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  * @attrs:              null terminated array of attribute pointers.
  28  */
  29 struct iio_hwmon_state {
  30         struct iio_channel *channels;
  31         int num_channels;
  32         struct device *hwmon_dev;
  33         struct attribute_group attr_group;
  34         const struct attribute_group *groups[2];
  35         struct attribute **attrs;
  36 };
  37
  38 /*
  39  * Assumes that IIO and hwmon operate in the same base units.
  40  * This is supposed to be true, but needs verification for
  41  * new channel types.
  42  */
  43 static ssize_t iio_hwmon_read_val(struct device *dev,
  44                                   struct device_attribute *attr,
  45                                   char *buf)
  46 {
  47         int result;
  48         int ret;
  49         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  50         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  51
  52         ret = iio_read_channel_processed(&state->channels[sattr->index],
  53                                         &result);
  54         if (ret < 0)
  55                 return ret;
  56
  57         return sprintf(buf, "%d\n", result);
  58 }
  59
  60 static int iio_hwmon_probe(struct platform_device *pdev)
  61 {
  62         struct device *dev = &pdev->dev;
  63         struct iio_hwmon_state *st;
  64         struct sensor_device_attribute *a;
  65         int ret, i;
  66         int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1;
  67         enum iio_chan_type type;
  68         struct iio_channel *channels;
  69         const char *name = "iio_hwmon";
  70         char *sname;
  71
  72         if (dev->of_node && dev->of_node->name)
  73                 name = dev->of_node->name;
  74
  75         channels = iio_channel_get_all(dev);
  76         if (IS_ERR(channels))
  77                 return PTR_ERR(channels);
  78
  79         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  80         if (st == NULL) {
  81                 ret = -ENOMEM;
  82                 goto error_release_channels;
  83         }
  84
  85         st->channels = channels;
  86
  87         /* count how many attributes we have */
  88         while (st->channels[st->num_channels].indio_dev)
  89                 st->num_channels++;
  90
  91         st->attrs = devm_kzalloc(dev,
  92                                  sizeof(*st->attrs) * (st->num_channels + 1),
  93                                  GFP_KERNEL);
  94         if (st->attrs == NULL) {
  95                 ret = -ENOMEM;
  96                 goto error_release_channels;
  97         }
  98
  99         for (i = 0; i < st->num_channels; i++) {
 100                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 101                 if (a == NULL) {
 102                         ret = -ENOMEM;
 103                         goto error_release_channels;
 104                 }
 105
 106                 sysfs_attr_init(&a->dev_attr.attr);
 107                 ret = iio_get_channel_type(&st->channels[i], &type);
 108                 if (ret < 0)
 109                         goto error_release_channels;
 110
 111                 switch (type) {
 112                 case IIO_VOLTAGE:
 113                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 114                                                                "in%d_input",
 115                                                                in_i++);
 116                         break;
 117                 case IIO_TEMP:
 118                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 119                                                                "temp%d_input",
 120                                                                temp_i++);
 121                         break;
 122                 case IIO_CURRENT:
 123                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 124                                                                "curr%d_input",
 125                                                                curr_i++);
 126                         break;
 127                 case IIO_HUMIDITYRELATIVE:
 128                         a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 129                                                                "humidity%d_input",
 130                                                                humidity_i++);
 131                         break;
 132                 default:
 133                         ret = -EINVAL;
 134                         goto error_release_channels;
 135                 }
 136                 if (a->dev_attr.attr.name == NULL) {
 137                         ret = -ENOMEM;
 138                         goto error_release_channels;
 139                 }
 140                 a->dev_attr.show = iio_hwmon_read_val;
 141                 a->dev_attr.attr.mode = S_IRUGO;
 142                 a->index = i;
 143                 st->attrs[i] = &a->dev_attr.attr;
 144         }
 145
 146         st->attr_group.attrs = st->attrs;
 147         st->groups[0] = &st->attr_group;
 148
 149         sname = devm_kstrdup(dev, name, GFP_KERNEL);
 150         if (!sname) {
 151                 ret = -ENOMEM;
 152                 goto error_release_channels;
 153         }
 154
 155         strreplace(sname, '-', '_');
 156         st->hwmon_dev = hwmon_device_register_with_groups(dev, sname, st,
 157                                                           st->groups);
 158         if (IS_ERR(st->hwmon_dev)) {
 159                 ret = PTR_ERR(st->hwmon_dev);
 160                 goto error_release_channels;
 161         }
 162         platform_set_drvdata(pdev, st);
 163         return 0;
 164
 165 error_release_channels:
 166         iio_channel_release_all(channels);
 167         return ret;
 168 }
 169
 170 static int iio_hwmon_remove(struct platform_device *pdev)
 171 {
 172         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 173
 174         hwmon_device_unregister(st->hwmon_dev);
 175         iio_channel_release_all(st->channels);
 176
 177         return 0;
 178 }
 179
 180 static const struct of_device_id iio_hwmon_of_match[] = {
 181         { .compatible = "iio-hwmon", },
 182         { }
 183 };
 184 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
 185
 186 static struct platform_driver __refdata iio_hwmon_driver = {
 187         .driver = {
 188                 .name = "iio_hwmon",
 189                 .of_match_table = iio_hwmon_of_match,
 190         },
 191         .probe = iio_hwmon_probe,
 192         .remove = iio_hwmon_remove,
 193 };
 194
 195 module_platform_driver(iio_hwmon_driver);
 196
 197 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 198 MODULE_DESCRIPTION("IIO to hwmon driver");
 199 MODULE_LICENSE("GPL v2");