// SPDX-License-Identifier: GPL-2.0-only
/* The industrial I/O core in kernel channel mapping
 *
 * Copyright (c) 2011 Jonathan Cameron
 */
#include <linux/cleanup.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/minmax.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/units.h>

#include <linux/iio/iio.h>
#include <linux/iio/iio-opaque.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;
        const struct iio_map *map;
        struct list_head l;
};

static LIST_HEAD(iio_map_list);
static DEFINE_MUTEX(iio_map_list_lock);

static int iio_map_array_unregister_locked(struct iio_dev *indio_dev)
{
        int ret = -ENODEV;
        struct iio_map_internal *mapi, *next;

        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;
                }
        }
        return ret;
}

int iio_map_array_register(struct iio_dev *indio_dev, const struct iio_map *maps)
{
        struct iio_map_internal *mapi;
        int i = 0;
        int ret;

        if (!maps)
                return 0;

        guard(mutex)(&iio_map_list_lock);
        while (maps[i].consumer_dev_name) {
                mapi = kzalloc_obj(*mapi);
                if (!mapi) {
                        ret = -ENOMEM;
                        goto error_ret;
                }
                mapi->map = &maps[i];
                mapi->indio_dev = indio_dev;
                list_add_tail(&mapi->l, &iio_map_list);
                i++;
        }

        return 0;
error_ret:
        iio_map_array_unregister_locked(indio_dev);
        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)
{
        guard(mutex)(&iio_map_list_lock);
        return iio_map_array_unregister_locked(indio_dev);
}
EXPORT_SYMBOL_GPL(iio_map_array_unregister);

static void iio_map_array_unregister_cb(void *indio_dev)
{
        iio_map_array_unregister(indio_dev);
}

int devm_iio_map_array_register(struct device *dev, struct iio_dev *indio_dev,
                                const struct iio_map *maps)
{
        int ret;

        ret = iio_map_array_register(indio_dev, maps);
        if (ret)
                return ret;

        return devm_add_action_or_reset(dev, iio_map_array_unregister_cb, indio_dev);
}
EXPORT_SYMBOL_GPL(devm_iio_map_array_register);

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;
}

/**
 * __fwnode_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 __fwnode_iio_simple_xlate(struct iio_dev *indio_dev,
                                     const struct fwnode_reference_args *iiospec)
{
        if (!iiospec->nargs)
                return 0;

        if (iiospec->args[0] >= indio_dev->num_channels) {
                dev_err(&indio_dev->dev, "invalid channel index %llu\n",
                        iiospec->args[0]);
                return -EINVAL;
        }

        return iiospec->args[0];
}

static int __fwnode_iio_channel_get(struct iio_channel *channel,
                                    struct fwnode_handle *fwnode, int index)
{
        struct fwnode_reference_args iiospec;
        struct device *idev;
        struct iio_dev *indio_dev;
        int err;

        err = fwnode_property_get_reference_args(fwnode, "io-channels",
                                                 "#io-channel-cells", 0,
                                                 index, &iiospec);
        if (err)
                return err;

        idev = bus_find_device_by_fwnode(&iio_bus_type, iiospec.fwnode);
        if (!idev) {
                fwnode_handle_put(iiospec.fwnode);
                return -EPROBE_DEFER;
        }

        indio_dev = dev_to_iio_dev(idev);
        channel->indio_dev = indio_dev;
        if (indio_dev->info->fwnode_xlate)
                index = indio_dev->info->fwnode_xlate(indio_dev, &iiospec);
        else
                index = __fwnode_iio_simple_xlate(indio_dev, &iiospec);
        fwnode_handle_put(iiospec.fwnode);
        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 *fwnode_iio_channel_get(struct fwnode_handle *fwnode,
                                                  int index)
{
        int err;

        if (index < 0)
                return ERR_PTR(-EINVAL);

        struct iio_channel *channel __free(kfree) =
                kzalloc_obj(*channel);
        if (!channel)
                return ERR_PTR(-ENOMEM);

        err = __fwnode_iio_channel_get(channel, fwnode, index);
        if (err)
                return ERR_PTR(err);

        return_ptr(channel);
}

static struct iio_channel *
__fwnode_iio_channel_get_by_name(struct fwnode_handle *fwnode, const char *name)
{
        struct iio_channel *chan;
        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 fwnode_iio_channel_get()
         * will fail.
         */
        if (name)
                index = fwnode_property_match_string(fwnode, "io-channel-names",
                                                     name);

        chan = fwnode_iio_channel_get(fwnode, index);
        if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
                return chan;
        if (name) {
                if (index >= 0) {
                        pr_err("ERROR: could not get IIO channel %pfw:%s(%i)\n",
                               fwnode, name, index);
                        /*
                         * In this case, we found 'name' in 'io-channel-names'
                         * but somehow we still fail so that we should not proceed
                         * with any other lookup. Hence, explicitly return -EINVAL
                         * (maybe not the better error code) so that the caller
                         * won't do a system lookup.
                         */
                        return ERR_PTR(-EINVAL);
                }
                /*
                 * If index < 0, then fwnode_property_get_reference_args() fails
                 * with -EINVAL or -ENOENT (ACPI case) which is expected. We
                 * should not proceed if we get any other error.
                 */
                if (PTR_ERR(chan) != -EINVAL && PTR_ERR(chan) != -ENOENT)
                        return chan;
        } else if (PTR_ERR(chan) != -ENOENT) {
                /*
                 * if !name, then we should only proceed the lookup if
                 * fwnode_property_get_reference_args() returns -ENOENT.
                 */
                return chan;
        }

        /* so we continue the lookup */
        return ERR_PTR(-ENODEV);
}

struct iio_channel *fwnode_iio_channel_get_by_name(struct fwnode_handle *fwnode,
                                                   const char *name)
{
        struct fwnode_handle *parent;
        struct iio_channel *chan;

        /* Walk up the tree of devices looking for a matching iio channel */
        chan = __fwnode_iio_channel_get_by_name(fwnode, name);
        if (!IS_ERR(chan) || PTR_ERR(chan) != -ENODEV)
                return chan;

        /*
         * 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.
         */
        fwnode_for_each_parent_node(fwnode, parent) {
                if (!fwnode_property_present(parent, "io-channel-ranges")) {
                        fwnode_handle_put(parent);
                        return ERR_PTR(-ENODEV);
                }

                chan = __fwnode_iio_channel_get_by_name(parent, name);
                if (!IS_ERR(chan) || PTR_ERR(chan) != -ENODEV) {
                        fwnode_handle_put(parent);
                        return chan;
                }
        }

        return ERR_PTR(-ENODEV);
}
EXPORT_SYMBOL_GPL(fwnode_iio_channel_get_by_name);

static struct iio_channel *fwnode_iio_channel_get_all(struct device *dev)
{
        struct fwnode_handle *fwnode = dev_fwnode(dev);
        int i, mapind, nummaps = 0;
        int ret;

        do {
                ret = fwnode_property_get_reference_args(fwnode, "io-channels",
                                                         "#io-channel-cells", 0,
                                                         nummaps, NULL);
                if (ret < 0)
                        break;
        } while (++nummaps);

        if (nummaps == 0)
                return ERR_PTR(-ENODEV);

        /* NULL terminated array to save passing size */
        struct iio_channel *chans __free(kfree) =
                kzalloc_objs(*chans, nummaps + 1);
        if (!chans)
                return ERR_PTR(-ENOMEM);

        /* Search for FW matches */
        for (mapind = 0; mapind < nummaps; mapind++) {
                ret = __fwnode_iio_channel_get(&chans[mapind], fwnode, mapind);
                if (ret)
                        goto error_free_chans;
        }
        return_ptr(chans);

error_free_chans:
        for (i = 0; i < mapind; i++)
                iio_device_put(chans[i].indio_dev);
        return ERR_PTR(ret);
}

static struct iio_channel *iio_channel_get_sys(const char *name,
                                               const char *channel_name)
{
        struct iio_map_internal *c_i = NULL, *c = NULL;
        int err;

        if (!(name || channel_name))
                return ERR_PTR(-ENODEV);

        /* first find matching entry the channel map */
        scoped_guard(mutex, &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;
                }
        }
        if (!c)
                return ERR_PTR(-ENODEV);

        struct iio_channel *channel __free(kfree) =
                kzalloc(sizeof(*channel), GFP_KERNEL);
        if (!channel) {
                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) {
                        err = -EINVAL;
                        goto error_no_mem;
                }
        }

        return_ptr(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 = fwnode_iio_channel_get_by_name(dev_fwnode(dev),
                                                         channel_name);
                if (!IS_ERR(channel) || PTR_ERR(channel) != -ENODEV)
                        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(void *iio_channel)
{
        iio_channel_release(iio_channel);
}

struct iio_channel *devm_iio_channel_get(struct device *dev,
                                         const char *channel_name)
{
        struct iio_channel *channel;
        int ret;

        channel = iio_channel_get(dev, channel_name);
        if (IS_ERR(channel))
                return channel;

        ret = devm_add_action_or_reset(dev, devm_iio_channel_free, channel);
        if (ret)
                return ERR_PTR(ret);

        return channel;
}
EXPORT_SYMBOL_GPL(devm_iio_channel_get);

struct iio_channel *devm_fwnode_iio_channel_get_by_name(struct device *dev,
                                                        struct fwnode_handle *fwnode,
                                                        const char *channel_name)
{
        struct iio_channel *channel;
        int ret;

        channel = fwnode_iio_channel_get_by_name(fwnode, channel_name);
        if (IS_ERR(channel))
                return channel;

        ret = devm_add_action_or_reset(dev, devm_iio_channel_free, channel);
        if (ret)
                return ERR_PTR(ret);

        return channel;
}
EXPORT_SYMBOL_GPL(devm_fwnode_iio_channel_get_by_name);

struct iio_channel *iio_channel_get_all(struct device *dev)
{
        const char *name;
        struct iio_map_internal *c = NULL;
        struct iio_channel *fw_chans;
        int nummaps = 0;
        int mapind = 0;
        int i, ret;

        if (!dev)
                return ERR_PTR(-EINVAL);

        fw_chans = fwnode_iio_channel_get_all(dev);
        /*
         * We only want to carry on if the error is -ENODEV.  Anything else
         * should be reported up the stack.
         */
        if (!IS_ERR(fw_chans) || PTR_ERR(fw_chans) != -ENODEV)
                return fw_chans;

        name = dev_name(dev);

        guard(mutex)(&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)
                return ERR_PTR(-ENODEV);

        /* NULL terminated array to save passing size */
        struct iio_channel *chans __free(kfree) =
                kzalloc_objs(*chans, nummaps + 1);
        if (!chans)
                return ERR_PTR(-ENOMEM);

        /* 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) {
                        ret = -EINVAL;
                        goto error_free_chans;
                }
                iio_device_get(chans[mapind].indio_dev);
                mapind++;
        }
        if (mapind == 0) {
                ret = -ENODEV;
                goto error_free_chans;
        }

        return_ptr(chans);

error_free_chans:
        for (i = 0; i < mapind; i++)
                iio_device_put(chans[i].indio_dev);
        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(void *iio_channels)
{
        iio_channel_release_all(iio_channels);
}

struct iio_channel *devm_iio_channel_get_all(struct device *dev)
{
        struct iio_channel *channels;
        int ret;

        channels = iio_channel_get_all(dev);
        if (IS_ERR(channels))
                return channels;

        ret = devm_add_action_or_reset(dev, devm_iio_channel_free_all,
                                       channels);
        if (ret)
                return ERR_PTR(ret);

        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)
{
        const struct iio_info *iio_info = chan->indio_dev->info;
        int unused;
        int vals[INDIO_MAX_RAW_ELEMENTS];
        int ret;
        int val_len = 2;

        if (!val2)
                val2 = &unused;

        if (!iio_channel_has_info(chan->channel, info))
                return -EINVAL;

        if (iio_info->read_raw_multi) {
                ret = iio_info->read_raw_multi(chan->indio_dev,
                                               chan->channel,
                                               INDIO_MAX_RAW_ELEMENTS,
                                               vals, &val_len, info);
                *val = vals[0];
                *val2 = vals[1];
        } else if (iio_info->read_raw) {
                ret = iio_info->read_raw(chan->indio_dev,
                                         chan->channel, val, val2, info);
        } else {
                return -EINVAL;
        }

        return ret;
}

int iio_read_channel_raw(struct iio_channel *chan, int *val)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
}
EXPORT_SYMBOL_GPL(iio_read_channel_raw);

int iio_read_channel_average_raw(struct iio_channel *chan, int *val)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_AVERAGE_RAW);
}
EXPORT_SYMBOL_GPL(iio_read_channel_average_raw);

int iio_multiply_value(int *result, s64 multiplier,
                       unsigned int type, int val, int val2)
{
        s64 denominator;

        switch (type) {
        case IIO_VAL_INT:
                *result = multiplier * val;
                return IIO_VAL_INT;
        case IIO_VAL_INT_PLUS_MICRO:
        case IIO_VAL_INT_PLUS_NANO:
                switch (type) {
                case IIO_VAL_INT_PLUS_MICRO:
                        denominator = MICRO;
                        break;
                case IIO_VAL_INT_PLUS_NANO:
                        denominator = NANO;
                        break;
                }
                *result = multiplier * abs(val);
                *result += div_s64(multiplier * abs(val2), denominator);
                if (val < 0 || val2 < 0)
                        *result *= -1;
                return IIO_VAL_INT;
        case IIO_VAL_FRACTIONAL:
                *result = div_s64(multiplier * val, val2);
                return IIO_VAL_INT;
        case IIO_VAL_FRACTIONAL_LOG2:
                *result = (multiplier * val) >> val2;
                return IIO_VAL_INT;
        default:
                return -EINVAL;
        }
}
EXPORT_SYMBOL_NS_GPL(iio_multiply_value, "IIO_UNIT_TEST");

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;
        int ret;

        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 = raw64 * scale;
                return 0;
        }

        ret = iio_multiply_value(processed, raw64 * scale,
                                 scale_type, scale_val, scale_val2);
        if (ret < 0)
                return ret;

        return 0;
}

int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
                                 int *processed, unsigned int scale)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_convert_raw_to_processed_unlocked(chan, raw, processed,
                                                     scale);
}
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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_read(chan, val, val2, attribute);
}
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_scale(struct iio_channel *chan, int *val,
                                     unsigned int scale)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
        int ret, pval, pval2;

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
                ret = iio_channel_read(chan, &pval, &pval2,
                                       IIO_CHAN_INFO_PROCESSED);
                if (ret < 0)
                        return ret;

                return iio_multiply_value(val, scale, ret, pval, pval2);
        } else {
                ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
                if (ret < 0)
                        return ret;

                return iio_convert_raw_to_processed_unlocked(chan, *val, val,
                                                             scale);
        }
}
EXPORT_SYMBOL_GPL(iio_read_channel_processed_scale);

int iio_read_channel_processed(struct iio_channel *chan, int *val)
{
        /* This is just a special case with scale factor 1 */
        return iio_read_channel_processed_scale(chan, val, 1);
}
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)
{
        const struct iio_info *iio_info = chan->indio_dev->info;

        if (!iio_channel_has_available(chan->channel, info))
                return -EINVAL;

        if (iio_info->read_avail)
                return iio_info->read_avail(chan->indio_dev, chan->channel,
                                            vals, type, length, info);
        return -EINVAL;
}

int iio_read_avail_channel_attribute(struct iio_channel *chan,
                                     const int **vals, int *type, int *length,
                                     enum iio_chan_info_enum attribute)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_read_avail(chan, vals, type, length, attribute);
}
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)
{
        const int *vals;
        int length;
        int ret;

        ret = iio_channel_read_avail(chan, &vals, type, &length, info);
        if (ret < 0)
                return ret;

        switch (ret) {
        case IIO_AVAIL_RANGE:
                switch (*type) {
                case IIO_VAL_INT:
                        *val = vals[2];
                        break;
                default:
                        *val = vals[4];
                        if (val2)
                                *val2 = vals[5];
                }
                return 0;

        case IIO_AVAIL_LIST:
                if (length <= 0)
                        return -EINVAL;
                switch (*type) {
                case IIO_VAL_INT:
                        *val = max_array(vals, length);
                        break;
                default:
                        /* TODO: learn about max for other iio values */
                        return -EINVAL;
                }
                return 0;

        default:
                return -EINVAL;
        }
}

int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
        int type;

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_read_max(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
}
EXPORT_SYMBOL_GPL(iio_read_max_channel_raw);

static int iio_channel_read_min(struct iio_channel *chan,
                                int *val, int *val2, int *type,
                                enum iio_chan_info_enum info)
{
        const int *vals;
        int length;
        int ret;

        ret = iio_channel_read_avail(chan, &vals, type, &length, info);
        if (ret < 0)
                return ret;

        switch (ret) {
        case IIO_AVAIL_RANGE:
                switch (*type) {
                case IIO_VAL_INT:
                        *val = vals[0];
                        break;
                default:
                        *val = vals[0];
                        if (val2)
                                *val2 = vals[1];
                }
                return 0;

        case IIO_AVAIL_LIST:
                if (length <= 0)
                        return -EINVAL;
                switch (*type) {
                case IIO_VAL_INT:
                        *val = min_array(vals, length);
                        break;
                default:
                        /* TODO: learn about min for other iio values */
                        return -EINVAL;
                }
                return 0;

        default:
                return -EINVAL;
        }
}

int iio_read_min_channel_raw(struct iio_channel *chan, int *val)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);
        int type;

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_read_min(chan, val, NULL, &type, IIO_CHAN_INFO_RAW);
}
EXPORT_SYMBOL_GPL(iio_read_min_channel_raw);

int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        *type = chan->channel->type;

        return 0;
}
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)
{
        const struct iio_info *iio_info = chan->indio_dev->info;

        if (iio_info->write_raw)
                return iio_info->write_raw(chan->indio_dev,
                                           chan->channel, val, val2, info);
        return -EINVAL;
}

int iio_write_channel_attribute(struct iio_channel *chan, int val, int val2,
                                enum iio_chan_info_enum attribute)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(chan->indio_dev);

        guard(mutex)(&iio_dev_opaque->info_exist_lock);
        if (!chan->indio_dev->info)
                return -ENODEV;

        return iio_channel_write(chan, val, val2, attribute);
}
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;

        if (!buf || offset_in_page(buf)) {
                pr_err("iio: invalid ext_info read buffer\n");
                return -EINVAL;
        }

        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);

ssize_t iio_read_channel_label(struct iio_channel *chan, char *buf)
{
        if (!buf || offset_in_page(buf)) {
                pr_err("iio: invalid label read buffer\n");
                return -EINVAL;
        }

        return do_iio_read_channel_label(chan->indio_dev, chan->channel, buf);
}
EXPORT_SYMBOL_GPL(iio_read_channel_label);