Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 942 insertions, 0 deletions

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
new file mode 100644
index 000000000..c32b2577d
--- /dev/null
+++ b/drivers/iio/inkern.c
@@ -0,0 +1,942 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* The industrial I/O core in kernel channel mapping
+ *
+ * Copyright (c) 2011 Jonathan Cameron
+ */
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+
+#include <linux/iio/iio.h>
+#include "iio_core.h"
+#include <linux/iio/machine.h>
+#include <linux/iio/driver.h>
+#include <linux/iio/consumer.h>
+
+struct iio_map_internal {
+	struct iio_dev *indio_dev;
+	struct iio_map *map;
+	struct list_head l;
+};
+
+static LIST_HEAD(iio_map_list);
+static DEFINE_MUTEX(iio_map_list_lock);
+
+int iio_map_array_register(struct iio_dev *indio_dev, struct iio_map *maps)
+{
+	int i = 0, ret = 0;
+	struct iio_map_internal *mapi;
+
+	if (maps == NULL)
+		return 0;
+
+	mutex_lock(&iio_map_list_lock);
+	while (maps[i].consumer_dev_name != NULL) {
+		mapi = kzalloc(sizeof(*mapi), GFP_KERNEL);
+		if (mapi == NULL) {
+			ret = -ENOMEM;
+			goto error_ret;
+		}
+		mapi->map = &maps[i];
+		mapi->indio_dev = indio_dev;
+		list_add_tail(&mapi->l, &iio_map_list);
+		i++;
+	}
+error_ret:
+	mutex_unlock(&iio_map_list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_map_array_register);
+
+
+/*
+ * Remove all map entries associated with the given iio device
+ */
+int iio_map_array_unregister(struct iio_dev *indio_dev)
+{
+	int ret = -ENODEV;
+	struct iio_map_internal *mapi, *next;
+
+	mutex_lock(&iio_map_list_lock);
+	list_for_each_entry_safe(mapi, next, &iio_map_list, l) {
+		if (indio_dev == mapi->indio_dev) {
+			list_del(&mapi->l);
+			kfree(mapi);
+			ret = 0;
+		}
+	}
+	mutex_unlock(&iio_map_list_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_map_array_unregister);
+
+static const struct iio_chan_spec
+*iio_chan_spec_from_name(const struct iio_dev *indio_dev, const char *name)
+{
+	int i;
+	const struct iio_chan_spec *chan = NULL;
+
+	for (i = 0; i < indio_dev->num_channels; i++)
+		if (indio_dev->channels[i].datasheet_name &&
+		    strcmp(name, indio_dev->channels[i].datasheet_name) == 0) {
+			chan = &indio_dev->channels[i];
+			break;
+		}
+	return chan;
+}
+
+#ifdef CONFIG_OF
+
+static int iio_dev_node_match(struct device *dev, const void *data)
+{
+	return dev->of_node == data && dev->type == &iio_device_type;
+}
+
+/**
+ * __of_iio_simple_xlate - translate iiospec to the IIO channel index
+ * @indio_dev:	pointer to the iio_dev structure
+ * @iiospec:	IIO specifier as found in the device tree
+ *
+ * This is simple translation function, suitable for the most 1:1 mapped
+ * channels in IIO chips. This function performs only one sanity check:
+ * whether IIO index is less than num_channels (that is specified in the
+ * iio_dev).
+ */
+static int __of_iio_simple_xlate(struct iio_dev *indio_dev,
+				const struct of_phandle_args *iiospec)
+{
+	if (!iiospec->args_count)
+		return 0;
+
+	if (iiospec->args[0] >= indio_dev->num_channels) {
+		dev_err(&indio_dev->dev, "invalid channel index %u\n",
+			iiospec->args[0]);
+		return -EINVAL;
+	}
+
+	return iiospec->args[0];
+}
+
+static int __of_iio_channel_get(struct iio_channel *channel,
+				struct device_node *np, int index)
+{
+	struct device *idev;
+	struct iio_dev *indio_dev;
+	int err;
+	struct of_phandle_args iiospec;
+
+	err = of_parse_phandle_with_args(np, "io-channels",
+					 "#io-channel-cells",
+					 index, &iiospec);
+	if (err)
+		return err;
+
+	idev = bus_find_device(&iio_bus_type, NULL, iiospec.np,
+			       iio_dev_node_match);
+	if (idev == NULL) {
+		of_node_put(iiospec.np);
+		return -EPROBE_DEFER;
+	}
+
+	indio_dev = dev_to_iio_dev(idev);
+	channel->indio_dev = indio_dev;
+	if (indio_dev->info->of_xlate)
+		index = indio_dev->info->of_xlate(indio_dev, &iiospec);
+	else
+		index = __of_iio_simple_xlate(indio_dev, &iiospec);
+	of_node_put(iiospec.np);
+	if (index < 0)
+		goto err_put;
+	channel->channel = &indio_dev->channels[index];
+
+	return 0;
+
+err_put:
+	iio_device_put(indio_dev);
+	return index;
+}
+
+static struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
+{
+	struct iio_channel *channel;
+	int err;
+
+	if (index < 0)
+		return ERR_PTR(-EINVAL);
+
+	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+	if (channel == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	err = __of_iio_channel_get(channel, np, index);
+	if (err)
+		goto err_free_channel;
+
+	return channel;
+
+err_free_channel:
+	kfree(channel);
+	return ERR_PTR(err);
+}
+
+static struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
+						      const char *name)
+{
+	struct iio_channel *chan = NULL;
+
+	/* Walk up the tree of devices looking for a matching iio channel */
+	while (np) {
+		int index = 0;
+
+		/*
+		 * For named iio channels, first look up the name in the
+		 * "io-channel-names" property.  If it cannot be found, the
+		 * index will be an error code, and of_iio_channel_get()
+		 * will fail.
+		 */
+		if (name)
+			index = of_property_match_string(np, "io-channel-names",
+							 name);
+		chan = of_iio_channel_get(np, index);
+		if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
+			break;
+		else if (name && index >= 0) {
+			pr_err("ERROR: could not get IIO channel %pOF:%s(%i)\n",
+				np, name ? name : "", index);
+			return NULL;
+		}
+
+		/*
+		 * No matching IIO channel found on this node.
+		 * If the parent node has a "io-channel-ranges" property,
+		 * then we can try one of its channels.
+		 */
+		np = np->parent;
+		if (np && !of_get_property(np, "io-channel-ranges", NULL))
+			return NULL;
+	}
+
+	return chan;
+}
+
+static struct iio_channel *of_iio_channel_get_all(struct device *dev)
+{
+	struct iio_channel *chans;
+	int i, mapind, nummaps = 0;
+	int ret;
+
+	do {
+		ret = of_parse_phandle_with_args(dev->of_node,
+						 "io-channels",
+						 "#io-channel-cells",
+						 nummaps, NULL);
+		if (ret < 0)
+			break;
+	} while (++nummaps);
+
+	if (nummaps == 0)	/* no error, return NULL to search map table */
+		return NULL;
+
+	/* NULL terminated array to save passing size */
+	chans = kcalloc(nummaps + 1, sizeof(*chans), GFP_KERNEL);
+	if (chans == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	/* Search for OF matches */
+	for (mapind = 0; mapind < nummaps; mapind++) {
+		ret = __of_iio_channel_get(&chans[mapind], dev->of_node,
+					   mapind);
+		if (ret)
+			goto error_free_chans;
+	}
+	return chans;
+
+error_free_chans:
+	for (i = 0; i < mapind; i++)
+		iio_device_put(chans[i].indio_dev);
+	kfree(chans);
+	return ERR_PTR(ret);
+}
+
+#else /* CONFIG_OF */
+
+static inline struct iio_channel *
+of_iio_channel_get_by_name(struct device_node *np, const char *name)
+{
+	return NULL;
+}
+
+static inline struct iio_channel *of_iio_channel_get_all(struct device *dev)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_OF */
+
+static struct iio_channel *iio_channel_get_sys(const char *name,
+					       const char *channel_name)
+{
+	struct iio_map_internal *c_i = NULL, *c = NULL;
+	struct iio_channel *channel;
+	int err;
+
+	if (name == NULL && channel_name == NULL)
+		return ERR_PTR(-ENODEV);
+
+	/* first find matching entry the channel map */
+	mutex_lock(&iio_map_list_lock);
+	list_for_each_entry(c_i, &iio_map_list, l) {
+		if ((name && strcmp(name, c_i->map->consumer_dev_name) != 0) ||
+		    (channel_name &&
+		     strcmp(channel_name, c_i->map->consumer_channel) != 0))
+			continue;
+		c = c_i;
+		iio_device_get(c->indio_dev);
+		break;
+	}
+	mutex_unlock(&iio_map_list_lock);
+	if (c == NULL)
+		return ERR_PTR(-ENODEV);
+
+	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+	if (channel == NULL) {
+		err = -ENOMEM;
+		goto error_no_mem;
+	}
+
+	channel->indio_dev = c->indio_dev;
+
+	if (c->map->adc_channel_label) {
+		channel->channel =
+			iio_chan_spec_from_name(channel->indio_dev,
+						c->map->adc_channel_label);
+
+		if (channel->channel == NULL) {
+			err = -EINVAL;
+			goto error_no_chan;
+		}
+	}
+
+	return channel;
+
+error_no_chan:
+	kfree(channel);
+error_no_mem:
+	iio_device_put(c->indio_dev);
+	return ERR_PTR(err);
+}
+
+struct iio_channel *iio_channel_get(struct device *dev,
+				    const char *channel_name)
+{
+	const char *name = dev ? dev_name(dev) : NULL;
+	struct iio_channel *channel;
+
+	if (dev) {
+		channel = of_iio_channel_get_by_name(dev->of_node,
+						     channel_name);
+		if (channel != NULL)
+			return channel;
+	}
+
+	return iio_channel_get_sys(name, channel_name);
+}
+EXPORT_SYMBOL_GPL(iio_channel_get);
+
+void iio_channel_release(struct iio_channel *channel)
+{
+	if (!channel)
+		return;
+	iio_device_put(channel->indio_dev);
+	kfree(channel);
+}
+EXPORT_SYMBOL_GPL(iio_channel_release);
+
+static void devm_iio_channel_free(struct device *dev, void *res)
+{
+	struct iio_channel *channel = *(struct iio_channel **)res;
+
+	iio_channel_release(channel);
+}
+
+struct iio_channel *devm_iio_channel_get(struct device *dev,
+					 const char *channel_name)
+{
+	struct iio_channel **ptr, *channel;
+
+	ptr = devres_alloc(devm_iio_channel_free, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	channel = iio_channel_get(dev, channel_name);
+	if (IS_ERR(channel)) {
+		devres_free(ptr);
+		return channel;
+	}
+
+	*ptr = channel;
+	devres_add(dev, ptr);
+
+	return channel;
+}
+EXPORT_SYMBOL_GPL(devm_iio_channel_get);
+
+struct iio_channel *iio_channel_get_all(struct device *dev)
+{
+	const char *name;
+	struct iio_channel *chans;
+	struct iio_map_internal *c = NULL;
+	int nummaps = 0;
+	int mapind = 0;
+	int i, ret;
+
+	if (dev == NULL)
+		return ERR_PTR(-EINVAL);
+
+	chans = of_iio_channel_get_all(dev);
+	if (chans)
+		return chans;
+
+	name = dev_name(dev);
+
+	mutex_lock(&iio_map_list_lock);
+	/* first count the matching maps */
+	list_for_each_entry(c, &iio_map_list, l)
+		if (name && strcmp(name, c->map->consumer_dev_name) != 0)
+			continue;
+		else
+			nummaps++;
+
+	if (nummaps == 0) {
+		ret = -ENODEV;
+		goto error_ret;
+	}
+
+	/* NULL terminated array to save passing size */
+	chans = kcalloc(nummaps + 1, sizeof(*chans), GFP_KERNEL);
+	if (chans == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	/* for each map fill in the chans element */
+	list_for_each_entry(c, &iio_map_list, l) {
+		if (name && strcmp(name, c->map->consumer_dev_name) != 0)
+			continue;
+		chans[mapind].indio_dev = c->indio_dev;
+		chans[mapind].data = c->map->consumer_data;
+		chans[mapind].channel =
+			iio_chan_spec_from_name(chans[mapind].indio_dev,
+						c->map->adc_channel_label);
+		if (chans[mapind].channel == NULL) {
+			ret = -EINVAL;
+			goto error_free_chans;
+		}
+		iio_device_get(chans[mapind].indio_dev);
+		mapind++;
+	}
+	if (mapind == 0) {
+		ret = -ENODEV;
+		goto error_free_chans;
+	}
+	mutex_unlock(&iio_map_list_lock);
+
+	return chans;
+
+error_free_chans:
+	for (i = 0; i < nummaps; i++)
+		iio_device_put(chans[i].indio_dev);
+	kfree(chans);
+error_ret:
+	mutex_unlock(&iio_map_list_lock);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(iio_channel_get_all);
+
+void iio_channel_release_all(struct iio_channel *channels)
+{
+	struct iio_channel *chan = &channels[0];
+
+	while (chan->indio_dev) {
+		iio_device_put(chan->indio_dev);
+		chan++;
+	}
+	kfree(channels);
+}
+EXPORT_SYMBOL_GPL(iio_channel_release_all);
+
+static void devm_iio_channel_free_all(struct device *dev, void *res)
+{
+	struct iio_channel *channels = *(struct iio_channel **)res;
+
+	iio_channel_release_all(channels);
+}
+
+struct iio_channel *devm_iio_channel_get_all(struct device *dev)
+{
+	struct iio_channel **ptr, *channels;
+
+	ptr = devres_alloc(devm_iio_channel_free_all, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	channels = iio_channel_get_all(dev);
+	if (IS_ERR(channels)) {
+		devres_free(ptr);
+		return channels;
+	}
+
+	*ptr = channels;
+	devres_add(dev, ptr);
+
+	return channels;
+}
+EXPORT_SYMBOL_GPL(devm_iio_channel_get_all);
+
+static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
+	enum iio_chan_info_enum info)
+{
+	int unused;
+	int vals[INDIO_MAX_RAW_ELEMENTS];
+	int ret;
+	int val_len = 2;
+
+	if (val2 == NULL)
+		val2 = &unused;
+
+	if (!iio_channel_has_info(chan->channel, info))
+		return -EINVAL;
+
+	if (chan->indio_dev->info->read_raw_multi) {
+		ret = chan->indio_dev->info->read_raw_multi(chan->indio_dev,
+					chan->channel, INDIO_MAX_RAW_ELEMENTS,
+					vals, &val_len, info);
+		*val = vals[0];
+		*val2 = vals[1];
+	} else
+		ret = chan->indio_dev->info->read_raw(chan->indio_dev,
+					chan->channel, val, val2, info);
+
+	return ret;
+}
+
+int iio_read_channel_raw(struct iio_channel *chan, int *val)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_raw);
+
+int iio_read_channel_average_raw(struct iio_channel *chan, int *val)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_AVERAGE_RAW);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_average_raw);
+
+static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
+	int raw, int *processed, unsigned int scale)
+{
+	int scale_type, scale_val, scale_val2;
+	int offset_type, offset_val, offset_val2;
+	s64 raw64 = raw;
+
+	offset_type = iio_channel_read(chan, &offset_val, &offset_val2,
+				       IIO_CHAN_INFO_OFFSET);
+	if (offset_type >= 0) {
+		switch (offset_type) {
+		case IIO_VAL_INT:
+			break;
+		case IIO_VAL_INT_PLUS_MICRO:
+		case IIO_VAL_INT_PLUS_NANO:
+			/*
+			 * Both IIO_VAL_INT_PLUS_MICRO and IIO_VAL_INT_PLUS_NANO
+			 * implicitely truncate the offset to it's integer form.
+			 */
+			break;
+		case IIO_VAL_FRACTIONAL:
+			offset_val /= offset_val2;
+			break;
+		case IIO_VAL_FRACTIONAL_LOG2:
+			offset_val >>= offset_val2;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		raw64 += offset_val;
+	}
+
+	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
+					IIO_CHAN_INFO_SCALE);
+	if (scale_type < 0) {
+		/*
+		 * If no channel scaling is available apply consumer scale to
+		 * raw value and return.
+		 */
+		*processed = raw * scale;
+		return 0;
+	}
+
+	switch (scale_type) {
+	case IIO_VAL_INT:
+		*processed = raw64 * scale_val * scale;
+		break;
+	case IIO_VAL_INT_PLUS_MICRO:
+		if (scale_val2 < 0)
+			*processed = -raw64 * scale_val;
+		else
+			*processed = raw64 * scale_val;
+		*processed += div_s64(raw64 * (s64)scale_val2 * scale,
+				      1000000LL);
+		break;
+	case IIO_VAL_INT_PLUS_NANO:
+		if (scale_val2 < 0)
+			*processed = -raw64 * scale_val;
+		else
+			*processed = raw64 * scale_val;
+		*processed += div_s64(raw64 * (s64)scale_val2 * scale,
+				      1000000000LL);
+		break;
+	case IIO_VAL_FRACTIONAL:
+		*processed = div_s64(raw64 * (s64)scale_val * scale,
+				     scale_val2);
+		break;
+	case IIO_VAL_FRACTIONAL_LOG2:
+		*processed = (raw64 * (s64)scale_val * scale) >> scale_val2;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
+	int *processed, unsigned int scale)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_convert_raw_to_processed_unlocked(chan, raw, processed,
+							scale);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_convert_raw_to_processed);
+
+int iio_read_channel_attribute(struct iio_channel *chan, int *val, int *val2,
+			       enum iio_chan_info_enum attribute)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read(chan, val, val2, attribute);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_attribute);
+
+int iio_read_channel_offset(struct iio_channel *chan, int *val, int *val2)
+{
+	return iio_read_channel_attribute(chan, val, val2, IIO_CHAN_INFO_OFFSET);
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_offset);
+
+int iio_read_channel_processed(struct iio_channel *chan, int *val)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
+		ret = iio_channel_read(chan, val, NULL,
+				       IIO_CHAN_INFO_PROCESSED);
+	} else {
+		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
+		if (ret < 0)
+			goto err_unlock;
+		ret = iio_convert_raw_to_processed_unlocked(chan, *val, val, 1);
+	}
+
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_processed);
+
+int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
+{
+	return iio_read_channel_attribute(chan, val, val2, IIO_CHAN_INFO_SCALE);
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_scale);
+
+static int iio_channel_read_avail(struct iio_channel *chan,
+				  const int **vals, int *type, int *length,
+				  enum iio_chan_info_enum info)
+{
+	if (!iio_channel_has_available(chan->channel, info))
+		return -EINVAL;
+
+	return chan->indio_dev->info->read_avail(chan->indio_dev, chan->channel,
+						 vals, type, length, info);
+}
+
+int iio_read_avail_channel_attribute(struct iio_channel *chan,
+				     const int **vals, int *type, int *length,
+				     enum iio_chan_info_enum attribute)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (!chan->indio_dev->info) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read_avail(chan, vals, type, length, attribute);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_avail_channel_attribute);
+
+int iio_read_avail_channel_raw(struct iio_channel *chan,
+			       const int **vals, int *length)
+{
+	int ret;
+	int type;
+
+	ret = iio_read_avail_channel_attribute(chan, vals, &type, length,
+					 IIO_CHAN_INFO_RAW);
+
+	if (ret >= 0 && type != IIO_VAL_INT)
+		/* raw values are assumed to be IIO_VAL_INT */
+		ret = -EINVAL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_avail_channel_raw);
+
+static int iio_channel_read_max(struct iio_channel *chan,
+				int *val, int *val2, int *type,
+				enum iio_chan_info_enum info)
+{
+	int unused;
+	const int *vals;
+	int length;
+	int ret;
+
+	if (!val2)
+		val2 = &unused;
+
+	ret = iio_channel_read_avail(chan, &vals, type, &length, info);
+	switch (ret) {
+	case IIO_AVAIL_RANGE:
+		switch (*type) {
+		case IIO_VAL_INT:
+			*val = vals[2];
+			break;
+		default:
+			*val = vals[4];
+			*val2 = vals[5];
+		}
+		return 0;
+
+	case IIO_AVAIL_LIST:
+		if (length <= 0)
+			return -EINVAL;
+		switch (*type) {
+		case IIO_VAL_INT:
+			*val = vals[--length];
+			while (length) {
+				if (vals[--length] > *val)
+					*val = vals[length];
+			}
+			break;
+		default:
+			/* FIXME: learn about max for other iio values */
+			return -EINVAL;
+		}
+		return 0;
+
+	default:
+		return ret;
+	}
+}
+
+int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
+{
+	int ret;
+	int type;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (!chan->indio_dev->info) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_read_max(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);
+
+int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
+{
+	int ret = 0;
+	/* Need to verify underlying driver has not gone away */
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	*type = chan->channel->type;
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_get_channel_type);
+
+static int iio_channel_write(struct iio_channel *chan, int val, int val2,
+			     enum iio_chan_info_enum info)
+{
+	return chan->indio_dev->info->write_raw(chan->indio_dev,
+						chan->channel, val, val2, info);
+}
+
+int iio_write_channel_attribute(struct iio_channel *chan, int val, int val2,
+				enum iio_chan_info_enum attribute)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_channel_write(chan, val, val2, attribute);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_write_channel_attribute);
+
+int iio_write_channel_raw(struct iio_channel *chan, int val)
+{
+	return iio_write_channel_attribute(chan, val, 0, IIO_CHAN_INFO_RAW);
+}
+EXPORT_SYMBOL_GPL(iio_write_channel_raw);
+
+unsigned int iio_get_channel_ext_info_count(struct iio_channel *chan)
+{
+	const struct iio_chan_spec_ext_info *ext_info;
+	unsigned int i = 0;
+
+	if (!chan->channel->ext_info)
+		return i;
+
+	for (ext_info = chan->channel->ext_info; ext_info->name; ext_info++)
+		++i;
+
+	return i;
+}
+EXPORT_SYMBOL_GPL(iio_get_channel_ext_info_count);
+
+static const struct iio_chan_spec_ext_info *iio_lookup_ext_info(
+						const struct iio_channel *chan,
+						const char *attr)
+{
+	const struct iio_chan_spec_ext_info *ext_info;
+
+	if (!chan->channel->ext_info)
+		return NULL;
+
+	for (ext_info = chan->channel->ext_info; ext_info->name; ++ext_info) {
+		if (!strcmp(attr, ext_info->name))
+			return ext_info;
+	}
+
+	return NULL;
+}
+
+ssize_t iio_read_channel_ext_info(struct iio_channel *chan,
+				  const char *attr, char *buf)
+{
+	const struct iio_chan_spec_ext_info *ext_info;
+
+	ext_info = iio_lookup_ext_info(chan, attr);
+	if (!ext_info)
+		return -EINVAL;
+
+	return ext_info->read(chan->indio_dev, ext_info->private,
+			      chan->channel, buf);
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_ext_info);
+
+ssize_t iio_write_channel_ext_info(struct iio_channel *chan, const char *attr,
+				   const char *buf, size_t len)
+{
+	const struct iio_chan_spec_ext_info *ext_info;
+
+	ext_info = iio_lookup_ext_info(chan, attr);
+	if (!ext_info)
+		return -EINVAL;
+
+	return ext_info->write(chan->indio_dev, ext_info->private,
+			       chan->channel, buf, len);
+}
+EXPORT_SYMBOL_GPL(iio_write_channel_ext_info);