drivers/hwmon/iio_hwmon.c

   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  * @groups:             null terminated array of attribute groups
  28  * @attrs:              null terminated array of attribute pointers.
  29  */
  30 struct iio_hwmon_state {
  31         struct iio_channel *channels;
  32         int num_channels;
  33         struct device *hwmon_dev;
  34         struct attribute_group attr_group;
  35         const struct attribute_group *groups[2];
  36         struct attribute **attrs;
  37 };
  38
  39 /*
  40  * Assumes that IIO and hwmon operate in the same base units.
  41  * This is supposed to be true, but needs verification for
  42  * new channel types.
  43  */
  44 static ssize_t iio_hwmon_read_val(struct device *dev,
  45                                   struct device_attribute *attr,
  46                                   char *buf)
  47 {
  48         int result;
  49         int ret;
  50         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  51         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  52
  53         ret = iio_read_channel_processed(&state->channels[sattr->index],
  54                                         &result);
  55         if (ret < 0)
  56                 return ret;
  57
  58         return sprintf(buf, "%d\n", result);
  59 }
  60
  61 static int iio_hwmon_probe(struct platform_device *pdev)
  62 {
  63         struct device *dev = &pdev->dev;
  64         struct iio_hwmon_state *st;
  65         struct sensor_device_attribute *a;
  66         int ret, i;
  67         int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1;
  68         enum iio_chan_type type;
  69         struct iio_channel *channels;
  70         const char *name = "iio_hwmon";
  71         char *sname;
  72
  73         if (dev->of_node && dev->of_node->name)
  74                 name = dev->of_node->name;
  75
  76         channels = 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                 ret = -ENOMEM;
  86                 goto error_release_channels;
  87         }
  88
  89         st->channels = channels;
  90
  91         /* count how many attributes we have */
  92         while (st->channels[st->num_channels].indio_dev)
  93                 st->num_channels++;
  94
  95         st->attrs = devm_kcalloc(dev,
  96                                  st->num_channels + 1, sizeof(*st->attrs),
  97                                  GFP_KERNEL);
  98         if (st->attrs == NULL) {
  99                 ret = -ENOMEM;
 100                 goto error_release_channels;
 101         }
 102
 103         for (i = 0; i < st->num_channels; i++) {
 104                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 105                 if (a == NULL) {
 106                         ret = -ENOMEM;
 107                         goto error_release_channels;
 108                 }
 109
 110                 sysfs_attr_init(&a->dev_attr.attr);
 111                 ret = iio_get_channel_type(&st->channels[i], &type);
 112                 if (ret < 0)
 113                         goto error_release_channels;
 114
 115                 switch (type) {
 116                 case IIO_VOLTAGE:
 117                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 118                                                                "in%d_input",
 119                                                                in_i++);
 120                         break;
 121                 case IIO_TEMP:
 122                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 123                                                                "temp%d_input",
 124                                                                temp_i++);
 125                         break;
 126                 case IIO_CURRENT:
 127                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 128                                                                "curr%d_input",
 129                                                                curr_i++);
 130                         break;
 131                 case IIO_HUMIDITYRELATIVE:
 132                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 133                                                                "humidity%d_input",
 134                                                                humidity_i++);
 135                         break;
 136                 default:
 137                         ret = -EINVAL;
 138                         goto error_release_channels;
 139                 }
 140                 if (a->dev_attr.attr.name == NULL) {
 141                         ret = -ENOMEM;
 142                         goto error_release_channels;
 143                 }
 144                 a->dev_attr.show = iio_hwmon_read_val;
 145                 a->dev_attr.attr.mode = S_IRUGO;
 146                 a->index = i;
 147                 st->attrs[i] = &a->dev_attr.attr;
 148         }
 149
 150         st->attr_group.attrs = st->attrs;
 151         st->groups[0] = &st->attr_group;
 152
 153         sname = devm_kstrdup(dev, name, GFP_KERNEL);
 154         if (!sname) {
 155                 ret = -ENOMEM;
 156                 goto error_release_channels;
 157         }
 158
 159         strreplace(sname, '-', '_');
 160         st->hwmon_dev = hwmon_device_register_with_groups(dev, sname, st,
 161                                                           st->groups);
 162         if (IS_ERR(st->hwmon_dev)) {
 163                 ret = PTR_ERR(st->hwmon_dev);
 164                 goto error_release_channels;
 165         }
 166         platform_set_drvdata(pdev, st);
 167         return 0;
 168
 169 error_release_channels:
 170         iio_channel_release_all(channels);
 171         return ret;
 172 }
 173
 174 static int iio_hwmon_remove(struct platform_device *pdev)
 175 {
 176         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 177
 178         hwmon_device_unregister(st->hwmon_dev);
 179         iio_channel_release_all(st->channels);
 180
 181         return 0;
 182 }
 183
 184 static const struct of_device_id iio_hwmon_of_match[] = {
 185         { .compatible = "iio-hwmon", },
 186         { }
 187 };
 188 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
 189
 190 static struct platform_driver __refdata iio_hwmon_driver = {
 191         .driver = {
 192                 .name = "iio_hwmon",
 193                 .of_match_table = iio_hwmon_of_match,
 194         },
 195         .probe = iio_hwmon_probe,
 196         .remove = iio_hwmon_remove,
 197 };
 198
 199 module_platform_driver(iio_hwmon_driver);
 200
 201 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 202 MODULE_DESCRIPTION("IIO to hwmon driver");
 203 MODULE_LICENSE("GPL v2");