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
  48         ret = iio_read_channel_processed(&state->channels[sattr->index],
  49                                         &result);
  50         if (ret < 0)
  51                 return ret;
  52
  53         return sprintf(buf, "%d\n", result);
  54 }
  55
  56 static int iio_hwmon_probe(struct platform_device *pdev)
  57 {
  58         struct device *dev = &pdev->dev;
  59         struct iio_hwmon_state *st;
  60         struct sensor_device_attribute *a;
  61         int ret, i;
  62         int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1;
  63         enum iio_chan_type type;
  64         struct iio_channel *channels;
  65         struct device *hwmon_dev;
  66         char *sname;
  67
  68         channels = devm_iio_channel_get_all(dev);
  69         if (IS_ERR(channels)) {
  70                 if (PTR_ERR(channels) == -ENODEV)
  71                         return -EPROBE_DEFER;
  72                 return PTR_ERR(channels);
  73         }
  74
  75         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
  76         if (st == NULL)
  77                 return -ENOMEM;
  78
  79         st->channels = channels;
  80
  81         /* count how many attributes we have */
  82         while (st->channels[st->num_channels].indio_dev)
  83                 st->num_channels++;
  84
  85         st->attrs = devm_kcalloc(dev,
  86                                  st->num_channels + 1, sizeof(*st->attrs),
  87                                  GFP_KERNEL);
  88         if (st->attrs == NULL)
  89                 return -ENOMEM;
  90
  91         for (i = 0; i < st->num_channels; i++) {
  92                 const char *prefix;
  93                 int n;
  94
  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                         n = in_i++;
 107                         prefix = "in";
 108                         break;
 109                 case IIO_TEMP:
 110                         n = temp_i++;
 111                         prefix = "temp";
 112                         break;
 113                 case IIO_CURRENT:
 114                         n = curr_i++;
 115                         prefix = "curr";
 116                         break;
 117                 case IIO_HUMIDITYRELATIVE:
 118                         n = humidity_i++;
 119                         prefix = "humidity";
 120                         break;
 121                 default:
 122                         return -EINVAL;
 123                 }
 124
 125                 a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 126                                                        "%s%d_input",
 127                                                        prefix, n);
 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 = 0444;
 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 <jic23@kernel.org>");
 171 MODULE_DESCRIPTION("IIO to hwmon driver");
 172 MODULE_LICENSE("GPL v2");