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 static ssize_t iio_hwmon_read_label(struct device *dev,
  37                                   struct device_attribute *attr,
  38                                   char *buf)
  39 {
  40         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  41         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  42         struct iio_channel *chan = &state->channels[sattr->index];
  43
  44         return iio_read_channel_label(chan, buf);
  45 }
  46
  47 /*
  48  * Assumes that IIO and hwmon operate in the same base units.
  49  * This is supposed to be true, but needs verification for
  50  * new channel types.
  51  */
  52 static ssize_t iio_hwmon_read_val(struct device *dev,
  53                                   struct device_attribute *attr,
  54                                   char *buf)
  55 {
  56         int result;
  57         int ret;
  58         struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
  59         struct iio_hwmon_state *state = dev_get_drvdata(dev);
  60         struct iio_channel *chan = &state->channels[sattr->index];
  61         enum iio_chan_type type;
  62
  63         ret = iio_get_channel_type(chan, &type);
  64         if (ret < 0)
  65                 return ret;
  66
  67         if (type == IIO_POWER)
  68                 /* mili-Watts to micro-Watts conversion */
  69                 ret = iio_read_channel_processed_scale(chan, &result, 1000);
  70         else
  71                 ret = iio_read_channel_processed(chan, &result);
  72         if (ret < 0)
  73                 return ret;
  74
  75         return sprintf(buf, "%d\n", result);
  76 }
  77
  78 static int iio_hwmon_probe(struct platform_device *pdev)
  79 {
  80         struct device *dev = &pdev->dev;
  81         struct iio_hwmon_state *st;
  82         struct sensor_device_attribute *a;
  83         int ret, i, attr = 0;
  84         int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
  85         enum iio_chan_type type;
  86         struct iio_channel *channels;
  87         struct device *hwmon_dev;
  88         char *sname;
  89         void *buf;
  90
  91         channels = devm_iio_channel_get_all(dev);
  92         if (IS_ERR(channels)) {
  93                 ret = PTR_ERR(channels);
  94                 if (ret == -ENODEV)
  95                         ret = -EPROBE_DEFER;
  96                 return dev_err_probe(dev, ret,
  97                                      "Failed to get channels\n");
  98         }
  99
 100         st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
 101         buf = (void *)devm_get_free_pages(dev, GFP_KERNEL, 0);
 102         if (!st || !buf)
 103                 return -ENOMEM;
 104
 105         st->channels = channels;
 106
 107         /* count how many channels we have */
 108         while (st->channels[st->num_channels].indio_dev)
 109                 st->num_channels++;
 110
 111         st->attrs = devm_kcalloc(dev,
 112                                  2 * st->num_channels + 1, sizeof(*st->attrs),
 113                                  GFP_KERNEL);
 114         if (st->attrs == NULL)
 115                 return -ENOMEM;
 116
 117         for (i = 0; i < st->num_channels; i++) {
 118                 const char *prefix;
 119                 int n;
 120
 121                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 122                 if (a == NULL)
 123                         return -ENOMEM;
 124
 125                 sysfs_attr_init(&a->dev_attr.attr);
 126                 ret = iio_get_channel_type(&st->channels[i], &type);
 127                 if (ret < 0)
 128                         return ret;
 129
 130                 switch (type) {
 131                 case IIO_VOLTAGE:
 132                         n = in_i++;
 133                         prefix = "in";
 134                         break;
 135                 case IIO_TEMP:
 136                         n = temp_i++;
 137                         prefix = "temp";
 138                         break;
 139                 case IIO_CURRENT:
 140                         n = curr_i++;
 141                         prefix = "curr";
 142                         break;
 143                 case IIO_POWER:
 144                         n = power_i++;
 145                         prefix = "power";
 146                         break;
 147                 case IIO_HUMIDITYRELATIVE:
 148                         n = humidity_i++;
 149                         prefix = "humidity";
 150                         break;
 151                 default:
 152                         return -EINVAL;
 153                 }
 154
 155                 a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 156                                                        "%s%d_input",
 157                                                        prefix, n);
 158                 if (a->dev_attr.attr.name == NULL)
 159                         return -ENOMEM;
 160
 161                 a->dev_attr.show = iio_hwmon_read_val;
 162                 a->dev_attr.attr.mode = 0444;
 163                 a->index = i;
 164                 st->attrs[attr++] = &a->dev_attr.attr;
 165
 166                 /* Let's see if we have a label... */
 167                 if (iio_read_channel_label(&st->channels[i], buf) < 0)
 168                         continue;
 169
 170                 a = devm_kzalloc(dev, sizeof(*a), GFP_KERNEL);
 171                 if (a == NULL)
 172                         return -ENOMEM;
 173
 174                 sysfs_attr_init(&a->dev_attr.attr);
 175                 a->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
 176                                                        "%s%d_label",
 177                                                        prefix, n);
 178                 if (!a->dev_attr.attr.name)
 179                         return -ENOMEM;
 180
 181                 a->dev_attr.show = iio_hwmon_read_label;
 182                 a->dev_attr.attr.mode = 0444;
 183                 a->index = i;
 184                 st->attrs[attr++] = &a->dev_attr.attr;
 185         }
 186
 187         devm_free_pages(dev, (unsigned long)buf);
 188
 189         st->attr_group.attrs = st->attrs;
 190         st->groups[0] = &st->attr_group;
 191
 192         if (dev_fwnode(dev)) {
 193                 sname = devm_kasprintf(dev, GFP_KERNEL, "%pfwP", dev_fwnode(dev));
 194                 if (!sname)
 195                         return -ENOMEM;
 196                 strreplace(sname, '-', '_');
 197         } else {
 198                 sname = "iio_hwmon";
 199         }
 200
 201         hwmon_dev = devm_hwmon_device_register_with_groups(dev, sname, st,
 202                                                            st->groups);
 203         return PTR_ERR_OR_ZERO(hwmon_dev);
 204 }
 205
 206 static const struct of_device_id iio_hwmon_of_match[] = {
 207         { .compatible = "iio-hwmon", },
 208         { }
 209 };
 210 MODULE_DEVICE_TABLE(of, iio_hwmon_of_match);
 211
 212 static struct platform_driver iio_hwmon_driver = {
 213         .driver = {
 214                 .name = "iio_hwmon",
 215                 .of_match_table = iio_hwmon_of_match,
 216         },
 217         .probe = iio_hwmon_probe,
 218 };
 219
 220 module_platform_driver(iio_hwmon_driver);
 221
 222 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 223 MODULE_DESCRIPTION("IIO to hwmon driver");
 224 MODULE_LICENSE("GPL v2");