all(struct iio_channel *channels)
478 {
479 	struct iio_channel *chan = &channels[0];
480 
481 	while (chan->indio_dev) {
482 		iio_device_put(chan->indio_dev);
483 		chan++;
484 	}
485 	kfree(channels);
486 }
487 EXPORT_SYMBOL_GPL(iio_channel_release_all);
488 
489 static void devm_iio_channel_free_all(struct device *dev, void *res)
490 {
491 	struct iio_channel *channels = *(struct iio_channel **)res;
492 
493 	iio_channel_release_all(channels);
494 }
495 
496 struct iio_channel *devm_iio_channel_get_all(struct device *dev)
497 {
498 	struct iio_channel **ptr, *channels;
499 
500 	ptr = devres_alloc(devm_iio_channel_free_all, sizeof(*ptr), GFP_KERNEL);
501 	if (!ptr)
502 		return ERR_PTR(-ENOMEM);
503 
504 	channels = iio_channel_get_all(dev);
505 	if (IS_ERR(channels)) {
506 		devres_free(ptr);
507 		return channels;
508 	}
509 
510 	*ptr = channels;
511 	devres_add(dev, ptr);
512 
513 	return channels;
514 }
515 EXPORT_SYMBOL_GPL(devm_iio_channel_get_all);
516 
517 void devm_iio_channel_release_all(struct device *dev,
518 				  struct iio_channel *channels)
519 {
520 	WARN_ON(devres_release(dev, devm_iio_channel_free_all,
521 			       devm_iio_channel_match, channels));
522 }
523 EXPORT_SYMBOL_GPL(devm_iio_channel_release_all);
524 
525 static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
526 	enum iio_chan_info_enum info)
527 {
528 	int unused;
529 	int vals[INDIO_MAX_RAW_ELEMENTS];
530 	int ret;
531 	int val_len = 2;
532 
533 	if (val2 == NULL)
534 		val2 = &unused;
535 
536 	if (!iio_channel_has_info(chan->channel, info))
537 		return -EINVAL;
538 
539 	if (chan->indio_dev->info->read_raw_multi) {
540 		ret = chan->indio_dev->info->read_raw_multi(chan->indio_dev,
541 					chan->channel, INDIO_MAX_RAW_ELEMENTS,
542 					vals, &val_len, info);
543 		*val = vals[0];
544 		*val2 = vals[1];
545 	} else
546 		ret = chan->indio_dev->info->read_raw(chan->indio_dev,
547 					chan->channel, val, val2, info);
548 
549 	return ret;
550 }
551 
552 int iio_read_channel_raw(struct iio_channel *chan, int *val)
553 {
554 	int ret;
555 
556 	mutex_lock(&chan->indio_dev->info_exist_lock);
557 	if (chan->indio_dev->info == NULL) {
558 		ret = -ENODEV;
559 		goto err_unlock;
560 	}
561 
562 	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
563 err_unlock:
564 	mutex_unlock(&chan->indio_dev->info_exist_lock);
565 
566 	return ret;
567 }
568 EXPORT_SYMBOL_GPL(iio_read_channel_raw);
569 
570 int iio_read_channel_average_raw(struct iio_channel *chan, int *val)
571 {
572 	int ret;
573 
574 	mutex_lock(&chan->indio_dev->info_exist_lock);
575 	if (chan->indio_dev->info == NULL) {
576 		ret = -ENODEV;
577 		goto err_unlock;
578 	}
579 
580 	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_AVERAGE_RAW);
581 err_unlock:
582 	mutex_unlock(&chan->indio_dev->info_exist_lock);
583 
584 	return ret;
585 }
586 EXPORT_SYMBOL_GPL(iio_read_channel_average_raw);
587 
588 static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
589 	int raw, int *processed, unsigned int scale)
590 {
591 	int scale_type, scale_val, scale_val2, offset;
592 	s64 raw64 = raw;
593 	int ret;
594 
595 	ret = iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_OFFSET);
596 	if (ret >= 0)
597 		raw64 += offset;
598 
599 	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
600 					IIO_CHAN_INFO_SCALE);
601 	if (scale_type < 0) {
602 		/*
603 		 * Just pass raw values as processed if no scaling is
604 		 * available.
605 		 */
606 		*processed = raw;
607 		return 0;
608 	}
609 
610 	switch (scale_type) {
611 	case IIO_VAL_INT:
612 		*processed = raw64 * scale_val;
613 		break;
614 	case IIO_VAL_INT_PLUS_MICRO:
615 		if (scale_val2 < 0)
616 			*processed = -raw64 * scale_val;
617 		else
618 			*processed = raw64 * scale_val;
619 		*processed += div_s64(raw64 * (s64)scale_val2 * scale,
620 				      1000000LL);
621 		break;
622 	case IIO_VAL_INT_PLUS_NANO:
623 		if (scale_val2 < 0)
624 			*processed = -raw64 * scale_val;
625 		else
626 			*processed = raw64 * scale_val;
627 		*processed += div_s64(raw64 * (s64)scale_val2 * scale,
628 				      1000000000LL);
629 		break;
630 	case IIO_VAL_FRACTIONAL:
631 		*processed = div_s64(raw64 * (s64)scale_val * scale,
632 				     scale_val2);
633 		break;
634 	case IIO_VAL_FRACTIONAL_LOG2:
635 		*processed = (raw64 * (s64)scale_val * scale) >> scale_val2;
636 		break;
637 	default:
638 		return -EINVAL;
639 	}
640 
641 	return 0;
642 }
643 
644 int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
645 	int *processed, unsigned int scale)
646 {
647 	int ret;
648 
649 	mutex_lock(&chan->indio_dev->info_exist_lock);
650 	if (chan->indio_dev->info == NULL) {
651 		ret = -ENODEV;
652 		goto err_unlock;
653 	}
654 
655 	ret = iio_convert_raw_to_processed_unlocked(chan, raw, processed,
656 							scale);
657 err_unlock:
658 	mutex_unlock(&chan->indio_dev->info_exist_lock);
659 
660 	return ret;
661 }
662 EXPORT_SYMBOL_GPL(iio_convert_raw_to_processed);
663 
664 int iio_read_channel_attribute(struct iio_channel *chan, int *val, int *val2,
665 			       enum iio_chan_info_enum attribute)
666 {
667 	int ret;
668 
669 	mutex_lock(&chan->indio_dev->info_exist_lock);
670 	if (chan->indio_dev->info == NULL) {
671 		ret = -ENODEV;
672 		goto err_unlock;
673 	}
674 
675 	ret = iio_channel_read(chan, val, val2, attribute);
676 err_unlock:
677 	mutex_unlock(&chan->indio_dev->info_exist_lock);
678 
679 	return ret;
680 }
681 EXPORT_SYMBOL_GPL(iio_read_channel_attribute);
682 
683 int iio_read_channel_offset(struct iio_channel *chan, int *val, int *val2)
684 {
685 	return iio_read_channel_attribute(chan, val, val2, IIO_CHAN_INFO_OFFSET);
686 }
687 EXPORT_SYMBOL_GPL(iio_read_channel_offset);
688 
689 int iio_read_channel_processed(struct iio_channel *chan, int *val)
690 {
691 	int ret;
692 
693 	mutex_lock(&chan->indio_dev->info_exist_lock);
694 	if (chan->indio_dev->info == NULL) {
695 		ret = -ENODEV;
696 		goto err_unlock;
697 	}
698 
699 	if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
700 		ret = iio_channel_read(chan, val, NULL,
701 				       IIO_CHAN_INFO_PROCESSED);
702 	} else {
703 		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
704 		if (ret < 0)
705 			goto err_unlock;
706 		ret = iio_convert_raw_to_processed_unlocked(chan, *val, val, 1);
707 	}
708 
709 err_unlock:
710 	mutex_unlock(&chan->indio_dev->info_exist_lock);
711 
712 	return ret;
713 }
714 EXPORT_SYMBOL_GPL(iio_read_channel_processed);
715 
716 int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
717 {
718 	return iio_read_channel_attribute(chan, val, val2, IIO_CHAN_INFO_SCALE);
719 }
720 EXPORT_SYMBOL_GPL(iio_read_channel_scale);
721 
722 static int iio_channel_read_avail(struct iio_channel *chan,
723 				  const int **vals, int *type, int *length,
724 				  enum iio_chan_info_enum info)
725 {
726 	if (!iio_channel_has_available(chan->channel, info))
727 		return -EINVAL;
728 
729 	return chan->indio_dev->info->read_avail(chan->indio_dev, chan->channel,
730 						 vals, type, length, info);
731 }
732 
733 int iio_read_avail_channel_attribute(struct iio_channel *chan,
734 				     const int **vals, int *type, int *length,
735 				     enum iio_chan_info_enum attribute)
736 {
737 	int ret;
738 
739 	mutex_lock(&chan->indio_dev->info_exist_lock);
740 	if (!chan->indio_dev->info) {
741 		ret = -ENODEV;
742 		goto err_unlock;
743 	}
744 
745 	ret = iio_channel_read_avail(chan, vals, type, length, attribute);
746 err_unlock:
747 	mutex_unlock(&chan->indio_dev->info_exist_lock);
748 
749 	return ret;
750 }
751 EXPORT_SYMBOL_GPL(iio_read_avail_channel_attribute);
752 
753 int iio_read_avail_channel_raw(struct iio_channel *chan,
754 			       const int **vals, int *length)
755 {
756 	int ret;
757 	int type;
758 
759 	ret = iio_read_avail_channel_attribute(chan, vals, &type, length,
760 					 IIO_CHAN_INFO_RAW);
761 
762 	if (ret >= 0 && type != IIO_VAL_INT)
763 		/* raw values are assumed to be IIO_VAL_INT */
764 		ret = -EINVAL;
765 
766 	return ret;
767 }
768 EXPORT_SYMBOL_GPL(iio_read_avail_channel_raw);
769 
770 static int iio_channel_read_max(struct iio_channel *chan,
771 				int *val, int *val2, int *type,
772 				enum iio_chan_info_enum info)
773 {
774 	int unused;
775 	const int *vals;
776 	int length;
777 	int ret;
778 
779 	if (!val2)
780 		val2 = &unused;
781 
782 	ret = iio_channel_read_avail(chan, &vals, type, &length, info);
783 	switch (ret) {
784 	case IIO_AVAIL_RANGE:
785 		switch (*type) {
786 		case IIO_VAL_INT:
787 			*val = vals[2];
788 			break;
789 		default:
790 			*val = vals[4];
791 			*val2 = vals[5];
792 		}
793 		return 0;
794 
795 	case IIO_AVAIL_LIST:
796 		if (length <= 0)
797 			return -EINVAL;
798 		switch (*type) {
799 		case IIO_VAL_INT:
800 			*val = vals[--length];
801 			while (length) {
802 				if (vals[--length] > *val)
803 					*val = vals[length];
804 			}
805 			break;
806 		default:
807 			/* FIXME: learn about max for other iio values */
808 			return -EINVAL;
809 		}
810 		return 0;
811 
812 	default:
813 		return ret;
814 	}
815 }
816 
817 int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
818 {
819 	int ret;
820 	int type;
821 
822 	mutex_lock(&chan->indio_dev->info_exist_lock);
823 	if (!chan->indio_dev->info) {
824 		ret = -ENODEV;
825 		goto err_unlock;
826 	}
827 
828 	ret = iio_channel_read_max(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
829 err_unlock:
830 	mutex_unlock(&chan->indio_dev->info_exist_lock);
831 
832 	return ret;
833 }
834 EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);
835 
836 int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
837 {
838 	int ret = 0;
839 	/* Need to verify underlying driver has not gone away */
840 
841 	mutex_lock(&chan->indio_dev->info_exist_lock);
842 	if (chan->indio_dev->info == NULL) {
843 		ret = -ENODEV;
844 		goto err_unlock;
845 	}
846 
847 	*type = chan->channel->type;
848 err_unlock:
849 	mutex_unlock(&chan->indio_dev->info_exist_lock);
850 
851 	return ret;
852 }
853 EXPORT_SYMBOL_GPL(iio_get_channel_type);
854 
855 static int iio_channel_write(struct iio_channel *chan, int val, int val2,
856 			     enum iio_chan_info_enum info)
857 {
858 	return chan->indio_dev->info->write_raw(chan->indio_dev,
859 						chan->channel, val, val2, info);
860 }
861 
862 int iio_write_channel_attribute(struct iio_channel *chan, int val, int val2,
863 				enum iio_chan_info_enum attribute)
864 {
865 	int ret;
866 
867 	mutex_lock(&chan->indio_dev->info_exist_lock);
868 	if (chan->indio_dev->info == NULL) {
869 		ret = -ENODEV;
870 		goto err_unlock;
871 	}
872 
873 	ret = iio_channel_write(chan, val, val2, attribute);
874 err_unlock:
875 	mutex_unlock(&chan->indio_dev->info_exist_lock);
876 
877 	return ret;
878 }
879 EXPORT_SYMBOL_GPL(iio_write_channel_attribute);
880 
881 int iio_write_channel_raw(struct iio_channel *chan, int val)
882 {
883 	return iio_write_channel_attribute(chan, val, 0, IIO_CHAN_INFO_RAW);
884 }
885 EXPORT_SYMBOL_GPL(iio_write_channel_raw);
886 
887 unsigned int iio_get_channel_ext_info_count(struct iio_channel *chan)
888 {
889 	const struct iio_chan_spec_ext_info *ext_info;
890 	unsigned int i = 0;
891 
892 	if (!chan->channel->ext_info)
893 		return i;
894 
895 	for (ext_info = chan->channel->ext_info; ext_info->name; ext_info++)
896 		++i;
897 
898 	return i;
899 }
900 EXPORT_SYMBOL_GPL(iio_get_channel_ext_info_count);
901 
902 static const struct iio_chan_spec_ext_info *iio_lookup_ext_info(
903 						const struct iio_channel *chan,
904 						const char *attr)
905 {
906 	const struct iio_chan_spec_ext_info *ext_info;
907 
908 	if (!chan->channel->ext_info)
909 		return NULL;
910 
911 	for (ext_info = chan->channel->ext_info; ext_info->name; ++ext_info) {
912 		if (!strcmp(attr, ext_info->name))
913 			return ext_info;
914 	}
915 
916 	return NULL;
917 }
918 
919 ssize_t iio_read_channel_ext_info(struct iio_channel *chan,
920 				  const char *attr, char *buf)
921 {
922 	const struct iio_chan_spec_ext_info *ext_info;
923 
924 	ext_info = iio_lookup_ext_info(chan, attr);
925 	if (!ext_info)
926 		return -EINVAL;
927 
928 	return ext_info->read(chan->indio_dev, ext_info->private,
929 			      chan->channel, buf);
930 }
931 EXPORT_SYMBOL_GPL(iio_read_channel_ext_info);
932 
933 ssize_t iio_write_channel_ext_info(struct iio_channel *chan, const char *attr,
934 				   const char *buf, size_t len)
935 {
936 	const struct iio_chan_spec_ext_info *ext_info;
937 
938 	ext_info = iio_lookup_ext_info(chan, attr);
939 	if (!ext_info)
940 		return -EINVAL;
941 
942 	return ext_info->write(chan->indio_dev, ext_info->private,
943 			       chan->channel, buf, len);
944 }
945 EXPORT_SYMBOL_GPL(iio_write_channel_ext_info);
946