drivers/hwmon/iio_hwmon.c

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