// SPDX-License-Identifier: GPL-2.0-only
/*
 * Helpers for parsing common ADC information from a firmware node.
 *
 * Copyright (c) 2025 Matti Vaittinen <mazziesaccount@gmail.com>
 */

#include <linux/device.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/types.h>

#include <linux/iio/adc-helpers.h>
#include <linux/iio/iio.h>

/**
 * devm_iio_adc_device_alloc_chaninfo_se - allocate and fill iio_chan_spec for ADC
 *
 * Scan the device node for single-ended ADC channel information. Channel ID is
 * expected to be found from the "reg" property. Allocate and populate the
 * iio_chan_spec structure corresponding to channels that are found. The memory
 * for iio_chan_spec structure will be freed upon device detach.
 *
 * @dev:                Pointer to the ADC device.
 * @template:           Template iio_chan_spec from which the fields of all
 *                      found and allocated channels are initialized.
 * @max_chan_id:        Maximum value of a channel ID. Use negative value if no
 *                      checking is required.
 * @cs:                 Location where pointer to allocated iio_chan_spec
 *                      should be stored.
 *
 * Return:      Number of found channels on success. Negative value to indicate
 *              failure. Specifically, -ENOENT if no channel nodes were found.
 */
int devm_iio_adc_device_alloc_chaninfo_se(struct device *dev,
                                          const struct iio_chan_spec *template,
                                          int max_chan_id,
                                          struct iio_chan_spec **cs)
{
        struct iio_chan_spec *chan_array, *chan;
        int num_chan, ret;

        num_chan = iio_adc_device_num_channels(dev);
        if (num_chan < 0)
                return num_chan;

        if (!num_chan)
                return -ENOENT;

        chan_array = devm_kcalloc(dev, num_chan, sizeof(*chan_array),
                                  GFP_KERNEL);
        if (!chan_array)
                return -ENOMEM;

        chan = &chan_array[0];

        device_for_each_named_child_node_scoped(dev, child, "channel") {
                u32 ch;

                ret = fwnode_property_read_u32(child, "reg", &ch);
                if (ret)
                        return ret;

                if (max_chan_id >= 0 && ch > max_chan_id)
                        return -ERANGE;

                *chan = *template;
                chan->channel = ch;
                chan++;
        }

        *cs = chan_array;

        return num_chan;
}
EXPORT_SYMBOL_NS_GPL(devm_iio_adc_device_alloc_chaninfo_se, "IIO_DRIVER");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
MODULE_DESCRIPTION("IIO ADC fwnode parsing helpers");