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