// SPDX-License-Identifier: GPL-2.0-only
/* Hwmon client for industrial I/O devices
 *
 * Copyright (c) 2011 Jonathan Cameron
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/property.h>

#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/iio/consumer.h>
#include <linux/iio/types.h>

/**
 * struct iio_hwmon_state - device instance state
 * @channels:           filled with array of channels from iio
 * @num_channels:       number of channels in channels (saves counting twice)
 * @attr_group:         the group of attributes
 * @groups:             null terminated array of attribute groups
 * @attrs:              null terminated array of attribute pointers.
 */
struct iio_hwmon_state {
        struct iio_channel *channels;
        int num_channels;
        struct attribute_group attr_group;
        const struct attribute_group *groups[2];
        struct attribute **attrs;
};

static ssize_t iio_hwmon_read_label(struct device *dev,
                                  struct device_attribute *attr,
                                  char *buf)
{
        struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
        struct iio_hwmon_state *state = dev_get_drvdata(dev);
        struct iio_channel *chan = &state->channels[sattr->index];

        return iio_read_channel_label(chan, buf);
}

/*
 * Assumes that IIO and hwmon operate in the same base units.
 * This is supposed to be true, but needs verification for
 * new channel types.
 */
static ssize_t iio_hwmon_read_val(struct device *dev,
                                  struct device_attribute *attr,
                                  char *buf)
{
        int result;
        int ret;
        struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
        struct iio_hwmon_state *state = dev_get_drvdata(dev);
        struct iio_channel *chan = &state->channels[sattr->index];
        enum iio_chan_type type;

        ret = iio_get_channel_type(chan, &type);
        if (ret < 0)
                return ret;

        if (type == IIO_POWER)
                /* mili-Watts to micro-Watts conversion */
                ret = iio_read_channel_processed_scale(chan, &result, 1000);
        else
                ret = iio_read_channel_processed(chan, &result);
        if (ret < 0)
                return ret;

        return sprintf(buf, "%d\n", result);
}

static int iio_hwmon_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct iio_hwmon_state *st;
        struct sensor_device_attribute *a;
        int ret, i, attr = 0;
        int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
        enum iio_chan_type type;
        struct iio_channel *channels;
        struct device *hwmon_dev;
        char *sname;
        void *buf;

        channels = devm_iio_channel_get_all(dev);
        if (IS_ERR(channels)) {
                ret = PTR_ERR(channels);
                if (ret == -ENODEV)
                        ret = -EPROBE_DEFER;
                return dev_err_probe(dev, ret,
                                     "Failed to get channels\n");
        }

        st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
        buf = (void *)devm_get_free_pages(dev, GFP_KERNEL, 0);
        if (!st || !buf)
                return -ENOMEM;

        st->channels = channels;

        /* count how many channels we have */
        while (st->channels[st->num_channels].indio_dev)
                st->num_channels++;

        st->attrs = devm_kcalloc(dev,
                                 2 * st->num_channels + 1, sizeof(*st->attrs),
                                 GFP_KERNEL);
        if (st->attrs == NULL)
                return -ENOMEM;

        for (i = 0; i < st->num_channels; i++) {
                const char *prefix;
                int n;

                a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
                if (a == NULL)
                        return -ENOMEM;

                sysfs_attr_init(&a->dev_attr.attr);
                ret = iio_get_channel_type(&st->channels[i], &type);
                if (ret < 0)
                        return ret;

                switch (type) {
                case IIO_VOLTAGE:
                        n = in_i++;
                        prefix = "in";
                        break;
                case IIO_TEMP:
                        n = temp_i++;
                        prefix = "temp";
                        break;
                case IIO_CURRENT:
                        n = curr_i++;
                        prefix = "curr";
                        break;
                case IIO_POWER:
                        n = power_i++;
                        prefix = "power";
                        break;
                case IIO_HUMIDITYRELATIVE:
                        n = humidity_i++;
                        prefix = "humidity";
                        break;
                default:
                        return -EINVAL;
                }

                a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
                                                       "%s%d_input",
                                                       prefix, n);
                if (a->dev_attr.attr.name == NULL)
                        return -ENOMEM;

                a->dev_attr.show = iio_hwmon_read_val;
                a->dev_attr.attr.mode = 0444;
                a->index = i;
                st->attrs[attr++] = &a->dev_attr.attr;

                /* Let's see if we have a label... */
                if (iio_read_channel_label(&st->channels[i], buf) < 0)
                        continue;

                a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
                if (a == NULL)
                        return -ENOMEM;

                sysfs_attr_init(&a->dev_attr.attr);
                a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
                                                       "%s%d_label",
                                                       prefix, n);
                if (!a->dev_attr.attr.name)
                        return -ENOMEM;

                a->dev_attr.show = iio_hwmon_read_label;
                a->dev_attr.attr.mode = 0444;
                a->index = i;
                st->attrs[attr++] = &a->dev_attr.attr;
        }

        devm_free_pages(dev, (unsigned long)buf);

        st->attr_group.attrs = st->attrs;
        st->groups[0] = &st->attr_group;

        if (dev_fwnode(dev)) {
                sname = devm_kasprintf(dev, GFP_KERNEL, "%pfwP", dev_fwnode(dev));
                if (!sname)
                        return -ENOMEM;
                strreplace(sname, '-', '_');
        } else {
                sname = "iio_hwmon";
        }

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, sname, st,
                                                           st->groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct of_device_id iio_hwmon_of_match[] = {
        { .compatible = "iio-hwmon", },
        { }
};
MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);

static struct platform_driver iio_hwmon_driver = {
        .driver = {
                .name = "iio_hwmon",
                .of_match_table = iio_hwmon_of_match,
        },
        .probe = iio_hwmon_probe,
};

module_platform_driver(iio_hwmon_driver);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("IIO to hwmon driver");
MODULE_LICENSE("GPL v2");