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;
  67         enum iio_chan_type type;
  68         struct iio_channel *channels;
  69         const char *name = "iio_hwmon";
  70
  71         if (dev->of_node && dev->of_node->name)
  72                 name = dev->of_node->name;
  73
  74         channels = iio_channel_get_all(dev);
  75         if (IS_ERR(channels))
  76                 return PTR_ERR(channels);
  77
  78         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  79         if (st == NULL) {
  80                 ret = -ENOMEM;
  81                 goto error_release_channels;
  82         }
  83
  84         st->channels = channels;
  85
  86         /* count how many attributes we have */
  87         while (st->channels[st->num_channels].indio_dev)
  88                 st->num_channels++;
  89
  90         st->attrs = devm_kzalloc(dev,
  91                                  sizeof(*st->attrs) * (st->num_channels + 1),
  92                                  GFP_KERNEL);
  93         if (st->attrs == NULL) {
  94                 ret = -ENOMEM;
  95                 goto error_release_channels;
  96         }
  97
  98         for (i = 0; i < st->num_channels; i++) {
  99                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 100                 if (a == NULL) {
 101                         ret = -ENOMEM;
 102                         goto error_release_channels;
 103                 }
 104
 105                 sysfs_attr_init(&a->dev_attr.attr);
 106                 ret = iio_get_channel_type(&st->channels[i], &type);
 107                 if (ret < 0)
 108                         goto error_release_channels;
 109
 110                 switch (type) {
 111                 case IIO_VOLTAGE:
 112                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 113                                                           "in%d_input",
 114                                                           in_i++);
 115                         break;
 116                 case IIO_TEMP:
 117                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 118                                                           "temp%d_input",
 119                                                           temp_i++);
 120                         break;
 121                 case IIO_CURRENT:
 122                         a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
 123                                                           "curr%d_input",
 124                                                           curr_i++);
 125                         break;
 126                 default:
 127                         ret = -EINVAL;
 128                         goto error_release_channels;
 129                 }
 130                 if (a->dev_attr.attr.name == NULL) {
 131                         ret = -ENOMEM;
 132                         goto error_release_channels;
 133                 }
 134                 a->dev_attr.show = iio_hwmon_read_val;
 135                 a->dev_attr.attr.mode = S_IRUGO;
 136                 a->index = i;
 137                 st->attrs[i] = &a->dev_attr.attr;
 138         }
 139
 140         st->attr_group.attrs = st->attrs;
 141         st->groups[0] = &st->attr_group;
 142         st->hwmon_dev = hwmon_device_register_with_groups(dev, name, st,
 143                                                           st->groups);
 144         if (IS_ERR(st->hwmon_dev)) {
 145                 ret = PTR_ERR(st->hwmon_dev);
 146                 goto error_release_channels;
 147         }
 148         platform_set_drvdata(pdev, st);
 149         return 0;
 150
 151 error_release_channels:
 152         iio_channel_release_all(channels);
 153         return ret;
 154 }
 155
 156 static int iio_hwmon_remove(struct platform_device *pdev)
 157 {
 158         struct iio_hwmon_state *st = platform_get_drvdata(pdev);
 159
 160         hwmon_device_unregister(st->hwmon_dev);
 161         iio_channel_release_all(st->channels);
 162
 163         return 0;
 164 }
 165
 166 static const struct of_device_id iio_hwmon_of_match[] = {
 167         { .compatible = "iio-hwmon", },
 168         { }
 169 };
 170 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
 171
 172 static struct platform_driver __refdata iio_hwmon_driver = {
 173         .driver = {
 174                 .name = "iio_hwmon",
 175                 .owner = THIS_MODULE,
 176                 .of_match_table = iio_hwmon_of_match,
 177         },
 178         .probe = iio_hwmon_probe,
 179         .remove = iio_hwmon_remove,
 180 };
 181
 182 module_platform_driver(iio_hwmon_driver);
 183
 184 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 185 MODULE_DESCRIPTION("IIO to hwmon driver");
 186 MODULE_LICENSE("GPL v2");