linux/drivers/hwmon/iio_hwmon.c
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   1/* Hwmon client for industrial I/O devices
   2 *
   3 * Copyright (c) 2011 Jonathan Cameron
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms of the GNU General Public License version 2 as published by
   7 * the Free Software Foundation.
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/slab.h>
  12#include <linux/module.h>
  13#include <linux/err.h>
  14#include <linux/platform_device.h>
  15#include <linux/hwmon.h>
  16#include <linux/of.h>
  17#include <linux/hwmon-sysfs.h>
  18#include <linux/iio/consumer.h>
  19#include <linux/iio/types.h>
  20
  21/**
  22 * struct iio_hwmon_state - device instance state
  23 * @channels:           filled with array of channels from iio
  24 * @num_channels:       number of channels in channels (saves counting twice)
  25 * @hwmon_dev:          associated hwmon device
  26 * @attr_group: the group of attributes
  27 * @attrs:              null terminated array of attribute pointers.
  28 */
  29struct iio_hwmon_state {
  30        struct iio_channel *channels;
  31        int num_channels;
  32        struct device *hwmon_dev;
  33        struct attribute_group attr_group;
  34        struct attribute **attrs;
  35};
  36
  37/*
  38 * Assumes that IIO and hwmon operate in the same base units.
  39 * This is supposed to be true, but needs verification for
  40 * new channel types.
  41 */
  42static ssize_t iio_hwmon_read_val(struct device *dev,
  43                                  struct device_attribute *attr,
  44                                  char *buf)
  45{
  46        int result;
  47        int ret;
  48        struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  49        struct iio_hwmon_state *state = dev_get_drvdata(dev);
  50
  51        ret = iio_read_channel_processed(&state->channels[sattr->index],
  52                                        &result);
  53        if (ret < 0)
  54                return ret;
  55
  56        return sprintf(buf, "%d\n", result);
  57}
  58
  59static ssize_t show_name(struct device *dev, struct device_attribute *attr,
  60                         char *buf)
  61{
  62        const char *name = "iio_hwmon";
  63
  64        if (dev->of_node && dev->of_node->name)
  65                name = dev->of_node->name;
  66
  67        return sprintf(buf, "%s\n", name);
  68}
  69
  70static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
  71
  72static int iio_hwmon_probe(struct platform_device *pdev)
  73{
  74        struct device *dev = &pdev->dev;
  75        struct iio_hwmon_state *st;
  76        struct sensor_device_attribute *a;
  77        int ret, i;
  78        int in_i = 1, temp_i = 1, curr_i = 1;
  79        enum iio_chan_type type;
  80        struct iio_channel *channels;
  81
  82        channels = iio_channel_get_all(dev);
  83        if (IS_ERR(channels))
  84                return PTR_ERR(channels);
  85
  86        st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  87        if (st == NULL) {
  88                ret = -ENOMEM;
  89                goto error_release_channels;
  90        }
  91
  92        st->channels = channels;
  93
  94        /* count how many attributes we have */
  95        while (st->channels[st->num_channels].indio_dev)
  96                st->num_channels++;
  97
  98        st->attrs = devm_kzalloc(dev,
  99                                 sizeof(*st->attrs) * (st->num_channels + 2),
 100                                 GFP_KERNEL);
 101        if (st->attrs == NULL) {
 102                ret = -ENOMEM;
 103                goto error_release_channels;
 104        }
 105
 106        for (i = 0; i < st->num_channels; i++) {
 107                a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 108                if (a == NULL) {
 109                        ret = -ENOMEM;
 110                        goto error_release_channels;
 111                }
 112
 113                sysfs_attr_init(&a->dev_attr.attr);
 114                ret = iio_get_channel_type(&st->channels[i], &type);
 115                if (ret < 0)
 116                        goto error_release_channels;
 117
 118                switch (type) {
 119                case IIO_VOLTAGE:
 120                        a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 121                                                          "in%d_input",
 122                                                          in_i++);
 123                        break;
 124                case IIO_TEMP:
 125                        a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 126                                                          "temp%d_input",
 127                                                          temp_i++);
 128                        break;
 129                case IIO_CURRENT:
 130                        a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 131                                                          "curr%d_input",
 132                                                          curr_i++);
 133                        break;
 134                default:
 135                        ret = -EINVAL;
 136                        goto error_release_channels;
 137                }
 138                if (a->dev_attr.attr.name == NULL) {
 139                        ret = -ENOMEM;
 140                        goto error_release_channels;
 141                }
 142                a->dev_attr.show = iio_hwmon_read_val;
 143                a->dev_attr.attr.mode = S_IRUGO;
 144                a->index = i;
 145                st->attrs[i] = &a->dev_attr.attr;
 146        }
 147        st->attrs[st->num_channels] = &dev_attr_name.attr;
 148        st->attr_group.attrs = st->attrs;
 149        platform_set_drvdata(pdev, st);
 150        ret = sysfs_create_group(&dev->kobj, &st->attr_group);
 151        if (ret < 0)
 152                goto error_release_channels;
 153
 154        st->hwmon_dev = hwmon_device_register(dev);
 155        if (IS_ERR(st->hwmon_dev)) {
 156                ret = PTR_ERR(st->hwmon_dev);
 157                goto error_remove_group;
 158        }
 159        return 0;
 160
 161error_remove_group:
 162        sysfs_remove_group(&dev->kobj, &st->attr_group);
 163error_release_channels:
 164        iio_channel_release_all(channels);
 165        return ret;
 166}
 167
 168static int iio_hwmon_remove(struct platform_device *pdev)
 169{
 170        struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 171
 172        hwmon_device_unregister(st->hwmon_dev);
 173        sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
 174        iio_channel_release_all(st->channels);
 175
 176        return 0;
 177}
 178
 179static struct of_device_id iio_hwmon_of_match[] = {
 180        { .compatible = "iio-hwmon", },
 181        { }
 182};
 183
 184static struct platform_driver __refdata iio_hwmon_driver = {
 185        .driver = {
 186                .name = "iio_hwmon",
 187                .owner = THIS_MODULE,
 188                .of_match_table = iio_hwmon_of_match,
 189        },
 190        .probe = iio_hwmon_probe,
 191        .remove = iio_hwmon_remove,
 192};
 193
 194module_platform_driver(iio_hwmon_driver);
 195
 196MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 197MODULE_DESCRIPTION("IIO to hwmon driver");
 198MODULE_LICENSE("GPL v2");
 199
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