linux/drivers/hwmon/iio_hwmon.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/* Hwmon client for industrial I/O devices
   3 *
   4 * Copyright (c) 2011 Jonathan Cameron
   5 */
   6
   7#include <linux/kernel.h>
   8#include <linux/slab.h>
   9#include <linux/module.h>
  10#include <linux/err.h>
  11#include <linux/platform_device.h>
  12#include <linux/hwmon.h>
  13#include <linux/of.h>
  14#include <linux/hwmon-sysfs.h>
  15#include <linux/iio/consumer.h>
  16#include <linux/iio/types.h>
  17
  18/**
  19 * struct iio_hwmon_state - device instance state
  20 * @channels:           filled with array of channels from iio
  21 * @num_channels:       number of channels in channels (saves counting twice)
  22 * @attr_group:         the group of attributes
  23 * @groups:             null terminated array of attribute groups
  24 * @attrs:              null terminated array of attribute pointers.
  25 */
  26struct iio_hwmon_state {
  27        struct iio_channel *channels;
  28        int num_channels;
  29        struct attribute_group attr_group;
  30        const struct attribute_group *groups[2];
  31        struct attribute **attrs;
  32};
  33
  34/*
  35 * Assumes that IIO and hwmon operate in the same base units.
  36 * This is supposed to be true, but needs verification for
  37 * new channel types.
  38 */
  39static ssize_t iio_hwmon_read_val(struct device *dev,
  40                                  struct device_attribute *attr,
  41                                  char *buf)
  42{
  43        int result;
  44        int ret;
  45        struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  46        struct iio_hwmon_state *state = dev_get_drvdata(dev);
  47        struct iio_channel *chan = &state->channels[sattr->index];
  48        enum iio_chan_type type;
  49
  50        ret = iio_read_channel_processed(chan, &result);
  51        if (ret < 0)
  52                return ret;
  53
  54        ret = iio_get_channel_type(chan, &type);
  55        if (ret < 0)
  56                return ret;
  57
  58        if (type == IIO_POWER)
  59                result *= 1000; /* mili-Watts to micro-Watts conversion */
  60
  61        return sprintf(buf, "%d\n", result);
  62}
  63
  64static int iio_hwmon_probe(struct platform_device *pdev)
  65{
  66        struct device *dev = &pdev->dev;
  67        struct iio_hwmon_state *st;
  68        struct sensor_device_attribute *a;
  69        int ret, i;
  70        int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
  71        enum iio_chan_type type;
  72        struct iio_channel *channels;
  73        struct device *hwmon_dev;
  74        char *sname;
  75
  76        channels = devm_iio_channel_get_all(dev);
  77        if (IS_ERR(channels)) {
  78                if (PTR_ERR(channels) == -ENODEV)
  79                        return -EPROBE_DEFER;
  80                return PTR_ERR(channels);
  81        }
  82
  83        st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  84        if (st == NULL)
  85                return -ENOMEM;
  86
  87        st->channels = channels;
  88
  89        /* count how many attributes we have */
  90        while (st->channels[st->num_channels].indio_dev)
  91                st->num_channels++;
  92
  93        st->attrs = devm_kcalloc(dev,
  94                                 st->num_channels + 1, sizeof(*st->attrs),
  95                                 GFP_KERNEL);
  96        if (st->attrs == NULL)
  97                return -ENOMEM;
  98
  99        for (i = 0; i < st->num_channels; i++) {
 100                const char *prefix;
 101                int n;
 102
 103                a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 104                if (a == NULL)
 105                        return -ENOMEM;
 106
 107                sysfs_attr_init(&a->dev_attr.attr);
 108                ret = iio_get_channel_type(&st->channels[i], &type);
 109                if (ret < 0)
 110                        return ret;
 111
 112                switch (type) {
 113                case IIO_VOLTAGE:
 114                        n = in_i++;
 115                        prefix = "in";
 116                        break;
 117                case IIO_TEMP:
 118                        n = temp_i++;
 119                        prefix = "temp";
 120                        break;
 121                case IIO_CURRENT:
 122                        n = curr_i++;
 123                        prefix = "curr";
 124                        break;
 125                case IIO_POWER:
 126                        n = power_i++;
 127                        prefix = "power";
 128                        break;
 129                case IIO_HUMIDITYRELATIVE:
 130                        n = humidity_i++;
 131                        prefix = "humidity";
 132                        break;
 133                default:
 134                        return -EINVAL;
 135                }
 136
 137                a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 138                                                       "%s%d_input",
 139                                                       prefix, n);
 140                if (a->dev_attr.attr.name == NULL)
 141                        return -ENOMEM;
 142
 143                a->dev_attr.show = iio_hwmon_read_val;
 144                a->dev_attr.attr.mode = 0444;
 145                a->index = i;
 146                st->attrs[i] = &a->dev_attr.attr;
 147        }
 148
 149        st->attr_group.attrs = st->attrs;
 150        st->groups[0] = &st->attr_group;
 151
 152        if (dev->of_node) {
 153                sname = devm_kasprintf(dev, GFP_KERNEL, "%pOFn", dev->of_node);
 154                if (!sname)
 155                        return -ENOMEM;
 156                strreplace(sname, '-', '_');
 157        } else {
 158                sname = "iio_hwmon";
 159        }
 160
 161        hwmon_dev = devm_hwmon_device_register_with_groups(dev, sname, st,
 162                                                           st->groups);
 163        return PTR_ERR_OR_ZERO(hwmon_dev);
 164}
 165
 166static const struct of_device_id iio_hwmon_of_match[] = {
 167        { .compatible = "iio-hwmon", },
 168        { }
 169};
 170MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
 171
 172static struct platform_driver __refdata iio_hwmon_driver = {
 173        .driver = {
 174                .name = "iio_hwmon",
 175                .of_match_table = iio_hwmon_of_match,
 176        },
 177        .probe = iio_hwmon_probe,
 178};
 179
 180module_platform_driver(iio_hwmon_driver);
 181
 182MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 183MODULE_DESCRIPTION("IIO to hwmon driver");
 184MODULE_LICENSE("GPL v2");
 185