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/module.h>
  10 #include <linux/err.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/hwmon.h>
  13 #include <linux/of.h>
  14 #include <linux/hwmon-sysfs.h>
  15 #include <linux/iio/consumer.h>
  16 #include <linux/iio/types.h>
  17
  18 /**
  19  * struct iio_hwmon_state - device instance state
  20  * @channels:           filled with array of channels from iio
  21  * @num_channels:       number of channels in channels (saves counting twice)
  22  * @attr_group:         the group of attributes
  23  * @groups:             null terminated array of attribute groups
  24  * @attrs:              null terminated array of attribute pointers.
  25  */
  26 struct iio_hwmon_state {
  27         struct iio_channel *channels;
  28         int num_channels;
  29         struct attribute_group attr_group;
  30         const struct attribute_group *groups[2];
  31         struct attribute **attrs;
  32 };
  33
  34 /*
  35  * Assumes that IIO and hwmon operate in the same base units.
  36  * This is supposed to be true, but needs verification for
  37  * new channel types.
  38  */
  39 static ssize_t iio_hwmon_read_val(struct device *dev,
  40                                   struct device_attribute *attr,
  41                                   char *buf)
  42 {
  43         int result;
  44         int ret;
  45         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  46         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  47         struct iio_channel *chan = &state->channels[sattr->index];
  48         enum iio_chan_type type;
  49
  50         ret = iio_read_channel_processed(chan, &result);
  51         if (ret < 0)
  52                 return ret;
  53
  54         ret = iio_get_channel_type(chan, &type);
  55         if (ret < 0)
  56                 return ret;
  57
  58         if (type == IIO_POWER)
  59                 result *= 1000; /* mili-Watts to micro-Watts conversion */
  60
  61         return sprintf(buf, "%d\n", result);
  62 }
  63
  64 static int iio_hwmon_probe(struct platform_device *pdev)
  65 {
  66         struct device *dev = &pdev->dev;
  67         struct iio_hwmon_state *st;
  68         struct sensor_device_attribute *a;
  69         int ret, i;
  70         int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
  71         enum iio_chan_type type;
  72         struct iio_channel *channels;
  73         struct device *hwmon_dev;
  74         char *sname;
  75
  76         channels = devm_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                 return -ENOMEM;
  86
  87         st->channels = channels;
  88
  89         /* count how many attributes we have */
  90         while (st->channels[st->num_channels].indio_dev)
  91                 st->num_channels++;
  92
  93         st->attrs = devm_kcalloc(dev,
  94                                  st->num_channels + 1, sizeof(*st->attrs),
  95                                  GFP_KERNEL);
  96         if (st->attrs == NULL)
  97                 return -ENOMEM;
  98
  99         for (i = 0; i < st->num_channels; i++) {
 100                 const char *prefix;
 101                 int n;
 102
 103                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 104                 if (a == NULL)
 105                         return -ENOMEM;
 106
 107                 sysfs_attr_init(&a->dev_attr.attr);
 108                 ret = iio_get_channel_type(&st->channels[i], &type);
 109                 if (ret < 0)
 110                         return ret;
 111
 112                 switch (type) {
 113                 case IIO_VOLTAGE:
 114                         n = in_i++;
 115                         prefix = "in";
 116                         break;
 117                 case IIO_TEMP:
 118                         n = temp_i++;
 119                         prefix = "temp";
 120                         break;
 121                 case IIO_CURRENT:
 122                         n = curr_i++;
 123                         prefix = "curr";
 124                         break;
 125                 case IIO_POWER:
 126                         n = power_i++;
 127                         prefix = "power";
 128                         break;
 129                 case IIO_HUMIDITYRELATIVE:
 130                         n = humidity_i++;
 131                         prefix = "humidity";
 132                         break;
 133                 default:
 134                         return -EINVAL;
 135                 }
 136
 137                 a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 138                                                        "%s%d_input",
 139                                                        prefix, n);
 140                 if (a->dev_attr.attr.name == NULL)
 141                         return -ENOMEM;
 142
 143                 a->dev_attr.show = iio_hwmon_read_val;
 144                 a->dev_attr.attr.mode = 0444;
 145                 a->index = i;
 146                 st->attrs[i] = &a->dev_attr.attr;
 147         }
 148
 149         st->attr_group.attrs = st->attrs;
 150         st->groups[0] = &st->attr_group;
 151
 152         if (dev->of_node) {
 153                 sname = devm_kasprintf(dev, GFP_KERNEL, "%pOFn", dev->of_node);
 154                 if (!sname)
 155                         return -ENOMEM;
 156                 strreplace(sname, '-', '_');
 157         } else {
 158                 sname = "iio_hwmon";
 159         }
 160
 161         hwmon_dev = devm_hwmon_device_register_with_groups(dev, sname, st,
 162                                                            st->groups);
 163         return PTR_ERR_OR_ZERO(hwmon_dev);
 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 iio_hwmon_driver = {
 173         .driver = {
 174                 .name = "iio_hwmon",
 175                 .of_match_table = iio_hwmon_of_match,
 176         },
 177         .probe = iio_hwmon_probe,
 178 };
 179
 180 module_platform_driver(iio_hwmon_driver);
 181
 182 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 183 MODULE_DESCRIPTION("IIO to hwmon driver");
 184 MODULE_LICENSE("GPL v2");